A note on the Mohr–Coulomb and Drucker–Prager strength criteria

This paper presents different expressions of the Mohr–Coulomb (M–C) criterion as well as the interrelationships between them, which lays a foundation for the definition of the equivalent M–C friction angle φmc. The characteristics of four types of Drucker–Prager cones matched with the M–C surface are compared as the friction angle φ varies from 0° to 90°. The minimum and maximum value of φ for them is given and the influence of the intermediate principal stress σ2 to the major principal stress σ1 is demonstrated using their φmc.