Study on the Stability of Adjoining Rock of Lower Roadway in Close Distance Coal Seam Mining

Abstract

To address the issue of mutual disturbance between coal seams in close‐proximity coal seam mining, this study examines the opposite excavation of the 10,205 working face and the 20,203 mining roadway in the Longhua Coal Mine. By combining theoretical analysis and numerical simulation, we investigate the mechanical model of stress distribution on the upper working face floor and the changes in the surrounding rock stress environment of the lower coal seam roadway during relative excavation of close‐proximity coal seams. The results indicate that the interlayer distance and stagger distance between the upper and lower coal seams are the primary factors influencing the stress on the surrounding rock of the lower coal seam under opposite operation conditions. The stress environment of the lower coal seam roadway changes mainly with the advancement of the upper coal seam, dividing the roadway into four distinct stress zones: (1) Interlayer rock mass deformation stability zone, (2) mining dynamic pressure influence zone, (3) interlayer rock mass deformation deceleration zone, and (4) small deformation zone of interlayer rock mass. Through numerical modeling and engineering measurements, the surrounding rock stress environment of the 20,203 mining roadway in the Longhua Coal Mine is analyzed. The findings reveal that, under the actual engineering conditions of the Longhua Coal Mine, the staggered distance of the upper working face ranges from 92.6 to 66.3 m, corresponding to the original rock stress stage. The range from 66.3 to 31.3 m represents the mining dynamic pressure influence area, while the range from 31.3 to −17.8 m corresponds to the goaf dynamic pressure influence area. The pressure unloading zone is located between −17.8 and −83.8 m in the upper working face.