Three-dimensional pressure-relief prevention and control technology and its application in deep gob-side entry

In response to the challenges posed by significant deformation and maintenance difficulties in the surrounding rock of deep gob-side entries. This study focuses on the 7312 head entry as the research background. The deformation and failure characteristics of the surrounding rock in deep gob-side entries and their underlying causes were analyzed through a combination of field research, theoretical analysis, numerical simulations, and engineering practices. By employing the Mohr stress circle model, the stress distribution and evolution process of the surrounding rock in a deep gob-side entry during the service period were examined. The primary factors contributing to the deformation and failure of the surrounding rock in deep gob-side entries were identified. Furthermore, the principle of three-dimensional pressure relief and prevention in deep gob-side entries was elucidated and its effectiveness was validated. A three-dimensional pressure relief and prevention technology system for deep gob-side entries, with as the core, was proposed. The study findings suggest that: ① Key factors leading to the deformation and failure of the surrounding rock in deep gob-side entries encompass high static loads, mining-induced stresses, rotation of rock block B, support strength for the roadway, mechanical properties of the surrounding rock, and the efficacy of rock pressure relief. ② The optimal timing for implementing the three-dimensional stress relief and control system in deep gob-side entries should be after supporting the gob-side entry or during phases unaffected by mining activities. The implementation targets include rock block B, the hard roof above the solid coal, and stress-concentrated areas in the solid coal. ③ Field engineering applications have demonstrated that the three-dimensional pressure relief and prevention technology system for deep gob-side entries can mitigate stress transmission between rock block B and gob-side entry, reduce the impact of mining stress, transfer concentrated stress from the surrounding rock.