A flexible and robust yield function for geomaterials

This paper presents a new Modified Cam Clay (MCC) type yield function, that is designed for robust and efficient use with implicit stress integration algorithms. The proposed yield function attains non-elliptical (e.g. tear and bullet) shapes, as well as the typical elliptical shape of the MCC model. Like that of MCC, and unlike most other yield functions with non-elliptical shapes available in literature, it is non-singular and unique throughout stress space. The experimental yielding stresses of a wide range of geomaterials have been accurately simulated using the yield surface. The yield function can be used in constitutive models based on classical elasto-plasticity theory. •A new flexible yield function for geomaterials is proposed.•The yield surface is unique and non-singular in meridian stress space.•The yield surface is robust for implicit stress integration schemes.•The yield surface is derived thermodynamically but can be used in all models.•Proposed yield surface matches experimentally observed yield loci of geomaterials.