Connecting landslide basal sliding surface characteristics with post-failure kinematics and impact on rigid structures: An MPM numerical study

Understanding the landslide failure mechanism, the deformation process, and ultimately the impact forces generated by landslides on structures is essential for risk assessment. This paper connects these three aspects using the Material Point Method (MPM) and highlights the effect of landslides’ basal failure surface characteristics (i.e., geometry and interface friction) on (a) failure mechanism, (b) post-failure kinematics, and (c) impact force on rigid structures. The geometry of a biplanar landslide is considered, along with different types of slope transitions along the sliding basal surface, from a rotational landslide to a perfect biplanar landslide. A comprehensive parametric study with 310 simulations is performed to analyze the landslide post-failure behavior in terms of the radii of transition, the basal friction angle, the distance to the rigid wall, the roughness of the rigid wall, and the scale of the landslide. The results are presented regarding energy evolution, maximum impact force on the rigid wall, and final runout (in the absence of the wall). Results show that relatively small changes in the slope transition can have relevant impacts on kinematics and impact force. For validation purposes, the maximum impact force resulting from numerical results is compared to the predictions from existing semi-empirical approaches, which compare reasonably well. Finally, different methods to evaluate the impact velocity are evaluated, and the effect of numerical practices in the study of impact forces is also discussed.