Study of the slope deformation characteristics and landslide mechanisms under alternating excavation and rainfall disturbance

To investigate slope stability under alternating excavation and rainfall disturbance and to reveal the intrinsic mechanism of the slope stress diffusion process caused by stress-seepage coupling, a method consisting of separate simulation of the excavation stress field and rainfall seepage field and superposition analysis is proposed. Meanwhile, the distribution of the pore water pressure and transient saturation zone in the AK2 + 210 ~ AK2 + 610 section slope of a highway in Guangdong Province, China, is comprehensively analysed by calculating the rainfall seepage field during the excavation process. The effects of the rainfall seepage and slope stresses are further studied by applying the changing natural/saturated physical and mechanical parameters and pore water pressure values obtained by physical testing and parameter inversion. Moreover, the safety and stability of the highway slope during each stage is computed numerically using the strength reduction method, and the slope failure process, instability-inducing factors and failure mechanism are discussed in detail. The results indicate that the proposed separate simulation and superposition analysis method is effective and of considerable practical value in slope engineering. Additionally, a comprehensive slope stability treatment is suggested, which can be used as a reference for other slope projects experiencing alternating excavation and rainfall disturbance.