Structural Monitoring Techniques for the Largest Excavation Section Subsea Tunnel: Xiamen Xiang’an Subsea Tunnel

Because of the particular and complex engineering environment of subsea tunnels, effective monitoring techniques should be adopted to ensure the operation security of subsea tunnels. Also, monitoring the condition of steel corrosion in reinforced concrete (RC) of subsea tunnels is especially imperative for ensuring structural serviceability and durability of RC structures. In this paper, monitoring the largest excavation section subsea tunnel, Xiamen Xiang’an Subsea Tunnel, is studied. It includes the layout of monitoring sections and monitoring contents, selection of monitoring locations, and the monitoring instruments. The design of corrosion monitoring system is especially focused on because of its complexity. Both commercial corrosion sensors and developed corrosion sensors based on electrochemical and fiber Bragg grating techniques, respectively, are adopted. The arrangement of corrosion monitoring section and locations as well as the installations of sensors and the establishment of corrosion database are discussed. Finally, the evaluation of corrosion in the subsea tunnel is established based on the monitoring data of reinforced concrete collected in the field. Based on the monitoring data of the subsea tunnel collected in the field, the status of stress and corrosion in the Xiamen Xiang’an Subsea Tunnel can be evaluated.