149 / 2023-07-01 00:59:56

Directional characteristics of electromagnetic radiation generated by coal and rock fracture

Electromagnetic radiation,Fracture-induced,Directional characteristics

It is well acknowledged that the fracture of rocks (especially brittle rocks) is accompanied by electromagnetic radiation signals. And as a monitoring method, electromagnetic radiation has been rapidly developed with broad prospects, but the research on the vector nature of the fracture-induced electromagnetic field is relatively insufficient. Based on the self-developed three-axis electromagnetic antenna, the directional characteristics of low-frequency electromagnetic radiation generated by coal and rock fracture are analyzed using the principle of vector synthesis. The signals on the three directions have obviously different waveform characteristics in the time domain, but have a similar distribution in the frequency domain. Based on the signal auto-correlation function and cross-correlation function, the difference of the signal energy and rise time of the three channels is obtained. The results show that the signals of each channel of the three axes can be regarded as the three components of the magnetic vector. The changing law of the direction angle is consistent with the electromagnetic field vector generated by the oscillating electric dipole. The intensity and correlation of the synthesized signal at different measuring points have an obvious relationship with the position.