Study On The Law Of Surface Movement And Deformation Caused By Repeat Mining Under Thick Loose Layer

With the increasing shortage of mineral resources, repeated mining has become an important way of mining, which has important theoretical and practical significance.In this paper, a mine in Huainan as the research background to establish surface movement observation station. On the basis of field measurement, we deal with the one first mining working face and the other five repeated mining working surface observation data of surface movement. Combined with the similar material simulation and numerical simulation analysis to clear and definite the laws of surface subsidence movement under the condition of repeated mining of thick loose layer. Under the influence of repeated mining in thick and loose layer, the overburden stress is increased dramatically and the critical layer is broken, and also the "potential subsidence" is activated, finally all of those conversion to surface subsidence; The maximum value of the ground surface, the maximum curvature and the maximum horizontal deformation are all increased; The starting distance is obviously decreased and the lead influence angle, the maximum subsidence velocity lag angle, the boundary angle and the moving angle are reduced; The initial stage of the surface movement is shorter; the active period is longer, and the recession period is slightly shorter. The total surface subsidence is greater than the sum of the subsidence of each coal seam mining alone, and the total amount of surface displacement is larger than the sum of horizontal displacement of each coal seam mining; the subsidence coefficient increases; the horizontal displacement coefficient decreases, and the range of surface movement increases. At the same time, based on the analysis of similar material simulation experiment and numerical simulation results, to discuss the control action of key strata of overlying strata to the rock movement and reveal the inner mechanism of the surface subsidence coefficient greater than 1.The result of the study is to provide reference for the study of surface movement of repeated mining in the future.