This paper took a parking lot project in Shenzhen as an example. Considering the features including piles' amount is large, the distance between piles and tunnels is very close and tunnels are located under the spot, this paper constructed a good-sized three-dimensional finite element model. The piles' influence on the underlying tunnel during the three sections including foundation's construction, load application and parking lot operation. The simulation result shows that: in piles' construction section, piles on both sides of the existing tunnel lead to vertical subsidence, horizontal convergence pointing to the inside space and overall distortion of the tunnel structure. Tunnel structure's deformation features in other two sections are similar to the one in construction section, and deformation is mainly caused by load application, while deformations in other two sections are small. Besides, the rationality of the simulation is demonstrated by the accordance between the computed result and practical monitoring data.%依托深圳地铁某停车厂工程,针对其工程桩数量众多、距离隧道极近、场地正下方附存铁路隧道等特点建立大型三维有限元模型,以数值模拟的方式分析桩体施工、荷载施加、停车场运营阶段对于下部既有隧道的影响.模拟计算结果表明,桩体施工阶段,既有隧道两侧桩基造成隧道结构竖向下沉,横向洞内收敛,整体出现扭曲.桩基础在荷载施加与运营阶段隧道结构变形规律与桩体施工阶段相近,其中,施工阶段引起变形较小,荷载施加引起变形占主要部分,停车场运营期仍会发生小变形.计算结果与现场监测数据基本一致,从而说明模型的合理性.
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