Brash Ice Behavior.

• Main Author: Greisman,Paul
• Other Authors: COAST GUARD RESEARCH AND DEVELOPMENT CENTER GROTON CT
• Format: Text
• Language: English
• Published: 1981
• Subjects: Snow; Ice and Permafrost; Civil Engineering; Marine Engineering; *Ice; Fragments; Channels(Waterways); Mechanical properties; Ship hulls; Interactions; Resistance; Laboratory tests; Field tests; *Brash ice; Mohr-Coulomb theory; Ice; permafrost
• Online Access: http://www.dtic.mil/docs/citations/ADA104152; http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA104152

The behavior of brash ice, its formation and recommended vessel operating procedures are presented. Brash ice behaves as a Mohr-Coulomb solid below a critical strain rate or ship speed. Above this speed, fluidization of the medium occurs and the resistance appears to be that of a viscous, laminar fluid. The optimum operating speed for a vessel in brash is at the viscous threshold, found here to be 0.12 sg.rt of gL) where g (32.2 fS-2) is the acceleration of gravity and L is the length of the vessel. Repeated passages through brash-filled channels to keep them unconsolidated are generally unadvisable due to the attendant enhancement of the accretion rates. The laboratory and field experiments employed in this study are presented. Laboratory tests in brash ice appear to yield very useful results that are good predictors of full-scale resistance. (Author)