RUBBLE ICE TRANSPORT ON ARCTIC OFFSHORE STRUCTURES (RITAS), PART Ⅱ: 2D SCALE-MODEL STUDY OF THE LEVEL ICE ACTION

摘要

A model scale experiment on the interaction between level ice and an arctic offshore structure with a downward bending hull was conducted in April 2012 in the large ice tank of HSVA. The experiments investigate the different mechanical processes contributing to the ice action. The present paper is completed by a companion paper "Rubble Ice Transport on Arctic Offshore Structures (RITAS), part I: Model scale investigation of level ice action mechanisms". Detailed investigations on special aspects of the level ice action mechanisms are presented in "Rubble Ice Transport on Arctic Offshore Structures (RITAS), part III: Analysis of scale model rubble ice stability" and "Rubble Ice Transport on Arctic Offshore Structures (RITAS), part IV Tactile sensor measurement of the level ice load on inclined plate". The structure, a so called buoyancy box, is inclined at the waterline and promotes a downward bending failure of the level ice. Two-dimensionality is introduced by limiting the panel width to 1 meter with two transparent Lexan plates allowing monitoring of the ice breaking and accumulation process. Several parameters are varied: ice thickness, ice density, ice velocity. A tactile sensor is installed on the ice breaking area of the structure to monitor the local waterline ice loads. During each interaction tests, the volume and buoyancy of the rubble accumulated on the structure are measured for derivation of the rubble porosity. The waterline ice load is oscillating. The experimental results show that the magnitude of the load peaks increases. The rubble is subjected to a rotating motion and to a series of collapse events. Increased buoyancy forces reduce the rubble porosity.