Hydro-Mechanical Properties of an Unsaturated Frictional Material

5.4. EXPERIMENTAL PROGRAM 111
Volume of water in the specimen (ml)
20000
15000
10000
5000
Drainage
process
Loose specimen
Dense specimen
Imbibition
process
0 5 10 15 20
Loading steps
Figure 5.10: Loading history of steady state experiment in column testing device I for loose
and dense specimen
Transient state test was performed to study the influence of water flow condition on the
soil-water characteristic curve. Therefor water was withdrawn or injected to the sand sample
with a flow rate of 30ml/min and with a flow rate of 100ml/min through the reservoir at the
bottom (Tab. 5.7, Fig. 5.11). Water was pumped out of the specimen until the water level
reached the bottom of the specimen (drainage process) and then water was pumped into the
specimen until the water level reached the top of the specimen (imbibition process). The
applied flow rate caused a continuous change in suctions throughout the specimen.
Table 5.7: Experimental programm for transient state sand column tests
Loading path Flow rate [ml/min]
Initial drainage process 30
1 st Imbibition process 30
1 st Drainage process 30
2 nd Imbibition process 100
2 nd Drainage process 100