Study on the stress distribution characteristics and gas permeability influence of reasonable width of isolated coal pillars

A mechanical model of the stress distribution of the protective coal pillar was constructed to explore the reasonable width of a protective coal pillar in an isolated working face and further reduce the impact of hazardous gases on the mining face, taking the mining of the isolated working face under the goaf as the engineering context. The width of the protective coal pillar was positively correlated with the height of the key layer and the stress of the accessories and negatively correlated with the ultimate bearing strength and caving angle of the coal pillar. The stress distribution of the surrounding rock under different coal pillar widths is analyzed by a numerical model. Field tests revealed that the deformation of the surrounding rock was effectively controlled when the width of the protective coal pillar was 23 m. The proportion of the elastic core area inside the coal pillar is 46.8%, and the overflow of hazardous gas is essentially zero within 30 days. This research provides a reference for the retention of protective coal pillars and the control of hazardous gas under similar engineering geological conditions.