Finite element analysis of the initiation of landslides with a multiphase model

Finite element analysis of non-isothermal elasto-plastic multiphase geomaterials is presented. The multiphase material is modelled as a deforming porous continuum where heat, water and gas flow are taken into account. In particular, the gas phase is modelled as an ideal gas composed of dry air and water vapour, which are considered as two miscible species. Phase changes of water (evaporation-condensation, adsorption-desorption) and heat transfer through conduction and convection, as well as latent heat transfer are considered. The macroscopic balance equations are discretised in space and time within the finite element method. The independent variables are the solid displacements, the capillary and the gas pressure and the temperature. The effective stress state is limited by classical elastoplastic models. Small strains and quasi-static loading conditions are assumed. Numerical results of the initiation of landslides due to water pressure load are presented. It is shown that the first failure of the lower part of the slope is captured, as experimentally observed.