开采扰动下断层面库仑应力及诱发矿震时空演化特征

为研究煤矿开采扰动下断层面库仑应力演化特征及诱发矿震时空分布规律，基于赵楼矿1303综放工作面生产地质条件，理论分析了断层面库仑应力影响因素，采用数值模拟及岩石力学试验方法，探讨了逆断层下盘工作面向断层开采过程中，断层面不同位置库仑应力变化规律，并分析了现场矿震监测数据时间统计特征及震源空间分布规律。结果表明:开采扰动因素σx，σy，τxy(等于τyx)，断层倾角θ及断层面摩擦因数μ综合决定了断层面库仑应力f，当开采扰动及断层摩擦因数确定时，取df/dθ=0可确定断层活化失稳最危险角；断层构造破坏了采动应力扰动圈的对称性及位移扰动圈的连续性；岩石力学试验及数值模拟结果均表明沿断层面岩层高位点先于低位点受到采动影响，且过断层前随断层与工作面距离减少，断层面活化失稳危险先升高后降低；工作面过断层前后，矿震日震动频次由20次/d上升至35次/d，而日震动平均能量由22 kJ下降至4 kJ，表明工作面过断层前高能量矿震较多，对围岩扰动剧烈，过断层后扰动较平缓；同时工作面过断层前后，断层面上矿震震源集中区由高层位岩层向低层位岩层转移。

Characteristics of tremor time-space evolution and Coulomb stress distribution along the fault during workface excavation

In order to study the Coulomb stress variation along a fault face and the tremor distribution features under the mining disturbance,the elements which have effects on Coulomb stress of fault face were theoretically analysed on the basis of the geological and mining conditions of 1303 top-caving workface in Zhaolou Coal Mine,China.With numerical simulation and laboratory test,the Coulomb stress of different location along a reverse fault face was calculated as the distance between mining face and fault face decreasing.Additionally,the in-situ tremor data was collected and statistically analysed.The results show that the Coulomb stress (f) of a fault face point is determined by the mining disturbance (including σx,σy,τxy and τyx),the angle of the fault (θ) and the frictional coefficient (μ) of the fault face.If the mining disturbance and frictional coefficient are fixed,the most dangerous angle of the fault for sliping could be obtained by df/dθ=0.Stress disturbance circle and displacement disturbance circle are formulated as the coal excavating,and the symmetry of the stress disturbance circle and the continuity of the displacement disturbance circle are broken because of the existence of fault.Numerical simulation data and laboratory test data all show that the upper zone of the fault face is influenced by the mining firstly,and the slipping liability of fault increases first and then decreases as the workface mining forward to the fault face.The daily frequency of tremors was about 20 per day as the workface located in footwall and increased to approximately 35 per day when the workface located in the hanging wall.However,the average energy for each tremor declined from 22 kJ before workface reach the fault to 4 kJ after the workface passes the fault,which demonstrates that the tremor disturbance is severe as the workface moving forward to the fault,what is more,the concentration zone of tremor focus transfers from upper zone of the fault to down zone when the mining face mining through the fault face.