Hydro-Mechanical Properties of an Unsaturated Frictional Material

5.4. EXPERIMENTAL PROGRAM 113
Matric suction (kPa)
60
50
40
30
20
10
0
0 50 100 150 200 250
σ∗ (kPa)
ψ = 50 kPa
ψ = 20 kPa
ψ = 3 kPa
ψ = 1.5 kPa
Figure 5.12: Loading history of one dimensional compression and rebound tests
Unsaturated Hostun sand specimen with a suction value ψ = 5 kPa were wetted to study
the collapse potential. All specimen were prepared for loose conditions. During loading the
specimens with constant suction or water content were saturated from the bottom of the cell
by the attached burette at certain vertical net stress. The saturated specimen was loaded up
to 100 kPa and unloaded in fixed steps. Saturation process was carried out at vertical net
stresses of 5 kPa, 12 kPa and 25 kPa. The loading steps for loading and unloading path are
summarized in Tab. 5.9.
Table 5.8: Experimental programm for one dimensional compression and rebound tests
ψ = const Net stress σ
ψ = 1.5 kPa 0 12 25 50 100 125 150 200
ψ = 3.0 kPa 0 12 25 50 100 125 150 200
ψ = 20.0 kPa 0 12 25 50 100 125 150 200
ψ = 50.0 kPa 0 12 25 50 100 125 150 200
ψ = const Net stress σ
ψ = 1.5 kPa 200 150 125 100 50 25 12 2
ψ = 3.0 kPa 200 150 125 100 50 25 12 2
ψ = 20.0 kPa 200 150 125 100 50 25 12 2
ψ = 50.0 kPa 200 150 125 100 50 25 12 2