GROUNDED ICE PILE-UP. 2D DEM SIMULATION

摘要

Studies of grounded ice rubbles formation aimed at the evaluation of their limit geometry and their potential effect on ice loads on shallow water platforms were performed. Based on observations and model studies the mechanisms for rubbles building up were developed. Numerical and analytical methods for modeling ice rubbles formation were suggested. Scenarios of coastal ice rubble formation include the following stages: fracture of the ice cover edge and formation of ice block chains (rubble supply lines) advancing a coastal slope, accumulation of ice blocks due to changes in the inclination of the sliding surface or due to supply line loss of stability caused by resistance to the ice block motion, and formation of new supply lines. Then the cycle is repeated. Limit rubble height when the amount of advancing ice is unlimited is determined by supply lines breaking up due to loss of stability of an ice block chain under a longitudinal compressive load. Various scenarios of the supply lines formation, the shape and size of occurring rubbles are discussed. Criteria for selected stages of particular scenarios were developed, including the ice edge breaking conditions, critical angle of supply line overturn, loss of stability critical load, as well as the modifications of limit states due to the geometry and strength of the obstacles. Analytical estimates were compared with the results of numerical DEM simulations. In particular, the problem of grounded rubble formation against a slope structure due to advancing ice accounting for various parameters of the system was considered. A modified version of known ice load equations for slope shallow water structures is proposed.