An exploration of improving stability of gob-side entry retained with graded and zoned pressure relief technology: a case study.

To address the issues of uncertain pressure relief effectiveness and poor control of surrounding rock caused by the composite nature of the roof strata in the gob-side entry retained (GER), as well as significant changes in strata's thickness and stability differences, this study focuses on the airway of the panel 3113 N in Longtan Coal Mine. Through field detection, theoretical analysis, and on-site applications, a stable mechanical model of the hard roof strata is established, elucidating the factors influencing fracture and instability in composite roof strata. The results indicate that roof stability of the GER depends on the position and ultimate load-bearing capacity of the hard roof strata, which in turn affects roof pressure relief effectiveness.