Finite element modelling of unsaturated soils using a modified version of the Barcelona Basic Model

Abstract

In this paper, unsaturated soil behaviour is numerically simulated using a modified version of the Barcelona Basic Model. The model has been implemented as a User-Defined Soil Model (UDSM) in the finite element code PLAXIS. Unlike the original formulation based on net stress ([1]), this model isformulated based on the well-known Bishop’s effective stress, with suction as an additional stress variable. Furthermore, a non-associated flow rule and the dependency on Lode’s angle proposed by [2] are incorporated. The Soil Water Characteristic Curve (SWCC) follows the Van Genuchten model ([3]). First, the simulation of laboratory tests along different stress paths and levels of suction are compared againstexperimental data. Then, an unsaturated soil embankment subject to a time-dependent precipitation is simulated by means of a fully coupled flow-deformation analysis. The results show the capability of the model to reproduce the main features of unsaturated soil behaviour both at material point level and inboundary value problems.