Research on the Impact of Large-Diameter Pipe Jacking Side-Passing Construction on Existing Bridge Pile Foundations

In order to explore the disturbance effects of near side-passing of large-diameter pipe jacking on existing pile foundations， the deformation and internal force responses of pile foundations under different construction parameters were analyzed. A numerical model of a curved jacking tunnel crossing the existing pile foundation at a close range was established based by employing a three-dimensional nonlinear finite element method. The reliability of the model was verified through theoretical analysis and field monitoring. The variations in internal forces and deformations of the pile foundation during different stages of the pipe jacking construction were summarized. On this basis， the disturbance effects on the existing bridge piles caused by different parameters， such as clearance， excavation face supporting force， pipe-soil friction. and grouting pressure， were analyzed. The results show that a reduction in clearance significantly enhances the disturbance effects of pipe jacking construction on the pile foundation. The excavation face supporting force has a particularly significant impact on the longitudinal deformation of the pile foundation， and an increase in supporting force amplifies the sensitivity of the pile foundation to other disturbance factors. The anti-resistance effect of thixotropic grout plays an important role in ensuring structural safety. When the anti-drag efficiency of thixotropic grout is maintained and the grouting pressure is within the range of static soil pressure ±50 kPa， the disturbance effect on the pile foundation can be effectively reduced.