Landslide dynamics with energy loss in internal shearing

Abstract As a crucial physical parameter, inter-particle friction plays a dominant role in the deformation, motion, and spreading of granular landslides. However, existing functional landslide models ignore the frictional energy loss in the internal shearing of granular material. Here, we propose a novel dynamical model that includes the frictional energy loss in internal shearing during the mass transport, making it a more complete landslide dynamical equation, for the first time, capable of describing the frictional energy dissipation. It includes a dimensionless intrinsic quantity describing the strength of frictional energy loss in internal shearing, internal friction angle, and dynamical quantities: the force induced by free-surface gradient, local extensional-compressional mode, slip velocity along the granular surface, and material weight. We access the model performance by presenting contrasting scenarios. Simulation results, including the 1903 Frank Slide, demonstrate the importance of frictional energy loss in actively controlling the deformation, motion, and deposition of sheared granular flows. Profiles and geometries are fundamentally different without and with considering frictional energy loss in granular shearing. Deposition structures appear more realistic for simulations with frictional energy loss, in line with observation, revealing the importance of frictional energy loss in internal shearing. This demonstrates, classical models, based solely on the basal Coulomb friction, cannot properly control the landslide dynamics. In contrast, the new model more accurately simulates the landslide propagation, run-out, spreading, and its fan morphology. This suggests the need to complement existing mass flow models with the new frictional energy loss principle in granular shearing in physically legitimately controlling the mass spreading, motion, and deposition.