Influence of deep-buried shield tunneling construction undercrossing existing railways

The number of cross-project constructions where new subway lines undercross existing railways using shield tunneling is increasing with the urban comprehensive transportation construction. Previous studies have analyzed the impact of shield tunneling on railway deformation through numerical simulation and on-site monitoring, with tunnel depths generally below 20 m. Due to the time-space effect during tunnel construction, the influence of tunneling at depths exceeding 20 m on railway deformation characteristics remains unclear. This research takes the example of a highway shield tunnel undercrossing the Beijing-Guangzhou Railway in Wuhan city and uses automated monitoring methods to analyze the influence of deep-buried shield tunneling construction on the settlement of existing railway tracks, subgrades, and the inclination of the railway catenary system. The study revealed that for deep-buried shield tunneling construction, the deformations of the railway subgrades, tracks, and overhead contact system have a certain lag. The settlement troughs of the railway tracks and subgrades exhibit a V-shaped or U-shaped pattern, with an affected width of approximately 75 m, which is significantly larger than that of ordinary shallow-buried shield tunnels. The research findings can provide data support and reference for similar deep-buried shield tunneling projects that undercross existing railways.