Field Test and Structural Stability Analysis of Multi-stage Slope Based on Seepage Coupling Theory

This study takes the slope engineering of the Guangdong North Expressway as the background, and studies the impact of rainfall infiltration on the stability of high slopes through on-site monitoring, data analysis, and model construction. Firstly, based on BC theory, the mechanical calculation model of landslide rainfall is established, and the mechanical formula of slope mechanical properties and Factor of safety considering rainfall process and rainfall infiltration process is derived. Then, by constructing a Fluid–structure interaction numerical calculation model considering the seepage characteristics and mechanical state evolution of the slope, the movement of pore water in the slope under different rainfall intensities and the evolution of the mechanical state and displacement characteristics of the slope were studied. Research has found that the mechanical and numerical calculation models in this article are highly consistent with the actual site conditions, and there may be two potential sliding surfaces in the K738+995 section. The potential sliding surface of K738+910 section is located at a depth of 7 m below the first level platform and 3 m below the third level platform; There may be two potential sliding surfaces in K738+658 section, one is located at the interface between silty clay and sandy clay (9 m below the top of cutting), and the other is mainly located at the interface between sandy clay and completely weathered andesite porphyrite; The surface layer of the slope is silty clay and sandy clay, and the underlying layer is fully strongly weathered andesite porphyrite and moderately weathered dacite. Completely strongly weathered andesite porphyrite is soft, easy to soften and disintegrate when encountering water, and joint fissures are developed. The surface of some cracks is contaminated with iron and manganese, resulting in uneven weathering. The rock is relatively soft and the rock mass is broken. Due to the recent continuous heavy rainfall, the water content of the surface soil of the slope gradually increases and tends to saturation, increasing the self-weight of the slope soil.