Theory and Field to Determine the Construction of Bridge and Tunnel Linked Segment

Bridge–tunnel linked sections characterized by ultra‐small clear distances and steep slopes pose significant construction risks due to strong spatial constraints and complex mechanical interactions between adjacent underground structures. In such conditions, excavation method selection becomes a critical factor governing construction safety and deformation control. Taking the Yuxi‐side tunnel group of the Lvzhijiang Bridge as a case study, this study establishes a three‐dimensional numerical model and integrates it with field monitoring data to systematically compare three excavation methods: full‐face excavation, bench cut, and side heading with pilot tunnels. The schemes are compared using key comparison metrics for scheme selection, including crown displacement evolution, surrounding‐rock plastic‐zone development, and construction safety implications. These results indicate that, although differences in plastic‐zone extent among methods are moderate, the side heading method with pilot tunnels exhibits superior deformation control and more stable excavation responses under ultra‐small clear‐distance conditions. Field monitoring further validates the numerical trends and highlights the influence of site‐specific factors such as potential sliding surfaces and rainfall. These results support a scheme‐selection logic that prioritizes deformation controllability over excavation efficiency in ultra‐small clear‐distance portal zones, and indicate that the side heading method with pilot tunnels is a safer option under the investigated site constraints.