Hydro-Mechanical Properties of an Unsaturated Frictional Material

9.5. SUMMARY 193
Pressure (Pa)
Pressure (Pa)
4000
3000
2000
1000
0
-1000
-2000
-3000
-4000
2000
1000
0
-1000
-2000
-3000
-4000
Results simulation Results experiment Depth 70 mm
Pressure (Pa)
Pressure (Pa)
4000
3000
2000
1000
0
-1000
-2000
-3000
-4000
2000
1000
0
-1000
-2000
-3000
-4000
Results simulation Results experiment Depth 160 mm
0 200 400 600 800 1000 1200 1400 1600 0 200 400 600 800 1000 1200 1400 1600
4000
4000
Results simulation
Results simulation Results experiment Depth 360 mm
Time Results
3000
(s) experiment Depth 260 mm
3000
Time (s)
0 200 400 600 800 1000 1200 1400 1600
Time (s)
0 200 400 600 800 1000 1200 1400 1600
Time (s)
Figure 9.7: Comparison of saturation versus time measurements and simulation including
hysteresis model from Parker and Lenhard (1987) - steady state test
9.5 Summary
Concluding, this work shows how modeling and experimental work can optimally be combined
in order to gain reliable predictions of hysteretic unsaturated flow. From the modeling point
of view, it is demonstrated that the implementation of a simple scaling approach for hysteresis
can provide a good prediction of hysteretic unsaturated flow including phase trapping effects.
However, this needs to be combined with reliable information of the input suction-water
content parameters that is commonly measured in the laboratory. It is shown that this is
possible by using direct saturation and pressure measurements on the column. If such data
were not available, the traditional approach that determines the soil-water characteristic curve
with separate steady state outflow/inflow would provide false information on the amount of
air trapping and, consequently, a misleading prediction by means of numerical simulations.