Interrelationship between Elastic Deformation and Soil-Water Characteristic Curve of Expansive Soils

Abstract

Compacted and undisturbed expansive soils have widely been modeled as dual-porosity materials with two levels of pore systems: micropores and macropores. The micropores accommodate the soil activity of swelling and shrinkage behavior. However, the macropores experience a volume change mainly resulting from the structural rearrangement. Due to the deformation of the macropores, a plastic volumetric strain takes place. However, after several wetting–drying cycles, an equilibrium state is reached. Beyond the equilibrium, the volume change becomes elastic and mainly is led by the micropores. This study investigated the volume change characteristics of expansive soils from the viewpoint of the soil shrinkage curve. The slope of the normal shrinkage curve at equilibrium was found to be parallel to the saturation line. Based on these observations and laboratory test results, a conceptual framework for the interrelationship between the virgin line of the soil-water characteristic curve and the reversible volume change of the micropores is presented. Experimental data demonstrated the applicability of the presented framework to slurry and compacted soils.