Environmental Engineering Reference
In-Depth Information
120
100
80
SWCC fitting parameters
60
a f n f m f ψ r (kPa)
130 2.2 1.5 2000
40
20
Thu et al. (2007c) data
SWCC using
Fredlund and Xing (1994)
0
0.1
1
10
100
1000
10,000
Soil suction, kPa
Figure 12.25 SWCC data for compacted kaolin in terms of degree of saturation versus soil
suction (after Thu et al., 2007a).
0.6
0.5
0.4
0.3
0.2
0.1
Thu et al. (2007c) data
Fredlund and Xing (1994) with C r
1
=
0.0
0.1
1
10
100
1000
10,000
Matric suction ( u a - u w ), kPa
Figure 12.26 SWCC for compacted kaolin in terms of volumetric water content versus soil
suction (after Thu et al., 2007a).
apparatus. The soil was a mixture of kaolin clay (15%)
and silt (85%) compacted to the maximum dry density
of 1350 kg/m 3 at an optimum water content of 22%. All
specimens were statically compacted in 10 layers of equal
thickness of 10 mm. The SWCC of the soil was obtained by
desaturating the soil under zero net vertical pressure. The
degree of saturation versus soil suction SWCC is shown
in Fig. 12.25 along with the best-fit SWCC parameters
for the Fredlund and Xing (1994) equation. The plot of
volumetric water content versus soil suction is shown
in Fig. 12.26.
The shear strength parameters for the saturated compacted
kaolin were φ =
Table 12.4 Parameters for Shear Strength Equations
for Compacted Kaolin Clay
Equations
Soil Parameters
Oberg and Sallfors (1997) SWCC, S
Fredlund et al. (1996)
κ
=
0 . 531, θ s =
0 . 51, SWCC
Vanapalli et al. (1996b)
θ s =
0 . 51, θ r =
0 . 140 , SWCC
Goh et al. (2010)
n d =
2 . 908, ψ aev =
47 kPa,
PI, SWCC
31 . 1 and c =
0 kPa. Soil parameters
from the SWCC that are required for the estimation of shear
strength with respect to soil suction are listed in Table 12.4.
The measured shear strength data along with estimations
of the shear strength envelope for the compacted kaolin are
shown in Fig. 12.27. The measured shear strength increases
with matric suction in a nonlinear manner. The equations by
Goh et al., (2010) and Fredlund et al., (1996) provide estima-
tions that are quite close to the measured shear strengths. The
estimation procedures based on the SWCC appear to reflect
 
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