A multiphase flow model for simulating fluidization and basal liquefaction of landslide

Abstract Background Landslide material evolves from solid to fluid-like, boosting mobility and travel distance through fluidization and basal liquefaction. Yet models that use only solid and fluid phases, one or two phases, can oversimplify the true complexity of landslide flow dynamics. Methods This study presents landslide dynamics simulations using a multiphase mass-flow model that accounts for three distinct phases: solid, fine-solid, and fluid. We accounted for the effects of fluidization and basal liquefaction by dynamically varying the internal and basal friction angles to improve the accuracy of multiphase landslide modeling. The model was validated using field and laboratory data. Result The simulation results clearly demonstrate that dynamic variations in both internal and basal friction angles play a crucial role in determining the runout distance, velocity, and depth of the material. Fluidization alone causes a broader lateral spread, whereas basal liquefaction markedly increases the runout distance, flow velocity, and depth variability within the flow. When a model incorporates both mechanisms, it produces the greatest runout distance and the widest lateral spread. Conclusion This model provides important insights into the contributions of fluidization and basal liquefaction to understanding landslide flow dynamics and offers a validated modeling approach. In addition, it improves the accuracy of landslide hazard simulations.