Abstract:
The 211211 return airway of Tucheng Mine is designed to gob-side entry with small coal pillars. Considering the significant deformation of the 211211 return airway and the need for multiple repairs due to mining-induced effects during working face extraction, the technology of roof cutting by dense drilling is proposed. Through theoretical analysis, the breaking location of the key block B is calculated to be 5.63 m from the edge of the goaf, positioned above the roadway, representing the most adverse condition for roadway surrounding rock stability. Based on theoretical calculations, the technical parameters for roof cutting by dense drilling, including height, angle, and spacing, are determined. Numerical simulation results demonstrate that after roof cutting, the vertical stress peak within the small coal pillars decreased by approximately 20% compared to pre-cutting conditions, and roadway deformation is significantly reduced. Field measurements show that roof cutting by dense drilling substantially reduces the convergence of the roof, floor, and sidewalls; roof and floor convergence decreased to 210 mm, and sidewall convergence decreases to 270 mm. The deformation of the roadway surrounding rock is effectively controlled, improving the stability of the surrounding rock.