Consolidation of unsaturated soils: Identification of Biot's coefficient

This paper presents a description of a theoretical and experimental study of the thermohydromechanical behaviour of unsaturated soils under oedometric conditions. The theoretical study leads to two equations of volume changes of the solid skeleton and of the water of a soil element. The experimental study concerns laboratory mechanical consolidation tests on a silty clayey sand. The tests were performed at different temperatures and enabled the identification of Blot's coefficient b(e) of an unsaturated soil. The coefficient did not seem to depend on the state of stresses, but was strongly temperature-dependent. The approach used also made it possible to establish a link between an empirical equation that is becoming classic in the mechanics of unsaturated soils and theoretical equations based on the mechanics of porous media.