Relationship between support and strata in extra-thick coal seam fully-mechanized sublevel caving mining based on high precision microseismic monitoring technology

Based on the high-precision micro-seismic monitoring technology, the theories of rock mechanics pressure and the field macro scenes, and the relations between stratum movement and support on the extra-thick fully mechanized top-coal caving face are studied. The results show that the basic load of the support includes such forces as the top coal more than 10 meters thick, the lower immediate roof about 30 meters thick and the upper immediate roof about 20 meters thick under normal circumstances. The main roof in front of the work face is forced to break the lower strata after its fracture and causes impact load on the support. It is the main reason that the design support capacity of 13000 kN / frame is crushed. Accordingly, the selection of the support of the fully mechanized top-coal caving face should consider the basic ability of the support, which can bear the forces from the top coal and the direct uplift. Some measures such as decrease of distance of support roof and increase of support extension should be taken so as to reduce the impact on the support.