瞬变电磁法在煤矿超前地质勘查中的应用

Application of transient electromagnetic method in advanced geological exploration of coal mines

煤矿覆盖层厚度较大,加大了地质勘查难度。瞬变电磁法受地形影响较小,为此,研究了瞬变电磁法在煤矿超前地质勘查中的应用,勘查前对WTEM-1瞬变电磁系统进行检验标定。通过地质勘查试验,确定施工频率与线框边长,对3个线圈实施一致性测试。依据试验区已知矿床的分布情况与地形特点布设测线;使用沿地形缓起伏的测量方式采集数据,利用高斯滤波进行预处理后,通过转换感应电动势数据为视电阻率数据完成解释处理,从中圈定矿体异常区域进行解析分析。应用结果表明,试验区的测线剖面电性分层明显;前2道测线处不存在偏低或偏高的视电阻率,后3道测线处均存在偏低的视电阻率;在后2道测线处存在偏高的视电阻率,其中低磁异常是火山角砾岩,高磁异常是石英闪长岩侵入体。

The thick overburden of the coal mine increases the difficulty of geological exploration.The transient electromagnetic method is less affected by terrain,therefore,the application of transient electromagnetic method in advanced geological exploration of coal mines is explored.Inspection and calibration of the WTEM-1 transient electromagnetic system before investigation were conducted.The construction frequency and side length of wire frame through geological survey test were determined,and conformance testing for three coils was conducted.Set up survey lines based on the distribution and terrain characteristics of known mineral deposits in the experimental area.Collect data using a gently undulating measurement method along the terrain,preprocess it using Gaussian filtering,and complete interpretation processing by converting induced electromotive force data into apparent resistivity data,delineating abnormal areas of the ore body for analytical analysis.The application results show that the electrical stratification of the survey line profile in the experimental area is obvious;there is no low or high apparent resistivity at the first two survey lines,while there is a low apparent resistivity at the last three survey lines;there are relatively high apparent resistivity at the last two survey lines,of which the low magnetic anomaly is volcanic breccia and the high magnetic anomaly is quartz diorite intrusion.