Researches On The Application Of Transient Electromagnetic Method In Coal Mine

In the production of the coal mine tunneling, water-bearing structure and goaf with water hidden in front often lead to mine water inrush accidents, which pose a great threat to coal mine safety production and the safety of workers. It makes a great sense to water prevention and safety production in coal mine to study non-contact time domain mine transient electromagnetic detection technology and forecast water-bearing structure and goaf with water timely and accurately. With the advantages of constructing conveniently and efficiently, reflecting sensitively and large detection range and so on, Mine transient electromagnetic detection technology is used in many mining area in our country. However,because the research on theory of mine transient electromagnetic lags behind relatively, the effect, large low resistance metal body underground having on the detection results is not very apparent. In this paper, numerical simulation and downhole physical experiment are used to study the theory and technology of mine transient electromagnetic detection. The main results and innovations are as follows: (1)When the transient electromagnetic method applies to coal mine engineering detection, the signal received by apparatus can be regarded as the superposition of signal in two conductive half space, for there are induced eddy current both in front and behind of the wire frame.Learning from the basic theory formula of transient electromagnetic field in whole space, by using the CST, a German TEM simulation software, it’s response curve of whole space is simulated in surrounding rock with different resistivities in homogeneous medium in this paper. And according to the geological problems which need to be resolved via advanced prediction of TEM, the characteristics of such curve response of low resistivity bodies with different sizes, resistance and distances from the wire frame are studied, which can guide the practical application of mine transient electromagnetic detection in theory.(2) Through the experiment in the underground field, characteristics of the effects which large metal boring machineries with low resistance have on advanced detection results of the transient electromagnetic are summarized and analyzed, and the construction distance to avoid its interference is given too.