Mohr–Coulomb yield curves for viscous-plastic sea ice models: flow rules and failure angles

Abstract. Viscous-plastic sea ice models typically overestimate the intersection angle between conjugate pairs of Linear Kinematic Features (LKFs) in uni-axial compression tests. These models employ an elliptical yield curve with a normal flow rule. Mohr-Coulomb yield curve formulations can use different plastic potentials (elliptical, teardrop, parabolic lens) implying different flow rule orientations along the limbs of the Mohr-Coulomb yield envelope. The flow rule affects not only the LKFs intersection angle, but also the numerical convergence of the model and the approach to transitions between viscous and plastic states. Some of the proposed Mohr-Coulomb yield curves results in failure angles in the observations 15–30 degree range, which is generally smaller than the ones obtained with the elliptical yield curve with a normal flow rule. The simulated failure angles are best described by Arthur's theory, where both shape of the yield curve and plastic potential influence the orientation of the failure lines. These new Mohr-Coulomb formulations, in particular the Mohr-Coulomb yield curve with elliptical plastic potential with wide ellipse (e < 2) or the Mohr-Coulomb yield curve with the teardrop plastic potential, provide interesting alternatives to the elliptical yield curve for the modeling of LKFs in high-resolution sea ice models, at the cost of a less efficient numerical convergence.