UID:
kobvindex_GFZ20190724152222
Format:
v, 63 Seiten
,
Illustrationen
Series Statement:
CRREL Report 88-13
Content:
In many sea ice engineering problems the ice sheet has been assumed to be a homogeneous plate whose mechanical properties are estimated from the bulk salinity and average temperature of the ice sheet. Typically no regard has been given to the vertical variation of ice properties in the ice sheet or to the time of ice formation. This paper first reviews some of the mechanical properties of sea ice, including the ice tensile, flexural and shear strengths, as well as the ice modulus. Equations for these properties are given as functions of the ice brine volume, which can be determined from the ice salinity and temperature. Next a numerical, finite difference model is developed to predict the salinity and temperature profiles of a growing ice sheet. In this model ice temperatures are calculated by performing an energy balance of the heat fluxes at the ice surface. The conductive heat flux is used to calculate the rate of ice growth and ice thickness by applying the Stefan ice growth equation. Ice salinities are determined by considering the amount of initial salt entrapment at the ice/water interface and the subsequent brine drainage due to brine expulsion and gravity drainage. Ice salinity and temperature profiles are generated using climatological data for the Central Arctic basin. The predicted salinity and temperature profiles are combined with the mechanical property data to provide mechanical property profiles for first-year sea ice of different thicknesses, grown at different times of the winter. The predicted profiles give composite plate properties that are significantly different from bulk properties obtained by assuming homogeneous plates. In addition the failure strength profiles give maximum strength in the interior of the sheet as contrasted with the usual assumption of maximum strength at the cold, upper ice surface. Surprisingly the mechanical property profiles are only a function of the ice thickness, independent of the time of ice formation.
Note:
CONTENTS
Abstract
Preface
Introduction
Structure
Composition
Mechanical properties
Strength
Elastic constants
The temperature-salinity model
Temperature profiles
Salinity profiles
Composite plate properties
Results
Conclusions
Literature cited
Appendix A: Details of the equations for ice surface temperature and conductive heat flux
Appendix B: Calculated profile and bulk properties of an ice sheet of varying thickness
Appendix C: Calculated profile and bulk properties of 30- and 91-cm-thick ice sheets
In:
CRREL Report, 88-13
Language:
English
Keywords:
Forschungsbericht
URL:
https://apps.dtic.mil/docs/citations/ADA213087
URL:
https://hdl.handle.net/11681/9071
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