A thermo-poro-mechanical model for catastrophic landslides under unsaturated conditions

Abstract

Large landslides are one of the most menacing geological hazards in mountainous regions around the world due to their high-speed, large-scale characteristics. Up to now, the thermo-poro-mechanical coupling mechanism of catastrophic landslides under initial water-saturated conditions has been recognized by many scholars. Nevertheless, most slip zones of landslides are located in both the unsaturated and saturated zones and the unsaturated zone can account for a much larger portion when the groundwater level is relatively low. Typical examples of this situation include many loess landslides which have occurred in northwestern China. In this study, a unified quasi two-dimensional thermo-poro-mechanical model was proposed taking into account both the unsaturated and saturated zones in the slip band of landslides and an attempt was made to describe the complete movement process. Moreover, the Dongfeng loess landslide was chosen as a case study with an assumed triggering condition, and the model was validated by comparison between the simulation results and previous published work. A sensitivity analysis demonstrated that the frictional heating mechanism and the presence of a dry air phase in the slip band have clear impacts on the characteristics of the landslide. In particular, it was found that the soil–water characteristic curve and the initial degree of saturation are of significance.