Predictive ability of strain rate effect on soft clay behavior

Using a spacing ratio of critical state, an elasto-plastic constitutive model is proposed in order to flexibly represent undrained behavior of various normally consolidated clays. The spacing ratio of critical state can be simply evaluated from the normalized undrained strength, and the proposed model has precisely predicted the stress paths and stress-strain relationships, compared with the modified Cam-clay model, with respect to undrained triaxial test results. Furthermore, the proposed model has an ability to predict the effects of strain rate on the constitutive relationship for the interested range of strain rates. It might be said that strain rate effect of normally consolidated clay is related to the secondary consolidation.