Sands exhibit a directional diversity in shear modulus at small strains, reflecting the anisotropic stiffness behaviour in the structure. In this paper, sample preparation method, particle shape and particle size are considered as parameters to produce samples with various initial fabric. Five preparation methods, namely, air and water pluviation, dry and moist tamping and dry funnel deposition are used to reconstitute the samples. The stiffness anisotropy of calcareous sand and Mol silica sand is quantified by the small-strain modulus G₀ measured in horizontal and vertical planes with the bender element technique in triaxial tests. Test results show that calcareous sands behave as an elastic homogeneous continuum material at small strains. Calcareous samples prepared by the air pluviation method possess the highest anisotropic ratios. The lowest stiffness anisotropy exists in the samples prepared by moist tamping and dry funnel deposition methods. Compared with the anisotropic ratios of the air pluviation samples from the literature, the notably higher values for the calcareous sand in this study are attributed to the lower sphericity. In addition, less prominent stiffness anisotropy is found in calcareous sands with smaller particle sizes (D₅₀).

中文翻译：

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样品制备，颗粒特性和梯度对钙质砂土各向异性小应变刚度的影响

在小应变下，砂表现出剪切模量的方向多样性，反映了结构中的各向异性刚度行为。在本文中，样品制备方法，颗粒形状和粒径被视为生产具有各种初始织物的样品的参数。五种制备方法，即空气和水的富集，干湿捣固和干漏斗沉积，用于重构样品。通过小应变模量G ₀量化钙质砂和硅质硅砂的刚度各向异性在三轴测试中使用弯曲元件技术在水平和垂直平面上进行测量。试验结果表明，在小应变下，钙质砂表现为弹性均质连续体材料。通过空气富集法制备的钙质样品具有最高的各向异性比率。通过湿捣固和干漏斗沉积法制备的样品中存在最低的刚度各向异性。与文献中的空气富集样品的各向异性比率相比，本研究中钙质砂的明显较高的值归因于较低的球形度。另外，在粒径较小的钙质砂中发现较小的刚度各向异性（D ₅₀）。