Analysis of migration and failure regular pattern of overlying strata in different mining heights

In this paper, the H-mine is taken as the research background, and the critical layer theory is used to determine the reasonable height of the "three belts" of the overlying strata in different mining heights. This thesis uses FLAC3d numerical simulation to analyze the law of failure in roof movement under different mining height conditions. The research shows that the height of the fracture zone increases abruptly with the increase of the mining height due to the influence of the key layer. Each mutation indicates that a key layer is broken to form the masonry beam structure. In the numerical simulation, the plastic zone of the working face has a "saddle-shaped" distribution with high ends and low middle. With the increase of mining height, the differences between the plastic zone range above the mining boundary and the central plastic zone is reduced. From the bottom to the top, the roof is divided into several regions, that is, tensile failure region, the shear tension failure region, shear failure zones and undamaged areas. With the increase of mining height, the pre-stress concentration factor and the lateral stress concentration coefficient increase linearly, and the lateral stress concentration factor is slightly lower than the pre-stress concentration factor. The peak position increases as the height increases. (paper)