Infrared radiation characteristics based rock failure indicator index for acidic mudstone under uniaxial loading

In this research, a new rock failure precursor is proposed that can be used effectively for an early rock failure indicator (RFI). This RFI is based on the characteristics of mudstone and due to the acidic coal mining environment; the tests were performed on the acidic samples under uniaxial loading in the presence of infrared radiation (IR). Three IR characteristics indexes, i.e., variance of infrared radiation temperature (VIRT), average infrared radiation temperature (AIRT), and variance of differential infrared image temperature (VDIIT), were used for predicting rock failure precursors. The effects of acidity on these indexes were also evaluated, and the results indicate that the aforementioned indexes give failure precursors nearly at the failure point of the samples. Thus, for an early rock failure precursor, the absolute rate of ratio (ratio of AIRT and VDIIT) was used for the first time in the research. This ratio gives the average time of 78 s before the failure compared to 52 s of AIRT and VDIIT. The precursor point stresses in the absolute rate of ratio is lower (0.87 σ peak ) compared to AIRT and VDIIT (0.94 σ peak ). It is revealed from the results that the absolute rate of ratio gives 26 s an early RFI than VIRT and VDIIT. Hence, the new index is proposed to be used as an early indicator of rock failure in an acidic environment for the safe and efficient execution of underground projects.