关键词: 砂土, 剪胀, 软化, 显式积分

Abstract: Dense sand normally exhibits shear dilatancy softening under normal pressure and shear shrinkage hardening under high pressure. Therefore, unified model of sand and its numerical implementation is an important scientific problem for describing the loading response of dilatancy softening material, and it will also promote the progressive failure theory. In this study, the unified model of sand which reflects the mechanical properties of dense sand under normal and high pressure is firstly described, and then the key problem of numerical calculation for the model is analyzed. By using the explicit method, the secondary development of stress integration program is carried out. In the process of stress integration, loading-unloading criterion within strain space and smoothed failure surface are used for satisfying the judgment of loading condition and determination of plastic strain direction. An example is given to prove that the explicit method can overcome the difficulties in calculation for dilatancy and softening. This method shows a good way to analyze the mechanical behavior for materials with dilatancy softening and shrinkage hardening characteristics.

Key words: sand, shear dilatancy, softening, explicit integration