Study on Low Frequency Characteristics of Electromagnetic Signal in the Process of Coal Rupture

Using low-frequency electromagnetic radiation experiments of coal and rock, the paper received low-frequency electromagnetic radiation signal through Briquette experiments under uniaxial loading experiments. Effectively low frequency electromagnetic signals are obtained through removing high-frequency noise based on HHT reduction principle, the paper analyzed amplitude and pressure relationship of effective low-frequency electromagnetic radiation signal and drew the energy variation laws of low-frequency electromagnetic signal and frequency range. Analysis results showed that amplitude and energy of low frequency electromagnetic signal became larger in the Briquette compaction stage; in the coal linear elastic stage, low-frequency electromagnetic signals were paroxysmal generated, however, its energy was weaker; in briquette rupture stage, low-frequency electromagnetic signal amplitude and energy was dramatically strengthened. Frequency range of low-frequency electromagnetic radiation signal was located between 0 to 18 Hz, electromagnetic signal generated in the process of briquette rupture had a good low frequency characteristics and the changing amplitude and energy could well reflect the situation of briquette rupture.