Use of Effective Stresses to Model the Collapse upon Wetting in Unsaturated Soils

Abstract

This paper presents the modeling of the phenomenon of collapse upon wetting using the effective stress approach. To this purpose, Bishop’s effective stress equation is applied in addition to an elastoplastic framework for the volumetric behavior of unsaturated soils. Bishop’s parameter χ is obtained from a porous-solid model that is able to simulate the soil-water retention curves during wetting-drying cycles. The proposed framework includes the hysteresis of the retention curve and to some extent the hydro-mechanical coupling of unsaturated soils. This model is able to reproduce quite precisely the phenomenon of collapse upon wetting using a single valued compressibility index. It also represents a unifying framework for saturated and unsaturated soils.