Predicting The Mining-induced Subsidence At Huangsha Mine Using Discrete Element Method

The rock damage caused by underground mining will develop to the surface. It will induce the surface subsidence and geological disasters. In this paper, Huangsha Mine is the research background. A 3D geological model is established based on the Discrete Element Method(DEM). And then the method is used to predict the rules of the surface subsidence and rock movement according to the 3D geological model and the good rock and joint parameters which are chosen by the orthogonal test.The main work and achievements are as follows:(1)By using the mapping modeling section of Rockmodel, which is independently developed by us and the 3D discrete element software 3DEC, the 3D initial model is established in accordance with the complex formation structure of Huangsha Mine. Then according to the survey report, ‘the mining procedures under buildings, railroads and water bodies’ and ‘the classification standard of engineering rock mass ’, the structural planes in the study area are added by using the software 3DEC to form the calculation model.(2)Based on the further mining subsidence results, the initial physical and mechanical parameters of the rocks and joints are determined. In combination with the monitoring data of the surrounding mining area, the best parameters are chosen by the orthogonal test of deformation and strength parameters of rocks and joints, for the target of the surface subsidence and horizontal movement coefficient.(3)On the basis of the effective model and parameters, the movement rule of the rocks until the surface is predicted. Huangsha Mine belongs to the inclined seam. The rocks mainly squeeze to the mined-out area along the normal of the formation interface. With the increase of the mining depth, the surface subsidence value is smaller. But the surface subsidence value is different at the place where the faults exist. It reflects as the sinking steps. The surface is nearly a bowl basin parallel to the mining boundary. The surface horizontal movement displacement along the strike of the coal seam is bigger than the one along the inclination. And the velocity is faster along the strike. The cracks only appear at the boundary of the subsidence basin at first. With the increase of mining area, the cracks gradually increase.