Abstract
For the analytical prediction of plastic deformation behavior in soil, two yield criteria and hardening characteristics are required. The criteria are the criterion in deviatoric surface and that in main yield surface. The former provides the condition between deviatoric stresses and the latter does the condition between hydrostatic pressure and equivalent deviatoric stress under plastic deformation. Because the third invariant of deviatoric stress has not a little influence on the shape of yield curve, special consideration is taken into the basic equivalent deviatoric stress used in the main yield surface. In addition to volumetric strain, equivalent deviatoric strain influences hardening characteristics. Moreover, it became evident for the universal representation of hardening characteristics that the factor relating to the gradient of a loading path is needed besides these strains. The paper shows the concrete procedures for determining the characteristic values of hardening, and discusses these methods.
