Effect of high-frequency microseismicity on shear strength of interlayer structural planes of bedding rock landslides

Water storage in the Three Gorges Reservoir in China has increased the regional microseismicity. Bedding-rock landslides, one of the most common slope structures in the Three Gorges Reservoir, are highly prone to sliding under seismic loading. Existing research primarily focuses on the stability of bedding rock landslides under strong earthquakes, while studies on the cumulative damage and long-term stability of bedding rock landslides under high-frequency microseismicity remain immature. In this study, we considered bedding rock landslides under high-frequency microseismicity in the Three Gorges Reservoir area as the research subject and equivalent microseismicity as pre-peak cyclic loading. First, we analyzed the shear strength deterioration of rock mass structural planes under pre-peak cyclic loading conditions and found that the deformation and failure of structural planes involve contact and damage effects. The shear strength of the rock mass structural planes under pre-peak cyclic loading conditions is affected by the confining pressure, loading rate, loading amplitude, and number of loading cycles. Among these factors, the shear strength of the structural planes was the most sensitive to the number of loading cycles. As the number of cycles increased, the rock mass structural planes underwent three stages: stress adjustment (increase in shear strength), fatigue damage (gradual decrease in shear strength), and structural failure (rapid decrease in shear strength). The stability of bedding rock landslides under high-frequency microseismicity was analyzed, revealing that the stability of bedding rock landslides under high-frequency microseismicity can be divided into three stages: short-term enhancement, gradual degradation, and rapid deterioration, exhibiting characteristics of gradual and sudden changes.