Creep tests and creep model for reconstituted over-consolidated saturated clay

The triaxial shear creep tests are carried out on the reconstituted over-consolidated clay samples (OCR=1.00, 1.25, 1.67, 2.00, 3.00) from Hangzhou, China. The time-dependent deformation characteristics and creep model for the over-consolidated saturated clay are studied, and the values of model parameters are analyzed. The results show that the stress-strain curve of the reconstituted over-consolidated saturated clay has strain-hardening characteristics. The time-deformation curves of the over-consolidated clays under constant deviator stress are of hyperbolic characteristics. The larger the over-consolidation ratio, the smaller the excess pore pressure generated at the initial stage of the deviator stress application, the earlier the creep stage starts, and the smaller the creep evolution of the sample within a certain time. Based on the "pore pressure dissipation method", the t_EOP of the over-consolidated clay is determined. The hyperbolic creep model can highly fit the shear creep curves of the over-consolidated saturated clay. The curve fitting analysis shows that under the same deviator stress, the final creep values of the samples with different over-consolidation ratios are roughly equal. However, the larger the over-consolidation ratio, the slower the creep development of clay. The hyperbolic creep model parameter A_s almost remains constant when the over-consolidation ratio changes, while the parameter B_s approximately linearly increases with the increase of the over-consolidation ratio.