Modelling of Hardening and Degradation Behavior of Clays and Sands During Cyclic Loadings

It is demonstrated that the stress-strain response in both undrained and drained cyclic loading conditions is of the hardening type until the shear strain is smaller than the so called volumetric threshold. On the contrary, beyond this limit, degradation phenomena occur. In this paper, the possibility of modelling the hardening and degradation behaviour of clays and sands with a simple law is examined. In particular, the case of one-dimensional loading is considered. Experimental data on reconstituted Toyoura sand specimens and undisturbed specimens of three Italian clays (Pisa, Augusta and Catania) have been used.