Hydro-Mechanical Properties of an Unsaturated Frictional Material

9.4. COMPARISON OF SIMULATION RESULTS AND EXPERIMENTAL RESULTS 189
Saturation (-)
Saturation (-)
1.0
0.8
0.6
0.4
0.2
0.0
Saturation (-)
1.0
0 200 400 600 800 1000 1200 1400 1600
1.0
Time (min)
0.8
0.8
0.6
0.4
0.2
0.0
Results simulation
Results experiment Depth 70 mm
Saturation (-)
Results simulation
Results experiment Depth 260 mm
0 200 400 600 800 1000 1200 1400 1600
Time (min)
1.0
0.8
0.6
0.4
0.2
0.0
0.6
0.4
0.2
0.0
Results simulation
Results experiment Depth 160 mm
0 200 400 600 800 1000 1200 1400 1600
Time (min)
Results simulation
Results experiment Depth 360 mm
0 200 400 600 800 1000 1200 1400 1600
Time (min)
Figure 9.3: Comparison of pore-water pressure measurements and simulation including hysteresis
model from Parker and Lenhard (1987) - transient state test
time as well as pressure versus time measurements at several depths in the column.
The simulation results including the hysteresis concept from Parker and Lenhard that
considers also entrapped air compared to the experimental results are given in Fig. 9.3
and 9.4. The comparison between the predicted and measured saturation and pressure
is illustrated for four measurement depths. The results for the measurement point near
the bottom of the column are not presented as saturated conditions are maintained there
in both the experiment and the numerical simulation. As the comparison of the results
shows, the numerical simulation provides a good prediction of the experiment both in
terms of saturation and pressure. For the entire sequence of drainage and imbibition
events, the numerical simulation predicts the starting values of saturation and pressure
for each event (that strongly relate to the amount of trapped air) as well as to variation
of pressure and saturation in time. This can also be illustrated by plotting the resulting
soil-water characteristic curves from the experiment and the simulation (see Fig 9.5).
The simulation uses a rather simple scaling hysteresis concept and therefore achieved a
good prediction of the entire flow behavior in the transient state test.