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  • 1
    Call number: ZSP-201-85/16
    In: CRREL Report, 85-16
    Description / Table of Contents: This report presents the results of the second phase of a test program designed to obtain a comprehensive understanding of the mechanical properties of multi-year sea ice from the Alaskan Beaufort Sea. In Phase 2, 62 constant-strain-rate uniaxial compression tests were performed on horizontal and vertical ice samples from multi-year pressure ridges to examine the effect of sample orientation on ice strength. Also conducted were 36 constant-strain-rate tension tests, 55 conventional triaxial tests and 35 constant-load compression tests on multi-year pressure ridge samples to provide data for developing ice yield criteria and constitutive laws. Data are presented on the strength, failure strain and modulus of multi-year sea ice under different loading conditions. The effects of ice temperature, porosity, structure, strain rate, confining pressure and sample orientation on the mechanical properties of multi-year sea ice are examined.
    Type of Medium: Series available for loan
    Pages: vi, 89 Seiten , Illustrationen
    Series Statement: CRREL Report 85-16
    Language: English
    Note: CONTENTS Abstract Preface Introduction Field sampling program Site selection and description Coring procedures Core logging procedures Shipping and storage of ice samples Ice description Salinity and density Structure Constant-strain-rate compression tests Test variables Uniaxial compressive strength Strength and structure Strength and porosity Residual compressive strength Failure strain Initial tangent modulus Constant-strain-rate uniaxial tension tests Test variables Uniaxial tensile strength Failure strains Initial tangent modulus Constant-strain-rate triaxial tests Equipment Test variables Synthane end caps Triaxial strength Failure strains Initial tangent modulus Effect of sinthane end caps on results Constant-load compression tests Test variables Test results Conclusions Literature cited Appendix A: Ice structure profile of ridge C core Appendix H: Test data Appendix C: Static determination of Young's modulus in sea ice
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  • 2
    Call number: ZSP-201-84/9
    In: CRREL Report, 84-9
    Description / Table of Contents: This report presents the results of the first phase of a test program designed to obtain a comprehensive understanding of the mechanical properties of multi-year sea ice from the Alaskan Beaufort Sea. In Phase I, 222 constant-strain-rate uni-axial compression tests were performed on ice samples from ten multi-year pressure ridges to examine the magnitude and variation of ice strength within and between pressure ridges. A limited number of constant-strain-rate compression and tension tests, constant-load compression tests, and conventional triaxial tests were also performed on ice samples from a multi-year floe to provide preliminary data for developing ice yield criteria and constitutive laws for multi-year sea ice. Data are presented on the strength, failure strain, and modulus of multi-year sea ice under different loading conditions. The statistical variation of ice strength within and between pressure ridges is examined, as well as the effects of ice temperature, porosity, structure, strain rate and confining pressure on the mechanical properties of multi-year sea ice.
    Type of Medium: Series available for loan
    Pages: v, 107 Seiten , Illustrationen
    Series Statement: CRREL Report 84-9
    Language: English
    Note: CONTENTS Abstract Preface Introduction Field Sampling Site selection and description Ice sampling procedures Shipping and storage of ice samples Testing Techniques Multi-year Pressure Ridge Tests Ice description Sampling scheme and test variables Uniaxial compressive strength Residual compressive strength Failure strains Initial tangent modulus Statistical Variations in Ice Strength Differences in strength above and below level ice Sources of the variation in strength Shape of the strength histograms Multi-year Floe Ice Tests Ice description Uniaxial compressive strength Constant-load compression tests Constant-strain-rate tension tests Triaxial tests Conclusions Literature Cited Appendix A: Structural profile of a multi-year pressure ridge core Appendix B: Ridge uniaxial compression test data Appendix C: Structural profile of the continuous multi-year floe core Appendix D: Multi-year floe test data
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  • 3
    Series available for loan
    Series available for loan
    Hanover, NH : Corps of Engineers, U.S. Army Cold Regions Research & Engineering Laboratory
    Associated volumes
    Call number: ZSP-202-269
    In: Research report
    Description / Table of Contents: CONTENTS: Preface. - List of symbols. - Introduction. - Structure of ice and ice sheets. - Ice as a mineral. - Lake and sea ice. - Chemistry and phase relations. - Dislocations,cracks,and stress concentrators. - Direct observation of dislocations. - Crackformation. - Stress concentration. - Theoretical considerations. - Experimental results. - Compressive strength. - Indentation failure. - Tensile strength. - Flexural strength. - Shear strength. - Impact strength. - Scale effects. - Strength deterioration in the spring. - Recommended research. - Summary. - Selected bibliography. - Abstract.
    Description / Table of Contents: The increased activity in cold regions has made a thorough understanding of fracture in lake and sea ice quite desirable, inasmuch as this information has application to a number of problems of geophysical as well as engineering importance. This survey starts with a discussion of the structure of ice I and the macro- and microstructure of sea and lake ice as well as their chemistry and phase relations. Recent work on the direct observation of dislocations as well as the formation of cracks in ice is summarized. Formal ice-brine-air models for analyzing variations in ice strength are also reviewed. The results of the different types of tests are discussed and cornpared (compressive, indentation, direct and ring-tension, small beam flexure and in situ cantilevers and simple beams, shear, and impact). Scale effects are considered as well as the rapid strength deterioration experienced by ice sheets in the spring. Finally, a number of recommendations are made concerning future research in this field.
    Type of Medium: Series available for loan
    Pages: viii, 79 S. : Ill.
    Series Statement: Research report / Cold Regions Research and Engineering Laboratory, CRREL, US Army Material Command 269
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  • 4
    Series available for loan
    Series available for loan
    Hanover, New Hampshire : U.S. Army Cold Regions Research and Engineering Laboratory
    Associated volumes
    Call number: ZSP-201-82/30
    In: CRREL Report, 82-30
    Description / Table of Contents: Equations are developed that can be used to determine the amount of gas present in sea ice from measurements of the bulk ice density, salinity and temperature in the temperature range o f-2 to -30°C. Conversely these relationships can be used to give the density of sea ice as a function of its temperature and salinity, considering both the presence of gas and of solid salts in the ice. Equations are also given that allow the calculation of the gas and brine volumes in the ice at temperatures other than that at which the bulk density was determined.
    Type of Medium: Series available for loan
    Pages: 13 Seiten , Illustrationen
    Series Statement: CRREL Report 82-30
    Language: English
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  • 5
    Call number: ZSP-202-315
    In: Research report
    Description / Table of Contents: CONTENTS: Preface. - Introduction. - Part 1:Mesoscale strain measurements on the Beaufort Sea pack ice. - Abstract. - Introduction. - Previous work. - Site location. - Results. - Correlation of synoptic aerial photography with measured strains. - Correlation of estimated wind stress and strain. - Conclusions. - Literature cited. - Part II: Structure of a multiyear pressure ridge. - Abstract. - Introduction. - Profiles. - Internal properties. - Largest ridge sail. - Conclusions. - Literature cited. - Part III: Top and bottom roughness of a multiyear ice floe. - Abstract. - Introduction. - Results. - Literature cited. - Part IV:Airphoto analysis of ice deformation in the Beaufort Sea Abstract. - Introduction. - Study area. - Method of analysis. - Ice deformations. - Net deformational changes. - Pressure ridge distribution. - Summary and conclusions. - Literature cited. - Part V: Data on morphological and physical characteristics of sea ice in the Beaufort Sea.
    Description / Table of Contents: The report is in five parts. Part I, Mesoscale Strain Measurements on the Beaufort Sea Pack Ice: Fracture (lead and crack) orientations in first-year ice indicate correlation with the orientation of the strain rate ellipse. A qualitative relation is suggested between the fracture density and the long-term divergence rate. Correlation was also observed between the divergence of the wind field, as computed from the surface pressure field, and the ice divergence. Part II, Structure of a Multiyear Pressure Ridge: Three transverse profiles were measured across a ľarge pressure ridge in the Beaufort Sea. The ridge sail extended 4 m above sea level and the keel 13 m below. The cross sections of the keel were roughly semicircular, suggesting that form drag coefficients for flow transverse to the long axes of multiyear ridges may be as high as 0.8. Part III, Top and Bottom Roughness of a Multiyear Ice Floe: A spectral study of the snow and ice topography of a multiyear floe showed that the snow cover attenuates the roughness amplitude of the ice surface but does not cover it completely. The snow surface variance is lower than the ice surface variance by a factor of 1/3 to 1/4. The correlation between snow and ice surface roughness is significant for long wavelengths (〉 8 m) but not for short wavelengths (〈 4 m). The ice sheet as a whole is in free-floating, isostatic equilibrium, but pronounced local deviations from isostatic equilibrium are common. Part IV, Air Photo Analysis of Sea Ice Deformation in the Beaufort Sea: The time, direction and magnitude of deformational motion were determined by combining observations of the changes in features related to ice deformation (leads, fractures, pressure ridges) with mesoscale measurements of strains and strain rates on the ice. Part V, Data on Morphological and Physical Characteristics of Sea Ice in the Beaufort Sea: Measurements of the size of ice blocks in newly formed pressure ridges and measurements of salinity and temperature are presented.
    Type of Medium: Series available for loan
    Pages: iii, 66 S. : Ill., graph. Darst., Kt.
    Series Statement: Research report / Cold Regions Research and Engineering Laboratory, CRREL, US Army Material Command 315
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  • 6
    Series available for loan
    Series available for loan
    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
    Associated volumes
    Call number: ZSP-202-310
    In: Research report
    Description / Table of Contents: CONTENTS: Introduction. - Field sites and procedures. - Results. - Discussion. - Conclusions. - Literature cited. - Appendix A: Tabulation of AIDJEX core data. - Appendix B: Tabulation of average salinity/ice thickness data. - Abstract.
    Description / Table of Contents: The salinity distribution in multiyear sea ice is dependent on the ice topography and cannot be adequately represented by a single average profile. The cores collected from areas beneath surface hummocks generally showed a systematic increase in salinity with depth from 0 0/00 at tne surface to about 4 0/00 at the base. The cores collected from areas beneath surface depressions were much more saline and displayed large salinity fluctuations. Salinity observations from sea ice of varying thicknesses and ages collected at various arctic and subarctic locations revealed a strong correlation between the average salinity of the ice, S, and the ice thickness, h. For salinity samples collected from cold sea ice at the end of the growth season, this relationship can be represented by two linear equations: S = 14.24 - 19.39h (h? 0.4 m) ; S = 7.88 - 1.59h (h 〉 0.4 m) . It is suggested that the pronounced break in slope at 0.4 m is due to a change in the dominant brine drainage mechanism from brine expulsion to gravity drainage. A linear regression for the data collected during the melt season gives S = 1.58 + 0.18h. An annual cyclic variation of the mean salinity probably exists for multiyear sea ice. The mean salinity should reach a maximum at the end of the growth season and a minimum at the end of the melt season.
    Type of Medium: Series available for loan
    Pages: iii, 23 S. : Ill., graph. Darst.
    Series Statement: Research report / Cold Regions Research and Engineering Laboratory, CRREL, US Army Material Command 310
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  • 7
    Series available for loan
    Series available for loan
    Hanover, NH : U. S. Army Cold Regions Research and Engineering Laboratory
    Associated volumes
    Call number: ZSP-201-88/13
    In: CRREL Report, 88-13
    Description / Table of Contents: 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.
    Type of Medium: Series available for loan
    Pages: v, 63 Seiten , Illustrationen
    Series Statement: CRREL Report 88-13
    Language: English
    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
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