On frictional heating and pore pressure generation:Implications for coseismic landslides hypermobility

Abstract

Pore pressure plays a critical role in the hypermobility mechanism of landslides. In coseismic landslides, earthquake can further influence the variation of pore pressure. Among these factors, the dominant factor to explain the hypermobility mechanism of such coseismic landslides remains unknown. In this paper, considering the seismic loading and thermo-hydro mechanism, a novel FEM-FDM model is proposed to simulate the temperature increase and excessive pore pressure buildup from the initiation of the earthquake to the end of the landslide. The entire runout process of the landslide was simulated by the DAN model. Through the nonlinear finite element method, seismic records from the nearby seismic stations were analyzed to calculate the seismic excess pore pressure. The rising temperature and excess pore pressure in the shear zone were simulated through the seismic-thermo-hydro model. Based on the seismic-thermal-hydro model, the simulated results of the landslide indicated a rapid excess pore pressure increase within the shear zone. While seismic load may weaken the slope materials and induce the landslide, thermal pressurization mechanism can generate much larger excess pore pressure than seismic load does, leading to much lower effective normal stress and shear force resistance in the shear zone during the landslide motion.