1. Geotechnical Engineering Research Center,Shandong University,Jinan　 250061,China; 2. College of Resources and Metallurgy,Guangxi University,Nan- ning　 530004,China

隧(巷)道掘进工作面-钻孔瞬变电磁超前探测方法是在隧(巷)道超前钻孔的基础上,将接收传感器置于钻孔之中,沿钻孔不同深度进行测量,形成瞬变电磁响应的深度-时间剖面曲线,进而判定掘进工作面前方是否存在含水构造。物理模拟试验显示:在使用较小发送磁矩情况下,深部很难观测到有效信号;使用较大发送磁矩激发时,晚期时间和深部会出现感应电压方向反号的现象,利于判断异常体的存在,且掘进工作面前方存在高阻或低阻目标时观测曲线在幅值和方向反号时间上均存在明显差异,可以判断掘进工作面前方是否存在异常构造。该方法利用已有钻孔开展探测,不需要增加额外成本,可提高判定灾害源是否存在的精度。

In the tunnel surface-borehole configuration,the receiver is put into the borehole based on the advanced drilling on the tunnel face. With the data acquired in different depths in the borehole,the depth to time profile of tran- sient electromagnetic responses can be obtained to determine the position of the water bearing structures. The physical modeling results show that no valid signals are observed in depth with a small magnetic moment excitation,while the acquired electromotive force are direction reversal in deep and late time with a large magnetic moment excitation. This phenomenon can be used to identify the abnormal bodies. The acquired profiles are obvious different on amplitude val- ue and the reversal time with high or low resistivity target exist. This method will have no additional cost with existing borehole and is very fast in acquiring data. It can improve the accuracy in identifying the disaster sources.

SUN Huaifeng,CHENG Ming,SU Chuanxi,et al. Tunnel face-borehole transient electromagnetic method and its physical experimental stud- ies[J]. Journal of China Coal Society,2017,42(8):2110-2115.