Numerical modelling of the thermo-mechanical behaviour of soils in catastrophic landslides

A new landslide model is proposed by improving on an existing one, which is able to interpret using a simple I-D mechanism the post-failure sliding regime of catastrophic landslides and rockslides consisting of a coherent mass sliding on a thin clayey layer. The model takes into account frictional heating and subsequent pore pressure build-up, leading to the vanishing of shear resistance and unconstrained acceleration. First, an existing thermo-elasto-plastic constitutive model for clays is discussed, and modified by re-formulating it in a general stress space and taking into account thermal softening. The soil constitutive model is then employed into an existing landslide model. The resulting model equations are shown to be well-posed, and then are discretised and integrated numerically to back-analyse the final stage of the well-documented case history of Vajont that occurred in Italy in 1963. Finally, the results are used to highlight the possible importance of thermal softening in the development of catastrophic failure.