Cyclic fatigue characteristics of strong burst-prone coal: experimental insights from energy dissipation, hysteresis and micro-seismicity

Abstract This paper documents investigations of the fatigue behaviour of strong burst-prone coal in terms of energy dissipation, hysteresis and micro-seismicity. The energy dissipation characteristics of the coal subjected to multi-level-frequency cyclic loading were studied. Two hysteresis indexes were proposed according to the stress-strain relation during cyclic loading. These two indexes are effective as twin precursors to predict the fatigue failure of coal samples. The effect of frequency on energy dissipation rate was studied. With the aid of an AE monitoring system and a high speed camera, 3D distribution of AE events and failure patterns were obtained. The damage evolution of coal samples subjected to cyclic loading is not homogenous due to the stiffness effect of the loading platen. The failure patterns captured by high speed camera are consistent with the results characterized by the spatial distribution of the AE events.