Rock burst characteristics and mechanism induced within an island pillar coalface with hard roof

Using microseismic monitoring and rock burst records, the burst source, burst energy, damage area, damage scope and damage form etc. were located and analyzed statistically in this paper, and rock burst characteristics were summarized. Meanwhile, by means of theoretical modeling and calculation, rock burst mechanism in island pillar coalface was analyzed from the aspects of rock mass structure and stress state. The results show that all the burst sources are located at the adjacent gob and its edge due to the no breaking of the 60-meter-thick main roof and the secondary-movement of the adjacent gob overburden. With the coalface advancing, the maximum static stress within coal mass rises gradually and comes close to the critical stress. Thus, the superposition of such a high static stress and dynamic stress reaches the critical stress for rock burst, leading to frequent occurrence of rock burst. Both gateways near the designed ending line are the maximum static stress locating area. With a 0-1 m distance between the gateway floor and No. 15-3 coal seam, this area has been damaged repeatedly when rock burst occurred. Because of a higher static stress, the headgate has been damaged 6 times, 3 times more than that of the tailgate. The main damage form of the gateway is floor heaving since the floor is without support and the distance between the floor and coal seam is small. The analysis in this paper may provide a reference to rock burst control with similar conditions.