矿井瞬变电磁透视探测技术响应特征研究与应用

Research and application of response characteristics of mine transient electromagnetic perspective detection technology

  • 摘要: 针对大采长/超宽工作面内部隐蔽地质异构体常规地球物理探测难的问题,揭示了对侧发射接收的瞬变电磁透视探测电磁响应机制。采用理论研究、数值模拟和实测数据分析相结合的研究方式,对瞬变电磁透视探测技术电磁场扩散特征、数据影响机制以及探测能力进行了详细研究,研究结果表明:受地空边界的影响,全空间长条形发射回线瞬态电磁场扩散与半空间电磁场扩散不同,全空间状态下感应电动势极值长期位于发射线圈中心位置,无法直接沿用地面“烟圈效应”进行处理解释;对侧发射接收的瞬变电磁透视早期数据主要受一次磁场的影响,具有较高的左右低阻异常分辨能力和探测能力,晚期数据与同侧发射接收数据产生机制相同,为发射线圈附近产生的二次场相互感应扩散形成,其分辨能力和探测能力相对较弱;相较于同侧发射接收的瞬变电磁法,对侧发射接收的瞬变电磁透视技术结合早晚期数据,可以很好的区分低阻异常体相对于发射线圈和接收点的空间位置;低阻异常体越靠近发射线圈,对侧接收的早期数据受到的影响越大,晚期数据影响时间段有所增加,但影响程度越小,越靠近接收点所在巷道,其影响特征相反,以此可以粗略判断低阻异常体沿工作面切向的位置。早晚期数据相结合的瞬变电磁透视探测技术,能更加精细地解译工作面内部及附近隐蔽突水地质异构体的空间信息。

     

    Abstract: Aiming at the difficulty in detecting concealed geological isomers using conventional geophysical method in ultra-wide coal working face, the electromagnetic response mechanism of mine transient electromagnetic (TEM) perspective detection with opposite side emission and reception is revealed in this study. The electromagnetic field diffusion characteristics, data influence mechanism and detection capability of transient electromagnetic perspective detection technology are studied in detail by means of theoretical research, numerical simulation and analysis of measured data. The results show that the transient electromagnetic field diffusion of the full-space elongated emission loop is different from that of the half-space electromagnetic field diffusion due to the boundary between ground and air. In the full-space state, the extreme value of the induced electromotive force (EMF) is located in the center of the emission coil for a long time, which cannot be interpreted directly by using the ground ‘smoke ring effect’. The early transient electromagnetic perspective data transmitted and received on the opposite side are mainly affected by the primary magnetic field and have high resolution and detection ability of left and right low resistance anomalies. The late data and the same-side transmitting and receiving data have the same generation mechanism, both them are formed by mutual induction and diffusion of secondary fields generated near the transmitting loop, and their resolution and detection ability are relatively weak. Compared with the transient electromagnetic method, this technology can distinguish the spatial position of the low-resistance anomaly relative to the transmitting loop and the receiving point by combining early and late data. The closer the low resistivity anomaly body is to the transmitter loop, the greater the impact on the early data received at the opposite side, and the impact time period of the late data increases, but the degree of influence is smaller. On the contrary, the closer it is to the receiving point in the roadway, the opposite the impact characteristics are. Therefore, the approximate position of the low-resistance anomaly body along the working face can be roughly determined. The transient electromagnetic perspective detection technology, which combines early and late data, can more accurately interpret the spatial information of hidden water inrush geological isomers which are inside and near the working face.

     

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