Study on the collision between a ship and ice ridge considering macro-porosity in ice

• The ice ridge porosity models were established by randomly deleting finite units. • Consolidated ice ridges exhibited dual-peak load characteristics during collision. • The peak ice loads increased non-linearly with keel depth during repeated ramming. The opening of Arctic shipping routes enables shorter voyages and enhances economic efficiency. An ice ridge, a typical extreme ice condition in polar regions, generates ice loads during interactions with structures; they are commonly designated as ultimate design loads in polar marine and offshore engineering. Field observations reveal that macro-porosity, a distinctive characteristic of ice ridges arising from their complex formation processes, significantly influences mechanical properties of the ice ridge and ice load behavior. To analyze the load and fracture characteristics of ice ridges, model tests of the icebreaker-ice ridge collision were conducted in an outdoor ice tank. Based on the experimental data, two numerical ice ridge models incorporating various macro-porosity modelling were developed and validated. The interaction processes between ice ridges and structures were simulated, with keel depths analyzed for their effects on failure mechanisms of the ice ridge and ice loads. The failure progression under multiple impacts and the number of collisions required to damage the ice ridge were further investigated. These findings aim to provide some practical references for icebreaker structural design and operational strategies.