Effect of Cyclic Rotation of Principal Stresses on Liquefaction Resistance of Sands

Abstract

Liquefaction susceptibility of loose sand subjected to different magnitudes of principal stress rotation under different initial stress states is evaluated. Hollow cylinder torsional shear tests were carried out on water pluviated Fraser River sand specimens hydrostatically consolidated to two different effective confining stresses. Cyclic loading was applied with constant amplitude cyclic deviator stress, but along stress paths which impose different magnitudes of principal stress rotation. Both axisymmetric and approximately plane strain loading conditions were simulated by fixing the intermediate principal stress parameter, bσ= (σ2-σ3)/(σ1-σ3) at 0 or 0.4 respectively. Tests results show that weakest cyclic resistance is manifested when the principal stress direction is cyclically rotated between ±45° with respect to the axis of deposition. Irrespective of the different initial effective confining stress and intermediate principal stress parameter, the combination of high shear stress on the horizontal plane and the orientation of the plane of maximum shear stress with the bedding plane are found to be responsible for the weakest cyclic resistance.