Study on law and prediction of surface movement and deformation in mountain area under repeated mining of shallow coal seam

In view of the problem of surface subsidence and landslide caused by repeated mining in southwest China. Taking Anshun Coal Mine in Anshun City, Guizhou Province, as the engineering background, the surface subsidence is predicted by using the probability integral method, and then analyzed by using UDEC numerical simulation software and the physical similarity simulation experiment with XTDIC system. The results show that the maximum predicted subsidence value of single coal seam mining is 1.8 m, and the maximum predicted subsidence value under repeated mining is 3.78 m, which is similar to the results of similar simulation experiment and numerical simulation. Through similar simulation experiments, it is found that the initial weighting step of the main roof of Anshun Coal Mine is 32 m, the periodic weighting step is 12 m, and the key stratum caving step is 80 m. Under repeated mining, the first weighting step of the main roof is reduced to 20 m, the average periodic weighting step is reduced to 8 m, and the surface subsidence increases significantly. Through numerical simulation analysis, it is found that the surface subsidence under the original horizon of the key stratum is almost the same as that of the similar simulation experiment. The higher the key strata, the larger the collapse step of the key strata, and the smaller the subsidence caused by the surface.