Saturated Sand Elastoplastic Constitutive Model

Stress-dilatancy and stress hardening are the basic characteristics for sands, a complete constitutive model should reflect the two basic features. People have made a lot of study on it now of the stress-hardening, people's understanding and use of it are almost mature, but Stress-dilatancy is quite complicated, factors are relatively large and the dilatancy research are still not perfect, so there are a lot of work to do right on the dilatancy much of a description.This article summarized the constitutive model of research and development it in this paper at first, made a simple research and summary of the sand's Stress-dilatancy the proposal on the Cambridge model was reviewed, proposed a state based on the phase transition dilatancy index, and dilatancy index is introduced into the Cambridge model, the establishment of a Cambridge-based model can accurately reflect changes in this sand dilatancy constitutive model, and by a large number of triaxial tests, the model simulation and verification. The main findings of this paper are:1. Loose sand in the shear reduction will occur shear conditions, while for the dense sand and other dilatancy material that dilation will occur after the shear force reduction; for the dilatancy of sand, the smaller the initial void ratio, the higher the corresponding peak stress and stress ratio, the lower phase transition; in this paper, the dilatancy index to the material phase-change state as the reference state, to better reflect the initial void ratio on the deformation process in which sand state are therefore suitable for describing dilatancy of sand dilatancy characteristics;2. Cambridge model is based on the theory of traditional plastic, with simple and practical features, but the Cambridge model can not properly describe the material by the shear dilatancy dilatancy reduced to the critical point of the deformation characteristics. This phase transition line by the dilatancy index for the reference to the Cambridge model introduced plastic potential function, the establishment of a new elastoplastic constitutive model, a better response to contraction and dense sand shear dilatancy characteristics. When it is Loose sand, the model can very naturally back into the degradation of the Cambridge model...