饱和结构性黄土不排水柱孔扩张问题弹塑性解
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作者单位:

1.同济大学 岩土及地下工程教育部重点实验室,上海 200092;2.同济大学 土木工程学院,上海 200092

作者简介:

李镜培(1963—),男,教授,博士生导师,工学博士,主要研究方向为岩土力学及桩基础工程。 E-mail:lijp2773@tongji.edu.cn

通讯作者:

周 攀(1994—),男,博士生,主要研究方向为岩土力学及桩基础工程。 E-mail:zhoupan0201@tongji.edu.cn

中图分类号:

TU473

基金项目:

国家自然科学基金(41972274)


Elastic-plastic Solution for Undrained Expansion of Cylindrical Cavity in Saturated Structured Loess
Author:
Affiliation:

1.Key Laboratory of Geotechnical and Underground Engineering of the Ministry of Education, Tongji University,Shanghai 200092, China;2.College of Civil Engineering, Tongji University, Shanghai 200092, China

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    摘要:

    为导出饱和黄土中不排水柱孔扩张问题严格解,采用结构性黄土修正剑桥模型描述黄土力学特性。在弹性区采用小变形假设求解孔周土体应力与变形,同时将塑性区柱孔扩张边值问题转化为3个以应力分量为基本未知量的一阶非线性常微分方程求解问题。以弹塑性界面上应力分量作为初始条件求解控制方程,得到孔周塑性区应力分布,然后对径向平衡方程积分求得孔隙水压力。通过算例分析验证了该方法的正确性。结果表明:退化解与已有数值解完全吻合,并且黄土结构性对孔周应力、超静孔压以及弹塑性半径等影响显著。

    Abstract:

    To derive a rigorous solution for undrained expansion of cylindrical cavity, the modified Cam-clay model of structured loess was employed to describe the mechanical properties of loess. The small deformation assumption was used to solve the soil stress and deformation in the elastic zone around the cavity. Besides, the boundary value problem of cylindrical cavity expansion can be transformed into three first-order nonlinear ordinary differential equations with the stress component as the basic unknown quantity in the plastic region. The governing equation was solved by using the stress component on the elasto-plastic interface as the initial condition to obtain the stress distribution in the plastic zone around the cavity, then the pore water pressure was derived by integrating the radial equilibrium equation. The correctness of the method in this paper is verified by parameter analysis. The results show that the degenerate solution is completely consistent with the existing numerical solution, and the soil structure has a significant effect on the stress component, the specific volume, the excess pore water pressure, and elastic-plastic radius.

    图1 结构性黄土中的柱孔扩张力学模型Fig.1 Mechanical model of cylindrical cavity expansion in structured loess
    图2 归一化的扩孔压力与超静孔压随扩孔半径的变化Fig.2 Variation of normalized internal cavity pressure and excess pore pressure with cavity radius
    图3 不同超固结比结构性黄土的有效径向、切向与竖向应力分布(a/a0=2)Fig.3 Effective radial, tangential and vertical stress distributions for different over-consolidated structured loesses (a/a0=2)
    图4 不同超固结比结构性黄土的有效平均应力、偏应力与超静孔压分布(a/a0=2)Fig.4 Effective mean stress, deviator stress and excess pore pressure distributions for different over-consolidated structured loesses (a/a0=2)
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李镜培,周攀,李亮,谢峰,崔纪飞.饱和结构性黄土不排水柱孔扩张问题弹塑性解[J].同济大学学报(自然科学版),2021,49(2):163~172

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  • 收稿日期:2020-06-15
  • 在线发布日期: 2021-03-18
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