ABSTRACT
This paper presents a time dependent constitutive model, namely NSFS-MCC, developed based on nonstationary flow surface theory and in the framework of critical state soil mechanics. The model is capable of capturing the effect of time and loading rate on the long term behaviour of soft soils. Model description is presented before some qualitative and quantitative simulations to verify the model’s capacity. Determination of model parameter values via standard laboratory test data is also introduced. The new model has six parameters in total, among which two parameters refer to the creep effects and the remaining four are associated with the Modified Cam-Clay (MCC) model. Three different loading scenarios, over an arbitrary soil type, are simulated to verify the model’s performance in capturing different aspects of time and rate effects. Furthermore, experimental data from tests on two different clays, namely Haney clay and Osaka clay, are used to validate the prediction capability of the NSFS-MCC model at element test level. The numerical modelling results show that the new model can capture well the time and rate dependent nature of clayey soils.
