Abstract: The stability of tunnel anchorage is a crucial factor in ensuring the safe operation of suspension bridges, as it forms an integral component of the structure. To investigate the load response behavior of tunnel anchorage in fractured rock interlayers of long-span suspension bridges, we have developed a three-dimensional numerical model. This model allows for a comprehensive evaluation of the stability of the tunnel anchorage, demonstrating its suitability and safety within fractured rock interlayers. Our findings highlight the significant impact of fractured rock interlayers on the deformation of tunnel anchorage. Specifically, the displacement distribution curve of the rear anchor face and surrounding rock exhibits a distinct hump shape, with greater displacement on the left while smaller displacement on the right. Additionally, the interface friction resistance of the anchorage experiences abrupt changes within the fractured rock interlayer region. The failure of the anchorage-rock system commences from the vault area within the fractured rock interlayer, gradually propagating towards the arch waist and bottom until the plastic zone of the anchorage-rock interface is connected. Shear failure in the contact zone between anchorage and rock characterizes the failure mode. The bearing capacity of the tunnel anchorage is governed by the tensile failure of the steel bundles, with the comprehensive ultimate bearing capacity reaching 2.3 times the designed main cable force. Overall, the tunnel anchorage demonstrates favorable stability and applicability within fractured rock interlayers.

Key words: tunnel anchorage, fractured rock mass, large-span suspension bridge, stability analysis, numerical simulation