Numerical Investigation of Landslide Runout on Freeze-Thaw-Affected Slopes Using a Smoothed Particle Hydrodynamics Method

Abstract Freeze-thaw cycling is a critical trigger of landslides with exceptionally high mobility, posing severe threats to residents in cold regions. However, previous studies have mainly focused on freeze-thaw-induced failure initiation, leaving postfailure dynamics and the factors controlling landslide mobility largely unexplored. Here, a novel numerical framework integrating erosion-deposition smoothed particle hydrodynamics (ED-SPH) with a strength reduction method (SRM) is proposed to simulate the failure process of freeze-thaw landslides, resolving the effects of freeze depth and slope angle. The equivalent coefficient of friction is adopted to quantify the mobility of freeze-thaw-induced landslides. The results show that the model successfully captures the transition from freeze-thaw-weakened soil failure to granular flow. Increased freeze depth amplifies landslide volume and reduces the equivalent coefficient of friction, whereas slope angle exerts limited influence on mobility. Furthermore, a power-law relationship is proposed between the equivalent coefficient of friction and relative landslide volume and is validated against field data from freeze-thaw slopes in the Loess Plateau in China. This inverse relationship enables rapid runout estimation, offering a practical tool for infrastructure risk assessment in cold regions affected by freeze-thaw processes.