Disturbed state concept-based constitutive model for lignosulfonate-treated silty sand

In this paper, a new behavioral (plasticity) model for lignosulfonate (LS)-treated silty sand based on the disturbed state concept is proposed. Here, the relative intact (RI) responses for both the LS-treated and untreated soils are simulated using the δ0 version of the hierarchical single-surface plasticity models. The nonassociativeness is incorporated through the disturbance function, which shows the amount of deviation of the actual response from the reference states. In the analysis, the fully adjusted (FA) response of the untreated soil was considered similar to the shear behavior at 20% of the shear strain. Also, for the LS-treated behavior, the FA response was taken as the response of the LS bonds. In this study, the bond response was modeled separately using a linear elastic RI response and zero strength condition as the relative states. A series of laboratory direct shear tests were carried out at low effective normal stresses to determine the model parameters. The proposed model has been validated using an independent set of shear test results. The model predictions are in good agreement with the laboratory test data.