华南理工大学学报(自然科学版) ›› 2022, Vol. 50 ›› Issue (11): 141-154.doi: 10.12141/j.issn.1000-565X.210747

所属专题: 2022年土木建筑工程

• 土木建筑工程 • 上一篇    

偏心率对颗粒介质次生各向异性的影响

周小文 许衍彬 赵仕威 陈昊 张昌辉   

  1. 华南理工大学 亚热带建筑科学国家重点实验室∥华南岩土研究院,广东 广州 510640
  • 收稿日期:2021-11-29 出版日期:2022-11-25 发布日期:2022-03-11
  • 通信作者: 赵仕威(1991-),男,博士,副教授,主要从事颗粒力学理论与数值方法研究。 E-mail:swzhao@scut.edu.cn
  • 作者简介:周小文(1965-),男,博士,教授,主要从事土的基本性质及颗粒力学理论研究.E-mail:xwzhou@scut.edu.cn.
  • 基金资助:
    国家自然科学基金资助项目(51909095);广东省自然科学基金资助项目(2020A1515011525);华南理工大学中央高校基本科研业务费专项基金资助项目(D2192710)

Influence of Eccentricity on Induced Anisotropy of Granular Media

ZHOU Xiaowen XU Yanbin ZHAO Shiwei CHEN Hao ZHANG  Changhui    

  1. State Key Laboratory of Subtropical Building Science// South China Institute of Geotechnical Engineering,South China University of Technology,Guangzhou 510640,Guangdong,China
  • Received:2021-11-29 Online:2022-11-25 Published:2022-03-11
  • Contact: 赵仕威(1991-),男,博士,副教授,主要从事颗粒力学理论与数值方法研究。 E-mail:swzhao@scut.edu.cn
  • About author:周小文(1965-),男,博士,教授,主要从事土的基本性质及颗粒力学理论研究.E-mail:xwzhou@scut.edu.cn.
  • Supported by:
    the National Natural Science Foundation of China(51909095);the Natural Science Foundation of Guangdong Province(2020A1515011525)

摘要:

颗粒介质的细观组构各向异性与宏观力学特性有密切的跨尺度联系,而颗粒形态特征对其组构各向异性的演化又起着重要的作用。除了颗粒的球度、棱角度、粗糙度以外,作者关注到颗粒形态特征中的偏心也是一个重要的影响因素,而至今很少有关于它的研究。本文采用所在团队自编的非球离散元程序SudoDEM构建了基于扩展超级椭球的偏心颗粒模型,开展了不同偏心颗粒的真三轴剪切模拟,探究偏心率对颗粒介质次生各向异性的影响,进而揭示颗粒介质宏观力学响应的细观机理。结果表明:细观组构各向异性随偏心率增大呈不同程度发展,共同承担着宏观抗剪强度的提升,同时配位数更大,滑动接触比例更高,接触力网格不均匀性也愈明显,这主要因为颗粒偏心增强了颗粒间的互锁咬合;法向接触力在次生各向异性中权重最大,法向支向量各向异性可忽略不计,切向接触力与切向支向量的各向异性受颗粒偏心影响较为敏感,在偏心颗粒试样中对强度贡献不可忽略;因偏心率而提高的弱接触、滑动接触比例间接导致了法向接触力各向异性向切向接触力各向异性转化。

关键词: 偏心率, 颗粒介质, 细观组构, 各向异性, SudoDEM, 偏心颗粒离散元模型

Abstract:

There is a close cross-scale relationship between fabric anisotropy of granular media and the macro-mechanical properties, and particle shape plays a significant role in the evolution of the fabric anisotropy. In addition to sphericity, angularity and roughness of particles, the authors found that the eccentricity in the particle morphology is also an important factor, and there were few studies on it so far. So in this paper, the open source aspheric DEM program SudoDEM was used to model eccentric particles based on poly-superellipsoids. A series of true triaxial simulations with different eccentricities were carried out, and the effects of eccentricity on the induced anisotropy of granular media were explored. The results show that the fabric anisotropy develops to varying degrees with the increase of eccentricity, leading to the development of macroscopic shear resistance of granular media. Meanwhile, the coordination number is larger, the proportion of sliding contacts is higher, and the grid inhomogeneity of the contact force is more obvious. This is mainly because the particle eccentricity enhances the interlocking between particles. Normal contact force has the largest weight in the induced anisotropy, while the normal branch vector remains basically isotropic. Anisotropy of tangential contact force and tangential branch vector are rather sensitive to the eccentricity, indicating that contribution of them to fabric anisotropy cannot be ignored. The increased weak contact and sliding contact proportions caused by the increased eccentricity also indirectly lead to transformation between the normal contact force anisotropy and tangential contact force anisotropy.

Key words: eccentricity, particle media, fabric, anisotropy, SudoDEM, eccentric particle model

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