Modeling the Behavior of Expansive Soils Using Effective Stresses

Abstract

In the past 15 years, different researches have shown that the effective-stress approach represents a simple and precise way to generate fully coupled constitutive models for unsaturated soils. This is so because the influence of the degree of saturation and the hysteresis of the retention curve are implicit in the formulation. Here, an elastoplastic framework for the volumetric behavior of expansive soils based on effective stresses is proposed. The hydraulic behavior of the soil is simulated using a porous-solid model able to reproduce wetting–drying cycles. The porous-solid model is based on the current pore-size distribution (PSD) of the soil. Therefore, volumetric deformations can be related to variations in the PSD. The result is a fully coupled elastoplastic framework based on the equation of the volumetric behavior of saturated soils where the compression index depends on the position and direction of the state of stresses with respect to the yield surfaces. Experimental and numerical comparisons show the ability of the model to simulate the behavior of expansive soils under different stress paths.