[H-DS05] Landslides and related phenomena

[HDS05-P13] Meltwater-driven lubrication and pseudo-cohesion in rock-ice avalanches: new insights from discrete element and liquid bridge simulations

*YUHAO REN¹, Fei Cai¹, Qingqing Yang², Zhiman Su³ (1.Gunma University, 2.Southwest Jiaotong University, 3.Institute of Mountain Hazards and Environment, Chinese Academy of Sciences)

Keywords:rock-ice avalanche, liquid bridge force, DEM

Rock-ice avalanches have attracted wide attention in recent years because they pose an imminent threat to the vulnerable ecosystems and civilization in high-mountain and glacierized environments. The meltwater effects on the behaviors and mobility of rock-ice avalanches in pendular regime remains an issue. A scheme incorporating a set of liquid bridge force models into the discrete element method was proposed to simulate the mechanical behaviour of liquid bridges, regarding basal lubrication and pseudo-cohesion. The numerical results indicate that the basal lubrication arising from subtle meltwater increased the mobility of the mixtures. For the cases with ice content larger than 60%, the pseudo-cohesion counteracted the mobility enhancement and brought about an attenuated frontal splash and a segmental deposit; these three typical features were more evident with an increase in ice content. System energy was found to be dissipated mainly through friction, particularly basal friction, and the energy dissipated through liquid bridges might account for 30% approximately in high ice content cases. The morphology evolution and runout distance of gravel-ice mixtures were found to be heavily subject to the initial layering arrangement, suggesting the significance of the compound effect of separation and basal friction attenuation. This work demonstrated the crucial impact of the liquid bridges in gravel-ice mixtures and offered a promising scheme for deeply understanding the dynamics of the rock-ice avalanches in pendular regime.