Numerical modeling of creep degradation of natural soft clays under one-dimensional condition

Creep degradation is a common phenomenon of natural soft clays. This paper focuses on developing a one-dimensional constitutive model considering the influence of bond degradation on the creep behavior for natural soft clays. First, conventional oedometer creep tests are studied and a creep based structure indicator ϖ denoting the difference between the creep coefficient of the reconstituted samples and that of intact samples is proposed. Then, the creep coefficient of intact clay is formulated by this indicator and the intrinsic creep coefficient corresponding to reconstituted clay. This formula is then incorporated into a one-dimensional creep model to describe the creep degradation behavior induced by bond degradation. The model parameters can be determined in a straightforward way from oedometer tests which leads to an easy application of the model for practice. Furthermore, coupled with the consolidation theory, the model is used to simulate oedometer tests at constant strain rate as well as long-term creep tests on sensitive Batiscan clay. The destructuration effects on the evolution of creep coefficient are analyzed. The comparisons between experimental and numerical results show that the proposed model can precisely describe the creep degradation behavior induced by destructuration of natural soft clay under one-dimensional loading.