Research on the impact of ground subsidence of varying degrees caused by underground coal mining on soil erodibility

Underground coal mining activities are highly prone to triggering ground subsidence. Currently, research on the impact of multiple factors—including varying degrees of ground subsidence caused by underground coal mining and associated changes in soil mechanical composition—on soil erosion in the Yili region of Xinjiang remains relatively limited. Therefore, this study selected the No. 4 Coal Mine in Yili, Xinjiang as the research area. Soil samples were collected from areas with varying degrees of ground subsidence, and their mechanical composition and organic matter content were measured. The EPIC model was applied to analyze the impact of subsidence severity on soil erodibility. Results indicate that subsidence increases the sand fraction mass, promoting sandy soil formation. Compared to non-subsidence areas, subsidence zones exhibit an increase in sand content ranging from 0.33% to 4.02%, with the most pronounced sandification occurring in severely subsided areas. Concurrently, subsidence causes a decline in soil organic matter content, with reductions ranging from 0.18 g·kg–1 to 3.96 g·kg–1. Under the combined influence of the mining area’s unique geological environment and subsidence morphology, the soil erodibility K-value in the study area showed a clear negative correlation with subsidence severity. The soil K-values in mild, moderate, and severe subsidence areas decreased by 0.59%, 0.73%, and 2.82%, respectively. This study provides a basis for identifying soil erosion zones and predicting erosion rates caused by underground coal mining in the Yili region of Xinjiang.