Hydro-Mechanical Properties of an Unsaturated Frictional Material

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CHAPTER 7. ANALYSIS AND INTERPRETATION OF THE EXPERIMENTAL
RESULTS
tion of the observed values in the plot of observed versus predicted values and in the lower
coefficient of regression determination R 2 = 0.966.
All best fit results are given in Fig 7.3 for the loose specimens. Volumetric water con-
tent versus suction θ(ψ) and saturation versus suction S(ψ) are shown. The best fitted
curve derived from Brooks and Corey’s (1964) function shows differences between the fit and
experimental data in the region of the air-entry value (drainage process), in the residual
zone (drainage process and imbibition process) and in the saturated zone (drainage process).
However, the best fitted curve was derived by Fredlund and Xing’s (1994) equation. Good
agreement in the sensitive zones as air-entry value, residual zones, water-entry value was
found. Thus Fredlund and Xing’s (1994) equation is used for further best fit procedure and
also for further analysis of unsaturated hydraulic conductivity (indirect method, statistical
model). Best fit results derived from residual analysis from all the experimental data are
summarized in Appendix B in Figs. B.1 to B.10. The soil-water characteristic curves are
plotted as volumetric water content versus suction as well as saturation versus suction. For
further interpretation and analysis of the results the best fitted of soil-water characteristic
curves are used.