This paper presents a multiscale experimental study integrated with numerical simulations examining the mechanics of polydisperse granular mixtures composed of coarse‐grained particles mixed with varying percentages of fines. The study includes macroscale wave propagation tests using bender elements on isotopically compressed granular samples to investigate the stiffness variation with changes in size ratio (SR) and fines content (FC). Empirical equations were developed to predict stiffness based on the experimental data, using the concept of equivalent void ratio to represent the influence of void ratio on stiffness. A newly introduced parameter called size disparity indicator was used to consider the coupled effects of size disparity and fines content on stiffness. Microscale assessment of the individual contacting grains revealed that stiffness (at grain scale) is affected by changes in grain size, even when the SR is less than 6, however, the experimental observations of the shear modulus behavior from the macroscale test results reveal minimal effect of FC. Furthermore, numerical simulations using the discrete element method were conducted on the polydisperse granular mixtures to demonstrate the coupled effect of SR and FC on the structural matrix formation, thereby influencing the force transfer among contacts resulting in varying stiffness behavior. Our findings provide valuable insights into the behavior of polydisperse granular mixtures in engineering applications.

中文翻译：

---

多分散颗粒材料的多尺度力学：从微观尺度和波传播实验到 DEM 分析


本文提出了一项与数值模拟相结合的多尺度实验研究，检查由粗粒颗粒与不同比例的细粉混合组成的多分散颗粒混合物的力学。该研究包括使用弯曲元件对同位素压缩颗粒样品进行宏观波传播测试，以研究刚度随尺寸比 (SR) 和细粉含量 (FC) 变化的变化。根据实验数据建立了经验方程来预测刚度，使用等效孔隙比的概念来表示孔隙比对刚度的影响。新引入的称为尺寸差异指标的参数用于考虑尺寸差异和细粉含量对刚度的耦合影响。对各个接触晶粒的微观评估表明，即使 SR 小于 6，刚度（晶粒尺度）也会受到晶粒尺寸变化的影响，但是，宏观测试结果对剪切模量行为的实验观察显示影响很小的FC。此外，使用离散元方法对多分散颗粒混合物进行数值模拟，以证明 SR 和 FC 对结构基体形成的耦合效应，从而影响接触之间的力传递，从而导致不同的刚度行为。我们的研究结果为多分散颗粒混合物在工程应用中的行为提供了宝贵的见解。