Similar Material Simulation Test of Overlying Strata Characteristics of Isolated Working Face Mining with Thick-Hard Strata

The overlying strata spatial structure of isolated working face under thick-hard strata is complex, and the overlying strata movement is drastic. Rock burst in this kind of isolated working face is easy to occur under the influence of mining depth and geological structure. Aiming at the safety problems caused by the overlying strata movement deformation of the isolated working face under deep mining, one similar model of the thick-hard strata on the working face is built. The overlying strata structure and its evolution characteristics in the mining process of working face are studied by using a similar material simulation test. The results show that the overlying strata structure above the isolated working face is long-arm T-type spatial structure in the vertical section, and the coal body at the corner of isolated working face forms the stress concentration region. In addition, with the increase of the mining range, the coal pillar in the upper and lower sections compress and sink, resulting in the gob range increases, and the overlying strata re-move on both sides of isolated working face, the long-arm T-type overlying strata fracturing after reaching the limit of suspension, causing the isolated working face instability. It can be seen that the long-arm T-type structure is prone to large scale fracture movement of the key strata, and the risk of inducing strong rock burst is high. Therefore, when mining by strip method, the mining range of the working face on both sides of isolated working face should be increased, or the technology of cutting roof and pressure relief should be adopted to avoid the formation of long-arm T-type spatial structure above the isolated working face, so as to reduce the occurrence of rock burst.