Controlling parameter for unsaturated soil property functions: validated on the unsaturated shear strength

Prediction equations for unsaturated soil property functions have become more attractive because laboratory tests of unsaturated soils are time consuming and expensive. To ensure that predicted soil property functions represent soil behaviour reasonably well, appropriate selection of the parameter that controls the performance of these prediction equations becomes imperative. Deduced from the typical desaturation characteristics of a soil, the effective degree of saturation has emerged to be the controlling parameter for unsaturated soil property functions. In this paper, soil suction is considered to become ineffective in affecting unsaturated soil property functions at and beyond the residual state. Comparisons between experimental shear strength data and predicted values obtained using the concept proposed in this study show a good agreement.