Calibration and validation of a new elastoviscoplastic soil model

Abstract

© 2020 John Wiley & Sons Ltd. This paper presents the calibration and validation for a new 3D elastoviscoplastic soil model, MIT-SR, for Resedimented Boston Blue Clay (RBBC). The calibration procedure requires selection of material constants from standard types of laboratory consolidation and undrained shear tests, and a procedure for initialization of state variables. The formulation includes two key input parameters that describe sensitivity of rate dependence, β, and creep behavior, ρα, for which the calibration requires data including CRS consolidation tests at a range of strain rates and drained creep tests. The calibrated MIT-SR model is benchmarked through a series of simulations of K0-consolidated triaxial shear tests and direct simple shear tests on RBBC performed at different rates of shear strain. The calibrated model provides very good predictions of the effects of shear strain rate on key engineering properties such as undrained shear strength, strain to peak shear resistance and critical state conditions as functions of the consolidation stress history. The predictions of multistage, undrained relaxation tests are also in good agreement with unique measured behavior reported for RBBC. The comparisons provide clear evidence of the advances in predictive capabilities achieved using the proposed MIT-SR formulation compared to preexisting isotache-type models.