Investigation of foundations behavior by implementation of a developed constitutive soil model in the ZEL method

Foundations behavior is affected by soil behavior which can vary from dilative to contractive depending on the stress level, particularly in dense frictional soils. The Zero Extension Lines (ZEL) method has been generally developed to predict the foundations behavior. Knowledge of soil behavior enables the ZEL method to predict the general and local shear failure modes. In this paper, a relatively simple work hardening/softening soil constitutive model is developed to represent dense frictional soils behavior under different stress levels. This model is based on the accumulation of the plastic work during a simple direct shear test and its relationship to stress ratio to establish the hardening law. Verifications have been made for the developed soil model. The model is then implemented into the ZEL method to theoretically investigate the bearing capacity and load-displacement behavior of foundations over dense frictional soils. Utilization of this model enables the ZEL method to capture different modes of failure depending on the foundation size. A numerical study on foundations behavior was performed showing the ability of the presented approach in capturing both failure modes.