Abstract: A series of drained shear tests are carried out on saturated sand samples using hollow cylinder apparatus. Four groups of stress paths are considered to study the deformation characteristics of the sand under drained shearing condition, with emphasis on analyzing the variations of the directions of the principal stress increment and strain increment of the sand along various stress paths. The considered stress paths include fixed principal stress directions with increasing of deviatoric stress ratio (shear loading with fixed principal stress directions), principal stress rotation with constant deviatoric stress ratio (pure principal stress rotation), simultaneous increase in deviatoric stress ratio and principal stress rotation; multilinear simultaneous increase in deviatoric stress ratio and principal stress rotation. The experimental results indicate that the major principal stress increment direction varies between 45° and 135° under the pure rotation of principal stress axes. The major principal strain increment direction moves gradually towards the direction of principal stress. Deformations accumulate under simultaneous increase in stress ratio and principal stress rotation. The direction of principal strain increment coincides with stress increment when 45°, whereas the direction of principal strain increment deviates from stress increment when 45°. Deformation is practically stress-path independent and the strain response under subsequent principal stress rotation is shown to be independent of the previous loading history, if the final stress state is within the approximate bounds of 0.75 and 45°.

Key words: hollow cylinder apparatus, principal stress rotation, saturated sand, stress paths, deformation behavior