Mechanisms and micro-seismic response characteristics of deep-hole pre-cracking to reduce the risk of rock burst in the mining roof of island working face
Mining in island working faces poses a high risk of rock bursts,and roof pre-cracking is an effective mitigation technique.This study investigates the No.1105 island working face in the upper coal seam 3 of Gaozhuang Coal Mine.Using theoretical analysis,numerical simulations,and on-site micro-seismic monitoring,the mechanism of rock bursts in island working faces was analyzed,and the effectiveness of roof pre-cracking in reducing rock burst risk was assessed.The results show that the multi-arch structure formed by overburden rock in the adjacent goaf areas facilitates pressure transmission,while the instability of the"voussoir beam"structure induces strong dynamic loads,which are the primary causes of the high rock burst risk.A mechanical model for local pressure arches was established to analyze their mechanical properties,and instability criteria were derived.The roof pre-cracking blasting method reduces rock burst risk by destroying the local pressure arch structure and disrupting the"voussoir beam".This disruption obstructs the pressure transmission path,reduces the high bearing pressure zone,and minimizes the risk of strong dynamic loads caused by beam instability during mining.On-site micro-seismic monitoring data confirm the effectiveness of roof pre-cracking,demonstrating a significant reduction in rock burst risk.
island working facemulti-pressure arch structuredeep-hole roof pre-crackingrock burst risk reduction mechanismmicro-seismic response characteristics
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