Energy characteristics of AE signal frequency band during coal rupture in mines with gas

In order to analyze gas's influence on AE band energy during coal rupture under loadingꎬ with structural coal as research objectꎬ uni ̄axial compression test was carried out by using self ̄developed gas ̄ containing coal test device. Thenꎬ signal processing method of fast Fourier transform (FFT) and wavelet packet analysis was used to obtain characteristics of AE band energy during coal rupture under different gas 中 国 安 全 科 学 学 报 China Safety Science Journal 第30卷 2020年 pressure. The results show that the greater gas pressure isꎬ the larger main frequency of AE signal isꎬ the narrower frequency band isꎬ and spectrum transforms gradually from a complex multi ̄peak form to a single peak form. When three is gasꎬ with the increase of loading stressꎬ frequency band enriches and spectrum shifts to left gradually. As gas pressure changesꎬ energy of 2􀆰 92-4􀆰 38 kHzꎬ 4􀆰 38-5􀆰 84 and 7􀆰 3-8􀆰 76 kHz changes significantly while that in 2􀆰 92-4􀆰 38 kHz is basically same as the sum of 4􀆰 38-5􀆰 84 and 7􀆰 3-8􀆰 76 kHzꎬ showing an opposite trend. When stress of structural coal increasesꎬ 4􀆰 38-5􀆰 84 and 7􀆰 38􀆰 76 kHz indicate the largest increase and decrease of energy respectively. 2􀆰 92-4􀆰 38 kHz and 4􀆰 385􀆰 84 kHz can be used as characteristic frequency bands to study damage of structural coal under loading in mines with gas.