自然和饱水煤样巴西劈裂过程声发射幅频特征试验

Experiment of amplitude and frequency feature of acoustic emission during Brazilian splitting testing of natural and saturated coal samples

为研究水对煤样拉伸破裂过程中力学及声发射特性的影响,对自然和饱水煤样进行巴西劈裂试验,利用频谱分析法对声发射波形信息进行研究。试验结果表明:拉伸破裂过程中,饱水煤样主频集中范围小于自然煤样;破坏阶段饱水煤样释放的能量比自然煤样少,其最大主频幅值低于自然煤样;自然煤样声发射信号以低频低幅值、中频低幅值和高频低幅值信号为主,煤样破裂时低频和高频信号有向中频带转移的趋势,饱水煤样声发射信号以低频低幅值信号为主,煤样破裂时低频高幅值和中频低幅值信号增加;低频高幅值信号对应煤样破裂过程中大尺度裂纹产生;饱水煤样破裂时低频高幅值信号数量多于自然煤样,反映了饱水煤样破裂时产生的大尺度裂纹更多。

In order to study influence of water on mechanical and acoustic emission(AE)characteristics of coal samples during tensile and rupture,Brazilian splitting test was carried out on natural and saturated coal samples,and the AE waveform information was studied by spectrum analysis.The test results show that during the tensile and rupture process,distribution range of the saturated coal sample dominant frequency signal is lower than that of the natural coal sample.In destruction stage,the saturated coal sample releases less energy than the natural coal sample,and its maximum amplitude of dominant frequency is lower than the natural coal sample.The natural coal sample AE signal is mainly low-frequency low-amplitude,medium-frequency low-amplitude and high-frequency low-amplitude,and the low-frequency and high-frequency tend to shift to the middle-frequency band when the coal sample ruptures.The saturated coal sample AE signals is mainly low-frequency low-amplitude,and the low-frequency high-amplitude and medium-frequency low-amplitude increase when the coal sample ruptures.The low-frequency high-amplitude signals correspond to the large scale cracks generated during the coal sample rupture.When the saturated coal sample ruptures,the number of low-frequency high-amplitude signals is more than that of natural coal samples,which reflects that the large scale cracks generated during the rupture of the saturated coal sample are more than other cracks.