Study of anisotropic shear strength of granular materials using DEM simulation
Study of anisotropic shear strength of granular materials using DEM simulation
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DOI：
10.1002/nag.945
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发表时间：
2011-07
影响因子：
4
通讯作者：
P. Fu;Y. Dafalias
中科院分区：
文献类型：
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作者：
P. Fu;Y. Dafalias
本文研究了具有固有组构各向异性的颗粒材料的抗剪强度。以前的大多数研究都是在主应力空间描述这些材料的强度，而层理平面相对于主应力方向的取向被用作固有组构的参考几何描述符。本研究发现，对于同样的目的，用层面相对于剪切面的倾角来代替，在理论上更方便，在实际中更有用。采用椭圆形颗粒离散元模型，模拟了不同加载方向下的顺层直剪试验和双向压缩试验。数值模拟成功地捕捉到了文献中报道的天然砂的关键力学行为。基于直接剪切模拟结果，确定了剪切破坏准则作为倾角的函数，并成功地用于预测双轴压缩模拟结果。双轴压缩变形和应变局部化模拟的微观结构检验发现，所提出的剪切破坏准则可以合理地预测初始破坏面的方位。研究还发现，在较大应变水平下，与初始破坏面方向共轭的剪切带可以发展并控制试件的变形。考虑到双轴压缩试验设备的可用性和历史数据，提出了两种由双轴压缩试验结果反算倾角相关抗剪强度的方法，并用DEM模拟结果进行了验证。版权所有©2010 John Wiley&Sons，Ltd.
This paper investigates shear strength of granular materials with inherent fabric anisotropy. Most previous studies have described strength of these materials in the principal stress space, and the orientation of the bedding plane with respect to the principal stress directions was used as the reference geometrical descriptor of inherent fabric. The present study has found that it is theoretically more convenient and practically more useful to use instead the inclination angle of the bedding plane with respect to the shear plane for the same purpose. Direct shear tests and biaxial compression tests with different loading directions with respect to the bedding planes were simulated with discrete element method (DEM) models consisting of ellipse‐shaped particles. Key mechanical behaviors of natural sands reported in the literature were successfully captured in the numerical simulation. A shear failure criterion was determined as a function of the inclination angle based on the direct shear simulation results, and was used to successfully predict the results of the biaxial compression simulations. Microstructural inspection of deformation and strain localization of the biaxial compression simulations found that the proposed shear failure criterion can reasonably predict the orientations of the initial failure planes. It was also discovered that shear bands in directions conjugate to the initial failure plane orientations can develop and dominate specimen deformation at larger strain levels. Considering the availability of biaxial compression test equipment and historical data, two methods for back‐calculating inclination angle‐dependent shear strength from biaxial compression results were proposed, and validated using DEM simulation results. Copyright © 2010 John Wiley & Sons, Ltd.