119
AITES ITA Towards an improved use of underground Space In Consultative Status, Category II with the United Nations Economic and Social Council http://www.ita-aites.org ASSOCIATION INTERNATIONALE DES TRAVAUX EN SOUTERRAIN INTERNATIONAL TUNNELLING ASSOCIATION Recommendations and Guidelines for Tunnel Boring Machines (TBMs) MECHANIZED TUNNELLING Title Topic published Abstract: - Résumé: - Remarks: This report contains four individual reports prepared by ITA Working Group No. 14 ("Mechanized Tunnelling"). The purpose of the reports is to provide comprehensive guidelines and recommendations for evaluating and selecting Tunnel Boring Machines (TBMs) for both soft ground and hard rock. The reports are contributed by representatives from seven countries as follows: I. "Guide lines for Selecting TBMs for Soft Ground", Japan and Norway II. "Recommendations of Selecting and Evaluating Tunnel Boring Machines", Germany, Switzerland and Austria III. "Guidelines for the Selection of TBMs", Italy IV. "New Recommendations on Choosing Mechanized Tunnelling Techniques", France Each report offers up to date technologies of mechanized tunneling for both hard and soft ground and includes, among others, classifications of TBMs, their application criteria, construction methods, ground supporting system and other equipment necessary for driving tunnels by TBMs. Since a cylindrical steel shield was first used for the construction of the Themes River Tunnel Crossing in England in 1823, tunnel works have been steadily mechanized. Especially, as urban tunneling was developed in the latter half of the 20th century, technological progress seen in this area was remarkable. Meanwhile, the circumstances surrounding tunnel construction have become increasingly complex and difficult. Tunneling technologies in recent years are developed by sophisticated and multi-disciplinary engineering principles to cope with the diverse physical, environmental and social circumstances. This report is intended to provide fundamental and useful knowledge of mechanical tunneling that can be used by designers, manufacturers and the end users of tunnel boring machines. It is hoped that this report provides common ground for understanding tunneling technologies among international tunneling communities and eventually helps establish a standard set of criteria for designing and utilizing tunnel boring machines. in "Recommendations and Guidelines for Tunnel Boring Machines (TBMs)", Working Group: WG 14 - "Mechanized Tunnelling" Author ITA WG Mechanized Tunnelling Open Session, Seminar, Workshop: - Others: Recommendations by ITA - AITES, www.ita-aites.org pp. 1 - 118, Year 2000 Secretariat : ITA-AITES c/o EPFL - Bât. GC – CH-1015 Lausanne - Switzerland Fax : +41 21 693 41 53 - Tel. : +41 21 693 23 10 - e-mail : [email protected] - www.ita-aites.org

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Page 1: Recommendations ITA TBM

AITES

ITA

Towards animproved use

of undergroundSpace

In Consultative Status, Category II with theUnited Nations Economic and Social Council

http://www.ita-aites.org

ASSOCIATIONINTERNATIONALE DES TRAVAUX

EN SOUTERRAININTERNATIONALTUNNELLINGASSOCIATION

Recommendations and Guidelines for Tunnel Boring Machines (TBMs)

MECHANIZED TUNNELLING

Title

Topic

published

Abstract: -

Résumé: -

Remarks: This report contains four individual reports prepared by ITA Working Group No. 14 ("Mechanized

Tunnelling"). The purpose of the reports is to provide comprehensive guidelines and recommendations for

evaluating and selecting Tunnel Boring Machines (TBMs) for both soft ground and hard rock. The reports are

contributed by representatives from seven countries as follows:

I. "Guide lines for Selecting TBMs for Soft Ground", Japan and Norway

II. "Recommendations of Selecting and Evaluating Tunnel Boring Machines", Germany, Switzerland and

Austria

III. "Guidelines for the Selection of TBMs", Italy

IV. "New Recommendations on Choosing Mechanized Tunnelling Techniques", France

Each report offers up to date technologies of mechanized tunneling for both hard and soft ground and includes,

among others, classifications of TBMs, their application criteria, construction methods, ground supporting

system and other equipment necessary for driving tunnels by TBMs.

Since a cylindrical steel shield was first used for the construction of the Themes River Tunnel Crossing in

England in 1823, tunnel works have been steadily mechanized. Especially, as urban tunneling was developed in

the latter half of the 20th century, technological progress seen in this area was remarkable. Meanwhile, the

circumstances surrounding tunnel construction have become increasingly complex and difficult. Tunneling

technologies in recent years are developed by sophisticated and multi-disciplinary engineering principles to

cope with the diverse physical, environmental and social circumstances. This report is intended to provide

fundamental and useful knowledge of mechanical tunneling that can be used by designers, manufacturers and

the end users of tunnel boring machines.

It is hoped that this report provides common ground for understanding tunneling technologies among

international tunneling communities and eventually helps establish a standard set of criteria for designing and

utilizing tunnel boring machines.

in "Recommendations and Guidelines for Tunnel Boring Machines (TBMs)",

Working Group: WG 14 - "Mechanized Tunnelling"

AuthorITA WG Mechanized Tunnelling

Open Session, Seminar, Workshop: -

Others: Recommendations

by ITA - AITES, www.ita-aites.org

pp. 1 - 118, Year 2000

Secretariat : ITA-AITES c/o EPFL - Bât. GC – CH-1015 Lausanne - SwitzerlandFax : +41 21 693 41 53 - Tel. : +41 21 693 23 10 - e-mail : [email protected] - www.ita-aites.org

Page 2: Recommendations ITA TBM

RECOMMENDATIONS AND GUIDELINESFOR TUNNEL BORING MACHINES (TBMs)

TRIBUNE HORS SÉRIEMAI 2001 - ISSN 1267-8422

WORKING GROUP N°14 - MECHANIZED TUNNELLING - INTERNATIONAL TUNNELLING ASSOCIATION

ASSOCIATIONINTERNATIONALE DES TRAVAUX

EN SOUTERRAIN

AITESITAINTERNATIONALTUNNELLINGASSOCIATION

Page 3: Recommendations ITA TBM

International Tunnelling Association25, Avenue François Mitterrand – Case nº1

69674 BRON CedexFranceTEL: 33(0) 4 78 26 04 55FAX: 33(0) 4 72 37 24 06e-mail: [email protected]://www.ita-aites.org

© International Tunnelling Association. All rights reserved. No part of this publication may bedistributed and/or reproduced, stored in a retrieval system or transmitted in any form or by anymeans, electronic, mechanical, photocopying, recording or otherwise , without the prior writtenpermission of publisher, International Tunneling Association

Page 4: Recommendations ITA TBM

Preface

This report contains four individual reports prepared by ITA Working Group No. 14 (“MechanizedTunneling”). The purpose of the reports is to provide comprehensive guidelines andrecommendations for evaluating and selecting Tunnel Boring Machines (TBMs) for both soft groundand hard rock. The reports are contributed by representatives from seven countries as follows:

I. “Guide lines for Selecting TBMs for Soft Ground”, Japan and NorwayII. “Recommendations of Selecting and Evaluating Tunnel Boring Machines”, Germany,

Switzerland and AustriaIII. “Guidelines for the Selection of TBMs”, ItalyIV. “New Recommendations on Choosing Mechanized Tunnelling Techniques”, France

Each report offers up to date technologies of mechanized tunneling for both hard and soft groundand includes, among others, classifications of TBMs, their application criteria, construction methods,ground supporting system and other equipment necessary for driving tunnels by TBMs.

Since a cylindrical steel shield was first used for the construction of the Themes River TunnelCrossing in England in 1823, tunnel works have been steadily mechanized. Especially, as urbantunneling was developed in the latter half of the 20th century, technological progress seen in this areawas remarkable. Meanwhile, the circumstances surrounding tunnel construction have becomeincreasingly complex and difficult. Tunneling technologies in recent years are developed bysophisticated and multi-disciplinary engineering principles to cope with the diverse physical,environmental and social circumstances. This report is intended to provide fundamental and usefulknowledge of mechanical tunneling that can be used by designers, manufacturers and the end usersof tunnel boring machines.

It is hoped that this report provides common ground for understanding tunneling technologies amonginternational tunneling communities and eventually helps establish a standard set of criteria fordesigning and utilizing tunnel boring machines.

Shoji KuwaharaTutor, Working Group No. 14International Tunnell ing Association

Page 5: Recommendations ITA TBM

GENERAL CONTENTS

I. GUIDELINES FOR SELECTING TBMS FOR SOFT GROUNDby Japan and Norway

1 Classification of tunnel excavation machine2 Investigation of existing conditions and applicability of TBM3 Tunnel boring machine (TBM)4 Tunnels constructed by TBM in JapanAPPENDIX: TBM Performance in hard rock

II. RECOMMENDATIONS OF SELECTING AND EVALUATINGTUNNEL BORING MACHINES

by Germany, Switzerland and Austria

1. Purpose of the recommendations2. Geotechnics3. Construction methods for mined tunnels4. Tunneling machines TM5. Relationship between geotechnics and tunneling machines

III. GUIDELINES FOR THE SELECTION OF TBMSby Italy

1. Classification and outlines of tunnel excavation machines2. Conditions for tunnel construction and selection of TBM tunneling method3. References

IV. NEW RECOMMENDATIONS ON CHOOSING MECHANIZEDTUNNELLING TECHNIQUES

by France

1. Purpose of these recommendations2. Mechanized tunnelling techniques3. Classification of mechanized tunneling Techniques4. Definition of the different mechanized tunnelling techniques classified in chapter 35. Evaluation of parameters for choice of mechanized tunneling techniques6. Specific features of the different tunneling techniques7. Application of mechanized tunneling techniques8. Techniques accompanying mechanized tunneling9. Health & Safety

Page 6: Recommendations ITA TBM

Japan and Norway

Guidelines for Selecting TBMsfor Soft Ground

ITA Working Group No. 14Mechanized Tunneling

Page 7: Recommendations ITA TBM

I-ii

PREFACE

Tunnels are playing an important role in the development of urban infrastructures. Severalconstruction methods for tunneling have been developed to cope with various geological conditions.Those methods can be categorized in two types; drill and blast method and by the use of TunnelBoring Machine (TBM). This report focuses on tunneling by TBM and is prepared to offerguidelines and recommendations for selecting types of TBMs for urban tunnel construction. Itsmain purpose is to help project owners, contractors and manufacturers evaluate the applicability andcapability of TBMs and other factors that should be taken into consideration for selecting of TBMs.

ITA has been collecting data and information from its member countries, in hope of providing acomprehensive international “manual” for TBM tunneling methods. As the contents of this reportrepresent Japanese and Norwegian versions of the subject, they may be revised or supplemented asnecessary to meet particular conditions of the respective countries.

This report consists of two parts; one is for the TBMs in soft ground prepared by Japanese WorkingGroup and the other is for the TBMs in hard rock prepared by Norwegian Working Group. TheNorwegian version is an excerpt from the “Project Report 1-94, Hard Rock Tunnel Boring”published by University of Trondheim, Norway, and is included in Appendix. Small diametertunneling is not included in this report (e.g. micro-tunneling with pipe jacking etc.).

Technologies surrounding TBMs have been receiving great deal of attention. They have beenprimarily aimed at mechanization and automation of tunnel boring under various geologicalconditions, with the combined technologies of soil, mechanic and electronic engineering. Thetechnological progress will continue to come from innovative commitments of tunnel builders,teaming with tunnel designers and manufacturers.

It is hoped that this report will assist the members of ITA publish the comprehensive internationalmanual for TBMs and will further contribute to the development of tunneling technologies.

Page 8: Recommendations ITA TBM

I-iii

CONTENTS

1 CLASSIFICATION OF TUNNEL EXCAVATION MACHINE...............................................................................11.1 Mechanical Excavation Type (Fig. 1.3) ...................................................................................................................31.2 Earth Pressure Balance (E.P.B.) Type (Fig. 1.4).....................................................................................................31.3 Slurry Type (Fig. 1.5) .................................................................................................................................................4

2 INVESTIGATIONS OF EXISTING CONDITIONS AND APPLICABILITY OF TBM....................................52.1 Site Investigations........................................................................................................................................................5

2.1.1. Existing site conditions ....................................................................................................................................52.1.2. Existing structures and utilities .......................................................................................................................52.1.3. Topography and geology..................................................................................................................................52.1.4. Environmental impact.......................................................................................................................................5

2.2 Applicability of TBMs ...............................................................................................................................................53 TUNNEL BORING MACHINE (TBM) ......................................................................................................................8

3.1 Machine Specifications ..............................................................................................................................................83.1.1. Essential parts of TBM.....................................................................................................................................83.1.2. Structure of TBM..............................................................................................................................................83.1.3. Types of TBMs for soft ground.......................................................................................................................93.1.4. Selection of TBM..............................................................................................................................................9

3.2 Orientation and operation of machine................................................................................................................... 123.2.1. Excavation Control System .......................................................................................................................... 123.2.2. Direction Control and Measurement System ............................................................................................. 12

3.3 Cutter Consumption................................................................................................................................................. 123.3.1. Bit types and Arrangement ........................................................................................................................... 123.3.2. Wear of Bit...................................................................................................................................................... 123.3.3. Long Distance Excavation ............................................................................................................................ 12

3.4 Ground Support and Lining.................................................................................................................................... 133.4.1. Design of Lining............................................................................................................................................. 133.4.2. Types of Segment........................................................................................................................................... 133.4.3. Fabrication of Segment.................................................................................................................................. 143.4.4. Erection of Segments..................................................................................................................................... 15

3.5 Auxiliary Facilities................................................................................................................................................... 163.5.1. Earth pressure balance type machine .......................................................................................................... 163.5.2. Slurry type tunneling machine ..................................................................................................................... 17

4 TUNNELS CONSTRUCTED BY TBM IN JAPAN ............................................................................................... 174.1 Soft ground tunneling in Japan .............................................................................................................................. 174.2 Types of TBMs and ground conditions................................................................................................................. 18

4.2.1. Soil Conditions and Types of TBMs ........................................................................................................... 184.2.2. Groundwater pressure and Type of TBMs.................................................................................................. 19 Max. Size of Gravel and TBM Type ......................................................................................................................... 20

4.3 Size of TBM.............................................................................................................................................................. 21Weight............................................................................................................................................................................. 21Length/Diameter (L/D) ................................................................................................................................................ 21

APPENDIX: TBM PERFORMANCE IN HARD ROCK .............................................................................................. 22A-1 General......................................................................................................................................................................... 22A-2 Advance ....................................................................................................................................................................... 22

A-2.1 Rock Mass Properties........................................................................................................................................ 22A-2.2 Machine Parameters........................................................................................................................................... 24A-2.3 Other Definitions................................................................................................................................................ 26A-2.4 Gross advance rate............................................................................................................................................. 28A-2.5 Additional Time Consumption ......................................................................................................................... 29

A-3 Cutter Consumption ................................................................................................................................................... 30A-4 Troubles and Countermeasures................................................................................................................................. 32

A-4.1 Causes for Trouble............................................................................................................................................. 32A-4.2 Countermeasures ................................................................................................................................................ 33

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I-iv

FIGURES

FIG. 1.1 CLASSIFICATION OF TUNNEL EXCAVATION MACHINES ........................................................................1FIG. 1.2 TUNNEL EXCAVATION MACHINES .........................................................................................................2FIG. 1.3 MECHANICAL EXCAVATION TYPE TUNNELING MACHINE....................................................................3FIG. 1.4 EARTH PRESSURE BALANCE TYPE TUNNELING MACHINE...................................................................4FIG. 1.5 SLURRY TYPE TUNNELING MACHINE ...................................................................................................4FIG. 3.1 COMPONENTS OF TUNNELING MACHINE ..............................................................................................8FIG. 3.2 TYPE OF TBM FOR SOFT GROUND.......................................................................................................9FIG. 3.3 FLOW CHART FOR SELECTING TBM FOR SOFT GROUND..................................................................10FIG. 4.1 TUNNELS DRIVEN BY TBMS IN JAPAN ...............................................................................................17FIG. 4.2 SOIL CONDITIONS AND TYPE OF TBMS .............................................................................................18FIG. 4.3 GROUNDWATER PRESSURE AND TYPE OF TBMS ...............................................................................19FIG. 4.4 GRAVEL SIZE AND TYPE OF TBMS ....................................................................................................20FIG. 4.5 DIAMETER AND WEIGHT OF TBM (EPB, SLURRY)............................................................................21FIG. 4.6 DIAMETER AND LENGTH/DIAMETER (L/D) OF TBM ..........................................................................21FIG. A.1 RECORDED DRILLING RATE INDEX FOR VARIOUS ROCK TYPES ........................................................22FIG.A.2 RECORDED CUTTER LIFE INDEX FOR VARIOUS ROCK TYPES .............................................................23FIG. A.3 FRACTURE CLASSES WITH CORRESPONDING DISTANCE BETWEEN PLANES OF WEAKNESS ..............23FIG. A.4 RECORDED DEGREE OF FRACTURING FOR VARIOUS ROCK TYPES .....................................................24FIG. A.5 FRACTURING FACTOR, CORRECTION FACTOR FOR DRI≠49..............................................................24FIG. A.6 RECOMMENDED MAX. GROSS AVERAGE PER DISC.............................................................................25FIG. A.7 CUTTERHEAD R.P.M. AS FUNCTION OF TBM-DIAMETER...................................................................25FIG. A.8 BASIC PENETRATION FOR CUTTER DIAMETER = 48.3 MM AND CUTTER SPACING = 70 MM..............26FIG. A.9 CORRECTION FACTOR FOR CUTTER DIAMETER≠483 MM ..................................................................27FIG. A.10 CORRECTION FACTOR FOR AVERAGE CUTTER SPACING≠70 MM......................................................27FIG. A.11 CUTTING CONSTANT CC AS A FUNCTION OF CUTTER DIAMETER ....................................................28FIG. A.12 MAINTENANCE AS FUNCTION OF NET PENETRATION RATE..............................................................29FIG. A.13 BASIC CUTTER RING LIFE AS FUNCTION OF CLI AND CUTTER DIAMETER.......................................31FIG. A.14 CORRECTION FACTOR FOR CUTTING RING LIFE.............................................................................31FIG. A.15 CORRECTION FACTOR FOR CUTTING RING VS. QUARTZ CONTENT.................................................32

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I-v

TABLES

TABLE 2.1 COMPARISON OF EXCAVATION METHODS.............................................................................................................6TABLE 2.2 APPLICABILITY OF TBMS TO SOFT GROUND CONDITIONS...............................................................................7TABLE 3.1 RELATIONSHIP BETWEEN CLOSED TYPE TUNNELING MACHINE AND SOIL CONDITIONS.......................... 11TABLE 3.2 LOADS ON SEGMENTS ......................................................................................................................................... 13TABLE 3.3 ALLOWABLE STRESSES OF CONCRETE FOR PRE-FABRICATED CONCRETE SEGMENTS ................................. 14TABLE 3.4 TYPICAL DIMENSIONS OF SEGMENTS (MM)..................................................................................................... 15TABLE 3.5 AUXILIARY FACILITIES........................................................................................................................................ 16TABLE 4.1 TBMS IN SOFT GROUND PERFORMED IN JAPAN ............................................................................................... 17

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I-1

1 CLASSIFICATION OF TUNNELEXCAVATION MACHINE

Tunnels are constructed under many types ofgeological conditions varying from hard rockto very soft sedimentary layers. Procedurescommonly taken for tunneling are excavation,ground support, mucking and lining. Varietyof construction methods have been developedfor tunneling such as cut and cover, drill andblast, submerged tube, push or pulling box, andby the use of tunnel boring machine (TBM).

TBM was first put into practical use for miningof hard rock, where the face of the tunnel isbasically self-standing. For tunneling throughearth, open type machine was used, in which ametal shield was primarily used for protectivedevice for excavation works.

For tunneling through sedimentary soil,tunnel face is stabilized by breasting,pneumatic pressure or other supporting means.Closed type- tunneling machine wasdeveloped, which utilizes compressed air tostabilize tunnel face. The closed type-machinestarted to dominate for soft ground tunneling,especially in the countries where many tunnelsare driven through sedimentary soil layers.

Tunnel excavation machines can be classifiedby the methods for excavation (full face orpartial face), the types of cutter head (rotationor non-rotation), and by the methods ofsecuring reaction force (from gripper orsegment). Several types of tunnel excavationmachines are illustrated in Fig. 1.1 and Fig.1.2,

Fig. 1.1 Classification of Tunnel Excavation Machines

Page 12: Recommendations ITA TBM
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I-3

1.1 Mechanical Excavation Type (Fig. 1.3)

The mechanical excavation type-tunnelingmachine is equipped with a rotary cutter headfor continuous excavation of tunnel face.There are two types of cutter heads; one is thedisk type and the other is the spoke type (rodstyle radiating from the center). The disk typeis suitable for large cross section tunnelswhere tunnel face is stabilized by the diskcutter head. This type of machine is capableof excavating soils containing gravel andboulders with the openings in the disk, whichare adjustable according to the size of graveland boulders. The spoke type is frequentlyused for small cross section tunnels where thetunneling face is relatively stable. Gravel andboulders are removed by the rotating spokecutter.The mechanical excavation type-tunnelingmachine is suitable for the diluvial depositthat has a self-standing face. Application ofthis type of machine to the alluvial deposits,which usually do not form a self-standingface, requires one or more supplementarymethods such as pneumatic pressure,additional de-watering, and chemicalgrouting.

Hopper

Cutter driving mo

Belt conveyo

Cutter head

Fig. 1.3 Mechanical Excavation TypeTunneling Machine

1.2 Earth Pressure Balance (E.P.B.) Type(Fig. 1.4)

Earth pressure balance type tunnelingmachine converts excavated soil into high-

density slurry mix. The face of the tunnel issupported by the pressurized slurry mixinjected into a space between its cutter headand a watertight steel bulkhead. It consists ofthe following four components:

i) A cutter head for excavating thegroundii) A slurry mixer for mixing theexcavated muck with high-density slurryiii) Soil-discharging devise for removalof the muckiv) Pressure controlling devise forkeeping the pressure of slurry-soil mixsteady

The earth pressure balance type is classifiedinto two types by the additives injected toconvert the excavated muck into high-densityslurry. One is earth pressure type and theother is high-density slurry type.

(1) Earth pressure typeEarth pressure type machine cut the groundwith a rotary cutter head. Clay-water slurryis injected into the cutter chamber and ismixed with excavated muck. The slurry mixis pressurized to stabilize the tunnel face andcreate the driving force of the machine. Theexcavated muck is later separated from theslurry and discharged by a screw conveyor.This type is suitable for clayey soil layers.

(2) High-density slurry typeHigh-density slurry type machine cut theground with a rotary cutter head. Theexcavated muck is mixed with clay-waterslurry. by the rotating cutter. Highly plasticand dense additive is added to the slurry mixin the cutter chamber. The additives areused to increase the fluidity and to reducethe permeability of the soil. The high-density slurry mix stabilizes the tunnel face.The excavated muck is discharged by ascrew conveyor. This type is suitable forsand or gravel layers.

Page 14: Recommendations ITA TBM

I-4

Cutter headCutter driving motor

Mixing wingCutter chamber

Screw conveyor

Additives

Fig. 1.4 Earth Pressure Balance TypeTunneling Machine

1.3 Slurry Type (Fig.1.5)

Slurry type tunneling machine cut the groundwith a rotary cutter head. The cutter chamberis filled with pressurized slurry mix tostabilize the face of the tunnel. The slurrymix is circulated through pipes to transport itto a slurry treatment plant where theexcavated muck is separated from slurry mix.The excavated muck is discharged throughpipes and the slurry is circulated back to thecutter head for re-use. The slurry typemachine consists of the following threecomponents:

i ) A rotating cutter head forexcavating ground

ii) A slurry mixer for the production ofslurry mix with desired density andplasticity

iii) Slurry pumps to feed/discharge,circulate and to pressurize slurry mix

iv) Slurry treatment plant to separateexcavated muck from slurry

Cutter head Cutter driving motor

Bulkhead

Cutter chamber

Slurry feed pipe

Slurry discharge

Fig. 1.5 Slurry Type Tunneling Machine

Page 15: Recommendations ITA TBM

I-5

2 INVESTIGATIONS OF EXISTINGCONDITIONS ANDAPPLICABILITY OF TBM

2.1 Site Investigations

Site investigations are conducted to obtainbasic data necessary for determining theproject scale, selection of a tunnel route andits alignment, applicability of TBMs, and itsenvironmental impact, and for planning,designing and construction of TBM tunnels.Results of the investigations are also used foroperation and maintenance of TBM. Themajor items of investigation are indicated inthe following subsections.

2.1.1. Existing site conditionsExisting site conditions along the proposedtunnel route are investigated to survey thefollowing site conditions

i) Land use and related property rightsii) Future land use planiii) Availability of land necessary for

constructioniv) Traffic and the type of the roadsv) Existing rivers, lakes and oceanvi) Availability of power, water and

sewage connectionsResults of the investigation are mainly usedfor determining the tunnel route, itsalignment, locations and areas of accesstunnels and temporary facilities.

2.1.2. Existing structures and utilitiesExisting structures and utility lines near thetunnel are investigated for their futurepreservation and for securing the safety ofTBM tunneling.

i) Existing surface and undergroundstructures

ii) Existing utilitiesiii) Wells in use and abandonediv) Remains of removed structures and

temporary structures

2.1.3. Topography and geologyTopographical and geological conditions arethe most important factors affecting the TBMdesign and construction. In particular, thefollowing items should be investigated byfield survey, boring, etc.

i) Topographyii) Geological structureiii) Ground conditionsiv) Groundwater

2.1.4. Environmental impactEnvironmental impact analysis of the tunnelconstruction should be carried out to selectand design construction methods thatminimize the environmental impacts to theexisting ecosystem.

i) Noise and vibrationii) Ground movementiii) Groundwateriv) Oxygen deficient air and hazardous

gas such as methane gasv) Chemical groutingvi) Discharge of excavated muck

2.2 Applicability of TBMs

Three types of excavation methods, drillingand blasting, TBM for hard rock, and TBMfor soft ground, are compared in terms oftunnel dimensions, geological conditions andenvironmental impacts, and are shown inTable 2.1. The shaded portions of this tableindicate the application of TBMs for softground.Among the soft ground TBMs, the mechanicalexcavation type, earth pressure balance typeand slurry type is compared in Table 2.2 interms of their applicability to various types ofsoft ground. This table also indicates theitems that should be taken into considerationwhen applying TBM to soft ground. .As indicated in Table 2.2, earth pressurebalance and slurry types are suitable foralluvial deposits that generally are not self-standing. Slurry type is effective for drivingthrough grounds with high groundwaterpressure, such as those under river or seabedbecause the stability of tunnel face can bemaintained by properly mixed and pressurizedslurry mix. On the other hand, earth pressurebalance type is not suitable for grounds withhigh groundwater pressure because it isdifficult to maintain the pressure balancedagainst ground water pressure due to theopening for the soil discharging screwconveyor.

Page 16: Recommendations ITA TBM

I-6

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com

ene

cess

ary.

It is

not

sui

tabl

e in

are

a w

here

wea

kgr

ound

or

wat

er in

flow

will

be

freq

uent

ly e

ncou

nter

ed.

App

licab

leSe

eTa

ble.

2.2

Geo

logi

cal

Con

ditio

ns

Soil

Not

app

licab

leN

ot a

pplic

able

Mos

t sui

tabl

eSe

eTa

ble

2.2

Env

iron

men

tal

Con

ditio

nsN

oise

and

Vib

ratio

n

Due

to n

oise

and

vib

ratio

n, it

is n

otsu

itabl

e in

the

vici

nity

of

hous

es a

ndim

port

ant s

truc

ture

s.A

sup

plem

enta

ry m

etho

d is

nec

essa

ryto

red

uce

the

effec

ts o

f no

ise

and

vibr

atio

n.

Com

pare

d to

the

drill

ing

and

blas

ting

ther

e is

less

effe

ct o

f no

ise

and

vibr

atio

n to

the

hous

es a

nd im

port

ant

stru

ctur

es.

The

re is

less

effe

ct o

f no

ise

and

vibr

atio

n to

the

hous

es a

nd im

port

ant

stru

ctur

es th

an o

ther

exca

vatio

nm

etho

ds.

Page 17: Recommendations ITA TBM

I-7

Tabl

e 2.2

App

licab

ility

of

TB

Ms

to

Sof

t Gro

und

Con

diti

ons

Ope

n ty

peC

lose

d t

ype

Ear

th

pres

sure

ba

lanc

e ty

peT

BM

type

Gro

und

cond

ition

N-v

alue

wat

er c

onte

ntor

perm

eabi

lity

Mec

hani

cal ex

cava

tion

type

Ear

th

pres

sure

ty

peH

igh -

dens

ity s

lurr

y ty

peSl

urry

type

Allu

vium

cla

y

0 –

530

0% –

50%

s-F

ace

stab

ility

-Gro

und

settl

emen

tl

-Diff

icul

ty

in ex

trem

ely

wea

k cl

ay-V

olum

e co

ntro

l of

disc

harge

d

soil

_-E

arth

pre

ssur

e is

mor

esu

itabl

e.s

-Diff

icul

ty

In ex

trem

ely

wea

k cl

ay-S

lurr

y s

pout

ing

onsu

rfac

e-I

ncre

ase o

f se

cond

ary

slur

ry t

reat

men

t p

lant

Dilu

vium

cla

y7

– 20

W <

50%

l-E

xist

ence

of

wat

erbe

arin

g s a

nd-B

lock

a ge

in slit

cha

mbe

rl

-Liq

uidi

ty o

f so

il-V

olum

e c

ontr

ol

ofdi

scha

rged

soi

l_

-Ear

th p

ress

ure

is m

ore

suita

ble.

l-I

ncre

ase

of s

econ

dary

slur

ry t

reat

men

t pl

ant

Soft

roc

k(m

udst

one)

> 5

0W

< 2

0%l

-Exi

sten

ce o

f w

ater

bear

ing

sand

-Wea

r of

cut

ter

bits

_

-Ear

th p

ress

ure

with

slur

ry i

s m

ore

suita

ble

whe

n t

here

is w

ater

bear

ing

san

d.

_-S

uita

ble w

hen

the

re is

wat

er b

eari

ng s

and

_-S

uita

ble w

hen

the

re is

wat

er b

eari

ng

san

d

Loo

se s

and

5 –

3010

-2 –

10-3

(cm

/s)

x-U

nsta

ble f

ace

s-

Con

tent

s of

fin

e

part

icle

sl

-Hig

hly-

advan

ced

exca

vatio

n co

ntro

ll

-Hig

hly-

advan

ced

exca

vatio

n c

ontr

ol-Q

ualit

y co

ntro

l of

slur

ry

solu

tion

Den

se s

and

> 3

010

-3 –

10--

4

(cm

/s)

s-F

ace

stab

ility

-Gro

undw

ater

lev

el,

perm

eabi

lity

s-

Con

tent

s of

fin

epa

rtic

les

l-W

ear

of

cutte

r bi

ts-D

osag

e of

add

itives

l-Q

ualit

y co

ntro

l o

fsl

urry

so

lutio

n

Sand

grav

el

> 3

010

0 – 1

0-2

(cm

/s)

s-F

ace

sta

bilit

y-G

roun

dwat

er l

evel

,pe

rmea

bilit

ys

- C

onte

nts

of f

ine

part

icle

sl

-Wea

r o

f c

utte

r bits

-Dos

age

of

add

itives

l

-Run

ning

aw

ay o

f sl

urry

-Grav

el

crus

her

-Flu

id tr

ansp

orta

tion

syst

emSa

nd a

nd g

ravel

With

bou

lder

s>

50

100 –

10-1

(cm

/s)

x

-Fac

e st

abili

ty-B

ould

er c

rush

er-W

ear

of

cutte

r b

its

and

face

s

- C

onte

nts

of fin

e pa

rtic

les

-Wea

r of

cutte

r bi

ts a

nd f

ac-B

ould

er c

rush

er-B

ould

er d

iam

eter

for

screw

-con

veye

r

l

-Wea

r of

cutte

r bi

ts-B

ould

er c

rush

er-B

ould

er dia

met

er fo

rsc

rew-c

onve

yer

s

-Run

ning

aw

ay o

f sl

urry

-Bou

lder

cru

sher

-Flu

id tr

ansp

orta

tion

syst

em

App

licab

ility

for

grou

ndC

ondi

tion

chan

ges

It is

impo

ssib

le to

cha

nge

exca

vatio

n s

yste

m.

App

licab

leA

dditiv

e

inje

ctio

n eq

uipm

ent

beco

mes

ne

cess

ary.

App

licab

leIn

gen

eral

, it i

s w

idel

yap

plic

able

for

var

ious

so

ilco

nditi

ons.

App

licab

leIn

gen

eral

, It i

s w

idel

yap

plic

able

for

var

ious

so

ilco

nditi

ons.

Not

e:l

App

licab

le,

s C

onsi

dera

tion re

quir

edx

Not

appl

icab

leIt

emst

o c

onsi

der w

hen a

pply

ing

In c

ase o

f x,

rea

sons

for n

ot ap

plic

able

Page 18: Recommendations ITA TBM

I-8

3 TUNNEL BORING MACHINE(TBM)

3.1 Machine Specifications

3.1.1. Essential parts of TBMTBMs are normally manufactured in drum-shaped steel shield equipped inside withexcavation and segment erection facilities.The essential parts of the machine include thefollowing items:

i) Rotary cutter head for cutting theground

ii) Hydraulic jacks to maintain aforward pressure on the cutting head

iii) Muck discharging equipment toremove the excavated muck

iv) Segment election equipment at therear of the machine

v) Grouting equipment to fill the voidsbehind the segments, which is created bythe over excavation.

3.1.2. Structure of TBMTBM is composed of the steel shell (so calledthe shield) for protection against the outerforces, equipment for excavation of soil andfor the installation of the lining at the rear.The power and control devices are mountedpartly or totally on the trailing car behind themachine, depending on the size and structureof the machine. Steel shell, made of the skinplate and stiffeners, is composed of threeportions; hood, girder and tail portion (seeFig. 3.1).

In case of the closed type machine, hood andgirder portions are separated by a bulkhead.The soil excavated by the cutter head is takeninto the mucking device through the hoodportion. In some cases, man-lock is installedat the bulkhead in order to change the cutterbits or to remove obstacles under thepneumatic pressure.

For manual type, breasting is provided at thehood portion. The reaction force is supportedby the girder portion where the thrustingdevices are installed.The tail portion of the machine is equippedwith erector of the segments. Tail seal forwater stop is inserted between the skin plateand the segment ring.In case of the articulating system, the girderportion is made flexible by dividing theportion into two or more bodies with pins andjacks. Such flexible separation of the body isadopted to allow a smooth turn along thecurved alignment of the tunnel with differentdiameters of the machines, degrees ofallowance of over cutting and under varioussoil conditions,.When two tunneling machines are connectedunderground, the alignments and the relativepositions of the two machines have to becarefully monitored and adjusted. The finalconnection normally requires some soilimprovement work such as ground freezing,or else with extendable cutter head or hoodequipped on either one of the machines.

Fig. 3.1 Components of Tunneling Machine

Page 19: Recommendations ITA TBM

I-9

3.1.3. Types of TBMs for soft groundAs described in the previous section, TBMsfor soft ground are classified into three types;earth pressure type, slurry type andmechanical type. These three types of TBMsare summarized in Fig 3.2. Before thosethree types were developed, other types of

TBMs such as the open type, blind type,manual type, and half-mechanical type wereused for soft ground. The open type TBM isnow mostly replaced by closed type for softground tunneling.

Fig. 3.2 Type of TBM for Soft Ground

3.1.4. Selection of TBMCareful and comprehensive analysis should bemade to select proper machine for soft groundtunneling taking into considerations itsreliability, safety, cost efficiency and theworking conditions. In particular, thefollowing factors should be analyzed:

i) Suitability to the anticipatedgeological conditions

ii) Applicability of supplementarysupporting methods, if necessary

iii) Tunnel alignment and lengthiv) Availability of spaces necessary for

auxiliary facilities behind the machine andaround the access tunnels

v) Safety of tunneling and other relatedworks.

Fig. 3.3 indicates a flow chart for selectingTBM for soft ground. In selecting the type ofTBM, it is important to consider geological andgroundwater conditions that affect the stabilityof the tunnel face. Geological condition along the tunnel route isa primary factor to be considered for selecting

the type of machine. Particularly, the degree ofconsolidation of the ground and the size ofgravel and boulders in the soil should bethoroughly investigated. Table 3.1 shows thegeneral relationship between the closed type oftunneling machine and soil conditions. In acase where a tunnel is very long or is undercomplex geological conditions, uniform layerscould not be expected throughout the entirelength of the tunnel. In such case, a tunnelingmethod is selected based on the geologicalcondition prevailing throughout the tunnel.Special attention should be paid to thefollowing local geological conditions: i) Soft clayey soil that is sensitive and easy tocollapse ii) Sand and gravel layers with high watercontents iii) Layers which contain boulders iv) Layers which may contain driftwood orruins v) Strata which are composed of both soft andhard layers

Slurry type is easy to be automaticallycontrolled and is the most advanced excavation

(Tunnel face stabilization)

Excavate soil + face plate

Excavate soil + spokeplate stabili ingExcavate soil + additives + face plate

Excavate soil + additives + spoke

Slurry + face platestabilizingSlurry + spoke

Bulkhead

Hood

Breasting

Hood

Breasting

Face plate

Spoke

Earth pressure

High-density slurry

Earth pressure type

Slurry type

Blind type

Manual

Half mechanical

Mechanical

Fully open

Partially open

Open

Closed

TBM

Page 20: Recommendations ITA TBM

I-10

method for soft ground tunneling because of itsreliability, safety and the minimum disturbanceto surrounding ground.Both earth pressure balance type and slurrytype generally does not require supplementarysupporting methods under ordinary conditions.The supplementary methods should beconsidered, however, for tunneling at starting

and arrival area where the face of the tunnel isdifficult to be stabilized. Also, somesupplementary methods such as chemicalgrouting, ground freezing, pneumatic pressureand boulder crushing are required to drivethrough grounds with boulders or gravel, underthin overburden or any other special conditions.

Fig. 3.3 Flow Chart for Selecting TBM for Soft Ground

Site Investigation

Investigation for Route SelectionConditions of the Plan, Geological Conditions, Conditions of Construction, etc.

Prel

imin

ary

Inve

stig

atio

n

Investigation for ConstructionFace Stability, Ground Settlement, Environmental Preservation, etc.

Geology,

Bas

ic I

nves

tigat

ion

FaceYes No

Mechanized Excavation TypeEarth Pressure Balance Type

Slurry Type

Investigation of Additional Countermeasures

Investigation of Ground Settlement

Selection of Construction Method

Comparison of TBM Type

Selection of TBM Type

Det

aile

d In

vest

igat

ion

Page 21: Recommendations ITA TBM

I-11

Tabl

e 3.1

Rel

atio

nshi

p bet

wee

n C

lose

d T

ype

Tunn

elin

g M

achi

ne a

nd S

oil C

ondi

tion

s

Ear

th p

ress

ure b

alan

ce ty

peE

arth

pre

ssur

e typ

eH

igh-

dens

ity sl

urry

type

Slur

ry ty

peTy

pe o

f mac

hine

Soil

cond

ition

sN

-val

ueSu

itabi

lity

Che

ck p

oint

Suita

bilit

yC

heck

poi

ntSu

itabi

lity

Che

ck p

oint

Mol

d0

x_

sse

ttlem

ent

sSe

ttlem

ent

Silt,

Cla

y0

– 2

l_

l_

l_

Sand

y si

lt0

– 5

l_

l_

l_

Allu

vial

clay

Sand

y cl

ay5

– 10

l_

l_

l_

Loa

m, C

lay

10 –

20

sJa

mm

ing

byex

cava

ted

soil

l_

l_

Sand

y lo

am15

– 2

0s

ditto

l_

l_

Dilu

vial

clay

Sand

y cl

ayO

ver 2

5s

ditto

l_

l_

Solid

cla

ySo

lid c

lay

( m

uddy

pan

)O

ver

50s

ditto

sW

ear

of b

its

Wea

r of

bit

Sand

with

silty

cla

y10

– 1

5l

_l

_l

_

Loo

se sa

nd10

- 3

0s

Con

tent

of c

laye

yso

ill

_l

_Sa

nd

Com

pact

sand

Ove

r 30

sdi

ttol

_l

_L

oose

gra

vel

10 –

40

sdi

ttol

_l

_

Com

pact

gra

vel

Ove

r 40

sH

igh

wat

erpr

essu

rel

_l

_

Gra

vel w

ith c

obbl

est

one

_s

Jam

min

g of

scr

ewco

nvey

orl

_s

Wea

r of

bit

Gra

vel

Cob

ble

ston

eL

arge

gra

vel

Cob

ble s

tone

_s

Wea

r of

bit

sW

ear

of b

its

Cru

shin

g dev

ice

l :n

orm

ally

appl

icab

les:

appl

icab

le w

ith s

uppl

emen

tary

mea

nsx

:not

suita

ble

Page 22: Recommendations ITA TBM

I-12

3.2 Orientation and operation of machine

3.2.1. Excavation Control SystemSince the closed type machine was developed,tunnel excavation has been mostly controlledby computerized system rather than manually.In addition, various supporting systemsnecessary for tunneling operation requiresophisticated controlling system. A real timecomputerized system equipped with varioussensors is developed for tunneling, in whichorientation and operation of machine,excavation, backfill grouting and operation ofauxiliary facilities are controlled by acentralized computer system. The systemrealized accurate alignment, excavation controlthat maintains the stability of the face of thetunnel, and minimized the disturbance of thesurrounding ground. For slurry type tunnelingmachine, operation of pumps and valves forslurry transportation is computerized based onthe data fed by pressure gauges, flow metersand other measuring devices for fluidtransportation. Thus, steady pressure of slurryis maintained throughout the tunnelingoperation.

In the near future, all operation of the machinewill be entirely controlled by computerizedsystem from above ground.

3.2.2. Direction Control and MeasurementSystemAutomatic direction control system has beenput to practical use that utilizes survey dataobtained by real time measurement deviceinstead of the conventional transit-level survey.The system consists of measurement anddirection control systems, and comprises offour functions; survey, monitor, analysis andcontrol. The measurement system utilizes laserbeam (laser, infrared or diode) or gyrocompass,and measures the location of the machine inthree-dimensional coordinates and its attitude(pitching, rolling and yawing).

Direction of the machine is normally controlledby jacks that introduce proper thrust force androtation moment. Each jack on a cutter disk iscontrolled by a computerized system based onthe target amount of thrust and the direction ofmachine. In the process of determining theamount of thrust required for each individual

jack, a mathematical theory of “fuzzy controltheory” has been applied based on the dateaccumulated through the past performance ofthe machine. Recent automatic directioncontrol system realizes accuracy of plus orminus 30 mm both horizontally and vertically.

3.3 Cutter Consumption

3.3.1. Bit types and ArrangementThere are several types of bits for TBM, suchas teeth bit, peripheral bit, center bits, gougingbit, wearing detection bit, etc. Bits aregenerally made by steel or hard chip alloy thatis highly wear resistant. Selection of materialand types of bits is made based on the groundconditions, excavation speed andlength of the tunnel. Arrangement of bitson the cutter head is decided based onconstruction conditions, past experiencein similar geology, cutting depth and thenumber of passes of rotating bits.

3.3.2. Wear of BitGenerally, the amount of wear of bits isproportional to the product of number of passesof rotating bits and length per pass, and isinfluenced by ground conditions and otherfactors such as type of machine, geology,material and arrangement of the bits on a cutterhead. The amount of wear can be estimated bythe following formula;

d =(K.π.D.N.L)here, d: amount of wear (mm) K: wear coefficient (mm / km) D: distance between the center of cutterdisk and bit (m) N: number of revolution of cutter disk perminute (rpm) L: excavation distance (m) V: rate of excavation (mm / min)

The wear coefficient, K, above is given bymanufacturers based on the pressure applied tobits, the rotating speed, geological conditions,number of passes and material of bits to beused.

3.3.3. Long Distance ExcavationSometimes, a tunneling machine is required todrive through entire length of tunnel whenaccess tunnels for installation of two or more

Page 23: Recommendations ITA TBM

I-13

machines cannot be constructed due to the lackof land available. In that case, the tunnelingmachine, especially the cutting bit and tail seal,is required to be highly durable. For higher durability of the bits, new chippingmaterial such as hard chip alloy has beendeveloped, which are two or three timesdurable than those of conventional material.Bits can be changed from inside the TBM.Durability of tail seals and the method ofchanging them are being improved as well.

3.4 Ground Support and Lining

3.4.1. Design of LiningThe linings of the tunnel must withstand thesoil and water pressure acting on the tunnel.Primary tunnel lining is usually constructed byprefabricated concrete segments erected aroundthe periphery of the tunnel. Those segmentsare connected each other to form circular ringswhich are installed side by side continuously toform a cylinder. The second lining, whenrequired, is normally constructed by in-situconcrete.

Usually primary lining is designed as a mainstructural member against the final load,because the secondary lining is installed long

after the erection of segments. Therefore, therole of the secondary lining is mostly notfor the main structural member, but forthe supplementary member for waterproofing, anticorrosion, etc. Secondarylining is omitted to save costs when theprimary lining is watertight enough or theground conditions are favorable.

For the design of the segment, several loadsand their combination should be considered(see Table 3.2). Temporary loads that varyduring the construction such as thrust force byjacks and grouting pressure should be alsotaken into consideration.

The effects of joints between segments andrings should be carefully assessed whendesigning segment lining. As several segmentsare pieced together to produce a ring, the ringmay not deform uniformly against thesurrounding loads due to weakness at segmentjoints. The same can be said to the jointsbetween rings. Staggered arrangement is madeto reduce these effects of the joints.

Under present design method, segment ringassumes to be a uniform flexural ring, a multi-hinged ring or a ring with rotational springs.

Table 3.2 Loads on Segments

Main load vertical and horizontal earth pressurewater pressure

dead loadsurcharge loadground reaction

Secondary load internal loadtemporary load during execution

seismic loadspecial load Influences of adjacent tunnel

of adjacent structuresof ground settlement others

3.4.2. Types of SegmentAs the cost of segments shares significantportion of total tunneling cost, type of segmentshould be carefully selected from bothengineering and economical points of view.Segments are classified into several types;reinforced concrete (RC), steel, cast iron(ductile), composite, and others.

Reinforced concrete prefabricated segmentsare most commonly used for tunnels driven byTBMs. Reinforced concrete segment is anexcellent lining member with highcompressive strength against both radial andlongitudinal forces. It also has high rigidityand water tightness. On the other hand, it isheavy and has less tensile strength and morefragile than steel ones. Therefore, extremecare should be taken to the removal of forms

Page 24: Recommendations ITA TBM

I-14

during fabrication and to the erection duringconstruction in order to avoid possibledamages to segments, especially to theircorners. Rectangular shaped segments arecommonly used, but hexagonal or othershapes are also produced. They can be eithersolid or box type.

Steel segment is flexible and is relatively lightand easy in handling. Because of theflexibility of steel segment, they should not besubjected to high thrusting force of jacks orgrouting pressure to avoid buckling orunnecessary deformation. When the secondlining is omitted, proper anticorrosionmeasures should be taken.

Cast iron (ductile) segment is produced withprecise dimensions and therefore can beerected with good water tightness. Because ofits strength and durability, it is commonlyused at locations under heavy loads or forreinforcing tunnel openings.

In addition to above three types of segments,

various types have been used or proposed,such as composite segments (steel and RC,steel and plain concrete), flexible segment thatallows certain degree of deformation causedby earthquake or uneven ground settlement.Also, there are several types of radial andlongitudinal segment joints such as bolt,cotter, pin and pivot, knuckle and other jointtypes.

3.4.3. Fabrication of SegmentFabrication of segments has to be carried outunder strict quality control to ensurecompliance with specified dimensions andstrength. Automated fabrication of segmentsis desired that provide adequate qualitycontrol to ensure structural integrity andprecise dimensions of segments.Table 3.3 provides allowable stresses ofconcrete for pre-fabricated reinforcedconcrete segment.

Table 3.4 provides typical dimensions ofsteel and concrete segments.

Table 3.3 Allowable stresses of concrete for pre-fabricated concrete segments

Allowable stress (N/mm)

Design compressive strength 42 45 48 51 54

Bending compressive stress 16 17 18 19 20Shearing stress 0.71 0.73 0.74 0.76 0.77Bonding stress to deformed re-bar 2.0 2.1 2.1 2.2 2.2Bearing stress (overall load) 15 16 17 18 19

Page 25: Recommendations ITA TBM

I-15

Table 3.4 Typical Dimensions of Segments (mm)

Steel Segment Concrete SegmentOuter Diameter Width Thickness NO/Ring Width Thickness NO/Ring1,800 _ 2,000 750 75

1006 900 100

1255

2,150 _ 2,550 9001,000

100125

6

2,750 _ 3,350 9001,000

125150175

6

9001,000

100125150

5

3,550 _ 4,050 9001,000

125200225

7

4,300 _ 4,800 9001,000

150175

7

9001,000

125150175200

6

5,100 _ 5,700 9001,000

175200225

7

6,000 9001,000

200225

7

9001,000

175200225250275300

6

6,300 _ 6,900 9001,000

250275

7 9001,000

250275300

7

7,250 _ 8,300 9001,000

300325350

8 9001,000

275300325350

8

3.4.4. Erection of SegmentsThe process of primary lining consists oftransportation and erection of segments.Segments are usually transported through thetunnel by cars on rails. Automatictransportation system of segments is used torecent projects that transport segments from adepot above ground to the rear end of themachine through access shaft and tunnel.

The erection of segments is done by anerector at the rear room of the machine. Thesegment erector is equipped with gripping,shifting, rotating and setting devices.Longitudinal joints of segment rings arenormally made manually.

3.5 Auxiliary Facilities

Generally, tunneling operation by TBMconsists of cutting ground by cutter head,jacking to push machine forward, mucktransportation, segment erection and groutingof voids behind segments. Auxiliary facilitiesthat are typically required throughout thisoperation are shown in Table 3.5.Common facilities are gravel treatment plant,grouting facilities, segment depot andtreatment facilities. For the discharge ofexcavated muck, different types of facilitiesare required depending on the type oftunneling machines as follows.

Page 26: Recommendations ITA TBM

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3.5.1. Earth pressure balance typemachineThe excavated muck is removed from thecutter chamber by a screw conveyor and sentout by mucking car or belt conveyor. Forsmall diameter tunnels where working spaceis quite limited, the excavated muck is mixedwith plasticizer and pumped out through thepipe. For these operations, additive mixingplant, a screw conveyor and belt conveyor ormucking cars are required.

3.5.2. Slurry type tunneling machineSequence of discharging the excavated muckfor this type of machine consists of; (i)pouring slurry to the cutter chamber while thesoil is excavated and the machine is pushedforward, (ii) mixing excavated soil with slurryand pumping the slurry mix from the cutterchamber to a treatment plant where the slurrymix is separated into soil and slurry, (iii)discharging the separated soil out to thedisposal area and circulating the slurry backto the tunnel face for reuse. Auxiliaryfacilities required for these operations areslurry mixer, feed and discharge pumps andpipes, and slurry treatment plant.

Table 3.5 Auxiliary Facilities

Earth pressure balance type Slurry type- Segment pool and transportation facilities for segments and materials- Central control room- Gravel treatment facilities, such as crushing device- Grouting facilities for back fill- Belt conveyor, mucking cars or pumps- Additive mixing plants

- Slurry transport facilities, such as slurrypumps and pipes.

- Slurry treatment facilities, such ascentrifugal classifier and filter plant

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4.3 Size of TBM

4.3.1. Weight

Fig. 4.5 Diameter and weight of TBM (EPB, Slurry)

4.3.2. Length/Diameter (L/D)

Fig. 4.6 Diameter and length/diameter (L/D) of TBM

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APPENDIX: TBM PERFORMANCE INHARD ROCK

A-1 General

The following prognosis model is a summaryof “Project Report 1-94, Hard Rock TunnelBoring”, published by University ofTrondheim, The Norwegian University ofScience and Technology, NTH Anleggsdrift.

The prognosis model is based on job sitestudies and statistics from 33 job sites with 230km of bored tunnels in Norway and othercountries. Data have been carefully mapped,systematized and normalized and the presentedresults are regarded as representative for wellorganized tunneling. It should be noted thatthe prognosis model is valid for parametervalues in the normal range. Extreme valuesmay, even if they are correct, not fit the modeland give incorrect estimates.

The prognosis model has been developedcontinuously since 1975 and has in the periodup till now been through several phases and

adjustments in accordance with increasedknowledge and improvements of TBMs,auxiliaries and methods. The model is todayconsidered as a practical and useful tool forpre-calculation of time consumption and costsfor TBM bored tunnels in hard rock. Themodel is based on the use of TBM, Open type.

A-2 Advance

A-2.1 Rock Mass Properties1. DRILLING RATE INDEX, DRI: Indexrelated to the properties of the rock mass.Together with Fracturing, DRI is the rock massfactor that has the major influence onPenetration Rate.DRI is calculated from two laboratory tests,- the Brittlenes Value S20- Sievers J-Value SJThe two tests give measures for the rock’sability to resist crushing from repeated impactsand for the surface hardness of the rock.Recorded Drilling Rate Indexes for some rocktypes are shown in Fig. A.1.

Fig. A.1 Recorded Drilling Rate Index for various rock types

2. CUTTER LIFE INDEX, CLI: Cutter LifeIndex is calculated on the basis of Sievers J-Value and the Abrassion Value steel. ( AVS.)

CLI expresses the lifetime in boring hours forcutter rings of steel on TBM. Recorded CLIfor some rock types are shown in Fig.A.2

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Fig.A.2 Recorded Cutter Life Index for various rock types

3. FRACTURING: The most importantpenetration parameter for tunnel boring. In thiscontext, fracturing means fissures and jointswith little or no shear strength along the planesof weakness. The less the distance between thefractures is, the greater the influence on thepenetration rate. Rock mass fracturing ischaracterized by degree of fracturing (type andspacing) and the angle between the tunnel axisand the planes of weakness.

a) JOINTS in this respect are fractures that canbe followed all around the tunnel profile.

b) FISSURES are non-continuous fractureswhich can be followed only partly aroundthe tunnel profile.

c) FRACTURING is recorded in CLASSESwith reference to the distance between theplanes of weakness. The classes are shown inFig. A.3. Recorded fracturing for some rocktypes are shown in.

Fig. A.3 Fracture classes with corresponding distance between planes of weakness

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Fig. A.4 Recorded degree of fracturing for various rock types

d) FRACTURING FACTOR, Ks combines theeffect of the fracturing class and the anglebetween tunnel axis and planes of weakness.See Fig.A.5. The factor Ks is used in aformula for calculation of penetration rate.

e) EQUIVALENT FRACTURING FACTORexpresses the rock mass properties as theFracturing Factor Ks adjusted for DRI-value.See Fig.A.5. KEQV = Ks x KDRI

Fig. A.5 Fracturing factor, Correction factor for DRI≠49

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A-2.2 Machine Parameters1. BASIC CUTTER THRUST: (MB) The grossthrust of the TBM divided by number ofcutters, N. Thus, for practical calculatingpurpose the CUTTER THRUST in this modelmeans the average thrust of all the cutters onthe cutter head (kN/cutter). The friction

between TBM and rock mass is disregarded.Recommended max. gross average thrust forTBMs with different diameters and cutterdiameters are shown in Fig. A.6. Forcalculation of penetration the cutter diameterand cutter spacing must be taken into account.

Fig. A.6 Recommended max. gross average per disc

2. CUTTER SPACING: The averagedistance between the cutter tracks on the face =Diameter of TBM /2N (N= number ofcutters)._CUTTER SPACING is normallyabout 70 mm.3. CUTTER HEAD R.P.M.: Revolutions per.

Minute. Cutter head r.p.m. is inverseproportional to the cutter head diameter. This isin order to limit the rolling velocity of theperipheral cutters. Cutter head r.p.m. asfunction of TBM diameter is shown in Fig. A.7.

Fig. A.7 Cutterhead r.p.m. as function of TBM-diameter

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4. INSTALLED POWER ON CUTTERHEAD: (kW) The rated output of the motorsthat are installed to give the cutter head itstorque. The rolling resistance and thus thetorque demand increases with increasing netpenetration. The available torque may thereforebe the limiting factor when the penetration ishigh and/or the TBM is boring in veryfractured rock. See 3) (3) TORQUE -DEMAND below.

A-2.3 Other Definitions1. BASIC PENETRATION RATE: BasicPenetration Rate (i) in mm/rev as a function ofequivalent thrust and equivalent fracturingfactor is shown in Fig. A.8. For cutterdiameters and average cutter-spacing differentfrom _=483 mm and 70 mm respectively theequivalent thrust is given by the formula: MEQV

= M x x KDX x KA (kN/cutter)Fig. A.9 and Fig. A.10 give correction factorKd for cutter diameters different from 483 mmand factor KA for cutter spacing.

Fig. A.8 Basic penetration for cutter diameter = 48.3 mm and cutter spacing = 70 mm

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Fig. A.9 Correction factor for cutter diameter≠483 mm

Fig. A.10 Correction factor for average cutter spacing≠70 mm

2. NET PENETRATION RATE: Netpenetration rate (I) is a function ofbasic_penetration and cutter head r.p.m.I = i x r.p.m. x (60/1000) (m/hr)3. TORQUE DEMAND: For calculated highnet penetration or when the rockis_very_fractured, one must check that the

installed power on the cutterhead givessufficient torque to rotate the cutterhead. If notthe thrust must be reduced until the requiredtorque is less than the installed capacity.Necessary torque is given by the followingformula:

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TREQ. =0.59 x rTBM x NTBM x M x kc (kNm)0.59 = Relative position of the average cutter on the cutterhead.RTBM = cutterhead radius.NTBM = number of cutters on the cutterhead.M = Average thrust pr, cutter.Kc = cutting coefficient (for rolling resistance) kc = Cc x i 0.5

Cc is a function of cutter diameter and is found from Fig. A.11.

Fig. A.11 Cutting constant Cc as a function of cutter diameter

4. Other Limitations to Advance RateBesides limitations due to available torque, thesystem’s muck removal capacity may be alimiting factor, particularly for large diametermachines. When boring through marked singlejoints or heavy fractured rock, it may benecessary to reduce the thrust due to too highmachine vibrations and very high momentarycutter loads.

A-2.4 Gross advance rateTHE GROSS ADVANCE RATE is given inmeters per week as an average for a longerperiod. Gross advance rate depends on netpenetration rate, machine utilization and thenumber of working hours during the week.Machine utilization is net boring time inpercent of the total tunneling time. Totaltunneling time includes: Boring TB (Dependson net penetration rate)

- Regripping TT (Depends on stroke length,normally 1.5-2.0 m. As an average 4-5minutes.)

- Cutter change and inspection Tc (Dependson cutter ring life and net penetration rate.Time needed for cutter change may varyfrom 30 to 60 minutes per cutter.)

- Maintenance and service of TBM, TTBM,and back-up equipment TBACK (Timeconsumption for maintenance and repairdepends on net penetration rate asindicated in Fig. A.12.)

- Miscellaneous TA (Miscellaneous includenormal rock support in good rockconditions, waiting for transport, tracks orroadway, surveying or moving of laser,water, ventilation electric cable, cleaning,other things like travel, change of shiftetc.) TA as hours per km is indicated inFig. A.12.

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Fig. A.12 Maintenance as function of net penetration rate

A-2.5 Additional Time ConsumptionEstimation of time consumption for a tunnel isbased on weekly advance rate, estimated on thebasis of net penetration rate and total utilizationof the TBM. In addition, extra time must beadded for- assembly and disassembly of TBM and

back-up equipment in the tunnel- excavation of niches, branches, dump

stations etc.- rock support in zones of poor quality- additional time for unexpected rock mass

conditions- permanent rock support and lining work- downtime due to major machine

breakdowns- dismantling of tracks, ventilation, invert

cleanup etc.

Example of application

Geometrical conditions:Tunnel diameter: f = 4.5 mTunnel length: L= 3200 m

Geological conditions:Type of rock: Mica Schist

Drilling Rate Index: DRI= 60Degree of fracturing: St IIAngle between tunnel axisand planes of weakness: 45Fracturing factor. ks = 1.40

Machine parameters:TBM diameter: f = 4.5 mCutter diameter: 483 mmGross thrust pr. cutter: Fig. A.6

290 kN/cutterCutterhead r.p.m.: Fig. A.7

11.1 rev./min.Number of cutters: 32Average cutter spacing: 70 mmInstalled power: 1720 kW

Net penetration rate:Equivalent thrust: Fig. A.9 and Fig. A.10 MEQV = 290 x 1.00 x 0.975 = 283 kN/cutterBasic penetration: Fig. A.8 i = 8.40 mm/revNet penetration:

8.40 x 11.1 x 60/1000 = 5.59 m/hour

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Torque check:Cutter constant: Fig. A.11

Cc = 0.034Cutting coefficient: kc = 0.034 x 8.400.5 = 0.0985Necessary torque:

Necessary power: PN = 1213 x 2π x 11.1/60 = 1410 kW

A-3 Cutter Consumption

The cutter ring life depends mainly on thefollowing factors:

1. Rock mass properties:- CUTTER LIFE INDEX (CLI), see A-2, 1.

(2)- Content of abrasive minerals in the rock

2. Machine parameters:- Cutter diameter- Cutter type and quality- Cutter head diameter and shape- Cutter head rpm- Number of cutters

The cutter ring life, in boring hours, isproportional to the Cutter Life Index. (CLI)Fig. A.13 shows the basic cutter ring life as afunction of CLI and cutter diameter.Corrections must be made for varyingcutterhead r.p.m. Also for TBM diameter asCenter- and Gauge Cutters have a shorterlifetime than Face Cutters. (Fig. A.14).Corrections must also be made for number ofcutters on TBM (Ntbm) deviating from normal(No). Finally correction must be made toquartz-content.(Fig. A.15)

Average life of cutter rings is thus given thefollowing formulas:Cutter ring life in h/c: HH = (H0 x k f _ x k0 xkRPM x kN)/NTBM

Cutter ring life in m/c: Hm = HH x I (I = netpenetration rate)

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Fig. A.13 Basic cutter ring life as function of CLI and cutter diameter

Fig. A.14 Correction Factor for Cutting Ring Life

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Fig. A.15 Correction Factor for cutting ring vs. Quartz Content

A-4 Troubles and Countermeasures

A-4.1 Causes for Trouble.<<Trouble>> is caused by unforeseen incidentsor conditions that may be difficult to tacklewithin estimated tunneling time. Trouble inhard rock boring come from:- geological conditions- reasons related to the TBM itself and/or

from the rest of the machines andinstallation, - and/or trouble come as aconsequence of lack of experience fromsimilar works and general know-how intunneling.

1. Geological Causesa) Water Inflow is always a factor one shall

have in mind. It counts for everythingfrom occasional appearance of smallamounts of water with no practicalconsequences, to total inundation with freeflowing conditions, some times withmaterial outwash and serious tunnelingproblems. If caught unaware, theseproblems are capable of completelydisrupting tunneling activity andinfluencing the time schedules drastically.This is serious to conventional tunneling, -

it may be even worse to TBM-tunnelingwith all the sophisticated electricalinstallations.

Water may come from groundwater, ores,leakage through the overburden from lakes,rivers etc. or even from underground lakes orfrom Artesian wells. Inflow of salt water maybe damaging even in small amounts and callsfor special precautions.It creates a special atmosphere in the tunnelwith damaging effect to the electricalequipment and rust and corrosion to the steelconstruction if not taken care of.

b) Boring in Hard Rock means normally boringin Sound, Solid Rock, and <<open>> TBMsare normally chosen. Nevertheless it is notunusual to meet Faulty Fractured Zones,Unconsolidated Weak Rock, Swelling Ground,Squeezing Ground and very often so calledMixed Faces which means that face consistspartly of hard massive rock and partly offractured rock. Even one single significantfracture may influence the drillability.Consequences to the boring may naturally varyfrom minor problems to the penetration rate tofull stop with TBM stuck in the tunnel.

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Swelling Ground very often comes from theinfluence of special rock materials as so calledswelling clay which starts swelling whenexposed to humidity. It may cause down-falland dangerous conditions. Squeezing Groundis found in tunnels in soft rock with largeoverburdens, and consequently high rockpressure. Rock deformations may in extremecases lead to total closing of the tunnel.

c) Even if TBM- technology and –know how issteadily improving and thus extending theframe as far as the geology and thegeological parameters are concerned, thereare still limits. The drillability is a functionof a number of rock parameters, out ofwhich fracturing and rock hardness are themost important. It is rare to get into rockwhich is so hard and so massive that boringis technically impossible with the mostpowerful TBMs on the market to day, but itmay be a challenge to the economy.

If pre-investigations reveal occurrence of rockwith the above properties it will be a matter ofcalculation to find out if the available TBM isable to do the job, and in case, -what will bethe advance rate and what will be the cost. Theabove calculation model should be usedcarefully in this case since it is based onexperiences from rock with not extremeproperties, but it will normally be goodenough. If the rock shows up unexpectedparameters one might be in trouble if the TBMis too weak, and/or the cutters have insufficientquality.

d) High Temperature Ground is found indifferent parts of the world as for instance inthe Alps, in tropical areas and/or when thetunnel goes with extreme overburden as inmines. The temperature is seldom a realobstacle to the boring itself as long as oil ischosen accordingly and cooling water formotors and cutters are available in sufficientquantities, but rather a challenge to the crew.

e) Combustible gases like methane and dustwith high content of coal are dangerous andmust be taken care of properly.

2. Machine Related TroublesAs is understood from the above a good resultwith respect to advance rates and tunnel-meter-

costs are to a very great extent dependent onthe TBM and the supplementary equipment.The geology related conditions in a tunnel arefixed as such. The result of the tunneling withrespect to advance rate and tunnel-meter-cost istherefore in fact a question of doing the rightchoice of TBM and equipment and to beprepared for conditions as they appear.

The right choice of TBM and supplementaryequipment is not only a question of looking atmachine specifications. It is also a question towhich extent it is possible to utilize the samemachine parameters. It is an experience fromhard rock boring that the TBMs have morepower than can actually be utilized becausecomponents like for instance cutters in practiceare not strong enough.Breakdowns due to Main Bearing failure or dueto failure on other important and expensivecomponents or parts are naturally disastrous totime schedule and costs. (To change a mainbearing may take from four to six weeks,provided the bearing is available.) Downtimecaused by unskilled operation of themachinery, bad maintenance and repair,waiting for supply of spares, bad ventilation,cut in power supply, waiting for muck-transport, cutter change and cutter inspectionshould always be encountered and as far aspossible be avoided or minimized.

A-4.2 Countermeasures1. For trouble caused by water inflow there arebasically two ways to go.- To stop the water before it gets into the

tunnel by Grouting Ahead of the Face forwhich purpose boring equipment has to beinstalled. The equipment should be able tomake a 360°funnel with at least 25 m longholes for grouting.

- To take care of the water when it is in thetunnel by Increased Drainage Capacity.What is the best is depending on theamount of water and where it comes from.If the inflow effects change in groundwater level and/or pressure grouting maybe required. Large inflow of water maycause damage to the machinery, and to theelectrical installation in particular, andprotection of exposed components may berequired.

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2. Countermeasures to unusual and unsoundground depends on the actual caseRock Bolting, Fiber-reinforced Shotcrete aloneor together with Rock Bolts, Grouting or in situCasting with Concrete or may be necessary.The real trouble comes if the equipment is notbuilt for installation of necessary equipment tocarry out the rock support in an efficient way.Fractures are discontinuities in the rock mass.The fractures are described by thickness,length, distance between the fractures,roughness in planes of weakness, sort ofmaterials found in the fractures, if they areresults of bedding or foliation, and strike anddip if there is a definable pattern. Fractures inthe rock mass are an advantage with respect toadvance rates as long as rock support is notrequired.The above factors are strongly into the picturein the so called Q-method which is a method todefine the rock mass quality with respect tostability and the need for rock support. Variousclasses of rock mass quality which go fromexceptionally good to exceptionally poor willrequire from no support at all, spot bolting,systematic bolting, shotcrete etc. to castconcrete lining.

3. Too Hard Rock is normally a cutter-problem.The cutters are spoiling and/or heavily wornand the penetration rate is reduced. Due tofrequent cutter inspections and -changes theutility time goes down and consequently alsothe Gross Advance Rate.Great efforts are constantly made to increasethe cutter quality. Much is achieved byimproving the steel quality in the rings and byincreasing the size of the cutters and thus beable to use bigger and better bearings.To change the size of cutters is theoretical, butnormally not a practical solution to meet asection of too hard rock in a tunnel.If the <<too hard rock>> problem seems to bepermanent it is a possibility to call for a specialstudy of the rock in order to improve the cutter-result and/or to call for competing suppliers ofcutters.Cutters with tungsten-carbide inserts areexpensive, but may be the solution for a shortperiod. Tungsten-carbide inserted cutters canalso be used together with normal cutters inpositions that are most exposed, for instance asgauge cutters.

4. High Temperatures in the tunnelIn tropical areas the outdoor temperature mayalso be very high, at least during daytime.Cooling of the ventilation air will therefore bea necessity in such areas. Together with thecooling effect from the evaporation of theflushing water it is absolutely possible toachieve livable temperatures.

5. Combustible GasesThe TBM itself and supplementary machineryand all electrical installation must be insulatedto prevent any explosion to come from sparklesor heating. Gas Detection instruments must beinstalled.In dimensioning of the ventilation system theoccurrence of gases and dust must be taken intoconsideration.In countries where the above are frequentoccurrences there are normally very strictregulations with regards to what to do toprevent explosion and also what to do if theaccident should happen.Dust with quartz appears frequently inconnection with hard rock boring. It is notcombustible, but a serious hazard to the healthif breathed for a long period. It is partly aventilation matter to remove the dust from theworking area, and partly.

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Germany, Switzerland and Austria

Tunnelvortriebsmaschinen Tunnel Boring Machines

Empfehlungen zur Auswahl und Bewertung von Tunnelvortriebsmaschinen

Recommendations

for

Selecting and Evaluating Tunnel Boring machines

DAUB

Deutscher Ausschuss für unterirdisches Bauen (DAUB)Österreichische Gesellschaft für Geomechanik (ÖGG) undArbeitsgruppe Tunnelbau der Forschungsgesellschaft fürdas Verkehrs- und Strass enwesenFGU Fachgruppe für Untertagbau Schweizerischer lngenieur-und Architekten-Verein

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1. Purpose of the recommendations......................................................................................................12. Geotechnics .........................................................................................................................................13. Construction methods for mined tunnels.........................................................................................2

3.1. Survey..........................................................................................................................................23.2. Explanation of the Construction Methods..............................................................................3

4. Tunneling machines TM....................................................................................................................54.1. Tunnel Boring Machines (TBM) .............................................................................................5

4.1.1. Tunnel boring machines without shields .......................................................................54.1.2. Tunnel boring machines with shields TBM-S...............................................................5

4.2. Shield Machines SM .................................................................................................................54.2.1. Shield Machines with full-face excavation SM-V........................................................54.2.2. Shield machines with partial axe excavation SM-T .....................................................7

4.3. Adaptable dual purpose shield machines................................................................................94.4. Special forms..............................................................................................................................9

4.4.1. Finger shields.....................................................................................................................94.4.2. Shields with multi-circular cross-sections .....................................................................94.4.3. Articulated shields.............................................................................................................94.4.4. Cowl shield ........................................................................................................................94.4.5. Displacement shield..........................................................................................................94.4.6. Telescopic Shields.............................................................................................................9

4.5. Supporting and lining..............................................................................................................104.5.1. Tunnel boring machines TBM.......................................................................................104.5.2. Tunnel boring machines with shield TBM-S and shield machines SM ..................10

5. Relationship between geotechnics and tunneling machines.......................................................115.1. Ranges of application for tunneling machines.....................................................................115.2. Important selection and evaluation criteria ..........................................................................125.3. Pointers for special geotechnical and constructional conditions.......................................15

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1. Purpose of the recommendations

The developments in mined tunneling arecharacterized by an increased trend towardsfully mechanized tunneling with appropriatetunneling machines (TBM) in solid rock andsoft ground. The creation of special methodssuch as face supporting with fluid or slurry aswell as the successful utilization of cutter discsfor removing rock-like intrusions and bouldershave led to a considerable expansion of thefield of application and to an increase in theeconomy of these tunneling systems.The increasing application of tunnelingmachines and the related continuousimprovement of the various extractiontechniques had led to types of machines, whichhave the capacity to penetrate extremelyheterogeneous subsoil, that is respectively amixture of soft ground and solid rock. Theclear distinction between tunnel boringmachines (TBM) for solid rock and shieldmachines (SM) for soft ground, which resultedfrom their conceptional background and thespecial engineering and extraction technology,has lost its original significance. Pastdevelopments and the progress made inpractice have produced tunneling machines, inwhich the typical features of both techniqueshave been integrated in a single unit. In thisway, the possibility has been created to makeavailable tunneling machines suitable for theentire geotechnical spectrum.The anticipated geotechnical conditions inconjunction with the course of the route andgradient represent the decisive prerequisites forselecting the tunneling method. By comparisonof the cross-section needed for the purpose ofthe tunnel, its length and the geotechnicalconditions with the available technology, themost suitable tunneling machine can bedevised. These recommendations apply tointer-relationships, which exist between thegeotechnical circumstances and process andengineering techniques.When selecting tunneling machines, theenvironmental compatibility of the tunnelingmethods must also be taken into consideration.These recommendations should also be seen asan additional aid, designed to serve theengineer in arriving at a decision. A project-related analysis is, however, essential and

represents the main basis for the approach.These recommendations do not apply, or onlyto a certain extent for micro tunneling.

2. Geotechnics

The knowledge of the geotechnical conditionsis the most important principle for the planningand execution of a tunneling project. Theevaluation of general and special maps leads toinitial recognition about the geological andhydrogeological conditions and providepointers for further investigatory measures. Bymeans of suitable preliminary explorations, thenature and features of the subsoil that must bepenetrated during the construction of a tunnelcan be described. The accuracy of thisdescription depends on the type and extent ofthese pre-investigations as well as theirvalidity. Extremely variable geologicalconditions call for more intensive ofpreliminary surveys.Conditions which restrict thepre-investigations lead to a limited validity of ageotechnical report. This must be taken intoaccount when assessing the projectedgeotechnical conditions. The aim of thegeotechnical survey must be to present thegeological and hydrogeological conditionsrequired for the tunneling project ascomprehensively and lucidly as possible.The subsoil that has to be penetrated is, by andlarge, examined by means of:_ investigatory boreholes and the obtaining ofbore samples and cores_ exploration and sample-taking on the surface_ dynamic penetration tests, pressure probes_ mechanical borehole examinations, e.g.borehole expansion tests, pressiometer_ geophysical investigation methods_ pump and water injection tests_ exploratory tunnelsThrough these investigations and, above all,through the samples that were taken,characteristic values are obtained or derivedthrough further suitable investigations andcorresponding evaluations.The more comprehensively the preliminaryinvestigations are carried out and the morevalid they are the better the basis for selectingthe tunneling method and the tunneling

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machines.The essential geotechnical parameters arelisted in the following:

solid rock- compressive strength (rock strength)- tensile strength, cleavage strength- shearing strength- break and bedding planes- degree of decomposition, degree of

weathering- fault zones- mineralogy/petrography- proportions of abrasive minerals- wearing hardness/hardness- water-bearing and water pressure (under-

ground water)- chemical analysis of the water

soft ground- grain distribution curves- angle of friction- cohesion- deposit thickness- compressive strength- shearing strength- pore volume- plasticity- swelling behavior- permeability- natural and artificial intrusions and faults- water-bearing and water pressure (ground

water)- chemical analysis of the water

special features- primary stress state- rock burst- fault zones- weakening due to leaching processes- heaving/swelling rock- subsidence and subsidence chimneys- karst manifestations- gases- rock temperature- seismic actionMore detailed information relating toinvestigating the subsoil is contained in DIN4020-Geotechnical Invest igat ions forConstruction Purposes. Further pointers arecontained in the “Recommendations forTunneling - Chapter 3: GeotechnicalInvestigations” , published by the DGGT.From the cited geotechnical characteristic

values and an overall appraisal of thegeological and hydrogeological conditions ofthe subsoil, generally speaking, the followingextremely important technical data can beobtained:- ease of break-out of the subsoil- stability of the subsoil- stability of the face- measures for supporting the face- nature and extent of the supporting measures- time lag between breaking-out and securing

the subsoil- deformation behavior of the subsoil- influence of underground and/or groundwater- abrasiveness of the subsoil- stickiness of the excavated soil- separability of the excavated soil (when using

a supporting fluid)- suitability for reutilization of the excavated

soil

Factors, which influence the environment,must also be observed, such as e.g.:- surface settlements- interference with and changes to

the groundwater conditions- suitability of the excavated material for

landfill- contamination of the subsoil and groundwater- health-jeopardizing influencesOn the basis of the listed geotechnicalcharacteristic values and constructional dataincluding the environmentally relevant factors,it is possible the select the construction methodand to divide the tunnel over its route intotunneling classes, which closely define thetunneling method, identify the performances tobe applied per tunneling class and describe thedegree of difficulty. Whereas the selection ofthe construction method is the prerequisite forallocation into tunneling classes (laid down bythe client), the choice of the machine should beleft open as far as possible and left up to theresponsible contractor (choice of theconstruction company).

3 . Construction methods for minedtunnels

3.1. SurveyDifferent construction methods are availablefor executing a tunnel by mining. They can besplit up into the groups-universal headings,

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mechanical headings (tunneling machines) andmicro-tunnel headings. In this connection,those methods for which the extraction resp,the cutting phase is decisive are allocated tosolid rock. In the case of soft ground, on theother hand, the supporting and/or securing ofthe subsoil is accorded priority(Fig.1).In conjunction with the special demandsplaced on a tunnel and taking environmentalfactors into consideration, a general assessmentof the tunneling methods with respect to theirsuitability in individual cases can be carriedout.The remainder of these recommendations dealexclusively with the process technical featuresto be considered when using tunnelingmachines, and essential selection andevaluation criteria for the correspondinggeotechnical fields of application.

3.2. Explanation of the ConstructionMethods

The “shotcreting construction method” is anindependent method, whose possibilities orrather principles of supporting the cavitycombine with various tunneling methods.Under the term “tunneling with systematicallyadvancing support”, we understand tunnelingmethod which embrace the systematic and thusnot simply the partial application of suitablesupporting means, which are applied for theadvance stabilization of the face area. Theseinclude: the forepoling method, methods withpipe screens, screens comprising injectionlances, screens with freezing lances, screenscomprising horizontal HPG columns.Large-area freezing or grouting is methodsdesigned to improve the subsoil, which thenfacilitate the application of a constructionmethod such as shotcreting. The tunnelingclassification then relates to the improvedsubsoil conditions.Whereas the form and size of the cross-sectionin the case of the “universal headings” can beas desired and in fact, can alter within a lengthof tunnel, this flexibility does not exist whentunneling machines are applied.Generally speaking, tunneling machines inaccordance with their function are circular andthus possess a given shape. This restricts theirapplication should the utilization of a circularcross-section not be purposeful or necessaryand therefore, increases the costs. Tunnelingmachines have also been developed which do

not drive circular cross-sections.Tunneling machines are, by and large, gearedto their diameter. This applies, first andforemost, to shield machines. In the case oftunneling machines for solid rock, a certainvariation of the diameter is possible if a shieldbody is not required.Recent developments allow shield machines tobe modified for different diameter ranges in afairly straightforward fashion. In addition,shield machines have been devised which arefitted with two or three overlapping cuttingwheels staggered one behind the other. In thisway, cross-sections which are not circular canbe driven. The installations in question arespecial forms of shield machines for specialpurposes.Apart from these machines being geared to acircular form and diameter, the length of thesections to be driven represents a furtherimportant feature especially for the economicapplication of a tunneling machine.The profile accuracy of the cavity cross-sectionis particularly high when tunnel machines areused. During heading, care should be taken toensure that the predetermined drivingtolerances are adhered to. Unscheduleddeviations from the axis can,in contrast to universal headings, by and largeonly be corrected with considerable difficulty.

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Bautechnische Merkmale

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II-5

4. Tunneling machines TM

Tunneling machines (TM) either head theentire tunnel cross-section with a cutter head orcutting wheel full-face or in part segments bymeans of suitable extraction equipment.During the excavation phase, the machine ismoved forward either continuously or stroke-by-stroke.A difference is drawn between tunnel boringmachines TBM and shield machines SM.Tunnel boring machines remove the rock at theface, with the support generally being installedafterwards, following up at a distance.The machines are held in place during theexcavation phase by means of grippers pressedlaterally against the tunnel walls.Shield machines generally support the subsoilthat is being penetrated and the face by directmeans during the excavation phase. The shieldis advanced during excavation by jackingagainst the completed lining.A systematic compilation of tunneling ma-chines is provided in Fig. 2, which was basedon the classification contained in this section.

4.1. Tunnel Boring Machines (TBM)A distinction is drawn between tunnel boringmachines without shield body and those withone(Fig.3).

4.1.1. Tunnel boring machines withoutshieldsTunnel boring machines are employed in solidrock with medium to high face stability. Theydo not possess a completely closed shieldbody. Economic application can be stronglyinfluenced and restricted through high wearcosts of the cutting tools.Generally speaking, only a circular cross-section can be broken out by these machines.A rotating cutter head, which is equipped withroller bits (discs), possibly with tungstencarbide bits, is pressed against the face andremoves the rock through its notch effect. Inorder to provide the contact pressure at thecutter head, the machine is held radially bymeans of hydraulically moveable grippers.Extraction is gentle on the rock and results inan accurate profile.The machine occupies a large part of the cross-section. Systematic supporting is normallycarried out behind the machine (10 to 15 m andmore behind the face). In less stable and

particularly in friable rock, it must be ensuredthat the placing of support arches, laggingplates and anchors, in certain cases, evenshotcrete, is possible directly behind the cutterhead. It should be possible to carry outpreliminary investigations a n d rockstrengthening from the machine.In the case of bore diameters of > 10 m, so-called expansion machines can also be applied.Starting from a continuous pilot tunnel, theprofile is expanded in one or two workingphases using correspondingly designed cutterheads.During excavation at the face, small pieces ofrock, accompanied by an amount of dust, areproduced. As a consequence, devices forrestricting the dust development and dedustingare necessary for these machines:_ wetting with water at the cutter head_ dust shield behind the cutter head_ dust removal with dedusting on the back-upThe material transfer and supplies for themachine call for what, in some cases, can bevery long back-up facilities.

4.1.2. Tunnel boring machines with shieldsTBM-SIn solid rock with low stability or friable rock,tunnel boring machines are equipped with aclosed shield body. In this case, it is advisableto carry out supporting within the protection ofthe shield tail skin (segments, pipes, etc.),against which the machine supports itself. Thegripper system is then no longer needed.Otherwise, the explanations already providedfor tunnel boring machines also apply here.

4.2. Shield Machines SMA distinction is drawn between Shield Ma-chines with full-face extraction (cutter head)SM-V and shield machines with part extraction(milling boom, excavator)SM-T.Shield machines are employed in loose soilswith or without groundwater, in the case ofwhich generally the subsoil surrounding thecavity and the face have to be supported. Thecharacteristic feature of these machines is thetype of face support (Fig. 3).

4.2.1. Shield Machines with full-faceexcavation SM-V4.2.1.1 SM-V1 Face without supportIf the face is stable, e.g. in clayey soils, so-called open shields can be employed. The

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cutter head equipped with tools removes thesoil; the loosened soil is carried away bymeans of conveyor belts or scraper chains.

4.2.1.2 SM-V2 Face with mechanical supportSupporting of the face is carried out via analmost closed cutter head. The plates arrangedbetween the spokes are elastically supported;they are pressed up against the face. Extractionis executed full-face via the cutter headequipped with tools; the loosened soil passesthrough slits, whose opening width is variable,between the spokes and the supporting plates,into the working chamber.The material is removed via conveyor belts,scraper chains or by hydraulic means.Scraper disc shields possess a high degree ofmechanization. Through the constant full-facecontact of the cutting wheel with the face, hightorque is required.In the case of types of soil, which tend to flow,supporting in the vicinity of the slits isincomplete, which can lead to settlements. It isextremely difficult to remove obstacles.

4.2.1.3 SM-V3 Face with compressed airapplicationIf groundwater is present, it has to be held backin the case of machines belonging to typesSM-V1 and SM-V2 unless it can be lowered.Either the whole tunnel is subjected tocompressed air or the machine is provided witha bulkhead so that only the working chamber isunder pressure. Airlocks are essential in bothcases.Particular attention must be paid to thecompressed air leakage via the shield tail sealand the lining.The support which is realized by theapplication of compressed air acts directly.Through suitable measures, it is also possibleto avoid an accumulation of compressed air,e.g. when sand lenses with water underpressure occur.

4.2.1.4 SM-V4 with fluid supportIn the case of these machines, the face issupported by a fluid that is under pressure.Depending on the permeability of the subsoilthat is present, effective fluids must be used forsupporting, whose density and/or viscosity canbe varied. Bentonite suspension has proved tobe particularly effective.The working chamber is closed to the tunnel

by a bulkhead. The pressure needed forsupporting the face can be regulated with greatprecision either by means of an air cushion orby controlling the speed of the delivery andfeed pumps. Supporting pressure calculationsare required.The soil is removed full-face by means of acutter head equipped with tools. Hydraulicconveyance with subsequent separation isessential.If it is necessary to enter the working chamber(tool change, repair work, removing obstacles),the fluid must be replaced by compressed air.The supporting fluid (bentonite, polymer) thenforms a slightly air-permeable membrane at theface, whose life span is restricted. Thismembrane facilitates the supporting of the facethrough compressed air and should be renewedif need be.When the machine is at a standstill,mechanical supporting of the face is possibleby means of segments, which can be shut, inthe cutting wheel or through plates that can beextended from the rear. These solutions areadvisable on account of the limited duration ofthe membrane.Stones or banks of rock can be reduced to asize convenient for conveyance through discson the cutting wheel and/or stone crushers inthe working chamber.

4.2.1.5 SM-V5 Earth pressure balance faceThe face is supported by earth slurry, which isformed from the material that has beenremoved. The shield's working chamber isclosed to the tunnel by means of a bulkhead.More or less closed cutting wheels equippedwith tools extract the soil. An extraction screwunder pressure carries the soil out of theworking area.The pressure is checked by loadcells, whichare distributed over the front side of thebulkhead. Mixing vanes on the rear of thecutting wheel and the bulkhead are intended toensure that the soil obtains a suitableconsistency.The supporting pressure is controlled throughthe thrust of the rams and the speed of theconveyor screw. The soil material in the screwor additional mechanical installations mustensure a seal in the extraction equipment, asotherwise the supporting pressure in theworking chamber cannot be retained due to theuncontrolled escape of water or soil.

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Complete supporting of the face, especially inthe upper zone, only then succeeds providingthe supporting medium soil- can betransformed into a soft to stiff-plastic mass. Inthis connection, the percentile share of the finegrain smaller than 0.6 mm has a considerableinfluence.In order to extend the range of application ofshield machines with earth pressure balancesupport, suitable agents for conditioning thesoil material can be applied: bentonite,polymer, foam from polymers. In such cases,the environmental compatibility of the materialfor landfill purposes must be taken intoconsideration.

4.2.2. Shield machines with partial axeexcavation SM-T4.2.2.1 SM-T1 Face without supportIf the face is perpendicular or stable with asteep slope, it is possible to use this type ofshield. The machine merely comprises theshield body and the extraction tool (excavator,milling boom or scarifier). The soil is removedvia conveyor belts or scraper conveyors.

4.2.2.2 SM-T2 Face with partial supportThe face can be supported by platforms and/orbreasting plates.In the case of platform shields, the frontsection is divided up by one or a number ofplatforms on which slope form, which supportthe face. The soil is removed manually or bymechanical means.Platform shields possess a low degree ofmechanization. Disadvantageous is the dangerof major settlements resulting from un-controlled face support.

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TBM ohne schild TBMTBMTBM without Shield

TunnelbohrmaschinenTBMTunnel Boring Machines

TBM mit SchildTBM-S TBM-STBM with Shield

Ortsbrust ohne Stützung SM-V1Face without support

Ortsbrusut mitTunnelvortriebs- mechanischer Stützung SM-V2maschinen Face with mechanicalTVM support

TunnellingMachines Schildmaschinen Ortsbrust mit Druckluft-

mit Vollschnittabbau Beaufschlagung SM-V3SM-V Face with compressedShield Machines with air applicationfull-face

Ortsbrust mit Flüssig-Keitsstützung SM-V4Face with fluid support

Ortsbrust mit Erddruck-Schildmaschinen Stützung SM-V5SM Face with earth pressureShielded Machines balance support

Ortsbrust ohne Stützung SM-T1Face without support

Ortsbrust mit Teilstützung SM-T2Schildmaschinen mit Face with purtial supportteiltlächigem AbbauSM-T Ortsbrust mit Druckluft-Shield Machines with Beaufschlagung SM-T3part heading Face with compressed

air application

Ortsbrust mit Flüssigkeits-Stützung SM-T4Face with fluid support

Sonderformen und Kombinationen siehe Textteil / Special forms and combinations are provided in the text

2 Übersicht Tunnelvortriebsmaschinen(TVM).Sonderformen und Kombinationen sind in Text beschrieben Survey of tunnelling machines(TM). Special forms and combinations are described in the article

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In the case of shield machines with breastingplates, the face is supported through breastingplates, which are mounted on hydrauliccylinders. The breasting plates are partiallyretracted for removing the soil manually or bymechanical means.A combination of breasting plates andplatforms is possible. If supporting of the roofarea is sufficient, extensible breasting platescan be used there.

4.2.2.3 SM-T3 Face with compressed airapplicationIf groundwater is present, this must be held incheck in the case of machines of the type SM-T1 and SM-T2. The tunnel is then set undercompressed air or the machines are providedwith a bulkhead. The material is removedhydraulically or dry via a material lock.

4.2.2.4 SM-T4 Face with fluid supportIn the case of this shield type, the workingchamber is also closed by a bulkhead. It isfilled with a fluid, whose pressure is regulatedvia the speed of the delivery and feed pumps.The soil is removed via a cutter, which, insimilar fashion to suction dredgers, also takesaway the fluid-soil mixture.

4.3. Adaptable dual purpose shieldmachines

A large number of tunnels pass throughstrongly varying subsoil conditions, which canrange from rock to loosely bedded soil. As aresult, tunneling methods have to be geared tothe geotechnical prerequisites and shieldmachines, which are correspondinglyadaptable, employed.a) Shield machines, in the case of which theextraction method can be changed withoutmodification:_ earth pressure balance shield SM-V5 _

compressed air shield SM-V3_ fluid shield SM-V4 _ compressed air shield

SM-V3b) Shield machines, in the case of which theextraction method can be changed throughmodification. Findings are available with thefollowing combinations:_ fluid shield SM-V4 _ shield without support

SM-V1_ fluid shield SM-V4 _ earth pressure balance

shield SM-V5_ earth pressure balance shield SM-V5 _ shield

without support SM-V1_ fluid shield SM-V4_ TBM-S

4.4. Special forms4.4.1. Finger shieldsThe shield body is split up into fingers, whichcan be extended individually. The soil isremoved via roadheaders, cutting wheels orexcavators. An advantage of finger shields isthat they deviate from the circular form ande.g. can also excavate horse-shoe profiles. Inthe latter case, the base is usually open. Theforepoling is also used.

4.4.2. Shields with multi-circular cross-sectionsThese shield types represent the latest state ofdevelopment for fully mechanized headings. Inthe case of these machines, the staggeredcutting wheels are designed to overlap.

4.4.3. Articulated shieldsPractically all-existing shields can be providedwith an articulating joint. If the ratio of theshield body length to the shield diameterexceeds the value l, generally a joint isincorporated in order to improve the steability.The arrangement can also be necessary ifextremely tight curve radii are to be driven.

4.4.4. Cowl shieldThe shield cutting edge is tapered toapproximate the natural angle of slope of thesoil. When tunneling under compressed air,this means that safety against blowout isenhanced.

4.4.5. Displacement shieldOnly suitable for soft-plastic soils. Themachine has no extraction tool. It is pressedinto the soil, which results in this beingpartially displaced and partially removedthrough an aperture in the bulkhead.

4.4.6. Telescopic ShieldsIn order to arrive at higher rates of advance,telescopic shields have been designed.Essentially, the objective is to install the liningduring the removal of the soil.

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4.5. Supporting and liningAs far as the process techniques referred to inthese recommendations are concerned, thetunneling machine together with the supportand/or lining represent a single unit in terms ofprocess technology.

4.5.1. Tunnel boring machines TBMDue to the excavation procedure which isgentle on the rock and the advantageouscircular form, the extent of the necessarysupporting measures is usually less than forexample for drill + blast. In less stable rock,the exposed areas have to be supported quicklyin order to restrict any disaggregation of therock and thus retain the rock quality as far aspossible.Should breaks occur in the vicinity of thecutter head, the extent of the necessarysupporting measures can increase considerably.

4.5.1.1 Rock boltsRock bolts are generally arranged radially inthe cross-sectional profile of the tunnel, a rockmatrix-oriented set-up enhance the effect of theshear dowels. Installed locally, they prevent theflaking or detaching of rock plates, arrangedsystematically, they prevent loosening of theexposed tunnel sidewall. Rock bolts areespecially suitable for subsequently increasingthe lining strength, as they can still be installedat a later stage.The anchors are installed in the vicinity of theworking platform behind the machine or inspecial cases, directly behind the cutter head.

4.5.1.2 ShotcreteShotcrete serves to seal the exposed rocksurface either partially or completely (thick-ness 3 to 5 cm) or provide it with a supportinglayer (thickness 10 to 25 cm, in exceptionalcases, even more). In order to enhance theloadbearing capacity of the shotcrete lining, itis provided with a single-layer (on The rockside) or two-layers (rock and exposed side) ofmesh reinforcement. Alternatively, steel fibbershotcrete can be applied. The shotcrete isgenerally installed in the vicinity of theworking platform behind the machine.4.5.1.3 Support archesSupport arches serve to effectively support therock directly after the excavation and to protectthe working area. As a consequence, they are,first and foremost, applied in friable and

unstable, squeezing rock. Rolled steel sectionsor lattice girders are used as support arches.Support arches are normally installed directlybehind the cutter head in sections in the roofzone or as a closed ring.

4.5.2. Tunnel boring machines with shieldTBM-S and shield machines SMIn the case of tunnel boring machines withshield or shield machines, the support isinstalled within the protection of the shield tail.This usually consists of prefabricatedsegments.Apart from supporting the surrounding subsoil,it serves in the case of most machines of thistype as the abutment for the thrust rams.The load transfer between the lining and thesubsoil is created by grouting the annular voidat the shield tail as continuously as possible.This does not apply to lining systems, whichare directly pressed against the subsoil.In general, it must be ascertained whether alining comprising an inner shell made ofreinforced or un-reinforced concrete is needed.Segments and pipes are normally utilised assingle skin linings.

4.5.2.1 Concrete and reinforced concretesegmentsThe customary precast elements are concreteor reinforced concrete segments. Alone thestresses caused by transport and installationmakes it necessary for the segments to bereinforced. Segments with steel fibberreinforcement have also been designed in orderto strengthen the edges and corners, whichcannot be reinforced by rods, through steelfibbers.

4.5.2.2 Cast steel and steel segmentsThrough the development of castingtechnology, segments today can be suppliedmade of cast steel, e.g. with the materialdesignation GGG 50, with low overallthickness, sufficient dimensional accuracy andsufficient elasticity.In exceptional cases, as e.g. extremely narrowcurves and in the vicinity of apertures in thelining, welded steel segments can represent atechnical solution for overcoming load con-contortions on the lining.

4.5.2.3 Liner plates

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Pre-formed steel plates in the form of linerplates can represent an economic solution as afull surface provisional support in extremelyfriable rock.

4.5.2.4 Extruded concreteExtruded concrete is a tunnel lining, which isinstalled, in a continuous workingprocess as an unreinforced or steel-fibrereinforced concrete support behind thetunneling machine between the shield tail anda mobile inner form. Thus, the extrudedconcrete in its fresh state already supports thesurrounding rock, also in groundwater. Anelastically supported stop-end formwork,which is pushed forwards concrete pressure,assures a constant support pressure in theliquid concrete.

4.5.2.5 Timber laggingIn non-water bearing soil, the primary supportcan comprise a wooden or reinforced concreteslatted construction, which is installed betweensteel profiles (ribs and lagging), which isassembled protected by the shield tail. Whenthe shield tail releases the steel ribs, they and,in turn, the lagging, are pressed against the soilusing hydraulic jacks. The tunneling machinecan be advanced by thrusting against this pre-stressed construction.

4.5.2.6 PipesPipe-jacking represents a special method, inthe case of which reinforced concrete or steelpipes are thrust forward from a jacking stationto serve as a support and/or final lining.For certain construction projects, rectangularcross-sections are also employed with thejacking method.

4.5.2.7 Reinforced ConcreteReinforced concrete is only used n conjunctionwith blade shields. In the same way asshotcrete, reinforced shotcrete can be appliedin conjunction with tunneling machines forsupporting purposes when they do not transferthe thrusting forces onto the lining. Thereinforced concrete is produced in 2.50 to 4.50m wide sections protected by so-called trailingblades, which are supported on the lastconcreted section by conventional means withmobile formwork.

5 . Relationship between geotechnics

and tunneling machines

5.1. Ranges of application for tunnelingmachines

The individual tunneling machines are suitablefor certain geotechnical and hydro-geographical ranges of application in con-junction with their process-related andtechnical features.The specific types of machines are related totheir main ranges of application in Fig.4 withgeo-technical terms and parameters as thebasis. In addition, it is shown there just how faran extension of the range of application ispossible should this present itself as a result ofsimplified methods, in order to increase theeconomy or with regard to the heterogeneity ofthe subsoil that is present.As one of the most essential influencingfactors for the application is the lack orpresence of groundwater, the fields ofapplication are divided into subsoil with orwithout groundwater.Extremely varied extraction tools can be usedfor removing the subsoil that is present. Theyare listed in accordance with their suitabilityfor the geotechnical ranges of application andthe machine types.The forms of supporting and lining suit ablefor the individual machines are presentedunder 4.5. As a result, they have not been listedseparately in a table.

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3. Systeme der Tunnelvortriebsmaschinen

Tunneling machine systems

5.2. Important selection and evaluationcriteria

TBMThe main range of application is in stable tofriable rock, in the case of which undergroundand fissure water inbursts can be mastered. Theuni-axial compressive strength should amountroughly to between 300 and 50 [MN/m2].Higher strengths, toughness of the rock and ahigh proportion of abrasion resistant mineralsrepresent economic limits for -

application (abrasiveness according to Cerchar,Schimanek, et al). A restriction of the gripperforce of the TBM can also place its applicationin question.To assess the rock, the cleavage strength _z

≈25 to 5 [MN/m2] and the RQD value arerequired. Given a degree of decomposition ofthe rock with RQD of 100 to 50 [%] and afissure spacing of > 0.6 m the application of aTBM appears assured.Should the decomposition be higher, thestability has to be checked.

TBM-SThe main field of application is in friable tounstable rock, also with inbursts ofunderground and fissure water. The bondingstrength is greatly reduced given possibly thesame rock strength in stable rock. Thiscorresponds to a fissure gap of ≈ 0.6 to 0.06[m] and a RQD value between approx. 50 and10 [%]. Generally, however, an application ofthe TBM-S is possible given lower rockcompressive strength _D between approx. 50and 5[MN/m2] and correspondingly lesscleavage strength of _z between approx. 5 and0.5 [MN/m2].

SM-V1This type of machine is mainly used in over-consolidated and thus dry, stable clay soils. Inorder to make sure that no harmful surfacesettlements occur even given thin overburdens,the compressive strengths _D of the materialshould not be less than approx. 1.0 [MN/m2].The cohesion cu accordingly registers valuesabove approx. 30 [kN/m2].Only in rock which is relatively immune tooverbreak can underground and fissure wateringress be coped with.

SM-V2On account of the full-face supporting cutterhead, easily removed, largely dry types of soilcan be mastered, first and foremost non-stablecohesive soils or interstratifications comprisingcohesive and non-cohesive soils. Majorintercalation such as boulders is extremelydifficult to cope with.The cohesion cu of these soils amounts tobetween 30 and 5 [kN/m2]. The grain size isrestricted upwards due to the slit width in thecutter head. In order to ensure that surfacesettlements are kept to a minimum, the slit

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width and contact pressure have to beoptimized.

SM-V3This machine under compressed air working ismainly used when types SM-V1 and SM-V2have to operate in groundwater. Its mainapplication must be regarded as in soils withinterstratification. The air permeability of therock and the air consumption and the relatedblow -out danger are the governing criteria forthe application of this type of machine.

SM-V4Its main range of application is tunneling innon-cohesive types of soil with or withoutgroundwater.During the excavation process, a fluid underpressure e.g. bentonite suspension supports theface. Layers of gravel and sand are the typicalsubsoil. Coarse gravel can in certain casesprevent membrane formation. In the event ofhigh permeability, the supporting fluid must beadapted to suit. Major stratification, whichcannot be pumped, is reduced in advancecrushers. The proportions of ultra-fine grain <0.02 mm should amount to ≈ 10%. Higherquantities of ultra-fine material can lead todifficulties during separation.

SM-V5Types of machines with earth pressure balancesupporting are especially suitable for withcohesive fractions. In this case, the proportionof ultra-fine grains < 0.06 mm should amountto at least 30 %. In order to produce the desiredearth slurry, groundwater has to be present orwater must be added. The necessaryconsistency of the spoil can be improvedthrough the addition of suitable conditioningagents such as bentonite or polymer. In thisway too, the danger of sticking is considerablyreduced.

SM-T1This type of machine can be used providing theface is thoroughly stable. Refer also to SM-T1.

SM-T2This type of machine can be used when thesupport due to the material lying on theplatforms at a natural sloping angle suffices fora conditional control of deformations duringtunnel advance. Breastplates can be used for

supporting purposes in the roof and platformzone. Slightly to non-cohesive clay-sand soilswith a corresponding angle of friction are themain range of application.

SM-T3The application of this type of machine isgiven when types SM-T1 and SM-T2 are to beused in groundwater. Either the entire workingarea, including the excavated tunnel or solelythe working chamber is subjected tocompressed air.

SM-T4When clay-sand mixtures are to be removedunder water, this type of machine is used. Therequirements concerning the groundcorrespond to type SM-T4. Obstacles can becleared using the cutting boom. Supportingplates are arranged in the roof zone.

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4

σ σ

≥ ≥≥

Baugrund

Geo-

subsoil

standfest

nachbr

chig

bindig

bindig

Wechsellagerung

nicht bindig

technische

bis nachbr

chig

bis gebr

ch

standfest

nicht standfest

kennwerte

competent to

caving in to

cohesive

cohesive

mixed

non-cohesive

Geotechinical Parameters

caving in

unstable

stable

not stable

conditions

Gesteinsfestigkeit

D[MN/ ‡u]

Rock Compressive strength

Zugfestigkeit

z[MNl ‡u]

Tensile strength

RQD-Wert

RQD[%]

RQD value

Kluftabstand

[m]

Fissure spacing

Koh

sion

Cu[kNl ‡

u]Cohesion

Kornverteilung

<0,02[%]

30

30

10

Grain distribution

<0,06[5]

30

30

TBM

0.W.

TBM

m.W.

TBM-S mit Schild

o.W.

TBM-S with shield

m.W.

SM-V1 ohne St

zung

o.W.

SM-V1 without support m.W.

SM-V2 mechan.St

zungo.W.

SM-V2 mech.support

m.W.

SM-V3 mit Druckluft

o.W.

SM-V3 with compressed air

m.W.

SM-V4 Fl

ssigkeitsst

tzung

o.W.

SM-V4 fluid support

m.W.

SM-V5 Erddruck-St

tzung

o.W.

SM-v5 earth pressure

balance support

m.W.

SM-T1 ohne St

tzung

o.W.

SM-T1 without supportm.W.

SM-T2 Teilst

zung

o.W.

SM-T2 partial su

m.W.

SM-T3 mit Druckluft

o.W.

SM-T3 with compressed air

m.W.

SM-T4 Fl

ssigkeitsst

tzung

o.W.

SM-T4 fluid support

m.W.

Abbauwerkzeug

Vrollend

rollend

sch

lend

sch

lend

lsend/sch

lend

lsend

Extracion tool

(Diskenmei§el)

(Diskenmei§el)

(Flachmei§el)

(Flachmei§el)(Stichel/Flachmei§el)(Stichel)

rolling

rolling

stripping

stripping

loosening/strippingloosening

(cutter disc)

(disc bit)

(flat bit)

(chisel)

(cutter/flat bit)

(pick)

Tritzend

ritzend

ritzend

sch

lend

sch

lend

lsend

(Spitzmei§el)

(Spitzmei§el)

(Spitzmei§el)

(Flachmei§el)

(Flachmei§el)

(Stichel)

notching

notching

notching

stripping

stripping

loosening

(pick)

(point bit)

(point bit)

(flat bit)

(flat bit)

(pick)

o.W.=ohne Grund-bzw.Schichtwasser/

without groundwater or underground water

Haupteinsatzbereich

/Main field of appl

m.W.=mit Grund-bzw.Schichtwasser/

with groundwater or underground water

Einsatz m

glich/

application possible

4 Einsatzbereich der Tunnelvortriebsmaschinen

Ranges of application for tunnelling machines

100 bis 50

>2,0 bis 0,6

50 bis 10

0,6 bis 0,06

30

30 bis 5

30 bis 5

1,0

25 bis 5

Fels/Festgestein/

Hard rock/soil

Boden/Lockergestein/

Soft rock/soil

0,1

50 bis 5

5 bis 0,5

300 bis 50

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5.3. Pointers for special geotechnical andconstructional conditions

Due to special marginal conditions, theapplication of a certain method and/or atunneling machine can be considerablyrestricted. By use of suitable measures,however, an application can be made possible,above all, providing these special conditionsonly occur locally or over a limited zone. Thedecisive factor is then the economic feasibility.Through lowering the groundwater, asimplified technique for the tunnelingmachines can be applied, which e.g. facilitatesthe removal of obstacles, should these beexpected at very frequent intervals.In the case of strongly fluctuating geotechnicalconditions, the possibility of being in aposition to adapt the operating mode of thetunneling machine brings advantages. This is,above all, purposeful when lengthy inter-connected sections are concerned (see 4.3).When selecting the suitable tunneling ma-chines, a critical evaluation of eventualadditional equipment is advisable, which maybe required to cope with any deviations fromthe projected geotechnical conditions within acertain range.By means of grouting, freezing, vibratorcompaction or soil replacement, the subsoilcan be improved. This is suitable for the entiretunnel cross-section but most importantly forthe area above the tunnel when only thinoverburden is present.Using compressed air when a thin overburdenis present, e.g. below a watercourse, ballast ora waterproofing and ballasting layer should beinstalled.When fluid support is used, additionalmeasures are required in order to avoiduncontrollable suspension losses given highpermeability of the soil and thin overburden.Should there be a high frequency of coarsegravels and boulders in the sand, the utilizationof a rock crusher enhances the operationalsafety in the case of fluid supported shieldmachines in addition to equipping the cutterhead with cutter discs.A tunneling machine is only in the position tohead a circular cross-section, which has aconstant diameter. However, it is technicallypossible to expand the driven circular cross-section over short stretches subsequently insuch a way that other, above all larger cross-sectional forms are created, e.g. for a

subterranean station, employing soilimprovements should these be called for.The greater the proportion of ultra finematerial in the subsoil, the more attention hasto be paid to spoil separation in the case offluid supported shield machines.The requirements on the water content and/orthe degree of purity of the separated soilmaterial then govern the limits of the economyof the method.The operational safety of a method is, amongother things, dependent on a tunnel’s over-burden. This should generally correspond atleast to the diameter of the tunnel excavated, ifadditional measures are to be avoided. Thismust be accorded special attention in the caseof large diameters.The unrestricted application of certain types ofmachine is not always assured as the diameterincreases and is only possible in conjunctionwith suitable measures. In the case of tunnelboring machines with large diameters,machines with shield body and systematicplacing of segments have proved themselves.As far as earth pressure balance shieldmachines are concerned, extremely hightorques at the cutter head are necessary, whichpossibly cannot be attained in the case of verylarge diameters.As far as earth pressure balance shieldmachines are concerned, cutter discs can beemployed for reducing coarse gravel andboulders. The dimensions of the screwconveyor must be designed in such a fashionthe coarse lumps which are present afterextraction can be removed. A screw without ashaft is suitable for conveying coarse lumps.Certain clays or rocks containing clay cancause the cutter head to stick and to formbridges over apertures for removing material.This phenomenon can be counteracted throughthe proper shape, flushing installations oradditives, which reduce the stickiness.Ingresses of gas require flameproof protectionfor the tunneling machines or a change ofoperational mode.

Page 62: Recommendations ITA TBM

Italy

ITA WORKING GROUP No. 14(ITA WG14)

“MÉCANISATION DE L’EXCAVATION”“MECHANIZATION OF EXCAVATION”

Tuteur/Tutor Animateur Vice-AnimateurS.KUWAHARA N.MITSUTA M.DIETZ

PRÉPARATION DU RAPPORT “RECOMMANDATIONSPOUR LE CHOIX DES MACHINES FOREUSES”

PREPARATION OF THE REPORT “GUIDELINES FOR THESELECTION OF TBM’S”

(Contribution from the Italian Tunneling Association“Mechanized Tunneling”working group - GL14, to the ITA

WG14)

World Tunnel Congress‘98Tunnel and Metropolis

24th ITA Annual Meeting25 - 30 April 1998Sao Paulo - Brazil

Page 63: Recommendations ITA TBM

III-ii

CONTENTS

1. Aim and Scope (deleted)........................................................................................................................12. Classification and Outline of Tunnel Excavation Machines .............................................................1

2.1. Classification of tunnel excavation machines.............................................................................12.2. Rock tunneling machines ..............................................................................................................3

2.2.1. Unshielded TBMs..................................................................................................................32.2.2. Special Unshielded TBMs....................................................................................................32.2.3. Single Shielded TBMs: SS-TBMs ......................................................................................32.2.4. Double Shielded TBMs: DS-TBMs....................................................................................4

2.3. Soft Ground Tunneling Machines ................................................................................................42.3.1. Open Shields ..........................................................................................................................42.3.2. Mechanically Supported Closed Shields............................................................................42.3.3. Mechanical Supported Open Shields..................................................................................52.3.4. Compressed Air Closed Shields ..........................................................................................52.3.5. Compressed Air Open Shields.............................................................................................52.3.6. Slurry shields..........................................................................................................................52.3.7. Open slurry shields................................................................................................................62.3.8. Earth Pressure Balance Shields – EPBS ............................................................................62.3.9. Combined Shields: Mixshield, Polyshield.........................................................................7

3. Conditions for Tunnel Construction and Selection of TBM Tunneling Method ...........................73.1. Investigations ..................................................................................................................................7

3.1.1. Introduction ............................................................................................................................73.1.2. Parameter selection..............................................................................................................123.1.3. Monitoring during construction.........................................................................................243.1.4. TBM tunneling monitoring system...................................................................................24

4. REFERENCES......................................................................................................................................28

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1. Aim and Scope (deleted)

2. Classification and Outline ofTunnel Excavation Machines

2.1. Classification of tunnel excavationmachines

All over the world there are differentclassification schemes for tunnel excavationmachines (TMs), based on differentclassification purposes.

The proposed classificat ion schemerepresented in fig. l is based on the possibilityof dividing TMs on the basis of_

_ ground support system_ excavation (method and tools)_ reaction force tool

Following the two machine categories intowhich all TMs may be grouped, the nextparagraphs broadly illustrate all types of TMs.

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2

2.1

- G

ener

al c

lass

fca

ton

sch

eme

for

tun

nel

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mac

hn

e -

Gen

eral

cla

ssif

icat

ion

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for

tun

nel

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Ex

cav

atio

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Ex

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atio

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cav

atio

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ion

Ex

cav

atio

n

Ex

cav

atio

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cav

atio

n

Ex

cav

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cav

atio

n

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atio

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cav

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cav

atio

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atio

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cav

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Ex

cav

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cav

atio

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atio

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Ex

cav

atio

nE

arth

P

ress

ure

B

alan

ce

Sh

ield

-EP

BS

Spe

cial

EP

BS

EarthPressureBalanceShield-EPBS

Special

Ear

th P

ress

ure

Bal

ance

S

hie

ld-E

PB

S S

peci

al E

PB

S

Ear

th

Pre

ssu

re

Bal

ance

S

hie

ld-E

PB

S S

peci

al E

PB

S

Ex

cav

atio

n

Ex

cav

atio

nE

xca

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ion

Excavation

Ex

cav

atio

n

Ex

cav

atio

n

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atio

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Ex

cav

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n

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Excavation

Ex

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Excavation

Ex

cav

atio

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Excavation

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2.2. Rock tunneling machines

2.2.1. Unshielded TBMs

Function principle – A cutterhead, rotating onan axis which coincides with the axis of thetunnel being excavated, is pressed against theexcavation face; the cutters (normally disccutters) penetrate into the rock, pulverizing itlocally and creating intense tensile and shearstresses. As the resistance under each disccutter is overcome, cracks are created whichintersect creating chips. Special buckets in thecutterhead allow the debris to be collected andremoved to the primary mucking system. Theworking cycle is discontinuous and includes:1) excavation for a length equivalent to theeffective stroke; 2) regripping; 3) new -excavation.Main components of the machine - The TBMbasically consists of:_the traveling element which basically consists

of the rotating cutting head and the primarymucking system_

_a stationary element which counters the thrustjacks of the cutterhead using one or morepairs of grippers which anchor the TBMagainst the tunnel walls_

_a rear portion containing the driving gear andback-up elements;

Depending on the type of stationary element itis possible to divide unshielded TBMs into:main beam types or kelly types.Main field of application - Rock masses whosecharacteristic range from optimal to moderatewith medium to high self-supporting time.

2.2.2. Special Unshielded TBMs

2.2.2.1 Reaming Boring Machines - RBMsFunction principle - The Boring Machine is aTM which allows a tunnel made using a TBM(pilot tunnel) to be widened (reaming).The function principle on which it is based isidentical to that for the unshielded TBM; theworking stages are also the same as for theunshielded TBM.Main components of the machine - The RBM

basically consists of:_the traveling element which basically consists

of the reaming head, on which the cuttingtools are fitted_and the primary muckingsystem_

_a stationary element located inside the pilottunnel opposite the reaming head, whichcounters the thrust jacks on the cutting headusing two pairs of grippers;

_a rear portion containing the engines_thedriving gear and back-up elements.

A special type of RBM is the Down ReamingBoring Machine_this machine is used for shaftexcavation and enables the top-to-bottomreaming of a pilot tunnel dug using a RaiseBorer_see below_.Main field of application - Rock masses whosecharacteristics range from optimal to moderatewith medium to high self-supporting time.

2.2.2.2 Raise BorerFunction principle - The Raise Borer is amachine used for shaft excavation whichenables the top-to-bottom reaming of a smalldiameter pilot tunnel created using a drillingrig.A cutterhead, rotating on an axis, whichcoincides, with the axis of the tunnel beingexcavated, is pulled against the excavation faceby a drilling rod guided through the pilottunnel. The cutters provoke crack formationusing the same mechanism illustrated for theunshielded TBMs. Debris falls to the bottom ofthe shaft where it is collected and removed.Main components of the machine - The RaiseBorer basically consists of 3 parts:_ the cutterhead (discs or pin discs);_ the drilling rod which provides torque and

pull to the cutterhead;_ a body, housed outside the shaft, which gives

the drilling rod the necessary torque and pullfor excavation.

Main field of an application - Rock masseswith optimal to poor characteristics.

2.2.3. Single Shielded TBMs: SS-TBMsFunction principle -See the section forunshielded TBMs. Inthis case the workingcycle is also -

Page 67: Recommendations ITA TBM

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discontinuous and includes:l) excavation for a length equivalent to theeffective stroke; 2) regripping (using thelongitudinal thrust jacks braced against theprecast segments of the tunnel lining) andsimultaneous laying of tunnel lining usingprecast segments; 3) new excavation.Main components of the machine_the cutterhead (discs), which can be

connected rigidly to the shield or articulated;_ the protective shield which is cylindrical or

slightly truncated cone-shaped and containsthe main components of the machine; theshield may be monolithic (the machine isguided by the thrust system and/-or cutterhead) or articulated (the machine isguided by the thrust

system and/or shield articulation);_ the thrust system which consists of a series

of longitudinal/hydraulic jacks placed insidethe shield which are braced against thetunnel lining.

Main field of application - Rock masses whosecharacteristics vary from moderate to poor.

2.2.4. Double Shielded TBMs: DS-

TBMs

Function principle -Similar to unshieldedTBMs, but offers thepossibility of a -continuous work cycle

owing to the double thrust system, making itmore versatile since it can move forward evenwithout laying the tunnel lining of precast -segments.Main components of the machine:_ the cutterhead (discs);_ the protective shield which is cylindrical or

slightly truncated cone-shaped and -articulated, and contains the main machinecomponent;

_ the double thrust system which consists of: 1) a series of longitudinal jacks; 2) a series of grippers, positioned inside the

front part of the shield which use thetunnel walls to brace against the thrustjacks.

Main field of application - Rock masses whosecharacteristics range from excellent to poor.

2.3. Soft Ground Tunneling Machines

2.3.1. Open

ShieldsFunction principle -The open shield is aTM in which face

excavation is -accomplished using a partial sectioncutterhead.At the base of the excavating head are handshields and partly mechanized shields in whichexcavation is accomplished using a roadheaderor using a bucket attached to the shield, andusing an automatic unloading and muckingsystem.

Main components of the machine_ the face excavation system;_ the protective shield whose shape can be

altered to suit the type of section to beexcavated (non-obligatory circular section);

_ the thrust system consisting of longitudinaljacks.

Main field of application - Rock masses whosecharacteristics vary from poor to very bad, -cohesive or self-supporting ground in general.It can also be used in ground, which lacks self-supporting capacity using appropriatepreconsolidation or presupport of the -excavation face.

2.3.2. Mechanically Supported Closed

Shields

Function principle -This mechanicallysupported, closedshield is a TBM inwhich the cutterheadplays the dual role of

acting as the cutterhead and supporting theface using mobile plates, integral to thecutterhead, thrust against the face by specialhydraulic jacks. The debris is extractedthrough adjustable openings or buckets andconveyed to the primary mucking system.Main components of the machine_ the cutterhead (blades and teeth);_ the protective cylindrical shield containing

all the main components of the machine;_ longitudinal thrust jacks.Main field of application - Soft rocks, cohesiveor partially cohesive ground, self-supportingground in general. Absence of groundwater.

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2.3.3. Mechanical Supported Open

Shields

Function principle -Similar to that -described for open -Shields; face stability isachieved using metal

plates which thrust alternatively against theface.Main components of the machine - Similar tothose described for open shields; the metal facesupport plates are located in the upper part ofthe section and are integral to the shield.Main field of an application - Soft rocks,cohesive or partially cohesive ground, self-supporting ground in general. Absence ofgroundwater.

2.3.4. Compressed Air Closed Shields

Function principal - Incompressed air closedshields the rotating -cutterhead acts as themeans of excavation

whereas face support is ensured by compressedair at a sufficient level to balance the -hydrostatic pressure of the ground. Debris isextracted from the pressurized excavationchamber using a ball valve-type rotary hopperand then conveyed to the primary muckingsystem.

Main components of the machine_ the cutterhead (blades and teeth);

_ the protective cylindrical shield containingall the main components of the machine; thefront part is closed by a bulk head, whichguarantees the separation between theexcavation chamber (pressurized), housingthe cutterhead, and the zone containing themachine components (unpressurized);

_ longitudinal thrust jacks.Main field of application - Ground lackingself-supporting capacity and with medium-lowpermeability (k ≤ 10 –4m/s). Presence of -groundwater. Higher permeability can belocally reduced by injecting bentonite slurryonto the excavation face. The operating limit ofthe machine is the maximum pressureapplicable based on regulations for the use ofcompressed air in force in different countries.

2.3.5. Compressed Air Open Shields

Function principle - Asin the case of openshields, face -excavation is achievedusing a roadheader;face support is -

provided by compressed air in sufficientquantities to balance the hydrostatic pressureof the ground.Main components of the machine_face excavation system ( roadheader,

excavator);_ protective shield shaped to fit the type of

section to be excavated; the front part, whichhouses the roadheader, is closed by abulkhead separating the shield and -excavation chamber (pressurized);

_ longitudinal thrust jacks.Main field of application - The same as forcompressed air closed shields.

2.3.6. Slurry shields

2.3.6.1.Slurry shields-SS

Function principle - The cutterhead acts as themeans of -excavation whereasface support is -provided by slurry

counterpressure,namely a suspension of bentonite or a clay andwater mix (slurry).This suspension is pumped into the excavationchamber where it reaches the face andpenetrates into the ground forming the filtercake, or the impermeable bulkhead (fineground) or impregnated zone (coarse ground)which guarantees the transfer of -couneterpressure to the excavation face.Excavated debris by the tools on the rotatingcutterhead consists partly of natural soil andpartly of the bentonite or clay and watermixture (slurry). This mixture is pumped(hydraulic mucking) from the excavationchamber to a separation plant (which enablesthe bentonite/clay slurry to be recycled)normally located on the surface.Main components of the machine_ cutterhead (discs, blades or teeth);_ protective shield containing all the main

components of the machine; the front part is

Page 69: Recommendations ITA TBM

III-6

sealed by a bulkhead which guarantees theseparation between the shield and the

excavation chamber (pressurized) containingthe cutterhead;

_ longitudinal thrust jacks;_ mud and debris separation system (normally

located on the surface).Main field of application - Ground with limitedself-supporting capacity. In granulometric -terms, slurry shields are mainly suitable forexcavation in sand and gravels with silts. Theinstallation of a crusher in the excavationchamber allows any lumps, which would notpass through the hydraulic mucking system tobe crushed. The use of disc cutters enables themachine to excavate in rock. Polymers can beused to excavate ground containing much siltand clay. Presence of groundwater.

2.3.6.2 Hydroshields HS

Function principle -Identical to that -described for -uncompensated slurryshields; the only -

difference is the way of transferring thecounterpressure to the face.In the closed slurry shield in which thecounterpressure is compensated inside theexcavation chamber, in addition to the rotatinghead, there is always a metal buffer whichcreates a chamber partially filled with airconnected to a compressor which can adjustthe counterpressure at the face independent ofthe hydraulic circuit (supply of bentonite slurryand mucking of slurry and natural ground)

Main components of the machine - Similar tothose described for closed slurry shields withuncompensated counterpressure.

2.3.7. Open slurry shields

Function principle -It is identical to thatdescribed for -compressed air openshields. In this case face

support is provided by slurry counterpressure.Depending on the function of the cutterheadused, the following types can be identified:

Thixshield: excavation using a roadheaderHydrojetshield: excavation using high-pressurewater jetsMain components of the machine – Similar tothose described for compressed air openshields.Main field of application - Similar to thatdescribed for the closed slurry shield.

2.3.8. Earth Pressure Balance Shields

– EPBS

2.3.8.1 Earth Pressure Balance Shields -EPBS.

Function principle - Thecutterhead serves as themeans of excavationwhereas face support isprovided by the -

excavated earth which is kept under pressureinside the excavation chamber by the thrustjacks on the shield (which transfer the pressureto the separation bulkhead between the shieldand the excavation chamber, and hence to theexcavated earth).Excavation debris is removed from theexcavation chamber by a screw conveyorwhich allows the gradual reduction of pressure.Main components of the machine_ cutterhead: rotates with cutting spokes;_ protective shield similar to that used for

closed slurry shields;_ thrust system: longitudinal jacks which brace

against the lining of precast segments.Main field of application - Ground with limitedor no self-supporting capacity. In -granulometric terms, earth pressure balanceshields are mainly used for excavating in siltsor clays with sand. The use of additives, suchas high-density mud or foams, enablesexcavations in sandy-gravely soil.

2.3.8.2 .Special EPBSDK shield - Differs from the earth pressurebalance shield because of the geometry of thecutterhead whose central cutter projects furtherthan the cutters on the spokes, thus creating aconcave cavity.Double shield (DOT shield) - These are twopartially interpenetrated earth pressure balanceshields which operate simultaneously on thesame plane, creating a “binocular” tunnel.Flexible Section Shield Tunneling Method -

Page 70: Recommendations ITA TBM

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Earth pressure balance shield in which theexcavation system is based on the presence ofseveral rotating cutterheads which enable theconstruction of non-cylindrical sections.Elliptical Excavation Face Shield Method -Earth pressure balance shield in which thecombined action of a circular cutterhead andadditional cutters enables an elliptical sectionto be excavated.

Triple Circular Face Shield Tunnel - Thisconsists of three shields, operating using earthor slurry pressure balance, which allow largeexcavation sections to be constructed, such asthose required to house an undergroundrailway station.Vertical Horizontal Continuous Tunnel - Thisis a slurry pressure balance TM consisting of amain shield, for shaft excavation, whichcontains a spherical joint housing a secondaryshield.When the main shield has reached theappropriate depth, the spherical joint is rotated90_ and the secondary shield starts tunnelexcavation.Horizontal Sharp Edge Curving Tunnel -Similar to the Vertical-Horizontal ContinuousTunnel, it enables the construction of twotunnels intersecting at right angles.Double Tube Shield Technology - This is a TMfitted with two concentric shields. The mainshield excavates the tunnel with the largesection; the secondary shield then excavatesthe tunnel with the smaller section.

2.3.9. Combined Shields: Mixshield,

Polyshield

Function principle - The closed combinedshield is a machine, which can be adapted todifferent excavating conditions mainly byaltering the excavation face support system.The following combinations have already beenused:l ) air pressure balance _ _ no pressure balance,2 ) slurry pressure balance _ _ no pressurebalance,3 ) earth pressure balance _ _ no pressurebalance,Main components of the machine_ rotating cutterhead (rotates with cutterspokes more or less closed);_ protective shield;_ thrust system:longitudinal jacks.

Main field of application - The versatility ofcombined closed shields lends them to be usedin rocks and soils under the groundwater tablewith limited or no self -supporting capacity.

3. Conditions for TunnelConstruction and Selection of TBMTunneling Method

3.1. Investigations

3.1.1. Introduction

In underground works, construction inducescomplex and often time-dependent soil-structure interaction. Design must thereforedevelop both of the basic aspects, whichdetermine the interaction: statics of theexcavation and the construction methodemployed.

The success of a project, in terms of time andcosts, strongly depends on the method ofexcavation employed and the timing of thevarious construction phases.

The planning of investigation and tests musttake into account these considerations andmust be inserted into a well-defined designplanning.

Figure 3.1 shows the schematic structure ofthe“Guidelines for Design, Tendering andConstruction of Underground Works adoptedby the main Italian Engineering Associationsin relation to tunneling.These“guidelines”a r e based o n theidentification of the“key points”and theirorganization into“subjects”representing thevarious successive aspects of the problem to beanalyzed and quantified during design/ -tendering/construction. The degree of detail ofeach“key point”will depend on the -Peculiarities of the specific project and designstage.In general planning for design, tendering andconstruction, as illustrated in Figure 3.2, thevarious“key points”and“subjects”are linked.The relationship between site investigations(Geological Survey and/or Geotechnical -geomechanical studies) and the Preliminarydesign of excavation and support (Choice ofexcavation techniques and support measures) isindicated.

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F gure 3.1 Schematic structure of the Guidelines for Design, Tendering and Construction ofUnderground Works

1. Main Themes 2. Key points 3. Subjects

_ Functional Requirements_ Design Constraints_ Environmental Aspects_ Comparative analysis of alternative routes

_ Collection and examination of technical documents_ Assessment of the degree of completeness of the design

_ General technical judgment of project and recommendations_ Indication of possible design adjustments_ Considerations regarding possible alternatives_ Special conditions for tendering and construction

_ Literature review

_ Structure_ Stratigraphy_ Geomorphology_ Hydrology and Hydrogeology

_ Evaluation of interaction with geotechnical and geomechanical investigations (C2)_ Planning of site investigations

_ Structural geological setting_ Meso – structural features_ Lithostratigraohic features_ Mineralogical and petrographic features_ Reliability of the qeoloqical model

_ Geomorphological setting_ Interaction between morphogenetic dynamics and designed structures

_ General Hydrology and Hydrogeology_ Water Chemistry_ Structure acquifer interaction_ Presence of other fluids

_ Seismicity of the area and neotectonic aspects

A2.Critical examination of previous design stages

A3.Codes and standards

B1.Acquisition of available data

B2.Preliminary geological model

B3.Site investigations

B4.Final geological model

B5.Geomorphology

B6.Hydrology and hydrogeology

B7.Geothermal studies

B8.Seismicty

GENERALSETTING OF THEUNDERGROUNDWORK

GEOLOGICALSURVEY

A

B

A1.General setting of the works and its relationship with the general design

A4.Reccommendations for subsequent stages of design and construction

Page 72: Recommendations ITA TBM

III-9

4. Main Themes 5. Key points 6. Subjects

_ Review of data from geological study_ Review of data from literature

_ Evaluation of the relation-ship withsite investigation (B3)

_ Planning of investigation and tests_ Summary of results_ Additional investigations

_ Soil and rock-mass structure

_ Soil and intact rock characterization

_ Mechanical characterization of discontinuities

_ Hydraulic properties of soil and rock masses

_ Geomechanical classification of rock masses

_ Geotechnical and geomechanical models

_ Calculation of behavior of face and profile of excavation without support

_ Effects of underground excavations on the surface

_ Effects of excavation on the surrounding mass

_ Effects of tunneling on the existing hydrogeologic equilibrium

_ Study of different methods of excavation and suppout:traditional and mechanized_ Choice of general criteria for construction

C1.Preliminaryl ti

C2.Geotechnical andgeomechanicalinvestigations

C3.Soil or rock masscharacterization

C4.Natural state of stress

D1.Subdivision of the routeinto“homogeneous”zones

D2.Evaluation of the excavationstability conditions for eachhomogeneous zone

D3.Surface and undergroundconstraints

D4.Preliminary design of methods of excavation and

support

GEOTECHNICALGEOMECHANICALSTUDIES

PREDICTION OFMECHANICALBEHAVIOR OF THEMASSES

C

D

Page 73: Recommendations ITA TBM

III-10

y p

_ Definition of applicable methods ofexcavation

_ Definition of section type_ Design of the stabilization interventions

_ Design loads_ Model of construction phases_ Structural design of final lining_ Design of finishing

_ Evaluation of the safety factors_ Crisis scenarios and collapse hypothesis_ Definition of counter measures

_ Design of portals_ Ventilation systems_ Monitoring plan_ Disposal and borrow areas_ Ancillary works_ Construction sites and access roads_ Environmental impact study

_ Technical documents which form part of the contract_ Plan of safety and coordination

_ Geological survey_ Hydrogeological measurements_ Geomechanical measurements_ Monitoring stress-strain response_ Monitoring the state of stress and strain in the lining_ Effectiveness of consolidation and stabilization measures_ Monitoring nearby structures above and below ground

E1.Choice of excavation techniques and support measures for each homogeneous zone

E2.Structural design

E3.Evaluation of safety index

E4.Design optimization

F1.Design of auxiliary works

F2.Tender documents

G1.Monitoring duringconstruction

G2.Checking validity ofdesign and abjustmentsduring construction

DESIGN CHOICESAND CALCULATIONS

DESIGN OFAUXILIARY WORKSAND TENDER

MONITORINGDURINGCONSTRUCTIONAND OPERATION

G3.Auditing

G4.Monitoring during operation

_ Probabilistic evaluation of construction times and costs of the design solution

_ Comparison between design assumption and measurements during construction_ Adjustments of design according to the observed differences

_ Structural auditing_ System auditing

_ Monitoring of stress and strain in ground-stucture complex_ Hydrogeological measurements_ Surveys

G

E

F

Page 74: Recommendations ITA TBM

III-

11

Gen

eral

set

ting

of

wor

ksan

dits

re

lati

onsh

ip

wit

hth

e ge

nera

l des

ign

Cri

tical

cxa

min

atio

n of

prev

ious

des

ign

stag

es

Cod

es a

nd s

tand

ards

Acq

uisi

tion

of

avai

labl

ePr

etim

inar

y ge

olog

ical

mod

elSi

te in

vest

igat

ion

Geo

mor

phol

ogy

Hyd

rolo

gy a

nd h

ydro

geol

ogy

Fina

l geo

logi

cal m

odel

Geo

ther

mal

stu

dies

Rec

com

anda

tions

for

sybs

eque

nt d

es.a

nd c

ons.

Prel

imin

ary

cval

uatio

nG

eote

chni

cal a

nd g

eom

echa

nica

l inv

estig

atio

n

In s

ite s

tres

s

Soil

and

rock

mas

sch

arac

teri

zatio

n

Subd

ivis

ion

into

"hom

ogen

cous

"zon

es

Eva

luat

ion

of e

xaca

vatio

nst

abili

ty f

or e

ach

hom

ogen

eous

zon

em

etho

ds o

f ex

cava

tion

and

supp

ort

Surf

ace

and

unde

rgro

und

cons

trai

nts

Cho

ise

of e

xcav

atio

nte

chni

ques

and

sup

port

mea

sure

sSt

ruct

ural

des

ign

Eva

lutio

n of

the

safe

ly in

dex

Des

ign

optim

izat

ion

Des

ign

of a

uxili

ary

wor

ks

Mon

itori

ng d

urin

gco

nstr

uctio

nC

heck

ing

valid

ity o

fde

sign

and

abj

ustm

ents

Aud

iting

GeologicalGeneral setting ofunderground works

Geotechnical-geomechanical

studies

Prediction of mechanicalbehavior of the masses

Design choiseand calculation

Des

ign

of a

uxili

ary

wor

ks a

nd te

nder

doc

umen

ts

Mon

itori

ng d

urin

g co

nstr

uctio

n an

d op

erat

ion

Mon

itori

ng d

urin

g op

rrat

ion

Tend

er d

ocum

ents

Page 75: Recommendations ITA TBM

III-12

3.1.2. Parameter selection

In line with the general criteria discussed in the previoussection the parameters to be investigated for obtaininguseful information for mechanized tunnel design andconstructionhave been divided in two categories:

1. geological parameters;2. geotechnical - geomechanical parameters.

In the first category, the parameters are common to alltunnel studies and/or design, not restricted to mechanizedtunneling (Table 3.1).

The geotechnical - geomechanical parametersspecifically to mechanized tunneling arepresented in Table 3.2.

In accordance also with the work carried out by theFrench Tunneling Association -(AFTES),the parameters have been divided in different groups:

l. state of stress,2. physical,3. mechanical,4. hydrogeological,5. other parameters.

The following information are reported for each group inTable 3.2:a) the parameter symbol (s)

b) the relationship with TBM excavation, in terms of: _ tunnel face and cavity stability _ cutting head _ cutting tools _ mucking system

c) the stage of the work in which the parameter isrequired, in terms of:

_ FS feasibility study/preliminary design _ DD detailed design _ DC construction stage

d) notes related to particular conditions.

Page 76: Recommendations ITA TBM

III-13

Table 3.1: Geological parameters and investigations required for thedesign of mechanized tunnel excavation

No. OBJECTIVE OF INVESTIGATION INVESTIGATION TYPEGEOLOGICAL

12

Regional structural settingMesostructural and lithostratigraphic features

TopographyPhotogrammetryPhotointerpretationRemote sensingRegional geological studies and mapping

Detailed geological studies and mapping3 Type of soils/rocks Detailed geological studies and mapping

Boreholes4 Soils/rocks structure (fabric, stratification,

fracturing)Detailed geological studies and mappingBoreholes

56

Overburden and layers thickness ,Degree and depth of weathering

Detailed geological studies and mappingGeophysical methodsBoreholes

7 Geological structural discontinuities (faults,shear zones, crushed areas, main joints)

Detailed geological studies and mappingGeophysical methodsBoreholes

8 Special formation (salt, gypsum, tale, organicdeposits)

Detailed geological studies and mapping ,Boreholes

9 Karst phenomena: location of cavities, degreeof karstification, age and origin, infilling andkarst water

Detailed geological studies and mappingSpeleological studiesBoreholesMicro-gravimetric survey

GEOMORPHOLOGY

10 General geomorphological condition TopographyPhotogrammetryPhotointerpretationRegional geomorphological studies and mappingDetailed geomorphological studies and mapping

11 Active or potentially active processes Detailed geomorphological studies and mapping

HYDROLOGY AND HYDROGEOLOGY12

13

Hydrologic condition

Groundwater features ( swampy ground areas,springs or seepage position, notes ongroundwater properties )

TopographyPhotogrammetryPhotointerpretationRegional hydrological studies and mappingDetailed hydrological studies and mappingDetailed geological studies and mappingDetailed hydrogeological studies and mapping

14 No. of groundwater bodies, groundwaterlevels ( and potential groundwater levels )

Detailed hydrogeological studies and mappingBoreholes

15 Soil/rock masses permeability types Detailed hydrogeological studies and mappingGEOTHERMAL CONDITIONS

16 Hydrotermal conditions Regional geological studies17 Gas emanations Regional geological studies and mapping

Detailed geological studies and mappingBoreholes

SEISMICDONDITIONS

18 Seismicity Regional geological studies

Page 77: Recommendations ITA TBM

III-

14

Tab

le 3

.2:

Geo

-Par

amet

ers

rela

ted

to

mec

han

ized

tu

nn

elin

g

Rel

atio

nshi

p w

ith T

BM

exc

avat

ion

Exc

avat

ion

Stag

e of

the

wor

k in

whi

ch th

epa

ram

eter

is r

equi

red

No.

PAR

AM

ET

ER

Sym

bol

Tun

nel f

ace

and

cavi

tyst

abili

tyC

uttin

g he

adC

uttin

g to

ols

Muc

king

syst

emF

SD

DD

CN

OT

E

1ST

AT

E O

F S

TR

ESS

1.1

1.2

1.3

1.4

1.5

Nat

ural

str

ess

Ver

tical

str

ess

Hor

izon

tal/V

ertic

al t

otal

str

ess

ratio

Hor

izon

tal/V

ertic

al e

ffec

tive

stre

ss r

atio

Co

nso

lid

atio

n

deg

ree

(com

pact

ion,

deco

mpr

.)

σ 1,σ

2,σ 3

,σ v

Kt_

(σh/

σ v)

KO

R S/R

S/R S S

S/R

S/R

A A A A

A N N N NO

A-O N

2P

HY

SIC

AL

2.1

Inde

x pr

oper

ties

2.11

2.12

2.13

2.14

2.15

2.16

Vol

umet

ric

wei

ght

Wat

er c

onte

nt, s

atur

atio

n de

gree

, voi

d ra

tioPl

astic

ity i

ndex

Gra

nulo

met

ric

char

acte

rist

ics

Act

ivity

Min

eral

ogic

and

pet

rogr

aphi

c fe

atur

es

γ,γd

,γs,

w, S

i, e

wl,

wn

S/R

S/R S S

S/R

S/R S S

S/R S S/R

S/R

S/R

S/R S

A A A A A A

N-O

N-O

N-O

N-O

N-O

N-O

A A A A A A

Abs

olut

ely

nece

ssar

y in

so

ftgr

ound

2.2

Glo

bal e

valu

atio

n qu

ality

2.21

2.22

2.23

Gen

eral

qua

lity

inde

xA

ltera

tion

inde

xQ

ualit

y in

dex

AM t O

S/R R R

S/R R R

R R

N-O

N-O

A-O

N

2.3

Dis

cont

inui

ties

2.31

2.32

2.33

Dis

cont

inui

ties

dens

ityN

umbe

r of

set

sSe

ts c

hara

cter

istic

s:_

Ori

enta

tion

(dip

and

dip

dir

ectio

n)_

Spa

cing

_ P

ersi

sten

ce_

Rou

ghne

ss_

Ape

rtur

e_

Inf

illin

g_

See

page

_ S

hear

str

engt

h_

Gen

esis

(fo

liatio

n, j

oint

)

RQ

D,λ

Nl,

NX

R R R

R R R

N-O A A

N-O

N-O

N-O

N N N

Page 78: Recommendations ITA TBM

III-

15

Rel

atio

nshi

p w

ith T

BM

exc

avat

ion

Exc

avat

ion

Stag

e of

the

wor

k in

whi

ch th

epa

ram

eter

is r

equi

red

No.

PAR

AM

ET

ER

Sym

bol

Tun

nel f

ace

and

cavi

tyst

abili

tyC

uttin

g he

adC

uttin

g to

ols

Muc

king

syst

emF

SD

DD

CN

OT

E

2.4

Wea

ther

abili

ty

2.41

2.42

2.43

Sens

ibili

ty t

o w

ater

, sol

ubili

tySe

nsib

ility

to

hydr

omet

ric

vari

atio

nsSe

nsib

ility

to

ther

mic

var

iatio

ns

S/R

S/R

S/R

S/R

S/R

S/R

S/R

S/R

A AN

-ON

-O A

A A AN

ot f

requ

ently

use

d

2.5

Wat

er c

hem

istr

y

2.51

2.52

Che

mic

al c

hara

cter

istic

sW

aste

con

ditio

nsS/

RS/

RA

N-O N

A N3

ME

CH

AN

ICA

L

3.1

Stre

ngth

3.11

3.12

3.13

3.14

3.15

Shea

r (s

hort

tim

e)U

niax

ial

com

pres

sive

Tens

ileR

esid

ual

Gen

eral

str

engt

h in

dex

τs f

,σc

σ t, I

S

S/R

S/R R S/R

S/R

S/R

S/R R S/R

S/R

S/R R

N(S

)N

(R)

A-O A

N-O

N-O

N-O

A-O

A A A A A3.

2G

loba

l eva

luat

ion

qual

ity

3.21

3.22

3.23

3.24

Ani

sotr

opy

elas

tic c

onst

ants

Isot

ropi

c el

astic

con

stan

tsV

isco

-beh

avio

rSw

ellin

g

E,υ

E(t

), E

(q)

R S/R

S/R

S/R

R S/R

S/R

N-O A N

A N-O

N-O

N-O

A A A A3.

3D

ynam

ic c

hara

cter

istic

s of

soi

l/roc

k m

ass

3.31

3.32

3.33

P an

d S

wav

es v

eloc

ityD

efor

mab

ility

mod

ules

Liq

uefa

ctio

n po

tent

ial

S/R

S/R S

A A A

N-O

N-O

N-O

A A A

4H

YD

RO

GE

OL

OG

ICA

L4.

14.

24.

34.

4

Ani

sotr

opy

perm

eabi

lity

Isot

ropi

c pe

rmea

bilit

yPi

ezom

etri

c le

vel,

hydr

aulic

gra

dien

tW

ater

flo

w

k X, k

V, k

Z,

k H, i Q

S/R

S/R

S/R

S/R

S/R

N-O N

A-O

N-O

N-O

A-O

N-O

N-O

Page 79: Recommendations ITA TBM

III-

16

Cut

ting

head

Cut

ting

tool

s

5O

TH

ER

PA

RA

ME

TE

RS

5,1

Abr

asiv

ityS/

RS/

RA

-ON

-O5,

2H

ardn

ess

RR

A-O

N-O

All

thes

e pa

ram

eter

s ar

e pa

rticu

larly

5,3

Dril

labi

lity

RN

-Ore

quir

ed f

or m

echa

nize

d tu

nnel

ing

5,4

Stic

ky b

ehav

ior

S/R

S/R

S/R

A-O

N-O

A5,

5G

roun

d fr

ictio

nS/

RA

A-O

A-O

S=So

il; R

=Roc

kFS

=Fea

sibi

lity

Stud

y/Pr

elim

inar

y D

esig

n, D

D=D

etai

led

Des

ign;

DC

=Dur

ing

Con

stru

ctio

nN

=Nec

essa

ry; A

=Adv

isab

le; O

=Qua

ntifi

catio

n of

this

par

amet

er is

don

e th

roug

h sp

ecifi

c te

sts

Exc

avat

ion

Muc

king

syst

em

NO

TE

No.

PAR

AM

ET

ER

Sym

bol

Stag

e of

the

wor

k in

whi

ch t

he p

aram

eter

is

requ

ired

FS

DD

DC

Rel

atio

nshi

p w

ith T

BM

exc

avat

ion

Tun

nel

face

an

d ca

vity

st

abili

ty

Page 80: Recommendations ITA TBM

III-

17

Tab

le 3

.3:

Ge

o-p

ara

met

ers

an

d r

elat

ed i

nves

tig

atio

ns

No .

PA

RA

ME

TE

RIN

VE

ST

IGA

TIO

N T

YP

EL

oca

tio

nS

=si

te

L=

=L

ab.

NO

TE

1S

TA

TE

OF

ST

RE

SS

1.1

1.2

1.3

1.4

1.5

Nat

ural

str

ess

Ver

tica

l st

ress

Ho

rizo

nta

l/V

erti

cal

tota

l st

ress

rat

io

Ho

rizo

ntal

/Ver

tica

l ef

fect

ive

stre

ss r

atio

Co

nso

lid

atio

n

deg

ree

(co

m

acti

on

,d

ecom

pr.)

Bo

reh

ole

Slo

tter

str

essm

eter

met

ho

d (

R)

Ov

erco

rin

g m

eth

od

s (R

)

Hy

dra

uli

c F

ract

uri

ng

Tec

hn

iqu

e (R

) '

Dil

ato

met

er (

S/R

)A

edo

met

er

test

w

ith

la

tera

l p

ress

ure

co

ntr

ol

(S)

Tri

axia

l te

st

wit

h

late

ral

def

orm

atio

n

con

tro

l(S

)D

ilat

om

eter

(S

/R)

Fla

t ja

ck m

etho

d (R

)M

arch

etti

dil

ato

met

er (

S)

Oed

omet

ric

test

(S

)O

edom

etri

c te

st (

S)

S S S S S L L S S S L L

In b

ore

hol

e te

stIn

bo

reh

ole

test

In b

ore

hol

e te

stM

in.

5-6

tes

ts a

re r

equ

ired

, u

sefu

lal

so f

or

soft

ro

ckE

xp

erim

enta

l m

eth

od

No

t fr

equ

entl

y us

edN

ot

freq

uen

tly

used

Ex

per

imen

tal

met

ho

d

2PH

YSI

CA

L2.

1In

dex

prop

ertie

s1.

11

2.12

2.13

2.14

2.15

2.16

Un

it w

eigh

t

Wat

er

con

ten

t,

satu

rati

on

d

egre

e,

void

inde

xP

last

icit

y i

nde

xG

ranu

lom

etri

c ch

arac

teri

stic

s

Act

ivit

yM

iner

alo

gic

an

d p

etro

grap

hic

fea

ture

s

Den

sity

tes

ts (

S/R

)G

amm

a-d

ensi

met

er (

S)

Lab

ora

tory

in

dex

tes

ts (

S/R

)A

tter

berg

lim

its

(S)

Gra

in-s

ize

anal

yse

s an

d

sed

imen

tati

on

anal

yse

s (S

)P

etro

grap

hic

an

aly

ses

(R)

Min

eral

og

ic a

nal

yse

s (S

)M

iner

alo

gic

an

aly

ses

(S/R

)P

etro

grap

hic

an

aly

ses

(S/R

)C

hem

ical

an

aly

ses

(S/R

)

L S L L L L L L L L

2.2

Glo

bal e

valu

atio

n of

qua

lity

2.21

2.22

Gen

era

qual

ity

inde

x

Alt

erat

ion

inde

x

Geo

ph

ysi

cal

met

hods

: .s

eism

ic,

geo

elec

tric

,m

icro

gra

vim

etri

c, g

eora

dar

(S

/R)

Bo

reh

ole

per

fora

tio

n

par

amet

ers:

ve

loci

ty,

torq

ue,

pre

ssu

re (

S/R

)V

isu

al e

xam

inat

ion

of

the

mat

eria

l (R

)S

lake

du

rab

ilit

y te

st (

R)

S S S L

Qu

alit

ativ

e ev

alua

tion

Ou

tcro

ps,

inve

stig

atio

n ga

ller

ies,

bo

reh

ole

sam

ple

s

Page 81: Recommendations ITA TBM

III-

18

No.

PAR

AM

ET

ER

INV

EST

IGA

TIO

N T

YPE

Lo_a

tion

S=si

teL

=Lab

NO

TE

2,23

Qua

lity

inde

xSo

nic

wav

es te

st (R

)L

Min

eral

ogic

al a

naly

sis

(R)

LPe

trogr

aphi

c an

alys

is (

R)

L2,

3D

isco

ntin

uitie

s2,

31D

isco

ntin

uitie

s den

sity

Site

mea

sure

men

ts (

R)

SO

utcr

opR

ock

Qua

lity

Des

igna

tion-

RQ

D (R

)S/

LB

oreh

ole

sam

ples

Seis

mic

_ur

vey(

R)

SQ

ualit

ativ

eev

alua

tion

2,32

Num

ber

ofse

tsSi

te m

easu

rem

ents

+ s

tere

ogra

phic

ana

lyse

s (R

)S/

L2,

33Se

ts c

hara

cter

istic

s:1.

Orie

ntat

ion

(dip

and

dip

dire

ctio

n)1.

Site

mea

sure

men

t1.

S2.

Spac

ing

2. S

ite m

easu

rem

ent

2.S

3. P

ersi

sten

ce3.

Site

mea

sure

men

t3.

S_.

Rou

ghne

ss4.

Site

mea

sure

men

t4.

S5.

Ape

rture

5. S

ite m

easu

rem

ent

5.S

6.In

fillin

g6.

Site

obs

erva

tion

and_

min

eral

ogic

al te

st6.

S7.

Seep

age

7. S

ite m

easu

rem

ent

7.S

8.

Shea

r st

reng

th8.

Shea

rtes

t8.

L9.

Gen

esis

(fol

iatio

n, b

eddi

ng, j

oint

)9.

Geo

logi

cal o

bser

vatio

ns9.

S2,

4W

eath

erab

ility

2,41

Sens

itivi

ty to

wat

er, s

olub

ility

Site

obs

erva

tion

(S/R

)S

Min

eral

ogic

al a

naly

ses

(S/R

)L

Swel

ling

test

(R)

Let

c.)C

yclic

test

s (w

et-d

ry) (

R)

LSo

lubi

lity

test

(R)

L2,

42Se

nsib

ility

to h

ygro

met

ric v

aria

tions

Min

eral

ogic

ana

lyse

s (S

/R)

LSi

te o

bser

vatio

n (S

/R)

S2,

43Se

nsib

ility

to th

erm

ic v

aria

tions

Hea

ting

test

(S/R

)L

Free

zing

test

(S/R

)L

2,5

Wat

er c

hem

istry

2,51

Che

mic

alch

arac

teris

tics

Che

mic

al a

naly

ses:

sal

t co

nten

t, a

ggre

ssiv

ity,

Lha

rdne

ss, p

H v

alue

, tem

pera

ture

, etc

.2,

52w

aste

con

ditio

nsC

hem

ical

ana

lyse

sL

3M

EC

HA

NIC

AL

3,1

Stre

ngth

3,11

Shea

r (s

hort

time)

Cas

agra

nde

shea

r bo

x te

st, u

ndra

ined

con

ditio

ns (

S)S/

LD

irect

She

ar te

st (R

)L

In s

itu d

irect

she

ar te

st (

R)

STr

iaxi

al te

st (S

/R)

S/L

Soils

: l

ower

lim

it va

lues

; r

ocks

: u

pper

lim

it va

lues

Scis

som

eter

/ V

ane

test

(S)

S/L

Incl

ayed

bore

hole

sam

ples

Page 82: Recommendations ITA TBM

III-

19

No.

PA

RA

ME

TE

RIN

VE

STIG

AT

ION

TY

PE

Loc

atio

nS=

site

L=

Lab

NO

TE

3,12

Uni

axia

l co

mpr

essi

veU

niax

ial

com

pres

sion

tes

t (S

/R)

LPo

intl

oad

test

(R)

S/L

Indi

rect

mea

sure

men

t of

the

par

amet

er3,

13T

ensi

leD

irec

t ten

sile

test

(R

)L

Bra

zili

ante

st(R

)L

Indi

rect

mea

sure

men

t of

the

par

amet

erPo

intl

oad

test

(R)

S/L

_ndi

rect

mea

sure

men

t of

the

par

amet

er3,

14R

esid

ual

Res

idua

l st

reng

th t

est

(she

ar, t

riax

ial

test

s)S/

L3,

15G

ener

al s

tren

gth

inde

xB

oreh

ole

per

fora

tion

pa

ram

eter

m

easu

rem

ents

:ve

loci

ty, t

orqu

e, p

ress

ure

(S/R

)3.

,2D

efor

mab

ility

3,21

Isot

ropi

c/A

niso

trop

icel

_stic

cons

tant

sPl

ate

load

ing

test

(R

/S)

SR

ock

surf

ace

test

Dir

ectio

nal d

ilato

met

er te

st (

S/R

)S

Insi

debo

reho

lete

sts

Uni

axia

l -T

riax

ial

com

pres

sive

tes

ts o

n di

rect

iona

lL

sam

ples

(S/

R)

P-S

wav

e m

easu

rem

ent

(_/R

)S/

LQ

uali

tati

vem

easu

rem

ent

Def

orm

atio

n m

easu

rem

ent

(S/R

):S

Roc

k su

rfac

e te

st (

i.e. e

xper

imen

tal-

_. C

onve

rgen

ce/d

ilata

ncy

galle

ry)

2.

Ext

enso

met

er3.

In

clin

ome_

ers

4. S

ettle

men

ts3,

22V

isco

-beh

avio

rFl

at ja

ck m

etho

d (R

)S

Roc

ksu

rfac

ete

stL

ong-

time

plat

e lo

adin

g te

st (

R)

SR

ock

surf

ace

test

C

reep

load

test

(S)

LC

ycle

dila

tom

eter

test

(S/

R)

SIn

side

bore

hole

test

s_e

form

atio

n m

easu

rem

ents

(S/

R)

SR

ock

surf

ace

test

3,23

Swel

ling

Swel

ling

test

(S/R

)L

/S3,

3D

ynam

ic c

hara

cter

isti

cs o

f so

il/r

ock

mas

s3,

31P

and

S w

aves

vel

ocity

Seis

mic

sur

vey:

cro

ss-h

ole,

dow

n-ho

leS

Insi

debo

reho

lete

s_s

3,32

Def

orm

abili

tym

odul

esSe

ism

ic s

urve

y: c

ross

-hol

e, d

own-

hole

SIn

side

bor

ehol

e te

sts

3,33

Liq

uefa

ctio

npo

tent

ial

Stan

dard

pen

etra

tion

tes

tS

Insi

debo

reho

lete

sts

4H

YD

RO

GE

OL

OG

ICA

L4,

1A

niso

trop

icpe

rmea

bilit

yO

bser

vatio

n du

ring

bor

ehol

e dr

illin

gS

Qua

litat

ive

dete

rmin

atio

nPe

rmea

bilit

yte

sts:

SIn

side

bor

ehol

e te

ests

1.

Lef

ranc

2.

Lug

eon

3. D

irec

tiona

l, co

nsta

nt o

r va

riab

le w

ater

leve

l

Page 83: Recommendations ITA TBM

III-

20

No.

PAR

AM

ETER

INV

ESTI

GA

TIO

N T

YPE

Loca

tion

S=sit

eL=

Lab

NO

TE

4.2

Isot

ropi

c pe

rmea

bilit

yPu

mpi

ngte

stS

Inje

ctio

n te

st S

4.3

Piez

omet

ric le

vel,

hydr

aulic

gra

dien

tPi

ezom

eter

(ope

nty

pe)

S P

iezo

met

er (c

lose

type

)S

4.4

Wat

er fl

ow

Tunn

el m

easu

rem

ents

S S

prin

gs m

easu

rem

ents

S

OTH

ER P

AR

AM

ETER

S5.

1A

bras

ivity

Abr

asiv

ity IS

RM

LC

erch

ar te

st (R

)L

Abr

asiv

ity (N

orw

egia

n In

stitu

re o

f Tec

hnol

ogy)

LLC

PT te

st (S

/R)

L5.

2

H

ardn

ess

Har

dnes

s IS

RM

(R

)L

Schm

ith h

amm

er (

R)

LLC

PT te

stL

Kno

opS/

LC

one

Inde

nter

test

(NC

B)

LPu

nch

test

(Col

orad

o Sh

ool o

f Min

es)

LD

rop

test

(Nor

weg

ian

Inst

itute

of T

echn

olog

y)L

Los A

ngel

es te

st (S

/R)

L5.

3D

rilla

bilit

y Si

ever

’ste

stL

Dril

labi

lity

tests

L5.

4St

icky

beh

avio

rM

iner

alog

ical

ana

lyse

s (S

/R)

LIn

dire

ct m

easu

rem

ent,

rela

ted

with

A

tterb

erg

limits

(S)

Lph

ysic

alin

dex

prop

ertie

s

Page 84: Recommendations ITA TBM

III-21

In Table 3.3 an international standard is given for each investigation or test related to mechanized tunneling.Table 3.3: Investigations, test methods and references

METHODS REFERENCESITE INVESTIGATIONTopography,aerotopography,photogrammetryphotointerpretationEngineering geological investigationsGeophysical methods:_ micro-gravity_ seismic_ geoelectric_ georadarDrilling,borehore cameras and televisionTrenches,shafts and galleries

ISRM 1975

ISRM 1975

ASTM D4428-84

SITE TESTPlate loading test (R)Overcoring methods (R)Flat jack method (R)Hydraulic fracturing method (R)Compression Test (R)Direct shear test (R)Dilatometer (S/R)Standard penetration test: SPT (S)Cone penetration test: CPT (S)Rock Quality Designation (RQD)Vane Shear Test (S)Discontinuities (R)Deformation measurements (S/R):1. Convergence/dilatancy2. Extensometer3. Inclinometers4. SettlementsLong-time plate bearing test (R)Creep test (S/R)Cycle dilatometer test (S/R)Deformation measurements (S/R)Permeability tests:1. Lefranc2. Lugeon3. Directional, constant or variable, water levelPumping testInjection testPiezometer (open type)Piezometer (close type)Tunnel measurements

ISRM11 / ISRM19 / ASTM D4394-84 / ASTM D4395-84ASTM D4623-86ASTM D4729-87ASTM D4645-87ASTM D4555-90

ASTM D4971-89 / ASTM D4506 -90ASTM D1586-84 / ASTM D4633 - 86ASTM D3441-86

ASTM D2573-72ISRM07 / ISRM14 / ASTM D4554 - 90

ASTM D4553-90

ASTM D2434-68

ASTM D4750-87

LABORATORY - SOILIdentification tests :_ Volumetric weights (natural, dry, satured)_ natural water content, saturation degree_ porosity, void ratio_ Atterberg limits_ Activity (clay)

ASTM D4318-84 / ASTM D4254-83 / ASTM D3282-88ASTM D2487-90 / ASTM D4404-84 /ASTM D4959-89 / ASTM D854-83ASTM D427-83 / ASTM D2210-90

Page 85: Recommendations ITA TBM

III-22

METHODS REFERENCE

Grain-size analyses and sedimentation analysesGamma-densimeterMineralogic analyses (diffractometer)Chemical analysesPermeabilityOedometric test:_ Natural consolidation_ compressibility characteristics (consolidation

index, edometric compressibility index)_ permeability_ swelling pressure/ swelling indexswelling test (Huder-Amberg)Shear test:_ total coesion_ total frictional angleTriaxial test:_ drained coesion_ drained frictional angle_ undrained coesion_ total coesion_ total frictional angle

ASTM D422-63 / ASTM D2487-90 / ASTM D1140-54

ISRM 1977 / ASTM D4452-85

ASTM D2438-90ASTM D4186-90 / ASTM D2435-90 / ISRM 89ASTM D2435-90 / ASTM D2166-85

ASTM D3080-90 / ASTM D2435-90

ASTM D4767-88 / BS1377 / ASTM D2850-87

LABORATORY - ROCKIndex laboratory tests:_ Density_ natural water content_ porositySlake durability testPetrographic analysesMineralogic analysesChemical analysesUniaxial compression test (R)Point load test (R)Triaxial test (R)

Direct Shear test (R)Direct tensile test (R)Brazilian test (R)CreepSonic waves test (R)Swelling test (R)Cyclic tests (wet-dry) (R)Solubility test (R)Thermal expansion test (S/R)Frozing test (S/R)Abrasivity_ Abrasivity_ Cerchar test (CAI index)_ Abrasivity test (AV – AVS)Hardness_ Hardness_ Schmith hammer_ Knoop_ Cone Indenter (INCB)_ Punch test_ Los Angeles test (S/R)

ISRM09

ISRM09 / ASTM D4644-87ISRM01

ISRM08 / ASTM D3148-86 / ASTM D2938-86ISRM16 / ISRM25ISRM02 / ISRM13 / ASTM D2664-86ASTM D4767 / BS1377 / AGI 1994ISRM05 / ASTM D2936-84 / ASTM D3967-86ISRM24

ASTM D4341-84 / ASTM D4406-84 / ASTM D4405-84ASTM D2845-90 / ISRM03ISRM09

ASTM D4611-86

ISRM04West 1989NIT 1990

ISRM04ISRM 1977

National Coal Board, UK, 1964

Page 86: Recommendations ITA TBM

III-23

METHODS REFERENCEDrillability

• Sievers test NIT 1990

• Drillability test

• Resistance to crushing : Drop test NIT 1990

LABORATORY - WATERChemical analyses:_• salt content / organic materials Standard Methods for examination of wa

• aggressivity_ waters. American Public Health Associa

• hardness• pH value

• temperature

Page 87: Recommendations ITA TBM

III-24

3.1.3. Monitoring during construction

The deterministic design of a tunnel is based onjudgment in selecting the most probablevalues within the ranges of possible values ofengineering properties. As construction -progresses the geotechnical - geomechanical conditionsare observed, work performance ismonitored and the design judgments can be evaluatedor, if necessary, updated. Thus,engineering observations during tunnel works are oftenan integral part of the design process,and geotechnical - geomechanical -instrumentation is a tool, which assists with theseobservations.

From a general point of view, the scope of themonitoring scheme is to:

A. control the stability and stress - strain conditions ofthe structures in the new underground construction;

B. control the stability and stress-strain conditions ofthe existing structures which potentially interfere withthe new construction; and

C. control ground movement around the newunderground constructions;

D. monitor environmental aspects.

The design of the general monitoring scheme comprisesthe following activities:

1. identification of the significant parameters whichneed to be monitored in consideration of: _ construction geometries and materials; _ stability of existing structures (surface and/or

underground) and their potentialinterference with the new construction;

_ geotechnical – geomechanical parameters of theground and their range of variation;

_ geo-structural calculations and structural analysis;and

_ construction sequence.

2. definition of the adequate types of instruments;

3. specification of the caution and alarm values for eachparameter to be monitored;

4. definition of the counter – measures in case thatcaution and/or alarm leveis are exceeded.The different investigation/monitoring possibilities are _ from ground surface, or from underground _ before, during and after excavation.In the following subsections we will only examine theunderground investigation/-monitoring systems specifically related to TBMtunneling (investigation before -excavation and monitoring during excavation from

underground).

3.1.4. TBM tunneling monitoring system

Monitoring systems are used to study the stress-strainbehavior of the surrounding ground and lining duringand after -construction.

The use of a TBM for the construction of a tunnel doesnot permit continuous, directobservation of the ground being excavated.Therefore, all the necessary geological-geomechanical information required both during theconstruction phase for evaluating the ground conditionsahead of the excavation face and subsequently for thepurpose ofdocumentation when the work is completed, arenormally obtained using indirect methods.

Usually the studies on the interaction between thesoil/rock mass and the TBM aim tocharacterize the quality of the ground mass, above all,to assess its borability.

However, the current problem is an inverse one: giventhat there is no question that the groundcan be excavated, efforts must be focused on thecharacterization itself through analysis andelaboration of all construction parameters that couldpossibly be recorded.

Through precise and objective documentation of whatthe TBM encounters during excavationit is possible to derive the principal -characteristics of the soil/rock mass because variationsin TBM behavior are usually correlated with changes inthe geotechnical-geomechanicalsituations.

It is important to underline right from the outset that theprerequisites for making a correctevaluation of the ground mass using all the constructionparameters that can possibly berecorded may be summed up as follows:_ the use of a TBM fitted with appropriate

instrumentation._in this approach skilled engineering geologists with

experience should be employed to collect andinterpret all the relevant data.

_ The data collected should be stored in a dynamicdatabase so that multiple-parametercorrelation can be not only established but alsocontinuously updated in quasi-real time, as well asoffering the possibility to carry out ground conditionsextrapolation and forecasting.

From a tunnel excavated by TBM it is possible toinvestigate the ground ahead of the tunnelface using the methods listed it Table 3.4.

Page 88: Recommendations ITA TBM

III-25

The TBM monitoring systems which can be used tocollect data during tunnel construction are listed inTable 3.5.

Page 89: Recommendations ITA TBM

III-26

Table 3.4: Types of soil/rock mass investigations used ahead TBM face

INVESTIGATION TYPE NOTE

Direct investigation

Boreholes with core recovery Horizontal boreholes are normally performed through the TBMcutting head; inclined boreholes are normally possible immediatelybehind the cutting head in open TBM, through the shield in shieldedTBM. Radial boreholes are possible in all TBM types through thelining.

The objective of boreholes is to:

_ determine the lithological nature of the ground to be excavatedthrough by the TBM.

_ determine the presence of water_ determine thepresence of voids (karst) and/or decompressed

zones;

The drilling is realized with a rig positioned behind the TBM cuttinghead. In the case of shielded TBMs, it is also possible to utilizea“preventer”system to avoid the ingress of groundwater to the tunnelduring execution of the drilling.

Horizontal and/or inclined boreholes with core-recovery is notcommonly used because the time and drilling diameter required.

Boreholes without core recovery The method of no-core-recovery with registration of the followingdrilling parameters using a data-logger.

_ drilling rate (VA, m/h) ;_ pressure on drill bit (PO,bar) ;_ pressure of the drilling fluid (PI, bar) ;_ torque (CR, bar) ;

It is possible to use either a drilling hammer or a tricone bit. Thediameter of the drill hole may be limited to 75mm, whereas thedrilling rods may be of the aluminum type in order to reduce potentialproblems associated with the advance of the TBM later in the casethat the drilling rods might be completely lost in the drill hole.

Geostructural mapping of the face and/orof the sidewalls

The mapping must be performed using the same methodologiesadopted for the face mapping in tunnels excavated by conventionalmethods.

This type of investigation can be performed only when the TBM stopsexcavation and thus it can be executed at more or less regularintervals in function of the various construction needs. The mappinginvolves the collection of all geological, structural and geomechanicaldata of the soil/rock mass. The purpose of this kind of investigationis:

_ direct characterization and classification of the soil/rock mass;_calibration of all construction parameters which may permit indirect

characterization of the rock mass.Indirect investigation

Georadar (in borehole)

Other borehole logs Gamma ray logNeutron logsGeoelectric logs

Seismic methods Tunnel Seismic Prediction method (TSP)Soft Ground Sonic Probing System (SSP)

Table 3.5: TBM monitoring systems

Page 90: Recommendations ITA TBM

III-27

Category Parameter UdM TBMtype

Power kW

Torque Knm

Thrust KN

Rotation speed RPMCut

ting

head

Penetration rate mm/s

Consumption -

Exc

avat

ion

Cutting

tools Wedge position mm

All TBM

Air pressure kPa

Air discharge m3/h

Closed slurry shield (hydroshield)Compressed air close shield

Slurry pressure kPa

Slurry level mmClosed slurry shield

Supp

ort i

n th

e

exca

vatio

n

cham

ber

Earth pressure kPa Earth pressure balance shield

Slurry discharge m3/h

Slurry density kg/dm3

Discharge m3/h

Density kg/dm3

Closed slurry shield

Weight kN

Am

ount

Amount m3

Unshielded, single-double shielded TBM, mec.supported, comp. air, closed slurry and EPB shields

Petrographic characteristics -

Grain-size distribution -

Muc

king

Cha

ract

.

mechanical parameters -

All TBM (in slurry shield or EPB shield TBM is not required)

Shield position (x y z) m All TBM

Gripper thrust kN

Gripper stroke mm

Open TBM and some doubleshielded TBM

Jack thrust kN

Jacks stroke mm

Single-double shielded TBM, mec. suppoted, comp.

air, closed slurry and EPB shields TBM

Injection (through the shield) pressure kPa

Injection (through the shield) amount m3Closed slurry and EPB shield

Concrete injection pressure kPa

Oth

er p

aram

eter

s

Concrete injection amount m3

Shielded TBM with extrudedconcrete lining system

Excavation cycle (min. - med. - max.) h

Advance rate per shift/day/week/month m

Perf

orm

ance

Lining rings per shift/day/week/month N°

Planned (holidays, tools change, other ordinarymaintenance) h

Due to machine problem (mechanical, electrical, etc.) h

Due to unpredicted rock mass behavior, (water inflow,tunnel face and /or cavity instabilities, squeezing ground,karst, etc.) h

Due to lining problems h

Diverse (back-up problems, others) h

Con

stru

ctio

n da

ta

TB

M s

tops

Due to mucking system problems (slurry circuit, screwconveyor, belt conveyor, muck cars, etc.) h

All TBM

Page 91: Recommendations ITA TBM

III-28

4. REFERENCES

A) ASTM (American Society for TestingMaterials)

D4750-87“Subsurface Liquid Levels in aBorehole or Monitoring Well(Observation Well ) ,Determining”.

D1140-54“Amount of Material in Soils Finerthan the No. 200 (75-_m) Sieve”.

D4428-84“Crosshole Seismic Testing”.D2487-90“Classification o f Soi ls for

Engineering Purposes”.D2166-85“Compressive Strength, Unconfined,

of Cohesive Soil”.D4767-88“Consolidated-Undrained Triaxial

Compression Test on CohesiveSoils”.

D4404-84“Determination of Pore Volume andPore Volume Distribution of Soiland Rock by Mercury IntrusionPorosimetry”.

D4959-89“Determination of Water (Moisture)Content of Soil by Direct HeatingMethod”.

D4829-88“Expansion Index of Soils”.D2573-72“Field Vane Shear Test in Cohesive

Soil”.D4318-84“Liquid Limit, Plastic Limit, and

Plasticity Index of Soils”.D2435-90“One-Dimensional Consolidation

Properties of Sails”.D4186-90“One-Dimensional Consolidation

Properties of Soils UsingControlled-Strain Loading” .

D2434-68“Permeability of Granular Soil(Constant Head)”.

D4719-87“Pressuremeter Testing in Soil”.D2844-89“Resistance R-Value and Expansion

Pressure of Compacted Soils”.D427-83 “Shrinkage Factors of Soils”.D854-83 “Specific Gravity of Soils”.D2850-87“Unconsolidated,Undrained

Compressive Strength of CohesiveSoils of Cohesive Soils in TriaxialCompression”.

D3441-86“Deep, Quasi-Static, Cone andFriction-Cone Penetration Testsof Soil”.

D3080-90“Direct Shear Test of Soils UnderConsolidated Drained -Conditions”.

D422-63“Particle-Size Analysis of Soils”.

D2216-90“Water (Moisture) Content of Soil,Rock, and Soil-Aggregate -Mixtures, Laboratory -Determination of ...”.

D4452-85“X-Ray Radiography of Soil -Samples”.

D4341-84“Creep of Cylindrical Hard RockCore Specimens in UniaxialCompression”.

D4406-84“Creep of Cylindrical Rock CoreSpecimens in Triaxial -Compression”.

D4405-84“Creep of Cylindrical Soft RockCore Specimens in UniaxialCompression”.

D4555-90“Deformability and Strength ofWeak Rock by Conducting an InSitu Uniaxial Compressive Test,Determining”.

D497l-89“Determining the In Situ Modulus ofDeformation of Rock UsingDiametrically Loaded 76-mm (3-in.) Borehole Jack”.

D2936-84“Direct Tensile Strengh of IntactRock Core Specimens”.

D3148-86“Elastic Moduli of Intact Rock CoreSpecimens in Uniaxial -Compression”.

D4553-90“In Situ Creep Characteristics ofRock,Determining”.

D4554-90“In Situ Determination of DirectShear Strength of Rock -Discontinuities”.

D4395-84“In Situ Modulus of Deformation ofRock Mass Using the FlexiblePlate Loading Method,Determining”.

D4506-90“In Situ Moudulus of Deformationof Rock Mass Using a RadialJacking Test, Determining”.

D4394-84“In Situ Modulus of Deformation ofRock Mass Using the Rigid PlateLoading Method, Determining”.

D4623-86“In Situ Stress in Rock Mass byOvercoring Method - USBMBorehole Deformation Gage,Determination of ...”.

D4729-87“In Situ Stress and Modulus ofDeformation Determination Usingthe Flat jack Method”.

D4645-87“In Situ Stress in Rock Using theHydraulic Fracturing Method”.

D4644-87“Slake Durability of Shales andSimilar Weak Rocks”.

Page 92: Recommendations ITA TBM

III-29

D4611-86“Specific Heat of Rock and Soil”.D3967-86“Splitting Tensile Strength of Intact

Rock Core Specimens”.D2664-86“Triaxial Compressive Strength of

Undrained Rock Core SpecimensWithout Pore Pressure -Measurements”.

D2938-86“Unconfined Compressive Strengthof Intact Rock Core Specimens”.

D2845-90“Laboratory Determination of PulseVelocities and Ultrasonic ElasticConstants of Rock”.

B) ISRM (International Society of RockMechanic)

ISRM01“Suggested methods for petrographicdescription of rocks”. 1978,International Journal of RockMechanics. Mining Sciences andGeomechanical Abstract,vol. 15,n_2,pp. 41-46.

ISRM02“Suggested methods for determiningstrength of rock materials in triaxialcompression”. 1978, InternationalJournal of Rock Mechanics, MiningSciences a n d GeomechanicalAbstract, vol.15, n_2, pp. 47.52.

ISRM03“Suggested methods for determiningsound velocity”. 1978,InternationalJournal of Rock Mechanics, MiningSciences a n d GeomechanicalAbstract, vol.15,n_2, pp. 53-58.

ISRM04“Suggested methods for determininghardness and abrasiveness of rocks”.1978, International Journal of RockMechanics, Mining Sciences andGeomechanical Abstract, vol.15,n_2,pp. 89-98.

ISRM05“Suggested methods for determiningtensile strength of rock materials”.1978,International Journal of RockMechanics, Mining Sciences andGeomechanical Abstract, vol.15,n_2,pp.-99-104.

ISRM06“Suggested methods for monitoringrock movements using boreholeextensometers”. 1978, InternationalJournal of Rock Mechanics, MiningSciences and Geomechanical -Abstract, vol. 15, n_6, pp. 305-318.

ISRM07“Suggested method f o r thequantitative description of -discontinuities in rock masses”.

1978, International Journal of RockMechanics, Mining Sciences andGeomechanical Abstract, vol. 15,n_6, pp. 319-368.

ISRM08“Suggested methods for determiningthe uniaxial compressive strength anddeformability of rock materials”.1979, International Journal of RockMechanics, Mining Sciences andGeomechanical Abstract, vol.16,n_2,pp. 135-140.

ISRM09“Suggested methods for determiningwater content, porosity, density,absorption, and related properties andswelling and slake-durability indexproperties”. 1979, InternationalJournal of Rock Mechanics,MiningSciences and Geomechanical -Abstract, vol. l6, n_2, pp. 141-l56.

ISRM10“Suggested methods for determiningin situ deformability of rock”. 1979,International Journal of RockMechanics, Mining Sciences andGeomechanical Abstract, vol.16,n_3,pp. 195-214.

ISRM11“Suggested methods for pressuremonitoring using hydraulic cells”.1980, International Journal of RockMechanics, Mining Sciences andGeomechanical Abstract, vol. 17,n_2, pp. 117-128.

ISRM12“Suggested methods for geophysicallogging of boreholes”. 1981,International Journal of RockMechanics, Mining Sciences andG e o m e c h n i c a l Abstract,vol.18,n_1,pp.67-84.

ISRM13“Suggested methods for determiningthe strength of rock materials intriaxial compression: revised -version”. 1983, International Journalof Rock Mechanics, Mining Sciencesand Geomechanical Abstract, vol. 20,n_6, pp. 283-290.

ISRM14“Suggested methods for surfacemonitoring movements acrossdiscontinuities”. 1984, InternationalJournal of Rock Mechanics, MiningSciences and Geomechanical -Abstract, vol. 21 , n_5, pp. 265-276.

ISRM15“Suggested methods for pressuremonitoring using hydraulic cells”.1985, International Journal of RockMechanics, Mining Sciences and

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Geomechanical Abstract, vol. 22,n_2, pp. 51-60.

ISRM16“The equivalent core diameter methodof size and shape correction is pointload testing”. 1985, InternationalJournal of Rock Mechanics, MiningSciences a n d GeomechanicalAbstract, vol. 22, n_2, pp. 61-70.

ISRM17“Suggested methods for rocka n c h o r a g e testing”. 1985,International Journal of RockMechanics, Mining Sciences andGeomechanical Abstract,vol. 22, n_2,pp. 71-84.

ISRM18“Suggested methods for deformabilitydetermination using a large flat jacktechnique”. 1986, InternationalJournal of Rock Mechanics, MiningSciences and Geomechanical -Abstract, vol. 23, n_2, pp.131-140.

ISRM19“Suggested methods for rockdetermination”. 1987, InternationalJournal of Rock Mechanics, MiningSciences a n d GeomechanicalAbstract, vol. 24, n_ 1, pp. 53-74.

ISRM20“Suggested methods for deformabilitydetermination using a flexibledilatometer”. 1987, InternationalJournal of Rock Mechanics, MiningSciences a n d GeomechanicalAbstract, vol. 24, n_2, pp. 123-134.

ISRM21“Suggested methods for determiningthe fracture toughness or rock”. 1988,International Journal of RockMechanics, Mining Sciences andGeomechanical Abstract, vol. 25, n_2,pp. 71-96.

ISRM22“Suggested methods for seismictesting within and betweenboreholes”. 1988, InternationalJournal of Rock Mechanics, MiningSciences and Geomechanical -Abstract, vol. 25, n_6, pp. 447- 472.

ISRM23“Suggested methods for deformabilitydetermination using a large flat jacktechnique”.

ISRM24“Suggested methods for determingShear Strength”. February 1974.

C) OTHER REFERENCES

ITA (International Tunneling Association),

1987, “Guidelines for Good TunnelingPractice”.

BTS (British Tunneling Society), 1997,“Model Specification for Tunneling”.

AFTES (Association Francaise des Travaux enSouterrain)

_Text of recommendations for a descriptionof rock masses useful for examination thestability of underground works (WorkingGroup n . l : Geology-geotechnicalengineering). 1993;

_Proposals concerning the measurementsand testing to be performed in connectionwi th a mechanical cut t ing :characterization of rocks and soils(Working Group n.4: Mechanizedexcavation), 1993.

SIG (Società Italiana Gallerie), 1997,“National Project for Design andConstruction Standards in UndergroundWorks Guidelines for Design, Tenderingand Construction of Underground Works”,Gallerie e Grandi Opere Sotterranee,marzo 1997.

AGI (Associazione Geotecnica Italiana), 1977,“Raccomandazioni sulla programmazioneed esecuzione delle indagini geotecniche”.

AGI (Associazione Geotecnica Italiana),1994,“Raccomandazioni sulle prove - geotecniche di laboratorio”.

SIA (Société Suisse des Ingégneurs et desArchitects), 1975, “Norma 199 conoscenzadei massicci rocciosi nei lavorisotterranei”. Zurich.

SIA (Société Suisse des Ingégneurs et desArchitects),1993, “NORMA 198 Lavori insotterraneo”. Zurich.

AUSTRIAN NORM, 1983, “ONORM2203”and “VORNORM 2203”, 1975.

D E U T S C H E R AU S S C H U S S FÜRUNTERIRDISCHES BAUE N: DAUB;ÖSTERREICHISCHE

GESELLSCAFT FÜR GEOMECHANIKUND ARBEITSGRUPPE TUNNELBAUDER FORSCHUNGESELLSCHAFT FÜRDAS VERKEHRS – UND -STRASSENWESEN: FACHGRUPPPE

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FÜR UNTERTAGEBAU DES -SCHWEIZERISCHEN INGENIEUR - UNDARCHITEKTENVHREIN,1996, Empefelung zur Auswal undBewentung von Tunnelvotriebsmachinen.Vol. Spec.

GEHRING K.H., 1995, “Deciding aboutRange of Application for Shield System,Prerequisites,Concepts, Examples”. Attidel la giornata d i studio: “Scavomeccanizzato integrale delle gallerie.Progettazione integrata e criteri di sceltadelle macchine”. Roma.

NATIONAL COAL BOARD (NCB), 1964,“Methods of assessing rock cuttability”,C.E.E. Report, N_ 65 ( 1 ).

NIT - NORWEGIAN INSTITUTE OFTECHNOLOGY, 1988, “Hard rock tunnelboring”. General Report.

NIT - NORWEGIAN INSTITUTE OFTECHNOLOGY, 1990, “Drillabilily, drillingrate index catalogue”, PR 13.90 Universityof Trondheim.

PACHER F., RABCEWICZ L.V., GOLSER J.,1974, Zum derzeitigem Stand derGebirgsklassifizierung in Stollen - undTunnelbau. Preference S 1-8.

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AFTESNEW RECOMMENDATIONS ON

CHOOSING MECHANIZED TUNNELLING TECHNIQUES

TEXT PRESENTED BYP. LONGCHAMP, MODERATOR OF AFTES WORK GROUP NO. 4 - TECHNICAL MANAGER, UNDERGROUND WORKS -

BOUYGUES TRAVAUX PUBLICS

WITH THE ASSISTANCE OF A. SCHWENZFEIER, CETU

THESE SUBGROUPS WERE MODERATED BY

J.M. DEMORIEUX, SETEC - F. MAUROY, SYSTRA - J.M. ROGEZ, RATP - J.F. ROUBINET, GTMTHESE RECOMMENDATIONS WERE DRAWN UP BY A NUMBER OF SUB WORK GROUPS WHOSE MEMBERS WERE:

A. AMELOT, SPIE BATIGNOLLES - D. ANDRE, SNCF - A. BALAN, SNCF - H. BEJUI=, AFTES -F. BERTRAND, CHANTIERS MODERNES - F. BORDACHAR, QUILLERY - P. BOUTIGNY, CAMPENON BERNARD SGE -

L. CHANTRON, CETU - D. CUELLAR, SNCF - J.M. FREDET, SIMECSOL - J.L. GIAFFERI, EDF-GDF - J. GUILLAUME, PICO GROUPE RAZEL - P. JOVER, S.M.A.T. - CH. MOLINES, FOUGEROLLES BALLOT -

P. RENAULT, PICO GROUPE RAZEL - Y. RESCAMPS, DESQUENNE ET GIRAL

ACKNOWLEDGEMENTS ARE DUE TO THE FOLLOWING FOR CHECKING THIS DOCUMENT:M. MAREC, MISOA - M.C. MICHEL, OPPBTP - P. BARTHES, AFTES

A.F.T.E.S. will be pleased to receive any suggestions concerning these recommendations

Version 1 - 2000 -approved by the Technical Committee of 23 November 1999 Translated in 2000

INTRODUCTION

The first recommendations on mecha-nized tunnelling techniques issued in1986 essentially concerned hard -

rock machines.The shape of the French market has chan-ged a great deal since then. The deve-lopment of the hydropower sector whichwas first a pioneer, then a big user ofmechanized tunnelling methods has pea-ked and is now declining. In its place, tun-nels now concern a range of generallyurban works, i.e. sewers, metros, roadand rail tunnels.Since most of France’s large urbancentres are built on the flat, and often onrivers, the predominant tunnelling tech-nique has also switched from hard rockto loose or soft ground, often below thewater table.To meet these new requirements, France

has picked up on trends from the east(Germany and Japan).Faced with France’s extremely variedg e o l o g y, project owners, contractors,engineers, and suppliers have adaptedthese foreign techniques to their newconditions at astonishing speed.Now, this new French technical culture isbeing exported throughout the world( G e rm a n y, Egypt, United Kingdom,Australia, China, Italy, Spain, Venezuela,Denmark, Singapore, etc.).This experience forms the basis for theserecommendations, drawn up by a groupof 25 professionals representing the dif-ferent bodies involved.Before the large number of parametersand selection criteria, this group soonrealized that it was not possible to drawup an analytical method for choosing the

most appropriate mechanized tunnellingmethod, but rather that they could pro-vide a document which:

1) clarifies the different techniques, des-cribing and classifying them in differentgroups and categories,

2) analyzes the effect of the selection cri-teria (geological, project, environmentalaspects, etc.),

3) highlights the special features of eachtechnique and indicates its standardscope of application, together with thepossible accompanying measure s . I nother words, these new re c o m m e n d a-tions do not provide ready-made ans-wers, but guide the reader towards a rea-soned choice based on a combination oftechnical factors.

Beaumont machine, 1882. First attempt to drive a tunnel beneath the English Channel. IV-1

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Choosing mechanized tunnelling techniques

1.PURPOSE OF THESE RECOMMENDATIONS

2. MECHANIZED TUNNELLING TECHNIQUES2.1. Definition and limits2.2. Basic functions

2.2.1. Excavation2.2.2. Support and opposition to hydrostatic pressure2.2.3. Mucking out

2.3. Main risks and advantages of mechanized tunnellingtechniques

3. CLASSIFICATION OF MECHANIZED TUNNELLING TECH-NIQUES

4. DEFINITION OF THE DIFFERENT MECHANIZED TUNNEL-LING TECHNIQUES CLASSIFIED IN CHAPTER 34.1. Machines not providing immediate suppor t4.1.1. General

4.1.2. Boom-type tunnelling machine4.1.3. Main-beam TBM4.1.4. Tunnel reaming machine

4 . 2 . Machines providing immediate support peripherally4.2.1. General4.2.2. Open-face gripper shield TBM4.2.3. Open-face segmental shield TBM4.2.4. Double shield

4.3. Machines providing immediate peripheral and frontalsupport simultaneously

4.3.1. General4.3.2. Mechanical-support TBM4.3.3. Compressed-air TBM4.3.4. Slurry shield TBM4.3.5. Earth pressure balance machine4.3.6. Mixed-face shield TBM

5.EVALUATION OF PARAMETERS FOR CHOICE OF MECHA-NIZED TUNNELLING TECHNIQUES5.1. General5.2. Evaluation of the effect of elementary selection para-meters on the basic functions of mechanized tunnelling tech-niques5.3. Evaluation of the effect of elementary selection para-meters on mechanized tunnelling solutions

6. SPECIFIC FEATURES OF THE DIFFERENT TUNNELLINGTECHNIQUES6.1. Machines providing no immediate support

6.1.1. Specific features of boom-type tunnelling machines6.1.2. Specific features of main-beam TBMs6.1.3. Specific features of tunnel reaming machines

6.2. Specific features of machines providing immediate per-ipheral support

6.2.1. Specific features of open-face gripper shield TBMs

3

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4

4

44445666677

778899

10

1010

11

12

1212121212

12

13

1313

13131314

14

141415151515151515

15151616

16

16161616161717171818181818

181819

202124

6.2.2. Specific features of open-face segmental shieldTBMs

6.2.3. Specific features of double shield TBMs6.3. Specific features of TBMs providing immediate frontaland peripheral support

6.3.1. Specific features of mechanical-support shield TBMs6.3.2. Specific features of compressed-air TBMs6.3.3. Specific features of slurry shield TBMs6.3.4. Specific features of earth pressure balance

machines

7. APPLICATION OF MECHANIZED TUNNELLING TECH-NIQUES7.1. Machines not providing immediate support

7.1.1. Boom-type tunnelling machines7.1.2. Main-beam TBMs7.1.3. Tunnel reaming machines

7 . 2 . Machines providing immediate peripheral support7.2.1. Open-face gripper shield TBMs7.2.2. Open-face segmental shield TBMs7.2.3. Open-face double shield TBMs

7.3. Machines providing immediate frontal and peripheralsupport

7.3.1. Mechanical-support shield TBMs7.3.2. Compressed-air TBMs7.3.3. Slurry shield TBMs7.3.4. Earth pressure balance machines

8. TECHNIQUES ACCOMPANYING MECHANIZED TUNNEL-LING8.1. Preliminary investigations from the surface

8.1.1. Environmental impact assessment8.1.2. Ground conditions8.1.3. Resources used

8.2. Forward probing8.3. Ground improvement8.4. Guidance8.5. Additives8.6. Data logging8.7. Tunnel lining and backgrouting

8.7.1. General8.7.2. Lining8.7.3. Backgrouting

9. HEALTH AND SAFETY9.1. Design of tunnel boring machines9.2. Use of TBMs

APPENDIX 1APPENDIX 2APPENDIX 3

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1 - PURPOSE OF THESERECOMMENDATIONSThese recommendations supersede the pre-vious version which was issued in 1986 andwhich dealt essentially with hard - rock or“main-beam” tunnel boring machines( T B M s ) .

The scope of this revised version has beenb roadened to include all (or nearly all) typesof tunnelling machines.

The recommendations are intended to serv eas a technical guide for the difficult and ofteni rreversible choice of a tunnel bor ingmachine consistent with the expected geolo-gical and hydrogeological conditions, thee n v i ronment, and the type of the tunnel pro-j e c t .

To start with, the diff e rent kinds of machinesa re classified by group, category, and type.Since all the machines share the commoncharacteristic of excavating tunnels mecha-n i c a l l y, the first criterion for classification isnaturally the machine's ability to pro v i d eimmediate support to the excavation.

This is followed by a list of the parameterswhich should be analyzed in the selectionp rocess, then by details of the extent to whichthese parameters affect mechanized tunnel-ling techniques, and finally a series of fun-damental comments on the diff e rent kinds ofm a c h i n e .

By combining these parameters, decision-makers will arrive at the optimum choice.

The principal specific features of the diff e re n tg roups and categories of techniques are thenoutlined, and the fundamental fields of appli-cation of each category are explained.

L a s t l y, accompanying techniques, which areoften common to several techniques and vitalfor proper operation of the machine, are lis-ted and detailed. It should be noted that datalogging techniques have meant re m a r k a b l ep ro g ress has been made in technical analy-sis of the problems that can be encountere d .

Since health and safety are of constantc o n c e rn in underg round works, a specialchapter is devoted to the matter.

2 - MECHANIZED TUNNEL-LING TECHNIQUES

2.1 - DEFINITION ANDL I M I T S

For the purposes of these re c o m m e n d a t i o n s ,“mechanized tunnelling techniques” (asopposed to the so-called “conventional”techniques) are all the tunnelling techniques

in which excavation is perf o rmed mechani-cally by means of teeth, picks, or discs. Therecommendations there f o re cover all (ornearly all) categories of tunnelling machines,ranging from the simplest (backhoe digger)to the most complicated (confinement-typeshield TBM).

The mechanized shaft sinking techniquesthat are sometimes derived from tunnellingtechniques are not discussed here .

For drawing up tunnelling machine supplycontracts, contractors should refer to therecommendations of AFTES WG 17,“Pratiques contractuelles dans les travauxs o u t e rrains ; contrat de fourn i t u re d’un tun-nelier” (Contract practice for underg ro u n dworks; tunnelling machine supply contract)(TOS No. 150 November/December 1998).

2.2 - BASIC FUNCTIONS

2.2.1 - Excavation

Excavation is the primary function of all theset e c h n i q u e s .

The two basic mechanized excavation tech-niques are :

• Partial-face excavation

• Full-face excavation

With partial-face excavation, the excavationequipment covers the whole sectional are aof the tunnel in a succession of sweeps acro s sthe face.

With full-face excavation, a cutterhead -generally ro t a ry - excavates the entire sec-tional area of the tunnel in a single opera-t i o n .

2.2.2 - Support and opposition tohydrostatic pressure

Tunnel support follows excavation in the hie-r a rchy of classification.

“ S u p p o rt” here means the immediate sup-p o rt provided directly by the machine (wherea p p l i c a b l e ) .

A distinction is made between the techniquesp roviding support only for the tunnel walls,roof, and invert (peripheral support) andthose which also support the tunnel face (per-ipheral and frontal support ) .

T h e re are two types of support: passive andactive. Passive or “open-face” support re a c t spassively against decompression of the sur-rounding ground. Active or “confinement-p re s s u re” support provides active support ofthe excavation.

P e rmanent support is sometimes a direct andintegral part of the mechanized tunnelling

p rocess (segmental lining for instance). Thisaspect has been examined in other AFTESrecommendations and is not discussed fur-ther here .

Recent evolution of mechanized tunnellingtechniques now enables tunnels to be drivenin unstable, permeable, and water- b e a r i n gg round without improving the ground befo-rehand. de ceux-ci.This calls for constantopposition to the hydrostatic pre s s u re andpotential water inflow. Only confinement-p re s s u re techniques meet this re q u i re m e n t .

2.2.3 - Mucking out

Mucking out of spoil from the tunnel itself isnot discussed in these re c o m m e n d a t i o n s .H o w e v e r, it should be recalled that muckingout can be substantially affected by the tun-nelling technique adopted. Inversely, theconstraints associated with mucking opera-tions or spoil treatment sometimes affect thechoice of tunnelling techniques.

The basic mucking-out techniques are :

• haulage by dump truck or similar

• haulage by train

• hydraulic conveyance system

• pumping (less fre q u e n t )

• belt conveyors

2.3 - MAIN RISKS ANDA D VA N TAGES OF MECHANIZED TUNNELLINGT E C H N I Q U E S

The advantages of mechanized tunnellinga re multiple. They are chiefly:

• enhanced health and safety conditions forthe workforce,

• industrialization of the tunnelling pro c e s s ,with ensuing reductions in costs and lead-t i m e s ,

• the possibility some techniques provide ofc rossing complex geological and hydro g e o-logical conditions safely and economically,

• the good quality of the finished pro d u c t( s u rrounding ground less altered, pre c a s tc o n c rete lining segments, etc.)

H o w e v e r, there are still risks associated withmechanized tunnelling, for the choice oftechnique is often irreversible and it is oftenimpossible to change from the technique firstapplied, or only at the cost of immenseupheaval to the design and/or the econo-mics of the pro j e c t .

Detailed analysis of the conditions underwhich the project is to be carried out shouldsubstantially reduce this risk, something for

- Choosing mechanized tunnelling techniques

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which these recommendations will be ofg reat help. The experience and technicalskills of tunnelling machine operators arealso an important factor in the reduction ofr i s k s .

3 - CLASSIFICATION OFMECHANIZED TUNNELLINGTECHNIQUESIt was felt to be vital to have an official clas-sification of mechanized tunnelling tech-niques in order to harmonize the term i n o-logy applied to the most common methods.

The following table presents this classifica-tion. The corresponding definitions are givenin Chapter 4.

The table breaks the classification down intog roups of machines (e.g. boom-type unit) onthe basis of a pre l i m i n a ry division into typesof immediate support (none, peripheral, per-ipheral and frontal) provided by the tunnel-ling technique.

To give more details on the diff e rent tech-niques, the groups are further broken down

into categories and types.

4 - DEFINITION OF THE DIF-FERENT MECHANIZED TUN-NELLING TECHNIQUESCLASSIFIED IN CHAPTER 3

4.1 - MACHINES NOT PROVIDING IMMEDIAT ES U P P O RT

4.1.1 - General

Machines not providing immediate supporta re necessarily those working in ground notrequiring immediate and continuous tunnels u p p o rt .

4.1.2 - Boom-type tunnellingmachine

Boom-type units (sometimes called “tunnelheading machines”) are machines with aselective excavation arm fitted with a tool ofsome sort. They work the face in a series of

sweeps of the arm. Consequently the facesthey excavate can be both varied andvariable. The penetration force of the tools isresisted solely by the weight of the machineLaréaction à.

This group of machines is fitted with one oft h ree types of tool:

• Backhoe, ripper, or hydraulic impact bre a-k e r

• In-line cutterhead (ro a d h e a d e r )

• Transverse cutterhead (ro a d h e a d e r )

AFTES data sheets: No. 8 – 14 (photo 4.1.2)

4.1.3 - Main-beam TBM

A main-beam TBM has a cutterhead thatexcavates the full tunnel face in a single pass.

The thrust on the cutterhead is reacted bybearing pads (or grippers) which pushradially against the rock of the tunnel wall.

The machine advances sequentially, in twop h a s e s :

• Excavation (the gripper unit is stationary )

• Regripping

CLASSIFICATION OF MECHANIZED TUNNELLING TECHNIQUES

IV-4

*For microtunnellers (diameter no greater than 1200 mm), refer to the work of the ISTT.**Machines used in pipe-jacking and pipe-ramming are included in these groups.

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Spoil is collected and removed re a rw a rds bythe machine itself.

This type of TBM does not play an active ro l ein immediate tunnel support .

AFTES data sheets: No. 1 to 7, 10 to 13, 15to 24, 26 to 30, 67(photo 4.1.3)

➀ Transverse cutterhead

Boom➁Muck conveyor➂

Loading apron

Crawler chassis

➃➄

Phot o 4 .1 .2 - RoadheaderSchéma 4.1 .2

➀➁

➃ ➄

Phot o 4.1 .4 - Sauges t unnel (Swit zerland)

- Choosing mechanized tunnelling techniques

IV-5

4.1.4 - Tunnel reaming machine

A tunnel reaming machine has the same basic functions asa main-beam TBM. It bores the final section from an axialtunnel (pilot bore) from which it pulls itself forw a rd bymeans of a gripper unit.

➀ Pilot bore

gripper unit (traction)➁

Cutterhead➂Rear support

Muck conveyor➃➃➄

Phot o 4 .1 .3 - Lesot ho Highlands Wat er Project

➀ ➁➂ ➃

➀ Canopy/Hood/Roof

Rear gripper➁Front gripper➂Muck conveyor

Rear lift leg➃➄

➀➂

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4.2 - MACHINES PROVI -DING IMMEDIATE PERIPHE -R A L S U P P O RT

4.2.1 - General

Machines providing immediate peripherals u p p o rt only belong to the open-face TBMg ro u p .

While they excavate they also support the

sides of the tunnel. The tunnel face is not sup-p o rted. d’aucune façon.

They can have two types of shield:

• one-can shield,

• shield of two or more cans connected bya rt i c u l a t i o n s .

The diff e rent configurations for peripheral-s u p p o rt TBMs are detailed below.

4.2.2 - Open-face gripper shieldTBM

A gripper shield TBM corresponds to the defi-nition given in § 4.1.32 except that it ismounted inside a cylindrical shield incorpo-rating grippers.

The shield provides immediate passive per-ipheral support to the tunnel walls.

AFTES data sheet: N° 25

IV-6

Phot o 4 .2.2 - Main CERN t unnel

➀ Cutterhead

Muck extraction conveyor➁ ➅ Muck transfer conveyor

Motor➆Segment erector➇

Télescopic section➂Thrust ram

Grippers (radial thrust)

4.2.3 - Open-face segmentalshield TBM

An open-face segmental shield TBM is fittedwith either a full-face cutterhead or an exca-vator arm like those of the diff e rent boom-

type units. To advance and tunnel, the TBM'slongitudinal thrust rams react against thetunnel lining erected behind it by a speciale rector incorporated into the TBM.

AFTES data sheets: No. 31 - 32 - 41 - 66

a Cutterhead

Shieldb

f Muck extraction conveyor

Muck transfer conveyorgGathering armh

ij Motor

Tailskin articulation (option)kThrust ringl

Muck hopperArticulation (option)cThrust ram

Segment erector

de

Phot o 4 .2 .3Athens met ro

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4.2.4 - Double shield

A double shield is a TBM with a full-face cut-t e rhead and two sets of thrust rams that re a c tagainst either the tunnel walls (radial grip-pers) or the tunnel lining. The thrust method

used at any time depends on the type ofg round encountered. With longitudinalt h rust, segmental lining must be installedbehind the machine as it advances.

The TBM has three or more cans connected

by articulations and a telescopic central unitwhich relays thrust from the gripping/thru s-ting system used at the time to the front of theT B M .

AFTES data sheets: No. 65 – 68 – 71

- Choosing mechanized tunnelling techniques

IV-7

a Cutterheadb Front canc Telescopic sectiond Gripper unite Tailskinf Main thrust rams

g Longitudinal thrust ramsh Grippersi Tailskin articulation (option)j Segment erectork Muck extraction conveyorl Muck transfer conveyor

Phot o 4 .2 .4 - Salazie wat er t ransfer project(Reunion Island)

4.3 - MACHINES PROVI -D I N G I M M E D I ATE PERIPHE -RAL AND FRONTAL SUP -P O RT SIMULTA N E O U S LY

4.3.1 - General

The TBMs that provide immediate peripheraland frontal support simultaneously belong tothe closed-faced gro u p .

They excavate and support both the tunnelwalls and the face at the same time.

Except for mechanical-support TBMs, they all

have what is called a cutterhead chamber atthe front, isolated from the re a rw a rd part ofthe machine by a bulkhead, in which a confi-nement pre s s u re is maintained in order toactively support the excavation and/orbalance the hydrostatic pre s s u re of theg ro u n d w a t e r.

The face is excavated by a cutterhead wor-king in the chamber.

The TBM is jacked forw a rd by rams pushingo ff the segmental lining erected inside theTBM tailskin, using an erector integrated intothe machine.

4.3.2 - Mechanical-support TBM

A mechanical-support TBM has a full-facec u t t e rhead which provides face support byconstantly pushing the excavated materialahead of the cutterhead against the sur-rounding gro u n d .

Muck is extracted by means of openings onthe cutterhead fitted with adjustable gatesthat are controlled in real time.

AFTES data sheets: No. 38 – 39 – 40 – 51 –58 – 64

a Cutterheadb Shieldc Articulation (option)d Thrust rame Segment erectorf Muck extraction conveyor

g Muck transfer conveyorh Muck hopper (with optional gate)i Cutterhead drive motorj Gated cutterhead openingsk Peripheral seal between cutterhead and shieldl Tailskin articulation (option)

Phot o 4.3 .2 RER Line D (Pa ris)

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4.3.3 - Compressed-air TBM

A compressed-air TBM can have either a full-face cutterhead or excavating arms like thoseof t he d i f f e r en t boom-type uni t s .Confinement is achieved by pressurizing theair in the cutting chamber.

Muck is extracted continuously or interm i t-tently by a pre s s u re - relief discharge systemthat takes the material from the confinementp re s s u re to the ambient pre s s u re in the tun-n e l .

AFTES data sheets: No. 37 – 42 – 43 – 53 –54 – 70

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a Excavating armb Shieldc Cutting chamberd Airtight bulkheade Thrust ramf Articulation (option)

g Tailskin sealh Airlock to cutting chamberi Segment erectorj Screw conveyor (or conveyor and gate)k Muck transfer conveyor Phot o 4 .3.3 - Compressed air TBM - Boom type

4.3.4 - Slurry shield TBM

A slurry shield TBM has a full-face cutte-rhead. Confinement is achieved by pre s s u r i-zing boring fluid inside the cutterhead cham-b e r. Circulation of the fluid in the chamberflushes out the muck, with a regular pre s s u rebeing maintained by directly or indire c t l yc o n t rolling discharge rates.

AFTES data sheets:No. 33 – 34 – 35 – 36 –44 – 50 – 52 – 56 – 57 -60 – 62 – 63 – 69 – 76 –C a i ro – Sydney

a Cutterheadb Shieldc Air bubbled Watertight bulkheade Airlock to cutterhead chamber

f Tailskin articulation (option)

g Thrust ramh Segment erectori Tailskin seal

j Cutterhead chamberk Agitator (option)l Slurry supply line

m Slurry return linePhoto 4 .3 .4 - Cairo met ro

a b c d e f g

h i j ke

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4.3.5 - Earth pressure balancemachine

An earth pre s s u re balance machine (EPBM)has a full-face cutterhead. Confinement isachieved by pressurizing the excavatedmaterial in the cutterhead chamber. Muck isextracted from the chamber continuously or

i n t e rmittently by a pre s s u re - relief discharg esystem that takes it from the confinementp re s s u re to the ambient pre s s u re in the tun-n e l .

EPBMs can also operate in open mode orwith compressed-air confinement if speciallye q u i p p e d .

AFTES data sheets: No. 45 – 46 - 47 – 48 –49 – 55 – 59 – 61 – 72 – 73 – 74* - 77 to8 5

*TBMs also working with compre s s e d - a i rc o n f i n e m e n t

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a Cutterheadb Shieldc Cutterhead chamberd Airtighte Thrust ram

f Articulation (option)g Tailskin sealh Airlock to cutterheau chamberi Segment erector

j Screw conveyork Muck transfer conveyor

Phot o 4.3 .5 - CaluireTunnel, Lyons (France)

4.3.6 - Mixed-face shield TBM

Mixed-face shield TBMs have full-face cutte-rheads and can work in closed or open modeand with diff e rent confinement techniques.

Changeover from one work mode to anotherre q u i res mechanical intervention to changethe machine configuration.

D i ff e rent means of muck extraction are usedfor each work mode.

T h e re are three main categories of machine:

• Machines capable of working in open

mode, with a belt conveyor extracting themuck, and, after a change in configuration,in closed mode, with earth pre s s u re balanceconfinement provided by a screw conveyor;

• Machines capable of working in openmode, with a belt conveyor extracting themuck, and, after a change in configuration,in closed mode, with slurry confinement pro-vided by means of a hydraulic mucking outsystem (after isolation of the belt conveyor);

• Machines capable of providing earth pre s-s u re balance and slurry confinement.

TBMs of this type are generally restricted tol a rge-diameter bores because of the spacere q u i red for the special equipment re q u i re dfor each confinement method.

AFTES data sheets: A86 Ouest (Socatop),Madrid metro packages 2 & 4, KCR 320(Hong Kong)

Phot o 4.3 .6b - A86 Ouest t unnel (Socat op) Madrid met ro

Phot o 4 .3.6aA86 Oues t unnel (Socat op)

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5 - EVALUATION OF PARA-METERS FOR CHOICE OFMECHANIZED TUNNELLINGTECHNIQUES

5 . 1 .G E N E R A L

It was felt useful to assess the degree to whiche l e m e n t a ry parameters of all kinds affect thedecision-making process for choosing bet-ween the diff e rent mechanized tunnellingt e c h n i q u e s .

The objectives of this evaluation are :

• to rank the importance of the elementaryselection parameters, with some indicationof the basic functions concern e d .

• to enable project designers envisaging amechanized tunnelling solution to check thatall the factors affecting the choice have beene x a m i n e d .

• to enable contractors taking on constru c-tion of a project for which mechanized tun-nelling is envisaged to check that they are inpossession of all the relevant information ino rder to validate the solution chosen.

This evaluation is presented in the form of twotables (Tables 1 and 2).

Table 1 (§ 5.2.) indicates the degree to whicheach of the elementary selection parametersa ffects each of the basic functions of mecha-nized tunnelling techniques (all techniquesc o m b i n e d ) .

Table 2 (§ 5.3) indicates the degree to which

each of the elementary selection parametersa ffects each individual mechanized tunnel-ling technique.

These evaluation tables are complementedby comments in the appendix.

The list of parameters is based on that drawnup by AFTES recommendations work gro u pNo. 7 in its very useful document "Choix desp a r a m è t res et essais géotechniques utiles àla conception, au dimensionnement et àl'exécution des ouvrages creusés en souter-rain" (Choice of geotechnical parametersand tests of relevance to the design andc o n s t ruction of underg round works). This ini-tial list has been complemented by factorsother than geotechnical ones.

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Basic funct ion SUPPORT OPPOSITION TOEXCAVATION

MUCKING OUT,Element ary

Front al PeriphericalHYDROSTATIC EXTRACTION,

paramet ers PRESSURE TRANSPORTSTOCKPILING

A B C D E

1. NATURAL CONTRAINTS 2 2 SO 1 0

2. PHYSICAL PARAMETERS 2.1 Ident ificat ion 2 1 2 2 12.2 Global appreciat ion of qualit y 2 2 0 1 02.3 Discont inuit ies 2 2 2 1 02.4 Alt erabilit y 1 1 SO 1 12.5 Wat er chemist ry 1 0 SO 0 1

3. MECHANICAL PARAMETERS3.1 St rengt h Soft ground 2 2 SO 1 0

Hard rock 1 1 SO 2 03.2 Deformabilit y 2 2 SO 0 03.3 Liquefact ion pot ent ial 0 0 0 0 0

4. HYDROGEOLOGICAL PARAMETERS 2 2 2 1 0

5. OTHER PARAMETERS5.1 Abrasiveness - Hardness 0 0 0 2 15.2 Propensit y t o st ick 0 0 0 2 25.3 Ground/ machine f rict ion 0 1 0 0 05.4 Présence of gas 0 0 0 0 0

6. PROJECT CHARACTERISTICS6.1 Dimensions, shape 2 2 2 1 26.2 Vert ical alignment 0 0 0 0 26.3 Horizont al alignment 0 0 0 0 16.4 Environment

6.4.1 Sensit ivit y t o set t lement 2 2 2 0 06.4.2 Sensit ivit y to disturbance and work const raint s 0 0 0 0 2

6.5 Anomalies in ground6.5.1 Het erogeneit y of ground in t unnel sect ion 1 1 0 2 06.5.2 Nat ural/ art if icial obst acles 0 0 0 1 06.5.3 Voids 2 2 2 0 0

2 : Decisiv e 1 : Has ef f ect 0 : No ef f ect SO: Not appl icable

See comment s on t his t able in Appendix 1

5.2 - EVALUATION OF THE EFFECT OF ELEMENTARY SELECTION PARAMETERS ON THEBASIC FUNCTIONS OF MECHANIZED TUNNELLING TECHNIQUES

Table 1

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6 - SPECIFIC FEATURES OFTHE DIFFERENT TUNNEL-LING TECHNIQUES

6.1 - MACHINES PROVI -DING NO IMMEDIATE SUP -P O RT

6.1.1 - Specific features of boom-type tunnelling machines

a) GeneralBoom-type tunnelling machines are gene-rally suited to highly cohesive soils and softrock. They consist of an excavating arm orboom mounted on a self-propelling chassis.T h e re is no direct relationship between themachine and the shape of the tunnel to bedriven; the tunnel cross-sections excavatedcan be varied and variable. The face can beaccessed directly at all times. Since thesemachines react directly against the tunnelf l o o r, the floor must have a certain bearingc a p a c i t y.

b) ExcavationThe arms or booms of these machines aregenerally fitted with a cutting or milling headwhich excavates the face in a series ofsweeps. These machines are called ro a d-headers. The maximum thrust on the ro a d-header cutterhead is directly related to themass of the machine. The cutters work eithertransversally (perpendicular to the boom) orin-line (axially, about the boom axis). In mostcases the spoil falling from the face is gathe-red by a loading apron fitted to the front ofthe machine and transported to the back ofthe machine by belt conveyor. This excava-tion method generates a lot of dust which hasto be controlled (extraction, water spray, fil-tering, etc.).

In some cases the cutterhead can be re p l a-ced by a backhoe bucket, ripper, or hydrau-lic impact bre a k e r.

c) Support and opposition to hydro s t a -tic pre s s u reT h e re is no tunnel support associated withthis type of machine. It must be accompaniedby a support method consistent with theshape of the tunnel and the ground condi-tions encountered (steel ribs, rockbolts, shot-c rete, etc.).

This type of machine cannot oppose hydro-static pre s s u re, so accompanying measure s( g round improvement, groundwater lowe-ring, etc.) may be necessary.

d) Mucking outMucking out can be associated with this kind

of machine or handled separately. It can bedone directly from the face.

6.1.2 - Specific features of main-beam TBMs

a) GeneralThe thrust at the cutterhead is reacted to oneor two rows of radial thrust pads or gripperswhich take purchase directly on the tunnelwalls. As with shield TBMs, a trailing backupbehind the machine carries all the equipmentit needs to operate and the associated logis-tics. Forw a rd probe drilling equipment isgenerally fitted to this type of TBM. The facecan be accessed by retracting the cutterh e a df rom the face when the TBM is stopped.

The machine advances sequentially (bore ,regrip, bore again).

b) ExcavationThese full-face TBMs generally have a ro t a ryc u t t e rhead dressed with diff e rent cutters (disccutters, drag bits, etc.). Muck is generallyremoved by a series of scrapers and a buc-ket chain which delivers it onto a conveyort r a n s f e rring it to the back of the machine.Water spray is generally re q u i red at the faceboth to keep dust down and to limit the tem-p e r a t u re rise of the cutters.

c) Support and opposition to hydro s t a -tic pre s s u reTunnel support is independent of the machine(steel ribs, rockbolts, shotcrete, etc.) but canbe erected by auxiliary equipment mountedon the beam and/or backup. If support ise rected from the main beam, it must takeaccount of TBM movement and the gripperadvance stroke. The cutterhead is not gene-rally designed to hold up the face. A canopyor full can is sometimes provided to pro t e c toperators from falling blocks.

This kind of TBM cannot oppose hydro s t a t i cp re s s u re . Accompanying measu re s( g roundwater lowering, drainage, gro u n di m p rovement, etc.) are re q u i red if the expec-ted pre s s u res or inflows are high.

d) Mucking out Mucking out is generally done with wagonsor by belt conveyor. It is directly linked to theTBM advance cycle.

6 . 1 . 3 . Specific features of tunnelreaming machines

a) GeneralTunnel reaming machines work in much thesame way as main-beam TBMs, except thatthe cutterhead is pulled rather than pushed.This is done by a traction unit with grippersin a pilot bore. As with all main-beam andshield machines, the cutterhead is rotated by

a series of hydraulic or electric motors. Thetunnel can be reamed in a single pass with asingle cutterhead or in several passes withc u t t e rheads of increasing diameter.

b) ExcavationSee Chapter 6.1.2 § b) (main-beam TBM).

c) Support and opposition to hydro s t atic pre s s u re The support in the pilot bore must be des-t ructible (glass-fibre rockbolts) or re m o v a b l e(steel ribs) so that the cutterhead is not dama-ged. The final support is independent of thereaming machine, but can be erected fro mits backup.

For details on opposition to the hydro s t a t i cp re s s u re, see Chapter 6.1.2 § c (main-beamT B M ) .

d) Mucking outSee Chapter 6.1.2.§ d) (main-beam TBM).

6.2 - SPECIFIC FEATURES OFMACHINES PROVIDINGI M M E D I ATE PERIPHERALS U P P O RT

6.2.1 - Specific features of open-face gripper shield TBMs

a) GeneralAn open-face gripper shield TBM is the sameas a main-beam TBM except that it has acylindrical shield.

The thrust of the cutterhead is reacted againstthe tunnel walls by means of radial pads (orgrippers) taking purchase through openingsin the shield or immediately behind it. As withother TBM types, a backup trailing behindthe TBM carries all the equipment it needs tooperate, together with the associated logis-tics.

The TBM does not thrust against the tunnellining or support .

b) ExcavationSee Chapter 6.1.2 § b) (main-beam TBM).

c) Support and opposition to hydro s t atic pre s s u reThe TBM provides immediate passive per-ipheral support. It also protects workers fro mthe risk of falling blocks. If permanent tunnels u p p o rt is re q u i red, it consists either of seg-ments (installed by an erector on the TBM) orof support erected independently.

This type of machine cannot oppose hydro-static pre s s u re, so accompanying measure s( g round improvement, groundwater lowe-ring, etc.) may be necessary when workingin water-bearing or unstable terr a i n .

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d) Mucking outSee Chapter 6.1.2 § d) (main-beam TBM) .

6.2.2 - Specific features of open-face segmental shield TBMs

a) GeneralAn open-face shield segmental TBM haseither a full-face cutterhead or an excavatinga rm like those of the diff e rent boom-type tun-nelling machines. The TBM is thrust forw a rdby rams reacting longitudinally against thetunnel lining erected behind it.

b) ExcavationTBM advance is generally sequential:

1) boring under thrust from longitudinalrams reacting against the tunnel lining

2) retraction of thrust rams and erection ofnew ring of lining.

c) Support and opposition to hydro s t a -tic pre s s u reThe TBM provides passive peripheral sup-p o rt and also protects workers from the riskof falling blocks.

The tunnel face must be self-supporting. Evena full-face cutterhead can only hold up theface under exceptional conditions (e.g. limi-tation of collapse when the TBM is stopped).

Te m p o r a ry or final lining is erected behindthe TBM by an erector mounted on it. It isagainst this lining that the rams thrust to pushthe machine forw a rd.

This type of machine cannot oppose hydro-static pre s s u re, so accompanying measure s( g round improvement, groundwater lowe-ring, etc.) may be necessary when workingin water-bearing or unstable terr a i n .

d) Mucking outMuck is generally removed by mine cars orbelt conveyors. Mucking out is directly linkedto the TBM advance cycle.

6.2.3 - Specific features of doubleshield TBMs

Double shield TBMs combine radial pur-chase by means of grippers with longitudi-nal purchase by means of thrust rams re a c-ting against the lining. A telescopic sectionat the centre of the TBM makes it possible forexcavation to continue while lining segmentsa re being erected.

Excavation proceeds as follows: with the re a rsection of the TBM secured by the grippers,the front section thrusts against it by meansof the main rams between the two sections,and tunnels forw a rd. A ring of segmentallining segments is erected at the same time.The grippers are then released and the lon-

gitudinal rams thrust against the tunnel liningto shove the rear section forw a rd. The re a rsection regrips and the cycle is repeated.

6.3 - SPECIFIC FEATURES OFTBMS PROVIDING IMME -D I ATE FRONTAL AND PER -IPHERAL SUPPORT

6.3.1 - Specific features of mecha-nical-support shield TBMs

a) GeneralM e c h a n i c a l - s u p p o rt shield TBMs ensure thestability of the excavation by retaining exca-vated material ahead of the cutterhead. Thisis done by partially closing gates on ope-nings in the head.

b) ExcavationThe face is excavated by a full-face cutte-rh e a d .

c) Support and opposition to hydro s t a -tic pre s s u reReal-time adjustment of the openings in thec u t t e rhead holds spoil against the face.

F rontal support is achieved by holding spoilagainst the face (in front of the cutterh e a d ) .

The shield provides immediate passive per-ipheral support .

The tunnel lining is ere c t e d :• either inside the TBM tailskin, in which caseit is sealed against the tailskin (tail seal) andback grout is injected into the annular spacea round it,• or behind the TBM tailskin (expandedlining, segments with pea-gravel backfill andg rout).

This type of machine cannot oppose hydro-static pre s s u re as a rule, so accompanyingm e a s u res (ground improvement, gro u n d w a-ter lowering, etc.) may be necessary whenworking in water-bearing or unstable ter-r a i n .

d) Mucking outMucking out is generally by means of minecars or belt conveyors.

6.3.2 - Specific features of com-pressed-air TBMs

a) GeneralWith compressed-air TBMs, only pre s s u r i-zation of the air in the cutter chamberopposes the hydrostatic pre s s u re at the face.

C o m p ressed-air confinement pre s s u re ispractically uniform over the full height of theface. On the other hand, the pre s s u re dia-

gram for thrust due to water and ground atthe face is trapezoidal. This means there ared i ff e rences in the balancing of pre s s u res atthe face. The solution generally adoptedinvolves compressing the air to balance thewater pre s s u re at the lowest point of the face.The greater the diameter, the greater theresulting pre s s u re diff e rential; for this re a s o nthe use of compressed-air confinement inl a rge-diameter tunnels must be studied verya t t e n t i v e l y.

C o m p ressed-air TBMs are generally usedwith moderate hydrostatic pre s s u res (lessthan 0.1 MPa).

b) ExcavationThe face can be excavated by a variety ofequipment (from diggers to full-face cutte-rheads dressed with an array of tools). In thecase of rotating cutterheads, the size of thespoil discharged is controlled by the ope-nings in the cutterheadla ro u e .

Muck can be extracted from the face by as c rew conveyor (low hydrostatic pre s s u re) orby an enclosed conveyor with an airlock.

c) Support and opposition to hydro s t a -tic pre s s u reMechanical immediate support of the tunnelface and walls excavation is provided by thec u t t e rhead and shield re s p e c t i v e l y.

The hydrostatic pre s s u re in the ground isopposed by compressed air.

d) Mucking outMuck is generally removed by conveyor orby wheeled vehicles (trains, trucks, etc.).

6.3.3 - Specific features of slurryshield TBMs

a) GeneralThe principle of slurry shield TBM operationis that the tunnel excavation is held up bymeans of a pressurized slurry in the cutte-rhead. The slurry entrains spoil which isremoved through the slurry re t u rn line.

The tunnel lining is erected inside the TBMtailskin where a special seal (tailskin seal)p revents leakage.

Back grout is injected behind the lining as theTBM advances.

b) ExcavationThe face is excavated by a full-face cutte-rhead dressed with an array of cutter tools.Openings in the cutterhead (plus possibly ac rusher upline of the first slurry re t u rn linesuction pump) control the size of spoil re m o-ved before it reaches the pumps.

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c) Support and opposition to hydro s t a -tic pre s s u reF rontal and peripheral support of the tunnelexcavation are the same, i.e. by means of thes l u rry pre s s u re generated by the hydraulicmucking out system.

In permeable ground (K ≥ 5 x 10-5 m/s) it ispossible to pressurize the chamber by cre a-ting a ‘cake’ of thixotropic slurry (bentonite,p o l y m e r, etc.), generally with relative densityof between 1.05 and 1.15, on a tunnel faceand walls.

With such a ‘cake’ in place it is possible forworkers to enter the pressurized cutterh e a d(via an airlock).

The TBM can be converted to open mode, butthe task is complex.

As for tunnel support, the hydrostatic pre s-s u re is withstood by forming a ‘cake’ to helpf o rm a hydraulic gradient between theh y d rostatic pre s s u re in the ground and thes l u rry pre s s u re in the cutterhead chamber.

Together with control of the stability of theexcavation and of settlement, opposition toh y d rostatic pre s s u re is a design considera-tion for the confinement pre s s u re; the confi-nement pre s s u re is regulated either by dire c tadjustment of the slurry supply and re t u rnpumps or by means of an “air bubble” whoselevel and pre s s u re are controlled by a com-p ressor and relief valves. With an “airbubble” in the cutterhead chamber the confi-nement pre s s u re can be measured and re g u-lated within a very narrow range of varia-t i o n .

d) Mucking outMuck is removed by pumping it through thepipes connecting the TBM to the slurry sepa-ration and recycling plant.

In most cases the muck is often treated out-side the tunnel, in a slurry separation plant.This does introduce some risks associatedwith the type of spoil to be treated (cloggingof plant, difficulties for disposal of re s i d u a ls l u d g e ) .

The pump flowrate and the treatment capa-city of the separation plant determine TBMp ro g re s s .

6.3.4 - Specific features of earthpressure balance machines

a) General The principle of EPBM operation is that theexcavation is held up by pressurizing thespoil held in the cutterhead chamber tobalance the earth pre s s u re exerted. If neces-s a ry, the bulked spoil can be made moreplastic by injecting additives from the ope-nings in the cutterhead chamber, the pre s-

s u re bulkhead, and the muck-extractions c rew conveyor. By reducing friction, theadditives reduce the torque re q u i red to churnthe spoil, thus liberating more torque to workon the face. They also help maintain aconstant confinement pre s s u re at the face.

Muck is extracted by a screw conveyor, pos-sibly together with other pre s s u re - re l i e fd e v i c e s .

The tunnel lining is erected inside the TBMtailskin, with a tailskin seal ensuring there areno leaks. Back grout is injected behind thelining as the TBM advances.

b) ExcavationThe tunnel is excavated by a full-face cutte-rhead dressed with an array of tools. The sizeof spoil removed is controlled by openings inthe cutterhead which are in turn determ i n e dby the dimensional capacity of the scre wc o n v e y o r.

The power at the cutterhead has to be highbecause spoil is constantly churned in thec u t t e rhead chamber.

c) Support and opposition to hydro s t a -tic pre s s u reFace support is uniform. It is obtained bymeans of the excavated spoil and additiveswhich generally maintain its relative densityat between 1 and 2. Peripheral support canbe enhanced by injecting products thro u g hthe shield.

For manual work to proceed in the cutte-rhead chamber, it may be necessary toc reate a sealing cake at the face thro u g hc o n t rolled substitution (without loss of confi-nement pre s s u re) of the spoil in the chamberwith bentonite slurry.

L’ a rc h i t e c t u re de ce type de tunnelier perm e tun passage rapide du mode fermé en modeo u v e rt .

The hydrostatic pre s s u re is withstood by for-ming a plug of confined earth in the cham-ber and screw conveyor; the pre s s u re gra-dient between the face and the spoild i s c h a rge point is balanced by pre s s u relosses in the extraction and pre s s u re - re l i e fd e v i c e .

C a re must be take over the type and locationof sensors in order to achieve proper mea-s u rement and control of the pre s s u re in thec u t t e rhead chamber.

d) Mucking outAfter the muck-extraction screw conveyor,spoil is generally transported by conveyorsor by wheeled vehicles (trains, tru c k s ) .

The muck is generally “diggable”, enablingit to be disposed of without additional tre a t-ment; however, it may be necessary to study

the biodegradability of the additives if thedisposal site is in a sensitive enviro n m e n t .

The arc h i t e c t u re of this type of TBM allows forrapid changeover from closed to open modeand vice versa.

7 - APPLICATION OFMECHANIZED TUNNELLINGTECHNIQUES

7.1 - MACHINES NOT PRO -VIDING IMMEDIATE SUP -P O RT

7.1.1 - Boom-type tunnellingmachines

Boom-type units are generally suitable forhighly cohesive soils and soft rock. Theyreach their limits in soils with compre s s i v es t rength in excess of 30 to 40 MPa, whichc o rresponds to class R3 to R5 in the classifi-cation given in Appendix 3 (depending onthe degree of cracking or foliation). Thee ffective power of these machines is dire c t l yrelated to their weight.

When these machines are used in water-bearing ground, some form of gro u n di m p rovement must be carried out before-hand to overcome the problem of significantwater inflow.

When excavating clayey soils in water, thecutters of roadheaders may become cloggedor balled; in such terrain, a special study ofthe cutters must carried out to overcome thep roblem. It may be advisable to use a back-hoe instead.

These techniques are particularly suitable forexcavating tunnels with short lengths of dif-f e rent cross-sections, or where the tunnel isto be driven in successive headings.

The tunnel support accompanying thismethod of excavation is independent of themachine used. It will be adapted to the condi-tions encountered (ground, enviro n m e n t ,etc.) and the shape of the excavation.

7.1.2 - Main-beam TBMs

Main-beam TBMs are particularly suited totunnels of constant cross-section in rock ofs t rength classes R1 to R4 (see rock classifi-cation in Appendix 3).

For the lower strength classes (R3b-R4), thebearing surface of the grippers is generallyi n c reased in order to prevent them punchinginto the ground. If there is a risk of alterationof the tunnel floor due to water, laying ac o n c rete invert behind the machine will faci-

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litate movement of the backup. To pro v i d es h o rt - t e rm stabilization of the excavation, itwill be necessary to have rapid support - e re c-tion systems that will be independent of butn e v e rtheless compatible with the TBM.

For the higher strength classes (R1-R2a), allthe boreability parameters must be taken intoaccount in the TBM design.

In hard and abrasive ground in part i c u l a r, itis recommended that every precaution betaken to allow for cutters to be replaced inp e rfect safety.

A system for spraying water on the tunnelface will cool the cutters and keep dust down.It can be complemented by dust scre e n s ,extraction, and filters.

Main-beam TBMs are generally fitted withd e s t ructive drilling rigs for forw a rd pro b edrilling, together with drill data-loggingequipment. The probe holes are drilled whenthe TBM is not working.

The design of these machines does not allowthem to support non-cohesive soils as theyadvance, or to oppose hydrostatic pre s s u re .For this reason accompanying measure ssuch as drainage and/or consolidation ofthe ground are necessary before themachines traverse a geological accident.Consequently the TBM must be equipped todetect such features and to treat the gro u n dahead of the face when necessary.

7.1.3 - Tunnel reaming machines

Tunnel reamers are suitable for excavatingl a rge horizontal or inclined tunnels (upward sof 8 m in diameter) in rock (R1 to R3, some-times R4 and R5).

The advantages of reaming a tunnel from apilot bore are as follows:

• The ground is investigated as the pilot boreis driven

• Any low-strength ground encountered canbe consolidated from the pilot bore beforefull-diameter excavation

• The ground to be excavated is drained

• The pilot bore can be used for dewateringand ventilation

• Te m p o r a ry support can be erected inde-pendently of the machine.

7.2 - MACHINES PROVI -DING IMMEDIATE PERIPHE -RAL SUPPORT

7.2.1 - Open-face gripper shieldTBMs

Open-face gripper shield TBMs are part i c u-larly suitable for tunnelling in rock of stre n g t hclasses between R1 and R3

The shield provides immediate support forthe tunnel and/or protects the workforc ef rom falling blocks.

The shield can help get through certain geo-logical difficulties by avoiding the need fors u p p o rt immediately behind the cutterh e a d .

Application of this technique can be limitedby the ability of the ground to withstand theradial gripper thru s t .

The general considerations outlined in §7.1.2 also apply here .

7.2.2 - Open-face segmentalshield TBMs

An open-face segmental shield TBM re q u i re sfull lining or support along the length of thetunnel against which it can thrust to advance.

Its field of application is soft rock (stre n g t hclasses R4 and R5) and soft ground re q u i r i n gs u p p o rt but in which the tunnel face holds up.

The general considerations outlined in §7.1.2 also apply here .

This type of TBM can traverse certain typesof heterogeneity in the ground. It alsoenables the tunnel support to be industriali-zed to some extent. On the other hand, thep resence of the lining and shield can give riseto difficulties when crossing obstacles suchas geological accidents, since they hinderaccess to the face for treatment or consoli-dation of the gro u n d .

7.2.3 - Open-face double shieldTBMs

Open-face double shield TBMs combine theadvantages and disadvantages associatedwith radial grippers and longitudinal thru s trams pushing off tunnel lining: they needeither a lining or ground of sufficient stre n g t hto withstand gripper thru s t .

This greater technical complexity is some-times chosen when lining is re q u i red so thatboring can proceed (with gripper purc h a s e )while the lining ring is being ere c t e d .

7.3 - MACHINES PROVI -DING IMMEDIATE FRONTA LAND PERIPHERAL SUPPORT

7.3.1 - Mechanical-support shieldTBMs

The diff e rence between mechanical-supportshield TBMs and open-face segmental shieldTBMs lies in the nature of the cutterh e a d .M e c h a n i c a l - s u p p o rt TBMs have:

• openings with adjustable gates

• a peripheral seal between the cutterh e a dand the shield.

Face support is achieved by holding spoilahead of the cutterhead by adjusting theopenings. It does not provide ‘genuine’confinement, merely passive support of thef a c e .

Its specific field of application is there f o re insoft rock and consolidated soft ground withlittle or no water pre s s u re

7.3.2 - Compressed-air TBMs

C o m p ressed-air TBMs are particularly sui-table for ground of low permeability with nomajor discontinuities (i.e. no risk of suddenloss of air pre s s u re ) .

The ground tunnelled must necessarily havean impermeable layer in the overburd e n .

C o m p ressed-air TBMs tend to be used toexcavate small-diameter tunnels.

Their use is not recommended in circ u m-stances where the ground at the face is hete-rogeneous (unstable ground in the ro o fwhich could cave in). They should be pro h i-bited in organic soil where there is a risk off i re .

In the case of small-diameter tunnels, it maybe possible to have compressed air in all orp a rt of the finished tunnel.

7.3.3 - Slurry shield TBMs

S l u rry shield TBMs are particularly suitablefor use in granular soil (sand, gravel, etc.)and heterogeneous soft ground, though theycan also be used in other terrain, even if itincludes hard - rock sections.

T h e re might be clogging and difficulty sepa-rating the spoil from the slurry if there is clayin the soil.

These TBMs can be used in ground with highp e rmeability (up to 10-2 m/s), but if there ishigh water pre s s u re a special slurry has tobe used to form a watertight cake on theexcavation walls. However, their use isusually restricted to hydrostatic pre s s u res ofa few dozen MPa.

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Generally speaking, good control of slurryquality and of the regularity of confinementp re s s u re ensures that surface settlement iskept to the very minimum.

Contaminated ground (or highly aggre s s i v ewater) may cause problems and re q u i re spe-cial adaptation of the slurry mix design.

The presence of methane in the ground is nota problem for this kind of TBM.

If the tunnel alignment runs through contras-ting heterogeneous ground, there may bed i fficulties extracting and processing thes p o i l .

7.3.4 - Earth pressure balancemachines

EPBMs are particularly suitable for soilswhich, after churning, are likely to be of aconsistency capable of transmitting the pre s-s u re in the cutterhead chamber and form i n ga plug in the muck-extraction screw conveyor(clayey soil, silt, fine clayey sand, soft chalk,marl, clayey schist).

They can handle ground of quite high per-meability (10–3 to 10-4 m/s), and are alsocapable of working in ground with occasio-nal discontinuities requiring localized confi-nement.en l’absence

In hard and abrasive ground it may ben e c e s s a ry to use additives or to take specialm e a s u res such as installing hard-facing orwearplates on the cutterhead and scre wc o n v e y o r.a vitesse de pro g ression de l’usurepar

In permeable ground, maintenance in thec u t t e rhead chamber is made complexbecause of the need to establish a watert i g h tcake at the face beforehand, without losingconfinement pre s s u re .

8 - TECHNIQUES ACCOMPA-NYING MECHANIZED TUN-NELLING

8.1 - PRELIMINARY INVES -T I G ATIONS FROM THE SUR -FA C E

8.1.1 - Environmental impactassessment

At the pre l i m i n a ry design stage an enviro n-mental impact assessment should be carr i e dout in order to properly assess the dimensio-nal characteristics proposed for the tunnel,p a rticularly its cross-section, sectional are a ,and overburd e n .

In addition, the effect and sensitivity of sett-

lement-especially in built-up are a s - s h o u l dbe given special attention. This is a decisivefactor in choosing the tunnelling and supportmethods, the tunnel alignment, and thec ro s s - s e c t i o n .

The environmental impact assessment shouldbe thorough, taking account of the density ofexisting works and the diversity of their beha-v i o u r s .

For existing underg round works, the com-patibility of the proposed tunnelling and sup-p o rt methods or the adaptations re q u i re d(special treatment or accompanying mea-s u res) should be assessed through speciala n a l y s i s .

8.1.2 - Ground conditions

The purpose of pre l i m i n a ry investigations isnot just for design of the temporary and per-manent works, but also to check the feasibi-lity of the project in constructional terms, i.e.with respect to excavation, mucking out, ands h o rt- and long-term stability.

Design of the works involves determ i n i n gshape, geological cross-sections, the physi-cal and mechanical characteristics of theg round encountered by the tunnel, and theh y d rogeological context of the project as aw h o l e .

P roject feasibility is determined by the poten-tial reactions of the ground, including detailsof both the formations traversed and of thet e rrain as a whole, with respect to the loa-dings generated by the works, i.e. with re s-pect to the excavation/confinement methoda d o p t e d .

Depending on the context and the specificre q u i rements of the project, the synopsis ofinvestigation results should there f o re dealwith each of the topics detailed in the AFTESrecommendations on the choice of geotech-nical tests and parameters, irrespective of thegeological context (cf.: T.O.S No. 28, 1978,re-issued 05/93 – review in pro g ress; andT.O.S No. 123, 1994).

If the excavation/confinement method isonly chosen at the tender stage, and depen-ding on the confinement method chosen bythe Contractor, additional investigationsmay have to be carried out to validate thevarious options adopted.

8.1.3 - Resources used

Depending on the magnitude and com-plexity of the project, pre l i m i n a ry investiga-tions - traditionally based on boreholes andb o rehole tests - may be extended to “larg e -scale” observation of the behaviour of theg round by means of test adits and shafts.

Advantage can be taken of the investigation

period to proceed with tests of the tunnellingand support methods as well as any asso-ciated tre a t m e n t s .

If there are to be forw a rd probe investiga-tions, matching of the boring and investiga-tion methods should be envisaged at the pre-l i m i n a ry investigation stage.

In the event of exceptional overburden condi-tions and difficult access from the surf a c e ,d i rectional drilling investigation (miningand/or petroleum industry techniques) oflong distances (one kilometre or more) alongthe tunnel alignment may be justified, espe-cially if it is associated with geophysicalinvestigations and appropriate in situ tes-t i n g .

8.2 - FORWARD PROBING

The concept of forw a rd probing must be setagainst the risk involved. This type of inves-tigation is cumbersome and costly, for itpenalizes tunnelling pro g ress since—in thecase of full-face and shield TBMs—themachine has to be stopped during pro b i n g(with current-day technology). It should the-re f o re be used only in response to an expli-cit and absolute re q u i rement to raise anyu n c e rtainty over the conditions to be expec-ted when crossing areas where site safety,p re s e rvation of existing works, or the dura-bility of the project might be at risk.

I rrespective of the methodology selected, itmust give the specialists implementing it re a lpossibilities for avoiding difficulties byimplementing corrective action in good time.

The first condition that forw a rd probing mustmeet in order to achieve this objective is thatit give sufficiently clear and objective infor-mation about the situation ahead of the face(between 1 and 5 times the tunnel diameterahead), with a leadtime consistent with therate of tunnel pro g ress.

The second condition is that in terms of qua-lity it must be adapted to the specific re q u i-rements of the project (identification of clearvoids, of decompressed areas, faults, etc.).These criteria should be determined jointlyby the Designer, Engineer, and Contractorand should be clearly featured in specifica-tions issued to the persons carrying out theinvestigations.

During tunnelling, analysis of results is gene-rally the responsibility of the investigationsc o n t r a c t o r, but the interpretation of data, inc o rrelation with TBM advance parameters(monitoring), should in principle be the re s-ponsibility of the contractor operating theT B M .

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8.3 - GROUND IMPROVE -M E N T

Prior ground improvement is sometimesn e c e s s a ry, particularly in order to cro s s :

• singular features such as break-ins andb reakouts, including on works along theroute (shafts, stations, etc.)

• discontinuities and fault zones identifiedb e f o rehand

• p e rmeable water-bearing gro u n d .

If the problem areas are of limited extent,g round improvement will sometimes enablea less sophisticated - and there f o re less costly- tunnelling technique to be adopted.

Since ground improvement is long and costlyto carry out from the tunnel (especially whenthe alignment is below the water table), thework is generally done from the surface (inthe case of shallow overburd e n ) .

These days, however, there is a trend forTBMs to be fitted with the basic equipment(such as penetrations in the bulkhead and/orcans) enabling ground improvement to bec a rried out from the machine should water-bearing ground not compatible with the tun-nelling technique adopted be encountere du n e x p e c t e d l y. This can also be the case whenlocal conditions prohibit treatment from thes u rf a c e .

When confinement-type TBMs are used,geological and hydrogeological conditionsoften re q u i re special treatment for bre a k - i n sand breakouts. This point should not be over-looked, neither at the pre l i m i n a ry designstage (surface occupation, ground and net-work investigations, works schedule) norduring the construction phase, for this is oneof the most difficult phases of tunnelling.

Special attention should be given to the com-patibility of ground treatment with the tun-nelling process (foaming, reaction withs l u rry and additives, etc.)

The most commonly used ground impro v e-ment techniques are :

• p e rm e a t i o n - g routed plug of bentonite-cement and/or gel

• diaphragm-wall box

• total replacement of soil by bentonite-c e m e n t

• j e t - g routed plug

8.4 - GUIDANCE

Guidance of full-face TBMs is vital. The per-f o rmance of the guidance system used mustbe consistent with the type of TBM and lining,and with the purpose of the tunnel.

The development of shield TBMs incorpora-ting simultaneous erection of precast seg-mental lining has led to the design of highlysophisticated guidance systems, becausewith tunnel lining it is impossible to re m e d ydevia t ion f rom the cor rec t cour se .C o n s e q u e n t l y, the operator (or automaticoperating system) must be given re a l - t i m ei n f o rmation on the position of the face andthe tunnelling trend relative to the theore t i c a lalignment. However, when considering thec o n s t ruction tolerance it must be re m e m b e-red that the lining will not necessarily be cen-t red in the excavation, and that it may be sub-je c t t o i ts own deformat ion (o f f s e t ,ovalization, etc.). The generally acceptedtolerance is an envelope forming a circ l eabout 20 cm larger in diameter than the theo-retical diameter.

Whatever the degree of sophistication of theguidance system, it is necessary to:

• reliably transfer a traverse into the tunneland close it as soon as possible (bre a k o u tinto shaft, station, etc.)

• c a rry out regular and precise topographi-cal checks of the position of the TBM and ofthe tunnel

• know how quickly (speed and distance) theTBM can react to modifications to the trajec-t o ry it is on.

8.5 - ADDITIVES

a) General Mechanized tunnelling techniques make useof products of widely differing physical andchemical natures that can all be labelled“conditioning fluids and slurries”. Before anychemical additives are used, it should bechecked that they present no danger for thee n v i ronment (they will be mixed in with themuck and could present problems when it isdisposed of) or for the workforce (part i c u-larly during pressurized work in the cutte-rhead chamber where the temperature canbe high).

b) Wa t e rWat er w i l l be pr esent in t he gr ound inv a rying quantities, and will determine thesoil's consistency, as can be seen from diff e-rent geotechnical characterization tests orc o n c rete tests (Atterberg limits for clayeysoils and slump or Abrams cone test for gra-nular soils). It can be used alone, with clay

(bentonite), with hydrosoluble polymers, orwith surfactants to form a conditioning fluid( s l u rry or foam).

c) AirBy itself air cannot be considered to be aboring additive in the same way as water orother products; its conditioning action is verylimited. When used in pressurized TBMs - ifthe permeability of the ground does not pro-hibit it - air helps support the tunnel. As ac o m p ressible fluid, air helps damp confine-m e n t - p re s s u re variations in the techniquesusing slurry machines with “air bubbles” andEPB machines with foam. As a constituent offoam, air also helps fluidify and reduce thedensity of muck, and helps regulate the confi-nement pre s s u re in the eart h - p re s s u re -balance pro c e s s .

d) BentoniteOf the many kinds of clay, bentonite is mostc e rtainly the best-known drilling or boringmud. It has extremely high swell, due to thep resence of its specific clayey constituent,montmorillonite, which gives it very intere s-ting colloidal and sealing qualities.

In the slurry-confinement technique, therheological qualities of bentonite (thixo-t ropy) make it possible to establish a confi-nement pre s s u re in a permeable medium bysealing the walls of the excavation thro u g hp ressurized filtration of the slurry into the soil( f o rmation of a sealing cake through a com-bination of permeation and membrane), andto transport muck by pumping.

Bentonite slurry can also be used with an EPBmachine, to improve the consistency of thegranular material excavated (homogeniza-tion, plastification, lubrication, etc.).

In permeable ground, the EPB technique usesthe same principle of cake formation beforework is carried out in the pressurized cutte-rhead chamber.

e) PolymersOf the multitude of products on the market,only hydrosoluble or dispersible compoundsa re of any interest as tunnelling additives.Most of these are well known products in thedrilling industry whose rheological pro p e r-ties have been enhanced to meet the specificre q u i rements of mechanized tunnelling.

These modifications essentially concernenhanced viscosifying power in order to bet-ter homogenize coarse granular materials,and enhanced lubrifying qualities in order tolimit sticking or clogging of the cutterh e a dand mucking out system when boring in cer-tain types of soil.

Polymers may be of three types:

• natural polymers (starch, guar gum, xan-

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than gum, etc.)

• modified natural or semi-synthetic poly-mers (CMC [carboxymethylcellulose], etc.)

• synthetic polymers (polyacry l a m i d e s ,p o l y a c rylates, etc.)

f) Foams (surf a c t a n t s )Foams are two-phase systems (a gas phaseand a liquid phase containing the foamingagent) which are characterized physically bytheir expansion factor (volume occupied bythe air in the foam relative to the volume ofliquid).

Foams are easy to use. They are similar toaerated slurries, combining the advantagesof a gas (compre s s i b i l i t y, practically zerod e n s i t y, etc.) and of a slurry (fluidification,lubrication, pore filling, etc.). With EPBmachines they are used to facilitate confine-ment and sometimes excavation and muc-king out as well.

8.6 - DATA LOGGING

The acquisition and restitution of TBM ope-rating parameters is undoubtedly the biggestfactor in the technical pro g ress of mechani-zed tunnelling in the last ten years.

It makes for objective analysis of the opera-ting status and dysfunctions of the machineand its auxiliaries.

The status of the machine at any given timeis short-lived and changes rapidly. Wi t h o u tdata logging, this gave rise to varied andoften erroneous interpretations in the past.

Logging gives a “true” technical analysis thatis indispensable for smooth operation onp rojects in difficult or sensitive sites.

Data logging also provides a basis for com-puterized control of TBM operation andautomation of its functions (guidance, muc-king out, confinement pre s s u re re g u l a t i o n ,e t c . ) .

Data logging also provides an exact re c o rdof operating statuses and their durations (cf.recommendation on analysis of TBM opera-ting time and coefficients, TOS No. 148, July9 8 ) .

They also constitute operating feedback thatcan be used to optimize TBM use.

8.7 - TUNNEL LINING ANDB A C K G R O U T I N G

8.7.1 - General

In t he case of segment al TBMs, t helining and its backgrouting are inseparablef rom the operation of the machine.

Without any transition and in perf e c t l yc o n t rolled fashion, the lining and backgro u tmust balance the hydrostatic pre s s u re, sup-p o rt the excavation peripherally, and limits u rface settlement.

Because of their interfaces with the machine,they must be designed in parallel and ini n t e rdependence with the TBM.

8.7.2 - Lining

The lining behind a shield TBM generallyconsists of re i n f o rced concrete segments.Sometimes (for small-diameter tunnels) cast-i ron segments are used. More exceptionallythe lining is slipcast behind a sliding form .

R e i n f o rced concrete segments are by far themost commonly used. The other techniquesa re gradually being phased out for econo-mic or technical re a s o n s .

The segments are erected by a machineincorporated into the TBM which grips themeither mechanically or by means of suction.

The following AFTES recommendations exa-mine tunnel lining:

• Recommandations sur les re v ê t e m e n t spréfabriqués des tunnels circ u l a i res au tun-nelier (Recommendations on precast liningof bored circular tunnels), TOS No. 86

• Recommandation sur les joints d’étan-chéité entre voussoirs (Recommendations ongaskets between lining segments), TOS No.116, March/April 1993

• Recommandations “pour la conception etle dimensionnement des revêtements envoussoirs préfabriqués en béton armé instal-lé s à l ’ar r i è re d ’un tunne l i er”(Recommendations “on the design of pre c a s tre i n f o rced concrete lining segments installedbehind TBMs”) drawn up by AFTES workg roup No. 18, published in TOS No. 147,May/June 1998.

8.7.3 - Backgrouting

This section concerns only mechanized tun-nelling techniques involving segmentall i n i n g .

Experience shows the extreme importance ofc o n t rolling the grouting pre s s u re and fillingof the annular space in order to control andrestrict settlement at the surface and to secu-rely block the lining ring in position, giventhat in the short term the lining is subject toits selfweight, TBM thrust, and possibly flota-tional forc e s .

G routing should be carried out continuously,with constant control , as the machineadvances, before a gap appears behind theTBM tailskin.

In the early days backfilling consisted of

either pea gravel or fast-setting or fast-har-dening cement slurry or mortar that wasinjected intermittently through holes in thes e g m e n t s .

Since management of the grout and its har-dening between mixing and injection is av e ry complex task, there has been a constantt rend to drop cement-based products infavour of products with re t a rded set (pozzo-lanic reac t ion) and low compre s s i v es t rength. Such products are injected conti-nuously and directly into the annular spaced i rectly behind the TBM tailskin by means ofg rout pipes routed through the tailskin.

9 - HEALTH AND SAFETYMechanization of tunnelling has very sub-stantially improved the health and safetyconditions of tunnellers. However, it has alsoinduced or magnified certain specific risksthat should not be overlooked. These include:• risk of electrical fire or spread of fire tohydraulic oils• risk of electro c u t i o n• risks during or subsequent to compre s s e d -air work • risks inherent to handling of heavy part s(lining segments)• mechanical risks• risk of falls and slips (walkways, ladders,e t c . )

9.1 - DESIGN OF TUNNEL -LING MACHINES

Tunnelling machines are work items that mustcomply with the regulations of the MachineryD i rective of the European Committee forS t a n d a rdization (CEN).

These regulations are aimed primarily atdesigners—with a view to obtaining equip-ment compliant with the Directive—but alsoat users.

The standards give the minimum safety mea-s u res and re q u i rements for the specific risksassociated with the diff e rent kinds of tunnel-ling machines. Primarily they apply tomachines manufactured after the date ofa p p roval of the European standard .• At the time of writing only one standardhad been homologated:- NF EN 815 “Safety of unshielded tunnelboring machines and rodless shaft boringmachines for rock” (December 1996)• T h ree are in the approval pro c e s s :- Pr EN 12111 “Tunnelling machines -Roadheaders, continuous miners and impact

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rippers – Safety re q u i re m e n t s ”- Pr EN 12336 “Tunnelling machines –Shield machines, horizontal thrust boringmachines, lining erection equipment - Safetyre q u i rements ”- Pr EN 12110 “Tunnelling machines –Airlocks – Safety re q u i rements ”

9.2 - USE OF TUNNELLINGM A C H I N E S

Machine excavation of underg round worksinvolves specific risks linked essentially toatmospheric pollution (gas, toxic gases,noise, temperature), flammable gases andother flammable products in the gro u n d ,electrical equipment (low and high voltage),hydraulic equipment (power or contro ldevices), and compressed-air work (work inl a rge-diameter cutterhead chambers underc o m p ressed air, pressurization of whole sec-tions of small-diameter tunnels).

A variety of bodies dealing with safety onpublic works projects have drawn up textsand recommendations on safety. In France,these include OPPBTP, CRAM, and INRS, fore x a m p l e .

All their re q u i rements should be incorpora-ted into the General Co-Ordination Plan andHealth and Safety Plan at the start of works.

APPENDICES 1, 2, 3, AND 41 . Comments on Table No. 1 in Chapter 52 . Comments on Table No. 2 in Chapter 53 . G round classification table4 . Mechanized tunnelling project datas h e e t s

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APPENDIX 1

COMMENTS ON TABLE NO.1 IN CHAPTER 5.

1 - Natural constraints

S u p p o rt (columns A and B)With knowledge of natural constraints:• a choice can be made f r om among t het unnel l i ng t echni que gr oups ( f r omboom- t y pe uni t s t o conf inement - t y peTBMs)

• r elax at ion of st r esses can be mana-ged ( f r om s i m pl e def or m at i on-conv er gence t o f ai lur e) .

2 - PHYSICAL PARAMETERS

2.1 - Identification

❑ Face suppor t (column A )

Wi t h know ledge of phy sical par ame-t er s:

• t he suppor t met hod can be assessed,and t he t unnel l i ng t echnique gr oupchosen

• t he r equi r ement f or f ace suppor tcan be assessed.

❑ Per ipher al suppor t (column B)

Wi t h know ledge of phy sical par ame-t er s t he r equi r ement f or per ipher alsuppor t ar ound t he machine can beassessed.

❑ Opposi t ion t o hy dr ost at ic pr essur e(column C)

Wi t h know ledge of phy sical par ame-t er s and of gr ain and block sizes, t heper meabi l i t y of t he t er r ai n can beassessed, leading t o a pr oposal f or t hew ay hy dr ost at i c pr essur e could becont r ol led.

❑ Ex cav at ion (column D)

Of t he par amet er s concer ned, gr ainand block size ar e decisiv e f or asses-sing t he ex cav at ion met hod (design ofcut t er head, cut t er s, et c.) .

2 . 2 - Global appre c i a t i o nof quality

❑ Suppor t (columns A and B)

Global appr eci at i on of qual i t y pr o-v ides addi t ional inf or mat ion f or iden-t i f i cat i on t hat concer ns onl y t hesample. This dat a def ines mor e globalinf or mat ion at t he scale of t he soi lhor izon concer ned.

2.3 - Discontinuities

❑ Suppor t (columns A and B)

This dat a concer ns r ock and coher entsof t gr ound. Wi t h know ledge of dis-cont i nui t i es a choi ce can be madeamong t he t unnel t echnique gr oups( f r om boom- t y pe uni t s t o conf ine-ment - t y pe TBMs).

❑ Opposi t ion t o hy dr ost at ic pr essur e(column C)

Wi t h know ledge of discont inui t ies t hecr ack per meabi l i t y and w at er pr es-sur e t o be t aken int o account f or t hepr oj ect can be assessed. This enablest he t y pe of t echnique t o be chosen.

❑ Ex cav at ion (column D)

In conj unct ion w i t h know ledge of blocksi zes, know ledge of di scont i nui t ies(nat ur e, size, and f r equency ) can bedecisiv e or mer ely hav e an ef f ect ont he ex cav at ion met hod t o be adopt ed.

3 - MECHANICAL PARAME-TERS

3.1 - Stre n g t h

❑ Suppor t (columns A and B)

Wi t h know ledge of mechani cal par a-met er s a pr el iminar y choice can bemade f r om among t he t unnel l ing t ech-nique gr oups ( f r om boom- t y pe uni t st o conf inement - t y pe TBMs).

❑ Ex cav at ion (har d r ock)(column D)

Know ledge of mechani cal par amet er sis par t icular ly impor t ant f or def ining

t he ar chi t ect ur e of t he machine andhelps det er mine i t s t echnical char ac-t er ist i cs ( t or que, pow er , et c.) andt he choice of cut t ing t ools.

3 . 2 - Deform a b i l i t y

❑ Suppor t (columns A and B)

Wi t h know ledge of def or mabi l i t y t her elax at ion of st r esses can be asses-sed and t aken i nt o account ( f r omsimple def or mat ion or conv er gence t of ai lur e) .

3 . 3 - Liquefaction potential

❑ Suppor t and mucking out (columnsA, B and E)

Know ledge of t he l iquef act ion pot en-t ial has an ef f ect in sei smic zones andin cases w her e t he t echnique chosenmight set up v ibr at i ons in t he gr ound(blast i ng, et c.) .

4 - HYDROGEOLOGICALPARAMETERS❑ Suppor t , opposi t ion t o hy dr ost at icpr essur e, and ex cav at i on (ColumnsA, B, C and D)

Know ledge of t hese par amet er s i sdecisiv e in appr eciat i ng cont r ol of t hest abi l i t y of t he t unnel , bot h at t he f aceand per i pher al l y , and t her ef or e i nchoosing t he met hod f r om t he v ar ioust unnel l ing t echniques. In t he case oft unnels beneat h deep ov er bur den i t isnot easy t o obt ain t hese par amet er s.They should be est imat ed w i t h t hegr eat est car e and analy zed w i t h cau-t ion.

5 - OTHER PARAMETERS❑ Ex c av a t i on and m uc k i ng ou t(Columns D and E)

The par amet er s of abr asiv eness andhar dness ar e deci si v e or hav e anef f ect in appr eciat ion of t he ex cav a-t ion and mucking- out met hods t o beused. These par amet er s should be

Page 115: Recommendations ITA TBM

Comments on Table No. 1 inChapter 5

1 - NATURAL CONSTRAINTSThe st r ess pat t er n in t he gr ound is ver yimpor t ant in deep t unnels or in cases ofhigh anisot r opy . If t he r ate of st r essr elease is high, w it h main- beam TBMs,shield TBMs, and r eaming machines, itmay cause:

• j amming of the machine (j amming oft he cut ter head or body)

• r ockbur st at t he f ace or in t unnel walls,r oof , or inver t .

Wit h slur r y - shield TBMs or EPBMs it isr ar e for t he natur al st r ess pat ter n t o bedecisive in t he choice of machine t ypesince t hey ar e gener ally used f or shal-low t unnels.

2 - PHYSICAL PA R A M E T E R S

2.1 - Identification

The t ype of gr ound plays a decisive r olein t he choice and design of a shield TBM.Consequent ly the par ameter s char acte-r izing t he ident if icat ion of t he gr oundmust be examined car efully when choo-sing t he excavat ion/ suppor t method.

The most impor t ant of t he ident if icat ionpar ameter s ar e plast icity and - f orhar dness, clogging potent ial, and abr a-siveness - miner alogy which ar e par -t icular ly decisive in t he select ion ofshield TBM component s.

Chemical analysis of t he soil can be deci-siv e in t he case of conf inement - t ypeshield TBMs because of t he ef f ect soilmight have on t he addit ives used in t hesetechniques.

2.2 - Global appreciation ofq u a l i t y

Global appr eciat ion of quali t y r esult sf r om combining par ameter s which ar eeasy t o measur e in t he labor ator y or insi t u (bor ehole logs, RQD) and v isualappr oaches.

Weat her ed zones and zones w i t hcont r ast ing har dness can cause specif icdif f icult ies f or t he dif f er ent t unnell ingtechniques, e.g. f ace instabil i ty , insuf f i-

cient st r ength f or gr ipper s, conf inementdif f icult ies.

The degr ee of weather ing of r ock has anef f ect but is not gener ally decisive forslur r y shields and EPBMs. In all cases ithas an ef f ect f or cut t er head design.

2.3 - Discontinuities

For r ock, know ledge of t he si t uat ionr egar ding discont inui t ies is decisiv e(or ientat ion and densit y of t he networ k),f or it w ill af f ect t he choice of t he tun-nell ing and suppor t t echnique as well asthe tunnell ing speed.

Wi th open- f ace main- beam TBMs andshields and mechanical- suppor t TBMs,at t ent ion should be given to t he r isk ofj amming of t he machine induced by thedensit y of a networ k of discont inuit ieswhich could quit e r apidly lead to doubt -f ul st abil i t y of the t er r ain. The ex ist enceof unconsolidated inf i l l ing mater ial canaggr avate t he r esult ing instabili t y .

The pr esence of maj or discont inuit iescan have a maj or ef fect on t he choice oft unnell ing technique.

Slur r y shi el ds and compr essed- ai rTBMs ar e gener ally mor e sensit ive t ot he pr esence of discont inui t ies t hanEPBMs. If t her e ar e maj or discont inui-t ies (high densit y of f r actur at ion), thecompr essed- air conf inement TBM mayhave t o be eliminated f r om the possibler ange.

In gener al t he over all per meabil i ty of theter r ain should be examined in conj unc-t i on w i t h i t s di scont inui t i es bef or eselect ing t he type of conf inement .

2 . 4 - Alterability

Al t er abi l i t y char act er ist ics concer nt er r ai n t hat i s sensi t iv e t o w at er .Alt er abili t y data should be obtained att he ident if icat ion st age.

Special at t ent ion should be given t o alte-r abil i t y when mechanized t unnell ing is t ot ake place in water - sensit iv e gr oundsuch as cer tain molasses, mar ls, cer t ainschist s, act ive clays, indur ated clays,etc.

Alt er abil i t y has an ef f ect on conf ine-ment - t ype TBMs; it can r esult in changesbeing made to t he design of t he machineand t he choice of addit ives.

2.5 - Water chemistry

Pr oblems r elated t o t he aggr essiv it y ort he degr ee of pollut ion of water mayar ise in ver y specif ic cases and have t obe dealt w it h r egar dless of t he t unnell ingpr inciples adopted.

Wit h conf inement - t ype TBMs t his par a-meter may be decisive because of i t sef f ect on t he qualit y of t he slur r y oraddit ives.

3 - MECHANICAL PA R A M E-T E R S

3 . 1 - Stre n g t h

In t he case of r ock, t he essent ial mecha-nical cr it er ia ar e the compr essive andtensile st r ength of the t er r ain, f or t heycondit ion t he ef f icacy of excavat ion.

In sof t gr ound, t he essent ial cr it er ia ar ecohesion and t he angle of f r ict ion, f ort hey condit ion t he hold- up of t he f ace andof t he excavat ion as a whole.

The ver y high st r engths of some r ocksexclude t he use of boom- t ype t unnell ingmachines (unless t hey ar e highly cr ac-ked). Gr ipper - t y pe t unnel bor ing andr eaming machines ar e ver y sensit ive t olow - st r ength gr ound and may r equir especial adaptat ion of t he gr ipper pads.For main- beam and shield TBMs alike,t he machine ar chit ectur e, t he installedpower at t he cut t er head, and t he choiceand design of cut t ing t ools and cut t er headar e condit ioned by t he st r ength of t hegr ound.

If t her e is any chance of t unnel bear ingcapaci t y being insuf f i cient , specialt r eat ment may be necessar y f or t hemachine to advance.

3.2 - Deform a b i l i t y

Defor mabil i ty of t he t er r ain may causej amming of the TBM, especially in t heev ent of conver gence r esul t ing f r omhi gh s t r esses ( see par agr aph 1 ,“ Natur al const r aint s” ).

In the case of t unnel r eamer s and open-f ace or mechanical- suppor t TBMs, t hiscr it er ion af f ects the appr eciat ion of t her isks of cut ter head or shield j amming.

In the case of excessively defor mablemater ial, t he design of TBM gr ipper padsw il l have t o be st udied car efully . The

Choosing mechanized tunnelling techniques

IV-21

APPENDIX 2

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Choosing mechanized tunnelling techniques

defor mabil it y of the sur r ounding gr oundalso af f ect s TBM guidance. If t he t unnell ining is er ected t o t he r ear of the t ails-kin, at t ent ion should be paid to t he r iskof defer r ed defor mat ion.

In gr ound t hat swel ls in contact w it hw at er , t he r esul t ing di f f icul t ies f oradvancing t he machine ar e compar ablefor both slur r y shield and EPB machines,in so f ar as t he swell ing is due t o t he dif -f usion and absor pt ion of water w it hin t hedecompr essed gr ound ar ound t he t unnel.Compr essed- air TBMs ar e less sensi-t ive t o t his phenomenon.

3.3 - Liquefaction potential

Not applicable, except if t her e is a r iskof ear t hquake or if t he gr ound is par t i-cular ly sensit ive (satur ated sand, et c.).

4 - HYDROGEOLOGICALPA R A M E T E R SThe pur pose of examining t he hydr ogeo-logical par ameter s of t he t er r ain is t oensur e t hat it w il l r emain st able in t heshor t ter m. The pr esence of high waterpr essur es and/ or potent ial inf low r atesent r aining mater ial w il l pr ohibit t he useof boom- t ype machines and open- f ace ormechanical - suppor t machines unlessaccompany ing measur es such as gr oundimpr ov ement , gr oundw ater lower ing,et c. ar e car r ied out .

Water pr essur e is also decisive whengeological accident s (e.g. my lonit e) haveto be cr ossed, ir r espect ive of whetheror not t hey ar e inf i l led w ith loose soil.

Gr ound per meabil i t y and hydr ostat icpr essur e ar e decisive f or TBMs usingcompr essed- air , slur r y , or EPB conf i-nement . Compr essed- air machines mayeven be r ej ected because of t hese f ac-t or s, and t hey ar e par t icular ly decisivefor EPBMs when t her e ar e likely t o besudden var iat ions in per meabili t y . Forslur r y shield TBMs, t he ef f ects of t hesepar ameter s ar e at t enuated by t he f actt hat a f luid is used for mucking out .

5 - OTHER PA R A M E T E R S

5.1 - Abrasiveness - Hard n e s s

Ex cessi v el y hi gh abr asi v eness andhar dness make it impossible or unecono-m i c t o use boom- t y pe t unnel l i ngmachines.

Abr asiveness and har dness can be deci-siv e w i t h r espect t o t ool w ear , t hest r uctur e of t he cut t er head, and ex t r a-ct ion systems (scr ew conveyor , slur r ypipes, et c.) . How ev er , t he ex pect edwear can be counter ed by using bor ingand/ or ex t r act ion addit ives and/ or pr o-t ect ion or r einf or cement on sensit ivepar t s.

5.2 - Sticking - Clogging

When t he potent ial t he mat er ial t o beexcavated has t o st ick or clog is known,the cut t er s of boom- t ype unit s, t unnelr eamer s, or shield TBMs can be adaptedor use of an addit ive env isaged.

This par ameter alone cannot exclude atype of shield TBM; it is t her efor e notdecisive f or f ace- conf inement shields.However , t he t r end f or t he gr ound t ost ick must be examined w it h r espect t ot he development of addi t ives ( f oam,admix tur es, et c.) and t he design of t heequipment f or chur ning and mix ing t hest icky spoil (agit at or s, j et t ing, et c.).

The t r anspor t of muck by t r ains and/ orconveyor s is par t icular ly sensit ive t othis par ameter .

5.3 - Ground/machine friction

For shield TBMs t he pr oblem of gr oundfr ict ion on t he shield can be cr it ical ingr ound wher e conver gence is high.

Wher e t her e is a r eal r isk of TBM j am-ming (conver gence, swell ing, dil i t ancy ,et c.) t his par ameter has a par t icular lyimpor t ant ef f ect on t he design of t heshield.

The lubr icat ion pr ov ided by t heir bento-nit e slur r y makes slur r y shield TBMsless suscept i bl e t o t he pr oblems ofgr ound/ machine f r ict ion.

5.4 - Presence of gas

The pr esence of gas in t he gr ound candeter mine t he equipment f i t t ed t o t hemachine.

6 - PROJECT CHARACTERIS-T I C S

6.1 - Dimensions and sections

Boom- t ype units can excavate tunnels ofany shape and sect ional ar ea. ShieldTBMs, main- beam machines, and r ea-

mer s can excavate t unnels of constantshape only . The sect ional ar ea t hat canbe excavated is r elat ed to t he st abil i t yof t he f ace.

The sect ional ar ea of t unnels is decisivef or l ar ge- di amet er EPBMs (pow err equir ed at t he cut t er head).

The length of t he pr oj ect can have anef f ect on slur r y shield TBMs (pumpingdist ance).

6.2 - Ve rtical alignment

The l i m i t s i mposed on t unnel l i ngmachines by t he v er t ical pr of i le ar egener ally those of t he associated logis-t ics. Main- beam tunnel bor ing and r ea-ming machines can be adapted t o bor einclined t unnels, but t he r equir ement f orspecial equipment t akes t hem beyond t hescope of t hese r ecommendat ions.

Wit h boom- t ype units and open- f ace ormechani cal - suppor t TBMs, w at erinf low can cause pr oblems in downgr adedr ives.

6 . 3 - Horizontal alignment

❑ The use of boom- type unit s imposes nopar t icular const r aint s.

❑ The use of main- beam tunnel bor ingand r eaming machines and of shield TBMsis l imit ed to cer t ain r adii of cur vatur e( ev en w i t h ar t i c ul at i ons on t hemachines).

❑ Wi t h shi el d TBMs t he al i gnmentaf t er / befor e br eak- ins and br eakout sshould be st r aight f or at least tw ice t helength of the shield (since it is impossiblet o st eer t he machine when it is on its sl idecr adle).

6 . 4 - Enviro n m e n t

6.4.1 - Sensitivity to settlement

Since boom- t ype unit s, t unnel r eamer s,main- beam TBMs, and open- face shieldTBMs do not gener al l y pr ov i de anyimmediate suppor t , t hey can engenderset t lement at t he sur f ace. Set t lementw il l be par t icular ly decisive in ur ban orsensit ive zones (t r ansit s below r outesof communicat ion such as r ai lw ay s,pipelines, et c.).

Sensit iv it y t o set t lement is gener allydecisive f or all TBM t ypes and can leadto exclusion of a given t echnique.

Open- f ace or mechanical- suppor t shieldTBMs ar e not suit able f or use in ver y

IV-22

Page 117: Recommendations ITA TBM

defor mable gr ound. If t he t unnel l ining iser ected t o t he r ear of t he t ailskin, at t en-t ion should be paid t o the r isk of defer -r ed def or mat ion of t he sur r oundinggr ound.

With conf inement - t ype TBMs, cont r ol ofset t lement is closely l inked to t hat ofconf inement pr essur e.

Wit h compr essed- air shields t he r isk ofset t lement lies in loss of air (sudden orgr adual).

Wit h slur r y shield TBMs t he r isk l ies int he qualit y of t he cake and in t he r egula-t ion of t he pr essur e. In r elat ion t o t his,t he “ air bubble” conf inement pr essur er egulat ion sy st em per f or ms par t icu-lar ly well.

Wit h EPBMs t he r isk lies in less pr eciser egulat ion of t he conf inement pr essur e.Mor eover , the annular space ar ound t heshield is not pr oper ly conf ined, unlessar r angements ar e made t o inj ect slur r yt hr ough the cans.

6.4.2 - Sensitivity to disturbance andwork constraints

Slur r y shield machines r equir e a lar gear ea at t he sur f ace f or the slur r y sepa-

r at ion plant . This const r aint can have anef f ect on t he choice of TBM t ype or evenbe decisive in int ensively built - up zones.

The addit ives int r oduced int o t he cut te-r head chamber of shield TBMs (bento-ni t e, poly mer , sur f act ant , et c.) mayimply const r aint s on disposal of spoil.

6 . 5 - Anomalies in gro u n d

6.5.1 - Ground/accident hetero g e n e i-t y

Mixed har d r ock/ sof t gr ound gener allyimplies f ace- stabil it y and gr ipping pr o-blems f or t unnell ing t echniques w ith noconf inement , and also int r oduces a r iskof cav ing- in of t he r oof wher e the gr oundis sof t est .

6.5.2 - Natural and artificial obs-t a c l e s

For “ open” techniques it is essent ial t obe able t o detect geological accident s. Forconf inement t echniques at t ent ion shouldbe paid t o t he pr esence of obst acles,whether natur al or ar t if icial. Obstaclescan hav e an ef f ect on t he choice ofmachine, depending on t he dif f icult ies

encounter ed in over coming t he obstacleand t he need to wor k f r om the cut t er headchamber .

Compr essed- ai r w or k necessar y f ordet ect ing and deal ing w i t h obst aclesr equir es r eplacement of t he pr oducts int he cut t er head chamber ( pr oduct sdepending on t he conf inement method)w it h compr essed air .

The wor k r equir ed f or r eplacing them is:

❑ f aster and simpler wit h a compr es-sed- air TBM (in pr inciple)

❑ easy w it h a slur r y shield TBM

❑ longer and mor e dif f icult w it h an ear t hpr essur e balance machine (ex t r act ion oft he ear t h and subst itut ion w it h slur r y t of or m a sealing f i lm, f ol lowed by r emo-val of the bulk of t he slur r y and r eplace-ment w it h compr essed air ).

6.5.3 - Vo i d s

Depending on t heir size, t he pr esence ofv oids can engender v er y substant ialdev iat ion f r om the design t r aj ector y ,especially ver t ically . They can also be asour ce of dist ur bance t o t he conf inementpr essur e, par t icular ly w it h compr es-sed- air or slur r y shield TBMs.

Choosing mechanized tunnelling techniques

IV-23

APPENDIX 3

Ground classification table (cf. GT7)

Cat égor y Descr ipt ion Ex amples RC (Mpa)

R1 Ver y st r ong r ock St r ong quar t zi t e and basal t > 200

R2a Ver y st r ong gr ani t e, por phy r y , v er y st r ongSt r ong r ock sandst one and l imest one 200 à 120

R2b Gr ani t e, v er y r esist ant or sl ight ly dolomi t i zed sandst one and 120 à 60l imest one, mar ble, dolomi t e, compact conglomer at e

Or dinar y sandst one, si l i ceous schist or R3aModer at ely st r ong r ock schist ose sandst one, gneiss

60 à 40

R3b Clay ey schist , moder at ely st r ong sandst one and l imest one, 40 à 20compact mar l , poor ly cement ed conglomer at e

Schist or sof t or highly cr acked l imest one, gy psum, 20 à 6R4 Low st r engt h r ock highly cr acked or mar ly sandst one, puddingst one, chalk

R5 a Ver y low st r engt h r ock and Sandy or clay ey mar ls, mar ly sand, gy psumconsol idat ed cohesiv e soi l s or w eat her ed chalk

6 à 0, 5

R5b Gr av el ly al luv ium, nor mal ly consol idat ed clay ey sand < 0, 5

R6aPlast ic or sl ight ly consol idat ed soi l s Weat her ed mar l , plain clay , clay ey sand, f ine loam

R6b Peat , si l t and l i t t le consol idat ed mud, f ine non- cohesiv e sand

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APPENDIX 3

Mechanized tunnelling data sheets (up to 31/12/99).

1 Echaillon D 68 1972-1973 43 62 5 .8 0 Gneiss, f lysch, limest one Wirt h2 La Coche D 77 1972 -1973 5287 3.0 0 Limestone, sandst one, breccia Robbins3 CERN SPS H 64 1973 -1974 65 51 4 .8 0 Molasse Robbins4 RER Chât elet -Gare de Lyon C 64 1973 -1975 51 00 7 .00 Limest one Robbins5 Belledonne D 64 1974-1978 9998 5.8 8 Schist , sediment ary granit e Wirt h6 Bramefarine D 67 1975 -1977 37 00 8 .1 0 Limest one, schist Robbins7 Lyons met ro - Crémaillère C 64 1976 220 3.0 8 Gneiss, granit e Wirt h8 Galerie du Bourget C 67 1976 -1978 48 45 6 m2 Limest one, molasse Alpine9 Monaco - Service t unnel H 64 1977 913 3 .30 Limest one, marne Robbins

10 Grand Maison - Eau Dolle D 64 1978 839 3.6 0 Gneiss, schist , dolomit e Wirt h1 1 West ern Oslof jord G 77 1978 -1984 10500 3.0 0 Slat e, limest one, igneous rock Bouygues 12 Brevon D 66 1979 -1981 41 50 3 .0 0 Limest one, dolomite, other Bouygues

calcareous rock (malm)1 3 Grand Maison D 75 1979-1982 54 66 3 .60 Gneiss, schist Wirt h

( penstocks and service shaf t )1 4 Marignan aqueduct F 66 1979 -1980 480 5.52 m2 Limest one Alpine1 5 Super Bissort e D 73 1980 -1981 29 75 3 .60 Schist , sandst one Wirt h1 6 Pouget D 66 1980 -1981 39 99 5 .0 5 Gneiss Wirt h1 7 Grand Maison - Vaujany D 75 1981-1983 5400 7.7 0 Lipt init e, gneiss, amphibolit e Robbins18 Vieux Pré D 68 1981-1982 1257 2.90 Sandst one, conglomeratee Bouygues19 Haut e Romanche Tunnel D 73 1981 -1982 28 60 3 .60 Limest one, schist , crystalline sandst one Wirt h2 0 Cilaos F 80 1982 -1984 57 01 3 .0 0 Basalt , t uf f Wirt h21 Monaco - t unnel No. 6 A 66 1982 183 5.0 5 Limest one, dolomit e Wirt h2 2 Ferrières D 79 1982 -1985 43 13 5 .90 Schist , gneiss Wirt h23 Durolle D 79 1983 -1984 21 39 3 .4 0 Granit e, quart z, microgranit e Wirt h24 Mont fermy D 80 1983 -1985 50 40 3 .5 5 Gneiss, anat exite, granit e Robbins2 5 CERN LEP (machines 1 and 2) H 82 1985 -1986 14680 4 .5 0 Molasse Wirt h 2 6 CERN LEP (machine 3) H 82 1985-1987 4706 4.5 0 Molasse Wirt h2 7 Val d' Isère funicular B 97 1986 16 89 4 .20 Limest one, dolomit e, cargneule Wirt h

(cellular dolomit e)2 8 Calavon and Luberon F 97 1987 -1988 27 87 3 .4 0 Limest one Wirt h29 Takamaka II D 101 1985 -1987 48 03 3 .20 Basalt , t uf f , agglomerat es Bouygues3 0 Oued Lakhdar D 101 1986-1987 6394 4.56 / 4.80 Limest one, sandst one, marl Wirt h3 1 Paluel nuclear power plant E 105 1980 -1982 24 27 5 .0 0 Chalk Zokor3 2 Penly nuclear power plant E 105 1986 -1988 25 10 5 .1 5 Clay Zokor 3 3 Lyons river crossing - met ro line D C 106 1984-1987 2 x 1230 6.5 0 Recent alluvium and granit ic sand Bade3 4 Lille met ro, line 1b - Package 8 C 106 1986-1987 1000 7.6 5 Whit e chalk and f lint FCB/ Kawasaki3 5 Lille met ro, Line 1b - Package 3 C 106 1986-1988 3259 7.7 0 Clayey sand and silt Herrenknecht3 6 Villejust t unnel B 106 1986 -1988 48 05 9 .25 Font ainebleau sand Bade/ Theelen

+ 4798 (2 machines)3 7 Bordeaux: Cauderan-Naujac G 106 1986-1988 1936 5.0 2 Sand, marl and limest one Bessac3 8 Caracas met ro: package PS 01 C 107 1986 -1987 2 x 1564 5 .7 0 Silt y-sandy alluvium, gravel, and clay Lovat 39 Caracas met ro: package CP 03 C 107 1987 2 x 2131 5.70 Weat hered micaschist and silt y sand Lovat 4 0 Caracas met ro: package CP 04 C 107 1987 -1988 2 x 714 5.7 0 Micaschist Lovat 4 1 Singapore met ro: package 106 C 107 1985 -1986 26 00 5 .8 9 Sandst one, marl and clay Grosvenor42 Bordeaux: " boulevards" G 113 1989 -1990 14 61 4 .36 Karst ic limest one and alluvium Bessac

main sewers Ø38004 3 Bordeaux: Avenue de la Libérat ion G 113 1988 -1989 918 2.9 5 Karst ic limest one and alluvium Bessac

Ø22004 4 St Maur-Crét eil, sect ion 2 G 113 1988 -1990 15 30 3 .3 5 Old alluvium and boulders FCB4 5 Crosne-Villeneuve St Georges G 113 1988 -1990 911 2.5 8 Weat hered marl and indurat ed limest one Howden46 Channel Tunnel T1 B 114 1988 -1990 15618 5 .7 7 Blue chalk Robbins4 7 Channel Tunnel T2-T3 B 114 1988 -1991 20009 8 .7 8 Blue chalk Robbins/

+18 860 Kawasaki

*AITES classif icat ion of project t ypesA road t unnels - B rail t unnels - C met ros - D hydropower t unnels - E nuclear and fossil-fuel power plant t unnels - F wat er t unnels - G sewers-H service t unnels - I access inclines - J underground st orage facilit ies - K mines -

Dat eBoredlengt h (m)

Boreddiameter

(m)

GeologyProject

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Choosing mechanized tunnelling techniques

48 Channel Tunnel T4 B 114 1988-19 89 3162 5.61 Grey and whit e chalk Mit subishi49 Channel Tunnel T5-T6 B 1 14 19 88 -1 990 2 x 326 5 8.64 Grey and whit e chalk Mit subishi50 Sèvres - Achères: Package 3 G 1 21 1989 -1 991 3550 4.05 Coarse limest one, sand, upper Landenian

clay ( fausses glaises) , plast ic clay, HerrenknechtMont ian marl, chalk

51 Sèvres - Achères: Packages 4 and 5 G 1 21 19 88 -1 990 3312 4.8 Sand, upper Landenian clay ( fausses glaises) , plast ic clay, Mont ian marl and limest one, chalk Lovat

53 Orly Val: Package 2 C 1 24 1989 - 1990 1160 7.64 Marl wit h beds of gypsum Howden54 Bordeaux Caudéran -

Naujac Rue de la Libert é G 1 26 1 991 150 3.84 Karst ic limest one Bessac55 Bordeaux Amont Taudin G 1 26 1 991 5 00 2.88 Alluvium and karst ic limest one Howden56 Rouen "Mét robus" C 1 26 1 993 8 00 8.33 Black clay, middle Albian sand and Gault clay Herrenknecht57 Toulouse met ro: Package 3 C 1 31 19 89 -1 991 3150 7.65 Clayey-sandy molasse and beds FCB /

of sandst one Kawasaki58 Toulouse met ro: Packages 4 and 5 C 131 19 90 -1991 1587 5.6 Molasse Lovat

+1 48759 Lille met ro: Line 2 Package 1 C 1 32 1992 - 1994 5043 7.65 Flanders clay FCB60 Lille met ro: Line 2 Sect ion b C 132 1992 - 1993 1473 7.65 Chalk, clay, and sandy chalk FCB61 St Maur: VL3 c main sewer G 133 1992 - 1994 1350 3.5 Very het erogenous plast ic clay, sand,

coarse limest one,andupper Landenian clay Herrenknecht62 Lyons met ro: Line D

Vaise - Gorge de Loup C 1 33 1993 - 1995 2 x 875 6.27 Sand, gravel, and clayey silt Herrenknecht63 METEOR Line 14 C 1 42 1993 - 1995 4500 8.61 Sand, limest one, marl,upper Lut et ian

marl/ limest one ( caillasses) HDW64 RER Line D Chat elet / Gare de Lyon C 142 1993 - 19942 x 160 0 7.08 Coarse limest one Lovat65 Cleuson Dixence Package D D 142 1994 - 1996 2300 4.77 Limest one, quart zit es, schist , sandst one Robbins

Inclined shaft66 Cleuson Dixence Inclined shaf t D 1 42 1994 - 1996 4 00 4.4 Limest one, schist , sandst one Lovat67 Cleuson Dixence Package B

Headrace tunnel D 1 53 1994 - 1996 7400 5.6 Schist and gneiss Wirt h68 Cleuson Dixence Package C

Headrace t unnel D 1 52 1994 - 1996 7400 5.8 Schist , micachist , gneiss, and quartzit e Robbins69 EOLE B 1 46199 3 - 1996 2 x 1700 7.4 Sands, marl and ' caillasse' marl/ limest one,

sandst one and limest one Voest Alpine70 Sout h-east plat eau G 146 1994 - 1997 3925 4.42 Molasse sand, moraine, alluvium NFM

out fall sewer (EPSE)71 Cadiz: Galerie Guadiaro Majaceit e F 1 48 1995 - 1997 12 200 4.88 Limest one, consolidat ed clay NFM/ MHI72 Lille met ro Line 2 Package 2 C 1 48 1995 - 1997 3962 7.68 Flanders clay FCB73 Nort h Lyons bypass,

Caluire t unnel, Nort h t ube A 1 50 1994 - 1996 3252 11.02 Gneiss, molasse, sands and conglomerat e NFM74 Nort h Lyons bypass, Caluire t unnel,

Sout h t ube A 1 50 1997 - 1998 3250 11.02 Gneiss, molasse, sand, and conglomerat e NFM75 Storebaelt rail t unnels B 150 1990 - 1995 14 824 8.78 Clay and marl Howden76 St rasbourg t ram line C 1 50 1992 - 1993 1198 8.3 Sands and grav iers Herrenknecht77 Thiais main sewer Package 1 G 154 1987 - 1989 4404 2.84 Marl and clay Lovat78 Ant ony urban area main sewer G 1 54 1 989 1483 2.84 Alluvium, limest one, marl Lovat79 Fresnes t ransit G 1 54 1 991 280 2.84 Marl and alluv ium Lovat80 Main sewer beneat h CD 67 G 154 1991 6 70 2.84 Marl Lovat

road in Ant ony81 Duplicat ion of main sewer,

Rue de la Barre in Enghien G 154 1992 - 1993 8 07 2.84 Sand, marly limest one, marl Lovat82 Bièvre int ercept or G 1 54 1 993 1000 2.84 Marl and alluv ium Lovat83 Duplicat ion of main sewer,

Ru des Espérances - 8t h t ranche G 156 1993 - 1994 1387 2.54 Limestone, sand Lovat84 Duplicat ion of main sewer,

Ru des Espérances - 9t h t ranche G 1 56 1995 - 1996 1200 2.54 Coarse limest one, marly limest one Lovat85 Duplicat ion of main sewer,

Ru des Espérances - 10t h t ranche G 1 56 1996 - 1997 4 69 2.54 Marly limest one Lovat

(APPENDIX 3)

Dat eBoredlengt h

(m)

Boreddiamet er

(m)

GeologyProject