Geoscience Reference
In-Depth Information
4.2. EFFECT OFFINES CONTENT INPOST-LIQUEFACTION
SHEAR BEHAVIOR
Figure 8.24(a) and (b) shows deviatoric stress or pore-pressure versus axial strain rela-
tionships obtained in post-cyclic undrained monotonic loading tests for RS1 and RS3,
respectively,ofdifferentfinescontenthavingrelativedensityofabout50%.Inpriorcyclic
loadinghistory,allspecimensattainedalmost100%pore-pressurebuildupandmorethan
10% DA axial strain. In the initial stage of monotonic loading, stress increases gradually
with increasing strain reflecting softened shear stiffness due to preceding cyclic loading.
The induced stress is much higher for RS3 than RS1 due to the difference in particle
gradation as explained before. In both RS1 and RS3, however, increasing fines content
tends to dramatically reduce the stress recovery after liquefaction. In Figure 8.25(a) and
(b), post-liquefaction residual strengths defined as the deviatoric stresses at 20% axial
strain are plotted versus fines content for RS1 and RS3, respectively, with
D
r
30%,
50% and 70%. Although the absolute strength shown in the figures with solid symbols
=
q Fc=0%
PWP Fc=0%
q Fc=5%
PWP Fc=5%
q Fc=10%
PWP Fc=10%
q Fc=20%
PWP Fc=20%
q Fc=30%
PWP Fc=30%
0.1
(a)RS1+Fines
Dr~50%
0.05
0
−0.05
σ
c
'=0.098 MPa
0
5
10
15
20
Axial strain ε (%)
(b)RS3+Fines
Dr~50%
1
0.5
0
−0.5
σ
c
'=0.098 MPa
0
5
10
15
20
Axial strain ε (%)
Fig. 8.24. Stress-strain curves in post-liquefaction tests for RS1 and RS3
withdifferent fines content
