Fluid-solid coupling response of shield tunnel lining structure under high water pressure

When a river-crossing shield tunnel is excavated in water-rich soft clay strata, the mechanical properties of the segment lining structure are significantly affected by the water pressure and fluid-solid coupling, especially when the water level changes under the effect of tides. In this study, based on the modified conventional method, the mechanics and deformation characteristics of a lining structure under different high water pressures and fluid-soil coupling effects were analyzed by a finite difference method. The results show that when the water level increases, the axial force of each part of the lining structure increases and the bending moment decreases gradually. The lining structure of underwater tunnel presents a transverse duck-egg deformation with vertical shrinkage and transverse expansion under fluid-solid coupling action. Due to large bending moment, small axial force, and large displacement at the vault and arch bottom of the lining structure, the segment concrete in these parts cracks easily and the joints are prone to warping. Considering fluid-solid coupling effect when an underwater shield tunnel passes through high water pressure strata, the axial force of the segment lining structure is large and the bending moment is small, which makes the stress of the lining structure more reasonable.