Research on prevention and control of rock burst in entry with suspended roof structure

In order to solve the problem of rock burst prevention and control of suspended roof structure along gob, a method for the prevention and control of rockburst based on the engineering weak structure was proposed according to the specific coal and rock conditions of entry. Based on the occurrence conditions of rock burst in the entry with suspended roof, taking the suspended roof structure along the gob side as the main research object, the roof fracture analysis, parametric analysis and mechanical model establishment and analysis were carried out, and finally it was determined that the hanging span l of the hanging roof structure was the leading factor leading to rock burst in the roadway along gob of the overhanging roof structure. Through the dominant factors and based on the spatial structure characteristics of the surrounding rock of the roadway along the gob side, five strong structural regions of the overhanging roof structure ( region A ), the roof of the roadway along the gob ( region B, C ), the coal body of the roadway along the gob side ( region D ) and the near-field coal and rock mass of the roadway ( region E ) were delineated, and the prevention and control method of the rock burst of the engineering weak structure body with the weakening of regional A blasting as the main prevention and control means was proposed;according to the structural characteristics of the area and the purpose of prevention and control, mainly for the strong structural areas A, C, D, and E, three specific engineering weaknesses were formulated, including the weakening of the overhang structure, the restoration of roadway section and the coupling between the roof defect and coal seam sponge. In order to verify the effectiveness of the prevention and control technology, taking the specific stope conditions of a mine as the object, 〖JP2〗the prevention and control of engineering weak structures was carried out on the site, and the drill cutting method was used to test the prevention and control effect of rock burst. The research shows that based on the study of dissipation mechanism of weak structure, the effective prevention and control of rock burst are realized through the ′weakening′ of overhanging roof structure, the ′weakening′ of coal body and part of roof along gob roadway, and the working face is recovered safely. Through on-site monitoring, it is found that the maximum cuttings volume is 2.6 kg/m at the depth of 1-3 m, 2.8 kg/m at the depth of 4-7 m, and 5.4 kg/m at the depth of 7-12 m, all of which do not exceed the critical standard value, and the danger of rock burst is eliminated.