Study on temperature evolution law of coal containing gas under uniaxial loading process with different loading rates

Abstract

In order to investigate the evolution law of coal temperature during the gestation process of coal and gas outburst, laboratory experiments and numerical simulation approaches were employed. Infrared thermal radiation experiments on the surface of outburst coal during uniaxial loading and failure of coal were conducted. A coal and gas thermal-hydromechanical coupling model considering the endothermic effect of desorption was established. Numerical simulation of uniaxial loading of gas-containing coal was implemented to study the influences of deformation energy, frictional heat, and adsorption/desorption endothermic effects on coal temperature. The results indicate that the temperature of coal samples during the uniaxial loading and failure process generally exhibits a stepwise temperature increase. In the initial stage, the elastic thermal effect leads to a slow and fluctuating rise in the temperature of coal samples. During the yield and plastic deformation stages, frictional heat causes a rapid increase in the temperature of coal samples. With the increase of the loading rate, the increment of the temperature of coal samples gradually decreases and reaches the peak when the loading stress is 70% of the peak stress. According to the numerical calculation results, with the increase of the loading rate, the temperature reduction caused by gas desorption relatively decreases. By comparing the experimental results and numerical simulation results, it is found that the temperature reduction caused by desorption is greater than the temperature increments caused by deformation energy and frictional heat. The desorption endothermic effect and frictional heat effect are the dominant factors controlling the temperature variation of coal during the gestation process of outburst. The research achievements have significant theoretical significance and practical value for revealing the temperature evolution mechanism during the gestation process of coal and gas outburst, predicting coal and gas outburst, and protecting the atmospheric environment.