Structural Design Method for Narrow Coal Pillars in Gateway Protection: Framework and Field Case Study

Coal pillars are important safety structures for maintaining the stability of underground coal mine roadways. To address both coal resource loss from wide pillars and the need for safer, more sustainable underground building structures, this study proposes a framework for controlling the surrounding rock based on the narrow pillar. By establishing a load-bearing mechanical model for narrow coal pillars and a mechanical model for roof instability, the design principles of key parameters were clarified, including the optimal width, the required support strength for the pillar–roof system, and the height and angle of roof pre-splitting. In addition, zoning control measures and corresponding technical procedures for adjacent mining roadways were proposed. This technology was applied in Tashan Mine and, during the extraction of panel 8311, the surrounding rock stability of roadway 2312 was well maintained, with the maximum deformation of the solid coal rib measured at 135 mm, while that of the narrow pillar reached 386 mm. The proposed design method can effectively improve coal recovery in underground mining and provide theoretical and technical guidance for coal pillar stability control and wide pillar optimization under complex mining conditions.