Analysis of Construction Impact of a Large Diameter Shield Tunneling Side-Crossing Viaduct Pile Foundations in Short Distance

The construction of shield tunneling through pile foundation will cause additional deformation and internal force of pile foundation, which will affect the safety and applicability of superstructure. Based on the engineering background of a large-diameter shield (\(\Phi\)10.9 m) side crossing a viaduct, a three-dimensional finite element model for the construction of large-diameter shield side crossing viaduct pile foundations is established by using the finite element method. The reliability of the numerical model is verified by using the surface subsidence calculated by Peck formula as a reference. Based on this, the viaduct pier and piles additional response during the construction are developed, the analysis results shows that: Because the pile foot of the viaduct is located below the tunnel, the pier deformation during the shield construction is mainly in the transverse direction along the bridge; The deformation of piles is mainly lateral and vertical, and the lateral deformation is S-shaped, the deformation of piles near the tunnel axis is far away from the tunnel side, and the piles at this position has the maximum lateral deformation; The variation characteristics of the additional internal force of piles are similar to the additional deformation, the position of the maximum additional bending moment is consistent with the position of the maximum lateral deformation, while the maximum additional shear force of pile foundation is slightly lower than the tunnel axis. And the protection measures of elevated pile foundation proposed by the project are demonstrated, The calculation results show that the additional deformation of pier and piles has been significantly improved after taking the measures of stratum reinforcement, and its value is far lower than the standard control value.