Research on the movement characteristics of overlying strata in deep coal seam high-level roadway cutting block pre splitting blasting coal mining

The existence of thick and hard roof often leads to the failure of traditional blasting pressure relief technology to meet the anti-scour and pressure relief engineering of deep mines. How to realize the active pressure relief and anti-scour work of thick and hard roofs in different layers has become the focus of attention. Based on the roof cutting and pressure relief project of 8302 high-level roadway in Xinjulong Coal Mine, this paper innovates the pre-splitting blasting pressure relief method for the key strata of hard roof in deep coal seam, and develops the roof breaking and pressure relief technology of high-level roadway cutting block pre-splitting blasting matching the spatial position of disaster-causing key strata. The necessity and rationality of roof breaking blasting in high-level roadway are verified by two-dimensional geomechanical model test and GDEM numerical simulation, which reveals the fracture instability mechanism and stress evolution characteristics of hard roof caused by high-level roadway blasting, accurately controls the fracture step of rock strata and weakens the energy intensity of collapse impact. The two sets of experimental results are compared and analyzed. The results show that in the model experiment of high pre-splitting blasting mining without high pre-splitting blasting, the separation and collapse of rock strata occur between the coal seam and the thick and hard roof, and the thick and hard roof forms a simple supported beam structure to block the crack propagation. In the mining model experiment after high-level pre-splitting blasting, with the advancement of the working face, the stress evolution law of the overburden rock can be roughly divided into the stage of slow stress rise, the stage of stress step-down, the stage of stress drop and the stage of stress recovery. There is a large displacement in the rock layer above the coal seam, and the hard roof collapses in an orderly manner, and the deformation and crack propagation also occur in the rock layer above it, which realizes the effect of cutting block pre-splitting blasting pressure relief. Finally, field tests are carried out to evaluate the new anti-scour and pressure relief technology with the help of microseismic monitoring data. The research results can provide some theoretical guidance for the anti-scour and pressure relief project of thick and hard roof, and have certain reference significance for the prevention and control project of rock burst in deep mine.