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DEM simulations of the small strain stiffness of granular soils: effect of stress ratio

机译：粒状土小应变刚度的DEM模拟：应力比的影响

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摘要

DEM (discrete element method) simulations are carried out to evaluate the small strain stiffness (i.e. Young's modulus and shear modulus) of a granular random pack-ing with focus on the effect of stress ratio (SR). The results show that the Young's modulus in a given direction gener-ally depends on the stress component in that direction. The Young's modulus normalized by the related stress compo-nent remains nearly constant when SR is less than a thresh-old value SR_(th). When SR is larger than SR_(th), the normalized Young's modulus decreases, particularly in the minor princi-ple stress direction. Moreover, the Young's modulus during unloading is always smaller than the one during loading at the same stress state, which indicates that the microstruc-ture of the specimen has been modified by the historical shearing process. The shear modulus mainly depends on the mean effective stress and shows similar evolution trend as the Young's modulus. This study finds that the macroscopic stiffness of the specimen is closely related to the evolutions of particle contact number and contact force during shear-ing. When SR is less than SR_(th), the specimen only adjusts the distribution of contact forces to resist the external load, without any apparent change of contact number. When SR is larger than SR_(th), however, the specimen has to adjust both contact number and contact forces to resist the exter-nal load. The study also illustrates that there is a good rela-tionship between the macroscopic stiffness anisotropy and fabric anisotropy, and therefore the stiffness anisotropy may be used as an indicator of fabric anisotropy.
机译：进行DEM（离散元法）模拟以评估颗粒状随机堆积的小应变刚度（即杨氏模量和剪切模量），重点是应力比（SR）的影响。结果表明，给定方向上的杨氏模量通常取决于该方向上的应力分量。当SR小于阈值SR_（th）时，由相关应力分量归一化的杨氏模量几乎保持恒定。当SR大于SR_（th）时，归一化的杨氏模量降低，尤其是在次要原理应力方向上。此外，在相同应力状态下，卸载过程中的杨氏模量始终小于加载过程中的杨氏模量，这表明样品的微观结构已被历史剪切过程所改变。剪切模量主要取决于平均有效应力，并且显示出与杨氏模量相似的演变趋势。这项研究发现，试样的宏观刚度与剪切过程中颗粒接触数和接触力的变化密切相关。当SR小于SR_th时，样品仅调整接触力的分布以抵抗外部载荷，而接触数没有任何明显变化。但是，当SR大于SR_th时，样品必须同时调整接触数和接触力以抵抗外部载荷。研究还表明，宏观刚度各向异性和织物各向异性之间存在良好的关系，因此刚度各向异性可以用作织物各向异性的指标。

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  • 来源
    《Granular matter》 |2013年第3期|287-298|共12页
  • 作者

    Xiaoqiang Gu; Jun Yang; Maosong Huang;

  • 作者单位

    Key Laboratory of Geotechnical and Underground Engineering of the Ministry of Education, Tongji University, Shanghai 200092, China;

    Department of Civil Engineering, The University of Hong Kong, Pokfulam, Hong Kong, China;

    Key Laboratory of Geotechnical and Underground Engineering of the Ministry of Education, Tongji University, Shanghai 200092, China;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

    Discrete element; Small strain stiffness; Young's modulus; Shear modulus; Stress ratio; Anisotropy;

    机译：离散元素;应变刚度小;杨氏模量剪切模量;应力比各向异性;

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