Impact of terrain variation on landslide mobility: Insights from DEM simulations

S Zhou and CQ Zhu and Y Huang and J Sun, COMPUTERS AND GEOTECHNICS, 179, 107050 (2025).

DOI: 10.1016/j.compgeo.2024.107050

Uneven basal terrain is an important component of high-speed and long- run-out-distance landslides. However, the mechanism by which terrain variability affects landslide mobility remains a challenging and unresolved problem. In this study, we conducted terrain analysis on five recent landslides to quantify their terrain variation. On the basis of these data, we explored the effect of terrain variation on the mobility of landslides through simulations of simplified granular chute flows using the discrete element method. Our results revealed that the basal terrain variation could increase the landslide velocity and the existence of a characteristic terrain that could increase landslide velocity most. Microstructure and stress-state analysis showed that the increase in landslide mobility is related to a decrease in solid-volume fraction and an increase in velocity fluctuation. Moreover, terrain variation caused the flow state to deviate from a steady simple shear condition, implying the inapplicability of the current mu(I) rheological model under such conditions. However, the landslide stress ratio retains a good correlation with velocity fluctuation and inertial number, indicating that the velocity fluctuation (granular temperature) is a key factor in the construction of rheological models under complex conditions. In general, the influence of terrain variation on landslide mobility is attributed to the combined effects of the compression, expansion, and gravitational waves in the granular system. These effects result in a loose granular system and a decrease in the solid-volume fraction, enhancing the mobility of a landslide. This study improves our understanding of the high-speed and long-run-out-distance mechanism of landslides.

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