黄土沉积过程及微结构模型的非连续变形分析

张杰 李萍 李同录 张常亮 乔志甜 李强 沈伟

张杰, 李萍, 李同录, 等. 2021. 黄土沉积过程及微结构模型的非连续变形分析[J]. 工程地质学报, 29(4): 1199-1206. doi: 10.13544/j.cnki.jeg.2019-517
引用本文: 张杰, 李萍, 李同录, 等. 2021. 黄土沉积过程及微结构模型的非连续变形分析[J]. 工程地质学报, 29(4): 1199-1206. doi: 10.13544/j.cnki.jeg.2019-517
Zhang Jie, Li Ping, Li Tonglu, et al. 2021. Discontinuous deformation simulation of loess sedimentation process and microstructure model [J]. Journal of Engineering Geology, 29(4): 1199-1206. doi: 10.13544/j.cnki.jeg.2019-517
Citation: Zhang Jie, Li Ping, Li Tonglu, et al. 2021. Discontinuous deformation simulation of loess sedimentation process and microstructure model [J]. Journal of Engineering Geology, 29(4): 1199-1206. doi: 10.13544/j.cnki.jeg.2019-517

黄土沉积过程及微结构模型的非连续变形分析

doi: 10.13544/j.cnki.jeg.2019-517
基金项目: 

国家自然科学基金 41790442

国家自然科学基金 41877242

详细信息
    作者简介:

    张杰(1995-),男,硕士生,主要研究方向为土体微观力学. E-mail: 2018126088@chd.edu.cn

    通讯作者:

    张常亮(1979-),男,博士,副教授,主要从事地质灾害形成机理和防治,非饱和土及数值方法研究. E-mail: zcliang@chd.edu.cn

  • 中图分类号: P642.13+1

DISCONTINUOUS DEFORMATION SIMULATION OF LOESS SEDIMEN-TATION PROCESS AND MICROSTRUCTURE MODEL

Funds: 

the National Natural Science Foundation of China 41790442

the National Natural Science Foundation of China 41877242

  • 摘要: 黄土是一种具有特殊结构的多孔隙、弱胶结的松散沉积物,存在典型的微观架空结构,其力学行为是微观结构变形与破坏的宏观体现。从本质上揭示黄土的力学行为,需从黄土微结构出发,而黄土的物质组成和微结构特征受其特殊的风积成因所控制,基于此本文提出了一种模拟黄土沉积过程并构建其初始结构模型的方法。为了生成黄土沉积后所形成的微结构模型,并对其进行变形模拟,首先在确定黄土颗粒形态的基础上利用Monte Carlo法生成沉积前的黄土颗粒群,然后引入非连续变形分析方法(DDA)模拟颗粒的下落,该方法能够模拟颗粒下落过程中的相互碰撞及摩擦,由此建立与实际比较接近的黄土初始结构模型。从模型中可以识别出大、中、小3类孔隙结构和台阶(staircase)、重叠(stack)、点接触(point contact)、T型4种接触形式。对所生成的黄土结构模型进行不同压力下的压缩试验,选择不同部位的颗粒作出了径向分布函数,从微观角度说明了黄土在压缩过程中大孔隙和架空结构会首先被破坏。设计了与数值模拟相同条件下的物理模型试验,将两者试验结果进行对比,结果表明数值模拟与物理模型试验的e-lgp压缩曲线的趋势大致相同,表明所提出方法是可行的。该方法为进一步开展黄土力学行为的微观分析提供了基础。
  • 图  1  黄土颗粒的形状

    Figure  1.  The shape of loess particles

    图  2  黄土颗粒平均粒径频率分布

    Figure  2.  Frequency distribution of average particle size of loess

    图  3  利用Monte Carlo法生成的黄土颗粒群

    Figure  3.  Loess particle group generated by Monte Carlo method

    图  4  黄土沉积DDA初始数值模型

    Figure  4.  Initial numerical model of DDA in loess deposition

    图  5  初始黄土微观结构模型

    a. 台阶结构,b. 堆叠结构,c. 点接触结构,d. T型结构;①. 大孔隙,②. 中孔隙,③. 小孔隙

    Figure  5.  Initial loess microstructure model

    图  6  黄土中的T型接触结构

    Figure  6.  T-type contact structure in loess

    图  7  黄土的亚稳态结构

    Figure  7.  Metastable structure of loess

    图  8  各级荷载稳定后的模型

    a. 加载100 kPa;b. 加载200 kPa;c. 加载400 kPa;d. 加载800 kPa

    Figure  8.  Model after load stabilization at each level

    图  9  数值模型压缩曲线

    Figure  9.  Compression curve of the numerical model

    图  10  选定颗粒的径向分布函数

    Figure  10.  The radial distribution function of selected particle

    图  11  黄土沉积过程试验方案示意图

    Figure  11.  Schematic diagram of test scheme for loess deposition process

    图  12  数值模拟与实际试验对比

    Figure  12.  Comparison between numerical simulation and actual experiment

    表  1  模型物理力学参数

    Table  1.   Physical and mechanical parameters of model

    单元 密度/g·cm-3 弹性模量/GPa 泊松比 摩擦角/(°)
    土颗粒 2.65 30 0.25 40
    土样盒 9.00 100 0.10 0
    下载: 导出CSV
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出版历程
  • 收稿日期:  2019-11-28
  • 修回日期:  2020-03-11
  • 网络出版日期:  2021-09-03
  • 刊出日期:  2021-09-03

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