TBM DESIGN AND SELECTION
10 2 66 ครัง้ ที่ 4
TERRATEC Education Program
1. TBM CATEGORY IN GENERAL
SHIELD MACHINE TYPE IN SOIL
• EPB TBM
• SLURRY TBM
SHIELD MACHINE TYPE IN ROCK (FUTURE DISCUSSION)
• SINGLE SHIELD TBM
• DOUBLE SHIELD TBM
|
หัวเอา
In,
Shield Machine Type in SOIL
EPB
Type
SLURRY
Pressure
Control
Geology
By Muck (Solid)
By SLURRY (Liquid)
Through Screw
conveyor
Through Slurry pump
Both Available for all Geological Condition
Advance Unit
Shield Jack
Shield Jack
Merit
For Restricted
Space
Under High Pressure
กว่ าเพราะมี ดูคนาโคลน
แพง
ROCK (future discussion)
Type
SINGLE SHIELD
DOUBLE SHIELD
Pressure
Control
Not require
Not require
Geology
Poor Rock
Good Rock
Advance Unit
Shield Jack
Shield Jack &
Gripper
Merit
Good for all rock
situation
Excellent advance
rate
Shield Machine Type in SOIL
Type
Pressure Control
Geology
EPB
SLURRY
By Muck (Solid)
By SLURRY (Liquid)
Through Screw conveyor
Through Slurry pump
Both Available for all Geological Condition
Advance Unit
Shield Jack
Shield Jack
Merit
For Restricted Space
Under High Pressure
Apply Ratio
80%
20％
Total Cost
Reasonable
Expensive (Facilities)
Shield Machine Type in ROCK (future discussion)
Type
SINGLE SHIELD
DOUBLE SHIELD
Pressure Control
Not require
Not require
Geology
Poor Rock
Good Rock
Advance Unit
Shield Jack
Shield Jack & Gripper
Merit
Good for all rock situation
Excellent advance rate
2. TBM SELECTION AND DESIGN CONDITION
FEATURES
ISSUE
Sectional Shape & Dimension
Type and characteristics of sectional shapes
Cutter head and cutter bit wearing
Tunnel Length
Overburden
Tunnel Alignment
Main bearing seal durability
Shallow tunnel - ground collapse, underground obstruct
Deep tunnel - resist high water pressure
Tight curve need articulation and copy cutter device
Special articulation design needed.
Existing structure in ground
Obstacles
Design cutter bit
Geotechnical Condition
Soil / rock and engineering characteristic
Site Condition and location
Site location and shaft dimension
SECTIONAL SHAPE & DIMENSION
•
TYPE AND CHARACTERISTICS OF SECTIONAL SHAPES
SECTIONAL SHAPE & DIMENSION
•
GENERAL TERRATEC & JIMT TBM
✓ 0.6m~over 16m Size, Various Type of Machine Design & Manufacturing
✓ Delivered over 4,000 machines in Japan and over 400 machines for overseas
2. TBM SELECTION AND DESIGN CONDITION
FEATURES
ISSUE
Sectional Shape & Dimension
Type and characteristics of sectional shapes
Tunnel Length
Overburden
Tunnel Alignment
Obstacles
Cutter head and cutter bit wearing
Main bearing seal durability
Shallow tunnel - ground collapse, underground obstruct
Deep tunnel - resist high water pressure
Tight curve need articulation and copy cutter device
Special articulation design needed.
Existing structure in ground
Design cutter bit
Geotechnical Condition
Soil / rock and engineering characteristic
Site Condition and location
Site location and shaft dimension
TUNNEL LENGTH
•
Long distance tunnel
• The tunnel section longer than 1.5km is referred as long tunnel.
• Cutter Bit : Wear and damage calculate based on soil condition and
driving distance, material and bit arrangement.
Cutter bit wearing and damage after 5-kilometer drive.
•
Long distance tunnel
• Cutter head; wearing depends on soil condition, rotation speed, Hard
facing material, additional abrasive steel.
Q
Cutter Head wearing and copy cutter wearing
nosimumston
TUNNEL LENGTH
• Long distance tunnel
• Main Bearing seal; seal protect the bearing (TBM’s heart – most
important part) must withstand the heat and pressure.
Terratec TBM has a unique design, so far so good.
Shield Body & Bearing Housing
(No Rotate)
Outer Sealing
CutterHead
(Rotate)
Inner Sealing
Drive Motor & GearBox (No Rotate)
2. TBM SELECTION AND DESIGN CONDITION
FEATURES
ISSUE
Sectional Shape & Dimension
Type and characteristics of sectional shapes
Tunnel Length
Overburden
Tunnel Alignment
Obstacles
Cutter head and cutter bit wearing
Main bearing seal durability
Shallow tunnel - ground collapse, underground obstruct
Deep tunnel - resist high water pressure
Tight curve need articulation and copy cutter device
Special articulation design needed.
Existing structure in ground
Design cutter bit
Geotechnical Condition
Soil / rock and engineering characteristic
Site Condition and location
Site location and shaft dimension
OVERBURDEN
•
Rule of thumb, minimum overburden is 1.0-1.5D. But it often decided based
on the intended propose and obstacle existing structure.
•
Shallow, to consider ground collapse, leakage of slurry & backfill grout to
ground surface. Encounter with underground obstructed. Uplift to be examine
if the tunnel runs below groundwater level or under the sea.
Yokohama North Line, 10.83m Diameter
Bangkok Orange Line, 6.39m Diameter
OVERBURDEN
•
Deep tunnel to design to resist high water pressure - high thrust force, seal
performance) and high risk of flooding
2. TBM SELECTION AND DESIGN CONDITION
FEATURES
ISSUE
Sectional Shape & Dimension
Type and characteristics of sectional shapes
Tunnel Length
Overburden
Tunnel Alignment
Obstacles
Cutter head and cutter bit wearing
Main bearing seal durability
Shallow tunnel - ground collapse, underground obstruct
Deep tunnel - resist high water pressure
Tight curve need articulation and copy cutter device
Special articulation design needed.
Existing structure in ground
Design cutter bit
Geotechnical Condition
Soil / rock and engineering characteristic
Site Condition and location
Site location and shaft dimension
TUNNEL ALIGNMENT (CURVE RADIUS, GRADIENT)
•
•
•
Ordinary horizontal curve radius can be excavated without articulation shield.
Sharp horizontal curves need articulation unit, copy cutting device. Special
articulation seal design needed.
Large gradient need heavily considering the segment and muck transportation
as well as drainage system.
Special Horizontal Articulation
Special Vertical Articulation
Shallow Overburden 1.3m, 7.6% steep slope, Tight radius 50m
MSV (Multi Service Vehicle) in
10.4m tunnel
Tight curve radius tunnel
Very steep slope
Parallel tunnel, more pressure created from adjacent tunnel.
Bracing inside the adjacent tunnel
2. TBM SELECTION AND DESIGN CONDITION
FEATURES
ISSUE
Sectional Shape & Dimension
Type and characteristics of sectional shapes
Tunnel Length
Overburden
Tunnel Alignment
Obstacles
Cutter head and cutter bit wearing
Main bearing seal durability
Shallow tunnel - ground collapse, underground obstruct
Deep tunnel - resist high water pressure
Tight curve need articulation and copy cutter device
Special articulation design needed.
Existing structure in ground
Design cutter bit
Geotechnical Condition
Soil / rock and engineering characteristic
Site Condition and location
Site location and shaft dimension
OBSTACLES
•
•
Surface & underground structure, Underground utilities, Existing and old well,
Remained building and temporary construction.
Either remove from ground surface or remove from the face of the shield
need to be planed in advance.
Face intervention to remove the pile
Underpinning
OBSTACLES
•
Direct cut using cutter bit; the
machine can be designed to cut the
steel bar, sheet pile, reinforce
concrete etc.
•
Direct cut using cutter bit; the machine can be designed to cut the
steel bar, sheet pile, reinforce concrete etc.
•
Special Design Cutter head and cutter bit.
Our Experience
2. TBM SELECTION AND DESIGN CONDITION
FEATURES
ISSUE
Sectional Shape & Dimension
Type and characteristics of sectional shapes
Cutter head and cutter bit wearing
Tunnel Length
Overburden
Tunnel Alignment
Main bearing seal durability
Shallow tunnel - ground collapse, underground obstruct
Deep tunnel - resist high water pressure
Tight curve need articulation and copy cutter device
Obstacles
Special articulation design needed.
Existing structure in ground
Design cutter bit
Geotechnical Condition
Soil / rock and engineering characteristic
Site Condition and location
Site location and shaft dimension
GEOTECHNICAL CONDITION
•
•
•
Soil/Rock profile
Engineering characteristic (strength, abressivity, permeability)
Underground water, fault zone, Shear zone.
GEOTECHNICAL analysis
+190m
Upper Clastics
+70m
Upper Salt
+40m
Middle Clastics
GEOTECHNICAL analysis
•
Engineering characteristic (Thickness, Unit weight, Fissures/Fractures,
Strength)
Intentionally blank page for the solution
Sample soil profile in Bangkok
Sample Rock profile in Changmai
2. TBM SELECTION AND DESIGN CONDITION
FEATURES
ISSUE
Sectional Shape & Dimension
Type and characteristics of sectional shapes
Tunnel Length
Overburden
Tunnel Alignment
Obstacles
Cutter head and cutter bit wearing
Main bearing seal durability
Shallow tunnel - ground collapse, underground obstruct
Deep tunnel - resist high water pressure
Tight curve need articulation and copy cutter device
Special articulation design needed.
Existing structure in ground
Design cutter bit
Geotechnical Condition
Soil / rock and engineering characteristic
Site Condition and location
Site location and shaft dimension
SITE CONDITION AND LOCATION
•
•
•
•
Site utilization plan and site access
Launch shaft and receiving shaft dimension
TBM assembly and disassembly procedure
Planning at Intermediate shaft for maintenance (cutter intervention)
Launch and arrival shaft dimension restriction
• Space for TBM assembly and disassembly
TBM arrival at various condition
Cutter intervention at intermediate
shaft
•
Cutter bit can be inspected and
replace when long distance
excavation or after obstruct cutting.
3. EPB & Slurry Shield concept
3.1 EPB shield
• When TBM is moved forward, the pressure of excavated soil filling the cutter
chamber maintains face stability, and excavated soil is discharged via a screw
conveyor. The pressure of the cutter chamber control by the revolution speed
of screw conveyor and advance rate of the shield.
• An appropriate plastic flow and the impermeability for the excavated soil is
needed. Additive injection such as foam and polymer are used to mix with the
soil to maintain it plasticity.
EPB MUCK TRANSPORTATION
•
By Muck car, the car will be transport out of the tunnel by locomotive.
EPB MUCK TRANSPORTATION
•
By continuous belt conveyor, the muck will transport out by belt to the
dumping ground.
SLURRY SHIELD (little complicate)
•
•
Face is stabilized by slurry pressure which should be balanced by earth/water
pressure.
In sand or gravel with low uniformity coefficient and large coefficient of
permeability, slurry quality, such as specific gravity, viscosity is very important,
otherwise slurry may leak into the ground and the filter cake film may not be
form.
Pressurized
Earth paste
Reduction
Cause by
filtration
SLURRY Blow out!
•
When slurry pressure more than actual earth pressure especially at the
shallow tunnel. Blow out often occurred.
SLURRY TBM OPERATION
•
•
•
•
Slurry feed pump control the slurry flow and pressure at the face.
Density meter and flow meter (inlet & outlet) are tool for operator to control
the face pressure
The discharge slurry always have more density than the feed slurry.
Treatment plant to separate the soil from the thick slurry.
Slurry transportation system
•
•
The treatment plant has a unique technology to separate the soil out
from slurry.
Sand easy and fast separated, Clay & silt more difficult and take time
EPB OR SLURRY?
•
•
•
EPB and Slurry can suit for all soil condition.
When encounter the water pressure;
• EPB assumed as an open mode (screw gate open to release the
face pressure)
• Slurry assumed as closed mode (all the pipes connected from
face to surface, with long distance)
• So, at high pressure ground water pressure, slurry TBM control
better face pressure.
Slurry has huge backup facilities in sum-up expensive.
JAPAN STANDARD FOR THE SELECTION
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4. TBM DESIGN
TBM DESIGN PHOLOSOPHY
• KEY POINT TO CONSIDER BEFORE DESIGN TBM
TBM COMPONENT DESIGN
• TBM GEOMETRY
• CUTTER HEAD/ CUTTER BIT
• ADVANCE UNIT
• SEGMENT ASSEMBLY UNIT
• ARITICULATION AND COPY CUTTER
• TBM BACKUP UNIT
• SOIL CONDITIONING and BACKFILL GROUT
• GREASE STATION
TBM DESIGN PHOLOSOPHY FOR SOIL
N-Value (STP Value)
•
Sometime we refer N-value for the fast understanding the soil properties
Permeability (Soil)
•
•
•
The most important for pressure control.
High permeability is likely to cause the trouble during the construction
such as boulder and coarse sand.
Too stiff or impermeable soil need more water to prevent the clogging.
TBM COMPONENTS DESIGN
TBM GEOMETRY
•
TBM body divided into section need for transportation and assembly.
TBM diameter (D)
•
•
Estimate TBM diameter from segment lining (D0) and tail clearance (x) and
tail skin plate thickness (t).
Tail clearance (x) is an allowances for erecting segment. Calculate from
minimum curve radius.
= /2 or
~ 20-40mm in general
D = 4120mm + 2(30mm+45mm) = 4270mm
Tail clearance (x) is an
allowances for erecting
segment. Segment will never
touch the TBM skin plate.
TBM LENGTH (Lℓ = ℓ + ℓ ) ESTIMATION
• Cutter length (ℓ ) based on structure design varies project by
project. But the best guess is 1000mm. (ℓ = 1000mm)
• Length of shield body (ℓ ) = ℓ + ℓ + ℓ
• ℓ can be estimate by “ℓ /D” chart from Japan standard.
• Hood section (ℓ ) is a space for storage the excavated soil. From
experience this volume around 0.8-1 ring excavation.
• Middle section (ℓ ) is a space for articulation, shield jack, drive
unit and cutter motor.
• Tail section length (ℓ ) roughly estimate by the segment length
and tail seal section.
TBM LENGTH (Lℓ = ℓ + ℓ )
D = 4270mm
ℓ /D ~ 1.7
ℓ = 1.7x4270 = 7259mm
So, Lℓ = 1000 + 7259 = 8259mm
This estimation can be used for project feasibility or early
design stage such as lunch shaft or arrival shaft size
CUTTER HEAD
•
•
Center shaft support type; Simple design, used for small size TBM (Ø2-5m).
Boulder and cobbles can be difficult to handle.
Intermediate support type; used for a bigger size TBM (Ø3-16m). Very strong,
structurally favored. No so good for cohesive soil often clog at the center
section
Type
Geology
Center Shaft Type
Intermediate support
Soil
●
●
Gravel
●
●
●
Boulder
Soft Rock
（●）
●
●
Hard Rock
Application
Machine Dia. 2~5m
Machine Dia. 3~16m
Merit
Compact
Heavy Duty
CUTTER HEAD
•
•
Cutter frame spoke type with more opening ratio suit for soft ground. Cheap
and compacted design.
Cutter frame face type with less opening ratio suit for mix ground and rock.
Heavy duty. More cutter bit can be installed.
φ
φ2
φ4
Φ
φ10
φ15
φ
φ2
Φ
φ8
φ4
φ12
OPENING RATIO
•
•
•
Opening ratio equal to Total opening area (AS) and Total cutter area (AR).
It is 30-40% for flat type and 60-80% for spoke type.
Stiff clay is likely to clog the face with less opening ratio.
•
10-30% for slurry shield
•
30-40% for EPB Frame face type
•
60-80% for EPB spoke type
CUTTER CAPACITY/ CUTTER TORQUE
• Refer to the sample calculation.
T = T1+T2+T3+T4
REQUIRED CUTTER TORQUE
- T1: Cutting Torque, torque from soil cutting.
Shield diameter, TBM speed, Cutter rotation,
penetration depth, and soil strength are the
factors.
- T2: Earth Pressure Friction Torque, There are
two friction torque. From earth pressure acting at
front face and from the earth pressure action at
the side of the cutter.
- T3: Mixing arm Torque, The excavated soil
would be mixed with additives to change the
strength of soil become softer. This resistance
come from cutter spoke, mixing blades and
resistance from cutter support.
- T4: Mechanical Friction Torque: frictions from
reduction gear, bearing and seal.
CUTTER BIT
• Main Bit slice soil to a thin flat piece suit for soft ground.
• Precede Bit cut obstruction temporary wall at launch and
arrival shaft, make a grove line.
• Roller cutter /Disc for crushing rock.
BIT VARIATION AND ADEQUATE SELECTION
Main Bit
Tooth
Precede Bit
Scraper
Condition
Standard
Type
Long Life
Type
Loose
●
Sharpness
Stiff
●
Sharpness
●
Secure
●
●
Secure
●
<40MPa
●
Secure
>40MPa
●
Secure
Obstacle Cutting
●
Secure
Soil
Gravel
Boulder
Rock
Long Span Excavation
●
Secure
Disk Cutter
Special
Type
Composite
Roller
Ring
Roller
●
●
●
●
CUTTER BIT durability
• Bit durability wearing depend on soil type and bit material.
• Tungsten carbide tip has hardness almost 10 time more than normal steel
plate SS400
• The calculation shown 3km drive in sand has an acceptable wearing.
Wear Resist Material Hardness Comparison
Material
Tungsten Carbide Tip
Hard Facing
Disk Roller
Ring
Anti-Wear
Plate
Steel Plate
Hv
HRC
HRA
Remarks
E3 (JIS)
1,250
72
88
Bit
E5 (JIS)
1,000
69
86
Bit
HF-800
736
61
82
Secure
HF-700
654
58
80
Secure
SKD-11
700
60
81
Disk
SKD-61
600
55
79
Disk
SNCM-439
580
54
78
Disk
HALDOX-500
500
49
75
Secure
HALDOX-400
400
40
70
Secure
SKC-24
400
40
70
Bit Shank
S45C
220
18
-
Frame
SS400
180
-
-
Frame
ADVANCE UNIT
• Shield advance unit powers by a number of hydraulic jacks at a high pressure
of 30-40 Mpa. created maximum jack speed (TBM speed) up to 100 mm/min.
• Capacity of thrust force determined by sum of all resisting force against
machine operation plus some factor safety.
Required Thrust Force
- F1: Outer Surface Friction
- F2: Earth and Water Pressure Force (Front)
- F3: Segment Friction Force
- F4: Traction Force
S=2-times
Safety
Factor
Consider Curve Execution
Only one side jack operation case
F=F1+F2+F3+F4+F5
JAPAN STANDARD
• Typical thrust force vs shield diameter for reference. Equipped Thrust Unit
Force (1,000~1,200kN/m2)
• Sample thrust force calculation.
THRUST FORCE for launching
• During TBM launch, friction at TBM
come frame the TBM body and
steel cradle.
• During initial drive, no traction
force for pulling the backup car.
SEGMENT ASSEMBLY (ERECTOR)
• Erector is a simple function just lifting and rotating the segment pieces.
• The lifting force is usually 1.5-2.0 times larger than the segment weight.
• The segment gripping type has 5-6 degree of freedoms.
SEGMENT ASSEMBLY (ERECTOR)
• The segment gripping type has 5-6 degree of freedoms.
ARTICULATION AND COPY CUTTER (ALIGNMENT CONTROL)
• These equipment use when TBM position can not be controlled only by
operation of the shield jack.
• Articulation jack install between the front and rear bodies to bend the bodies.
• The X-type system is more suitable for extremely tight curves at depth and
with high groundwater pressure. This is due to the X-type articulation system’s
spherical structure and also that using a balance of extending and retracting
the articulation jacks provides constant clearance of the articulation seals.
ARTICULATION
• Active articulation keep the shield jack perpendicular to the segment all the
time during the bend.
• Active articulation force = (80-100%) x Shield thrust force.
• For tight curve radius (R<80m), TBM should design for active articulation with
x-type articulation.
COPY CUTTER
• Overcutting devices for overcutting in acutely curved tunnels
should be used to enhance the
operation of the shield machine
to meet soil or rock conditions.
SOIL CONDITIONING and BACKFILL GROUTING
• Inject additive and form to cutting volume 30-40% per ring. To control an
appropriate plastic flow and the impermeability for the excavated soil.
• Inject backfill grout volume to the void 110-130% per ring. To fill the void
immediately and inhibit the looseness of the ground.
SOIL CONDITIONING UNIT
• Additive injection such as foam and polymer are used to mix with the soil to
maintain it plasticity.
• In ground with less fine content and high permeability such as sand, it is
difficult to control plastic flow. Polymer or bentonite need for control ground
water and reduce permeability.
BACKFILL GROUT
• Two ways to inject the backfill grout either grout pipe install at the tail of the
TBM body or grout through the injection hole of the segment (grout plug).
•
•
GREASE STATION
• Grease lubrication (Gear oil and No.1 grease), ensure the cutter bearing,
seal, gears are properly lubricated.
TAIL SEAL GREASE
• Tail seal grease (special
compound), designed to
seal the tail end against
ground water and grout.
• To have anti washout
properties and wear
protection for the brushes.
Pumpable.
Thank you
Any Question?
MRT PURPLE LINE (SOUTH SECTION) PROJECT : CONTRACT C3
f6.39m EPB TBM CUTTER BIT WEAR ASSUMPTION
TBM#1
PP22
Shaft
Cutting Condition
PP23
Dwall
CLAY
Dwall
Dwall
CLAY
SAND
Dwall
1.2
1.2
IVS#4
IVS#5
Clay
Dwall
CLAY
SAND
CLAY
Dwall
Dwall
CLAY
SAND
CLAY
SAND
Dwall
300
1.2
PP24
Dwall CLAY
Dwall
450
1.2
350
50
1.2
1.2
280
350
100
1.2
200
70
230
80
1.2
320
80
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
Excavation Speed (mm/min)
2
35
2
2
35
30
2
30
2
35
30
35
2
2
30
35
30
35
2
2
35
30
2
12.1
259.3
12.1
12.1
201.7
33.6
12.1
201.7
12.1
161.4
235.3
57.6
12.1
12.1
134.5
40.3
154.6
46.1
12.1
12.1
184.4
53.8
12.1
0.04
0.008
0.04
0.04
0.008
0.0368
0.04
0.008
0.04
0.008
0.0368 0.008
0.04
0.04
0.008
0.037
0.008
0.0368
0.04
0.04
0.008
0.0368
0.04
0.5
2.1
0.5
0.5
1.6
1.2
0.5
1.6
0.5
1.3
0.5
1.1
1.5
1.2
1.7
0.5
0.5
1.5
2.0
0.5
per SECTION
3.0
Total
70
Precede Bit wear limit (mm) (Difference from main bit.)
Cutter Bit Wear Factor (mm/km)
0.015 0.003 0.015
Est. Precede bit wear volume (mm)
per section
Total
Precede Bit wear limit (mm) (Tip Height/2)
0.2
0.8
0.2
3.8
70
0.015 0.003
0.2
0.0138 0.015
0.6
0.5
0.2
THROUGH
8.7
0.5
0.5
13.0
70
0.003 0.015 0.003
0.6
0.2
0.0138 0.003 0.015
0.5
3.2
0.2
0.2
THROUGH
6.5
70
0.015
0.003
0.014
0.2
0.4
0.6
IVS#3
0.003
0.015
0.5
0.1
0.2
70
0.015 0.003
0.2
0.0138 0.015
0.6
0.7
4.9
1.9
1.7
20
20
20
20
20
PP24
IVS#5
1
4.4
1.4
IVS#4
1.2
LAUNCH
1.1
PP23
PP22
0.003
TBM Cutter bit inspection
Precede bit wear factor (mm/km)
Est. Precede bit wear volume (mm)
THROUGH
TBM Cutter bit inspection
Total cutter rotation distance Length (km)
THROUGH
TBM Cutter bit inspection
ARRIVAL
Direction
1.2
SAND
Cutter Rotation speed (rpm)
TBM Cutter bit inspection
Section length (m)
IVS#3
0.2
III. COUNTERMEASURES
WATER PRESSURE CONTROL
WATER PRESSURE CONTROL
PROBE DRILL
III. COUNTERMEASURES
WATER PRESSURE CONTROL
CONSOLIDATION GROUTING
(Image)
III. COUNTERMEASURES
WATER PRESSURE CONTROL
DOUBLE SCREW CONVEYOR SYSTEM
III. COUNTERMEASURES
WATER PRESSURE CONTROL
WATER DRAIN SYSTEM
III. COUNTERMEASURES
WATER PRESSURE CONTROL
WATER CONTROL PROCEDURE
1.
2.
3.
4.
CLOSE No.1 / No.2 SCREW GATE
REMOVE THE BOLT
RETRACT THE No.1 SCREW CONVEYOR
CLOSE THE CHAMBER GATE
III. COUNTERMEASURES
WATER PRESSURE CONTROL
WATER CONTROL PROCEDURE
5. SETTING THE PROBE DRILL
6. DRILLING AND GROUTING
III. COUNTERMEASURES
WATER PRESSURE CONTROL
GROUTING SYSTEM
2 LIQUID TYPE GROUTING
INJECTION LIQUID
CONSOLIDATED
GROUTING
III. COUNTERMEASURES
WATER PRESSURE CONTROL
OTHER COUNTERMEASURE (e.g. GROUND FREEZING)
III. COUNTERMEASURES
GROUND CONDITION CHANGES
GROUND CONDITION CHANGES
CUTTER HEAD
FOR ROCK GROUND
(DISC CUTTER)
FOR SOFT GROUND
(PRECEDE BIT)
III. COUNTERMEASURES
GROUND CONDITION CHANGES
CHAMBER LEVEL CONTROL
ROCK
(OPEN MODE)
SOIL
(CLOSED MODE)
III. COUNTERMEASURES
GROUND CONDITION CHANGES
HYPERBARIC EQUIPMENT(MAN LOCK and MATERIAL LOCK)
III. COUNTERMEASURES
SALTY GEOLOGICAL CONDITION
SALTY GEOLOGICAL CONDITION
Countermeasures to manage the risk of erosion
Skin Plate Thickness
Cylinders (Prevent corrosion)
Tail Brush
Electric Parts
Consider the Corrosion Thickness (Approx. 1-2mm)
(for Large size) Chromium carbide rod coating
(for Small size) Stainless steel rods
Stainless steel brush and spring plate
Consider positioning and covering
Stainless steel type Tail Seal
(Wire brush, Spring plate)
Chromium carbide
rod coating material
III. COUNTERMEASURES
SQUEEZING MITIGATION
SQUEEZING MITIGATION
SHIELD BODY (CONICAL SHAPE)
10mm GAP
10mm GAP
Copy
Cutter
Bentonite
Injection
Port
FRONT SHIELD
DIAMETER
‐20mm
TAIL SHIELD
MIDDLE SHIELD
DIAMETER
‐20mm