Volume Change Consideration in Determining Unsaturated Soil Properties for Geotechnical Applications

Abstract

A common underlying assumption in the development of soil-water characteristic curves (SWCCs) is that the soil is sufficiently stiff such that no changes occur in the volume of the soil associated with soil-suction change. A number of researchers recently recognized the importance of considering soil-volume changes in SWCCs; however, few researchers have evaluated the effect of volume change on the computed rate and degree of wetting/drying of unsaturated soils and the associated impact on computed soil-volume change response. This paper focuses on the impacts of considering soil-volume change in the determination of SWCCs for high-volume-change soils, with emphasis on the estimated unsaturated hydraulic conductivity function and response to wetting. Numerical simulations of unsaturated flow and suction-induced volume change were used to study the effect of consideration of volume change in the determination of SWCCs. Numerical analyses used laboratory-determined SWCCs with and without the inclusion of volume change measurements. The study results demonstrate that the impact of volume change consideration on SWCCs and the estimated unsaturated hydraulic conductivity function can be quite substantial for high-volume-change soils such as expansive clays.