DEM analysis on the stress wave response of spherical particle assemblies under triaxial compression
DEM analysis on the stress wave response of spherical particle assemblies under triaxial compression
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DOI：
10.1016/j.compgeo.2021.104043
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发表时间：
2021-05
影响因子：
5.3
通讯作者：
Yang Li;M. Otsubo;R. Kuwano
中科院分区：
文献类型：
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作者：
Yang Li;M. Otsubo;R. Kuwano
由于复杂的颗粒尺度相互作用，特别是在加载过程中，理解无凝聚力颗粒集合体的应力波响应包括压缩和剪切波速度（Vp和Vs）是具有挑战性的。本文采用离散元法对球形颗粒的三轴压缩实验进行了数值模拟。四个样品各向同性限制在不同的初始堆积密度，然后单调剪切到临界状态。小振幅波的传播模拟过程中进行剪切沿着加载轴。结果表明，Vp主要受垂直方向的最大主应力和配位数的影响，而受几何平均应力和平均配位数的影响较大。波速比（Vp/Vs）与组构各向异性有很好的相关性，呈线性关系。这使得能够从宏观波速值预测组构的微观变化。此外，应力水平和波速之间的材料特定的关系被发现在临界状态下具有独特的织物各向异性，独立于初始包装。VS在各向同性状态下被发现总是大于在临界状态下的等效应力水平。
It is challenging to understand the stress wave response of cohesionless particle assemblies including compression and shear wave velocities (V p and V s) due to complicated particle-scale interactions particularly during a loading process. This contribution adopts the discrete element method to simulate triaxial compression experiments using spherical particles. Four samples are isotropically confined at various initial packing densities and then sheared monotonically up to the critical state. Small-amplitude wave propagation simulation is performed during shearing along the axis of loading. The results reveal that V p is affected by the major principal stress and the coordination number contributing to the vertical direction rather than horizontal direction, while V s is more influenced by the geometric mean stress and the mean coordination number. The wave velocity ratio (V p/V s) is well correlated with the fabric anisotropy, having a linear relationship. This enables prediction of microscopic change in fabric from macroscopic wave velocity values. Besides, a material-specific relationship between stress levels and wave velocities is found at the critical state with a unique fabric anisotropy, independent of initial packing. V s in the isotropic state is found to be always larger that at the critical state under an equivalent stress level.