The progressive deterioration of rock slopes in cold regions, driven by seasonal freeze–thaw (F-T) cycles and repeated mining-induced disturbances, poses a significant threat to the long-term stability of engineering infrastructure. To elucidate the underlying damage mechanisms governing this process, this study conducted constant-amplitude multi-stage cyclic loading (CMSCL) tests on specimens preconditioned by 0, 40, 80, 120F-T cycles. Nuclear magnetic resonance (NMR), acoustic emission (AE), and Gaussian mixture model (GMM)-based crack classification correlated macro-mechanical response with micro-crack evolution. F-T cycling comminutes macropores and mesopores into micropores via volumetric expansion, hydrostatic pressure, and ice-water segregation, increasing total porosity, reducing P -wave velocity, and lowering fatigue strength by 38.81%. AE results indicate that F-T damage shortens the effective Kaiser effect stress interval, and the Felicity ratio ( FR ) declines continuously beyond crack closure. GMM analysis further reveals that F-T-induced micropores promote a shift from transgranular to intergranular fracture, increasing tensile cracks from 64.72% (F-T=0) to 76.02% (F-T=120). This study newly establishes that the Kaiser effect corresponds to stable tensile crack propagation, while its transition to the Felicity effect relates to frictional slip along shear cracks. The findings provide a mechanistic basis and quantifiable precursors for improving stability assessments and developing proactive warning systems in seasonally frozen rock engineering, thereby offering a foundation for understanding the synergistic effects of frost weathering and cyclic loading.
Zhang et al. (2026) studied this question.