Mechanism of Rock Burst and Its Dynamic Control Measures in Extra-Thick Coal Seam Mining from below the Residual Coal Seam to below the Gob

Abstract

AbstractIn this paper, aiming at the mechanism and regulation of overburden breakage induced by mining from the residual coal seam to the mined-out area, taking Kuangou Coal Mine as the background, the mechanism of rock burst from the residual coal seam to the mined-out area was revealed through the laws of overburden breakage and its structural evolution, ground pressure appearance, and energy release. The impact risk area is determined by the comprehensive evaluation results of multimethod face impact risk. A roof pressure relief and impact prevention control method using large-diameter empty hole combined with advanced deep hole blasting was formed, and the field verification was completed. The research results show that an obvious inverted trapezoid structure is formed when the residual coal seam of the W1123 working face is mined to the working face under the gob, which is related to the energy release caused by the occurrence of periodic pressure and the rupture of the critical layer. The shock ground pressure of the working face predicted by the neural network is mainly weak shock and medium shock risk; the numerical simulation analysis shows that the shock hazard area of the W1123 face below the solid coal is mainly located in the lower part of the working face near the transportation roadway and the shock below the W1145 gob. The dangerous area is about 32~72 m away from the return air alley. Through the plastic zone distribution and the orthogonal test, the optimal pressure relief scheme for large-diameter holes is 12 m in depth, 300 mm in diameter, and 2 m in spacing. When the blasting angle is consistent with the overlying rock fracture angle obtained from the simulation experiment, a better pressure relief can be achieved. When the bursting angle is consistent with the simulated overburden rupture angle, it has a better pressure relief effect. The pressure relief and anti-scour control method of large-diameter holes combined with advanced deep hole blasting reduce the daily average vibration frequency, energy, incoming pressure, and step distance of working face mining. The safe and efficient mining has a certain reference effect.