Research on distribution characteristics and main controlling factors of rock burst in steeply inclined coal seams

Rock bursts often exhibit regional characteristics, and the geological conditions of mines are important factors influencing these regional characteristics. To investigate the impact of complex geological conditions on the risk of rock bursts, this study takes Wudong Coal Mine as the engineering background and employs methods such as case analysis, numerical simulation, theoretical derivation, and field monitoring to study the regional distribution characteristics of rock bursts in steeply inclined and extremely thick coal seams and their controlling factors. Historical case analysis indicates that rock burst damage in Wudong Coal Mine is primarily concentrated within 1 500-2 000 m range along the working face; within this range, areas with narrower interlayer pillars experience more severe rock burst damage, while regions with wider pillar are less affected. Numerical simulation based on a complex three-dimensional geological model of Wudong Coal Mine reveals that during alternating mining of two coal seams in steeply inclined and extremely thick coal layers, concentrated stress within one seam can be transmitted through the interlayer pillar to the other seam, further increasing the concentrated stress and energy in the coal seam. Theoretical derivation indicates that interlayer pillars are the primary stress transmission paths. Narrower pillar widths result in shorter transmission distances, greater stress amplification in the coal seam, and higher rock burst risk. Field monitoring data show that in areas with wider interlayer pillars, energy release from surrounding rock is dominated by low and medium level micro-seismic events, and few high level micro-seismic events. Conversely, in areas with narrower interlayer pillars, high-energy micro-seismic events are significantly more frequent, and energy release from surrounding rock is more intense, leading to a notable increase in rock burst risk. The research result reveals that the width of intermediate rock pillar is the main controlling factor of the regional distribution of rock burst, and the width of rock pillar is negatively correlated with the risk of rock burst.