Fluid-Solid Interaction-Based Mechanical Characteristics of Underwater Shield Tunnel

In order to investigate the mechanical characteristics of a underwater shield tunnel under fluid-solid interaction during construction stage, a numerical simulation model was established to calculate water pressure on segment lining by taking Shiziyang shield tunnel as an example. Field tests were carried out to measure external and internal loads acting on segment lining structure. The calculated water pressure was acted on the spring-beam model to analyze structural internal forces, and mechanical characteristics of a segment structure under fluid-solid interaction during construction stage were obtained. The research result shows that water pressure fluctuates obviously to the first 3 to 5 rings after the target segment ring lefts the shield tail owing to grouting pressure. When the number of left-shield-tail rings comes to 10 or more, the water pressure gets close to hydrostatic pressure with the dissertation of grouting pressure and the vanishing of fluid-solid interaction.