Influence of path materials on rock avalanche dynamics in the Nayong case study

Rock avalanches are highly destructive geological hazards marked by sudden onset, rapid acceleration, and substantial material entrainment. These characteristics render the investigation of their kinematic processes particularly challenging and complex. Using the Nayong landslide as a case study, we combine scaled laboratory experiments with numerical simulations to examine how path materials affect rock avalanche dynamics. Our laboratory tests reveal three key findings with fine river sand path materials. First, higher moisture content and wider path materials significantly enhance avalanche mobility. Second, downward displacement of path materials decreases mobility. Third, mobility shows a nonlinear relationship with accumulation depth - initially rising then declining as depth increases. Numerical simulations conducted using PFC3D successfully reconstructed the dynamic process of the Nayong landslide, revealing that reduced frictional resistance in path materials correlates with increased average velocities of both the collapsing source mass and entrained path materials. This research provides enhanced understanding of path material effects on rock avalanche dynamics and offers valuable scientific insights for disaster prevention and mitigation strategies.