Key protection techniques adopted and analysis of influence on adjacent buildings due to the Bund Tunnel construction

• Three strategies were proposed to protect the adjacent historical buildings during the EPBS excavation process.
• A FEM analysis was conducted to analyze the influence on the adjacent building before and after bored piles installation.
• The optimized construction parameters are proposed to reduce the influence induced by EPBS excavation.
• In situ monitoring data were collected and the protective effects were validated with the monitoring data.

The Bund Tunnel is 14.27 m in diameter. It is the first application of super diameter earth pressure balanced shield (EPBS) in China. There are many historical buildings along the construction line, and the minimum horizontal distance from the building to the tunnel side varies from 1.7 m to 30 m. Considering the importance of these historical buildings and the complicated construction processes, it is essential to adopt effective protection techniques to ensure safety during the tunnel construction. Three kinds of protection techniques are presented in this paper. Firstly, underground cut-off wall built by bored piles is used to separate the buildings and tunnel when the minimum horizontal distance from the building to the tunnel side is less than 5 m. Secondly, the grouting reinforcement technique is adopted when the minimum clear distance is between 5 m and 10 m. Finally, if the minimum clear distance is larger than 10 m, the optimized construction parameters are selected to reduce the influence induced by the EPBS excavation. The deformations of some typical buildings are monitored. The results of this project will be a useful reference for similar future projects.