基于强度折减法的圆形顶管井基坑变形及稳定性分析
Analysis on Deformation and Stability of Circular Pipe-jacking Shaft Foundation Pit Based on Strength Reduction Method
高程鹏 1杨峰 1卢瀚 1李楠1
作者信息
- 1. 上海市政工程设计研究总院(集团)有限公司,上海市 200092
- 折叠
摘要
现行规范中有关圆形顶管井基坑的设计方法主要采用平面弹性支点法,考虑到三维空间下环形基坑支护结构的拱效应和周边土体的土拱效应,平面计算结果较实际偏于保守.为此,基于强度折减法,通过建立圆形顶管井基坑的二维、三维有限元计算模型,得到了基坑安全系数和变形量,并将计算结果与规范方法进行了比较分析.分析表明:在深径比h/r＞0.9时,坑底土主要产生隆起变形;当深径比h/r小于0.9并逐渐减小后,坑底出现圆弧滑动面,土体破坏呈整体滑移模式;在三维模型下,围护结构的拱效应阻隔了坑边超载对圆弧滑动面分布的影响,周边土体的土拱效应减小了地表沉降量和围护结构变形量;基于强度折减法的基坑安全系数是规范方法中坑底抗隆起安全系数的2～3倍.
Abstract
The design method of circular pie-jacking shaft foundation pit is the plane elastic fulcrum method in the current specification.Considering the arch effect of supporting structure of ring foundation pit and the soil arch effect of surrounding soil body under 3D space,the result of plane calculation is more conservative than the actual one.Therefore,based on the strength reduction method,the 2D and 3D finite element models of ring pipe-jacking shaft foundation pit are established to obtain the safety coefficient and deformation of foundation pit The computed result is analysed and compared with the standard method.The analysis shows that when the depth to diameter ratio h/r was larger than 0.9,the soil at the bottom of the pit is uplifted to deform When the depth to diameter ratio h/r is less than 0.9 and gradually decreases,the circular sliding surface appears at the bottom of pit.The soil failure is in the overall sliding mode.Under 3D model,the arch effect of building envelope will obstruct the influence of the pit-side overload on the distribution of the circular sliding surface The soil arch effect of the surrounding soil reduces the ground settlement and the envelope deformation The safety factor of foundation pit based on strength reduction method is 2～3 times of the anti-uplift safety factors at the pit bottom in the standard method.
关键词
圆形顶管井基坑/强度折减法/稳定性分析/有限元计算/深径比Key words
circular pipe-jacking shaft foundation pit/strength reduction method/stability analysis/finite element analysis/depth to diameter ratio引用本文复制引用
出版年
2024
NETL
NSTL
万方数据