Three-dimensional modeling of various soil features based on the tij concept

In this chapter, the advanced one-dimensional (1D) models, in which various soil features such as influence of density, bonding effect, time-dependent behavior, and others are uniquely considered. The descriptions in Chapter 3 are extended to three-dimensional (3D) models using the t_ij concept explained in the previous chapter (Nakai et al. 2011b). Also, a method to take into consideration the influence of stress path dependency on the direction of plastic flow, which is one of the features in multidimensional conditions, is presented and the explicit expression of the constitutive models based on the t_ij concept is shown, in order to apply these models to 2D and 3D geotechnical boundary value problems. The validities of the 3D models are confirmed by various kinds of element tests (triaxial tests, true triaxial tests, plane strain tests, and hollow cylinder tests) on clay and sand. Throughout these verifications, unified material parameters are used for clay and sand.