Can degree of saturation decrease during constant suction compression of an unsaturated soil

Abstract

Abstract The fraction of water within the soil pore space (often represented by the degree of saturation) conveys critical information about the flow, deformation and strength characteristics of the unsaturated soils, and is affected by both hydraulic (matric suction) and mechanical (volumetric deformation) state of a soil. Accurate prediction of the variation of degree of saturation with soil volumetric deformation is therefore essential for the correct characterization of the behaviour of unsaturated soils. The majority of the experimental data show that the degree of saturation increases upon volumetric contraction at constant suction, however there are experimental data to the contrary. In this paper, the possibility of a decrease in the degree of saturation upon volumetric contraction is explored and the phenomenon is described using an effective stress based theoretical framework. Comparisons between predictions and experimental data are provided using the framework proposed.