Isolating and Tracking Noise Sources across an Active Longwall Mine Using Seismic Interferometry
Isolating and Tracking Noise Sources across an Active Longwall Mine Using Seismic Interferometry
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DOI：
10.1785/0120220031
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发表时间：
2022-06
影响因子：
3
通讯作者：
Santiago Rabade;Sin‐Mei Wu;F. Lin;D. Chambers
中科院分区：
文献类型：
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作者：
Santiago Rabade;Sin‐Mei Wu;F. Lin;D. Chambers
利用地震噪声监测矿井的地震活动性和结构完整性的能力对于探测和管理地面控制灾害具有重要意义。然而，噪声波场由于诱发的地震和与采矿作业有关的重型机械而变得复杂。在这项研究中，我们调查的性质随时间变化的噪声互相关函数（CCF）在一个活跃的地下长壁煤矿。我们分析了一个月的连续数据记录的地面17检波器阵列与平均站间距为10.200米。为了提取相干地震信号，我们计算每个5分钟窗口的所有台站之间的CCF。对所有5分钟CCF的仔细检查揭示了可以分类分为两组的波形，一组具有强且相干的1-5 Hz信号，另一组没有。使用一个参考站对，我们在统计上隔离每个组内的时间窗口的基础上，每个5分钟CCF和每月堆叠CCF之间的相关系数。与高相关系数相关的每日叠加的CCF显示出明显的时间变化，与采矿活动的进展一致。相反，与低相关系数相关的每日叠加CCF在整个记录期间保持稳定，与预期的持续背景噪声一致。为了进一步了解高相关系数CCF的性质，我们执行2D和3D反投影来确定和跟踪主要噪声源的位置。在CCF确定的震源位置、活跃采矿作业的总体迁移和编目地震事件位置之间的短（5分钟）和长（每日）时间尺度上观察到了极好的一致性。在这项研究中提出的工作流程演示了一种有效的方法来识别和跟踪采矿引起的信号，其中与背景噪声相关的CCF可以被隔离，并用于进一步的时间结构完整性调查。
The ability to monitor seismicity and structural integrity of a mine using seismic noise can have great implication for detecting and managing ground-control hazards. The noise wavefield, however, is complicated by induced seismicity and heavy machinery associated with mining operations. In this study, we investigate the nature of time-dependent noise cross-correlations functions (CCFs) across an active underground longwall coal mine. We analyze one month of continuous data recorded by a surface 17 geophone array with an average station spacing of ∼200 m. To extract coherent seismic signals, we calculate CCFs between all stations for each 5-min window. Close inspection of all 5-min CCFs reveals waveforms that can be categorically separated into two groups, one with strong and coherent 1–5 Hz signals and one without. Using a reference station pair, we statistically isolate time windows within each group based on the correlation coefficient between each 5-min CCF and the monthly stacked CCF. The daily stacked CCFs associated with a high correlation coefficient show a clear temporal variation that is consistent with the progression of mining activity. In contrast, the daily stacked CCFs associated with a low correlation coefficient remain stationary throughout the recording period in line with the expected persistent background noise. To further understand the nature of the high correlation coefficient CCFs, we perform 2D and 3D back projection to determine and track the dominant noise source location. Excellent agreement is observed on both short (5-min) and long (daily) time scales between the CCF determined source locations, the overall migration of the active mining operation, and cataloged seismic event locations. The workflow presented in this study demonstrates an effective way to identify and track mining induced signals, in which CCFs associated with background noise can be isolated and used for further temporal structural integrity investigation.