Deformation characteristics and soil erosion effect of concave loess slope on main cross-section of coal mining subsidence basin

A deep understanding of the erosion loss effect induced by coal mining subsidence on the slope scale is an important scientific basis for the accurate prevention and control of erosion loss in the coal mining area in the middle reaches of the Yellow River. Taking the typical loess mining subsidence basin in Northern Shaanxi as the research area, through FLAC^3D numerical simulation, the deformation characteristics of concave loess slope on the main cross-section of the mining subsidence basin are revealed from the perspective of the triadic coupling of "slope position (slope edge, center, margin), natural slope gradient (5°, 15°, 25°, 35°, 45°), and slope aspect (downslope, upslope)". Based on the CSLE model and the empirical model, the soil erosion effect of the concave loess subsidence slope is clarified. The results show that under the triadic coupling of "slope position, natural slope gradient, and slope aspect", coal mining subsidence leads to an increase in the gradient of concave loess slopes, with slope position being the key controlling factor. The increase of slope gradient increases first and then decreases with the transition of slope position from margin to center, and reaches the maximum of 11.85% under the conditions of "slope edge position + natural slope gradient of 5° + downslope aspect". Whether in the scale of annual erosion rainfall or typical field erosion rainfall, coal mining subsidence will lead to the increase of soil erosion modulus of concave loess slope, and the increase will reach the maximum under the condition of "slope edge position + natural slope gradient of 5°+ downslope aspect", which is 11.40% and 10.14% respectively. Slope position is still the key control factor. It is suggested that the layout of underground coal mining face should be adjusted and optimized according to the relative position relationship of surface concave loess slope in coal mining subsidence area as the pre-mining precise prevention and control strategy of erosion loss effect in loess mining subsidence area of Northern Shaanxi in the middle reaches of the Yellow River.