Numerical model for unsaturated sandy soils under cyclic loading: Application to liquefaction

This paper includes a presentation of a numerical model for the description of the behavior of unsaturated sandy soils under cyclic loading with particular attention for liquefaction. The model is developed within the framework of the theory of Biot and the formulation of Coussy. It is also based on laboratory observations. The formulation leads to a simplified model, which allows also to deal with saturated soils. The cyclic elastoplastic constitutive model “MODSOL” is used to describe the cyclic behavior of the soil. The paper presents an analysis of the influence of the soil saturation on the response of a sandy soil to both monotonic and cyclic undrained loading paths. It shows that the decrease in the saturation degree of a sandy soil leads to an important increase in their resistance to liquefaction.