Numerical modelling of a slope stability test by means of porous media mechanics

Purpose - The purpose of this paper is to present a finite-element analysis of the initiation of a slope failure in a small-scale laboratory test due to pore pressure variation. To this aim, a fully coupled multiphase model for saturated/partially saturated solid porous materials based on porous media mechanics is used. Design/methodology/approach - The slope is described as a three-phase deforming porous continuum where heat, water and gas flow are taken into account. The gas phase is modelled as an ideal gas composed of dry air and water vapour. Phase changes of water, heat transfer through conduction and convection and latent heat transfer are considered. The independent variables are: solid displacements, capillary pressure, gas pressure and temperature. The effective stress state is limited by Drucker-Prager yield surface for the sake of simplicity. Small strains and quasi-static loading conditions are assumed. Findings - The paper shows that the multiphase modelling is able to capture the main experimental observations such as the local failure zone at the onset of slope failure and the outflow appeared in that zone. It also allows understanding of the triggering mechanisms of the failure zone. Research limitations/implications - This work can be considered as a step towards a further development of a suitable numerical model for the simulation of non-isothermal geo-environmental engineering problems. Practical implications - The multiphysics approach looks promising for the analysis of the onset of landslides, provided that the constitutive models for the multiphase porous media in saturated/unsaturated conditions and the related mechanical and hydraulic properties are described with sufficient accuracy. Originality/value - Elasto-plastic thermo-hydro-mechanical modelling of the initiation of slope failure subjected to variation in pore pressure boundary condition.