某邻地铁超大直径圆环撑软土深基坑变形特性分析

Analysis on Deformation Characteristics of Super Large Diameter Ring Bracing Deep Foundation Pit in Soft Soil near Subway

以深圳都市茗荟花园(二期)基坑为工程背景,对超大直径圆环撑软土深基坑支护桩侧向变形、地面沉降、支撑轴力等监测数据进行了分析,分析了基坑变形的时空分布特征,探讨了基坑变形与开挖深度、软土厚度的关系,得出下列结论:(1)支护结构的最大变形随着基坑开挖深度的增加而逐步增大,基坑开挖至坑底后,整体变形最大位置位于基坑两侧长边中部采用圆环支撑部位。(2)咬合桩+刚度较大的超大直径环形钢筋砼撑结构应用于软土深基坑中在变形控制及减小基坑工程对周边变形影响等方面均非常有效。(3)随着基坑向下不断开挖,三种方式所反映出的支护结构的最大水平位移量均逐渐增加,但变化幅度有一定的差异。

Taking the foundation pit of Minghui Garden(phase II) in Shenzhen reclamation area as the engineering background,the monitoring data of lateral deformation,slope top displacement and support axial force caused by foundation pit construction were analyzed.The temporal and spatial distribution characteristics of deep foundation pit deformation in soft soil were discussed,and the relationship between foundation pit deformation and excavation depth as well as soft soil thickness was discussed.The conclusions were as followed:(1) The maximum deformation of the supporting structure gradually increases with the increase of the excavation depth of the foundation pit.After the foundation pit was excavated to the bottom of the pit,the maximum overall deformation was located at the middle of the long side on both sides of the foundation pit,which was supported by a ring.(2) The application of bite pile +super large diameter ring reinforced concrete support structure with large stiffness in soft soil deep foundation pit was very effective in deformation control and reducing the influence of foundation pit engineering on surrounding deformation.(3) With the continuous excavation of the foundation pit downward,the maximum horizontal displacement of the support structure reflected by the three methods gradually increases,but the variation range was different.