Modelling small strain behaviors of overconsolidated clays

Firstly, a new elastic framework, called the elastic hysteretic stress-strain relationship, is established to evaluate the stiffness degradation at small strains and the hysteresis loop generated under cyclic loading condition. Secondly, in order to reasonably describe the phenomenon of isotropic compression curve of OC clay when approaching the normal consolidation line (NCL) under reloading, the unified hardening parameter used in the UH model is revised. Thirdly, a new overconsolidation parameter, which is crucial to make the UH model working with the elastic hysteretic stress-strain relationship effectively, is proposed. Then, a new small strain constitutive model, called the small strain UH (SSUH) model is presented in this paper. The proposed model is found to be able to describe highly nonlinear stress-strain relationship and stiffness degradation at small strains as well as the shear dilatancy and strain hardening/softening behaviors of OC clays at large strains. Besides, it needs only two additional parameter to consider the small strain behaviors compared with the modified Cam-clay (MCC) model.