Failure mechanism of joint-separated granite reinforced by three-dimensional printed bolt

Abstract

This technical note uses bolt-reinforced jointed granite to investigate the relationship between the joint angle and the reinforcing effects of bolt. 3D-printed (3DP) bolts were manufactured with a real bolt as the model prototype, the dimensions and surface geometries were scaled up, and the mechanical properties were similar to those of the prototype bolt. The cylindrical granite specimens were prepared with each separated by a through-going inclined joint plane, the bolt and the granite were combined via bonding agent and nuts. The bearing capacity of the system, the loading status of the bolt, and the displacement/strain changing patterns on the surface of the granite were comprehensively investigated. The results indicated that granite tended to crack when the joint angle was small and that a higher joint angle weakened the bearing capacity of the system, even with the reinforcement of the bolt. For specimens with joint angles of 45° and 60°, a shearing tendency and strain concentration zones nearby the joint plane were clearly observed. This study provide a new methodology for studying the anti-shearing behaviour of bolt in fractured hard rock.