基于双源CT联合反演的深部大巷煤柱冲击危险区域探测

Detection of rock burst risk areas in coal pillars of deep roadways based on joint inversion of dual-source CT

  • 摘要: 震动波CT反演技术是冲击地压危险性预测和日常防冲监测、效果检验的重要手段,但在实际应用中,主动CT反演实施成本高,无法进行连续实时监测,且大范围探测受限,难以动态跟踪应力变化;被动CT反演的震源位置误差大,分辨率低,层析成像质量受限于自然微震的频率与能量。针对该问题,提出了一种适用于深部大巷煤柱冲击危险预测的主被动双源CT联合反演策略。首先实施主动CT探测,布置人工震源与接收阵列,采用走时层析成像方法,反演获得高精度三维初始波速模型;在主动探测基础上,联合下一相近时段由微震监测系统记录到的被动震源及其射线走时信息,构成联合反演数据;以主动CT反演获得的高精度三维初始波速模型作为联合反演初始模型,再次进行走时层析成像,并根据反演结果预测煤柱冲击危险区域。在赵楼煤矿7305工作面开展工程应用,对比分析了主动CT、被动CT及主被动双源联合CT的反演结果。结果表明,双源CT联合反演策略有效补充了单一方法的覆盖盲区,提高了高波速区识别精度。微震事件验证结果表明,超过80%的震源位于双源CT反演识别的高波速区内,说明该策略的可行性与准确性。

     

    Abstract: Seismic wave CT inversion technology is an important method for rock burst hazard prediction, as well as routine rock burst prevention monitoring and effectiveness evaluation. However, in practical applications, active CT inversion has high implementation costs, cannot achieve continuous real-time monitoring, and is limited in large-scale detection, making it difficult to dynamically track stress changes. Passive CT inversion suffers from large errors in source location and low resolution, and the quality of tomographic imaging is constrained by the frequency and energy of natural microseismic events. To address this problem, a joint inversion strategy based on active-passive dual-source CT suitable for predicting rock burst hazards in coal pillars of deep roadways is proposed. First, active CT detection was implemented by arranging artificial seismic sources and receiver arrays, and a high-precision three-dimensional initial velocity model was obtained using the travel-time tomography method. Based on the active detection, the passive seismic sources recorded by the microseismic monitoring system during the subsequent time period, along with their ray travel-time information, were combined to form the joint inversion dataset. The high-precision three-dimensional initial velocity model obtained from active CT inversion was used as the initial model for the joint inversion. Travel-time tomography was performed again. The rock burst risk zones in the coal pillars were predicted according to the inversion results. An engineering application was carried out at the working face 7305 of Zhaolou Coal Mine, and the inversion results of active CT, passive CT, and active-passive dual-source joint CT were comparatively analyzed. The results showed that the dual-source CT joint inversion strategy effectively complemented the coverage blind zones of a single method and improved the identification accuracy of high-stress zones. Verification results based on microseismic events showed that more than 80% of the seismic sources were located within the high-velocity zones identified by the dual-source CT inversion, demonstrating the feasibility and accuracy of this strategy.

     

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