Three-dimension numerical analysis of large-span bridges’ pile foundation adjacent to an existing tunnel

In the process of urban transportation construction, it is inevitable that the new bridges will be adjacent to the existing tunnels. According to the spatial relationship between the new bridge and the existing tunnel, a three-dimension finite differential model of the pile-tunnel interaction is established by a numerical simulation method. The influence of the upper load of the new bridge on the adjacent tunnel is simulated, with the results of the numerical simulation method and the Boussinesq method are compared. It is found that the results of numerical simulation are verified by the Boussinesq method, with the deviation less than 10%. Moreover, the horizontal deformation of the tunnel is central-symmetrically distributed, and the symmetrical point of the horizontal deformation and the position of maximum vertical deformation are both near the midpoint of the two cushion caps. Besides, the deformation of the tunnel is mainly vertical. Last but not least, the influence of the construction and operation of the pile foundation of the bridge on the rails in the existing tunnel meets the control criteria. Therefore, the methods of analysis and parameters in this paper can provide a reference for similar projects.