Experimental study on dynamic behavior analysis of coal and its acoustic emission response characteristics under impact failure

Abstract In coal mines, dynamic disasters such as rock bursts seriously threaten the safety of mining activities. Exploring the dynamic behaviors and disaster characteristics in the impact failure process of coal serves as the basis and prerequisite for monitoring and warning rock bursts. In this context, impact failure tests of coal were carried out under different axial static loads and impact velocities to analyze the dynamic behaviors and acoustic emission (AE) response characteristics of coal. The results show that the dynamic behaviors of coal under combined dynamic and static loads are significantly different from those under static loads, and the stress‐strain curve displays double peaks without an obvious compaction stage. As the axial static load grows, the dynamic strength and peak strain both have a quadratic function with the axial static load. When the coal damage intensifies instantaneously, the AE count and energy parameters both witness pulse‐like increases and reach their peak values. The damage effect of axial static loads on coal, though limited, has an extreme point. In contrast, the impact velocity can strengthen the response of AE signals and has linear function relationships with the peak values of AE count and energy. This plays a leading role in the damage to samples and sets a critical point for coal failure and fracture. Compared with the analysis results of stress and strain, the responses of AE signals are more accurate and reliable. Based on AE response characteristics, the damage evolution process of coal under the combined dynamic and static loads can be identified more accurately to reveal the moment corresponding to coal damage and the characteristics of coal failure. The research results are conducive to the further application of AE monitoring methods to early warning of rock burst disasters in coal mining sites.