断层活化的地应力判别准则及诱发冲击地压的典型微震特征

采用Anderson断层模型,推导得出了煤矿井下断层区域应力累积水平的计算指标μm,该指标只与实测最大和最小主应力有关,μm值越大表明区域应力累积水平越高,当μm值达到断层摩擦极限状态或亚摩擦极限状态的应力累积水平μ0时,将可能引起断层冲击地压的发生。通过对40个矿井、120个测点的地应力数据分析表明,采动作用下诱发断层冲击地压的概率和强度与矿井地应力类型、采深H和μm值存在密切关系:地应力类型为σVσHσh方位,即使H和μm达到很大也不会发生;只有地应力类型为σHσVσh和σHσhσV时才有可能诱发断层冲击地压,且相比σHσVσh,地应力类型为σHσhσV所需的临界值H0和μ0更小。根据龙家堡煤矿地应力测试结果,判定该矿具备断层冲击地压发生危险。根据微震监测数据的分析,提出了断层冲击地压发生的4典型微震特征,即微震事件的高能特征、丛集现象、前震-主震-余震序列和上盘效应。

Analysis of fault activation induced rock burst risk based on in-situ stress measurements

Through theoretical derivation,this paper presented a calculation index μ m for the evaluation on the regional stress accumulation level of faults in three directional stress condition.Research shows that the index μ m is only related to the measured maximum and minimum in-situ stress,the greater the index shows the higher level of accumulation on the regional stress.The analysis of the in-situ stress data of 40 coal mines and 120 test holes showed that whether the fault rock burst happen depends on stress type,mining depth H and index μ m.If stress type is σV>σH>σh,even though H and μ m especially are very large,the fault rock burst will never happen.The fault rock burst only happen in σH>σV>σh andσH>σh>σV,and when the stress type isσH>σh>σV,the critical value of H 0 and μ 0 are smaller.On the basis of in-situ stress results in Longjiapu coal mine,this paper evaluates the fault rockburst danger.The authors proposed four typical microseismic characteristics of fault rockburst.They are the characteristics of high-energy microseismic event,cluster phenomenon,foreshock main-shock aftershock sequence and hanging wall effect.