岩土力学 ›› 2023, Vol. 44 ›› Issue (5): 1375-1384.doi: 10.16285/j.rsm.2022.0885

• 基础理论与实验研究 • 上一篇    下一篇

砂土地基中桩顶竖向-水平加载路径下柔性单桩水平承载力分析

江杰1, 2, 3，付臣志2，柴文成2，欧孝夺1, 2, 3   

  1. 1. 广西大学 工程防灾与结构安全教育部重点实验室，广西 南宁 530004； 2. 广西大学 土木建筑工程学院，广西 南宁 530004；3. 广西大学 防灾减灾与工程安全重点实验室，广西 南宁 530004
  • 收稿日期:2022-06-13 接受日期:2022-09-28 出版日期:2023-05-09 发布日期:2023-04-30
  • 作者简介:江杰，男，1979年生，博士后，研究员，主要从事桩基工程理论与应用研究。
  • 基金资助:
    国家自然科学基金项目（No. 52068004）；广西大学学科交叉科研项目（No. 2022JCB012）；广西重点研发计划项目（No. AB19245018）.

Analysis of lateral bearing capacity of flexible single pile under vertical-horizontal loading path in sand foundation

JIANG Jie1, 2, 3, FU Chen-zhi2, CHAI Wen-cheng2, OU Xiao-duo1, 2, 3   

  1. 1. Key Laboratory of Disaster Prevention and Structural Safety of Ministry of Education, Guangxi University, Nanning, Guangxi 530004, China; 2. School of Civil Engineering and Architecture, Guangxi University, Nanning, Guangxi 530004, China; 3. Guangxi Key Laboratory of Disaster Prevention and Engineering Safety, Guangxi University, Nanning, Guangxi 530004, China
  • Received:2022-06-13 Accepted:2022-09-28 Online:2023-05-09 Published:2023-04-30
  • Supported by:
    This work was supported by the National Natural Science Foundation of China (52068004), the Interdisciplinary Scientific Research Foundation of Guangxi University (2022JCB012) and the Key Research Projects of Guangxi (AB19245018).

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摘要： 砂土地基中桩顶竖向-水平加载路径下单桩水平承载理论研究较少，且鲜有考虑预先施加的竖向荷载对土抗力p与桩身水平位移y曲线的影响。鉴于此，考虑桩顶预先施加的竖向力对桩周土体产生挤密作用，从而对双曲线型p-y曲线的极限土抗力进行修正。采用余弦函数表征被动侧径向土压力分布，构建了被动侧最大径向土压力与总土抗力的关系式，推导了被动侧的侧阻抗力矩解析表达式。考虑被动侧摩阻力与竖直方向存在夹角 对由摩阻力引起的桩身轴力变化量进行修正，给出了修正计算公式。建立了同时考虑修正的 p-y 曲线、桩身自重和被动侧摩阻力引起的轴力变化量、二阶效应（即 p-Δ效应）以及侧阻抗力矩的桩身挠曲微分方程，通过 MATLAB 编程求得其数值解。将计算结果与已有模拟和试验结果进行比较，验证了该方法的正确性。在此基础上，探讨了预先施加的竖向力大小对单桩水平承载性能的影响。计算结果表明：推导的桩身轴力变化量计算公式能更准确地表征被动侧摩阻力对桩身轴力的影响，且可用于大变形条件；预先施加的竖向力可以增大柔性单桩的水平承载力，随着预先施加的竖向力的增大，增强效果逐渐减弱。

关键词: 砂土地基, 柔性单桩, 竖向-水平加载路径, 水平承载力, 数值解

Abstract: There are few theoretical studies on lateral bearing capacity of flexible single pile under vertical-horizontal loading path in sand foundation and the influence of pre-applied vertical load on p-y curve is rarely considered. In view of this, the ultimate soil resistance of hyperbolic p-y curve was modified accounting for compacting effect of the sandy soil around the pile under the vertical force applied in advance. Cosine function was used to characterize the distribution of radial earth pressure on the passive side. The relationship between the maximum radial earth pressure on the passive side and the total soil resistance was proposed, and the analytical expression of the shaft resisting moment on the passive side was derived. Taking an included angle β  between the direction of friction resistance and the vertical direction into account, the variation of pile axial force induced by friction resistance was corrected and its computational formula was obtained. The differential equation of pile deflection was established considering the modified p-y curve, the variation of axial force caused by pile dead weight and friction resistance, the P-Δ effect and the shaft resisting moment. The numerical solution was obtained by MATLAB program. The correctness of the proposed method was verified by comparing the calculated results with the existing simulations and measurements. On this basis, the influence of vertical force applied in advance on lateral bearing capacity of single pile was discussed. The results show that the computational formula of the variation of pile axial force deduced in this paper can more accurately describe the influence of friction resistance on pile axial force and can be used for large deformation conditions. The vertical force applied in advance can enhance the lateral bearing capacity of flexible single pile. The enhancement gradually decreases with the increase of the vertical force applied in advance.

Key words: sand foundation, flexible single pile, vertical-horizontal loading path, lateral bearing capacity, numerical solution

中图分类号: TU 473
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