Investigation of dynamic properties of carbonate/calcareous soils is important in earthquake and offshore engineering as these soils are commonly encountered in large-scale projects related with energy geomechanics and land reclamation. In this study, the stiffness and stiffness anisotropy of two types of calcareous sands (CS) from the Western Australia and the Philippines were examined using bender elements configured in different directions in stress path setups. Stiffness measurements were taken on specimens subjected to constant p′ compression/extension and biaxial stress paths and additional tests were performed on three types of silica sands with different geological origins and particle shapes, which were used as benchmark materials in the study. Compared with the three brands of silica sands, the stiffness of the CS was found to be more significantly influenced by anisotropic loading; an important observation of the experimental results was that stress anisotropy had different weighted influences on the stiffness in different directions, thus influencing stiffness anisotropy. Comparisons were made between the specimens subjected to complex loading paths, and respected model parameters as suggested from published expressions in the literature. These comparisons further highlighted that calcareous soils have different responses in terms of stiffness, stiffness anisotropy and loading history, compared with that of silica-based sands.

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Keywords: Calcareous soils, Dynamic properties, Shear stiffness, Stress anisotropy, Stress history