Erosion Deformation Characteristics of Silt-Fine Sand Interbedded Soil Slope under Rainfall

Kapo in Wensu County, Xinjiang of China, is a high and steep slope formed by fluvial deposition. Highly susceptible to heavy rainfall, it faces prominent erosion hazards and soil loss. Combined with the region’s arid climate and the slope soil’s significant water sensitivity and collapsibility, local slope prevention and control is extremely challenging. To conduct efficient, targeted slope management, this study uses physical rainfall simulation tests to explore surface erosion and deformation characteristics of the area’s interbedded silt-fine sand slopes under rainfall. Results show that rainfall volume and soil properties are the primary drivers of slope erosion. As rainfall duration increases, the slope’s rainwater infiltration rate first rises then declines. Gradually saturated by infiltration, the slope’s erosion resistance weakens, and surface damage intensifies. The sand layer has better permeability than the soil layer; coarse sand also mitigates raindrop-induced splash erosion, which has stronger erosion resistance, erosion initiates in the soil layer beneath the sand layer. Thus, influenced by soil properties and rainfall infiltration, slopes in this region exhibit a retrogressive failure mode: surface erosion, local damage, mid-slope failure, top-slope failure.