Hydro-Mechanical Properties of an Unsaturated Frictional Material

180CHAPTER 8. NEW SWCC MODEL FOR SAND INCLUDING SCANNING CURVES
40 50
30 Values
Observed
10 20 30 40 50 Predicted Values 0 10 20
110
10
of observations
Number
stest column test I Loose specimen Initial void ratio = 0.89 2nd drainage Transient
rate = 100 ml/min TDR/T 160 mm Flow
-0,4 -0,2 0,0 0,2 0,4 0,6 Residual Values 0123456789
-0,6
0,4 0,6
0,2 Values
Residual
10 20 30 40 50 Predicted Values -0,6 -0,4 -0,2 0,0
0
1,0 1,5 2,0 2,5
0,5 Normal Value
Expected
0.85 0.95 0.99
0.70
-0,4 -0,2 0,0 0,2 0,4 0,6 Residuals -2,5 -2,0 -1,5 -1,0 -0,5 0,0
0.01 0.05 0.15 0.30 0.50
-0,6
Figure 8.7: Model validation results from 2 nd drainage process (loose specimen, TDR/T160
mm)
Appendix E) for dense specimen during drainage process that is attributed to the minor
set of data, where only few results are available in the unsaturated zone (θ < 34%) and
most data are available in the saturated zone (θ = 34%).
Plots of residual versus predicted variables and observed versus predicted variables are
given in Fig. 8.8 and 8.9 for imbibition process of loose specimen (and respectively in
Appendix E in Figs. E.8 and E.9 for dense specimen). The plots of the observed versus
predicted values from imbibition curve show slight variations between measured and
calculated values. Nevertheless the points are linear related. The scatterplots of the
residual versus predicted values are randomly distributed in Fig. 8.9. Non-randomness
is observed in Fig. 8.8. Similar to the results derived from drainage curve fit the points
are crowded in the saturated zone and in the residual zone, where most measurements
were achieved while withdrawing and injecting water.
- Normal probability plot:
The normal probability plots in Figs. 8.6 and 8.9 from both, drainage and imbibition
process, show that it is reasonable to assume that the random errors of the process are