Calculation Method of Longitudinal Deformation of Metro Shield Tunnel Based on Symplectic Elasticity Theory

Aiming at the longitudinal non-uniform deformation and stress issues of shield tunnels under adjacent construction conditions, the shield tunnel is simplified as a Timoshenko beam, and the surrounding soil layer is simplified as a Pasternak elastic foundation. By fully considering the interaction between the tunnel and soil, and integrating Symplectic elasticity theory and finite element method, a new longitudinal deformation calculation model for shield tunnels is established. The proposed model can reflect the shear behavior of soil, the dislocation deformation of the tunnel ring seam, and the bending deformation of the segment ring. Besides, it can also evaluate the longitudinal deformation and internal force response of shield tunnel under adjacent construction disturbance, and it is easy to program. By comparing with the existing numerical simulation and field case, the reliability of the model’s calculation results is verified. Finally, taking the load condition as an example, the influence of the tunnel axial depth, load range, and load eccentricity on the tunnel longitudinal deformation is discussed in detail by using this new method. This provides a theoretical basis for the tunnel structural safety evaluation under load.