顶推法架桥阶段桩基对邻近区间隧道影响的三维有限元分析

3D-FEM Analysis of Effect of Piers’ Foundation on Adjoining Tunnels during Girder Installation with Incremental Launching Method

摘要: 顶推法架设钢箱梁在桥梁建设中广泛应用。但是顶推法架设过程中桥梁主墩的短期荷载会随着架设阶段进展发生变化，部分主墩的短期荷载甚至大于主墩的设计长期荷载。对于主墩邻近区域存在运营盾构隧道的情况，需要评估施工阶段主墩沉降对盾构隧道的影响，以确保隧道的安全。本文对上海某跨线桥工程采用钢箱梁顶推法时的主墩沉降对邻近地铁隧道的影响采用Midas-GTSNX软件进行了三维有限元分析。分析中按架桥施工各阶段主墩短期荷载下隧道位移和运营期长期荷载下的隧道位移分别进行了计算，发现施工期间的隧道位移小于设计荷载的隧道位移，论证了顶推法的可行性。最后将计算结果和现场监测结果进行了对比，证明顶推法施工对邻近隧道的影响在可控范围内，是成功的。本文可为类似工程提供借鉴。

Abstract: Incremental launching method is becoming increasingly popular to build steel box girders. But when using this method, the load on main pier shall change during launching, and sometimes shall even be larger than the design service load. Therefore, for the safety of neighbouring tunnels, if any, it is necessary to appraise the effect of the settlement of pier foundation on tunnels before launching. Based on the construction of a bridge crossing metro tunnel in Shanghai, using the software Midas-GTSNX, this paper has presented a 3D finite element analysis of the effect of foundation settlement on neighbouring tunnels. This analysis includes the calculation of the tunnel displacements due to short-running and long-running loads, and the result shows that the displacement due to short-running load shall be less and proves that it is feasible to adopt incremental launching method. Finally, this paper has made a comparison between calculation and site measurement and shows that the effect of bridge launching on tunnels has been under the limit and the launching is a success. This method can be a reference for other similar projects.