Abstract: This study aims to establish a criterion of acoustic emission (AE) and charge signal for different failure forms of coal at various loading rates. Physical experiments were conducted on coal from a work-face of Wulong mine, and the AE and charge signals were monitored during the failure process of coal at different loading rates. Then we thoroughly investigated the relationships among AE-charge signals and mechanical properties, cracking, energy release at various loading rates. The results showed that with higher rates and earlier stress adjustment, uniaxial compressive strength improved, the release of accumulated deformation energy aggravated, failure modes changed from static load-induced instability to similarity-dynamic-load induced instability, more dynamic characteristics were present, and the risk of compressible rock burst of coal increased. At different loading rates, the AE-charge signal variations were consistent with stress mutation, which were further analysed quantitatively. Hence, based on the obtained AE-charge signals, we proposed a criterion for different coal failure modes. In different mines and work-faces, we could forecast or make an early warning to the risk of compressible rock-burst induced by mining, according to the monitored AE-charge signals in combination with variations of the mining pressure field.

Key words: loading rates, failure forms of coal, energy release, AE-Charge composite criterion, rock-burst of coal compressible type