Rock avalanches frequently exhibit accelerated movement, increased volume, and heightened hazards due to erosion at their base. However, our understanding of how topography modulates erosion mechanisms and sliding-promoting effects in rock avalanches remains limited. Drawing on physical tests and discrete element numerical simulations, this study systematically investigates the impacts of topographic conditions on erosion mechanisms and sliding promotion. The results demonstrate that the topography of the erosion zone exerts a pronounced influence on the spatial distribution patterns of deposits, which are characterized by compression, tension, and arcuate uplift. Meanwhile, impact erosion caused by sliding masses significantly reshapes topographic relief. Deflected terrain can trigger fluid-like behavior in sliding masses, featured by a brief intensification of movement followed by rapid attenuation, thereby enhancing both the acceleration and dispersal of the sliding material. Erosion mechanisms vary substantially depending on the contact angle between the sliding mass and the underlying topography, with erosion-related physical parameters highlighting the dominant role of terrain features. Notably, the interaction between sliding masses and side boundaries generates substantial lateral pressure, which intensifies basal scraping and further facilitates movement—this effect is particularly pronounced on slopes with gradients ranging from 15° to 30°. Sliding masses display greater mobility in gully terrain than on smooth slopes, whereas excessive terrain curvature may inhibit the erosion process. Collectively, these findings deepen our mechanistic understanding of how topography governs erosion and sliding effects in rock avalanches, providing a robust theoretical basis for the formulation of targeted disaster prevention and mitigation strategies.
 

Rock avalanche, Erosion mechanism, Sliding effect, Topography, Physical test,Numerical simulation