Coal Pillar Stress Weakening Technology and Application by Gob-Side Entry Driving and Hydraulic Roof Cutting in Deep Shafts Mines

To solve the problems of serious deformation and support difficulty of deep and narrow gob-side coal pillars, an optimized hydraulic roof cutting structural model for the roof structure of narrow gob-side coal pillars in kilometer-deep shafts was established based on the 6302 working face of the Xinhe coal mine. The influence of factors such as the angle and height of hydraulic roof cutting on the stress evolution of narrow gob-side coal pillars was analyzed, the principle of the pressure relief of hydraulic roof cutting of narrow gob-side coal pillars in kilometer-deep shafts was revealed, and an industrial application was conducted. The results of the study show that, first, the hydraulic roof cutting of narrow gob-side coal pillars in a kilometer-deep shaft transfers the roof load only to the gob area, but not to the solid-side deep coal body; and second, there is an optimal height for roof cutting and pressure relief, i.e., the effect of roof cutting and pressure relief will not be improved after the second critical layer is exceeded. An industrial application was carried out along the gob-side entry at the 6302 working face of the Xinhe coal mine, which showed that the strength of the roof was weakened, the stress concentration in the coal pillars was relieved, and the deformation of the rocks surrounding the roadway was controlled after hydraulic roof cutting and pressure relief. This study provides some technical guidance for the stability control of gob-side entries under similar conditions.