Determination of the damage range in the toe zone of gentle piedmont slopes based on hydraulic mechanisms

This study presents a novel hydro-mechanical framework for assessing damage development in the toe zone of gentle piedmont slopes by integrating seepage analysis and beam theory. SEEP3D numerical simulations are performed to characterise pore-water pressure and confined water distributions under variable slope geometries, dimensions of water-blocking structures, and rainfall characteristics. Based on confined water distribution, the slope toe region is classified into two distinct zones. Zone A, featuring a triangular uplift pressure distribution, is analysed using a simply supported beam model, whereas Zone B, with a trapezoidal uplift pressure distribution, is idealised as a cantilever beam. The results reveal that slope length and the embedded depth of water-blocking structures exert the most significant control over seepage characteristics. Rainfall duration and intensity also govern confined water distribution, with V-shaped and incremental rainfall patterns exerting the most prominent impacts on seepage fields. Deformation and cracking behaviours within both zones are systematically investigated to quantify damage extent at the slope toe. The combined numerical simulation and mechanical modelling approach established herein provides a quantitative and mechanistic tool for evaluating slope stability and supporting landslide mitigation in gentle piedmont areas.