Journal of Hebei University of Water Resources and Electric Engineering

Journal of Hebei University of Water Resources and Electric Engineering ›› 2020, Vol. 30 ›› Issue (1): 7-13.DOI: 10.16046/j.cnki.issn2096-5680.2020.01.002

• Technology Theory and Application • Previous Articles     Next Articles

Displacement Analysis of Caisson-piles Composite Foundations

ZHANG Kai 1，2，LIU Xu-kai 2，ZHOU Yan3，GUAN Qing-hai 3，LI Zi-lin4   

  1. 1.School of Civil Engineering，Tianjin University，300072，Tianjin，China;
    2.Tianjin Municipal Engineering Design & Research Institute，300191，Tianjin，China;
    3.Tianjin Key Laboratory of Civil Structure Protection and Reinforcement，Tianjin Chengjian University，300384，Tianjin，China;
    4.Hebei University of Water Resources and Electric Engineering，061001，Cangzhou，Hebei，China

  • Received:2019-09-19 Revised:2019-11-22 Online:2020-03-31 Published:2020-04-30

带桩沉井复合基础变位分析

张 凯1，2，刘旭锴2，周 燕3，管青海3，李自林4   

  1. 1.天津大学建筑工程学院，天津市南开区卫津路92号 300072;
    2.天津市市政工程设计研究院，天津市和平区营口道239号 300191;
    3.天津城建大学天津市土木建筑结构防护与加固重点实验室，天津市西青区津静路26号 300384;
    4.河北水利电力学院土木工程学院，河北省沧州市重庆路1号 061001

  • 作者简介:张 凯(1976-)，男，河南南阳人，高级工程师，天津大学在读博士后，从事桥梁科研及设计工作｡E-mail:394756035@qq.com
  • 基金资助:
    国家自然科学基金项目(51208337);; 天津市自然科学基金项目(17JCYBJC22300,18JCQNJC08300);; 天津市应用基础与前沿技术研究计划(15JCYBJC48800);; 天津市交通运输科技发展计划项目(交委2014-18);; 道路结构与材料行业重点实验室基金项目(310821171114);; 天津市企业博士创新项目择优资助计划(2015-003)

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Abstract: According to the ratio of load distribution between pile foundation and caisson，the main and secondary stressed members are determined，and the simplified calculation model of caisson-piles composite foundation is established.Based on the mechanics balance condition of foundations，the calculation formula for caisson-piles composite foundation is derived.The strength failure limit state of the caisson-piles composite foundation is discussed.The influence of the soil creep effect to the composite foundation is analyzed.Based on the engineering examples，the different displacement of the foundation for the caisson and caisson-piles foundation are analyzed and compared.The results show that the horizontal displacement of the foundation can be reduced by about 20~30%and the rotation angle of the box can be reduced by about 35~45%compared with the caisson foundation.The soil properties behind the caisson-piles foundation significantly affect the displacement of the foundation.The soil in the back of the caisson gradually improves from the flow plastic state to the hard state，the horizontal displacement at the top of the foundation will be reduced by 50~70%，and the box angle will be reduced by 20~50%.The distribution relationship of the horizontal load for the caisson-piles composite foundation is related to the stiffness of the soil in the back of the caisson and the stiffness ratio of the pile foundation.The load shared by the back soil of the caisson increases with the increase of the stiffness of the back soil.Compared with the caisson foundation，the caisson-piles composite foundation can reduce the deformation of the foundation，but there is still a problem of insufficient bearing capacity of the soil behind the caisson，reinforcement measures should be taken to improve the performance of the soil and raise the bearing capacity of the soil，also further reduce the long-term and short-term deformation of the foundation.

Key words: caisson-piles composite foundation, caisson foundation, analytical method, foundation displacement, soil creep effect, bearing behavior

摘要： 根据桩基础与沉井之间的荷载分配比例关系,确定了主次受力构件,构建了带桩沉井复合地基基础简化计算模型;基于基础的力学平衡关系,推导了带桩沉井基础的计算公式;讨论了带桩沉井的破坏极限状态;分析了持续高水平荷载作用下土体流变效应对带桩沉井复合基础的影响。基于工程实例,分析比较了沉井基础及带桩沉井复合基础变位差异。研究结果表明:带桩沉井结构与沉井基础相比,基础顶部水平位移可以减小20%～30%,箱体转角可以减小35%～45%;沉井后背土体性质显著影响基础的变位,沉井后背土体由流塑状态逐步改善到坚硬状态,基础顶部水平位移将减小50%～70%,箱体转角减小20%～50%;带桩沉井基础中水平荷载的分配关系与沉井后背土体的刚度、桩基础刚度比例有关,沉井后背土体分担的荷载随着后背土体刚度增加而加大;软土地基带桩沉井基础相比沉井基础虽然能够降低基础的变形,但仍存在台后土体承载能力不足的问题,应对箱体背部采取加固措施改善土体性能,以提高土体承载能力并进一步降低基础的长期变形与短期变形。

关键词: 带桩沉井复合基础, 沉井基础, 解析方法, 基础变位, 土体流变效应, 承载性能

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