Abstract Non-cohesive granular materials exhibit fabric-induced anisotropy of small-strain stiffness. The stiffness anisotropy is often measured using dynamic wave measurements in the laboratory. It is widely accepted that elastic wave velocities are influenced by stress state, while the role of particle shape in the wave velocity anisotropy, and thus the stiffness anisotropy, has not been fully understood. The difficulty arises partially from the incomplete understanding of particle-scale responses of granular materials. Considering 1D vertical compressoin with zero lateral strains (K0 condition) analogue to in-situ ground, this contribution performs wave propagation simulations using discrete element method and explores how particle shape and packing characteristics influence the anisotropy of elastic wave velocity. Sphere clumps with various aspect ratios are used. The orientation of the particle major axis is varied systematically by inhibiting particle rotation during dry-pluviation process. The simulation results reveal that the wave velocity anisotropy is largely affected by the combined effect of the particle aspect ratio and the orientation of particle major axis. Micromechanical analyses on assemblies of sphere clumps and ellipsoids shed light on the importance of the inter-particle contact stiffness, in addition to the particle aspect ratio and fabric, to determine the wave velocity anisotropy when non-spherical particles are used.

中文翻译：

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K条件下颗粒形状和织物各向异性对弹性波速度各向异性的影响

摘要 非粘性颗粒材料表现出织物诱导的小应变刚度各向异性。通常在实验室中使用动态波测量来测量刚度各向异性。人们普遍认为弹性波速受应力状态的影响，而粒子形状在波速各向异性以及刚度各向异性中的作用尚未完全清楚。困难部分源于对颗粒材料的颗粒尺度响应的不完全理解。考虑到与原位地面类似的具有零横向应变（K0 条件）的 1D 垂直压缩，该贡献使用离散元方法执行波传播模拟，并探索粒子形状和堆积特性如何影响弹性波速度的各向异性。使用具有各种纵横比的球团。通过在干降水过程中抑制颗粒旋转，颗粒长轴的方向发生了系统变化。模拟结果表明，波速各向异性在很大程度上受粒子纵横比和粒子长轴方向的综合影响。球团块和椭球体组件的微观力学分析阐明了粒子间接触刚度以及粒子纵横比和织物的重要性，以确定使用非球形粒子时的波速各向异性。模拟结果表明，波速各向异性在很大程度上受粒子纵横比和粒子长轴方向的综合影响。球团块和椭球体组件的微观力学分析阐明了粒子间接触刚度以及粒子纵横比和织物的重要性，以确定使用非球形粒子时的波速各向异性。模拟结果表明，波速各向异性在很大程度上受粒子纵横比和粒子长轴方向的综合影响。对球团块和椭球体组件的微观力学分析阐明了粒子间接触刚度的重要性，以及粒子纵横比和织物，以确定使用非球形粒子时的波速各向异性。