A hardening/softening viscoplastic model for large deformation of soil

A three-invariant continuum cap plasticity model with viscoplastic features is developed for modeling the large deformation of soil. Multiple failure mechanisms including combined shear and compaction yielding and loss of strength under tension can be captured by this model. The shear yield surface of the model is formulated to be nonlinear and pressure-dependent. The model also features a cap surface that governs inelastic compaction hardening. This cap is formulated as an explicit expression of porosity. The differences in triaxial compression and extension strength are also considered. A set of numerical examples are carried out, including triaxial compression and compression-shear tests, in order to examine the model under confined loading conditions, and observe the formation of shear bands.

Automated summary

A three-invariant continuum cap plasticity model with viscoplastic features is developed for modeling the large deformation of soil, capturing multiple failure mechanisms.