A REDUCTION MEASURE AGAINST COLLISION FORCES CAUSED BY BRITTLE MATERIALS SUCH AS SEA ICE TO STRUCTURE BASED ON MEDIUM-SCALE EXPERIMENTS AND NUMERICAL CALCULATIONS

Abstract

 Medium-scale experiments and numerical calculations by DEM were performed to investigate the reduction effects of protuberances such as a semi-cylinder attached to the surface of a structure (flat plane) on the collision force of sea ice. An ice collides with the flat plane after collision to the semicylinder to cause split failure. Each collision force of the sea ice to the semi-cylinder and the flat plane following it was significantly decreased compared to a single flat plane. The collision force was found to be minimal when the ratio of ice width (B) and diameter of the semi-cylinder (Φ) (B/Φ) was 3 -4, and the force decreased up to 20% of that to the single flat plane. The numerical calculation results agreed well with the experimental results. As one of measures to reduce collision force caused by brittle materials such as sea ice, the validity of an attachment such as small sized protuberances that could lead to fracture to the surface of a structure were confirmed.