Effects of initial fabric and shearing direction on cyclic deformation characteristics of sand

Abstract

The paper presents a study of the effects of initial fabric and shearing direction on cyclic deformation characteristics such as stress-strain response, shear modulus and damping ratio from drained static cyclic tests on medium dense Toyoura sand using hollow cylinder apparatus. The apparatus allows independent control of stress components, σz, σ θ, σr and τzθ, and accurate measurement of strain components, εz, ε θ, εr and γzθ, over a wide range of strains from 10-3% to 10%. Three methods of sample preparation, air pluviation, water pluviation and dry rodding, were employed to produce different initial fabrics. Samples were sheared cyclically in p′-constant plane along the direction of major principal stress 0° (90°), 22.5° (-67.5°) and 45° (-45°) relative to the direction of deposition. Anisotropic behaviour was observed in stress-strain response and the secant shear moduli defined separately for each direction of major principal stress. However, the equivalent shear modulus was found to be little affected by the direction of the major principal stress. In addition, the effect of initial fabrics was not significant. The same was found for the hysteretic damping ratio.