Effect of Mechanical Property on Acoustic Emission Activity of Coal during Failure Process

Based on the method of experimental study, for soft coal with outburst liability, strong impact coal and weak impact coal that has different mechanical properties, the fractal characteristics and time-series parameters including acoustic emission (AE) activity frequency and energy in the course of loading damage were studied, the influence of coal mechanical property on AE activity was also discussed. The results showed that the variation of AE characteristic parameters is related to the damage phase of coal specimen, and the mechanical property of coal has an important influence on time-series evolution of AE activity. During the post-peak deformation phase of coal, AE activity of soft coal with outburst liability shows a gradual downward trend, strong impact coal demonstrates a rapid pulse increase, and weak impact coal shows a "pulse-decrease"alternating declining pattern. The AE fractal evolution of coals with different mechanical properties during failure process has the same variation trend that "first rise, then fall". It reflects that the failure process of coal is a crack propagation activity process from dispersed and disorderly cracking to localized and ordered fracture. The comprehensive precursory information that combined with AE time-series and fractal dimension change can improve the validity and accuracy of the identification model for coal instability disaster.