Effect of Underground Coal Mining on Slope Morphology and Soil Erosion

Underground coal mining will cause large-scale surrounding rock movement, resulting in surface subsidence and irreversible deformation of surface morphology, which would lead to geological disasters and ecological environment problems. In this paper, FLAC 3D numerical model is built based on the natural slope gradient, slope type, and included angle between the slope and working face, and their influences on the change of surface morphology and soil erosion caused by underground coal mining is studied. Research results show that the change of slope gradient caused by underground mining decreases with the increase of natural slope gradient, while slope length has opposite laws; different slope types have different changes of slope morphology. The order of slope types corresponding to gradient changes is mixed slope < uniform slope < concave slope < convex slope; the length of the concave and uniform slope decreases, and the convex and mixed slope length increases. When the included angle between the slope and working face is 0° ≤ α < 90°, the underground mining will cause the natural slope gradient increase, the change of the slope gradient will increase with the rise of the angle, the slope length will decrease, and the rate of decrease will be reduced with the increase of the angle. Coal mining will cause the increasing of the runoff and erosion modulus of slope, mainly runoff modulus.