煤矿褶皱构造区冲击矿压震源机制

Focal mechanism of rockburst in folded region in coal mine

为实现对褶皱构造区冲击矿压震源机制的有效分析,基于震源机制矩张量反演方法,在优化震动波远场位移及破裂面产状求解方法的基础上,对甘肃华亭矿区砚北煤矿250204工作面回采期间冲击矿压震源破裂类型、破裂面产状及视应力等地震学参量进行系统分析,揭示了砚北煤矿褶皱构造区冲击矿压震源机制。研究结果表明:工作面回采扰动影响下,褶皱构造区冲击矿压震源破裂类型以拉张破裂为主,其矩张量以非双力偶部分占主导,表现为水平挤压构造应力、超前支承压力共同作用下煤岩体的应力释放;震源破裂面产状有明显分化趋势,小倾角(<35°)震源破裂面走向多垂直工作面推进方向,而大倾角(>35°)震源破裂面走向多平行于工作面推进方向且倾向实体煤一侧;褶皱构造区冲击矿压震源辐射能量和地震矩基本分布在一包络线内,随震源辐射能量增大,其地震矩大小分布更加集中;通过震源视应力计算,得到了回采扰动下工作面及其周边应力演化情况,与冲击矿压震源时空分布及巷道冲击显现结果基本吻合。

Exploitation in longwall 250204 at Yan-bei coal mine within fold region had led to the occurrence of very high seismic activity,where 50 rockbursts took place from April 2011 to May 2013. To determine the cause of rock- burst in fold region, the research employed the method of seismic moment tensor inversion which provides the parame- ters of focal mechanism （ percentage share of its components ： isotropic, uniaxial compression or tension, shear compo- nent;trend and dip of nodal planes, etc. ） based on the analysis of geological and mining conditions. The test showed that the type of ruptures were all distinguished as tensile failure which represented that the stress-release of loaded coal and rock mass was caused by the multi-effect of horizontal tectonic stress and abutment pressure. The joints occurrence of ruptures had an obvious tendency of differentiation, and the trends of ruptures with dip angle below 35° were almost normal to the advancing direction of working face, while the other ruptures with angle above 35° were more or less par- allel to advancing direction. The seismic moment and radiated energy of rockbursts were all distributed in an envelope,and the value of seismic moment had an obviously distributing center with radiated energy growth. The distribution of apparent stress was consistent with the actual situation of mined area which high-stress region concentrated in the axial part of syne｜ine structure.