The role of stress in controlling infrared radiation during coal and rock failures

Abstract

AbstractDuring coal failure under loading, variations in infrared radiation (IR) characteristics can be observed in response to stress drops. To explore the quantitative relation between the stress and IR characteristics, a new quantitative failure indicator called the variance of successive minus infrared image temperature (VSMIT) has been developed to study IR characteristics during the uniaxial compression loading. Results from this study indicate that the role of stress in controlling IR characteristics of the coal sample is universal during loading with the ratio of 90.2%. In addition, the role of stress in controlling IR is significant, given that the average sudden change coefficient of VSMIT is at least three orders of magnitudes of the stress drop coefficient of the coal sample. Moreover, the control effect has predictability (precursor). Before failure and instability, simultaneous sudden changes of VSMIT and stress can be observed in 76.2% of coal samples, which can thus be regarded as the IR precursor of coal failure. The present work can provide a new method and some novel indexes for monitoring stress state as well as fracture development in coal rocks, which will also be of theoretical guidance for promoting the applications of IR‐based forecasting and early warning of some natural and rock engineering disasters mainly including rockbursts and coalbursts induced by the fractures in the coal rock.