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					9th February 2000

Ground Improvement by Cement-Mixing

 ・ Deformation and strength characteristics
  of cement-mixed soil, compared with those
  of sedimentary soft rock

 ・Development of a very large high stiffness stress zone
  by cementation

 ・Permanent critical structures made of cement-mixed soil
・ Deformation and strength characteristics
 of cement-mixed soil, compared with those
 of sedimentary soft rock
                   Brief history of TTB
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.
         Structure of TTB Highway
・Ukishima access;          ・Two 9.5 km-long shield tunnels;
・Kawasaki man-made island; ・Kisarazu man-made island;
・Bridge

                           PLAN




                         PROFILE
        Structure of TTB Highway
・Ukishima access;          ・Two 9.5 km-long shield tunnels;
・Kawasaki man-made island; ・Kisarazu man-made island;
・Bridge

                          PLAN




                         PROFILE
        Structure of TTB Highway
・Ukishima access;          ・Two 9.5 km-long shield tunnels;
・Kawasaki man-made island; ・Kisarazu man-made island;
・Bridge

                           PLAN




                         PROFILE
        Structure of TTB Highway
・Ukishima access;          ・Two 9.5 km-long shield tunnels;
・Kawasaki man-made island; ・Kisarazu man-made island;
・Bridge

                           PLAN




                         PROFILE
        Structure of TTB Highway
・Ukishima access;          ・Two 9.5 km-long shield tunnels;
・Kawasaki man-made island; ・Kisarazu man-made island;
・Bridge

                           PLAN




                         PROFILE
   Four difficult design conditions
   that controlled the structural form
・a relatively deep sea;
・heavy shipping routes;
    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
                              Ukishima access


Kisarazu man-made island



                      Kawasaki man-made island


          Bridge
Ground improvement techniques by cement-mixing
used in the TTB Highway project


Cement-treatment 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
     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
Ukishima access




                  Very soft clay improved
                  by in-situ cement-mixing,
                  achieving a controlled
                  strength; i.e.,
                  a) strong enough for the
                      stability of the
                      structure; and
                  b) weak enough for
                      smooth tunnelling.
In-situ cement mixing
of soft clay deposits
      Controlled shear strength of cement-mixed soft clay

        wn (%)    γt (gf/cm3)   qmax (kgf/cm2) (t= 28 days)


                                           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)



        The unconfined compression strength: not reliable !
       Significant design and construction issues
       related to geotechnical engineering - 2:

Construction of large embankments by using
cement-mixed sand slurry with a controlled strength and
density
 at the ramp sections.
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.
Underwater placement of
cement-mixed sand slurry
1988
A large scale underwater placement test
In a shipping building dock in Ichihara City, Chiba
Reduction of the strength
by absorbing water
during under-water
placement
Reduction of the strength by absorbing water
during under-water placement
Undisturbed sampling of:
1) large (30 cm in dia.); and
2) small (5 cm in dia.)


It was considered that:
because of non-uniformity of
the under-water placed material,
the strength of small samples
may over-estimate the in-situ
strength.

(It was found later that it was
not the case).
                                                          Membrane


                                                              Pseudo-hinge




                                                                                                                                        Instrument
Phosphor bronze                                                    LDT                                                                  leadwire
                                                                                                            Gage leadwire Terminal
                                                                                          Active e.r.s.g.
strain-gaged strip                                                                                               B'
                                                                                                   No. 1
                                                                                                                            A
                                                                                                                  D'        C
                                                                                                   No. 2


                                        Heart of LDT                                  Teflon tube protection
                                                                                                                                                     PB strip
                                        (includes electric resistance strain gages,                                    Front face (tension side)
                                                                                           (Front)
                                         terminals, wiring, sealant)

                                        Scotch tape used to fix wire                                No. 3
                                                                                                                 A'
                                                                                                                             D
                                        on the specimen surface                                     No. 4
                                                                                                                      C'    B



                                                                                                                      Back face (compression side)


                                                                                        (Back)
                                           Instrument Leadwire
                     Membrane Surface



             LDT; Local deformation transducer (Goto et al., 1991).
                                                                                                                                                                Fig
Triaxial compression test
on an undisturbed sample
(5 cm in dia. and 10 cm high)
from the large scale placement
test of cement-mixed sand
(slurry type)


A significant amount of error
The first case where:
1. LDT was used for a practical
  case; and
2. the elastic modulus from
 triaxial tests exhibits nearly
 the same value with that
 from the field shear wave
 velocity.
The Young’s modulus value
that had been obtained by
a geotechnical consultant:
E50 = 3,000 kgf/cm2
(by conventional unconfined
compression tests)
This value considerably
underestimates the true
elastic modulus:
E= 30,000 kgf/cm2
and also the value at the
operating strain !

The engineers can become
confident with using this
material for this project !
Laboratory and field test data; consistent with each other
             only when strain-non-linearity is considered.
Filling up the ring space
with cement-mixed sand slurry,
Kawasaki man-made island
Triaxial testing system
for small specimens
at the University of Tokyo.
A typical test result on an undisturbed sample
     of cement-mixed sand (slurry type)
Comparison of
the elastic Young’s moduli
from TC tests (Emax)
and
those from field Vs (Ef)
at the embankment of
cement-mixed sand
(slurry type),
Kawasaki man-made
island
Rotary core tube sampling;
a) to obtain undisturbed
    samples; and
b) to measure elastic wave
  velocities.
 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 from
underwater               Strength of
obtained during
placement work           cement-mixed
(very likely largely     sand slurry
under-estimated);
based on this result,
                         (Ukishima site)
the amount of
cement was
increased perhaps
                        Samples of the slurry
unnecessarily.
                        before placed under
                        water, obtained during
                        placement work
                        (the strength is similar
                        to the prescribed value)
Samples from
underwater                  Strength of
obtained during
placement work              cement-mixed
(very likely largely        sand slurry
under-estimated)
                            (Ukishima site)


                           Samples of the slurry
                           before placed under
                           water, obtained during
Samples obtained by        placement work
RCT sampling from          (the strength is similar
bore holes made in the     to the prescribed value)
fill, obtained after the
competition of the
fill (reliable)
Comparison of elastic the Young’s moduli from TC tests (Emax) and
those from field Vs (Ef) at the embankment of cement-mixed sand
(slurry type), Ukishima Access
       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.
Underwater placement of
dry mixture of cement-mixed sand
(Kisarazu man-made island)
Underwater placement of
dry mixture of cement-mixed sand
(Kisarazu man-made island)
                                                              Proximeter for v
                                                        v
                                 Lubricated                        9.5 cm




                                                                       Vertical LDT
                                     h                            19 cm




                                                                       Lateral LDT


                                                                    Proximeter for h
                               H=57 cm




                                                                           9.5 cm

                                                                  3.5 cm
                                    see
                                    Fig. 2b



                                                             W=23 cm
                                              W=23 cm




Large rectangular prismatic undisturbed specimen of cement-
mixed sand (dry type) from a large-scale placement test
with local axial and lateral strain measurements.
Comparison of
elastic the Young’s moduli from
TC tests (Emax)
and
those from field
shear wave velocities (Ef)
at the embankment of
cement-mixed sand (dry type),
Kisarazu man-made island
              Summary of elastic Young’s 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)
Ground improvement techniques by cement-mixing
used in the TTB Highway project


Cement-treatment 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
      Hawaii, on the summit of Mauna Kea
To increase the natural frequency of the telescope system,
much larger the predominant frequency of noise
CD triaxial compression test
on a compacted specimen
of volcanic cinder mixed
with cement
Totally different conclusions
based on results obtained
by using different                Different by 40 times!
Measurement methods:

A reasonable design only
when based on accurate results.
Sedimentary soft rock
as the ground supporting important heavy structures
     Settlement of the foundations for Rainbow Bridge




1) Foundations on a sedimentary soft rock.
2) The fist caisson foundations without piles.
                                    TS=fixed-piston thin-wall sampling        Cement-treated soil
                                    BS=block sampling                         Slurry Dry DMM
                                    DC=direct coring                    RCT
                                    RCT=rotary coring                  BS+DC
                                                          Sedimentary soft rock
                                         Kazusa Kobe Sagara Miura Tokoname Uraga-A Uraga-B
                                   RCT
G0 values from                    BS+DC
                                                              5000
CU TC tests                                                          Local axial strain measurements




                   (=0.5 for clays and 0.42 for softrocks)
versus                                                        1000


                            G0=E0/{2(1+)} (MPa)
                                                                      Range for Soft rocks and
                                                                      Cement-treated soils
                                                                      (BS+DC) and clays
Gf from
field shear wave
                                                              100
velocities                                                                                        Pleistocene clay site
                                                                                          Tokyo Osaka OAP Suginami
                                                                                           bay bay
                                                                           )
                                                                       :1
                                                                      (1


                                                                                    )
                                                                                :2

                                                                                        TS
                                                                               (1




                                                                                        BS
                                                               10
                                                                 10                     100                  1000         5000
                                                                                                       2
                                                                                              Gf=(Vs)vh   (MPa)
 Comparison of the strength and deformation characteristics of
 cement-mixed and natural sedimentary soft rock




                Sedimentary
                soft rock


                                                  Cement-mixed
                                                  soil
Cement-mixed soil having
a controlled strength
                   Summary:
1) The strength and deformation characteristics* of cement-mixed
   soil could be made similar to those of natural sedimentary soft
  rock. (* should be measured accurately)
2) When soil can be mixed with cement rather uniformly and
   the quality would not deteriorate with time (both being not
   difficult), important critical civil engineering structures, such as
   bridge piers, could be constructed by using cement-mixed soil
   or the ground of cement-mixed soil could support
   such important structures.
・Development of a very large high stiffness stress
 zone by cementation
High-water content marine clay mixed with small
amount of cement
                               600
                                            クリープ・再載荷後の
                                            ピーク応力点
                               500
                                          σ3一定載荷
                                                                               K=0.5 載荷
    Deviator stress, q (kPa)




                               400       クリープ応力点


                                                                              等方圧密供試体の
                               300                              再形成
                                                                              ピーク応力点
                                                                降伏曲面②
                                                                            再形成降伏曲面③
                               200


                                                         q一定載荷
                               100
                                                         初期
                                                                           σ3一定載荷時の降伏点
                                                       降伏降伏曲面①
                                0
                                     0       200         400         600          800      1000
  等方圧密による降伏点                                  Effective mean principal stress•C p' (kPa)
                           Development of a high stiffness stress zone
                           600
                                      クリープ後                                   クリープ後
                                      σ3一定載荷                                  K=0.5 載荷
                           500
Deviator stress, q (kPa)




                           400
                                  降伏点②

                                                                  クリープなし
                           300
                                                                  (K=0.5 載荷)
                                                        クリープ後
                                                        q一定載荷 
                           200
                                 降伏点①
                                              クリープ(7日)
                           100
                                         K=0.5 載荷

                            0
                                  0       1         2        3            4      5       6
                                              Axial strain, a(LDT) (%)
                             600
                                          クリープ・再載荷後の
                                          ピーク応力点
                             500
                                        σ3一定載荷
                                                                             K=0.5 載荷
  Deviator stress, q (kPa)




                             400       クリープ応力点


                                                                            等方圧密供試体の
                             300                              再形成
                                                                            ピーク応力点
                                                              降伏曲面②
                                                                          再形成降伏曲面③
                             200


                                                       q一定載荷
                             100
                                                       初期
                                                                         σ3一定載荷時の降伏点
                                                     降伏降伏曲面①
                              0
                                   0       200         400         600          800      1000
等方圧密による降伏点                                  Effective mean principal stress•C p' (kPa)
                                     Sand mixed with a small amount of cement
                                                             ST16                       ST14
                                14                                        ST8
                                                     ST4

                                12

                                              ST11
Deviator stress , q (kgf/cm )




                                                                                       ST18
2




                                10

                                        ST6                                                                  ST2
                                 8

                                                                                CD TC test
                                 6                                                                3
                                                                                d= 1.34 gf//cm
                                                                                cement/sand = 4%
                                                                                                   2
                                 4                                              'c = 2.0 kgf/cm
                                                                                Cured at wi = 12.5%
                                                                                Sheared saturated
                                 2


                                 0
                                  0.0         0.1      0.2          0.3          0.4           0.5     0.6         0.7
                                                       Axial strain (locally measured), a (%)
Deviator Stress , q (kgf/cm )   10
2


                                       Sample ST4

                                 9


                                 8
                                                        Loading was stopped
                                       Start of creep
                                                        for 10 days
                                 7


                                 6
                                                4 unload - reload cycles

                                0.11     0.12   0.13    0.14   0.15   0.16   0.17   0.18
                                         Axial Strain (locally measured) , a (%)
・Permanent critical structures made of
cement-mixed soil
        (5) Bridge girder             (2) RC abutment



 (4) Displacement                            (3) Backfill
    of the abutment
   due to the earth pressure                (4) Earth pressure

                                                    Ground
As the abutment and piles
have to resist against                  (4) Settlement and lateral
these earth pressure and                   flow of ground; and
ground movements (4),                     associated negative friction
they have to be very
                               (1) piles and bending of the piles
massive and strong.

  Inherent problems with conventional bridge abutments
  (the numbers imply the event sequence)
        (4) Bridge girder           (1) Cement-mixed soil



                                           (1) Backfill
      (3) A FHR facing

         Connected


As the FHR facing is constructed                 Ground
after the deformation of ground
and backfill has taken place,         (2) Settlement and lateral
a massive RC abutment and deep           flow of ground
piles become unnecessary.


 Advantages of cement-mixed soil bridge abutments
 (the numbers imply the event sequence)

				
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