Constitutive modeling of unsaturated soil behavior under axisymmetric stress states using a stress/suction-controlled cubical test cell

Two elasto-plastic critical state-based formulations for modeling the constitutive behavior of an unsaturated soil are presented and briefly discussed. Computational constitutive drivers were implemented to allow for the numerical simulation of suction-controlled conventional triaxial tests. Simulations were obtained from explicit and implicit integration techniques. The algorithms support numerical analyses in a deviatoric stress plane by using a mixed control constitutive driver in conjunction with a generalized cam-clay model, within a constant-suction scheme. The results from a series of suction-controlled conventional triaxial tests conducted on several identically prepared, 10-cm side, cubical specimens of compacted silty sand, using a recently developed stress/suction-controlled cubical testing device, were used for validation of the models and the enhanced features proposed in the present work. Matric suction states in the specimens were induced and maintained constant during testing by using the axis-translation technique.