研究目的：随着临近高铁的上跨和下穿道路工程日益增多，大量新建道路等基坑工程位于高铁路基或桥梁保护范围以内，使得高铁结构不可避免地受到基坑施工的影响，在软土地区更为严重。本文以天津地区临近某高铁的道路下穿高铁工程为背景，运用ABAQUS软件建立三维数值分析模型，对不同距离、不同挖深、不同封闭式路堑节段的基坑施工过程进行了数值仿真分析。研究结论：(1)基坑施工引起的高铁路基和框构桥梁的附加差异沉降量、轨道的平顺性均满足规范要求。基坑开挖会引起高铁路基和框构桥的隆起变形，封闭式路堑浇筑后隆起变形减小；(2)施工过程中，基坑开挖为关键风险阶段，当施工至远离高铁72 m以外的基坑时，剩余节段施工对高铁基本无影响；(3)施工过程中应尽量减小每次的开挖量，按照每节独立开挖浇筑的工序进行，尽可能地将施工影响控制在极小的范围内，以免影响铁路运营的安全性和舒适性；(4)本文研究成果可以为临近高铁工程建设提供一定的理论依据，对软土地区临近高铁的基坑开挖有一定的参考意义。
Research purposes: As adjacent projects that cross over or going through under high-speed railway are gradually increasing, and lots of new highway foundation pit work located around high-speed railway subgrade or bridge protection sphere, the railway will inevitably be influenced by those engineering constructions. Based on a highway project adjacent to a high-speed railway, the 3d numerical analysis model has been built by using ABAQUS software, the construction process of different distance, different excavation depth and different u-shape groove segments is analyzed.
Research conclusions: (1) The additional differential settlement and track irregularity meets the code requirements. The subgrade and frame bridge will rebound induced by pit excavation, and the rebound deformation will decrease after u-shape groove pouring. (2)During the whole construction process，the pit excavation is the key risk stage，the residual u-shape groove segment construction will have no effect when the pit work 72m away from high-speed railway has finished. (3)In order to reduce the influence to the existed railway and ensure the safety and comfort of railway, the railway foundation deformation influenced by pit excavation should be fully considered and limited to a small range, decrease each step excavation volume. According to reasonable procedure, independent sequential pit excavation and pouring are performed. (4) This paper provides the theoretical evidence for the construction of the adjacent high-speed railway project and also provides the valuable reference to the study on the foundation pit excavation on adjacent high-speed railway in soft soi1 area.
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