Recent advances in laboratory testing techniques enable accurate measurement of shear wave velocity in different planes for the determination of stiffness anisotropy of soils at very small strains. While most studies of elastic stiffness anisotropy have been conducted on sedimentary soils and clean sands, relatively little investigation into the anisotropic stiffness of decomposed materials has been reported. In this paper, a recent study of the degree of inherent stiffness anisotropy of natural completely decomposed tuff (CDT) and natural alluvium sampled from an excavation site in Hong Kong is discussed and reported. The shear moduli of CDT and alluvium at very small strains in the vertical and horizontal planes were determined by shear wave velocity measurements across specimen height and diameter using bender elements. The results are compared to the degree of inherent stiffness anisotropy of different materials. The effect of soil structure of natural material on stiffness anisotropy is highlighted.
展开▼
