EPB Short Course 2010

8/19/2019 EPB Short Course 2010

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EARTH PRESSURE BALANCED ( EPB )

NAT 2010 PORTLAND

SHORT COURSEPresented by:

Dennis Ofiara

Chief Engineer

Solon, Ohio


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PRESENTATION ITEMS

• 1. SHIELD MACHINE TYPE

• 2. OUTLINE OF EPB METHOD

• 3. EPB AND SLURRY SHIELDS

• 4. EPB SHIELD / STRUCTURE

• 5. SCREW CONVEYOR

• 6. ARTICULATION SYSTEM

• 7. BACKFILL

• 8. ADDITIVES

• 9. EPB OPERATION FLOW CHART

• 10. MUCK HAULAGE FOR EPB TUNNELS


3/94

1. SHIELD MACHINE TYPE

1-1 History

first shield first shield

In England under the sea mechanical shield EPB shield

(manual) (manual) slurry shield EPB with foam

1825 1914 1950s 1960s 1970s 1980s MARKET

year

http://www.jsce.or.jp/what/hakase/tunnel/05/images/col_img01_l.gif


4/94


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1-2 SHIELD MACHINE TYPE

manual shield

• open mode shield semi-mechanical shield

(no bulkhead at cutting area) mechanical shield

• Shield machine partial open mode shield Blind shield

(bulkhead with small opening)

Slurry shield

• closed mode shield

(with bulkhead at cutting area)EPB shield

bulkhead

segment

shield

soil discharge device

Excavation device

(under earth pressure) (no pressure)


6/94

CLOSED MODE SHIELD

Blind shield (reference)

6.32m blind shield1. soil is discharged from small opening,2. only for very soft geology,3. almost no demand nowadays,


7/94

Slurry shield

6.5m slurry 7.45m slurry


8/94

EPB shield

9.98m EPB 6.26m EPB

6.14m EPB 15.01m EPB


9/94

Lower torque Lower thrust

Difficult for gravel dischargeUSE JAW CRUSHER

Slurry volume and density control by

discharge pump, considering advance speed

Slurry keeps stability.

Less cutter wear

To slurry treatmentplant on the surface

Slurry shield explanation of features


10/94

2. OUTLINE OF EPB METHOD

2-1 Earth pressure control by soilEPB PRINCIPLE: DISCHARGED VOLUME PROPORTIONAL

TO SHIELD ADVANCE TO MAINTAIN EARTH PRESSURE

EARTH PRESSURE(SOIL + WATER)

ADDITIVE

MUMUCK CHAMBER AGITATOR

BULK HEAD

EARTH PRESSURE SENSOR

OPERATIONS

1. Fill excavated soil in muck chamber.

2. Inject additives in order to improve muck fluidity.

3. Rotate cutterhead to agitate muck and additives, and push thrust cylinders.

4. Control discharged muck volume by adjusting screw conveyor speed to meet excavation volume.

5. Monitoring earth pressure sensors on bulkhead.

SHIELDADVANCE m3

DISCHARGE

VOLUME m3


11/94

1. Versatility for wide range of geology;By selecting proper additives, EPB method can be applied for wide range of geology.Large sized gravel is also excavated and discharged by screw conveyor.

2. Totally economical method, generally;

Excavated soil can be normally disposed as it is (in case of foam type EPB). As slurry plant or equivalent large facilities is not necessary, total tunnel construction

cost is generally less than other methods like slurry method.

3. High stability of surface ground;

Geology is basically supported by excavated soil with additives, which brings lesssettlement of surface ground.

4. Simultaneous back fill;

As muck chamber and surrounding area of shield skin plate are filled with soil,simultaneous back filling is easier, which contributes to better stability of surface ground.

5. Space of launching shaft area;

Construction site for launching shaft can be minimized compared with slurry method,which is suitable in city area shaft.

2-2 Features of EPB method


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3. EPB AND SLURRY SHIELDS

application of geology

clay silt sandfine coarse

gravelsmallmid big

cobble

Slurry is better for

・

・Excavating under river or sea

・Excavating under high pressure

EPB is better for

Totally economical method

Excavating in gravel geology

Smaller space on surface

Particle diameter (mm)

○○E△○F

◎○D

◎◎C

○B△A

SLURRYEPB

○

--- most suitable

--- suitable

--- not suitable

○


13/94

Higher torque Higher thrust

Possible for gravel discharge

Earth pressure control by screw speed andgate opening ratio, considering advance speed

Excavated soil keeps stability.

Larger cutter wear

EPB shield explanation of features


14/94

Summary of EPB and Slurry

advantage

1. Suitable for excavationunder high undergroundwater pressure

2. Less wear of cutting toolsand steel structure.

3. Smaller TBM power--- torque and thrust force(TBM is cheaper.)

advantage

1.Economical system in total(TBM is more expensive, butno surface plant.)

2. Available for gravelexcavation

3. Smaller surface spaceis required.

summary

SLURRYEPBshield type


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4-2 Main components

shield : circular steel plate main body, which supports inside space from outside earth pressure

When articulation is applied, it is divided into front- and rear shields.

cutter head : rotating parts with cutting tools on front surface, which excavates the ground.

tail seal : seal to stop soil and water invasion at the end of rear shield

muck chamber : the space between cutter head and bulk head, which is filled with excavated soil.

thrust cylinder : hydraulic cylinders which are arranged circumferential area of shield and push machine to

advance forwards.

screw conveyor : soil discharge device, rotated by motors.screw gate : open/close gate of muck, located at the end of screw conveyor

erector : assembling device of segments, while gripping, rotating and positioning a segment one by one.

articulation cylinder: hydraulic cylinders which connect front shield and rear shield.

rotary joint : supplying device of hydraulic oil, additives, etc. from font shield (stationary) to

cutter head (rotating).

CHS : Cutter Head Support ,cutter head drive unit with main bearing, cutter head drive motors, etc.

segment feeder : supplying device of segments to erector back up gantries : a series of mounting structures which accommodate back up devices such as cabin,

power units, electrical devices ,belt conveyor, additive device, backfill device, etc.

connection bridge : connecting structure between shield and back up gantries.

bulkhead : pressure wall to separate pressurized area and non-pressurized area


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4. EPB SHIELD / STRUCTURE

shield

cutterhead

erector

screw conveyor

muck chamber

thrust cylinder

tail seal

cutter drive motor

articulation cylinder

bulk head

pedestal

crew gate

cutters

Typical EPB structure, with articulation, shaft screw, and spoke type cutterhead


17/94

SIMPLIFIED FORCES ACTING ON EPB SHIELD

REPRESENTATIVE LOADS SHOWN FOR ø5m TBM AT 4 bar MAXIMUM PRESURE

NET

800tC’ HEAD

TORQUE2500t

SKIN DRAG TBM WEIGHT90t

SEAL DRAG

TOWING

FORCE

80t

SEAL DRAG

JACKING FORCE

2500t INSTALLED

SKIN DRAG = 400t

TBM

WEIGHT190t

EARTH + WATER

PRESSURE

POSSIBLE SURFACE LOADS(BUILDING, OTHER STRUCTURES)


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SHIELD BODIES

• HIGHLY LOADED STRUCTURAL ELEMENTS

• LARGE AND HEAVY PIECES

• CAN BE SPLIT TO SIMPLIFY TRANSPORT AND ASSEMBLY


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Cutter main seal

Grease purge line

Drive pinion

Grease cavity

Cutterhead support

Forward shield body

Cutter chamber (Soil & Water

Cutter drive unit

Bearing housing

Main bearing

Lubricant cavity

Coolant cavity

Cutter drum

CUTTERHEAD DRIVE STRUCTURE

Main Seals : 4 lip seal x 3 sets / ( inside +outside )

Sealing Pressure : 1.0 MPa

Lubrication : Automatic grease lubricationsystem

Cooling: Water cooled


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Bull gear

Inner race

Roller

Retainer

Seal

A

A

VIEW A

Bull gear

Inner race

Outer race

Roller

Retainer

Seal

A

A

- A

Main Bearing must have extreme capacity to sustain very

high loading and provide necessary reliability

THRUST


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drive type ELECTRICAL MOTOR HYDRAULIC MOTOR

Summary 1.High total efficiency, 90-95%

2. Little maintenance

3. Larger space is necessary forinstallation.

4. Speed control needs additionaldevice (VFD, pole change, etc.).

1. Low efficiency, 65%

2. High maintenance is required foroil contamination, temperature,leakage, etc.

3. Smaller space is necessary forinstallation.

4. Speed control is easy.

CUTTERHEAD DRIVE SYSTEM


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CHS torque

CHS torque is calculated from experimental formula.

CHS torque : T (kNm) = a x D^3

D : shield diameter (m)

a : torque coefficient (- )

(alpha – value)

In case of EPB,

“a” is selected between (20-25).

in case of slurry, (15-20).

0

5000

10000

15000

20000

25000

30000

35000

0 2000 4000 6000 8000 10000 12000 14000 16000

shield diameter (mm)

rotary torque (kNm)Installed cutter drive torque data (EPB)

CUTTERHEAD TYPES


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CUTTERHEAD TYPES

1. OPEN SPOKE TYPE CUTTERHEAD

Spoke type cutterhead

1. opening ratio --- approx. 55%

2. mainly applied for

stable geology, or soft geology


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Agitating bar (fixed)

Agitating bar (rotating)

Cutter head Opening ratio ; 55%

High torque; α=22.3

Protection of soil clogging

High thrust 32,000kN

Soil mixture / conditioning

Foam injection

Speed: 1.5min-1

Fish tail

OPEN SPOKE TYPE CUTTERHEAD

CUTTERHEAD TYPES


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Plate type cutterhead

1. opening ratio --- approx. 30-35%

2. mainly applied for

unstable geology, or mixed (hard)

geology ,or large gravel geelogy

CUTTERHEAD TYPES

2. PLATE TYPE CUTTERHEAD

Additive injection port

Water injection


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2. PLATE TYPE CUTTERHEAD

Agitating bar (fixed)

2 positions

Agitating bar (rotating)

3 positions

Cutter head Opening ratio :29%~60%

High torque: α=29.8

Protection of soil clogging

High thrust: 1500 – 8000 t

Soil mixture / conditioning

Foam injection

5 - 10 positions

Speed: 0-1.5-3.0 rpm


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CUTTERHEAD

• bolt-on type cutter bitpin type cutters bit

welded type cutter bit

fish tail (center cutter)

cutter bit pilot bit(for soil) knife edge bit

special knife edge bit

side protection bit

flapper protection bit

wear detector bit

disc cutter single disc

(for rock) twin (double) disc

(1) Cutting tools


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Pin type cutter bit Functions

1. cutting

2. scraping soil into chamber

SOFT GROUND CUTTING TOOLS


29/94

Bolt on type

cutter bit

Bolt on type

cutter bit



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Special knife edge bit



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Side protection bit

Pilot bitKnife edge bit



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Flapper protection bit

Wear detector

(hydraulic type)Fish tail (center cutter for soil)

H

Hydraulic piping



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(2) Copy cutter

Copy cutter is installed in cutter spoke,

and is hydraulically extended andretracted during rotation..Copy cutter is used to excavate outer

area of cutter head in order to make

curve excavation easy.

copy cutter

spoke

extended and retracted during rotation

CUTTERHEAD

Overcut area



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Single disc, back loading Twin disc, back loading

DISC CUTTERS FOR ROCK, BOULDER, MIXED FACE

EXCAVATION

CUTTERS SEEN FROM INSIDE CUTTERHEAD STRUCTURE

MIXED FACE CUTTERHEAD WITH DISC CUTTERS


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MIXED FACE CUTTERHEAD WITH DISC CUTTERSAssembled Cutterhead view

6.26m EPB for Chengdu metro, china


36/94

Cutter bit material & wear

It is necessary to estimate cutter wear and make a proper plan of cutter bit replacement.

MATERIALS

chip --- tungsten carbide (WC) + cobalt (Co),

hardness : Hv 1000-1100 level (JIS E5)

shank ---SCM440H(JIS),Q345(GB), 42CrMo(EN),etc.

WEAR LIFE , estimationwear : a (mm) = K (wear coefficient) x L (travelling length)

wear coefficient K, (mm/km) , in case of EPB based on chip material of E5

for clay/silt K = 0.005-0.015, ave. 0.010

sand K = 0.015-0.025, ave. 0.020

gravel K = 0.025-0.040, ave. 0.033

travel length L (km) = pai x De/1000 x N x (Lo / V x 1000000 ), at most outside cutter bit

De : excavation diameter (m)

N : cutterhead rotary speed (rpm)

Lo : tunnel length (km)

V : advance speed (mm/min)

shank

chip

CUTTER BIT

(brazing)

Hard facing


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38/94

Cutterhead diameter

Cutterhead diameter is decided to overcut a shield diameter a little larger .

CUTTING DIAMETER OF CUTTER HEAD

Basically, cutting diameter has to be always larger than

shield diameter.

Generally, it is designed as follows.

In case of soil excavation,

Cutting diameter (at outside cutter bit )

De = Ds + 2 x (15-20) mm (for 6-10 m class EPB)

In case of rock excavation,

Cutting diameter (gage disc cutter )

De = Ds + 2 x (25-30) mm (for 6-10 m class EPB)

De Ds

CUTTERHEAD SHIELD


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SHIELD THRUST JACKS

• MUST PROVIDE NEEDED THRUST, PLUS RESERVE

• MUST SAFELY HOLD SEGMENTS DURING RING BUILD• CAN PROVIDE SOME TORQUE REACTION

• MUST BE COMPATIBLE WITH SEGMENT RING DESIGN: KEY INSERTION, KEY

LOCATIONS, RING ROTATION, SEGMENT JOINT LOCATION

• MUST SPREAD LOAD EVENLY TO SEGMENTS TO PREVENT DAMAGE

• MUST HAVE ADEQUATE STROKE FOR RING BUILD, REBOUND, STEERING


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SHIELD THRUST JACKS

THRUST JACKS AND JACKING SHOES MUSTBE COMPATIBLE WITH SEGMENTS

Segment gasket groove too close to edge; no reinforcement.

Crack


41/94

Shield thrust

Shield thrust is calculated from experimental data, geological condition, etc.

Thrust depends on geology, earth

pressure, water pressure, shield

advance speed, etc.

Generally in case of EPB,

Unit thrust (F) is selected ;

F=1100-1200kN/m2

(in case of slurry, 1000-1100kN/m2)

0

200

400

600

800

1000

1200

1400

1600

1800

0 2000 4000 6000 8000 10000 12000 14000 16000

shield diameter (mm)

unit thrust (kN/m2) Installed unit thrust data (EPB)


42/94

2 Chamber

Main chamber

Sub chamber

MAN LOCK

S G C O


43/94

Support jack A

Lift jack

Slide jack Support jack B

Hydro. Motor

SEGMENT ERECTOR


44/94

SEGMENT ERECTOR – MECHANICAL PICKUP


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SEGMENT ERECTOR – VACUUM PICKUP

5 SCREW CONVEYOR


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5. SCREW CONVEYOR

•MAINTAINS PRESSURE IN CUTTER CHAMBER•PRESSURE DROP PROPORTIONAL TO NUMBER OF PITCHES AND SCREW TYPE•VOLUME / PRESSURE CONTROL AT DISCHARGE VIA GUILLOTINE GATE, ROTARY DISCHARGE VALVE,PISTON DISCHARGER ETC.•SCREW SIZE DETERMINES POSSIBLE RATE OF ADVANCE•SCREW SIZE LIMITED BY BEARING / DRIVE ASSEMBLY AND OTHER MECHANICAL ELEMENTS

ONEPITCH

SCREW CONVEYOR


47/94

SCREW CONVEYOR

screw conveyor with shaft

screw conveyor with ribbon screw

hydraulic motor (direct drive)

screw gate (bottom)

inspectionwindow

Screw

blade

screw

casing

screw

shaft

ribbon screw

(1) Screw conveyor type

screw gate (back

end)

hydraulic motor (outside drive)


48/94

Photos of screw conveyor

SHAFT TYPE SCREW CONVEYOR RIBBON SCREW


49/94

SCREW CONVEYOR – RIBBON TYPE

WEAR PROTECTION ACCORDING TO GEOLOGICAL CONDITIONS


50/94

Pressure drop along screw length

earth pressure P1

screw gate

Screw length

P1=0

soil

Pressure drop ; delta P=0.02 to 0.03 Mpa/pitch

screw conveyor length L

ADJUST ROTARY SPEED, DISCHARGEOPENING, AND ADDITIVES TO CONTROLPRESSURE DROP

SCREW CONVEYOR – RIBBON TYPE


51/94

HIGH TORQUE DRIVE SYSTEM


52/94

screw conveyor

R/G

O/M

R/G

O/

M

R/G

O/M

SHAFT TYPE SCREW CONVEYOR,

normal type

RIBBON TYPE SCREW CONVEYOR,

In case of large gravel with low pressure

MIXED TYPE SCREW CONVEYOR,In case of large gravel with high pressure

screw with shaft

casing

casing

casing

gate

gate

gate

ribbon screw

screw with shaftribbon screwinspection window

∆P

BOULDERDISCHARGE

APPROX 0.2 BARPER FLIGHT


53/94

screw conveyor numbers

No2 screw

No1 screwNo1 screw

gategate

SINGLE SCREW CONVEOYR DOUBLE SCREW CONVEOYR

spherical joint

Applications

1. in case of high earth pressure geology,

2. in case of non-belt conveyor transportation applied,

MIXED TYPE SCREW CONVEYOR


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DISCHARGE

MIXED TYPE CONVEYOR


55/94

MIDGUILLOTINEGATE

MIXED TYPE CONVEYOR



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INSPECTION DOORFOR LARGEBOULDER REMOVAL

ACCESS DOOR

FOR BOULDERREMOVAL BOX

6 ARTICULATION SYSTEM


57/94

Articulation seal Articulation jack

Front shield Rear shield

6. ARTICULATION SYSTEM


58/94

rticulation for Curved Tunnels


59/94

ARTICULATION

Thrust cylinders are installed on front shield.

PASSIVE ARTICULATIONACTIVE ARTICULATION

Thrust cylinders are installed on rear shield

in parallel direction. Articulation cylinders connect front- and rear

shields.

SKID EFFECTb

a a

Fa

Fa F in

F out

Thrust cylinders are installed on front shield.

Articulation cylinders connect front- and rear shields.

・Steering is easier.・Thrust cylinders push segment ring evenly,

which reduces segment damage.(segment preferably receives even thrust loads.)

・Articulation force is approx. 70-80% of thrust.

・Steering is harder.Thrust cylinders push segment ring unevenly.(segment receives partial thrust loads.)Articulation force is approx. 50% of thrust.(cylinder cot is low)


60/94

Rear push type

F

No tail clearance –difficult to assemble segments

Inside cylinder(s), not be pushed.

Inclined cylinder angle to segment

Small steering moment

F

Large steering moment

Tail clearance is even.

Pushing paralell to segment

Front push type

(curve direction)

d

d

(curve direction)

Segment moves outside.

TYPE OF ARTICULATION


61/94

Front shield

Rear shield

Rear shieldFront shield

Passive Articulation system

Active Articulation system

Thrust cylinder. pushes the front

shield.

Articulation cylinder. pushes the

front shield.

TYPE OF ARTICULATION

TAIL SEAL


62/94

(1) Automatic tail seal lubrication system controlling order, time, volume

(2) Every annual space between tail seal having injection ports

Annual Space Tail seal (Brush type) , 3 rows

Lubrication line for each space

Segment

Tail skin plate

TAIL SEAL

CRITICAL TO PREVENT GROUNDWATER OF GROUT FROMINFILTRATING SHIELD BODY

BRUSH TYPE SEALS AND THICK GREASE MAKE SEAL

TAIL SEALGREASE


63/94

SEGMENT

4-2-1 shield (skin plate)

(1) how to decide shield diameter

Tail skin plate

SEGMENT

Tail skin plate thickness : t

Segment outside diameter : DsShield outside diameter : Db

Tail clearance : x

Tail clearance and skin plate thickness should be properly selected in order to reduce tail void and backfill grouting for bettersurface stability and economy.

Shield O.D ; Db = segment outside diameter(Ds) + 2 x (tail clearance(x) + skin plate thickness(t) )

normal tail clearance ; x = 25mm, for 4- 6m class EPB, normal skin plate thickness ; t =60-100mm= 40mm, for 9-10m class EPB, (depending on strength, backfill piping design, etc.)

(backfill piping of approx. 40mm, others)

Tail seal (25-28mm)

BACKFILL GROUT COST

APPROX $200/m3BACKFILL ANNULUS VOLUME

7 BACKFILL


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7. BACKFILL

To fill the circular gap between shield and segment perfectly is very important for surface stability and

segment fixing.

backfill groutingbackfill injection device

SEGMENT

CUTTER HEAD segment diameter dshield diameter D

tail void

backfill theoretical volume (tail void): Q = pai * (D^2 - d^2 ) / 4 x length

Normally, backfill grouting device has 130% injection ratio ( = injection volume / tail void x 100 (%) )

Two kinds of injection control method are available --- (1) volume control and (2) pressure control.

GL

SHIELD

One liquid (mortar) and two liquid grouting


65/94

There are two types of backfill grouting---one liquid type and two liquid type

.

Schematic / one liquid type

reciever tank

M

SEGMENT SEGMENT

back fill devicepower board

back fill device

control board

back fill device

control panel

back fill device

control panel x x

x x

flushing line

mortar pump

mortar tank

TAIL VOIDTAIL SKIN PLATE


66/94

Comparision


67/94

one liquid (mortar) and two liquid grouting

Item One liquid (mortar) Grouting Two liquid Grouting

(1) Strength More than 20Mpa can be achieved(28days)

◎ 2-3Mpa (28 days) ○

(2) Usable time(After

batching)

Less than 12 hours ○ More than 24 hours (A liquid) ◎

(3) Gel time Difficult to control △ 20 sec or less, 1 hour or later can be rheologic.

○

(4) Setting Time Very long, very difficult to stabilizelining, easy to occur segment gap,flotation.

× 1 hour or later, can hold liningeffectively

◎

(5) Volume Loss Depend on filling condition, lessthan 3%

◎ Very little, less than 5% ○

(6) Segregation Easy to segregate with undergroundwater

△ No segregation ◎

(7) Fillingness Poor with low pressure, partialpressure on lining, with groundwater cause flotation force.

× Very well with low pressure,provide unique pressure onlining

◎

Comparison table Mortar grouting and Two-liquid grouting


68/94

(8) Ring Steppingand floatation

Easy to happen stepping on lining joint,Floatation is also easy to happen.

△ Minor stepping evident butgenerally good tunnel.

○

(9) Grouttransportation

Cement mortar grout delivered byoutside batching plant and hencedelivery to be managed.Grout loading and transport required intunnel. Transfer required on TBM fromgrout car to front tank with extrablockage risk.

△ Mixing at surface and delivered bypressured pipe line toNo delivery time risk (Sunday, Nightshift) as the material delivery canbe managed during normal hours

◎

(10) Cleanup Extensive cleanup of grout car, transfer pump, transfer line, grout tank on trailer 1 and grout pumps.

△ Reduced cleanup.Line cleaning twice daily for “type A” line using pig.

◎

(11) Grout mixingquality

Grout delivery variability by supplier, onsite plant also not easy to control.

Mixing with manual control pump is notuniform.

△ Mixing procedure controlled bycomputer system.

Uniform quality no breaching.

◎

(12) On sitehandling

Labor intensive relatively for transfersand manual recording

× No manual mix control operationrequired.Computerized operation Automaticrecord (volume, pressure, time etc)

◎


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(13) Grouting portGrout pump

Normally required more than 4nos, 2pump. Depend on TBM diameter △

Normally required 2nos, 1 pump.Depend on TBM diameter. ◎

(14) Loss time risk Mixing nozzle blockage problemsolved with mix change

△ Mixing nozzle blockage mayhappen

○

(15) Trouble record Many trouble record reported △ No trouble report more than 25years

◎

(16) Materialavailability

Depend on the country, necessarymaterial is not easy to get withstandard quality.

△ Any country necessary material iseasy to get with standard quality.

◎

(ref) TAC*1 two liquid system


70/94

( ) q y

two liquid type, located outside of tail shieldheight is approx. 100mm (incl. cover plate.)

Hydraulic cylinder

A liquid lineB liquid line

flushing line

Mixing nozzle

*1 ---- Japanese backfill device supplier


71/94

TAC backfill grouting systemOperation details

清掃ジャッキ縮

裏込材

地山

A liquid line

B liquid line

Flushing line

B liquid line

Mixing nozzle

Piston, operated by hydrauliccylinder

清掃ジャッキ伸

洗浄液

地山

A liquid line

B liquid line

Flushing line

Backfill injection

Line flushing

Backfill injection


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8. ADDITIVES

• Generally speaking, excavated soil cannot transmit earth pressure evenly and properlyas it has not sufficient fluidity.

• Therefore, it is necessary to inject additives (foam or bentonite, others) so as to improvesoil fluidity.

• Improved soil makes it possible to keep accurate and even earth pressure in muckchamber, and also easier transportation through screw conveyor while reducing earth

pressure inside of screw conveyor.

bentonite Additive type

foam

Each additive has each calculation method according to actual geological conditions.

Effect of foam injection


73/94

Injection 10% Injection 15% Injection 20%

Injection 25% Injection 30% Injection 40%

(2) Foam injection


74/94

Injection port

FEATURE OF FOAM INJECTION

1. Foam can reduce stickness of soils,

which will bring smooth soil movement and

less cutter head and screw rotary torque.

2. Foam can improve muck fluidity of wide

range of soils with high sealing performance.

3. Foam , as air characteristics, has a

damper effect of earth pressure.

4. Foam disappears in some period of time,

which makes it easy to handle muck

disposal.

5. Foam device is compact.

clay 35% (to reduce stickness)silt 20%

sand 30%

gravel 65%(to increase fluidity)

Arrangement of foam injection port (sample)

Emisor 8.89m EPB , 12 ports applied

(2) Foam injection


75/94

M

Additive tank Water tankAir Compressor

Mixing tank

Foam Generator

Foam Generator

Foam Generator

FOAM GENERATION



76/94

Improve the fluidity of excavated muck by thebearing efficiency of foam.

Improve the waterproof of excavated muck byreplacing the water by foam between soil grains.

Prevent the sticking of excavated muck oncutterhead and chamber.

Improve the working environment.


9. EPB OPERATION FLOW CHARTEPB EXCAVATION CONTROL


77/94

EPB EXCAVATION CONTROL

NOTES

P0 ; target earth pressure for excavation

P1 ; actual earth pressure

CALCULATION OF THEORITICAL EARTH PRESSURE

SETTING OF EARTH PRESSURE P0

SETTING OF THRUST CYLINDER SPEED AND

SCREW CONVEYOR ROTARY SPEED

EXCAVATION

EARTH PRESSURE

P1

CUTTERHEAD

TORQUE

DECREASING SCREW SPEED,

INCREASING ADVANCE SPEED

INCREASING SCREW SPEED,

DECREASING ADVANCE SPEED

P1>P0 P1


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79/94

MUCK HAULAGE FOR EPB TUNNELS

RUBBER TIRE VEHICLES

• CYCLIC

• USEFUL FOR STEEP GRADES

• FEASIBLE FOR SHORT TUNNELS

• FEASIBLE FOR LARGER TUNELS WHERE AROADWAY IS BEING CONSTRUCTEDSIMULTANEOUSLY AND THERE IS ROOM FORTRUCKS TO PASS

• DIESEL POWER REQUIRES EXTRA VENTILATION

• USEFUL TO HAUL IN SEGMENTS AND OTHER

MATERIALS


80/94


RUBBER TIRE VEHICLES


81/94


MINE TRAIN HAULAGE

• CYCLIC

• LIMITED TO 2-4% GRADE MAXIMUM

• CAN GENERALY PASS TRAINS IN SMALLTUNNELS. CAN BE SUITABLE FOR LONGTUNNELS WITH SWITCHES

• DIESEL POWER REQUIRES EXTRA VENTILATION• USEFUL TO HAVE IN SEGMENTS AND OTHER

MATERIALS


82/94


83/94


MUCK CAR HAULAGE

TAMPA WATER PROJECTAlafia River Crossing

ROBBINS EPB TBM SS84-302

Muck improved by injecting additives

• Bentonite

• Polymers

• Large quantities of additives

were required


84/94


PUMPING AND SLURRY SYSTEMS

• CONTINUOUS SYSTEM (EXCEPT DURING PIPE

ELONGATION)

• USEFUL FOR STEEP GRADES, UP SHAFTS

• CAN CONTAIN HIGH WATER FLOWS AND H2S

OR OTHER GASSES LIBERATED AT THE FACE• CLEAN


85/94





Grizzly hopper at screw

conveyor discharge


86/94





Slurry pump at shaft bottom



87/94


CONTINUOUS CONVEYOR SYSTEM

• CONTINUOUS SYSTEM

• RAPID PRODUCTION RATES

• USEFUL FOR STEEP GRADES (STEEPER THANRAIL HAULAGE)

• GRADE LIMITED BY MATERIAL CONSISTANCY,

WATER • REDUCED DIESEL FUMES, TUNNEL

VENTILATION REQUIREMENTS ARE REDUCED.



88/94





89/94



• Lower NW Interceptor (LNWI)

• 4.6 m (15 ft) EPB

• Two 610 m (2000 ft) rivercrossings at 6% downgrade

• First soft ground TBM tunnel

with continuous conveyor



90/94



• Specially designed continuousconveyor with sealed transferpoints and conveyor wash box



91/94



Vertical storage



92/94


Conveyed Material




93/94


Wash Box



94/94

END OF PRESENTATION

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EPB Short Course 2010

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