Study on the structure and strata behavior regularity of repeated mining overburden of close-distance shallow buried coal seam group

This paper studies the collapse structure, plastic failure regularity, and overburden movement regularity in the mining process of the Shallowly Buried Coal Seam (SBCS) group in the Yulin area using physical similar material simulation, computer numerical simulation, and theoretical analysis. The objective of the present article is to explore the strata behavior regularity of the SBCS group, taking the engineering geological conditions of Hongliulin Coal Mine as the sample. According to the results, when the lower coal seam of the SBCS group is mined, the initial stress step increases, and the periodic stress step decreases compared to the upper first coal seam. During the mining of the lower coal seam, there is an extreme collapse span in the interlayer rock formation: the process induces the activation of the collapsed roof in the goaf of the upper coal seam, and the overall sinking phenomenon occurs. The dynamic stress is obvious. The roof stress is significant in passing through the upper coal seam's residual coal pillar (CP) into the lower coal seam. The CP is at a certain distance, and the residual CP is violently unstable and sinks the strata behavior regularity. The interlayer rock layer forms an inclined shear staggered fracture zone along the coal wall. The research results provide a theoretical method for controlling mine stress and green and safe mining in the SBCS group of coal production enterprises.