关键词: 盾构施工, 桥梁基础, 数值模拟, 控制指标

Abstract: The influence of shielded transit tunnel construction on the existing bridge foundations is a very prominent issue. This paper presents a case history of on the shielded section of Ningbo Metro Line 8 under crossing the urban viaduct. The corresponding shielded tunnel construction model is established by using the Midas GTS NX 3D finite element software to analyze the deformation at the top of a viaduct pier. The results indicate that, during the shield construction process, the horizontal displacement (transverse and longitudinal) at the top of the bridge pier first increases, then decreases, and then increases, which exhibiting a bimodal curve. The peak moment of the former is earlier than that of the latter. While the vertical displacement (upheave and settlement) continuously increases, approaching a linear curve. According to the displacement results of the pier top obtained by the numerical analysis, the corresponding displacement control indies are recommended. The feasibility and rationality of the above control indicators are verified by combining with the displacement monitoring data of the viaduct pier during shielded transit tunnel construction, which can provide a reference for the similar shielded tunnel excavation projects in Ningbo areas.

Key words: Shielded Transit Tunnel Construction, Bridge Foundation, Numerical Simulation, Control Indies