2 / 2025-07-02 12:55:56

Influence of Erodible Substrate Topography and Material Strength on Landslide Mobility：Insight from MPM

Landslide mobility,Erodible substrate,Topography,Numerical simulation,MPM

Topography and strength of substrate are key factors controlling landslide mobility. However, the coupled influence of these substrate properties on landslide mobility ​​remains​​ unclear. This study employs the material point method (MPM) to investigate the impact of substrate topography and material strength on the runout of landslide. Two flume experiments, a granular column collapse test and a granular flow traveling on an erodible substrate, were used to validate the model first. Then, six groups of simulations with different substrate inclinations and substrate conditions were conducted (Fig.1). The simulation results reveal that increased substrate inclination and reduced material strength can significantly enhance landslide mobility. Compared to substrate-free conditions, a 13% reduction in maximum travel distance confirms mobility increase caused by the erodible substrate in these simulations. At constant substrate inclination, reduced material strength lowers the shear resistance of substrates, thereby enhancing mobility. Conversely, under invariant material strength conditions, increased substrate inclination reduces the effective erosion resistance, simultaneously diminishing normal erosion velocity and amplifying tangential shearing velocity. This mechanical response induces dilation of the basal shear zone and diverts kinetic energy from vertical dissipation into lateral momentum transfer, thereby amplifying downstream flow mobility. High substrate strength buffers topography-driven mobility enhancement, while strength reduction governs mobility increases independent of topographic configurations. This research demonstrates that integrated analysis of strength-topography coupling is essential for landslide hazard assessment.