Rock burst still occurs after de-pressure blasting of bottom coal in the driving face of thick coal seam.Taking the driving face of thick coal seam in Liuhuanggou Coal Mine,Xinjiang,as the engineering background,the failure mechanism of bottom coal pressure relief induced by strong vibration in driving face of thick coal seam is studied by means of field investigation,theoretical analysis and numerical simulation.The results show that,due to the excavation,the coal body shear failure during the unloading process of the surrounding rock causes strong vibration,and the energy of the vibration wave is mainly absorbed by the loose bottom coal,which eventually leads to the impact of the bottom coal.The energy criterion for the failure of bottom coal pressure relief induced by strong vibration is proposed.Based on calculation,the height of bottom coal throwing Hc is determined to be 1.26 m in the heading face of the thick coal seam in the sulfur ditch,which verifies the accuracy of the theoretical analysis,and the critical source energy EZ of 13.7 kJ the pressure relief bottom coal impact is obtained.Finally,the disturbance effect of different source energy on the pressure relief bottom coal is simulated by FLAC3D,when the total energy of the source is 22,32 and 42 kJ,the maximum vertical velocity of the bottom coal is 4.32,6.91 and 16.65 m/s respectively,and the maximum vertical displacement of the bottom coal is 0.11,0.57 and 1.40 m respectively.The vertical velocity of bottom coal increased with the increase of the total energy of the source.With the increase of the dynamic load time,it increased rapidly and then decreased rapidly and finally decayed to zero.The displacement of bottom coal increased with the increase of the total energy of the source,and the increasing trend gradually slowed down with the increase of the dynamic load time,and reached the maximum when the dynamic load time is 3/5 cycles,which assists in verifying the accuracy of the theoretical analysis.
thick coal seamrock burstvibration wavethick bottom coalpressure relief failurebottom coal impact energy index
维普
万方数据
