采动影响下逆断层冲击地压矿震时空分布规律分析

Analysis of spatial and temporal distribution laws of mine earthquake induced by thrust fault coal bumps under mining disturbance

为了分析开采扰动下逆断层冲击地压矿震活动时空分布规律,根据G-R地震活动幂次分布规律,结合现场微震监测数据与数值模拟方法,通过矿震活跃度b值以及地震矩值M0对井下矿震活动分布规律以及高震级事件能量释放水平进行了分析。研究结果表明:在时间跨度上,井下矿震事件频次分布规律符合G-R分布规律,b值越小,高震级矿震事件在整个矿震事件中频次越高,对工作面冲击危险性影响越严重。b值受原岩应力、开采扰动、断层性质的影响:最大与最小主应力差值越大、开采速率越快、断层倾角越小、落差越大,b值越小;逆断层地震矩M0在空间分布上有着明显的差异性。靠近高位岩层附近断层面区域的地震矩值为整个断层面上的峰值区域,随着工作面不断逼近断层面,断层面上的高峰值区域会不断增大且向下部区域蔓延,使得整个断层面上的地震矩不断增大。断层面地震矩值的增大意味着可释放能量水平不断提高,对工作面造成的扰动也会更加剧烈,进一步增大冲击地压事故的危险性。

In order to analyze the spatial and temporal distribution laws of mine earthquake induced by thrust fault coal-bump under mining disturbance,according to the power distribution law of G-R seismic activity,combined with the in-situ monitoring micro-seismic data and numerical simulation method,the frequency and energy release levels of high-magnitude events in underground mine earthquake activities are analyzed by b value and seismic moment M 0.The results show that:the distribution law of underground micro-seismic activity is similar to the seismic distribution law of the crust.The activity of micro-seismic events is related to the b value.The smaller the b-value is,the higher the frequency of high-magnitude mine shock event in the entire mine shock events,and the more serious the impact on the working face.The analysis finds that the b value is affected by the in-situ stress,mining disturbance,and fault properties.Specifically:increasing the maximum and minimum principal stress difference,mining rate,fault throw or decreasing fault dip angle will reduce b value,resulting in high activity of micro-seismic activity,inducing coal-bump,and threatening the safe mining.There is obvious difference in the spatial distribution of thrust fault seismic moment M 0.Under the influence of mining disturbance,the seismic moment in the upper area of the fault is relatively large.As the working face is approached,the overall value of the seismic moment is continuously increasing,and the area of high peak seismic moment is continuously expanding from top to bottom.The increase of the seismic moment value on the fault means that the level of releasable energy continues to increase,and the corresponding disturbance to the working face will be more intense,further increasing the risk of coal bumps.