抄録
The mathematical structure of the overstress type elasto-viscoplastic constitutive model is discussed. Derived is the analytical solution of undrained strength for Adachi and Oka model, a typical overstress type model. It has been recognized that this type of model cannot describe acceleration creep. This disadvantage was overcome on the basis of the assumption that viscoplastic parameter for Adachi and Oka model depends on the effective stress state and check it with experimental findings. The modified overstress type of elasto-viscoplastic constitutive model is found to be able to the creep rupture including acceleration creep of normally consolidated clay.
