Variation characteristics and homology analysis of loaded coal-rock's non-stress signals

Abstract

When loaded coal-rock is deformed, various non-stress signals, such as temperature-type, electromagnetic-type, and vibration-type, exhibit distinct characteristics as stress'. In order to clarify the relationship between various coal-rock's non-stress signals and establish the corresponding relationship between these characteristics and the damage degree, the study first analysed the generation and evolution mechanisms of the three types of non-stress signals from the perspective of physical mechanisms and energy, and then investigated the changing characteristics of loaded coal-rock's non-stress signals based on uniaxial experiments at different rates. Finally, the homology of non-stress signals is verified by comparing the characteristics of different non-stress signals. The findings indicate that the variation of the non-stress signal is connected to the status of the coal-rock fracture, which is a physical expression of external mechanical energy dissipation. Moreover, the degree of damage inside the coal-rock is proportional to the strength of each non-stress signal source, and the location of the measurement point has no effect on the details associated with coal-rock damage in the non-stress signal. All of the non-stress signals display changing features and fracture precursors connected to the coal-rock damage state. Among the three kinds of non-stress signals, the temperature-type non-stress signal exhibits the most obvious stationarity and stage, whereas the electromagnetic-type and vibration-type signals would fluctuate because of the stress stability. However, they differ greatly in terms of sensitivity to stress variations and difficulties in diagnosing fracture precursors. In addition, the maximum of the vibration-type and electromagnetic-type signals often corresponds with the “plateau” of the temperature-type signal, which means that three different non-stress signal features occur together. Furthermore, the homology of loaded coal-rock's non-stress signals can be efficiently verified by both evidence from theory and experiment. This research can offer a way to determine the loading condition of coal-rock by using non-stress signals, and it can theoretically promote future studies on the prevention of coal and rock dynamic disasters by multi-information fusion.