Study on surface subsidence characteristics of coal mining under thick loose layer

Based on the general deformation law of surface subsidence, the characteristics of the final deformation of the surface subsidence and the dynamic deformation characteristics of the surface subsidence under the thick loose layers were studied, and the systematic surface subsidence monitoring was carried out in the third mining area of Yunjialing Mine, and the characteristics of the final movement and deformation of the surface subsidence, the calculation of the angular parameters, the subsidence rate of the ground surface, the velocity of ground subsidence and the duration of ground movement were analyzed and studied.The results show that the subsidence area is wide, and the full mining angle is 70° to the left, 61° to the right, 57° to the boundary angle, 81° to the lower boundary angle, and the strike angle is 67°.The sinking speed is fast and the active phase is only 15 days, accounting for 6% of the total surface movement time.The maximum subsidence velocity lag distance is 146 m and 143 m respectively, and the subsidence amount is smaller but the cycle is longer in the recession stage.The above results show that when the mining is repeated under thick loose layer, the subsidence of the ground surface is directly proportional to the degree of mining, the subsidence period of active period is short, and the period of the decline stage is long.