Analysis of reasonable unsupported roof distance for 15301 transport gateway in Zhuangzihe Coal Mine

To address the problem of slow roadway excavation speed caused by a small unsupported roof distance at the heading face, the 15301 transport gateway of Zhuangzihe Coal Mine was taken as the research object. A thin-plate mechanical model was established to calculate the limit unsupported roof distance, and numerical simulation was conducted to analyze surrounding rock stress and failure deformation under different unsupported roof distances, thereby determining the maximum unsupported roof distance. The results show that the limit unsupported roof distance obtained from theoretical calculation is 3.09 m, while the maximum unsupported roof distance obtained from numerical simulation is 3.3 m. By integrating both results and considering a certain safety factor, the maximum reasonable unsupported roof distance for the transport gateway in Zhuangzihe Coal Mine is finally determined to be 2.3 m. After applying the research findings on site, the field-measured mine pressure data indicate that the roadway surrounding rock deformation is small and the rock bolts (cables) are under good stress conditions.