DEM simulations of direct shear box experiments of ice rubble: Force chains and peak loads

This paper introduces 2D discrete element method (DEM) simulations of laboratory scale direct shear box experiments on ice rubble. The modeled experiments were performed in a cold laboratory at the Norwegian University of Science and Technology (NTNU). The simulations were first validated by comparison to experiments and then used to study the behavior of the rubble in the experiments in detail. After this the simulations were used to study the phenomena behind the shear force records in the experiments. The simulation results clearly demonstrate the need to account for the granular behavior of ice rubble when interpreting the experiment results: the peak loads measured in the experiments are due to force chains that form within the rubble as it goes through shear deformation during the experiment. The peak load values are on the other hand limited by the buckling of the force chains. The implications of these findings are first discussed from the aspect of interpretation of direct shear box experiment results for ice rubble, which is a material with a large block size, and then from the aspect of understanding ice loads in general. The results suggest that when estimating ice loads, the load limiting mechanism has to be carefully taken into account. (C) 2015 Elsevier B.V. All rights reserved.