Plane-Strain Modelling for Unsaturated Soil
The general analytical formulation for the plane-strain deformation regime of an elasto-plastic unsaturated soil is presented and then applied to two types of stress path: wetting at constant in-plane net stress state and in-plane loading at constant suction. Two different implementations of the plane-strain deformation regime are compared. The first one is correct whereas the second one assumes improperly that each single component of the total out-of-plane strain has to be null. This incorrect formulation is believed to be implemented in some finite element codes due to historical reasons. Modelling the soil behaviour by the constitutive model proposed by Alonso et al. (1990), substantially different load-displacement relationships are obtained with the two different formulations for the wetting paths. In the case of loading at constant suction the results from the two different formulations coincide in the elastic field and small discrepancies are observed when plastic deformations occur.
KeywordsUnsaturated Soil Stress Path Finite Element Code Intermediate Principal Stress Constant Suction
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