“硬-软-硬”三层黏土上圆形基础的承载力分析

吴炳 郑敬宾 王栋

吴炳, 郑敬宾, 王栋. 2021. '硬-软-硬'三层黏土上圆形基础的承载力分析[J].工程地质学报, 29(6): 1744-1751. doi: 10.13544/j.cnki.jeg.2021-0091
引用本文: 吴炳, 郑敬宾, 王栋. 2021. "硬-软-硬"三层黏土上圆形基础的承载力分析[J].工程地质学报, 29(6): 1744-1751. doi: 10.13544/j.cnki.jeg.2021-0091
Wu Bing, Zheng Jingbin, Wang Dong. 2021. Study of bearing capacity of surface circular footing on stiff-soft-stiff clays [J].Journal of Engineering Geology, 29(6): 1744-1751. doi: 10.13544/j.cnki.jeg.2021-0091
Citation: Wu Bing, Zheng Jingbin, Wang Dong. 2021. Study of bearing capacity of surface circular footing on stiff-soft-stiff clays [J].Journal of Engineering Geology, 29(6): 1744-1751. doi: 10.13544/j.cnki.jeg.2021-0091

“硬-软-硬”三层黏土上圆形基础的承载力分析

doi: 10.13544/j.cnki.jeg.2021-0091
基金项目: 

国家自然科学基金 51809247

国家自然科学基金 U1806230

山东省自然科学基金 ZR2018BEE043

详细信息
    作者简介:

    吴炳(1995-),男,硕士,主要从事海洋岩土工程研究工作. E-mail: wubing@stu.ouc.edu.cn

    通讯作者:

    郑敬宾(1989-),男,博士,副教授,主要从事海洋工程地质与岩土工程方面的科研与教学工作. E-mail: zhengjingbin@ouc.edu.cn

  • 中图分类号: P642;P67

STUDY OF BEARING CAPACITY OF SURFACE CIRCULAR FOOTING ON STIFF-SOFT-STIFF CLAYS

Funds: 

the National Natural Science Foundation of China 51809247

the National Natural Science Foundation of China U1806230

the Natural Science Foundation of Shandong ZR2018BEE043

  • 摘要: 海洋浅基础设计所遇地层条件通常由于基础大尺寸的特点而涉及多土层剖面,其中“硬-软-硬”三层黏土是最常见的地层条件之一。现行海洋浅基础设计常用的API和ISO规范尚无针对“硬-软-硬”黏土竖向承载力的计算方法。本文基于自升式平台基础设计规范推荐的“bottom-up”预测模型,假定“硬-软-硬”黏土上基础的承载力为“硬-软”黏土冲剪破坏产生的侧向摩阻力与“软-硬”黏土挤压破坏提供的承载力之和。通过有限元模拟分析,验证了“bottom-up”方法所假定破坏模型的合理性,但由于规范推荐的相关公式忽略了上覆土层对挤压破坏模式的影响,使其严重低估了“软-硬”黏土挤压破坏产生的承载力。基于变参数有限元分析结果,本文对挤压破坏承载力公式进行了修正,提出了“硬-软-硬”三层黏土上圆形基础竖向承载力的预测方法。
  • 图  1  多层土基础竖向承载力“bottom-up”预测模型(ISO,2016b)

    a. 第一步; b.第二步

    Figure  1.  "Bottom-up" predictive model for foundation bearing capacity on multi-layer soils(ISO, 2016b)

    图  2  有限元模型设置

    Figure  2.  Set-up of finite element numerical model

    图  3  有限元结果与理论解对比图(表 1组1)

    Figure  3.  Comparison of the FE and analytical results(Group 1, Table 1)

    图  4  “bottom-up”方法预测效果(表 1组2)

    Figure  4.  The performance of "bottom-up" method (Group 2, Table 1)

    图  5  软黏土夹层挤压破坏有限元分析模型

    Figure  5.  FE model for squeezing of interbedded soft clay

    图  6  有限元解析预测与“bottom-up”预测对比图(表 1组2)

    Figure  6.  Comparison of FE method and the current ISO method(Group 2, Table 1)

    图  7  d/D对挤压破坏模式的影响(表 1组3)

    Figure  7.  The influence of d/D on the squeezing mechanism(Group 3, Table 1)

    a. d/D=0; b. d/D=0.125; c. d/D=0.5

    图  8  修正系数公式效果(表 1组3)

    Figure  8.  The performance of the formula improved factor (Group 3, Table 1)

    图  9  su1/su2对挤压破坏模式的影响(表 1组4)

    Figure  9.  The influence of su1/su2 on the squeezing mechanism(Group 4, Table 1)

    a. su1/su2=1; b. su1/su2=2; c. su1/su2=4; d. su1/su2=8

    图  10  su1/su2Nc,23的影响(表 1组4)

    Figure  10.  The influence of su1/su2 on Nc, 23(Group 4, Table 1)

    图  11  改进方法预测效果(表 1组5)

    Figure  11.  The performance of the improved method (Group 5, Table 1)

    表  1  有限元分析参数汇总

    Table  1.   Summary of performed numerical analyses

    组号 t1/D t2/D d/D su1/su2 su3/su2 目的
    1 0.125~0.5 0 0.25 1 数值模型验证
    2 0.125,0.5 0.125 0 8 1.5~8 变参数分析
    3 0.125~0.5 0.125 0.125~0.5 1 4
    4 0.125 0.125 0.125 1~8 8
    5 0.125~0.5 0.1~0.29 0 3~8 3~8
    下载: 导出CSV

    表  2  单层土承载力系数比较

    Table  2.   Comparison of bearing capacity factors of single layer clay

    参考文献 解析方法 承载力系数Nc
    单层土 Cox et al.(1961) 理论解 6.05
    Salgado et al.(2004) 塑性上限 6.23
    塑性下限 5.86
    Merifield et al.(2006) 三维有限元 6.05
    Gourvenec et al.(2006) 有限元 5.96
    本研究 有限元 5.98
    下载: 导出CSV

    表  3  双层土承载力系数比较

    Table  3.   Comparison of bearing capacity factors of soft-over-stiff clays

    参考文献 解析方法 承载力系数Nc
    双层土 Meyerhof et al.(1953) 理论解 7.64
    Merifield et al.(2006) 三维有限元 7.95
    本研究 三维有限元(加密前:最小单元尺寸0.05D) 7.69
    三维有限元(加密后:最小单元尺寸0.025D) 7.44
    二维有限元 7.34
    下载: 导出CSV
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出版历程
  • 收稿日期:  2021-03-04
  • 修回日期:  2021-05-21
  • 刊出日期:  2021-12-25

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