Systematic calibration of constitutive models for numerical simulation of seismic slope stability

In this study, the effect of the calibration process of constitutive models in the numerical modeling of the dynamic slope instability problem was investigated. Two classes of common constitutive models, advanced (SANISAND) and simple (HSS) were used to simulate the dynamic response of the slope in FLAC^3D software. Both of the constitutive models were first calibrated in the element scale using the results of cyclic triaxial tests and resonant columns on Babolsar sand, then the capability of these models to predict the dynamic response of a physical model slope made of Babolsar sand and the prototype scale slope was evaluated versus the shaking table test results. Simulation results showed that the SANISAND model, despite having more advanced parameters for simulation of different soil properties such as stiffness, plastic hardening and dilatancy, predicts the slope displacement response with a very low accuracy, unlike the hardening soil model. The results of sensitivity analysis on SANISAND parameters showed that the influence of important factors such as the problem scale and the seismic input characteristics (i.e., Arias intensity and amplitude of harmonic input) should be considered in the process of calibrating the plastic hardening (h₀) and dilatancy (A₀) parameters. Finally, the variation charts of h₀ parameter versus variations of slope height to length ratio (H/D), amplitude and Arias intensity of harmonic input were presented. Considering to the increasing use of the family of constitutive models within the framework of critical state soil mechanics and bounding surface plasticity, these charts can be useful in the estimation of the appropriate value of plastic hardening parameter (h₀).