The role of unsaturated soil property functions in the practice of unsaturated soil mechanics

Abstract

The implementation of unsaturated soil mechanics into engineering practice is dependent, to a large degree, upon an ability to predict nonlinear, unsaturated soil property functions. Such unsaturated soil property functions as the soil-water characteristic curve, the shrinkage curve, the permeability curve, and the shear strength curve have been shown to vary depending on water content levels. These unsaturated soil property functions have been defined for the classical soil mechanics areas of seepage and shear strength. Much information has been accumulated on the volume change behavior of unsaturated soils; however, to-date the role of unsaturated soil, volume change functions has not been defined; nor have the prediction procedures been formulated. The primary objective of this thesis is to provide methods of determining the constitutive relationships for an unsaturated soil. Experimental laboratory techniques, theoretical and statistical methods will be examined to provide the basis for the constitutive surfaces. Soil property functions will also be represented mathematically to facilitate a continuous and smooth representation of soil behavior. The resulting constitutive surfaces will provide the practicing engineer with mathematical relationships that form the basis for modeling seepage and volume change (or any coupled combination) in unsaturated or saturated soil.