Abstract: With the accelerated development of urban underground space, deep excavation projects adjacent to railway lines are increasingly common. The stress release in soil and groundwater seepage induced by excavation often lead to surrounding soil deformation, which may cause settlement of railway subgrades and pose a potential threat to train operation safety. This study presents the deep excavation of Danshuichi Station on Wuhan Metro Line No. 12 as a case study. Using FLAC3D numerical simulation software, a three-dimensional finite difference model was established to dynamically simulate the entire process of excavation and support. The influence of deep excavation on the settlement of adjacent freight railway subgrade was systematically analyzed. The results indicate that the settlement curve of the railway subgrade first increases and then decreases, with a maximum settlement value of 3.32 mm occurring at a distance of 19.76 m from the long side of the excavation. This settlement is within the allowable deviation limits of railway track geometry, indicating that the current construction plan has a controllable impact on the safety of the operational railway. It was also found that each excavation step causes significant settlement in the soil near the railway. Therefore, it is recommended to strengthen deformation monitoring of the adjacent subgrade during excavation and implement dynamic feedback control measures to ensure construction and operational safety. This study can provide a reference for the design and construction of similar deep excavations near railways.

Key words: Deep Excavation, Existing Railways, Subgrade Settlement, Numerical Analysis