路堤荷载作用下柔性桩复合地基的沉降分析  

Settlement analysis of flexible pile composite foundation under embankment load

作　　者：陈盛原 叶华洋 张伟锋[1] 韦未[1] CHEN Sheng-yuan;YE Hua-yang;ZHANG Wei-feng;WEI Wei(College of Water Conservancy and Civil Engineering,South China Agricultural University,Guangzhou,Guangdong 510642,China;Hydroelectric College,Hohai University,Nanjing,Jiangsu 210098,China)

机构地区：[1]华南农业大学水利与土木工程学院,广东广州510642 [2]河海大学水利水电学院,江苏南京210098

出　　处：《岩土力学》2020年第9期3077-3086,共10页Rock and Soil Mechanics

基　　金：国家级大学生创新训练项目(No.201710564365);广东省水利科技创新重点项目(2015-16);广东电网有限责任公司科技项目(No.032000KK52160015)。

摘　　要：为了寻求路堤荷载下柔性桩复合地基沉降计算的简便方法,基于已有的研究成果,将桩侧摩阻力分布简化为分段线性模式,根据桩长与临界桩长的大小关系,结合桩−土−垫层三者在交界面上的应力与压缩变形协调条件,运用单位元法推导了柔性桩复合地基加固区的沉降计算公式,并采用分层总和法计算复合地基下卧层的沉降量。结合工程实例对计算结果进行验证,结果表明:采用理论方法计算的柔性桩复合地基沉降量与现场实测沉降结果吻合较好,证明理论计算方法的合理性,且能较好地反映路堤荷载作用下柔性桩复合地基的工作性状。进一步分析表明:在临界桩长范围内,桩与桩间土相互作用,最大限度发挥了复合地基桩间土的承载能力;此外,由于桩侧负摩阻力对桩体有拖拽作用,桩身轴力在桩体中性面位置处达到最大值。因此,在工程设计中要高度重视和运用临界桩长和中性面的概念。This paper is aiming to find a simple method for the settlement calculation of flexible pile composite foundation under embankment load.Firstly,the side frictional distribution of pile is simplified into a piecewise linear model based on the existing research results.Then,according to the relationship between the length of pile and the critical length of pile,combined with the coordination conditions of stress and compression deformation at the interface of pile-soil-cushion,settlement calculation formulas of flexible pile composite foundation reinforcement area are deduced by using the unit element method,and the settlement of underlying layer of composite foundation is calculated by layer summation method.Finally,the proposed approach is used to predict the settlement of an engineering example,and it is found that the predictions are in accordance with measurements,demonstrating that the approach is available in reflecting the working behavior of the flexible pile composite foundation under embankment load better.Further analysis shows that within the critical length of pile,the bearing capacity of soil between piles in composite foundation is maximized by the interaction of piles and soil.In addition,due to the drag effect of the negative frictional resistance,the axial force of pile at the position of the neutral plane reaches the maximum.Therefore,the concept of critical pile length and neutral plane should be highly valued and applied in engineering design.

关 键 词：复合地基 沉降分析 柔性桩 路堤荷载 临界桩长 

分 类 号：TU473[建筑科学—结构工程]