## 1 Introduction  
A suspension bridge is a type of large-span bridge that has significant advantages in terms of material performance and the height to span ratio of stiffening beams [1]. At the same time, it has minimal environmental disturbance and can reduce the construction of large-scale foundation projects. It is currently one of the main forms of large-span bridges, with a unique structure and beautiful appearance. The anchoring methods of suspension bridges can be divided into self-anchoring and ground-anchoring. Self-anchored suspension bridges anchor the main cable on both sides of the stiffening beam, resulting in significant axial pressure on the bridge, which is not suitable for large-span bridges [2]. Ground-anchored suspension bridges transmit the main cable force to the ground through anchorages, which are supported by anchorages or surrounding rocks. There is almost no axial force inside the beam, which will not cause instability of the stiffening beam. Therefore, ground-anchored suspension bridges can achieve larger spans and are mostly used for large-span bridges. Ground-anchored anchorages are mainly divided into gravity type and tunnel type according to their mechanism of action. Tunnel anchoring is achieved by setting up inverted wedge-shaped anchorages with wide bottom and narrow top, utilizing the surrounding rock within a certain range of the plug to jointly exert bearing capacity. Compared with gravity type anchorages, tunnel anchorages have smaller engineering quantities, flexible arrangements, and are more economical. Tunnel anchorage demonstrates superior performance over traditional gravity/rock anchorage systems in terms of mechanical efficiency, geological adaptability, and construction economy, particularly for suspension bridge projects in deep overburden and hard rock strata. Future research should focus on its long-term performance under extreme loads (e.g., seismic events and vessel collisions) and the development of intelligent construction technologies to expand its application scope. Based on the many advantages of tunnel anchoring, there have been many successful application cases in bridge engineering, but there are still shortcomings in research on bearing mechanism, failure mode, and anchoring potential excavation, which restricts its further promotion and application in bridge engineering construction [3; 4; 5]. The tunnel anchor, as the main load-bearing part of the suspension bridge's main cable, effectively improves the overall stability of the suspension bridge's main tower and bridge due to its load-bearing characteristics [6]. Therefore, fully considering the bearing capacity and bearing method of tunnel anchors in special geological formations, clarifying the stability, deformation mechanism, and failure mode of tunnel anchor structures and surrounding rocks under load, can effectively clarify the practical application value and promotion significance of tunnel anchors [7]. The concept of tunnel anchor design was first proposed 1932 and the construction example was the Washington Bridge built with basalt rock as the surrounding rock, and the second suspension bridge using tunnel anchor was built in the San Francisco Bay Area four years later [8; 9; 10]. Subsequently, the United Kingdom, as the second country to apply tunnel anchor technology to suspension bridges, built the Forth Road Bridge with coarse basalt as the anchor rock in 1964 [11]. Japan was the first country in Asia to adopt tunnel anchors and built Shimotsui Seto Bridge in diorite and granite surrounding rock mass [12]. At present, tunnel anchors of suspension bridges can be divided into self-anchored and ground-anchored according to the main cable anchoring forms.