矿井瞬变电磁法小线圈装置的电磁场响应特征研究

研究小尺寸且方便在井下安装的瞬变电磁法探测装置，可为掘进巷道随掘随探和预报水害提供新思路。基于全空间瞬变电磁理论，采用三维时域有限元法进行数值模拟，探讨了小线圈激励获得的二次场响应特征和磁芯线圈接收的瞬变电磁响应特征。构建巷道掘进工作面前方含水断层地质-地球物理模型，研究了小线圈装置对含水断层的瞬变电磁响应特征，对比分析小线圈与常规线圈超前探测的效果差异。研究表明:小回线源激励产生的感应电动势衰减规律与常规发射线框对应的感应电动势随时间变化规律相同，磁芯线圈能有效地提高感应信号强度；小线圈装置与常规线圈装置探测应用效果良好，可以有效解释低阻区分布范围，探测结果与巷道掘进验证结果吻合。结合井下现场试验，验证了小线圈装置应用于矿井瞬变电磁法超前探测的适用性和有效性。

Electromagnetic response characteristics of small coil device for mine transient electromagnetic method

The study of the transient electromagnetic detection device with small sized coil and easy installation underground will offer new insights into the real-time dynamic exploration and forecast water-bearing structure in excavation roadway.By drawing on the full-space transient electromagnetic theory, this paper adopted the three-dimensional time-domain finite element method for numerical simulation to explore the characteristics of the secondary field response obtained by small coil excitation and the transient electromagnetic response received by the magnetic core coil.This study constructed a geological-geophysical model of the water-bearing fault in front of the roadway excavation working face, studied the transient electromagnetic response characteristics of the small coil device for the water-bearing fault, and compared the effects of small coil and conventional coil in advance detection.The study shows that : ①the decay law of the induced electric potential generated by the small coil source excitation is the same as that of the induced electric potential generated by the conventional transmitting coil with time, ②the magnetic core coil can effectively improve the induced signal strength, ③the application of both the small coil device and the conventional coil device can effectively explain the distribution range of the low resistance area, ④the detection results match the verification results of the roadway excavation.Combined with the underground field test, this paper verified the applicability and effectiveness of the small coil device applied to mine transient electromagnetic method advance detection.