Tuyển tập Hội nghị Khoa học thường niên năm 2015. ISBN: 978-604-82-1710-5
326
ANALYSIS OF LIQUEFACTION POTENTIAL
OF RIGHT RED RIVER DYKE, K73+500-K74+100
Nguyen Hong Nam1, Nguyen Thi Khanh Hoa1
Thuy loi University, email: hongnam@wru.vn, email:hoantk1nk@wru.vn
1. INTRODUCTION
The right Red river dyke has a crucial
role to protect Hanoi capital from flooding.
In some dyke locations, however, the
foundation consists of shallow fine sandy
layers which can easily be liquefied during
strong earthquakes.
Hanoi city is situated in the region of Red
river-Chay river fault where some strong
earthquakes with maximum magnitudes
of 5.5 degree have occurred in the
past. Although Hanoi is now in the silent
period, but the seismic activities may
increase in the future (Xuyen, 2004).
Liquefaction caused by strong
earthquakes has seriously damaged river
dykes in the world in some typical failures
such as excess settlement and instability.
Soil liquefaction describes the behavior of
saturated sandy soils that, when undrained
loaded, suddenly suffer a transition from a
solid state to a liquefied state. The excess
porewater pressure builds up causing soil
strength decreased, and finally the soil
becomes liquefied.
To investigate the liquefaction potential of
soil, the simplified procedure (Seed and
Idriss, 1971; Youd el al., 2001) using the
insitu soil tests such as SPT, CPT has been
applied extensively.
This study aims at evaluating the
liquefaction potential of dyke foundation of
right Red river dyke, from K73+500 to
K74+100 based on the geotechnical
investigation data (WRU, 2015).
2. EVALUATION OF DYKE LIQUEFACTION
POTENTIAL
The simplified procedure (Seed and Idriss,
1971) suggests the factor of safety against
liquefaction determined as below:
FS = (CRR7.5/CSR)MSF (1)
where CSR = calculated cyclic stress ratio
generated by the earthquake shaking;
CRR7.5 = Cyclic resistance ratio for magnitude
7.5 earthquakes; MSF = magnitude of
scaling factor.
DC1
DC2
DC3
DC4
DC5
DC6
Bb¸o
KÌ
Km 74 ®ª HH
T-êng kÌ ®¸
T-êng kÌ ®¸ Bb¸o
§- êng bª t«ng
Bb¸o
Häng cøu ho¶
Br«
V-ên
Ngâ bª t«ng
T«n
T«n
S©n
S©n
B3 B4
B3
NS©n
B3
B3
Br«
Ng¸ch 1/28 phè Thuý LÜnh (bª t«ng)
Br«
Br«
B2
Br«
S©n
N
S©n
N
V-ên
BBr«
Br«
B3
S©n
B3
B
NT«n
B3
B3
Br«
B3
B3
N
B2
Br«
V-ên
Br«
B3
S©n
T«n
Ngâ bª t«ng
B·i vËt liÖu
S©n
Tre
Ngâ bª t«ng
B3
S©n
BËc thang T«n
Br«
Br«
N
B2
N
B3
B2
S©n
V-ên
B4
C«ng ty Th¨ng L ong
B
T«n
S©n bª t«ng
Ng¸ch 1/48 phè Thuý LÜnh (bª t«ng)
T«n
L¸ n t ranh
T«n
S©n bª t«ng
§ Êt
T«n
T«n
B4
T«n
Ngâ bª t«ng
B3
V-ên
B2
B3
T«n
B3
NB
B3
B3
B
§ i Ön t h ê
S©n
Bb¸o
V-ên
Hoang
T«n
T«n
S©n
S©n ch¹t
Ng¸ch 1/56 phè Thuý LÜnh (bª t«ng)
B
B3
C«ng ty thiÕt
bÞ gi¸o dôc
B2 B4
B3
B4
T«n
T«n
S©n Br« Br«
B3
L¸ n t ranh
Tr¹m bi Õn ¸p
Bb¸o Bb¸ o
Bb¸o
Tre
S©n ch¹t
Tr¹m bi Õn ¸p
§- êng ®¸ lÉn ®Êt
Cèng bi
R·nh
C«ng ty TNHH Hµ Thµnh
B·i vËt liÖu
B·i vËt liÖu
T«n
T«n
B·i vËt liÖu
B2
S©n cá hoang
C«ng ty xuÊt khÈu B¶o ViÖt
T«n
Bª t«ng
Tr¹m bi Õn ¸p
S©n cá hoang
Tr¹m bi Õn ¸p
T«n
S©n
T«n
Thïng
T«n
S©n bèc sÕp xi m¨ng
C©y t ¹ p
Gi Õn g
GiÕng gi¶m ¸p
GiÕng gi¶m ¸p
GiÕng gi¶m ¸p
V-ên chuèi
§- êng bª t«ng
§- êng bª t«ng
R·nh n- í c
R·nh n- í c
R·nh n- í c
Tre
Bb¸o
T-êng kÌ ®¸
T-êng kÌ ®¸
M¸ n g x ©y
B¨ n g k Ðt
Thïng
V-ên chuèi
V-ên x i
V-ên chuèi
V-ên r au
V-ên x i
V-ên quÊt
V-ên r au
V-ên r au
L¸ n t ranh
L¸ n t ranh
V-ên quÊt
V-ên quÊt
L¸ n t ranh
L¸ n t ranh
V-ên r au
V-ên quÊt
V-ên chuèi
V-ên chuèi
M¸ng
M¸ng
L¸ n t ranh
V-ên r au
T r ô s ¾t
Bb¸o
CÇu Thanh Tr×
KÌ
§- êng ®¸ lÉn ®Êt
Bb¸o
Bb¸o
Khu ®-êng ®¸ lÉn ®Êt
BÖ r ö a x e C«ng ty TNHH V iÖt V-¬ng
T«n
C©y x¨ng
BÓ x ¨ n g
BÓ x ¨ n g
T«n
T«n
T«n
S©n bª t«ng V-ên x i
§- êng ®¸ lÉn ®Êt
§i r a s«ng Hång
§- êng ®¸ lÉn ®Êt
§- êng bª t«ng
§i r a s«ng Hång
M¸ng ngÇm
Mè T7B
Mè T7A
Mè H7
Mè H8
Mè T8
T«n
Bª t«ng
Bª t«ng
R·nh R·nh
V-ên c ©y trøng c¸
B1
§ i Õm
B1
Bb¸o
Dèc bª t«ng
Dèc bª t«ng
§- êng bª t«ng
T ¾m
T«n
N
Br«
Br«
Tre
S©n bª t«ng
B·i vËt liÖu
Bb¸o
T«n
S©n
B
T«n
T«n
Tr¹m trén bª t«ng
S©n bª t«ng
S©n vËt liÖu
B1
C«ng ty th- ¬ng m¹i Minh T ©m
Tr¹m c©n ®iÖn tö
Br«
T«n
T«n
Tre
Tre
Tre
Br«
Br«
Tre
GiÕng gi¶m ¸p
GiÕng gi¶m ¸p
GiÕng gi¶m ¸p
Gi Õn g
MÐp t r e
V-ên chuèi Tre
Tre
Tre
GiÕng gi¶m ¸p
Tre
Tre
Cá hoang
§Ìn
§Ìn
§Ìn
§Ìn
§Ìn
§Ìn
Bb¸o
§Ìn
§- êng bª t«ng
§- êng bª t«ng
§- êng bª t«ng
Hè x ©y
V-ên chuèi
V-ên chuèi
V-ên r au
V-ên chuèi
§Ìn
§Ìn
§Ìn
§Ìn
§Ìn
R·nh n- í c
R·nh n- í c
§- êng bª t«ng
§- êng bª t«ng
§- êng bª t«ng §- êng bª t«ng
T«n
Br«
T«n
S©n bª t«ng
M¸ n g x ©y
Chuèi
Chuèi
T«n
T«n
BÓ
T«n
§ª H ÷u Hång (nhùa)
§i U BND ph- êng L Ünh Nam
§i cÇu Thanh Tr×
B·i coi xe
§iÓm göi cao ®é G dÊu (+)
S¬n ®á t¹i ®Ønh cét K m74 ®ª H÷u Hång
H = +14.812m
Lan can
Lan can
Lan can
Tre
V-ên r au vµ chuèi
§ª H ÷u Hång (nhùa)
§ª H ÷u Hång (nhùa)
§ª H ÷u Hång (nhùa)
§ª H ÷u Hång (nhùa)
Tre
Tre
Tre
Tre
Tre
Tre
Tre
Tre
Tre
Tre
Tre
Tre
V-ên chuèi
C©y t ¹ p
C©y t ¹ p
C©y t ¹ p
V-ên c ©y trøng c¸
V-ên x i
V-ên r au vµ chuèi
V-ên chuèi
V-ên r au
V-ên quÊt
V-ên quÊt
V-ên quÊt
V-ên r au
V-ên r au
V-ên r au
V-ên r au
V-ên r au
V-ên r au
V-ên r au
V-ên r au
V-ên r au
V-ên r au
V-ên r au
V-ên r au
V-ên r au
Tre
Tre
Tre
Tre
Tre
Tre
Tre
Tre
Tre
Tre
Tre
Tre
T-êng kÌ ®¸
HK9
HK7
HK8
HK1
HK6
HK4 HK5
HK2 HK3
CN1
CN2
CN3
GiÕng gi¶m ¸p
MC102
MC101
N
S©n
Fig.1. Layout of boreholes
For clean-sand (Youd et al., 2001):
CRR7.5=
1 60
1 60
(N )
1
34 ( N ) 135
++
−
+
2
1 60
50 1
200
[10( N ) 45] −
+
(2)
Tuyển tập Hội nghị Khoa học thường niên năm 2015. ISBN: 978-604-82-1710-5
327
+12,0
+10,0
+8,0
+6,0
+4,0
+2,0
0,0
-2,0
-4,0
-6,0
-8,0
-10,0
-12,0
-14,0
-16,0
-18,0
-20,0
-22,0
-24,0
-26,0
-28,0
-30,0
-32,0
-34,0
-36,0
-38,0
-40,0
0,2
3,93,9
10,5
10,5
10,5
15,7
20,0
38,538,5
40,040,0
15,7
17,8
9
8
6
5
6
9
9
10
11
12
20
25
24
23
20
21
28
29
30
28
Hk9
+10,79
K74+100
0,5
1,81,8
5,0
11,211,211,2
16,3
18,0
34,734,734,7
36,6
40,140,140,1
50,0
19
12
8
7
7
12
14
8
18
19
21
16
24
24
25
23
19
21
15
29
30
34
30
33
37
43
Hk8
+12,00
88,9
K74+100
0,4
1,8
1,8
1,8
4,4
8,58,5
16,3
19,119,1
26,5
36,236,2
39,3
40,0
3,2
13,5
16,3
32,1
33,5
12
8
7
8
10
11
13
9
13
12
5
6
8
14
7
14
41
28
49
44
HK7
+6,77
60,8
K74+100
1A 1B
1C 1D
2A
2C
3A
3B
4A
4B
4D
4E
1A
1B
1D
2A
2C 2D
3A
3B
3D
4A
4B
4D
4E
Borehole name
B.H. elevation (m)
Distance (m)
Station
Rev etment wal l
Asphant road Rev etment wal l
Bamboo Bamboo
Bamboo Mortar wallConcr ete yar d
Concr ete r oad
Concr ete y ard
Corrugated iron houses
B3
Yard
Mortar wall
Garden
12,0
12,3
13,6
14,5
Geo t ec h nic al Cr o ss sec t io n 3-3 (K74+100)
Fine sand,
medium size
Fine sand,
Coarse sand
(medium size sand
where
is the SPT blow count
normalized to an overburden pressure of
approximately 100 kPa and a hammer energy
ratio or hammer efficiency of 60%.
2.24 2.56
w
MSF 10 / M=
(3)
where Mw is earthquake magnitude.
The critical stress ratio, induced by the
design earthquake, CSR was calculated as:
cyc max vo d
vo vo
a
CSR 0.65 r
' g'
τσ
σσ


= = 



(4)
where amax = peak horizontal ground
acceleration (PGA); g = gravitational
acceleration; σvo and σ’vo = total and
effective vertical overburden stresses,
respectively, at depth z (m) from ground
surface. rd=stress reduction coefficient.
0.5 1.5
d0.5 1.5 2
(1.000 0.4113z 0.04052z 0.001753z )
r(1.000 0.4177z 0.05729z 0.006205z 0.001210z )
− ++
=− +− +
(5)
The soil investigation was implemented at
the right Red river dyke, segment: K73+500 -
K74+100 (WRU, 2015). Nine boreholes
(HK1 to HK9) were drilled into the dense
sand with the depth of maximum 50m
(Fig.1). Fig.2: Geotechnical
cross section 3-3
(K74+100).
The soil strata from the ground surface
consists of the following layers (Fig.2):
1A (concrete, asphalt); 1B (made soil); 1C
(clayey soil);1D (made soil); 2A (clay, sandy
clay);2C (sandy clay); 2D (clayey sand, silty
sand);3A; 3B ; 3C (medium size sand with
some gravel, medium dense–dense); 3D
(clay, sandy clay, somewhere with sand); 4A
(Clay, sandy clay, with some gravel); 4B
(clayey sand); 4C (medium size sand, small
size particle, somewhere with gravel,
medium dense); 4D (medium size sand,
somewhere with fine sand, medium dense-
dense); 4E. The SPT work was conducted in
all boreholes following TCVN 9351:2012
standard. Results of SPT-N distribution with
borehole depth are shown in Fig.3.
The evaluation of liquefaction potential for
each borehole was implemented using
simplified procedure (Seed and Idriss, 1971).
The elevation of water table in nine
boreholes varied between 0.01m to 1.99m.
Note that the water level at the river side was
smaller than that in
the field side. The
calculation was
implemented with
two proposals of
return periods of 475
years (amax=0.13g)
and 2475 years (amax=0.21g) at the project
area. The PGA values were deduced from the
seismic analysis applied to the project area
(Son, 2014). In addition, the amax =0.1047g at
the site with a return period of 475 years by
TCXDVN 375- 2006 was also employed to
the analysis.
3. RESULTS AND DISCUSSION
Figure 3 shows the factors of safety
against liquefaction by eq. (1) with the depth
below ground surface for nine boreholes with
three PGA values as above mentioned.
It can be seen from most boreholes that,
the factors of safety fall below unity within
the depth of less than 15m from the ground
surface, except borehole HK7. The possible
reason could be due to the limits of
simplified procedures. The sandy soils of 2C,
2D, and 3A could be liquefied.
Tuyển tập Hội nghị Khoa học thường niên năm 2015. ISBN: 978-604-82-1710-5
328
Fig.3: Factors of safety against liquefaction at boreholes HK1 to HK9.
When the PGA increased, the factor of
safety against liquefaction decreased.
Note that the water level measured during
the surveying time was not the dangerous
case when the water level rises up to the
ground surface during flood season. In
addition, the effect of fine content was
neglected due to its small percentage.
4. CONCLUSION
The right Red river dyke, K73+500-
K74+100 is a weak segment where its
foundation consists of shallow fine sand layers
3A, 3B.
The evaluation of liquefaction potential of
foundation soils by simplified method (Seed
and Idriss, 1971) with SPT data revealed that
the segment K73+500-K74+100 could be
liquefied when subjected to strong earthquakes
(amax=0.13g and 0.21g).
The analysis of liquefaction potential and
the mapping the liquefaction zone of Red
river dike foundation should be properly
considered in the design, planning and
maintenance of the river dykes.
5. REFERENCES
[1] Son L.T. (2014). Calculation of PGA,
acceleration time history for Hanoi dyke
with return periods of 475 and 2475 years,
Report No.2.1, State project No.
KC.08.23/11-15 (in Vietnamese).
[2] Seed, H. B., & Idriss, I. M. (1971).
Simplified procedure for evaluating soil
liquefaction potential. J. Geotech. Engrg.
Div., ASCE, 97(9), 1249–1273.
[3] TCXDVN 375-2006. Design of structures
for earthquake resistance (in Vietnamese).
[4] TCVN 9351:2012. Soils - Field testing method
- Standard penetration test (in Vietnamese).
[5] Youd, T. L., et al. (2001). Liquefaction
resistance of soils: Summary report from
the 1996 NCEER and 1998 NCEER/NSF
workshops on evaluation of liquefaction
resistance of soils. J. Geotech. Geoenviron.
Eng., ASCE, 127(10), 817–833.
[6] Xuyen, N.D. (2004). Earthquake prediction
and ground motion in Vietnam, State funded
project, final report. (in Vietnamese).
[7] WRU (2015). Geotechnical investigation
report, right Red river dyke, K73+500-
K74+100 (in Vietnamese).