Numerical Modeling of Hydraulic Hysteresis in Unsaturated Soils

Abstract

This article presents the implementation of the constitutive model of Wheeler (Geotechnique 53(1):41–54, 2003) for coupling of hydraulic hysteresis and mechanical behavior of unsaturated soils in a fully coupled transient hydro-mechanical finite element (FE) model (computer code UNSATEX) developed by the authors. The constitutive model considers the effects of irreversible changes of degree of saturation on stress–strain behavior and the influence of plastic volumetric strains on the water retention behavior. The mathematical framework and the numerical implementation of the constitutive model are presented and discussed. The FE model is verified and validated against analytical predictions [obtained using the model of Wheeler (Geotechnique 53(1):41–54, 2003] as well as experimental results from the literature involving unsaturated soils undergoing various combinations of drying, wetting, loading, unloading, and reloading paths. Comparison of the results shows that the developed FE model can be used to predict various aspects of the behavior of unsaturated soils under drying and wetting as well as loading and unloading paths. The merits and limitations of the FE model are highlighted.