Abstract
Taking the "Banbiyan" dangerous rock in the Three Gorges Reservoir area as the research background, the damage evolution characteristics of this type of shear zone-bedrock interface under wet-dry cycles were investigated through wet-dry cycle tests, shear tests, and numerical simulation methods. The research results are as follows: the peak shear strength of the shear zone-bedrock interface is positively correlated with normal stress and negatively correlated with the number of wet-dry cycles; with the increase of wet-dry cycles, the total degradation degree of interface cohesion gradually increases and tends to stabilize, while the average degradation degree at each stage gradually decreases; the total degradation degree of internal friction angle increases, but the average degradation degree at each stage shows little difference; based on the mineral composition characteristics of the Jialingjiang Formation limestone, a mesoscopic parameter degradation model for the interface under wet-dry cycles was established and its reliability was verified; using this model for numerical simulation expansion, the variation laws of peak shear strength, crack number evolution, and total internal energy change of specimens for interfaces with different height-to-length ratios under wet-dry cycles were obtained; an empirical formula for interface shear strength parameters considering different height-to-length ratios under wet-dry cycles was proposed, and the obtained formula indicates that the height-to-length ratio of the interface has a more significant effect on the degradation of interface strength than the number of wet-dry cycles. The research results provide reference value for studies on the overall mechanical properties of shear zones under reservoir water action and the stability of dangerous rocks containing shear zones.
Full Text
Damage Evolution Characteristics of Shear Zone-Bedrock Interface Under Wet-Dry Cycles
Guo Xueyan¹,², Liu Xinrong¹,²,³
¹School of Civil Engineering, Chongqing University, Chongqing 400045, China
²National and Local Joint Engineering Research Center for Environmental Geological Disaster Prevention and Control in Wushan Section, Chongqing University, Chongqing 400045, China
³Key Laboratory of New Technology for Construction of Cities in Mountain Area, Ministry of Education, Chongqing University, Chongqing 400045, China
Abstract
This study investigates the damage evolution characteristics of shear zone-bedrock interfaces under wet-dry cycling. The peak shear strength of the interface exhibits a positive correlation with normal stress and a negative correlation with the number of wet-dry cycles. As wet-dry cycling progresses, the total degradation degree of interface cohesion gradually increases and stabilizes, while the average degradation per stage progressively decreases. The total degradation of the internal friction angle also increases, though the average degradation at each stage remains relatively constant. Based on mineral composition characteristics of Jialingjiang Formation limestone, a mesoscopic parameter degradation model was developed for the interface under wet-dry cycling conditions and its reliability was verified. Extended numerical simulations using this model revealed the evolution patterns of peak shear strength, crack propagation, and total internal energy for interfaces with varying height-to-length ratios under wet-dry cycling. An empirical formula for interface shear strength parameters that accounts for different height-to-length ratios was proposed. The formula demonstrates that the interface's height-to-length ratio exerts a more significant influence on strength degradation than the number of wet-dry cycles. These findings provide valuable insights for investigating the overall mechanical behavior of shear zones and the stability of hazardous rock masses containing shear zones under reservoir water action.
Keywords: Three Gorges Reservoir area; water-rock interaction; shear zone-bedrock interface; wet-dry cycles; degradation patterns