针对盾构隧道开挖对邻近桩基础的影响这一城市地下交通隧道建设中的难题,首先对盾构隧道开挖的三维数值模拟方法进行了探讨,此基础上分析了当隧道与邻近单桩基础之间相对位置不同时,隧道开挖对桩的影响及其规律,并与已有的现场监测及模型实验结果进行了对比,对其机理进行了探讨.研究表明：桩的端承力和侧摩阻力的变化趋势和隧道位置密切相关;当隧道位于桩正下方时,桩端承力持续减小,侧摩阻力增大,较小的地层损失就能导致桩端承力丧失;当隧道位于桩旁侧一定水平净距离（约半倍隧道直径）外时,隧道开挖将导致桩端承力不断增大,侧摩阻力减小,甚至产生负摩阻力;当隧道位于桩侧中部深度时,还将引起较大的桩身弯矩;随着隧道与桩之间水平距离的增加,隧道开挖带来的影响也迅速降低.

 It is important to consider the effect of shield tunneling on adjacent pile foundation during the construction of urban tunnels.This paper discusses the methods of three-dimension numerical simulation of shield tunneling,and then analyzes the effect of tunneling on the adjacent single-pile foundation and the corresponding affecting rules in terms of different relative position between the tunnel and the adjacent pile.The analytical results are finally compared with those from field monitoring and laboratory model testing.It is indicated that（1） both the end bearing force and the side friction of the pile highly relate to the tunnel position;（2） when the tunneling is just below the pile toe,the end bearing force continuously decreases and even disappears at a small ground loss,while the side friction gradually increases;（3） when the tunneling is at the side of the pile（about half tunnel diameter away from the pile）,the end bearing fore continuously increases,while the side friction decreases even to a negative value;（3） when the tunnel is at the mid-depth position of the pile side,large bending moment of the pile may occur;and（4） the impact of tunneling significantly decreases with the increase in horizontal distance between the tunnel and the pile.