西藏茶曲高位冰岩崩软弱带弱化特征与灾害链风险研究OA

[Objective]Under the influence of global warming and a humidifying climate,the frequency of the rock-ice avalanche disaster is steadily increasing.Among these,the occurrence of ice-rock avalanches is primarily controlled by ice-rock mixtures at the contact zones between glaciers and bedrock.However,the weakening characteristics of ice-rock mixtures and the formation processes of the ice-rock avalanche-debris flow disaster chain remain unclear.[Methods]This study focuses on the Chaqu Basin of the Qinghai-Xizang Plateau.Temperature-controlled triaxial experiments were conducted to investigate the failure characteristics of ice-rock mixtures under conditions of-8～0℃,ice-rock ratios of 0.25～0.75,and confining pressures of 200～400 kPa.Additionally,the motion patterns of the Chaqu BC01 high-altitude ice-rock avalanche hazard under-4℃ conditions were analyzed using Massflow simulations.[Results]The results indicate that the peak shear strength,internal friction angle,and cohesion of ice-rock mixtures decrease with increasing temperature.As temperature rises,the strength variation of ice-rock mixtures transitions from strain softening and shear failure to strain hardening and dilatancy failure.With an increasing ice-rock ratio,the stress-strain characteristics of the mixtures shift from strain softening to strain hardening.Using the Mohr-Coulomb strength criterion and Boltzmann function,the relationships among strength,ice-rock ratio,and temperature were characterized,and a strength failure criterion incorporating temperature and ice-rock ratio parameters was established.[Conclusions]Under extreme weather conditions,the Chaqu ice-rock avalanche is prone to forming an ice-rock avalanche-debris flow-river blockage disaster chain,which could obstruct the Palongzangbu River,posing significant threats to residents and infrastructure in the Palongzangbu River Basin.