土岩深基坑桩-撑-锚组合支护体系变形特性

摘要

以青岛地区特有的土岩组合地质条件为背景,通过Plaxis有限元模拟和现场监测相结合的方法,探讨土岩组合深基坑中围护桩、钢支撑与锚索组合支护体系的协同作用及基坑变形规律.通过不同支护形式的对比分析得到围护桩桩身水平位移、基坑周边地表沉降分布规律;从开挖步、钢支撑预应力及锚索预应力的变化分析得到围护桩桩身水平位移、弯矩及剪力的分布规律.研究结果表明:基坑变形和周边地表沉降模拟结果与实测值结果吻合较好,基坑的变形主要发生在基坑上部软弱土层,采用桩–撑–锚组合支护体系在青岛地区具有很好的实用性.研究成果可为类似土岩结合地区深基坑支护设计提供参考.%Based on the unique soil-rock combinational geological features of Qingdao, the cooperative effects and deformation laws of combined support system of fender pile-steel support-anchor cable for deep foundation pit in soil-rock combination were discussed through Plaxis finite element simulation and field monitoring. Meanwhile, the horizontal and ground displacement distribution was obtained by contrasting different support types; and the distribution laws of horizontal displacement, bending moment and shear force of the pile were analyzed by changing the excavation steps, and pre-stress of steel support and anchor cable. The results show that the calculated results agree well with the test results in deformation and ground settlement, while the main deformation occurs in soft soil strata in rocky area. The application of pile-support-anchor system is practical in Qingdao. The research results can provide reference for deep foundation pit supporting design in similar geological conditions.