Research on the distribution law of stress and gas in underlying stress-relief coal seam at close range

Chu Shaofei

doi:10.19896/j.cnki.mtkj.2025.05.022

Abstract：In order to effectively control the gas emission in underlying stress-relief coal seam at close range,a coupled model of diffu-sion,seepage and deformation of coal dual pore media was established.The stress and multi factor coupling gas outburst law of underly-ing stress-relief layer induced by the first coal seam mining were analyzed,and the influence mechanism of the original stress,original gas pressure and initial permeability on the gas pressure change in the stress-relief layer was further explored.The results show that the stress field redistributed after the first mining layer is symmetrically distributed in the middle of working face.The closer the area is to the roof and floor of working face,the greater the degree of stress relief,and stress concentration occurs at both ends of working face,re-sulting in a significant increase in permeability value of damaged coal body.Gas pressure in stress-relief layer decreases,and the de-crease in gas pressure in most areas is similar.Along the parallel direction of working face,gas pressure change curve shows a"W"shape distribution.The gas pressure shows a pattern of first decreasing and then increasing from both ends to the middle of working face;gas pressure in the stress-relief layer at about 10 meters from both ends of working face has the largest decrease(approximately 9％).The original stress,original gas pressure,and initial permeability are all positively correlated with the decrease in gas pressure of stress-relief layer.The influence of initial permeability on gas pressure changes is higher than that of original stress and original gas pressure.Research results can provide reference for efficient gas extraction in underlying close range stress-relief coal seams,in order to reduce gas emission and ensure coal mine safety production.