为快速分析基坑开挖时复合地基及“双洞效应”对下方既有双线地铁隧道竖、横向位移的影响,首先，基于Mindlin位移解和Winkler地基模型,推导出复合地基中桩的侧摩阻力作用下单线隧道的竖、横向附加荷载,从而计算得到单线隧道竖、横向位移。然后，采用迭代法计算得到的“双洞效应”引起的隧道竖、横向位移叠加得到双线隧道总竖、横向位移，并与前人理论计算结果、监测数据对比验证。最后,分析桩参数、隧道位置改变对桩侧摩阻力和“双洞效应”引起隧道竖、横向位移的影响。研究结果表明: 1）与前人理论计算结果相比,本文理论计算结果与实测数据更吻合,且提高原有2阶段分析方法运算效率28%以上; 2）桩侧摩阻力和“双洞效应”对隧道竖、横向位移的影响是不可忽略的; 3）仅考虑上方基坑开挖对既有双线隧道位移的影响时,在施工条件和规范允许情况下,应尽量减少预先设计的两隧道之间距离,并合理选取复合地基中桩的长度; 4）迭代法比一次性法更加合理、精确，特别是计算横向“双洞效应”引起隧道横向位移时，应尽量采用迭代法计算。

In order to rapidly analyze the influence of composite foundation and "doubletube effect" on the vertical and lateral displacements of existing doubletube metro tunnel during foundation pit excavation, the vertical and lateral additional loads of singletube tunnel under lateral resistance of pile in composite foundation is deduced to calculate the vertical and lateral displacements of singletube tunnel based on Mindlin′s solution of displacement and Winkler foundation model. The total vertical and lateral displacements of doubletube tunnels can be obtained by superposition of tunnel vertical and lateral displacements caused by "doubletube effect" calculated by iterative method, which is verified by comparison with the previous theoretical calculation results and monitoring data. Finally, the influence of the pile parameters and tunnel positions on tunnel vertical and lateral displacements caused by pile lateral resistance or "doubletube effect" is analyzed. The results show that: (1) Compared with the previous theoretical calculation results, the theoretical calculation results in this paper are more consistent with the monitored data, and the calculation efficiency is more than 28% higher than that of the original〖JP〗 twostage analysis method. (2) The influence of pile lateral resistance and "doubletube effect" on tunnel vertical and lateral displacements are not negligible. (3) Considering only the influence of foundation pit excavation on the displacement of existing doubletube tunnel, the distance between two predesigned tunnels should be reduced as far as possible, and the length of pile in composite foundation should be reasonably selected when construction conditions and rules permit. (4) The iterative method is more reasonable and accurate than onetime method, especially when calculating tunnel lateral displacement caused by lateral "doubletube effects".