An upper bound design method for roof bolting support in roadways with top coal

The roadways with top coal are a common type of roadways in thick coal seam mining. After excavation of such roadways, the top-coal rock mass is often loose and broken, and the roof deformation and failure are serious. Thus, the stability control of such roadways is a major concern of engineering design and construction personnel. In this paper, we take the typical roadways with top coal in Zhaolou coal mine of China’s Juye mining area as an example and propose a composite failure mechanism for roadway roof supported by rock bolting. The roof stratification and nonlinear failure characteristics of rock masses are incorporated in it. Then, a simplified design method of roof bolting support is proposed on the basis of the upper bound theorem. Furthermore, this paper shows the influence laws of varying parameters on the required supporting force of roof bolts and provides several practical recommendations for engineering applications. In addition, the effectiveness of the proposed method in this paper is further verified through a specific case analysis on a site typical roadway. The research work in this paper can provide theoretical guidance for support design and construction in roadways with top coal.