Influential law of dynamic stockpiling and rainfall infiltration on stability of waste dump slopes

Taking the Hexi Waste Dump of the Shuichang Iron Mine as the study site, this research addresses the susceptibility of loose materials in the dump to induce sliding deformation under the coupled effects of dynamic stockpiling and rainfall. Through theoretical modeling and numerical simulation analysis, the study investigates the influential patterns of heavy rainfall infiltration under three stockpiling conditions using a solid-liquid coupling model incorporating a stockpile stress correction term. The study indicates that under different stockpiling states, increased stockpile height linearly elevates the negative pore water pressure at the crest, inhibiting seepage at the top while promoting seepage in the lower soil layers due to stress redistribution. During the initial rainfall phase, infiltration primarily occurs at the slope surface and crest; during the mid-phase, it shifts to the toe. In the late and final phases, infiltration rates stabilize, with maximum infiltration depths reached at all locations—deepest at the slope surface and shallowest at the crest. Horizontal and vertical stresses and strains in the soil increase progressively with increasing stockpile height, with peak strength reaching its maximum in the toe area of the +220 platform. This comprehensive analysis of the permeability characteristics and stability of loose soil under dynamic stockpiling provides a theoretical basis for the design of waste dumps and their long-term safety assessment.