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 G 0 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 (D 50 ).
The behavior of a sandy soil in laboratory tests is highly influenced by the sedimentation technique. In this study, a calcareous sand from the reclamation site in Persian Gulf is used as the material to reconstruct laboratory scale samples with the air and water pluviation, moist and dry tamping and dry funnel deposition methods. The microstructure of these calcareous sand samples, including the homogeneity and the spatial consistency of the fabric anisotropy, is examined using X-ray tomography. It is shown that the sample preparation method introduces distinct differences in the sample uniformity and the spatial fabric anisotropy. The sample density varies along the sample height and is highly affected by the boundary effect. The fabric anisotropy is proved to have spatial consistency except for the sample made by the water pluviation method. In the water pluviation sample, the boundary effect on the fabric anisotropy is significant, which is explained by the grain-water interaction during the sedimentation.
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