Abstract:

To investigate the mechanical behavior, infrared radiation, and fracture evolution characteristics of coal with different degrees of damage, simultaneous infrared radiation detection tests were carried out during uniaxial compression to analyze the mechanical behavior and infrared radiation response characteristics of different specimens after loading. And then based on the macroscopic mechanical properties of the specimens, particle flow software PFC^2D was used to simulate the uniaxial compression of the specimens to analyze the fracture evolution characteristics of the specimens on a meso-scale. The results show that the degree of damage affects the strength and deformation characteristics of the specimens. With the increase of the degree of damage, the specimens show weak brittleness and strong plasticity characteristics; the specimens with different degrees of damage all show time-varying characteristics of temperature increase; the temperature of Class I and Class II specimens show a precursor of a sudden increase before rupture, with a sudden increase of temperature up to about 1.7 ℃, while Class III specimens show the characteristics of a sudden drop followed by a rapid increase, with a temperature increase of 0.93 ℃. The thermal infrared images show divergent characteristics during the loading process, with the high or low-temperature anomalies corresponding to the spatial location of the damage to the coal rock specimens. The damaged area of the specimens is approximately the same as the anomalous area of the infrared radiation, and there is a close correlation between the internal damage (fracture development) and the surface damage (infrared radiation). The results of the study can provide a reference for the early warning of dynamic hazards during the mining process of coal bodies with different degrees of damage.

Key words: degree of damage, deformation rupture, infrared radiation, fracture evolution