## 1 Introduction
[18] systematically studied the brittle failure of buried pipelines caused by ground subsidence and tunnel excavation through a centrifuge tests and numerical simulations. Scholars studied the influence of tunnel construction on the surrounding environment through numerical models [19; 20; 21]. [PERSON] et al. [22] carried out model test and numerical simulation on the construction progress of the Daling tunnel. By monitoring the deformation and stress changes of the surrounding rock in real time, they studied the mechanical response law and revealed the mechanical characteristics of large-span and small-span tunnels during construction. [PERSON] et al. [23] studied the dynamic interaction between the tunnel, soil and buildings on the ground through fully coupled FEM modeling and also studied the influence of the tunnel on soil and building response. The current research mainly focuses on the influence of construction and structural parameters of cofferdams on their own deformation, while relatively little research has been conducted on the influence of tunnel foundation pit construction or on the deformation characteristics of the double-row steel sheet pile cofferdam. [PERSON] et al. [24] used a finite difference model to evaluate the deformation of double-row steel sheet piles in deep foundation pit construction and summarized the rules that influenced the inclination angle, pile diameter, penetration depth, and row spacing of deformation. Finite element software was used to study the mutual influence between deep foundation pits and cofferdams and found that the excavation of foundation pits mainly caused the horizontal deformation on the lower part of the cofferdam pile foundation to increase [25; 26]. [PERSON] et al. [27] studied the influence of tunnel foundation pit construction on the mechanical properties of the adjacent steel sheet pile wall through the finite element mode and found that the unpredictable displacement and bending moment occurred at the top of the wall during backfilling. The short-term water level prediction model of the support vector machine was established. This model could accurately predict the short-term water level, ensuring the construction of the steel sheet pile cofferdam [28]. [PERSON] et al. performed a sensitivity analysis to investigate the mechanism of the soil-structure interaction system by numerically simulating the behavior of the anchored sheet pile wall structure during excavation and backfill construction [29]. The geological and environmental conditions of hydro-engineering projects could lead to major construction accidents in cofferdams, and the influence of the tunnel foundation pit construction on adjacent cofferdams is still an urgent subject to be studied. In this study, the large-span steel sheet pile cofferdam in the Suzhou Yinshan Lake Tunnel Project was taken as the research object. The finite difference software FLAC3D 6.0 was used to establish a three-dimensional numerical analysis model of open-cut tunnel construction and adjacent steel sheet pile cofferdams. By comparing the numerical simulation results with the field monitoring results, the influence of tunnel construction on the mechanical properties of steel sheet pile cofferdam construction could be studied.