Recoverable Deformation of Cohesionless Soils

Herein is shown that available experimental data on the recoverable behavior of cohesionless soils may be fitted closely using constitutive relations corresponding to a special case of the first order theory of hypoelasticity. Four forms of first order isotropic constitutive law are first presented and conditions are determined under which each law is integrable to an elastic law. Constants for the isotropic hypoelastic law are then determined which fit available data for triaxial states of stress and it is shown that the resulting law is inelastic. Consideration is then given to fitting the data by means of an anisotropic first order incremental law. Integrability conditions for triaxial loading states are obtained and are shown to be satisfied by both isotropic and anisotropic laws. The integrated law for triaxial loading for the isotropic case is obtained and demonstrated by application to the anisotropic consolidation test. Tests are described to investigate the elastic character of the recoverable behavior.