Key Technologies for Dynamic Imaging of Disaster-Causing Concealed Water Bodies in Underground Coalmines Based on Transient Electromagnetic Method

Received: 15 October 2019 Accepted: 8 January 2020 The concealed water bodies are potential sources of disasters in underground coalmines. However, it is difficult to detect these water bodies in an accurate manner. To overcome the difficulty, this paper designs a high-power imaging system for transient electromagnetic method (TEM) in coalmines. Specifically, the shutdown period of emission current was reduced to 12μs with high-current reverse clamp inductance technology; the secondary field signals were collected and the background noise was reduced to 1μV through equivalent sampling, segmented amplification, and superimposed denoising; the least squares imaging and attitude angle was fused for the first time to realize the rapid imaging of the disaster-causing concealed water bodies in front of the heading face in underground coalmines. The proposed system was applied to detect and continuously track the water-rich worked-out sections on the same layer and on the roof, as well as the water in collapse columns in the excavation direction and in the heading face. The results show that our system can accurately detect 74.1% of disaster-causing concealed water bodies. This research provides new insights into the prevention and control of water disasters in underground coalmines.