## 1 Introduction  
The shield tunnel construction method has been well applied and developed in urban rail and the construction and development of urban rail transit because of its high safety, high degree of mechanization, and little impact on ground traffic [1, 2]. However, excavation of a shield tunnel causes stratum loss. If the tunnel is close to existing buildings and structures such as bridge piles, it can lead to the deformation of existing bridge piles and harm the safety of existing bridges [3, 4, 5]. Due to the large excavation area, extensive construction disturbance range, and strength of the large-diameter shield, the work has a significant and adverse impact on existing bridge piles [6]. Therefore, research on the stress and deformation of deep foundations (e.g., piles) caused by tunnel excavation is a relevant and exciting topic in subway construction.  
At present, research on shield crossing bridge piles mainly adopts the methods of theoretical analysis [7, 8], model testing [9], numerical simulation [10, 11], and field monitoring [12, 13]. [PERSON] et al. [7] studied tunnel side piles related to fluid-structure coupling. The results showed that the groundwater on both sides of the surface presents a \"U\" flow trend to the upper part of the tunnel, vertical displacement of the pile results in settlement of the upper pile and upward deformation of the lower pile, and horizontal displacement of the pile presents a continuous \"S\" distribution. [PERSON] et al. [12] showed that the expansion and reinforcement of the raft foundation of Fengqi Bridge and the improvement of the composite ground effectively reduced bridge settlement during tunnelling and improvedthe mechanical conditions of the bridge structure. [PERSON] et al. [14] studied the response of different minimum distances between pile groups and tunnel centerlines in clay using physical scale model tests and three-dimensional nonlinear finite element models. [PERSON] et al. [15] established a three-dimensional finite element model of pile foundation construction of a large-diameter shield side crossing viaduct using the finite element method, developed an additional response of viaduct pier and pile during construction, and demonstrated the protection measures of viaduct pile foundation involved in the project. The above research mainly focused on the problem of conventional diameter shield crossing through buildings and structures. There is little research on large-diameter (especially 16 m-level) slurry shield tunnel construction on the surrounding soil and structure.  
Due to the large diameter of the slurry shield studied in this paper, the tunnel disturbance to the surrounding soil and structure was the main problem during design and construction, especially with respect to the two bridge piles of Hongling Interchange No. 1 Bridge. Prior experience with this type of slurry shield tunnelling project is relatively limited. Our research considered a 15.8 m large-diameter shield machine made in China to excavate the Chunfeng tunnel as the background of the study. First, based on previous engineering experience, reinforcement measures of shield crossing of bridge piles was considered. Based on this, PLAXIS 3D finite element software was used to simulate the process of shield tunnelling through the piles of Hongling Interchange No. 1 Bridge, analyze the mechanical characteristics of the piles in the process of shield tunnelling through the bridge piles, and evaluate the reliability of the reinforcement measures. Finally, combined with field monitoring data, the accuracy of the model and the rationality of the treatment measures were verified.