本文根据深圳地铁7号线笋岗站–洪湖站区间左线隧道穿越彩虹桥的桩基工程案例，借助MIDAS-GTS有限元软件，建立三维模型，对上下重叠隧道先后穿越城市高架托换桩基的过程进行模拟分析，得出托换桩基变形的规律。并在工程案例的基础上，建立三组模型，分析重叠隧道开挖的先后顺序、托换桩基的长度、上下两隧道的间距等因素对托换桩基变形的影响。
Based on the pile foundation engineering case of left line tunnel between Sungang station and Honghu station of Shenzhen Metro Line 7 passing through Caihong bridge, this paper establishes a three-dimensional model with the help of midas-gts finite element software to simulate and analyze the process of upper and lower overlapping tunnels successively passing through urban elevated underpinning pile foundation, and obtains the deformation law of underpinning pile foundation. On the basis of engineering cases, three groups of models are established to analyze the influence of the excavation sequence of overlapping tunnels, the length of underpinning pile foundation and the distance between the upper and lower tunnels on the deformation of underpinning pile foundation.
