Shear Strength and Shear-Induced Volume Change Behavior of Unsaturated Soils from a Triaxial Test Program

A series of unsaturated soil triaxial tests were performed on four soils including sand, silt, and a low plasticity clay. Attempts were made to correlate unsaturated soil properties from these tests and data from the literature with soil-water characteristics curve (SWCC), soil gradation, and saturated soil properties. The feasibility of estimating unsaturated soil property functions from saturated soil properties, SWCCs and gradation data, is demonstrated. A hyperbolic model for estimation of the unsaturated soil parameter, phi(b), versus matric suction is presented. Shear induced volume change behavior was also studied, and results are included in this paper. Although not correlated with soil index properties, these shear-induced volume change data are important to complete stress-deformation analyses, and represent a significant addition to the existing data base of unsaturated soil properties.