Experimental study on the effects of different rainfall patterns on deformation and failure of bedding rock slopes with weak interlayers

ObjectiveThe Three Gorges Reservoir area, a region prone to heavy rainfall, is one of the most landslide-prone areas in China. Under the influence of rainfall, bedding rock slopes are particularly susceptible to landslides. Statistics indicate that 64% of the massive and large landslides occur in such structural rock slopes, especially bedding rock slopes with weak interlayers, posing severe threats to the safety of people and property. Therefore, understanding the deformation characteristics of these bedding rock slopes and their response to rainfall patterns is of great significance for the construction and operation of the reservoir area. MethodsThis study used the Shanshucao bedding rock slope as a prototype and conducted scaled physical model tests to simulate the entire deformation and failure process of bedding rock slopes with weak interlayers under four different rainfall patterns: Front-peak, middle-peak, rear-peak, and no-peak. The tests were designed to analyze the evolution characteristics of the stress field and seepage field within the slope and to identify the stages of slope deformation and failure. ResultsThe research findings indicated that: (1) Different rainfall patterns primarily affected the response time of stress and seepage in the weak interlayer, with minimal impact on the interaction forces within the rock mass. (2) The stress redistribution caused by bedding rock slopes with weak interlayer was mainly concentrated in the weak interlayer, with the stress variation being most significant at the toe of the slope. Although the trends of pore water pressure and displacement changes in the weak interlayer were generally similar under different rainfall patterns, there were significant differences in the initial response time of pore water pressure. (3) Under different rainfall patterns, the landslide failure modes were mainly characterized by overall sliding failure and local sliding-tensile cracking failure. As the rainfall peak position shifted forward, the traction-type failure became more pronounced, which manifested by a forward shift in the location of the rear edge cracks of the landslide. (4) Based on the macroscopic deformation characteristics of the slope observed in the physical model tests and multi-field monitoring data, the deformation and failure process of the bedding rock slope could be divided into three stages: Deformation at the leading edge, the strain accumulation and development stage, and the overall accelerated deformation stage.ConclusionThese findings reveal the response patterns of the deformation characteristics and evolutionary processes of bedding rock slopes to rainfall patterns, which provides important insights for landslide hazard prevention and the safe operation of resevoir areas.