Modified Hierarchical Single-Surface Model for Unsaturated Soils

Abstract

A user-defined unsaturated modified hierarchical single-surface model is developed. The surface of this modified model is continuous and avoids the problems of multisurface models. The nonassociative flow rule, suction stress, and hardening parameters of suction were considered in this model to reflect the suction effects on the effective stress and the shape of the yield surface. Moreover, the model was implemented in a commercial finite-element program associated with a user subroutine written in FORTRAN. The ultimate outcomes after comparison with the experimental results revealed the appropriateness of the modified unsaturated hierarchical single-surface model.