Ground types SIN - srmeg.org.sg Ground Types are ground (rock masses) ... Ground types TBM segmental lining Short Course Singapore 11 Klima, Schubert 22 Ground types Discontinuity controlled block fall. 12 Short Course Singapore 11 Klima, Schubert 23 Ground types Finite element model TBM Short Course Singapore 11 Klima, Schubert 24 Ground types

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    DETERMINATION OF GROUND PROPERTIES

    and

    DEFINITION OF GROUND TYPES

    2Short Course Singapore 11 Klima, Schubert

    Ground types

    OBJECTIVES

    Physical and geometrical parameters of the ground are required for various purposes:

    Assessment of potential failure modes Estimation of stresses and displacements Evaluation of required support Selection of excavation method Estimation of water inflow Estimation of tool wear and progress rate etc.

    Necessary for any analytical or numerical design approach.

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    3Short Course Singapore 11 Klima, Schubert

    Ground types

    STRATEGY

    Get overview on the geological/geotechnical conditions of the project

    Distinguish engineering-geological units, with emphasis on lithological and structural characteristics

    Describe the characteristics of each unit and make a sketch of a representative volume, preferably in 3D

    Identify characteristic features of each unit, eg intact rock strength, anisotropy, shear strength of discontinuities, etc.

    Determine the degree of acceptable simplification; a simplified model should still allow capturing characteristic behaviours

    Split units into Ground Types, if variation of properties is large; determine relevant parameters for each GT

    4Short Course Singapore 11 Klima, Schubert

    Ground types

    Determination of properties

    Which properties do we need? What do we use them for? Whenever possible, try to use direct methods for an

    estimate of the ground parameters

    Using empirical methods cannot be completely avoided. When using empirical methods for the determination of

    parameters check their plausibility

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    5Short Course Singapore 11 Klima, Schubert

    Ground types

    GROUND TYPES

    Definition: Ground Types are ground (rock masses) with similar properties (of a geotechnically relevant volume)

    Definition of geotechnically relevant parameters key parameters

    Evaluation of the parameter values and ranges Classification into Ground Types Description of Ground Types shall contain

    Rock/soil type Verbal description of composition and condition Sketch of representative volume Properties of intact rock and discontinuities Properties of rock mass (range); in case of anisotropy

    properties in different directions

    6Short Course Singapore 11 Klima, Schubert

    Ground types

    Parameter representative value/rangeEngineering geological unit

    Limestone (limestone, and marble)secondary: dolomite

    LithologyGrey and sometimes dark grey limestone with transitions to marble ot to domomite (marble), limestone breccia (cemented)

    UCS [MPa] 30 - 80 (50 - 120*)

    c [MPa] 8 - 18 (12 - 20*) 45 6mi [-] 20 6 (15 2*)Braz. [MPa] 1,4 - 2,9 (range of lab results)E [GPa] 20 - 60 (40 - 80*) [-] 0,18 0,07 (0,2*)

    Abrasivity (low) abrasive CAI [-] 0,9 - 1,8

    General descriptionPartially bedded with spacing in a cm range, partially karst along jointsTeilweise with openings of mm to some cm (signs of weathering)

    Foliation / bedding, spacing

    bedded and thinly laminated; bedding only partially mechanically relevant

    foliation spacing 6 - 20 (partially 20)

    sf [] 35 - 45

    sf, rest [] 30 - 40

    size dom.: 2 - 20 cmsec.: 20 - 60 cm

    geometry generally blocky

    K,H [] 35 - 45

    K,H, rest [] 30 - 40

    GSI-classification Joints and bedding are dominating, blocks show size of cm to some dm, rough discontinuities GSI [-] 40 - 55

    UCSRM [MPa] 14,3 (6,6-25,5)

    cRM [MPa] 3,8 (1,9-6,3)RM [] 34,4 (31,1-37,5)RM [-]

    Elastic properties ERM [GPa] 15,8 (6,4-32,7)

    Remarks concerning grouting

    Remarks concerning swelling

    Dis

    cont

    inui

    ty

    Foliation / bedding, conditions

    Strength properties the rock mass strength is generally dominated by the discontinuities. Isotropic to slightly anisotropic

    Joints, block size and goometry

    manily narrow jointing and very narrow secondary jointing (incomplete healing); rarely medium jointing

    dom.: stepped to planar, rough partially oxidated (karstic joints)sec..: planar /rough to smooth; rarely clayey (sl)

    Joints / slickensides, conditions

    Interpretation of laboratory results, filed data and core logging

    Ground Type 4b Limestone and Marble (Permomesozoic), moderately to heavily fractured

    Short descritption Limestone and marble,moderately to heavily fractured

    Detailed rock mass description

    Inta

    ct ro

    ck

    Mechanical properties Isotropic to low anisotropic rock with high intact rock strength

    Gouting is possible up to a certain level (along joints), locally high grouting volumes possible due to open karst discontinuities

    planar to wavy, rough, partially oxidations, partially minor clay fillings

    Add

    ition

    al

    data

    no swelling potential

    Roc

    k m

    ass

    Representative core photos:

    Sketch:

    KB 17/07: limestone, bedded, with joints, fractrued, with karst

    KB 06/08: Limestone marble, tectonized, fractured

    Die dargestellte Gefgeneigung ist beispielhaft. Die tatschliche Gefgeorientierung zum Bauwerk kann davon stark abweichen.

    Remarks:

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    Case study:Evaluation of Construction Methods for the Mae Ngad Mae Kuang Project

    Alfred Fasching & Wulf Schubert, 3G

    Alois Vigl, viglconsult

    Chinda Sutiwanich, Panya

    8Short Course Singapore 11 Klima, Schubert

    Ground types

    The Project

    The Mae Kuang Dam Inflow Augmentation Project in theChiang Mai province includes a 23.1 km distribution tunnelwith approximately 5 m diameter, connecting the Mae Ngad and Mae Kuang reservoirs.

    Client: Royal Irrigation Department

    Feasibility and alignment studies were carried out in theprevious years, including geological investigations. In 2005 the alignment was fixed, and the tender designstarted.

    Construction start is planned for this year

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    9Short Course Singapore 11 Klima, Schubert

    Ground types

    INTAKE

    ADIT #5

    ADIT #6

    OUTLET

    Several alignments were studiedwith emphasis on minimizing risksassociated with tunnelling.

    Site installations are possible at theadits 5 and 6, and at the outlet

    Adit #5 required during operationfor depletion of tunnel

    10Short Course Singapore 11 Klima, Schubert

    Ground types

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    11Short Course Singapore 11 Klima, Schubert

    Ground types

    Longitudinal section

    quartzitic sandstoneshale and siltstone

    intercalations

    sheared shalechert and sandstone

    limestone blocksquartzitic sandstone with shale intercalations

    12Short Course Singapore 11 Klima, Schubert

    Ground types

    Method of evaluation

    Rock mass characterization Determination of Rock Mass Types (RMT) Assignment of physical parameters to each RMT Divide alignment into evaluation sections

    Evaluation of rock mass behaviour Evaluate response of rock mass to excavation under

    consideration of rock mass type, stresses, ground water, tunnel size and orientation for each section

    Assign construction measures Appropriate excavation and support methods for each

    behaviour type Evaluation of System Behaviour Assignment of time and costs

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    13Short Course Singapore 11 Klima, Schubert

    Ground types

    Distribution of Ground Types

    0

    1

    2

    3

    4

    5

    6

    7

    8

    9

    0 5.000 10.000 15.000 20.000

    station

    RM

    T

    0

    500

    1000

    1500

    2000

    2500

    3000

    over

    burd

    en

    14Short Course Singapore 11 Klima, Schubert

    Ground types

    Distribution of Behaviour Types

    0

    1

    2

    3

    4

    5

    6

    7

    8

    9

    10

    11

    0

    5000

    1000

    0

    1500

    0

    2000

    0

    station [m]

    Beh

    avio

    ur T

    ype

    0

    200

    400

    600

    800

    1000

    1200

    1400

    1600

    1800

    2000

    2200

    over

    burd

    en, w

    ater

    tabl

    e (m

    )

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    15Short Course Singapore 11 Klima, Schubert

    Ground types

    Options studied

    ADIT 6ADIT 5

    INTAKE OUTLET

    D&

    B

    TBM

    D&

    B

    D&B D&B D&B D&B

    OPTION 1

    ADIT 6ADIT 5

    INTAKE OUTLET

    D&B

    D& B

    TBM D&B TBM

    OPTION 2

    ADIT 6ADIT 5

    INTAKE OUTLETTBM TBM

    D&B

    D&B

    OPTION 3

    16Short Course Singapore 11 Klima, Schubert

    Ground types

    Tunnelling methods

    Drill & blast 4 excavation & support classes Round lengths from 1,0 to 3,0 m Support from spot bolting to full shotcrete lining with bolts

    TBM Double shield TBM chosen Open TBM considered earlier in the project was ruled out due

    to the requirement of smooth lining, and the existence of several fault zones

    Two segment types considered (standard + strong)

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    17Short Course Singapore 11 Klima, Schubert

    Ground types

    D&B tunnel support

    18Short Course Singapore 11 Klima, Schubert

    Ground types

    D&B tunnel support

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    19Short Course Singapore 11 Klima, Schubert

    Ground types

    Typical section adits

    20Short Course Singapore 11 Klima, Schubert

    Ground types

    Support Adits

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    21Short Course Singapore 11 Klima, Schubert

    Ground types

    TBM segmental lining

    22Short Course Singapore 11 Klima, Schubert

    G