The Application Research On Advanced Detection Of Electromagnetic Methods In Coal Mine Roadway Heading Face

Due to the complexity of mine hydrogeological conditions and coal mining historical issues, the coal mine water inrush could be easily caused by the water-bearing, water-conducting structure, and waste water filling road way during the roadway excavation. It could pose a great threat to the safety of coal mining process and coal miners. Therefore, the research and application on tunneling of electrical lead mine detection technology, would have essential and profound impact on coal mining process and water prevention, by timely and accurately predicting water-bearing, water-conducting and water filled tunnel during excavation.Based on literature review and massive advance detection practice in a specific mining area, this study integrated numerical simulation analysis, on-ground and under-ground physical experiments and so on, systematically researched on the mine electrical detection mechanism and technology. In terms of transient electromagnetic method(TEM), by using three-dimensional transient electromagnetic finite difference time domain(FDTD) method, achieved the forward calculation on typical mining model. And by underground experiments, this study discussed how I-beams, U-shaped steel, boring machine, and steel mesh could effect on TEM; and further discussed about “directional” of TE, applicable environment for TEM, the closeness of tunnel face, and the effectiveness of TEM. In the end, it concluded about the construction technology of TEM during excavation. In terms of direct current method(DCM), this essay studied on electrode polarization during advance excavation, selection of measured line position, the current intensity, the electrode spacing and the depth of effective probing. And through theoretical calculations and underground tests, using three-dimensional finite element method DC forward calculation, tested different depth, different water bearing geo-electric model, analyzed abnormal situation and concluded the construction technology of DCM during excavation.This study indicates that the two ways of advanced detection method in roadway excavation have their own features and adapt conditions, i.e. the TEM is “directional”, which means it could detect multi angles; the DCM is more comprehensive, with high accuracy in shallow areas, which offsets the shortage in TEM. However, TEM is more likely to be influenced or interrupted by the environment, especially when massive metal are within limited distance(20 meters) in the tunnel; DCM usually arrange the electrodes in linear shape, which could not effectively work if there is poor power supply or rear distance is too short. Therefore, to solve the problem of advanced detection in roadway excavation, we should utilize both methods and apply them flexibly under different construction conditions.