One-dimensional elastic visco-plastic modelling of time-dependent behavior of structured soft clays

To explore the effect of structural damage on the time-dependent behavior of structural soils, a one-dimensional elastic visco-plastic (1DEVP) constitutive model is developed with introducing a new concept of constant visco-plastic strain rate lines, based on Bjerrum's time lines. To describe the progressive destruction, a new structural parameter named "structural strain" is defined and a new mathematical formula is proposed based on characteristics of soil structure degradation under the one-dimensional loading condition. The method for calibrating the proposed model is discussed, and the proposed model is used to simulate conventional compression tests on Wenzhou natural clays, step loading fast-consolidation tests on natural Ariake clays, constant rates of strain tests (CRS) oedometer tests and long-term creep oedometer tests on structured Berthierville clays. The comparisons between simulations and experimental results show that the newly proposed 1DEVP model can reasonably describe destructuration effects on the time-dependent behavior of structured soft clays.