Time-dependent damage mechanism of rock deterioration under freeze–thaw cycles linked to alpine hazards

The unique natural environment of the alpine terrains along the Tianshan highway has led to the frequent occurrence of hazards. The typical hazards in this area, such as sliding collapse, have obvious time-dependent deformation characteristics, and the extreme climatic change causes rock mass deterioration under freeze–thaw cycles, which serves as an important factor that indirectly triggers hazards, while the relationship between the time-dependent characteristics of hazards and the damage characteristics of rock mass deterioration triggering hazards remains uncertain. A series of microscopic examination and macroscopic mechanical experiments were conducted on quartz sandstone from the Tianshan highway to study the mechanism. The experimental results show that the cyclic freeze–thaw action changed the microstructure of quartz sandstone and weakened its mechanical performance. The weakening effect on the long-term mechanical characteristics is much more remarkable than that on the short-term characteristics, and the failure modes become more complicated after long-term loading. Based on the experimental phenomenon, the mechanism was analyzed, and a new constitutive model was established to reflect the long-term mechanical characteristics of rock with freeze–thaw cycles and predict the deformation of an unstable rock mass during collapse. These results can provide a reference for alpine hazard prevention.