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The Ice Environment
Published in Rita A. Horner, Sea Ice Biota, 1985
Convergence and shearing motions cause the ice to fracture and pile up into a variety of deformation features, the most notable being pressure ridges. Pressure ridges form linear features up to several kilometers in length which consist of a keel beneath the ice and a sail on the surface of the ice. Keels are typically about five times thicker than sails. Most ridges in the Central Arctic appear to be built out of ice that was originally less than 1 m in thickness.11 This may not be true in all areas, however, as detailed morphological studies north of Prudhoe Bay, Alaska, indicated that nearly 50% of the ridges there were composed of blocks between 1.0 and 1.6 m in thickness.12 Ridge frequency in the Arctic Basin varies with season and location, but is generally in the range of 2 to 6/km. Keel depths are usually less than 20 m. It has been estimated13 that as much as 40% of the total mass in the Arctic ice pack may be contained in deformation structures. In contrast to the Arctic situation, ridges are generally believed to be uncommon in most parts of the Antarctic due to the divergent nature of the velocity field there. A notable exception is the Weddell Sea where ridged ice may account for more than 15% of the area.4
Validation of microparameters in discrete element modeling of sea ice failure process
Published in Particulate Science and Technology, 2019
Xue Long, Shunying Ji, Yuefang Wang
Sea ice composed of ice crystals, brine, and gas is a complex material in cold region engineering, whose formation depends upon temperature and various types of solid salts (Timco and Weeks 2010). Sea ice often fails in a compressive mode during the formation of large compressive pressure ridges or during crushing against vertical offshore structures, while it undergoes flexural failure mode when interacting with inclined structures (Moslet 2007; Shazly, Prakash, and Lerch 2009; Croasdale 2012). Thus, the uniaxial compressive strength () and flexural strength () of sea ice are two fundamental material strength properties on the macrolevel which have a direct effect on the ice load of offshore structures. Obviously, the strengths of sea ice are important criterion to measure the failure modes of sea ice, which directly affects the ice loads and failure modes during the interaction between the ice and structures. Researchers show a significant interest in experimental investigations for macroproperties of sea ice, i.e., elastic modulus and strengths that provide the basis for the development of numerical simulations (Ji et al. 2011; Lu, Lubbad, and Løset 2016).