基于FLAC3D地铁车站基坑开挖的变形规律研究

Research on deformation law of subway station foundation pit based on FLAC3D

文章运用FLAC3D有限差分软件对合肥轨道交通2号线潜山路车站基坑工程开挖全过程进行数值模拟,计算中土体采用摩尔-库伦弹塑性模型,围护结构采用实体单元,围护结构与土体的接触面采用接触面单元。通过分析计算结果与监测数据可得:围护结构的最大水平位移发生在基坑的中部,随着基坑不断开挖,围护结构最大水平位移逐渐下移,其最大变形位置位于开挖面附近,呈现两端小、中间大的"抛物线"分布;基坑外地表沉降是一种典型的凹槽形沉降,最大沉降值发生在距基坑边缘10m处;数值模拟结果与监测数据基本一致,且变形规律及趋势相吻合,可为类似工程的设计与施工提供参考。

The whole process of the excavation of foundation pit engineering construction of Qianshan Road Station of Hefei No. 2 rail transit line is simulated numerically by using the FLAC3D finite difference software. In the calculation, Mohr-Coulomb elastoplastic model is used to calculate the soil, the entity unit to calculate the retaining structure, the contact elements to calculate the contact surface between retaining structure and soil. The calculation results are compared with the monitoring data. The results show that the maximum horizontal displacement of retaining structure occurs in the middle of the foundation pit; with the excavation of foundation pit, the maximum horizontal displace- ment of retaining structure moves down gradually; the maximum deformation position is near the ex- cavation surface, and the deformation shows a ＂parabola＂ distribution which is big in the middle and small at both ends; the ground settlement outside is a kind of typical groove shape of settlement, the position of the maximum settlement value is 10 m away from the foundation pit edge. The numerical simulation results and monitoring data are almost the same, and the deformation law and trend are consistent. The study can provide a reference for the design and construction of similar projects.