The Concept of Effective Stress in Unsaturated Soils - Multiscale Geomechanics: From Soil to Engineering Projects - page 168

(0.5)
()

E = E

[ 6 . 22]

( . ) () =

f e

0

0

2

(2.17 − e )

0

with

fe () =

and f (0.5) 1.859 =

0

1 + e

0

6.4. Experimental results

6.4.1. Isotropic compression paths

When the specimen is submitted to an isotropic compression stress, its capillary
pressure p c tends to decrease, but the change depends to a large extent on the water
content of the specimen (see Figure 6.13):

- when the soil is on the dry side of the optimum water content, the change is
negligible;

- on the other hand, wetter specimens exhibit a suction decrease with the rise of
stress, and significantly more so if their water content is high.

1000

1: w=3.74%

500

2: w=6.25%

3

4

5: w=9.5%

6

7: w=10.4%

8

100

9

10

11: w=18.3%

saturated

50

0 4 0 8 0

I s otropic stress p (kPa)

Figure 6.13. Influence of isotropic stress and water content on capillary pressure
[1: w=3.74%; 2: w=6.25%; 3: w=7.5%; 4: w=8%; 5: w=9.5%; 6: w=10%;
7: w=10.4%; 8: w=14.1%; 9: w=16.1%; 10: w= 17.9%; 11: w=18.3%]