深基坑开挖可能引起围护结构与周围土体的变形, 而这些变形对各种影响因素具有不同的敏感程度. 以上海长江西路越江隧道新建工程为例, 根据实际土层分布建立了里程 NK0+534.100 处基坑体系横截面的几何模型, 使用有限元分析软件 ABAQUS 进行了基坑开挖过程的数值模拟, 分析了基坑施工过程中地下连续墙水平位移随深度的变化特征, 对比研究了现场监测数据与数值模拟结果. 选取地下连续墙厚度、窄基坑开挖深度、窄基坑开挖宽度 3 个影响因素, 并对每个因素取 3 个水平, 使用正交试验和正交表 L$_{9}$(3$^{4})$ 实现了 9 种不同情况的数值模拟试验, 并基于这些因素对地下连续墙水平位移的影响进行极差分析和方差分析. 结果表明: 数值模拟结果与现场监测数据吻合程度较好; 对地下连续墙水平位移影响程度由大到小的因素依次为地下连续墙厚度、 窄基坑开挖深度、窄基坑开挖宽度; 地下连续墙厚度-地下连续墙的水平位移呈负相关, 窄基坑开挖宽度、深度-地下连续墙水平位移呈正相关. 研究成果对基坑施工过程中围护结构的变形分析具有一定的参考价值.

Excavation of deep foundation pit may result in deformation of supporting structures and surrounding soils. These deformations have different sensitivities to different influencing factors. Taking Shanghai Yangtze River Tunnel Project as an example, this study establishes a geometrical model of the foundation pit excavation based on actual soil distributions. The finite element analysis software ABAQUS was used to simulate the excavation process of the foundation pit. Horizontal displacements of the diaphragm wall were examined during excavation. Comparison between the field monitoring data and the simulated ones was made. Three factors influencing horizontal displacement of the diaphragm wall were chosen: thickness of diaphragm wall and width/depth of narrow excavation, and for each factor tree levels were set. Thus a total of 9 numerical simulation tests were performed based on the orthogonal table L$_9$(3$^4$) using an orthogonal test technique. Range analysis and variance analysis were then made. The simulation results are close to the field monitoring data. Factors affecting horizontal displacement of diaphragm wall in a descending order are thickness of diaphragm wall, depth of excavation of narrow foundation pit, and width of excavation of narrow foundation pit. Thickness and horizontal displacement of the diaphragm wall show a positive relation, while width and depth of excavation of the narrow foundation pit and horizontal displacement of the diaphragm wall show a negative relation. The results may provide references in analyzing deformation of retaining structures in foundation pit construction.