(1.Safety Engineering College,North China University of Science and Technology,Sanhe ,China; 2.Datong Coal Mine Group Company,Datong ,China

According to the roof support problem of the gateway retained along the goaf with no gateway sidewall backfilling and support in No. 1528 coal mining face of Gequan Mine,the roof fracture position that in theory and numerical simulation and the technology of cutting roof are studied in order to improve roof status. The results show that a mechanical model of the seam interface stress is established based on the law of plastic area stress distribution. The roof fracture position in elastic-plastic intersection is derived. The simulation results show that the maximum shear stress is in 2.4 m, at the same time, the main roof began to plastic failure in 2.4 m. Based on the analysis of influencing factors that main roof fracture position, the coal thickness, mining depth, the mechanical properties of coal interface and stress concentration factor has great influence. In order to cutting roof reasonable, adopted strength combination support to curtting roof and observed the fracture line. It proved that the supporting is effective to form rational overhang length of the roof. The research provides a reference for stable control of surrounding rock of the gob-side entry retaining with no roadside filling support.