The induced anisotropy of Leighton Buzzard sand

The induced anisotropy of Leighton Buzzard sand under generalised stress conditions was investigated using a new, automated hollow cylinder apparatus. Identical test-specimens of sand were isotropically consolidated followed by anisotropic consolidation, involving different magnitudes of the three principal stresses and rotation of the major principal stress. Details of the stress paths followed are presented. The induced anisotropy of the test-specimens was analysed by exploring the relationships between the deviator strain and the principal and volumetric strains. Analysis of the experimental data indicated that a predominately linear relationship exists between the deviator strain and the principal and volumetric strains for all principal stress combinations and rotation of the major principal stress. The magnitude of the intermediate principal stress was found to have a profound influence on the strain responses. When the intermediate and minor principal stresses were maintained equal, the magnitudes of all strain components were found to be proportional to the rotation of the major principal stress. However, the latter relationship disappeared and the magnitudes of the resultant strains were smaller once the intermediate principal stress increased relative to the minor principal stress.