• Energy Research

ABSTRACTThe multi‐field coupling relationship and temperature evolution mechanism of gas‐containing coal in areas affected by geological structures were investigated, focusing specifically on the engineering aspects of a reverse fault in the No. 3 coal seam at the Xinjing Coal Mine. An analysis was conducted to examine the thermal‐fluid‐solid coupling behavior of gas‐containing coal. A thermal‐fluid‐solid coupling model for gas‐containing coal, accounting for the effects of damage, was developed to simulate the incubation process of coal and gas outbursts within the fault zone during the advancement of the working face. The study has indicated that faults not only degrade the mechanical properties of the surrounding coal‐rock mass, but also disrupt the continuity of coal seam stress. Gas tends to accumulate near fault zones, resulting in differences in the gas pressure and content on either side of the fault, thereby substantially increasing the likelihood of coal and gas outbursts. The primary factors influencing temperature variations include deformation energy, energy from gas expansion, thermal convection, thermal conduction, and the thermal effects associated with adsorption and desorption. Among these factors, the endothermic effect associated with adsorption and desorption significantly influences the temperature fluctuations in coal. The results of this study provide a theoretical foundation for exploring the mechanisms underlying coal and gas outbursts, improving the interdisciplinary coupling theory for coal and gas systems and employing temperature metrics to predict such outbursts.

AbstractWith the shift of coal resources to deep mining, the occurrence of long‐distance coal seams has increased, and protective layer mining is facing new challenges. This paper attempts to explain the stress evolution law of the upper coal group in the long‐distance mining of the lower coal group in Pingdingshan No. 8 Coal Mine. A simulation model of advance mining of lower‐group coal long‐distance was established. The stress evolution law of the upper coal seam under the influence of advanced mining disturbance of the lower coal seam is studied. The following conclusions were obtained: The advance mining of the lower coal group had a positive or negative impact on the stress distribution of the upper coal seam group. With the recovery of the lower coal group of the F‐21030 working face, the overburden of the F‐21030 goaf finally formed a “Y” type pressure relief area. The pressure relief effect of the E‐21070 working face near the stopping line was obvious. The coal seam of Group E was divided into three areas affected by the advance mining of the lower coal seam. The maximum pressure relief value was 6.6% lower than the initial stress. According to the simulation results, the E‐21070 working face was divided into three regions, namely, the pressure relief region, the stress increase region, and the original stress region. According to the field drainage results of pressure relief gas, the extraction curve could be divided into three parts, namely, the stable area, pressure relief area, and stress recovery area. The maximum pure gas drainage volume could reach seven to eight times of the original area. The pressure relief extraction effect was remarkable, and the optimal extraction range was 22–210 m behind the coal face of the group.