Shear Strength Applications in Plastic and Limit Equilibrium - Unsaturated Soil Mechanics in Engineering Practice - page 607

120

D. G. Fredlund et al. (1996)

100

80

Goh et al. (2010)

60

40

Oberg and Sallfors (1997)

20

Vanapalli et al. (1996b)

0

0 50 100 150 200 250 300

Matric suction ( u a - u w ), kPa

Figure 12.27 Comparison of estimations of shear strength from various proposed equations and
measured data for compacted kaolin (after Thu et al., 2007a).

60

50

40

30

20

10

Thu et al. (2007a) data
Fredlund and Xing (1994) with C r

= 1

0

0.01 0.1 1 10 100 1000 10,000

Matric suction ( u a - u w ), kPa

Figure 12.28 SWCC for compacted kaolin clay in terms of volumetric water content versus
soil suction when net confining pressure is 10 kPa (after Thu et al., 2007a).

quite well the flattening of the strength envelope at higher
suctions.

Table 12.5 Soil Parameters for Shear Strength
Equations for Compacted Kaolin Clay

12.2.5.3 Data on Compacted Kaolin When Measuring
Volume Change (Thu et al., 2007a)
Thu et al. (2007a) provided another set of shear strength results
on compacted kaolin using a modified triaxial apparatus. The
soil properties were the same as the above-mentioned values.
The SWCC of the soil was obtained by desaturating the soil
under a net confining pressure of 10 kPa. The volumetricwater
content versus soil suction SWCC is shown in Fig. 12.28.
The shear strength parameters for the saturated compacted
kaolin were φ =

Equations Soil Parameters

Oberg and Sallfors (1997) SWCC, S
Fredlund et al. (1996) κ = 0 . 446, θ s = 0 . 50, SWCC

Vanapalli et al. (1996b) θ s = 0 . 50, θ r = 0 . 120 , SWCC

Goh et al. (2010) n d = 3 . 271, ψ aev = 50 kPa,

PI, SWCC

31 . 1 ◦ and c =

with soil suction in a nonlinear manner. The equations by
Goh et al., (2010) and D.G. Fredlund et al., (1996) provide
relatively close estimations of the measured shear strengths.
The estimation procedures based on the SWCC appear to
reflect quite well the flattening of the strength envelope at
high suctions.

0 kPa. Soil parameters from
the SWCC required for the estimation of shear strength with
respect to soil suction are listed in Table 12.5.
The measured shear strength data on the compacted kaolin
along with estimations of the shear strength envelope are
shown in Fig. 12.29. The measured shear strength increases