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

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.