Time-frequency evolution of electromagnetic radiation in deformation and fracture of composite coal-rock under different loading rates

To better understand how electromagnetic radiation changes in time domain and frequency domain in loaded composite coal-rocks at various loading rates. A mathematical model of stress-electromagnetic radiation coupling was developed based on the theory of continuous damage mechanics and the Weibull distribution law. This model was examined and validated by uniaxial loading experiments. The findings demonstrate that the change in capacitance between the walls of the oscillating cracks in the coal-rock mass is the primary source of the electromagnetic radiation of the load fracture of the composite coal mass. The loading rate and stress have a positive correlation with the electromagnetic radiation signal intensity, and the evolution law of electromagnetic radiation varies depending on the stress stage. In coal-rock, electromagnetic radiation has a characteristic frequency range of 15-20 kHz. The evolution characteristics in this range are superior, and the precursor phenomena of coal-rock rupture are more significant. This study has significant theoretical implications for understanding the time-frequency evolution law of electromagnetic radiation from coal-rock rupture, investigating the mechanism of electromagnetic radiation generation, and enhancing the monitoring and early warning impact of electromagnetic radiation from coal-rock dynamic disasters. It is anticipated that it will also offer theoretical backing for the evaluation of coal-rock bodies' stability and the electro-seismic coupling monitoring of coal-rock dynamic disasters.