冲击地压频发区矿震破裂机制与震源参量响应规律
Response characteristics of rupture mechanism and source parameters of mining tremors in frequent coal burst area
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摘要: 矿震是冲击地压孕育及诱发的重要影响因素,研究矿震震源破裂机制对完善冲击地压致灾机理至关重要。为有效分析矿震震源破裂机制与震源参量响应特征,基于相对矩张量反演原理提出以震源群为单位反演矿震震源机制,并针对煤矿应用背景构建了反演矩阵,推导了反演所需最低射线数与震源数条件,优化了矿震震源破裂类型判识方法,提高了反演精度与效率,统计分析了褶皱构造区、深埋断层构造区以及高应力大巷煤柱区等3个冲击地压频发区矿震破裂机制与震源参量的响应规律。结果表明:矿震震源参量与破裂机制与其地质构造情况、震源层位以及应力环境等相关。褶皱构造区顶板型强矿震以拉张破裂占主导,煤体中强矿震以剪切破裂占主导,拉张型与剪切型矿震的震源破裂强度与应力调整程度差异较小,而拉张型矿震的扰动规模更大;深埋断层构造区拉张型矿震具有更强的破裂强度,剪切型矿震具有更大的扰动规模;高应力大巷煤柱区矿震震源类型以剪切破裂为主导,煤柱(体)极易在顶底板的夹持下沿应力优势方向发生连续性剪切破坏,剪切型矿震震源参量平均值(除视应力)明显高于拉张型矿震,表明剪切型矿震时冲击危险性显著高于拉张型矿震。不同条件下震源参量与破裂机制响应特征可为强矿震的精准判识和力学机制研究提供参考。Abstract: Mining tremors are the essential factor for the formation and initiation of coal bursts. It is crucial to investigate the fracture mechanism of the mining tremors to integrity the coal burst mechanism. An inversion mechanism based on the source group is proposed based on the relative moment tensor inversion principle to effectively analyze the rupture mechanism and response characteristics of source parameters. Based on the background of the application in coal mines,the inversion matrix is constructed firstly. In addition,the minimum ray number and source number conditions are deduced,and the identification method of source rupture type of mining tremors is optimized,which improves the inversion accuracy and efficiency. The mechanism of seismic rupture mechanism and the response law of source parameters in the fold structure area,deep buried fault structure area,and high stress roadway coal pillar area are analyzed statistically. The results show that the strong mining tremors’ focal parameters and rupture mechanism are related to the geological structure,focal layer,and stress environment. The tensile fracture is dominant in the roof,and the shear fracture is prevalent in the coal mass belonging to the fold structure area. The difference of source rupture strength and stress adjustment degree between tensile type and shear type is slight,while the disturbance scale of tensile type is more extensive. The tensile type has more muscular rupture strength,and the shear type has a larger disturbance scale. Seismic source types in high stress area coal pillar dominated by shear fracture are easily along the coal pillar under the roof,and floor of the clamping stress along the edge direction occurs shear damage continuity. The average shear source parameters (in addition to the apparent stress) significantly higher tensile type mining tremors show that shear when mining tremors risk is considerably higher than tensile type mining tremors. Source parameters and rupture mechanism characteristics under different conditions can provide a reference for accurate identification and mechanical mechanism research of strong mining tremors.