Investigating on the mechanism and prevention of rock burst induced by high intensity mining of drainage area in deep mines

The deep mine working faces in Shaanxi and Inner Mongolia mining areas are generally characterized by water-rich roof and high-intensity mining,and obvious rock bursts have emerged when the mining passes the drainage areas of roof. Through the investigation of the accident scene and analysis of monitoring data,it was found that this kind of rock burst is closely related to the drainage water and mining intensity of the mining face. By establishing the mechanical model for estimating the abutment pressure of the working face after water drainage,the stress evolution law before and after water drainage in water-rich area was studied. Then,an abutment pressure distribution model under high-intensity mining was established,and the influence of the mining advance speed on the lead abutment pressure of the working face was studied. It also made a comprehensive analysis of the effects of drainage and high-intensity mining on the stress distribution law of the working face,revealing the mechanism of rock burst under high intensity mining of drainage area in deep buried working face. Research results are as follows:the stress concentration caused by water drainage has become stable before mining,and the pressurized zone and pressure-relief zone,as the static stress source of the coal seam and its roof,were formed. At the same mining time,the faster the mining advance speed was,the longer the hanging distance of basic roof was,the more elastic energy was accumulated before fracture,the closer the peak of lead abutment pressure was to the coal wall,the greater the peak was,and the faster the deformation rate of roadway surrounding rock in the corresponding position was. When the working face was rapidly mined through the pressurized area, the stress superposition easily exceeded the critical value of rock burst, and the energy released brought about the rock burst of coal wall. The research results were applied to the prevention of rock burst during the mining of the water-rich working face in deep mines,and a rock burst prevention method for the dynamic regulation of mining advance speed in the drainage area was put forward. Based on the micro-seismic monitoring and theoretical calculations,the critical mining advance speed was formulated to ensure safe mining on the working face. The research results provide a technical guidance for the rock burst prevention and the mining advance speed determination during the mining of the water-rich working face in the deep mines of Shaanxi and Inner Mongolia mining areas.