Investigation of Underpass and Railway Track Settlements Induced by Shield Tunneling Through In Situ Test and 3D FEM Simulation

Railway track settlements are extremely important for the safe operation of trains. This study utilizes an in situ test and a three-dimensional finite element method (3D FEM) to investigate the settlement of underpasses and railway tracks caused by shield tunneling. First, the 3D FEM results are compared with field monitoring data. Second, the settlement variation of tracks during shield construction is analyzed. Finally, the effect of the tunnel–underpass distance is observed. A comparative study establishes the reliability of the achieved 3D FEM results, which showed the consistency of railway track settlement with that of the underpass top plate. Based on the cutter head location, the underpass and railway track settlements were divided into three stages. With an increase in the tunnel–underpass distance, the underpass and railway track settlements increased, and the speed of increase was significantly higher when the tunnel was beyond the scope of the underpass. When the tunnel axis was within the scope of the underpass, the settlement of the bottom plate > top plate > railway track, and the differences between them were relatively small. Contrarily, the top plate settlement was larger than the bottom plate, while the railway track settlement increased. In both cases, the difference between the top and bottom plate settlements gradually decreased as the tunnel–underpass distance increased. This study shows that the underpass may have a settlement control effect on the deformation of railway tracks of high stiffness.