BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
Chöông 3
Gia cöôøng ñaát yeáu vôùi phöông phaùp taêng cöôøng
vaät lieäu chòu keùo
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
1. V¶i hoÆc líi ®Þa kü thuËt
HiÖn nay ë níc ta ®ang ¸p dông réng r·i ph¬ng
ph¸p v¶i /líi ®Þa kü thuËt ®Ó c¶i t¹o vµ æn ®Þnh
®Êt yÕu. §©y lµ nh÷ng tiÕn bé kü thuËt trong x©y
dùng ®êng vµ nhµ Ýt tÇng. V× vËy cÇn n¾m v÷ng
nh÷ng hiÓu biÕt c¬ b¶n sau ®©y:
Ph¹m vi ¸p dông cña ph¬ng ph¸p (b¶ng 7.5 vµ b¶ng
7.6);
Lùa chän ®óng ph¬ng ph¸p;
ThiÕt kÕ bè trÝ theo nh÷ng tiªu chuÈn t¬ng øng;
N¾m ®îc nh÷ng yªu cÇu c¬ b¶n cña tõng ph¬ng
ph¸p khi lùa chän c¸ch tho¸t níc;
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
KiÓm tra kÕt qu¶ xö lý : hÖ thèng quan tr¾c lón theo thêi gian vµ
sù tiªu t¸n ¸p lùc níc lç rçng, chuyÓn vÞ ngang
§èi víi v¶i ®Þa kü thuËt theo c¸c tiªu chuÈn :
LÊy mÉu vµ xö lý thèng kª ( theo TCN-1);
X¸c ®Þnh ®é dµy tiªu chuÈn ( theo TCN-2);
X¸c ®Þnh khèi lîng ®¬n vÞ diÖn tÝch (theo TCN-3);
X¸c ®Þnh ®é bÒn chÞu lùc kÐo vµ d·n dµi (theo TCN-4);
X¸c ®Þnh ®é bÒn chäc thñng (theo TCN-5);
X¸c ®Þnh kÝch thíc lç v¶i (theo TCN-6);
X¸c ®Þnh ®é thÊm xuyªn (theo TCN-7);
X¸c ®Þnh ®é dÉn níc bÒ mÆt (theo TCN-8);
X¸c ®Þnh ®é bÒn chÞu tia cùc tÝm (theo TCN-9).
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
B¶ng 7.5. Kh¶ n¨ng ¸p dông biÖn ph¸p kü thuËt c¶i t¹o nÒn cho c¸c lo¹i ®Êt kh¸c nha
C¬ chÕ caûi t¹o
Cèt
Hçn hîp trén
hay phôt vöõa
ÑÇm
chÆt
Tho¸t níc
Thêi gian c¶i t¹o
Phô thuéc sù
tån t¹i cña thÓ
vïi
T¬ng ®èi
ng¾n
L©u dµi
L©u dµi
ÑÊt höõu c¬
ÑÊt sÐt cã nguån gèc
nói löa
ÑÊt sÐt ®é dÎo cao
ÑÊt sÐt ®é dÎo thÊp
ÑÊt bïn
ÑÊt c¸t
ÑÊt sái
Tr¹ng th¸i caûi t¹o
cña ®Êt
T¬ng t¸c giöõa
®Êt vµ thÓ vïi
(Kh«ng thay
®æi tr¹ng th¸i
®Êt)
Xi maêng ho¸
Dung träng cao do
hÖ sè rçng giaûm
(Thay ®æi tr¹ng th¸i ®Êt)
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
B
Qult
d>2/3B
B
Qult
T
T
d< 2/3B
(B)
(A)
B
Qult
d < 2/3B
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
B
Qult
Df
A
X0
txz(max)
A’
Zone I A’’
z
x
A’’’
Zone II
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
F1 – F2 – S1 = 0
B
q0
F3 – F4 – S2 – T(N=1) = 0
Df
•* S = w = [{Bq(1-2)}/E]
x
(q0)
F1
• F2 = F4
S1
H
•T(N=1) = F3 – F1 – S2 + S1
F2
z
X0
X0
F1    (q 0 ) dx
B
0
F3    (q R ) dx
0
qR
Df
x
F3
S2
H
F4
z
X0
X0
S1  t xz (q 0 )H
S 2  t xz (q R )H
2
2
2
(qR)  (q)  q tan 1 z  tan 1 z  2bz ( x  z  b ) 

 
xb
x  b ( x 2  z 2  b 2 ) 2  4b 2 z 2 
T(N=1)
4bqX 0 z 2
t xz (q) 
 [ X 02  z 2  b 2 ) 2  4b 2 z 2 ]
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
B
qR
Df
x
(qR)
F3
S2
H
F4
z
T(N=1)
X0
L0
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
F1 = A1q0B
F3 = A1 qR B
S1 = A2 q0 H
S2 = A2 qR H;
A1 &A2 = f(z/B)
* b = B/2
T(N=1) = A1 qR B – A1 q0 B –A2 qR H +A2 q0 H
= A1 B (qR – q0) – A2 H (qR – q0)
q

T( N 1)  q0  R  1( A1B  A2 H )
 q0 
T( N )
1  qR 

 q0   1( A1B  A2 H )
N
N  q0 
T( N 1)
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
0.4
0.35
0.3
A1,A2,A3
0.25
A1
A2
0.2
A3
0.15
0.1
0.05
0
0
0.5
1
1.5
2
z/B
2.5
3
3.5
4
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
FS( B )
 t n f y tf y


LDR
T( N )
T( N )
L0


FB  2tg a ( LDR )( )( L0  X 0 )( z  D f )]    (qR )dx 


X0
 qR 
FB  2 tan a ( LDR )[ A3 Bq 0     ( L0  X 0 )( z  D f )]
 q0 
FS ( P )
FB

T( N )
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
4.5
4
3.5
L0/B
3
2.5
2
1.5
1
0
0.5
1
1.5
2
z/B
2.5
3
3.5
4
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
 = 17,3 kN/m3;  = 350 ; Es = 3x104 kN/m2;  = 0.35
Df = 1m, FS=3, s = 2,5cm, t= 50 ans
fy= 2.5x10 kN/m2 ; a=280; FS(B)=3; FS(P) = 2,5.
 B=1m

N = 5 ; H = 0,5m, LDR=65%
qu = DfNq+(1/2)BN,
Vesic(1973), =350  Nq = 33,3; N = 48,03.
qu = 17,3x1x33,3+(1/2)x17,3x1x48,03=922kN/m2
Qall(1)_ = 331 kPa
2
Bq
Es  s
2
(
30
.
000
kN
/
m
)(0.025m)
S
(1   s ) r  qall( 2) 

 427kPa
2
2
Es
B(1   s ) r
(1  m)(1  0.35 )( 2)
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
1.8MN / m 1.8 103
qR 

 1.8 103 kN / m 2
B
1
 q0  qR 
TN     1( A1  B  A2  H )
 N  q0 
N=
q0
N
 qR 
 1
 q0 
z(m)
z
B
A1B
A2H
A1B- A2H
TN
(kN)
1
293,7
0,5
0,5
0,35
0,125
0,225
66,08
2
293,7
1
1
0,34
0,09
0,25
73,43
3
293,7
1,5
1,5
0,34
0,065
0,275
80,77
4
293,7
2
2
0,33
0,05
0,28
82,24
5
293,7
2,5
2,5
0,32
0,04
0,28
82,24
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
Ñaïi löôïng tính
Lôùp gia cöôøng N soá
1
2
3
4
5
2tana(LDR)
0,691
0,691
0,691
0,691
0,691
A3
0,125
0,14
0,15
0,15
0,15
A3Bq0(qR/q0)
225
252
270
270
270
z(m)
0,5
1
1,5
2
2,5
z/B
0,5
1
1,5
2
2,5
L0(m)
1,55
2,6
3,4
3,85
4,2
X0(m)
0,55
0,8
1,1
1,4
1,65
L0-X0(m)
1
1,8
2,3
2,45
2,55
z+Df
1,5
2
2,5
3
3,5
(L0-X0)(z+Df)
25,95
62,28
99,48
127,16
154,4
FB(kN/m)
173,4
217,2
255,1
274,4
293,3
FS(P)=FB/T(N)
2,62
2,96
3,16
3,34
3,57
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
t
FS ( B )T( N )
( LDR ) f y

Beà daày thanh gia
cöôøng
t (mm)
3
T( N )
5
(2,5  10 )(0,65)
Lôùp gia cöôøng soá
1
2
3
4
5
1,22
1,36
1,49
1,52
1,52
Ta coù theå choïn chieàu daàylaøm vieäc thanh gia cöôøng cho taát caû caùc lôùp laø 1,6mm vaø chieàu
daày bò ræ seùt haøng naêm cuûa theùp galvani laø 0,025mm. Ñeå cho theùp coù tuoåi thoï laø 50
naêm, chieàu daày cuûa thanh gia cöôøng laø 1,6 + 0,025x50=2,85mm
Chieàu daøi thanh gia
cöôøng
Lmin (m)
Lôùp gia cöôøng soá
1
2
3
4
5
3,1
5,2
6,8
7,7
8,4
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
B=1m
Df =1m
0,5m
L=3,1m
L=5,2m
L=6,8m
0,5m
0,5m
0,5m
L=7,7m
L=8,4m
0,5m
z
x
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
  DAˆ B
4 sin 3 ( / 2)
AG2  r
3   sin 


2
4 0,353
 AG2  r
 0,826r
3 0,570
A
D
G1
H
G
cu
G2
M
B
4 2
2
AG1  r
r
3 2
3
r 2

M gt   sat
AG sin  0,33 sat r 3
4
4
r
r2
M ct  cu
r  cu  1,57cu r 2
2
2
 r2
r2
r2 r2
AG
 AG1  AG2 (  )
4
2
4 2

4 2

AG  r
 0,826(  0,5)r 
 6
4

M ct 1,57 cu
cu
FS 

 4,57
M gt 0,33  sat r
 sat H
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
A
D
d1
cu
H
M
T1
T2
T3
B
M ct
4,57cu
FS 

M gt  sat H   Ti di
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
A
E
cu
H

B
Tct
4cu
FS 

Tgt  sat H   Ti d i
d1
T1
T2
T3
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
Le
Lr(max)
450 + /2
C
A
L0
Maë
t tröôït
Vaû
i ñòa kyõthuaä
t
Lr
Sv
B
Neà
n cöù
ng
H
Choáng tröôït baèng væ taàm voâng - ÖÙng duïng vaøo ñöôøng vaøo caàu Xaùng
Hoùc Moân (1993)
taêng cöôøng oån ñònh cuûa maùi doác baèng væ choáng tröôït cho caùc coâng trình
ñaát ñaép cao trung bình nhö ñöôøng vaøo caàu, ñeâ, ñaäp nhoû, …Vaø öùng duïng
cuûa noù vaøo tính toaùn oån ñònh ñöôøng vaøo caàu Xaùng Hoùc Moân ( bôø phía
Cuû Chi), naêm 1993.
kt 
D
O
R
di
B
A
tneo
C
t
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
W
t AC R   t neo,i Lneo,i d i
WD
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
Phaûn aùp
Maët tröôït ghi nhaän cuûa ñöôøng vaøo caàu Xaùng
Hoùc Moân, bôø phía Cuû Chi
Væ taàm voâng
C
B
Phaûn aùp
A
tr
Vuøng neo
Baêng tröôït ñaõ xuaát hieän
tr
kt 
tp= tneo
(t r AC  t dd AB ) R   t neo,i Lneo,i d i
WD
kt min =1.21
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
Taïi ñaùy lôùp ñeäm toång aùp löïc do troïng löôïng baûn thaân ñaát neàn vaø taûi ngoaøi phaûi nhoû hôn khaû
naêng chòu taûi cuûa ñaát neàn töï nhieân taïi ñoä saâu naøy.
Theo QPXD 45-70
bt + z < Rtcz =m(Abztc + B(h+z)tc* + Dctc )
Hoaëc theo QPXD45-78
bt + z < RIIz =(m1m2/ktc)(AbzII + B(h+z)II* + DcII )
z=k0gl vôùi k0 : heä soá phaân boá öùng suaát theo chieàu saâu phuï thuoäc l/b vaø z/b (hoaëc 2z/b)
bz : beà roäng moùng tính ñoåi quy öôùc (aûo)
b  F  a2  a
z
z
vôùi a  l  b
2
trong ñoù l vaø b laø chieàu daøi vaø chieàu roäng cuûa moùng thieát keá.
Beà roäng ñaùy ñeäm caùt ñöôïc xaùc ñònh theo giaû thuyeát goùc truyeàn taûi trong neàn ñaát laø 300 :
bñc = b + 2h tg300
gl
hdc
bt
bdc
z
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
Composite geosynthetic
for use in clayey soils
Woven geotextile
(tensile reinforcement)
Non-woven geotextile
（drainage）
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
Backfill of nearly saturated clay
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
3) Three failure modes:
Cross-section exposed at its demolishing;
- lines 1 & 2; critical failure surfaces by the limit equilibrium stability
analysis without and with taking into account the pore pressure in cracks.
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
- R & L: total deformation by the rainfall test.
- Ra; deformation only in the last day of the rainfall test.
- K; similar data for Kami-Onda embankment.
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
-Three failure modes;
The safety factors for all these three failure modes should be
examined in design.
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
4) Despite the use of so-called very extensible reinforcement (i.e., a
non-woven geotextile), no failure plane and tension cracks in the
reinforced zones, as with Chiba No. 1 test embankment.
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
Reinforced Soil Wall
This reinforced soil wall was constructed in 1999 using Keystone
blocks with geogrid reinforcements near Sacramento, California.
This photo shows a lower row of
Keystone blocks, with the geogrid
reinforcement extending to the right
side.
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
Coarse sand is packed in and
around the blocks. The top
surfaces of the blocks must be
swept free of soil before the
next level of blocks can be
placed. Dowels are placed in
the small-diameter holes in the
blocks, and connect the upper
blocks to the lower blocks in
an overlapping sequence
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
Sheets of geosynthetic "geogrid" are the reinforcement for the soil
backfill. The front-end loader was used to place coarse sand / pea
gravel directly behind the keystone blocks (left side of photo) to act
as a drainage layer.
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
The geogrid is sandwiched
between the facing blocks, and
is hooked over the dowels that
connect the blocks.
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
A view of the exposed face of the wall as construction progresses.
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
The wall is stepped-back at this location. The white PVC pipes are drain
lines that connect to the drainage layer directly behind the blocks.
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
Geogrids are being laid out over a completed row of blocks. The two
scrapers (earth-moving equipment in the upper left) are placing fill soils
behind the geogrids
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
The backhoe in the background spreads the fill materials out over the
geogrid. Care must be taken not to damage the geogrids by driving
equipment over the unprotected grid. Wood stakes are used to stretch
the geogrid flat and hold it in place while the soil is placed over it.
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
Another row of blocks is being placed, with the geogrid sandwiched
between the overlapping blocks. The front-end loader is placing the
drainage layer in the background.
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
1996 - 1997 Mercer Lecture
(Revised, August 2001)
Geosynthetic-Reinforced Soil
Retaining Walls
as Important Permanent Structures
F.Tatsuoka
Department of Civil Engineering, University of Tokyo
M.Tateyama
Railway Technical Research Institute of Japan Railways Group
T.Uchimura
Department of Civil Engineering, University of Tokyo
J.Koseki
Institute of Industrial Science, University of Tokyo
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
Rapid transit trains running
on geogrid-reinforced soil
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
Geogrid
GRS-RWs having a full-height rigid facing
constructed by the staged construction procedure
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
-now supporting railway and highway embankments
with a total wall length more than 65 km; and
- one of the standard wall construction procedures
for railways and highways in Japan, replacing the conventional
wall construction procedures.
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
Staged construction - 1;
- the wall is first constructed with a help of gabions filled
with crushed gravel; and
DRAINAGE
1) LEVELLING PAD
3) BACKFILL AND
COMPACTION
5) COMPLETION OF
WRAPPRED AROUND
WALL
GRAVEL GABION
GEOTEXTILE
2) PLACING GEOTEXTILE
AND GRAVEL GABION
4) SECOND LAYER
6) CASTING-IN-PLACE
OF RC FACING
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
A 5 m-high wall before casting-in-place a FHR facing
DRAINAGE
1) LEVELLING PAD
3) BACKFILL AND
COMPACTION
5) COMPLETION OF
WRAPPRED AROUND
WALL
GRAVEL GABION
GEOTEXTILE
2) PLACING GEOTEXTILE
AND GRAVEL GABION
4) SECOND LAYER
6) CASTING-IN-PLACE
OF RC FACING
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
Staged construction - 2;
- Then, after the deformation of the backfill and supporting
ground has taken place, a full-height rigid facing is cast-inplace directly on the wrapped- around wall.
DRAINAGE
1) LEVELLING PAD
3) BACKFILL AND
COMPACTION
5) COMPLETION OF
WRAPPRED AROUND
WALL
GRAVEL GABION
GEOTEXTILE
2) PLACING GEOTEXTILE
AND GRAVEL GABION
4) SECOND LAYER
6) CASTING-IN-PLACE
OF RC FACING
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
Permanent critical civil engineering
structures
made of cement-mixed soil
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
Ground
(1) piles
Inherent problems with conventional bridge abutments
(the numbers imply the construction sequence)
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
(2) RC abutment
Ground
(1) piles
Inherent problems with conventional bridge abutments
(the numbers imply the construction sequence)
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
(2) RC abutment
(3) Backfill
Ground
(1) piles
Inherent problems with conventional bridge abutments
(the numbers imply the construction sequence)
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
(4) Displacement
of the abutment
due to the earth pressure
(2) RC abutment
(3) Backfill
(4) Earth pressure
Ground
(4) Settlement and lateral
flow of ground; and
associated negative friction
(1) piles and bending of the piles
Inherent problems with conventional bridge abutments
(the numbers imply the construction sequence)
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
(4) Displacement
of the abutment
due to the earth pressure
As the abutment and piles
have to resist without
exhibiting large displacement
against these earth pressure
and ground movements (4),
they have to be very massive
and strong.
(2) RC abutment
(3) Backfill
(4) Earth pressure
Ground
(4) Settlement and lateral
flow of ground; and
associated negative friction
(1) piles and bending of the piles
Inherent problems with conventional bridge abutments
(the numbers imply the construction sequence)
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
(5) Bridge girder
(4) Displacement
of the abutment
due to the earth pressure
As the abutment and piles
have to resist without
exhibiting large displacement
against these earth pressure
and ground movements (4),
they have to be very massive
and strong.
(2) RC abutment
(3) Backfill
(4) Earth pressure
Ground
(4) Settlement and lateral
flow of ground; and
associated negative friction
(1) piles and bending of the piles
Inherent problems with conventional bridge abutments
(the numbers imply the construction sequence)
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
(1) Cement-mixed soil
(1) Backfill
Ground
Advantages of cement-mixed soil bridge abutments
(the numbers imply the construction sequence)
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
(1) Cement-mixed soil
(1) Backfill
Ground
(2) Settlement and lateral
flow of ground
Advantages of cement-mixed soil bridge abutments
(the numbers imply the construction sequence)
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
(3) A FHR facing
(1) Cement-mixed soil
(1) Backfill
Connected
As the FHR facing is constructed
after the deformation of ground
and backfill has taken place,
a massive RC abutment and deep
piles become unnecessary.
Ground
(2) Settlement and lateral
flow of ground
Advantages of cement-mixed soil bridge abutments
(the numbers imply the construction sequence)
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
(4) Bridge girder
(3) A FHR facing
(1) Cement-mixed soil
(1) Backfill
Connected
As the FHR facing is constructed
after the deformation of ground
and backfill has taken place,
a massive RC abutment and deep
piles become unnecessary.
Ground
(2) Settlement and lateral
flow of ground
Advantages of cement-mixed soil bridge abutments
(the numbers imply the construction sequence)
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
Combined use of compacted cement-mixed gravel and geotextilereinforcement
Bridge
Usual soil embankment
Anchoring
cement-mixed gravel
Abutment
Geotextile
No increase in the earth pressure during seismic loading
 Simple, no need for a pile foundation.
Prediction of long-term deformation !
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
Asphalt pavement
about 5.0m
0.8m
4.0m
1.6m
sandy gravel
Estimated failure surface
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
Asphalt pavement
about 7.0m
5.0m
0.6m 3.6m
0.7m
90°
sandy gravel
Estimated failure surface
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
Asphalt pavement
about 7.0m
5.0m
0.6m 3.6m
0.7m
90°
sandy gravel
Estimated failure surface
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
Construction Procedure of RADISH Anchor
Auger
Guide cone
[Setting the FRP rod]
Normal rotation
FRP rod
Mixing blade
Stabilizing blade
[Drilling and mixing]
Reversed rotation
Fastening cone
Reversal of rotation
and withdrawal
core rod
[End of work]
Cement slurry
Cement-mixed soil
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
View of work in progress, Ikebukuro
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
Anchor body retrieved from the slope
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
Large diameter nailing versus ground anchor
Potential Slip surface
5.6m
Tension force
H‐beam
RADISH
Anchor
RADISH Anchor
H‐beam
Large axial
force
Earth Anchor
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN
BAØI GIAÛNG A Pr.Dr. CHAÂU NGOÏCAÅN