Perpustakaan Digital ITB

Coal burst is a dynamic failure phenomenon that is caused by a sudden release of strain energy during mining. It is extremely difficult to predict coal burst accurately. In this study, experimental tests were performed under uniaxial cyclic load-unload conditions using a microcomputer-controlled electrohydraulic servo stiffness compressor with acoustic emission (AE) monitoring. The experiments data, such as the AE energy, AE energy ratio and load-unload energy response ratio, were obtained. The Y value of the load-unload response ratio (LURR) was calculated based on these data. The results show that variation characteristics of the AE energy release can be related to the failure of coal specimens. The concentrated release of AE energy occurs at the beginning of the plastic deformation stage. Then, AE energy was accumulated before coal specimens' failure. The variation characteristics of the LURR (Y1) and Benioff strain (Y2) were obtained. The fluctuation of Y1 and Y2 values was exhibited to coincide with the AE energy accumulation, which allowed predicting coal failures. The predicting time point where the Y1 and Y2 values were both close to 1 could be defined as the predicting key point of coal specimens' failure. These results of experimental investigation show a meaningful attempt for predicting coal failure.