A Plasticity Model of Binary Mixtures for Liquefaction Simulation Considering the Equivalent Granular Void Ratio

Abstract

Most natural soil deposits are non-homogeneous granular materials consisting of coarse-grained particles with finer non-plastic particles filling the voids. Experimental results on binary mixtures are needed to assess the performance of constitutive models considering non-homogeneous granular materials. This study aims to calibrate and inspect an advanced constitutive model based on the generalized plasticity framework from monotonic and cyclic triaxial tests on binary mixtures. A state parameter-based model uses the global void ratio (e) and state parameter (ψ) as a unifying framework. The parameters e and ψ were substituted by e^* and ψ^* to check the performance of the framework in constitutive modeling, and both simulations were compared. Samples of binary mixtures (the coarse-grained particles: Ottawa sand; the fine-grained particles: Vietnam silica fine sand) were used to simplify the complex non-homogeneous granular materials where their particle shapes and size ratio have been considered to check the applicability of the proposed constitutive model. The triaxial monotonic tests were first used to check the model and calibrate the model parameters. The calibrated parameters from monotonic tests were applied to predict the amplitude of shear strain and the number of cycles until liquefaction in the undrained cyclic triaxial tests. This model cannot reproduce very well in the simulations of undrained cyclic triaxial test results, but the results show that the inclusion of e^* and ψ^* could be considered in the simulations under monotonic loading when accounting for the effects of fines content. Therefore, to accurately predict liquefaction behaviors, more laboratory data must be used to improve this unified framework.