A CONSTITUTIVE EQUATION OF SAND AS ANISOTROPIC ELASTO-PLASTIC BODY

A sand is a complicated material that is associated with dilatancy by loading and is also largely influenced by stress histories. In order to represent the characteristics of sand, subsequent anisotropy, which is induced by dilatancy accompanying plastic deformation, is evaluated on the basis of the results obtained from simple laboratory tests under axisymmetric stress conditions. Furthermore, an elasto-plastic stress-strain relation for sand is derived from considering a sand as a strain hardening material not only for shear but also for compression and adopting stress-dilatancy relation. From comparisons of the calculated results with the strains measured in the stress path tests with complex stress histories, it is shown that the proposed equation may be useful in prediction of the stress-strain behaviour of sands.