Study on the destruction law of physical and shear properties of soil in mining disturbance

Underground mining activities can easily trigger surface subsidence and cause damage to surface soil. However, there is still a lack of studies on damaged soil, restricting ecological remediation in mining-induced subsidence regions to a certain degree. Focusing on the particular example of No. 4 Mine in Yili, Xinjiang, China, this study comprehensively combined field sampling, laboratory experiments, and data analysis to investigate the variation rules of basic physical properties and shear characteristics of soil samples. The latter had different subsidence degrees (0, 0–20, 20–40, and above 40 cm) and various depths (0– 10, 10–20, 20– 40, 40–60, and 60–80 cm). The experimental results show that: First, the natural density and dry unit weight of shallow soil in the serious-subsidence region were more significantly affected by mining-induced subsidence than the conditions in the deep layer, which also dropped with the increase in subsidence degree (with a mean drop rate of 7%). Second, serious subsidence could greatly counteract the positive effect of slight and moderate subsidence on the soil shear strength, with a drop rate of up to 30.7%. Third, compared with soil physical indices, mining-induced subsidence more easily affected shear strength indices. In particular, the soil samples taken from 0 to 10 cm depth in the slight subsidence area and 60–80 cm depth in the moderate subsidence area were most significantly affected by mining-induced subsidence, with PCA comprehensive scores of over 1.5. The present study can con-tribute to gaining in-depth knowledge of the damage characteristics of surface soil under mining-induced subsidence and provide a theoretical foundation for formulating reasonable coal mining strategies and ecological protection measures.