Section Design of Mining Roadway in "Three Soft" Coal Seam Based on Complex Function Method

Aiming at the difficulties of mining roadway maintenance and substituting shed in "three soft" coal seam, the flattened U shape roadway section design was proposed according to the condition of 3204 working face in Zouzhuang Coal Mine. The analytical expression of surrounding rock stress in roadway with arbitrary section was obtained by utilizing the complex function method; the surrounding rock stress distribution maps of rectangular, trapezoidal and flattened U shape section roadway were given. The laws of stress distribution showed that the surrounding rock stress of flattened U shape roadway was smaller than those of rectangular and trapezoidal roadway, and flattened U shape roadway was more suitable for "three soft" coal seam. Field measurement showed that the maximum convergence of roadway sides and roof-to-floor were 312 mm and 267 mm respectively. The deformation of roadway surrounding rock has been effectively controlled with the application of flattened U shape roadway section design.