TBM IN SOFT GROUND - Warsaw University of .Course in Tunnelling and Tunnel Boring Machine ... Astaldi

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  • Course in Tunnelling and Tunnel Boring Machine

    Kurs w zakresie drenia tuneli oraz maszyny drcej

    Lecture: Eng. Marco Barbanti Astaldi S.p.A.

    TBM IN SOFT GROUND

    13.10.2011

  • EARTH PRESSURE BALANCE SHIELD

    1. Tunnel face

    2. Cutting wheel

    3. Excavation chamber

    4. Pressure bulkhead

    5. Thrust cylinders

    6. Screw conveyor

    7. Segment erector

    8. Segmental Lining

    Course in Tunnelling and Tunnel Boring Machine

    Kurs w zakresie drenia tuneli oraz maszyny drcej

  • EPB PRINCIPLE

    water water water water pressurepressurepressurepressure

    earth earth earth earth pressurepressurepressurepressure

    increasing / debasing thrust force increasing / debasing thrust force increasing / debasing thrust force increasing / debasing thrust force

    increasing / debasing advance rate increasing / debasing advance rate increasing / debasing advance rate increasing / debasing advance rate

    The face support is provided by the excavated ground that is kept under pressure

    inside the excavation chamber by balancing the volume of the extracted and

    excavated material and by the thrust jacks on the shield.

    Excavation debris is removed from the excavation chamber by a screw conveyor that

    allows the pressure control by variation of its rotation speed.

    Course in Tunnelling and Tunnel Boring Machine

    Kurs w zakresie drenia tuneli oraz maszyny drcej

  • EPB-SHIELD.

    FOUR MODI: OPEN TO CLOSED.

    closed mode

    closed (compressed air) mode

    open mode

    slurry mode

    decreasing face stability

    decreasing water pressure

    slurry

    Course in Tunnelling and Tunnel Boring Machine

    Kurs w zakresie drenia tuneli oraz maszyny drcej

  • EPB-SHIELD.

    MODE: SLURRY / CLOSED.

    slurry

    Course in Tunnelling and Tunnel Boring Machine

    Kurs w zakresie drenia tuneli oraz maszyny drcej

  • EPB-SHIELD.

    MODE: CLOSED (compressed air) / OPEN.

    Course in Tunnelling and Tunnel Boring Machine

    Kurs w zakresie drenia tuneli oraz maszyny drcej

  • EPB-SHIELD: THE SCREW CONVEYOR

    Course in Tunnelling and Tunnel Boring Machine

    Kurs w zakresie drenia tuneli oraz maszyny drcej

  • EPB-SHIELD: SCREW CONVEYOR

    Course in Tunnelling and Tunnel Boring Machine

    Kurs w zakresie drenia tuneli oraz maszyny drcej

  • 0,0

    0,3

    0,6

    0,9

    1,2

    1,5

    1,8

    2,1

    2,4

    2,7

    3,0

    Erd

    dru

    ck S

    ch

    ne

    cke

    nf

    rde

    rer

    [b

    ar]

    0

    0,1

    0,2

    0,3

    0,4

    0,5

    Dru

    cka

    bb

    au

    pro

    We

    nd

    el

    [bar]

    pressure screw conveyor outlet

    pressure screw conveyor inlet

    decreasing pressure per helix

    EPB-SHIELD.SCREW CONVEYOR. PRESSURE DISTIBUTION.

    earth pressure screw conveyor [bar]

    decreasing pressure per helix [bar]

    Course in Tunnelling and Tunnel Boring Machine

    Kurs w zakresie drenia tuneli oraz maszyny drcej

  • SCREW CONVEYOR DETAILS GAUILLOTTINE SAFETY GATE

    The lower part of the bulkhead in the front

    shield of an EPBS must be equipped with a

    safety gate, which can be closed when the

    screw conveyor is retracted for

    maintenance. This allows the complete

    insulation of the plenum, avoiding water

    /material inflow during maintenance.

    Course in Tunnelling and Tunnel Boring Machine

    Kurs w zakresie drenia tuneli oraz maszyny drcej

  • EPB-SHIELD:

    APPLICATION RANGE AND CONDITIONING.

    open shield

    possible

    conditioning necessary foam and additives

    (clogging - adhesion of soil)

    silty sand

    foam

    coarse soil

    foam + polymers

    very coarse soil

    foam, polymers

    and fuller

    gravelsandsiltclay

    sieve size [mm]

    Course in Tunnelling and Tunnel Boring Machine

    Kurs w zakresie drenia tuneli oraz maszyny drcej

  • GEOTECHNICS: SOIL RECOMMENDATION

    Course in Tunnelling and Tunnel Boring Machine

    Kurs w zakresie drenia tuneli oraz maszyny drcej

  • 0,30

    0,40

    0,50

    0,60

    0,70

    0,80

    0,90

    1,00

    1,10

    1,20

    1,30

    1,40

    1,50

    0 10 20 30 40 50 60 70

    Plasticity Index IP [%]

    Co

    ns

    iste

    nc

    y I

    nd

    ex

    I C

    Low clogging risk

    Medium clogging risk

    High clogging risk

    soft

    stiff

    hard-

    stiff

    hard

    pulpy

    FOAM: CLOGGING-ADHESION

    ON STEEL SURFACE

    Course in Tunnelling and Tunnel Boring Machine

    Kurs w zakresie drenia tuneli oraz maszyny drcej

  • Soil recommendation for EPB-mode:

    cohesive and plastic

    soft stiff consistency

    small inner angle of friction

    low permeability

    GEOTECHNICS.

    SOIL RECOMMENDATION.

    Course in Tunnelling and Tunnel Boring Machine

    Kurs w zakresie drenia tuneli oraz maszyny drcej

  • CONDITIONING AND FOAM GENERATION

    Tenside

    water

    Screw conveyor

    Pressure bulkhead

    Cutting wheel

    Air

    Liquid

    Additive

    Water

    Tenside

    Course in Tunnelling and Tunnel Boring Machine

    Kurs w zakresie drenia tuneli oraz maszyny drcej

    Polymer

  • FOAM: PROPERTIES

    Properties of foaming:

    plastic

    short term cohesion

    lower angle of friction

    lower permeability

    Different foams have different:

    foaming capacity

    stability

    Anti-clay capacity

    rheological impact (liquefaction / stiffening)

    drying-up capacity

    Advantages of foaming in soft soil:

    reduction of friction angle of soil

    short term cohesion of soil

    plasticity and lower permeability of soil

    lower wear

    lower torque

    short term stabilistation of face

    lower clogging

    soil structuring

    Course in Tunnelling and Tunnel Boring Machine

    Kurs w zakresie drenia tuneli oraz maszyny drcej

  • FOAM: CONDITIONING IN SOFT SOIL

    Low cohesive sand

    Short-term cohesion via foam

    Course in Tunnelling and Tunnel Boring Machine

    Kurs w zakresie drenia tuneli oraz maszyny drcej

  • foam

    screw conveyor

    belt conveyor

    Foam Injection Rate (FIR):

    FIR regulates amount of foam

    FIR correlates with pore volume

    FIR = volume foam / volume soil

    FIR correlates with advance rate

    FOAM: FOAM INJECTION RATE

    Course in Tunnelling and Tunnel Boring Machine

    Kurs w zakresie drenia tuneli oraz maszyny drcej

  • FOAM:FOAM EXPANSION RATE

    13 air13 air13 air13 air

    Additive (2 Additive (2 Additive (2 Additive (2 ---- 5%)5%)5%)5%)

    1 Liquid1 Liquid1 Liquid1 Liquid

    FER 14:1FER 14:1FER 14:1FER 14:1Water (95 Water (95 Water (95 Water (95 ---- 98%)98%)98%)98%)

    Foam Expansion Rate (FER):

    FER regulates quality

    low FER = wet foam

    high FER = dry foam

    FER = volume foam/volume liquid

    Course in Tunnelling and Tunnel Boring Machine

    Kurs w zakresie drenia tuneli oraz maszyny drcej

  • FOAM: CLOGGING,

    ANTI CLAY ADDITIVE.

    Use of Anti-clay-Additives in clay as well as in silt & sand:

    Problem

    - adhesion on steel surface

    - cohesion of greater clay lumps

    Conclusion

    - clogging of cutting wheel

    - clogging of screw conveyor or excavation chamber

    Course in Tunnelling and Tunnel Boring Machine

    Kurs w zakresie drenia tuneli oraz maszyny drcej

  • Foam generator

    short distance to

    tunnel face

    FOAM CONTROL AND FOAM GENERATOR.

    Automatic Mode

    Semi-Automatic Mode (FER)

    Manual Mode (FIR/FER)

    Course in Tunnelling and Tunnel Boring Machine

    Kurs w zakresie drenia tuneli oraz maszyny drcej

  • EPB TBM vs. SLURRY TBM

    Course in Tunnelling and Tunnel Boring Machine

    Kurs w zakresie drenia tuneli oraz maszyny drcej

  • TBM DESIGN CONSIDERATION

    Geological conditions

    Grain size distribution

    Water level and pressure

    Presence of boulders or obstructions along the alignment

    Availability of use of conditioning agents and /or bentonite

    Feasibility and space for treatment plant

    Final use and discharge of excavated muck

    Experience of contractor

    Capital cost

    CRITERIA FOR SELECTION OF EPB OR SPB

    Course in Tunnelling and Tunnel Boring Machine

    Kurs w zakresie drenia tuneli oraz maszyny drcej

  • SIMILARITIES OF DESIGN

    The basic design of an EP TBM and a SPB TBM are quite similar.

    The overall appearance and many systems from one type are used directly on the other.

    These similarities include:

    Main structures

    Propulsion

    Trailing gantry Structure

    Segment Erector and handling

    Course in Tunnelling and Tunnel Boring Machine

    Kurs w zakresie drenia tuneli oraz maszyny drcej

  • EPB vs. SLURRY

    Overall simpler system to learn,operate and maintainApplicable to a wider range ofgroundsRequires limited addition ofconditioning materials (lower consumption of additives no slurry circuit) Incase of face collapse amount of ground loss is limited

    Overall a more complicatedsystem (to learn, operate andmaintain)Applicable to a restricted range ofgroundsRequires extensive addition ofmaterials In case of face collapse amount ofground loss is considerable

    EPB TBM SLURRY TBM

    Course in Tunnelling and Tunnel Boring Machine

    Kurs