摘要
基坑开挖对坑内工程桩的影响不可忽视。基于工程试桩实测资料验证的有限元参数,对地面加套管试桩及基坑开挖条件下不同长度单桩进行有限元计算,研究了深厚软土地区在以常规试桩法得到的单桩极限承载力设计的桩基础的承载及变形性状。计算结果表明,基坑开挖条件下坑底工程桩侧阻和端阻异步发挥的现象明显。设计工作荷载下,长度超过40 m的桩的端阻比几乎为0。同时,桩身侧阻呈"R"形分布,长度大于80 m的单桩桩身下部甚至还存在一定的拉力,桩身下部存在较大范围的负摩阻区。考虑开挖条件下侧阻分布特点的沉降计算值要较Geddes假设分布模式下的沉降值更接近于实测结果。
The effect of deep excavation on piles beneath the excavation bottom should not be ignored.Based on the verified finite element parameters of a project in Tianjin,load tests with sleeve and under excavation of piles with different lengths are analyzed.The characters of load transfer and settlement of piles designed by conventional pile load tests are analyzed in deep soft soil region.From the finite element analysis results,some conclusions are drawn as follows.The shaft resistance and tip resistance of piles beneath the excavation bottom are mobilized asynchronously.The tip resistance ratios are almost zero under working loads for piles longer than 40 m.The shaft resistance distributes in a ＇R＇ pattern.There are even tensile forces in the lower part of piles under working loads.The friction on the lower part is negative for piles longer than 80 m.The settlement calculated considering shaft resistance distribution influenced by excavation is closer to observed data than that of Geddes solution.
出处
《岩土力学》
EI
CAS
CSCD
北大核心
2011年第10期3089-3096,共8页
Rock and Soil Mechanics
基金
国家自然科学基金资助项目(No.50878144)
国家重点基础研究发展计划(973计划)资助项目(No.2010CB732106)
关键词
基坑开挖
荷载传递
有限元分析
沉降计算
excavation
load transfer
finite element analysis
settlement calculation
