correlating, v s , q c and cyclic resistance of a silty sand through laboratory calibration tests
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Correlating, Vs, qc and Cyclic Resistance of a Silty Sand through
Laboratory Calibration Tests
An-Bin Huang, Yao-Tao Huang, and Yu-Chen KuoDepartment of Civil Engineering National Chiao Tung University Hsin Chu, TAIWAN
Effects of nonplastic fines on CRR
Higher CRR ? Lower CRR ? Depends… ?
Effects of nonplastic fines on qc
Variation of qc under the same void ratio and stress conditions as the fines content changes ?
What void ratio ?
Seed and de Alba (1986)
0 1 0 2 0 3 0 4 0 5 0F in es co n ten t, %
0
1 0
2 0
3 0
4 0
5 0
qcl
N
B ase d o n re s id u a l s tren g th (Ish ih a ra e t a l., 1 9 9 1 )B ase d o n c y c lic s tre n g th (S e ed & D e A lb a , 1 9 8 6 )
Ishihara (1993)
0 1 0 2 0 3 0 4 0 5 0F in e s co n te n t, %
0
2 0
4 0
6 0
8 0
1 0 0
qcl
N
R e co m m e n d e d fo r d es ig n
(S ta rk a n d O lso n , 1 9 9 5 )
S ee d a n d D e A lb a (1 9 8 6 )
Stark and Olson (1995)
Effects of nonplastic fines on Vs
Variation of Vs under the same void ratio and stress conditions as the fines content changes ?
What void ratio ?
Andrus and Stokoe (2000)
Youd et al. (2001)
…The CRR corrections based on fines contents should be used with engineering judgment and caution…
Liquefaction potential mapping
qc Vs
Laboratory calibration tests
CPT calibration tests Vs measurements with bender elemen
ts Cyclic triaxial tests Use Mai Liao Sand (MLS), a typical silt
y fine sand in Central Western Taiwan
1 .0 0 0 0 .1 0 0 0 .0 1 0 0 .0 0 1S iev e o p e n in g , m m
0
1 0
2 0
3 0
4 0
5 0
6 0
7 0
8 0
9 0
1 0 0
Perc
ent f
iner
, %
H y d ro m e te r te s tS iev e an a ly sis
Coarse grains Fine grains
10 1 00 1 0 00 1 0 0 00 1 0 0 0 00log p' , kP a
0 .5
0 .6
0 .7
0 .8
0 .9
1 .0
Voi
d ra
tio ,
e
Y a m am u ro et a l. ( 1 99 6 )
M L SIn itia l D r = 2 4 %
I nitia l D r = 3 8 %
I nitia l D r = 6 2 %
Q u ar tz sa ndL o o se
M e d ium
CPT calibration tests in MLS
FC = 0%, 15%, 30% and 50% Dro = 50%, 70% and 85% ’v = 100, 200 and 300 kPa K = 0.5, 1 and 2
The calibration chamber
Sample preparation
Dry deposition Saturated under a backpressure or dry Stresses applied in steps follow the
designated K value
0 1 2 3 4 5q c, M P a
0 1 2 3q c, M P a
0
1 0 0
2 0 0
3 0 0
4 0 0
5 0 0
6 0 0
7 0 0
8 0 0
Dep
th o
f pen
etra
tion,
mm
0 5 1 0 1 5 2 0q c , M P a
F C = 1 5 % d ry (9 7 -0 5 0 1 -D -H ) sa t. (9 7 -0 1 2 0 -S -S )
F C = 3 0 % d ry (9 9 -1 0 2 3 -D -H ) sa t. (9 8 -0 1 2 2 -S -S )
F C = 5 0 % d ry (0 0 -0 5 1 7 -D -S ) sa t. (9 9 -1 2 3 0 -S -S )
0 1 0 0 2 0 0 3 0 0(q c-p )/p '
0 .4
0 .6
0 .8
1 .0
1 .2
0 .5
0 .7
0 .9
1 .1
e c
T ic in o (A lm eid a e t a l., 1 9 9 1 )Q u iou (A lm eid a e t a l., 1 9 9 1 )M L S , F C = 0%M L S , F C = 15 %M L S , F C = 30 %M L S , F C = 50 %
c
C
a
h
C
a
v
a
c eCPP
CPq
30
2
exp21
21
2
230 exp
CC
v
a
a
cc
C PPq
eCKC
Ncq 1 = cC eCKC 30 exp2
n = C1+C2
Fines content
C0 C1 C2 C3
% n = C1+C2
0 383 0.03 0.42 -2.02 0.9415 236 0.23 0.44 -1.63 0.9630* 26 0.02 0.77 -1.04 0.95
50+ 316 0.69 0.11 -6.05
0.93
0 5 1 0 1 5 2 0 2 5 3 0
M easu red q c, M P a
0
5
1 0
1 5
2 0
2 5
3 0
Com
pute
d q c
, MPa
F C , %01 53 05 0
0 1 0 2 0 3 0 4 0 5 0F in es co n te n t, %
0
1
2
3
4
Soil
beha
viou
r typ
e in
dex,
I C
Z o n e 2 : o rg a n ic so ils -p ea ts
Z o n e 3 : c lay to s ilty c la y
Z o n e 4 : c la y e y s ilt to s ilty c la y
Z o n e 5 : s ilty sa n d to sa n d y s ilt
Z o n e 6 : c lea n san d to s ilty sa n d
Z o n e 7 : sa n d to g ra v e lly san d
R ec o m m en d e d g en e ra l c o rre la tio n
Effects of fines on in MLScrefc qq
Reference state ofdensity
FC%
K=0.5 K=1.0
0.5 1.0 2.0 0.5 1.0 2.0
ec=0.6715 0.68 0.79 0.91 0.68 0.79 0.9230 0.08 0.10 0.13 0.10 0.13 0.1650 -- -- -- 0.04 0.06 0.07
ec = 0.73~79
15 0.78 0.91 1.05 0.79 0.92 1.0630 -- -- -- -- -- --50 -- -- -- -- -- --
ec =0.9515 1.21 1.41 1.63 1.22 1.42 1.6530 -- -- -- -- -- --
av P av P
Cyclic triaxial tests
Sample preparation by wet tamping in 4 layers
K = 1 Saturated under a back pressure ’v = 100 kPa Bender element Vs measurement on th
e same triaxial specimen
1 1 0 1 0 0 1 0 0 0N v a lu e
0 .1
0 .2
0 .3
0 .4
0 .5
0 .6
CR
R
F C ,% ec C R R0 0 .9 7 0 .1 90 0 .9 3 0 .2 20 0 .8 5 0 .3 50 0 .8 0 0 .4 50 0 .7 3 0 .5 41 5 0 .7 3 0 .4 51 5 0 .8 0 0 .3 43 0 0 .8 1 0 .1 63 0 0 .7 3 0 .2 2
1 2 0 1 4 0 1 6 0 1 8 0 2 0 0V s, m /s
0 .7
0 .7 5
0 .8
0 .8 5
0 .9
0 .9 5
e c
F C , % 'c , k P a
0 1 0 01 5 1 0 03 0 1 0 0
0 .6 0 .7 0 .8 0 .9V o id R a tio , e
8
1 2
1 6
2 0
2 4
2 8
(K2) m
ax
F C < 5 %F C = 1 5 %F C = 3 0 %F C = 5 0 %
0 5 0 1 0 0 1 5 0 2 0 0q c 1 N
0
0 .1
0 .2
0 .3
0 .4
0 .5
0 .6
Cyc
lic st
ress
or r
esis
tanc
e ra
tio, C
SR o
r CR
RC
RR L a b . c o rre la tio n
F C , %01 53 0
C le a n sa n d R o b e rtso n a n d W rid e (1 9 9 8 )
P ro je c te d c le a n M L SF C = 0 to 1 5 %
Tentative due to differences in sample preparation methods
0 1 0 2 0 3 0 4 0 5 0F in es c o n ten t, %
0
1 0
2 0
3 0
4 0
5 0
6 0
qcl
N
B ased o n re s id u a l s tren g th (Ish ih a ra e t a l., 1 9 9 1 )B ased o n cy c lic s tre n g th (S eed & D e A lb a , 1 9 8 6 )M L S ca lib ra tio n
0 1 0 2 0 3 0 4 0 5 0F in e s co n te n t, %
0
2 0
4 0
6 0
8 0
1 0 0
qcl
N
M L S c a lib ra tio n
R e c o m m e n d e d fo r d es ig n
(S ta rk a n d O lso n , 1 9 9 5 )
S e ed a n d D e A lb a (1 9 8 6 )
0 1 0 0 2 0 0 3 0 0S h ea r w a v e v e lo c ity , V s1 , m /s
0
0 .1
0 .2
0 .3
0 .4
0 .5
0 .6
Cyc
lic s
tress
or r
esis
tanc
e ra
tio, C
SR o
r CR
R
L a b . c o rre la tio n F C , %
01 53 0
3 52 0
5
A n d ru s an d S to k o e , 2 0 0 0
F C , %
Concluding remarks
The current qc and Vs methods too conservative? Not necessarily, due to differences in Shearing mode K values
Fines affect CRR and Vs through soil structure, grain characteristics and compressibility
Drainage effects are much more significant to qc
When using CPT for liquefaction potential assessment in MLS
Make adjustment based on t50 from pore pressure dissipation test or change of qc after pore pressure dissipation
But not IC
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