Study of EMR and AE during Coal Fracture under Quasi-static Uniaxial Compression Load

A quasi-static uniaxial compression experiment was designed to simulate creep damage in coal. During the experiment, electromagnetic radiation (EMR) and acoustic emission (AE) signals were synchronously acquired. The energy of EMR and AE signals were subsequently calculated after the background noise from the equipment and the environment were filtered out. We then analyzed the change in signal energy associated with the sample strength, loading time and other factors. The results showed that as the loading time increases, the frequency of the periodic signal in the EMR energy also increases. In addition, the dominant AE signal energy release occurs only in the final stage of sample failure. However, intenuittent AE pulse clusters were recorded during the entire loading cycle. The analysis of data provided a strong correlation between the change in the AE signal energy and the expansion of micro-cracks in the materials, which is manifested as an irreversible deformation of the material at the macroscopic scale.