Energy transfer mechanisms of mobility alteration in landslide-debris flows controlled by entrainment and runout-path terrain: A case study

The movement of landslide-debris flows is strongly affected by entrainment and runout-path terrain. Herein, mobility alteration was explored from an energy perspective via the discrete element method, using the Shaziba geohazard. The dynamics of the Shaziba geohazard were investigated based on field investigations and numerical simulations. The multiple energy evolutions, conversions, and dissipations of different initiation areas and distinct landslide processes, including kinetic, potential, frictional, and collisional energy, were quantitatively and systematically investigated. The simulation results provide a clear presentation of the inter-particle interactions and energy transfer behavior. Friction caused the most significant energy dissipation, yet collisions dominated the mobility reduction during the entrainment process and interactions with the runout-path terrain. The entrained area possessed higher mobility due to entrainment-induced energy transfer, with distinct forms of energy supplement at different depths. Moreover, the deflection and arching effects of runout-path terrains altered the velocity and direction of landslides and could be used to explain the dissipation of landslide energy as well as reduced mobility. At the cliff, the high-velocity and near-vertical impact on the sediment resulted in the rapid dissipation of landslide energy in collisions. The results provide a reference for analyzing and predicting the movement and mitigating threats of similar geohazards.