A quasi two-dimensional friction-thermo-hydro-mechanical model for high-speed landslides

For deep-seated landslides, thermal pressurization in shear zone has been considered an important cause of high-speed collapse. To quantify this mechanism, this study proposed a quasi two-dimensional friction-thermo-hydro-mechanical (FTHM) model, concerning the mechanisms of material frictional softening and thermo-hydro-mechanical softening during the start-up phase of high-speed landslides. In this model, the intact slide mass was divided into a lot of small slide blocks. The dynamic equations of each block, and the heat equations, pore pressure equations of each shear band were established respectively. The model fully considered the morphological characteristics of landslides, and variables such as velocity, temperature, excess pore pressure varied along both the normal and the tangential direction of the whole shear band during the slide mass movement. The model was applied to back-analyze the Vaiont landslide and the results were compared with existing one-dimensional models. It can be concluded that the irregular spatial shape of slide mass makes a difference on mechanism of thermo-hydro-mechanical softening which promotes the collapse, and that the quasi two-dimensional model is valid.