Abstract: With an accelerated development of infrastructure construction in Yangtze River Delta, there are more and more engineering projects constructed near the existing railway lines. The related construction processes such as deep excavation and backfill might induce the excessive deformation of the adjacent railway subgrades. This might finally affect the safety operation of these railway lines. Based on the reconstruction project of the Qingyang Port Channel Section of the BeijingShanghai Railway, this paper presents the numerical analysis to evaluate the impact of deep excavation and rainfall on the adjacent railway subgrade. Studies have shown that after the deep excavation, the soil surrounding the excavated area and the railway subgrade will deform to a certain extent. The lateral deformation of the excavation supporting structure demonstrate a pattern of larger at upper portion and smaller at lower portion, which is similar to the deflection in a cantilever beam. The maximum displacement occurs at the bottom of the railroad embankment. When an unfavorable condition, such as rain, is encountered, the strength of the surficial soil of at the excavated area and the roadbed will be weakened. When the strength reduction coefficient is in the range of 0.5~0.6, the overall displacement of the railway roadbed will increase sharply. In actual projects, it is necessary to strictly control the deep excavation area in stages, improving the railroad track monitoring in the process, and strictly implement the rail inspection system during and after the precipitation to ensure the safety of railway operations.

Key words: Deep Excavation, Railway Subgrade, Numerical Simulation, Rainfall Impact