瓦斯环境中煤体破裂AE信号频带能量特征研究

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

为分析瓦斯环境对煤体受载破裂过程中的声发射(AE)频带能量的影响,以构造煤体为研究对象,利用自行研制的含瓦斯煤体试验装置进行单轴压缩试验,采用快速傅里叶变换(FFT)与小波包分析的信号处理方法,得到不同瓦斯压力下的煤体破裂AE频带能量特征。结果表明:瓦斯压力越大,煤体破裂产生的AE信号主频越大,频带越窄,频谱逐渐由复杂多峰形态转变为单峰形态;瓦斯环境下,随着受载应力的增加,频带逐渐丰富,频谱逐渐左移;当瓦斯压力变化时,2. 92~4. 38、4. 38~5. 84、7. 3~8. 76 kHz等3个频带的能量变化趋势较为明显;处于2. 92~4. 38 kHz频带内能量的变化量与4. 38~5. 84、7. 3~8. 76 kHz能量的变化量之和基本相等,且呈现相反的变化趋势;当构造煤体所受应力增加时,4. 38~5. 84与7. 3~8. 76 kHz分别为能量增加与减少幅度最大的频带;可以将2. 92~4. 38、4. 38~5. 84 k Hz作为研究构造煤体在瓦斯环境中受载破坏的特征频带。

In order to analyze gas’ s influence on AE band energy during coal rupture under loading,with structural coal as research object,uni-axial compression test was carried out by using self-developed gascontaining coal test device. Then,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 pressure. The results show that the greater gas pressure is,the larger main frequency of AE signal is,the narrower frequency band is,and spectrum transforms gradually from a complex multi-peak form to a single peak form. When three is gas,with the increase of loading stress,frequency band enriches and spectrum shifts to left gradually. As gas pressure changes,energy of 2. 92-4. 38 k Hz,4. 38-5. 84 and 7. 3-8. 76 k Hz changes significantly while that in 2. 92-4. 38 kHz is basically same as the sum of 4. 38-5. 84 and7. 3-8. 76 kHz,showing an opposite trend. When stress of structural coal increases,4. 38-5. 84 and 7. 3-8. 76 kHz indicate the largest increase and decrease of energy respectively. 2. 92-4. 38 kHz and 4. 38-5. 84 k Hz can be used as characteristic frequency bands to study damage of structural coal under loading in mines with gas.