基于震源机制与定位误差校准的冲击地压危险预测方法

Prediction method of coal burst risk based on focal mechanism and location error calibration

  • 摘要: 冲击地压智能监测技术迅速发展大背景下,如何利用海量微震监测信息挖掘震源破裂性状并将其应用于冲击地压的预测预警或防控是未来研究的重点与难点。为解决目前微震群破裂机制聚合规律挖掘不充分、震源机制反演技术难以直接应用于冲击地压的预测预警难题,采用理论分析、数值仿真等手段研究建立基于震源机制与定位误差校准的冲击地压危险预测方法。以内蒙古某冲击地压矿井大能量矿震事件频发2215工作面为研究背景,总结了煤矿微震波形数量有限、噪声影响大、反演效率要求高的特点,比较分析了不同矩张量方法反演震源机制的特点及优缺点,确立了混合矩张量反演法更适用于煤矿应用场景;2215工作面顶板破断诱发事件以拉剪以及压剪破坏为主;大能量事件发生前微震事件剪切成分占比不超过40%,顶板破断主导的微震事件走向角主要分布于3°~80°以及150°~270°,倾角主要分布于70°~90°,存在明显的集聚特征;基于煤矿常见的震源破裂机制及定位误差分析了微震事件聚合的可能性并建立了微震聚合准则,构建了基于震源破裂机制及定位误差校准的危险预测方法及指标;预测实例结果表明考虑震源破裂机制及定位误差后可显著增强微震异常聚合区的识别;微震数据较为完整情况下,基于震源破裂机制及定位误差校准的危险预测指标IP阈值设置为0.7时可实现对不同破裂类型大能量事件的准确预测。

     

    Abstract: Under the background of the rapid development of intelligent coal burst monitoring technology, how to use massive seismic monitoring information to investigate source rupture and apply it to the prediction, early warning, or prevention of coal burst is the focus and difficulty of future research. To solve the problems of insufficient investigation of seismic clustering fracture mechanism aggregation law and overcome the difficulty of direct application of seismic source mechanism inversion technology to the prediction and early warning of coal burst, the theoretical analysis and numerical simulation methods are used to establish a prediction method of coal burst risk based on seismic source mechanism and location error calibration. Taking the 2215 working face with frequent high magnitude seismic events in a coal burst mine in Inner Mongolia as an example, this paper summarizes the characteristics of the limited number of seismic waves, large noise impact, and high inversion efficiency. Also, it compares and analyzes the characteristics, advantages, and disadvantages of different moment tensor inversion methods, and establishes that the hybrid moment tensor inversion method is more suitable for coal mine application scenarios. The statistical results of the rupture mechanism of high magnitude events in the 2215 working face show that the main inducing events of roof rupture are a tensile shear failure and compressive shear failure. The shear component statistics of seismic events before the occurrence of high magnitude events show that the proportion is not more than 40%. The occurrence statistics of source rupture surface show that the strikes of seismic events dominated by roof breaking are mainly distributed in the range of 3°−80° and 150°−270°, and the dips are mainly distributed in the range of 70°−90°, with prominent agglomeration characteristics. Based on the common source rupture mechanism and location errors in the coal mine, the possibility of seismic event aggregation is analyzed, and the criteria of seismic aggregation are established. The risk prediction method and index based on the source rupture mechanism and location error calibration are constructed. The results of prediction examples show that the identification of seismic anomaly aggregation areas can be significantly enhanced by considering the source rupture mechanism and location error. When the seismic data is relatively complete, the IP threshold of the risk prediction index based on the source rupture mechanism and location error calibration is set to 0.7, and the accurate prediction of high magnitude events of different rupture types can be achieved.

     

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