Numerical Modeling of Ice–Seabed Interaction in Clay by Incorporation of the Strain Rate and Strain-Softening Effects

Abstract

Ice gouging is one of the main threats to the safety of the subsea pipelines buried in Arctic coastal regions. Determining the best pipeline burial depth relies on free-field ice gouging analysis and obtaining the resultant subgouge soil deformations. Therefore, improving the accuracy and efficiency of the free-field ice gouging analysis is a key demand in daily engineering practice. The pressure induced by the ice keel through the ice gouging process causes the seabed soil to undergo large localized plastic deformation, where the classical Lagrangian method confronts mesh instability challenges. Also, the conventional Mohr-Coulomb soil model is not able to account for the strain rate dependency and strain softening effects which are significant in ice gouging events. In this study, free-field ice gouging in clay was simulated using a Coupled Eulerian-Lagrangian approach. The strain rate dependency and strain-softening effects were incorporated by developing a user-defined subroutine and incremental updating of the undrained shear strength in ABAQUS. The comparison of the model predictions with published numerical and experimental studies showed a significant improvement in accuracy. A comprehensive parametric study was also conducted to investigate the effect of various model parameters on the seabed response to ice gouging.