Field and numerical investigation on the stability of coal pillars of gob-side entry driving with top coal

Determining the reasonable width of coal pillars is the key to the successful application of gob-side entry driving technology in coal mining. A comprehensive research method including numerical simulation, field monitoring, and theoretical analysis was proposed to determine the reasonable width of the coal pillars of gob-side entry with top coal based on a case study conducted in the Lugou Coal Mine, Henan Province, China. According to a comprehensive analysis of the stress distribution characteristics of the narrow coal pillar and the influence of the coal pillar width on the roadway deformation, the reasonable width of the coal pillar was determined to be 6 m with consideration of the stability of the coal pillar, roadway deformation, and coal recovery rate. Two principles for maintaining the stability of the gob-side entry with top coal were proposed, that is, strengthening the roof support to ensure top coal stability, and strengthening the support structure of the coal ribs to achieve collaborative control. Field monitoring indicated that the bolting support could effectively control the severe deformation of the roadway along the gob-side entry driving in the soft coal seam.