Experimental study on the exploration of coal mine goaf by dynamic source and fixed reception Roadway-Borehole TEM detection method

Transient electromagnetic advanced detection method is an effective way to explore goaf which regards as a vital threat to coal mine safety and miner’s life. But its application effect is influenced by the roadway environments. This paper presented an operating method which adopts a rotated transmitting terminal located in roadway orifices and three-component receiving terminal located in down-hole. By analyzing the feature of down-hole data using 3D FDTD, this paper presented a technology to synthesize and adjust the three-component down-hole data along with the normal direction. The decline phase’s completely period apparent resistivity,after the peak point of down-hole data,was cal- culated using binary search algorithm. Different hole depth data,in 3D numerical model,was processed to isolated and superimposed imaging. The imaging results showed that it has acquired favorable effect in exploring goaf in front of the driving face. In order to test the practicability and availability of this operating method in detecting goaf’s shape,char- acteristics and dimensions,the author’s research group has conducted an engineering test in Shanxi’s coal mine. The research showed that dynamic source and fixed reception roadway-borehole TEM detection method is a great combina- tion of underground geophysical exploration technology and drilling technology,and makes them supplement to each other. It is an effective application in goaf detection.