基于微震事件“时-频-能”特征分析的工作面隐伏断层预测研究

Prediction of hidden faults in working face based on time-frequency-energy characteristic analysis of microseismic events

为了弄清煤矿井下无法被有效探测的隐伏断层,依据大量的微震事件分析,提出了使用微震监测预测工作面隐伏断层探测的方法,采用离散傅里叶变换(DDT)、一维离散小波变换(DWT)和能量密度法实现微震事件的时域、频域及能域曲线之间的转化。研究结果表明,微震事件的时域曲线呈现波峰少、震动持续时间长、尾波发育的特征;频域曲线呈现频段集中于0~20Hz、单峰的特征;能域曲线呈现"缺震"区间增多、波动时间变长的特征时,工作面前方可能存在隐伏断层。据此分析了星村煤矿3307工作面微震事件波形曲线的突变原因,推断工作面前方存在隐伏断层,工作面后续揭露的F2隐伏断层验证了此推断。

Influenced by the accuracy of geophysical prospecting,some small faults in coal mine can not be detected. By analyzing a large number of microseismic events,a detecting method for hidden fault of working face using microseismic monitoring is proposed,in which DDT,DWT and energy density methods are used to transform the time domain,frequency domain and energy domain curves of microseismic events. The research shows that,in the following conditions,a hidden fault might exist in front of the working face: in the time domain,when there are few peaks of microseismic events,long duration of vibration,developed coda;the frequency domain curve concentrates in the frequency band of 0 ~ 20 Hz with single-peak characteristic;earthquake deficiency section increases and fluctuating time prolongs in the energy domain curve. Based on this,reason for the abrupt change of microseismic event waveform curve in 3307 working face in Xingchun Coal Mine is analyzed. It is inferred that there are hidden faults interfering with the propagation of vibration wave in front of the working face.The F2 hidden faults exposed subsequently in the working face has verified this inference.