LOCALIZED PRESSURES DURING ICE-STRUCTURE INTERACTION - RELEVANCE TO DESIGN CRITERIA

Citation
Me. Johnston et al., LOCALIZED PRESSURES DURING ICE-STRUCTURE INTERACTION - RELEVANCE TO DESIGN CRITERIA, Cold regions science and technology, 27(2), 1998, pp. 105-117
Citations number
19
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Geosciences, Interdisciplinary",Engineering,"Environmental Sciences
Journal title
ISSN journal
0165-232X
Volume
27
Issue
2
Year of publication
1998
Pages
105 - 117
Database
ISI
SICI code
0165-232X(1998)27:2<105:LPDII->2.0.ZU;2-T
Abstract
Crushing is a prevalent mode of ice failure during ice-structure inter action. This failure mode frequently occurs with vertical structures a nd over local areas on sloping structures. During ice crushing, the in teraction zone is characterized by three distinct regions of pressure; critical zones, regions of background pressure, and areas of recently spalled ice. Critical zones may be defined as local regions of ice wh ere intense pressures occur over short time periods. Critical zones in fluence significantly the crushing process. The parameters associated with critical zones are quantified by examining three types of field-s cale interactions; medium-scale indentation tests, ship ramming trials of the Louis S. St. Laurent and CanMar Kigoriak, and an ice-structure interaction with the offshore structure Molikpaq. Critical zones occu r regardless of the scale or type of interaction. Despite the highly r andom nature of critical zones, basic parameters such as zonal size, f orce, pressure, and spatial density are quantified. Critical zones are found to be approximately 0.10 m(2) in area and may exert forces rang ing from 0.1-4 MN. Spatial densities of the critical zones, defined as the number of zones per unit meter, range from about 0.6 to 0.8 zones /m(2) and appear to be influenced by confining pressure and scale effe cts. Critical zones provide an explanation for the exhibited reduction in average pressure with increasing contact area. Two kinds of pressu re-area relationships are presented; one in which the contact area inc reases over time, the other in which large, unconfined contact areas c ontain smaller, highly confined regions,The importance of aspect ratio in relation to the pressure-area trend is discussed. Reduction in con tact area due to spalling and the orientation of the critical zones wi thin an impacted area are examined with respect to the aspect ratio. ( C) 1998 Elsevier Science B.V. All rights reserved.