Research On Flow Frequency Electromagnetic Signal Reception Technologies Of Precursor To Coal And Gas Outburst

In this paper, we study the attenuation rules of coal and gas outburst's precursory lowfrequency electromagnetic signal traveling in the coal seam based on the theoretical analysises,experiments, numerical simulations and field applications, then design a low frequency barmagnet antenna which sensitive band and effective frequency range have been tested. Combiningwith the influence factors of production process, we introduce an effective method to receive lowfrequency electromagnetic signal in mining working face and apply the monitoring and locating incoal mine. Based on the research, the paper establishes a planar waveguide model andexperimental system of low frequency electromagnetic signal penetrating the coal and rock seam,which is similar to the real conditions. We also test the penetration performence of the designedlow frequency magnetic bar antenna with different frequencies and intensities on differentgranularities of coal samples. Comparing with the attenuation rules under vacuum, we obtain theattenuation rules of low frequency electromagnetic signal from coal petrography in the coal seam.Furthermore the attenuation attribution of low frequency electromagnetic signal in drivage facehas been simulated by CST software through different parts, frequencies and intensities. The lowfrequency electromagnetic signal monitoring and layout of antennas were determined combiningwith the influence factors of production process. As the application, we employed ZDKT-1systemto monitor abnormal electromagnetic and locate the outburst source in blasting process. This paperfirstly proposes a point of view that low frequency electromagnetic signal can be utilized toforecast dynamic disasters and provides theoretical and technical support for outburst prediction ofmining face.