Environmental Engineering Reference
In-Depth Information
120
Initial condition
100
80
60
40
20
0
10
6
0.1
1
10
100
1000
10,000
100,000
Soil suction, kPa
Figure 13.49
Degree-of-saturation changes for artificial silt.
10
6
10
6
0
0
10
4
10
4
0
0
Net mean stress (kPa)
(a)
Net mean stress (kPa)
(b)
10
6
10
6
0
0
10
4
10
4
0
0
Net mean stress (kPa)
Net mean stress (kPa)
(c)
(d)
Figure 13.50
Four series of stress paths for studying volume-mass constitutive surfaces of
unsaturated soil: (a) series 1: loading and then drying from initially slurry conditions; (b) series
2: drying and then loading from initially slurry conditions; (c) series 3: loading and then wetting
from initially dry conditions; (d) series 4: wetting and then loading from initially dry conditions.
behavior of soil specimens with the same initial and final
stress state but following two different stress paths that
involve wetting processes.
Figure 13.51 shows that the calculated volume-mass
constitutive surfaces agree well with postulated volume-
mass constitutive surfaces presented by M.D. Fredlund
et al., (2000b). The computed results show that (i) there
is a one-to-one relationship between changes in void ratio
and water content as net mean stress and soil suction are
changed when soil suction is less than the air-entry value;
(ii) there is a gradual change in curvature that develops on
the water content constitutive surface as the air-entry value
of the soil is exceeded; and (iii) there is a gradual change
in curvature that develops on the void ratio constitutive
surface as the air-entry value is exceeded.
Figures 13.52-13.54 show several volume-mass consti-
tutive surfaces predicted for the three artificial soils pre-
viously mentioned. The predicted constitutive relationships
near zero suction and zero net mean stress planes are reason-
able. The volume-mass constitutive surfaces starting from
Search WWH ::
Custom Search