Constitutive modeling for unsaturated soils considering gas hardening effect

Abstract

The influence of gases on unsaturated soils is discussed in the paper. First, the selection of stress state variables is discussed. It is shown that gas pressure as well as generalized effective stress and modified suction are required to construct a constitutive model of an unsaturated soil. The deformation mechanisms of solid, liquid and gas phases in soils are then investigated. It is realized that the deformation of gas phase interacts with the deformations of the other two phases in soils. Gas laws are used to describe the gas behavior. Similar to the other two phases in soil, the change of gas volume can be divided into an elastic part and a plastic part, and the latter part is then introduced to the soil hardening equation to reflect the impact of the gas on the soil. Then, a simple elasto-plastic model considering the gas effect for isotropic states is developed. Finally, the model predictions are given and compared with existing experimental data. A good agreement between them is found. Comparisons of the predictions between our model and Wheeler's model are also performed. © 2011 The Author(s).