Deformation characteristics of a roadway in steeply inclined formations and its improved support

Abstract

Mining roadways in steeply inclined rock layers commonly experience severe deformation in form of large asymmetric deformation, roof subsidence and floor heave, which significantly threaten the stability of a roadway. Using a coal exploration roadway in Anhui Province, China as a case study, the deformation characteristics of a roadway in steeply inclined rock formations and the corresponding improved support scheme is analysed by numerical simulation. The simulation is performed using a cohesive element to consider the influence of geologic bedding plane around the roadway. The results show that: due to the spatial relationship of the roadway and the two bedding planes (i.e. interfaces), rocks above the roadway move downward along the interface, while rocks below the roadway move upward along the interface, the maximum deformation occurs along the upper left and lower right sides of the roadway surface, which accounts for the large leaning asymmetric deformation of the roadway (right inclination). An improved support scheme for the roadway is proposed, using long cables to restrain severe deformation, short cables and enclosed U-shaped steel sets to improve the ground stress state. The proposed scheme can effectively restrain floor heave, manage large asymmetrical deformation compared to the original scheme.