Application of Ground and Underground Transient Electromagnetic Methods in Detecting Water-rich Areas in Coal Mines

In order to investigate the water-rich situation of coal seam IV-2 in the 4218 working face of Anyuan Coal Mine and avoid water damage, transient electromagnetic detection work combining ground and underground was carried out throughout the entire working area based on the basic principles of transient electromagnetic method and underground transient electromagnetic method. Based on the transient electromagnetic method has the characteristics of low resistance anomalies, convenient construction, large exploration depth, and the ability to accurately reflect the range of water content anomalies, and the underground transient electromagnetic method has the characteristics of high construction efficiency, small volume effect, and more reliable determination of anomaly positions. The ground transient electromagnetic method is used to delineate the distribution range of water hazards from the plane, and then the underground transient electromagnetic advanced detection technology is used to accurately delineate the water-rich situation in front of the tunnel. Based on geological and drilling data, the corresponding relationship between each layer and the electrical layer in the apparent resistivity cross-section map of ground transient electromagnetic method is analyzed. It is inferred that the relatively low resistance areas at the top and bottom of coal seam are likely to be caused by water-rich sandstone fissure. Therefore, one moderately water-rich area and six weakly water-rich areas are delineated in the entire area. The underground transient detection results at the position 49 meters before Q6 point in the auxiliary transportation trough of the 4218 working face show that there are four low resistance abnormal areas at the top plate 30° along the layer, and bottom plate 45° at the head position. Compared with the ground interpretation abnormal areas, there are three overlapping areas, the overlap rate is high. The results indicate that the comprehensive detection of ground and underground transient electromagnetic methods can effectively improve the accuracy of detecting waterrich areas in coal seams, providing a basis for mine water hazard prevention and control.