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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
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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
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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)
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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,
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Slurry shield
6.5m slurry 7.45m slurry
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EPB shield
9.98m EPB 6.26m EPB
6.14m EPB 15.01m EPB
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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
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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
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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
○
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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
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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
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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
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Bolt on type
cutter bit
Bolt on type
cutter bit
SOFT GROUND CUTTING TOOLS
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Special knife edge bit
SOFT GROUND CUTTING TOOLS
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Side protection bit
Pilot bitKnife edge bit
SOFT GROUND CUTTING TOOLS
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Flapper protection bit
Wear detector
(hydraulic type)Fish tail (center cutter for soil)
H
Hydraulic piping
SOFT GROUND CUTTING TOOLS
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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
SOFT GROUND CUTTING TOOLS
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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
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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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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
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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)
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2 Chamber
Main chamber
Sub chamber
MAN LOCK
S G C O
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Support jack A
Lift jack
Slide jack Support jack B
Hydro. Motor
SEGMENT ERECTOR
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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
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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)
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Photos of screw conveyor
SHAFT TYPE SCREW CONVEYOR RIBBON SCREW
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SCREW CONVEYOR – RIBBON TYPE
WEAR PROTECTION ACCORDING TO GEOLOGICAL CONDITIONS
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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
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HIGH TORQUE DRIVE SYSTEM
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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
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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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MIXED TYPE SCREW CONVEYOR
DISCHARGE
MIXED TYPE CONVEYOR
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MIDGUILLOTINEGATE
MIXED TYPE CONVEYOR
MIXED TYPE SCREW CONVEYOR
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MIXED TYPE SCREW CONVEYOR
INSPECTION DOORFOR LARGEBOULDER REMOVAL
ACCESS DOOR
FOR BOULDERREMOVAL BOX
6 ARTICULATION SYSTEM
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Articulation seal Articulation jack
Front shield Rear shield
6. ARTICULATION SYSTEM
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rticulation for Curved Tunnels
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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)
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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
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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
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(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
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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
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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
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Comparision
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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
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(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
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( ) 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
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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
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Injection 10% Injection 15% Injection 20%
Injection 25% Injection 30% Injection 40%
(2) Foam injection
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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
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M
Additive tank Water tankAir Compressor
Mixing tank
Foam Generator
Foam Generator
Foam Generator
FOAM GENERATION
FEATURE OF FOAM INJECTION
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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.
FEATURE OF FOAM INJECTION
9. EPB OPERATION FLOW CHARTEPB EXCAVATION CONTROL
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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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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
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MUCK HAULAGE FOR EPB TUNNELS
RUBBER TIRE VEHICLES
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MUCK HAULAGE FOR EPB TUNNELS
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
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MUCK HAULAGE FOR EPB TUNNELS
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
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MUCK HAULAGE FOR EPB TUNNELS
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
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MUCK HAULAGE FOR EPB TUNNELS
PUMPING AND SLURRY SYSTEMS
TAMPA WATER PROJECTAlafia River Crossing
ROBBINS EPB TBM SS84-302
Grizzly hopper at screw
conveyor discharge
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MUCK HAULAGE FOR EPB TUNNELS
PUMPING AND SLURRY SYSTEMS
TAMPA WATER PROJECTAlafia River Crossing
ROBBINS EPB TBM SS84-302
Slurry pump at shaft bottom
MUCK HAULAGE FOR EPB TUNNELS
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MUCK HAULAGE FOR EPB TUNNELS
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.
MUCK HAULAGE FOR EPB TUNNELS
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MUCK HAULAGE FOR EPB TUNNELS
CONTINUOUS CONVEYOR SYSTEM
MUCK HAULAGE FOR EPB TUNNELS
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MUCK HAULAGE FOR EPB TUNNELS
CONTINUOUS CONVEYOR SYSTEM
• 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
MUCK HAULAGE FOR EPB TUNNELS
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MUCK HAULAGE FOR EPB TUNNELS
CONTINUOUS CONVEYOR SYSTEM
• Specially designed continuousconveyor with sealed transferpoints and conveyor wash box
MUCK HAULAGE FOR EPB TUNNELS
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MUCK HAULAGE FOR EPB TUNNELS
CONTINUOUS CONVEYOR SYSTEM
Vertical storage
MUCK HAULAGE FOR EPB TUNNELS
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CONTINUOUS CONVEYOR SYSTEM
Conveyed Material
MUCK HAULAGE FOR EPB TUNNELS
MUCK HAULAGE FOR EPB TUNNELS
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CONTINUOUS CONVEYOR SYSTEM
Wash Box
MUCK HAULAGE FOR EPB TUNNELS
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END OF PRESENTATION