Author(s): Yoshikatsu Yasunaga; Shinji Kioka; Yuko Matsuo; Atsumi Furuya; Hiroshi Saeki
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Abstract: Unconsolidated layer of ice ridge is composed mostly of loosely accumulated broken ice pieces. Although its strength is low, it imposes large load on offshore structure when it forms in sufficient size. Also it effects on submarine structure due to ice scour event. It is important to know strength of the unconsolidated layer. In this study, a simplified unconsolidated layer model was produced as a Mohr-Coulomb material, and a series of preliminary experiments (direct shear tests) was performed. As main results, shear strength satisfied the Coulomb failure criterion. The apparent cohesion and angle of internal friction increased with the ice block/piece size that constitutes the unconsolidated layer. However, the increase of angle of internal friction deceased as the ice block size increased, and the angle of internal friction seems to approach a constant value. And, although the shear strength had a peak value at a certain shear deformation rate, it approached constant value as the shear deformation rate increase after the peak.
Year: 2002