Roadway transient electromagnetic method has been widely used in detecting mine water disaster ahead of roadway excavation face. Due to the strong mutual inductance between transmitting-receiving coils, the early-stage data obtained by this method are seriously distorted and the effective resolving time of transient electromagnetic (TEM) field is greatly lengthened, which leads to the shallow blind area of exploration. To improve the ability of transient electromagnetic testing system and to resolve short-range geoelectric abnormalities in front of the roadway excavation face, we provided the expression functions of the primary TEM field and the receiving system’s impulse response, restored the data recorded by instrument theoretically and compared the differences between the recorded data and the pure secondary TEM data. We found that the factors, including the increase in the current switch-off time, the decline in the receiving coils’ inherent resonant frequency, the enlargement in the mutual inductance between transmitting-receiving coils, and the mismatch in the receiving circuit’s damping resistance and so on, could significantly affect the early-stage TEM data, which results in a great delay in the effective resolving time. Based on the above findings, we improved the TEM testing system, compared the monitored data obtained using the original and improved testing system. It demonstrates that the improved testing system shortened the effective resolving time, which greatly enhanced the reliability of early-stage data and efficiently resolved the geoelectric abnormal zones closer to the roadway excavation face.

巷道瞬变电磁法已广泛应用于巷道开挖工作面前方矿井水害检测。由于发射-接收线圈之间的强互感，该方法得到的早期数据失真严重，瞬态电磁（TEM）场的有效分辨时间大大延长，导致勘探盲区较浅。为提高瞬态电磁测试系统的能力，解决巷道开挖工作面前短程地电异常，我们提供了一次TEM场和接收系统脉冲响应的表达函数，从理论上还原了仪器记录的数据，比较了记录数据和纯二次 TEM 数据之间的差异。我们发现这些因素，包括电流关断时间的增加、接收线圈固有谐振频率的下降、收发线圈间互感的增大、接收电路阻尼电阻的不匹配等，都会显着影响早期的 TEM 数据，导致有效分辨时间有很大延迟。基于以上发现，我们改进了TEM测试系统，比较了使用原始测试系统和改进测试系统获得的监测数据。表明改进后的测试系统缩短了有效解析时间，大大提高了早期数据的可靠性，有效解析了靠近巷道开挖面的地电异常带。接收线圈固有谐振频率的下降、收发线圈间互感的增大、接收电路阻尼电阻的失配等都会对早期TEM数据产生显着影响，从而导致有效解决时间大大延迟。基于以上发现，我们改进了TEM测试系统，比较了使用原始测试系统和改进测试系统获得的监测数据。表明改进后的测试系统缩短了有效解析时间，大大提高了早期数据的可靠性，有效解析了靠近巷道开挖面的地电异常带。接收线圈固有谐振频率的下降、收发线圈间互感的增大、接收电路阻尼电阻的失配等都会对早期TEM数据产生显着影响，从而导致有效解决时间大大延迟。基于以上发现，我们改进了TEM测试系统，比较了使用原始测试系统和改进测试系统获得的监测数据。表明改进后的测试系统缩短了有效解析时间，大大提高了早期数据的可靠性，有效解析了靠近巷道开挖面的地电异常带。以及接收电路阻尼电阻的失配等，都会对早期TEM数据产生显着影响，导致有效分辨时间有很大延迟。基于以上发现，我们改进了TEM测试系统，比较了使用原始测试系统和改进测试系统获得的监测数据。表明改进后的测试系统缩短了有效解析时间，大大提高了早期数据的可靠性，有效解析了靠近巷道开挖面的地电异常带。以及接收电路阻尼电阻的失配等，都会对早期TEM数据产生显着影响，导致有效分辨时间有很大延迟。基于以上发现，我们改进了TEM测试系统，比较了使用原始测试系统和改进测试系统获得的监测数据。表明改进后的测试系统缩短了有效解析时间，大大提高了早期数据的可靠性，有效解析了靠近巷道开挖面的地电异常带。比较了使用原始和改进的测试系统获得的监测数据。表明改进后的测试系统缩短了有效解析时间，大大提高了早期数据的可靠性，有效解析了靠近巷道开挖面的地电异常带。比较了使用原始和改进的测试系统获得的监测数据。表明改进后的测试系统缩短了有效解析时间，大大提高了早期数据的可靠性，有效解析了靠近巷道开挖面的地电异常带。