Fracture Propagation Characteristics and Catastrophic Modes of Fractured Rock in Alpine Region under Climate Change

Chen Guoqing; Xu Qiang; Yang Xin; Sun Xiang

doi:10.3799/dqkx.2024.030

Abstract：Under the influence of climate change,frost-weathered rock masses in high-altitude regions are prone to deterioration due to long-term freeze-thaw cycles.This deterioration can lead to sudden slope instability.To analyze the fracture mechanisms and corresponding hazard patterns under freeze-thaw cycles,it conducted field investigations on failure modes in high-altitude regions and freeze-thaw tests on fractured granite and quartz sandstone with varying crack lengths.By utilizing acoustic emission(AE)systems and strain testing systems,it analyzed the entire process of crack propagation at the end of the fissures,observing AE and microstrain curve variations.Based on experimental and theoretical discussions,it identified three main hazard patterns for fractured rock masses under freeze-thaw conditions:frost heaving,thaw subsidence,and freeze-thaw cycling.For the widely observed frost heaving pattern,the rock sample tests revealed that crack propagation occurred vertically downward from the crack ends,without deviation or secondary phenomena.While granite samples exhibited more pronounced initial crack propagation,quartz sandstone fissures tended to connect earlier.The AE count for granite showed an initial increase followed by a decrease,while quartz sandstone exhibited a steady count initially,which rapidly increased with more freeze-thaw cycles.Fracture mechanics analysis indicates that the expansion characteristics of fissured rock masses under freeze-thaw conditions are primarily influenced by rock type and crack length.Consequently,the formation of hazards in high-altitude regions is controlled by rock type and crack propagation.The research provides a theoretical basis for understanding the evolution of fractured rock masses and their hazard patterns in cold regions.