Transient electromagnetic perspective technology in the ultra-long coal mining face

Abstract

The ultra-long coal mining face has the advantages of high recovery efficiency and low production cost; however, the widening of the coal face poses the difficulty of detecting the hidden geological bodies inside the coal face, and using conventional geophysical methods gives rise to imprecise detection results. Therefore, this paper proposes a transient electromagnetic perspective technology based on the conventional mining transient electromagnetic method. A long rectangular loop is used as the transmitting source in one coal mining tunnel of the coal mining face, and it is received in the opposite coal mining tunnel. This method is characterized by a long detection distance and high construction efficiency. Firstly, the paper used numerical simulation to investigate the spread of the transient electromagnetic field from the long rectangular loop source in both a uniform full-space model and a full-space laminated model. This showed the transient electromagnetic field propagation law and the effect of the coal seam thickness. Then, we analyzed the transient electromagnetic perspective signal characteristics of typical geological structures and gave the all-time apparent resistivity calculation method. Conclusively, the feasibility of this method is ultimately confirmed by the analysis of the measured data. Also, the research results provide a new technological approach to detecting hidden geological structures in the ultra-long coal mining faces.