Liquefaction of sand under Bi-directional cyclic loading

Abstract

A laboratory study is presented of liquefaction behavior of saturated loose sand subjected to bi-directional cyclic loading under isotropic consolidated conditions using the soil static and dynamic universal triaxial and torsional shear apparatus, which can apply axial pressure W and torque MT individually. Tests were performed following the stress path that is controlled by shape of ellipse in terms of axial component σd/2 and torsional component τ . In this type of loading pattern the progressive rotation of orientation of principal stress axe and the unequal transverse and longitudinal cyclic components can be realized for simulating the complex stress condition induced by wave or earth embankments. For equivalent ratio of σd/2 to τ the cyclic loading resistance decreases with the increasing area bounded by the elliptical stress path. And for the same area of the elliptical stress path, the sample exhibits the highest resistance to liquefaction when the ratio of σd/2 to τ reaches a critical value which equals to 0.6 - 0.75. The deformation behavior of sand is also considerably associated with the proportion of σd/2 to τ. © 2008 Science Press Beijing and Springer-Verlag GmbH Berlin Heidelberg Geotechnical Engineering for Disaster Mitigation and Rehabilitation.