1. Supporting surrounding rock

　　The tunnel anchor rod restricts the deformation of the surrounding rock of the Jigongjie tunnel and applies pressure to the surrounding rock, so that the surrounding rock near the surface of the tunnel in a two-dimensional stress state maintains a three-dimensional stress state, thereby preventing the deterioration of the strength of the surrounding rock.

　　2. Reinforce surrounding rock

　　Due to the reinforcement of the system bolts, the surrounding rock, especially the joint cracks and fracture surfaces in the loose zone of the Jigongjie Tunnel, can be connected, thereby increasing the strength of the surrounding rock in the anchoring zone. The loosening zone of the rock mass and surrounding rock is very effective, which helps the fractured rock mass and the loose zone to form a whole and become a "reinforcement zone".

　　3. Increase the friction resistance between layers of the Jigongjie Tunnel to form a "combined beam"

　　For horizontal or gently inclined layered surrounding rock, the tunnel bolt group can connect several layers of rock together and increase the frictional resistance between the layers. From the point of view of structural mechanics, a "combined beam" is formed.

　　4. "Suspended" function

　　The so-called "suspension" function of tunnel bolts refers to the use of bolts to connect individual dangerous rocks to stable surrounding rocks in order to prevent individual dangerous rocks from falling or slipping. This effect is mainly manifested in the reinforcement of partially unstable rock masses.