A new elliptic-parabolic yield surface model revised by an adaptive criterion for granular soils

An adaptive criterion for shear yielding as well as shear failure of soils is proposed in this paper to address the fact that most criteria, including the Mohr-Coulomb criterion, the Lade criterion and the Matsuoka-Nakai criterion, cannot agree well with the experimental results when the value of the intermediate principal stress parameter is too big. The new criterion can adjust an adaptive parameter based on the experimental results in order to make the theoretical calculations fit the test results more accurately. The original elliptic-parabolic yield surface model can capture both soil contraction and dilation behaviors. However, it normally over-predicts the soil strength due to its application of the Extended Mises criterion. A new elliptic-parabolic yield surface mode is presented in this paper, which introduces the adaptive criterion in three-dimensional principal stress space. The new model can well model the stress-strain behavior of soils under general stress conditions. Compared to the original model which can only simulate soil behavior under triaxial compression conditions, the new model can simulate soil behaviors under both triaxial compression conditions and general stress conditions.