煤矿工作面背景噪声面波走时层析成像研究

Research on surface wave travel time tomography of ambient noise in coal seam working face

  • 摘要: 煤层工作面断层、陷落柱、薄煤带等地质异常体的存在,严重制约工作面安全生产,因此有必要提前探测清楚其内部构造。地震槽波勘探技术被广泛应用于工作面内部构造成像,并且具有较高的分辨能力,但炸药震源在特定场景下的应用存在局限性,因此有必要发展不依赖炸药震源的工作面内部结构成像技术。与主动震源勘探技术相比,基于背景噪声的成像技术因其不需要主动激发震源,在结构探测中具有显著的优势。华宁煤矿将背景噪声面波层析成像技术应用到工作面内部构造探测的实践表明,利用矿井下机械及采掘活动产生的震动信号,通过弥散波场指标筛选波形数据用于互相关函数计算,可以减小非稳相区噪声源的干扰,获得可靠的面波频散数据。在此基础上,采用面波一步法成像技术直接从频散数据反演三维速度结构,成功获得工作面内部速度结构,并圈定工作面内部异常构造位置。速度成像结果与实际回采揭露的地质异常具有显著的对应关系,验证了背景噪声层析成像方法在工作面构造探测中的可行性和有效性。研究提出的弥散波场筛选技术和面波一步法成像流程为煤矿井下地质构造探测提供了新的技术手段,该方法不需要主动震源,具有绿色探测的优势,可为工作面安全高效回采提供技术支持。

     

    Abstract: The presence of geological anomalies such as faults, collapse columns, and thin coal seams in coal seam working faces severely constrains safe production, making it necessary to detect their internal structures in advance. Seismic in-seam wave exploration technology is widely applied to internal structural imaging of working faces with high resolution capabilities, but the application of explosive sources is restricted in certain scenarios, necessitating the development of working face internal structure imaging technology independent of explosive sources. Compared with active source exploration techniques, ambient noise-based imaging technology has significant advantages in structural detection as it does not require active source excitation. At Huaning Coal Mine, ambient noise surface wave tomography is applied to structural detection in coal mine working faces, whereby vibration signals generated by underground machinery and mining activities are utilized and waveform data are selected using diffuse wavefield indices prior to cross-correlation functions calculation; as a result, interference from non-stationary phase zone noise sources is suppressed and reliable surface wave dispersion data are obtained. Based on this, the one-step surface wave imaging technique is employed to directly invert three-dimensional velocity structure from dispersion data, successfully obtaining the internal velocity structure of the working face and delineating the positions of internal anomalous structures. The velocity imaging results show significant correspondence with geological anomalies revealed during actual mining, validating the feasibility and effectiveness of ambient noise tomography method in working face structural detection. The proposed diffuse wavefield selection technique and one-step surface wave imaging workflow provide new technical approaches for geological structural detection in underground coal mines. This method requires no active sources and offers green detection advantages, providing technical support for safe and efficient mining operations in working faces.

     

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