Geotechnical Engineering Aspects of Trans-Tokyo Bay Highway Project

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Geotechnical Engineering Aspects of Trans-Tokyo
Bay Highway Project TATSUOKA, F. Professor,
University of Tokyo UCHIDA, K. Nippon
Engineering Consultants, formerly, Managing
Director, Trans-Tokyo Bay Highway
Corporation and OUCHI, T. Toa Corporation,
formerly, Assistant Manager, Design and
Engineering Dept., Trans-Tokyo Bay Highway
Corporation
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Trans-Tokyo Bay Highway
15.1 km-long toll highway
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Brief history
May 1971 The technical investigation
started. May 1983 The Japanese
Government approved the construction.
October 1986 The Trans-Tokyo Bay Highway
Corporation was established. May 1989
The construction started. December 1997 The
construction completed and the highway was
opened to public on 18th December.
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Brief history
May 1971 (25) The technical investigation
started. May 1983 (37) The Japanese
Government approved the construction.
October 1986 (40) The Trans-Tokyo Bay
Highway Corporation was established. May
1989 (43) The construction
started. December 1997 (51) The construction
completed and the highway was opened to
public on 18th December.
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Structure of TTB Highway
Ukishima access Two 9.5
km-long shield tunnels Kawasaki man-made
island Kisarazu man-made island Bridge
PLAN
PROFILE
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Structure of TTB Highway
Ukishima access Two 9.5
km-long shield tunnels Kawasaki man-made
island Kisarazu man-made island Bridge
PLAN
PROFILE
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Structure of TTB Highway
Ukishima access Two 9.5
km-long shield tunnels Kawasaki man-made
island Kisarazu man-made island Bridge
PLAN
PROFILE
8
Structure of TTB Highway
Ukishima access Two 9.5
km-long shield tunnels Kawasaki man-made
island Kisarazu man-made island Bridge
PLAN
PROFILE
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Structure of TTB Highway
Ukishima access Two 9.5
km-long shield tunnels Kawasaki man-made
island Kisarazu man-made island Bridge
PLAN
PROFILE
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Four difficult design conditions that controlled
the structural form
a relatively deep sea heavy shipping routes
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Four difficult design conditions that controlled
the structural form
a relatively deep sea heavy crossing shipping
routes poor ground conditions and a high
seismic activity.
Late Holocene very soft clay
Early Holocene sand and clay
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Trans-Tokyo Bay Highway
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Ukishima access
Kisarazu man-made island
Kawasaki man-made island
Bridge
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Ukishima access
The starting point of the shield tunnels,
towards the center of the Tokyo Bay
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• Steel caisson
• to start the shield tunnel construction
• the ventilation tower after competition.

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• Steel caisson
• to start the shield tunnel construction
• the ventilation tower after competition.

Approach fill, retaining shield tunnels.
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Ukishima access
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Kawasaki man-made island
Cross-section
Artists view of the completed structure
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(No Transcript)
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A ring space for a diaphragm wall
190 m
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Kisarazu man-made island
Shield tunnels
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Two 9.5 km-long shield tunnels
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2
2
2
Two tubes constructed The third one in the
future.
Eight shield tunnel machines worked
simultaneously to reduce the total construction
period.
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Two 9.5 km-long shield tunnels
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Blind type using pressurized mud slurry
The worlds largest diameter at the time of
construction
14.14 m
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Shield tunnel machine re-assembled to start from
Kawasaki m-m island
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Two 9.5 km-long shield tunnels
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RC segments
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Secondary inner RC lining (inside the RC segments)
RC segments
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Significant design and construction issues
related to geotechnical engineering - 1
Large-scale improvement of existing soft clay
deposits by in-situ cement mixing, -
controlling the strength of cement-mixed soft
clay and - in total 3.77 million m3.
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Ukishima access

• Very soft clay improved
• by in-situ cement-mixing,
• achieving a controlled
• strength i.e.,
• strong enough for the stability of the structure
  and
• weak enough for smooth tunnelling.

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In-situ cement mixing of soft clay deposits
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Controlled shear strength of cement-mixed soft
clay
?t (gf/cm3)
qmax (kgf/cm2) (t 28 days)
wn ()
Compressive strength after cement mixing qu
by unconfined compression tests x qmax by CU
TC tests Original ground qu (kg/cm2)
0.044z 0.88 (z depth z 0 m at TP
0.0).
(m)
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Significant design and construction issues
related to geotechnical engineering - 2

• Construction of large embankments by using
• cement-mixed sand slurry with a controlled
  strength
• at the ramp sections.

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Ukishima access
Embankment of cement-mixed sand slurry with a)
a controlled strength and b) a controlled
high density to resist the buoyant force
of the tunnels.
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Underwater placement of cement-mixed sand slurry
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(No Transcript)
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Strength of cement-mixed sand slurry (Ukishima
site)
Samples of the slurry before placed under
water, obtained during placement work (the
strength is similar to the prescribed value)
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Samples from underwater obtained during
placement work (very likely largely
under-estimated) based on this result, the
amount of cement was increased perhaps
unnecessarily.
Strength of cement-mixed sand slurry
Strength of cement-mixed sand slurry (Ukishima
site)
Samples of the slurry before placed under
water, obtained during placement work (the
strength is similar to the prescribed value)
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Samples from underwater obtained during
placement work (very likely largely
under-estimated)
Strength of cement-mixed sand slurry
Strength of cement-mixed sand slurry (Ukishima
site)
Samples of the slurry before placed under
water, obtained during placement work (the
strength is similar to the prescribed value)
Samples obtained by RCT sampling from bore holes
made in the fill, obtained after the competition
of the fill (reliable)
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Significant design and construction issues
related to geotechnical engineering - 2

• Construction of large embankments by using
• cement-mixed sand slurry with a controlled
  strength
• at the ramp sections and
• dry cement-mixed sand at the flat place of
• Kisarazu man-made island.

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Underwater placement of dry mixture of
cement-mixed sand (Kisarazu man-made island)
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Underwater placement of dry mixture of
cement-mixed sand (Kisarazu man-made island)
Special double-chute
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Underwater placement of dry mixture of
cement-mixed sand (Kisarazu man-made island)
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Ground improvement techniques by cement-mixing
used in the TTB Highway project Cement-treatmen
t method Mixing proportion Construction
site Volume 1,000 m3 Ordinary DMM
Cement 140 kg/m3
W/C ratio 100
Kawasaki m-m island 132 Low
strength-type DMM Cement 70 kg/m3
Ukishima Access 1,248
W/C
ratio 100 Kisarazu m-m isl.
289

Kawasaki m-m isl. 168 Slurry
type cement-mixed Sand 1,177 kg/m3
Ukishima Access 1,028 sand (
80 kg/m3 in the Cement 100 kg/m3
Kisarazu m-m isl. 351 original
design) Clay 110 kg/m3
Kawasaki m-m isl. 118
Sea
water 505 kg/m3 Dry mixture type
Sand 1,330 kg/m3 Kisarazu m-m isl.
435 cement-mixed sand
Cement 100 kg/m3
Anti-segregation
adhesive 110 g/m3
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Summary of elastic Youngs moduli of the
cement-treated soils in the TTB Project
Emax defined for strains less than 0.001 from
triaxial compression tests using LDTs on
undisturbed samples (kgf/cm2)
Ef from field shear wave velocity Vs (kgf/cm2)
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Significant design and construction issues
related to geotechnical engineering - 3
Construction of shield tunnels a) successively
in very stiff cement-mixed soil and very soft
clay at a very shallow depth
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Ukishima access
Very soft clay with a very thin overlaying soft
clay
Very stiff cement-mixed soil
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Ukishima access
Two tunnels from Ukishima
A sudden large change in the cutting torque
of shield machine (tonf-m)
Ring number (one ring 1.5 m)
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Cutter torque (tf-m)
Top of tunnel
Centre of tunnel
Bottom of tunnel
CU TC strength qmax (Fill of cement-mixed
sand slurry)
qu (LS DMM)
qmax(LS DMM)
Compressive strength, qu or qmax (kgf/cm2)
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Ukishima access
Very soft clay with a very thin overlaying soft
clay
A danger of floating up of the tunnels by large
buoyant force acting to the tunnels, compared to
a small surcharge prevented by placing weight
in the tunnels and careful tunnelling work.
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Significant design and construction issues
related to geotechnical engineering - 3
Construction of shield tunnels with the worlds
largest diameter a) successively in stiff
cement-mixed soil and very soft clay at a very
shallow depth and b) underground connection of
shield machines with the help of ground
freezing to shorten the drive of each tunnel.
Locations of tunnel connection
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Underground connection of shield machines with
the help of ground freezing
Longitudinal section
Cutting face
Cutting face
First arrived shield tunnel
Second arrived shield tunnel
Freezing pipe
Frozen zone
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Significant design and construction issues
related to geotechnical engineering - 4

• A huge offshore
• diaphragm wall
• 98 m in int. dia.
• 119 m in height
• for Kawasaki
• man-made island.

An artists view from the beneath
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Kawasaki man-made island
Immediately after the end of ground excavation
Immediately before the ground excavation
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Ground improvement by sand compaction pile
technology
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Ground improvement by sand compaction pile
technology
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Kawasaki man-made island
Immediately after the end of ground excavation
Immediately before the ground excavation
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Construction of external and internal steel
structures after necessary ground improvement
work
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(No Transcript)
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Filling up the ring space with cement-mixed sand
slurry
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Construction of a diaphragm wall in the
cylindrical ring of cement-mixed sand fill and
cement-mixed in-situ soft clay
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Excavation machine
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(No Transcript)
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Excavation of the inside ground
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Excavation of the inside ground
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Construction of the internal structure inside the
diaphragm wall
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Construction of the internal structure
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Deep well system to avoid the ground failure by
seepage
Observation wells
Drainage wells
Diaphragm wall
A-sandy layer
Thin clay layer
B-sandy layer
Thick clay layer
C-sandy layer
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Observation wells
Drainage wells
Diaphragm wall
A-sandy layer
Thin clay layer
A serious seepage accident Start of unusual
ground water spouting 14th Nov. 1993
B-sandy layer
C-sandy layer
Thick clay layer
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Time histories of ground water spouting and
water depth inside the diaphragm wall
Depth of water inside the diaphragm wall (m)
Amount of spouting ground water (m3 per day)
First stage
Second stage
Depth of water in the diaphragm wall
Increase in the rate of ground water spouting
Amount of spouting ground water
Start of pouring sea water into the inside of
the diaphragm wall
Start of unusual spouting of ground water
Date for a period from 14 November to 4th
December 1993
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Sea water poured to reduce the hydraulic gradient
in the ground inside and immediately below the
the diaphragm wall
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Restart of construction after a delay of six
months
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(No Transcript)
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CONCLUDING REMARKS-1 The Trans-Tokyo Bay Highway
was constructed a) in a relatively deep sea b)
crossing heavy shipping routes c) under poor
ground conditions and d) with a high seismic
activity. Several geotechnical engineering
design and construction problems had to be solved
for the success of the project.
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CONCLUDING REMARKS-2 The ground improvement by
four types of cement-mixing technologies solved
a number of potential technical problems 1)
in-situ cement mixing of very soft clay a)
conventional type deep mixing method (DMM) and
b) low strength-type DMM and 2) embankment
using a) slurry type cement-mixed sand and
b) dry mixture type cement-mixed sand.
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CONCLUDING REMARKS-3
Successful construction of shield tunnels with
the worlds largest diameter, overcoming several
difficult technical problems, including a)
successive tunnelling in very stiff cement-mixed
soil and very soft clay b) a very shallow depth
in a very soft clay with a danger of
floatation of the tunnels and c) underground
connection of shield machines with the help
of ground freezing to reduce the shield
tunnel drive.
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CONCLUDING REMARKS-4

• The construction of an offshore diaphragm wall
  with an
• int. dia. of 98 m and a height of 119 m was
  delayed
• a half year by a serious seepage accident in the
  ground
• inside the diaphragm wall.
• The accident would have become a fatal one for
  the success of the project if relevant measures
  were not taken promptly.
• The accident might have not taken place if the
  hydraulic gradient in the ground inside and
  immediately below the diaphragm wall had been
  made substantially lower, for example, by making
  the bottom of the diaphragm wall substantially
  deeper than the actual one.

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Thank you very much for your attentions !