The geo-mechanical behavior of granular materials rigorously depends on their initial packing density, stress level and particle size distribution. Moreover, the behavior of binary granular soil is affected by the quality and quantity of their small particles named the fines content (FC). The contribution mechanism of the FC to the load-bearing structure of the soil at various particle sizes, stress levels and densities is still pending. The present study aimed to use a micromechanical approach to simulate the behavior of binary mixtures with particle size ratios (α) of 2.5 to 7.1 and study the effect of stress level and initial packing density on the stress–strain behavior using discrete element method (DEM). Accordingly, the effect of FC on the internal friction angle, anisotropy parameters, coordination number and coarse–fine (C–F) contacts have been studied. The results indicate that the variation in peak shear strength versus FC is bell-shaped with a minimum for FC of 30% to 40% and this is independent of initial packing density and stress level, but depending on the value of α. The greater particle size ratios (α = 7.1) increase the tendency of fines particles to rotate during biaxial testing, reduced the shear strength in comparison with samples with small particle size ratios (α = 2.5). Exceeding the threshold FC (30–40%) led to formation of stronger force chains among the fines and increased the role of FC on the peak shear strength.

中文翻译：

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初始堆积密度，应力水平和粒径比对二元颗粒材料性能的影响：一种微机械方法

粒状材料的地质力学行为严格取决于其初始堆积密度，应力水平和粒径分布。此外，二元颗粒状土壤的行为受其细颗粒的质量和数量（称为细粒含量（FC））的影响。在各种粒径，应力水平和密度下，FC对土壤承重结构的贡献机制仍未确定。本研究旨在使用微机械方法来模拟粒度比（α）为2.5至7.1的二元混合物的行为，并使用离散元方法（DEM）研究应力水平和初始堆积密度对应力-应变行为的影响。 ）。因此，FC对内摩擦角，各向异性参数，已经研究了配位数和粗-精（CF）接触。结果表明，峰值剪切强度与FC的变化呈钟形，FC的最小值为30％至40％，这与初始填充密度和应力水平无关，但取决于α值。与具有较小粒径比（α= 2.5）的样品相比，较大的粒径比（α= 7.1）增加了细颗粒在双轴测试过程中旋转的趋势，降低了剪切强度。超过阈值FC（30–40％）会导致细粉之间形成更强的力链，并增加FC对峰值剪切强度的作用。结果表明，峰值剪切强度与FC的变化呈钟形，FC的最小值为30％至40％，这与初始填充密度和应力水平无关，但取决于α值。与具有较小粒径比（α= 2.5）的样品相比，较大的粒径比（α= 7.1）增加了细颗粒在双轴测试过程中旋转的趋势，降低了剪切强度。超过阈值FC（30–40％）会导致细粉之间形成更强的力链，并增加FC对峰值剪切强度的作用。结果表明，峰值剪切强度与FC的变化呈钟形，FC的最小值为30％至40％，这与初始填充密度和应力水平无关，但取决于α值。与具有较小粒径比（α= 2.5）的样品相比，较大的粒径比（α= 7.1）增加了细粉颗粒在双轴测试过程中旋转的趋势，降低了剪切强度。超过阈值FC（30–40％）会导致细粉之间形成更强的力链，并增加FC对峰值剪切强度的作用。