摘要
为建立能考虑桩土滑移特性和桩间土非均匀压缩变形特征的路堤下刚性桩复合地基沉降计算方法,以均布荷载下等桩长刚性桩复合地基中单桩等效加固单元体为研究对象,基于桩土相互作用的上部负摩阻塑性区、中部协调变形弹性区和下部摩擦承载塑性区三区段模式,采用剪切刚度和极限摩阻力随法向应力变化的等单位长度极限剪切位移理想弹塑性模型,建立了弹性区非线性和塑性区非均匀的桩侧摩阻力分布模型;考虑桩土滑移特性及桩间土非均匀压缩变形特征,根据单元体桩土荷载传递微分方程,导出了表征路堤下刚性桩复合地基性状的沉降和桩土应力比的解析表达式,分析了路堤荷载及垫层柔度系数对沉降和桩土应力比的影响。研究结果表明:沉降随路堤荷载及垫层柔度系数的提高而增大;桩土应力比随垫层柔度系数的增加而减小,随路堤荷载的提高呈先增大后减小的变化趋势,据此提出了采用最大桩土应力比进行路堤下刚性桩复合地基承载力及沉降设计的技术原则。
To establish the settlement calculation method of rigid pile composite-foundation considering the pile-soil slip characteristics and unequal compression deformation of soil between piles under the embankment load,the equivalent reinforcement unit of single pile in rigid pile composite-foundation with equal length of pile under the uniform load was taken as a research subject.Based on the three-section distribution pattern of pile-soil interaction that contains the upper plastic zone of negative friction,the central elastic zone of coordinate deformation and the lower plastic zone of friction bearing,the elastic-plastic model of ultimate shear displacement with equal per unit length in consideration of the variation of shear stiffness and the ultimate friction with the influence of normal stress was adopted,and a distribution model for friction on pile-soil interface describing the nonlinear elastic-zone and inhomogeneous plastic-zone was developed.Considering the pile-soil slip characteristics and unequal compression deformation of soil betweenpiles,the formulas of the settlement of rigid pile composite-foundation and stress ratio of pile-soil under the embankment load were derived according to the pile-soil load transfer differential equations of the unit cell.What＇s more,the effect of the embankment load and the flexibility coefficient of cushion on the settlement and pile-soil stress ratio were analyzed.The results show that the settlement increases with the increasing of the embankment load as well as the flexibility coefficient of cushion.The pile-soil stress ratio decreases with the increase of the flexibility coefficient of cushion,whereas it increases at the beginning and decreases afterwards with the increase of the embankment load.The technical principle of the design of the bearing capacity and the settlement of rigid pile composite-foundation under the embankment load is put forward by the maximum stress concentration ratio.
出处
《中国公路学报》
EI
CAS
CSCD
北大核心
2018年第1期20-30,共11页
China Journal of Highway and Transport
基金
国家重点基础研究发展计划("九七三"计划)项目(2013CB036204)
中国铁路总公司科技研究开发计划项目(2014G003-B)
西南交通大学博士研究生创新基金项目(143300289)
关键词
道路工程
刚性桩复合地基
荷载传递模型
桩土滑移
沉降
桩土应力比
road engineering
rigid pile composite foundation
load transfer model
pile-soil rela-tive slip
settlement
pile-soil stress ratio
