A NEW DOUBLE HARDENING MODEL FOR SOILS UNDER CYCLIC LOADING. NUMERICAL MODELS IN GOEMECHANICS. NUMOG III. PROCEEDINGS OF THE 3RD INTERNATIONAL SYMPOSIUM HELD AT NIAGARA FALLS, CANADA, 8-11 MAY 1989

In this paper, a cyclic elastoplastic constitutive equation using the principle of "bounding surface" is presented in order to describe the behaviour of granular soils under non-monotonic loading. The formulation uses two yield surfaces governed by the evolution of hardening parameters. The most important part of the plastic strain is described by means of a shear yield surface and a non-associative flow rule so that dilatancy effects are well taken into account. A new three dimensional yield criterion is also developed on the basis of lade's criterion and recent experimental evidence. The other part of the plastic strain is produced by a volumetric yield surface and an associated flow rule. The bounding surface theory coupled with an adequate interpolation rule for the hardening plastic modulii is incorporated in the equation so that qualitative and quantitative effects of cyclic loading are well described. For the covering abstract of this conference see IRRD 824029.