Abstract: To obtain the influence pattern of a new shield tunnel underpass the existing operating tunnel, the construction case history of the Xiamen Metro Line No. 4 underpasses an existing operating highway tunnel is presented in this paper. The commercial software Midas GTS NX to simulate the whole process of the shield tunnel under passing the existing operating tunnel in the left and right lines respectively, and to investigate the influence of the under passing tunnel angle and other factors on the mechanical behavior of the operating tunnel, the research results show that: as the shield tunnel continues to excavate, the results show that the existing tunnel settlement increases as the shield tunnel is excavated, but the existing tunnel settlement only changes significantly when the shield tunnel is excavated directly below the operating tunnel; the final settlement of the existing tunnel increases as the angle of the underpass tunnel decreases. The results of the study can provide a scientific reference for similar projects.

Key words: Shielded Tunnel, Underpass, Operational Tunnels, Numerical Simulation, Deformation Pattern