Creep behavior of Boom Clay

The Boom Clay is a kind of tertiary uniform and fine clay sediment. Because of its complicated mechanical characteristics, especially evident creep characteristic, a series of laboratory tests, including one-dimensional compression creep tests(CCT) and triaxial creep tests(TCT) have been conducted;and creep deformation characteristics of Boom Clay are researched under different pressures and different types of experiments. A separated yield surface creep constitutive model implicit time in formula with irreversible strain variable is established after theoretical analysis. It can avoid the difficulty of determining the creep times when resolving the actual calculation under complicated working condition by the traditional model with explicit time. Finally, the numerical implementation of the new creep constitutive model is implemented;and the creep test on Belgian Boom clay is simulated. The results show that the new constitutive model and the UMAT subroutine in ABAQUS have good calculation accuracy and good stability, which could effectively depict the nonlinear creep characteristic of Belgian Boom Clay.