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  • 1
    Series available for loan
    Series available for loan
    Wilmette, Ill. : Snow Ice and Permafrost Research Establishment, Corps of Engineers, U.S. Army
    Associated volumes
    Call number: ZSP-202-46
    In: Research report / Cold Regions Research and Engineering Laboratory, 46
    Description / Table of Contents: Summary: The results of studies in the summer of 1957 on ice samples taken from the ice tunnel at TUTO, core samples obtained by drilling in the ice cap at Site 2, and snow samples, using the transverse vibration method and a new portable meter, are reported. Young's modulus was determined from the resonance frequency of flexural vibrations of samples cut in the form of rectangular bars; the loss factor was measured from damping; and the coefficient of viscosity calculated using the Maxwell model. The modulus of elasticity of samples of a density from 0.917 - 0.90 g/cm^3 (tunnel ice) decreased sharply with slight deviations of the density from that of pure ice. At densities from 0.90 - 0.50 g/cm^3 (deep-pit and drill-core samples) the relation between the modulus of elasticity and density was linear, while in the density range from 0.50-0.25 g/cm^3 (surface snow) the modulus of elasticity decreased exponentially. The viscosity-density relation of the samples was similar to that of elasticity vs density. Young's modulus increased slightly with decreasing temperature, while viscosity increased exponentially. The activation energy was calculated as 18.7 kcal/mol for old ice-cap ice, 13.9 kcal/mol for tunnel ice with elongated bubbles, and 13.5 kcal/mol for super-imposed ice.
    Type of Medium: Series available for loan
    Pages: v, 29, A4 Seiten , Illustrationen
    Series Statement: Research report / Cold Regions Research and Engineering Laboratory 46
    Language: English
    Note: CONTENTS Preface Summary Introduction Principle of measuring the visco-elastic nature of snow and ice by the vibration method Experimental method for determination of visco-elastic properties of snow and ice Visco-elastic properties of tunnel ice Elastic properties of snow samples from the deep pit Elastic properties of core samples obtained by drilling Elastic properties of snow near the ice-cap surface Vertical variation of Young's modulus near the surface Wind-packed snow Peter snow Relation between Young's modulus and density of snow Relation between Young's modulus and density over the range from surface snow to ice Supplementary experiments on the elastic nature of snow and ice at Site 2 Anisotropy of Peter snow Age hardening Temperature dependence of Young's modulus of core ice Viscosity measurement of snow and ice in Greenland Further experiments on the elastic nature of tunnel ice Temperature dependence of Young's modulus Frequency dependence of Young's modulus Further experiments on the viscous nature of tunnel ice Temperature dependence of loss factor Activation energy Frequency dependence of loss factor and viscosity Relation between viscosity and density Conclusions References Appendix: Experimental data
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  • 2
    Series available for loan
    Series available for loan
    Wilmette, Ill. : Snow Ice and Permafrost Research Establishment, Corps of Engineers, U.S. Army
    Associated volumes
    Call number: ZSP-202-47
    In: Research report / Cold Regions Research and Engineering Laboratory, 47
    Description / Table of Contents: Summary: Various mechanical properties such as strength, elastic modulus, and density of TUTO tunnel and ramp ice were determined. Results of unconfined compressive strength, ring tensile strength, and flexural strength tests are given. Photographs of included bubbles and grain size and shape are shown for each of six types of ice tested. Petrofabric diagrams for each type of ice are included. No significant differences in strength were found between horizontal and vertical cores in the ice tunnel, although differences between types of ice are noted. Crushing strength values found for tunnel ice generally fit the empirical equation relating crushing strength to density which was found for high-density snows (Butkovich, 1956a). However the values for ramp ice do not fit the equation when the average density values are used, probably due to the layering. The empirical equation relating ring tensile strength to density of high-density snows (ibid.) gives results approximately 20% greater than those obtained for tunnel ice. It appears that grain size influences the results. Ice with large grains consistently gives lower values. Flexural strength of the ramp ice is about half that of the tunnel ice. Comparing these results with the ring tensile values leads to the conclusion that the beams tend to fail in the lowest-density (mostly bubbly) bands. Temperature curves as a function of depth into the wall and along the tunnel length are presented. A 30-day study of deformation in a 100 x 30 ft room at 650 ft. into the tunnel indicated that the room is closing primarily by a block action, with rates of closure being less only very near the walls.
    Type of Medium: Series available for loan
    Pages: iv, 17 Seiten , Illustrationen
    Series Statement: Research report / Cold Regions Research and Engineering Laboratory 47
    Language: English
    Note: CONTENTS Preface Summary Introduction Strength Crushing strength Ring tensile strength Flexural strength Static modulus of elasticity Dynamic modulus of elasticity Density of tunnel and ramp ice Tunnel temperature measurements Crystal size, bubble size, and ice fabrics Deformation measurements Discussion of strength test results References
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  • 3
    Series available for loan
    Series available for loan
    Wilmette, Ill. : Snow Ice and Permafrost Research Establishment, Corps of Engineers, U.S. Army
    Associated volumes
    Call number: ZSP-202-51
    In: Research report / Cold Regions Research and Engineering Laboratory, 51
    Description / Table of Contents: Summary: The study was made in order to simulate the deformation of a tunnel in glacier ice and compare the results with the theoretical value derived from compression or tension tests. The plastic deformation of commercial polycrystalline ice and manufactured snow-ice was determined by measuring the discharge of oil from the cavity of closed hollow ice cylinders subjected to high external pressure in an oil-filled pressure chamber. The deformation vs time curves were similar to those obtained in compression or tension tests. The relationships between minimum strain rate and applied pressure, or between minimum strain rate and the circumferential stress at the surface of the inner cavity, were found to differ from the power law ϵ ̇= ασⁿ, the value of n being an increasing function of stress. Analysis of time deformation curves indicates that viscoelastic models proposed by former investigators do not apply to the mechanism of the plastic deformation of ice.
    Type of Medium: Series available for loan
    Pages: iv, 10 Seiten , Illustrationen
    Series Statement: Research report / Cold Regions Research and Engineering Laboratory 51
    Language: English
    Note: CONTENTS Preface Summary Introduction Apparatus Specimens Experimental procedures and results Analysis of the data Discussion References
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  • 4
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    Series available for loan
    Wilmette, Ill. : Snow Ice and Permafrost Research Establishment, Corps of Engineers, U.S. Army
    Associated volumes
    Call number: ZSP-202-52
    In: Research report / Cold Regions Research and Engineering Laboratory, 52
    Description / Table of Contents: Summary: The results of studies on the physical properties of fog whiteout, as it occurred at Site 2 on the Greenland Ice Cap in the summers of 1956 and 1957, are reported and compared with the results of other studies; the instruments, methods of measurement, and data-reduction techniques used are described; and attempts at dissipating whiteout by AgI (silver iodide) seeding are discussed briefly. Emphasis was given to measurements of fog-particle size distribution, liquid-water content, relative humidity, visibility, and atmospheric nuclei. The data are tabulated. The synoptic situations for 2 selected cases of fog whiteout at relative humidities of less than 100% (possibly because of the presence of salt solutions) are described; and the balance between the rate at which water is made available in the air as it is lifted over the Ice Cap and the rate of water flux to the snow surface is computed using various equations. Efforts at fog dispersal by AgI seeding from the ground were inconclusive.
    Type of Medium: Series available for loan
    Pages: iv, 18, A1 Seiten , Illustrationen
    Series Statement: Research report / Cold Regions Research and Engineering Laboratory 52
    Language: English
    Note: CONTENTS Preface Summary Introduction Definition of whiteout Scope of this study Instrumentation and observations Location of project: Fog particle measurements Atmospheric humidity measurements Visibility measurements Air temperature measurements Radiation measurements Atmospheric nuclei Observations of fog whiteout Conditions prior to onset of whiteout Conditions at time of arrival and during whiteout Micro-structure of fog whiteout Analysis of moisture balance during two selected cases Synoptic situation for case 1 Synoptic situation for case 2 Computations Attempts at fog whiteout dispersal References Appendix A - Freezing nuclei observations Appendix B - Absolute humidity gradient data
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  • 5
    Series available for loan
    Series available for loan
    Wilmette, Ill. : Snow Ice and Permafrost Research Establishment, Corps of Engineers, U.S. Army
    Associated volumes
    Call number: ZSP-202-53
    In: Research report / Cold Regions Research and Engineering Laboratory, 53
    Description / Table of Contents: Summary: The results of investigations on the structural changes of Greenland snow during age-hardening in the first 49 hr after ejection by a Peter snow miller from a trench 4.7 ft deep are reported, and the method of study is described. The samples of snow were taken at various distances from the trench 1, 3, 14, 25, and 49 hr after deposition, and their changes were studied as a function of time and distance from the trench. The porosity remained constant at an average of 50 ± 3%. The number of grains/cm^2 decreased with time and increased with distance from the trench because of the different speeds of sedimentation and wind sifting. The mean grain cross-section showed a similar dependence. The relative length of grain boundaries increased with time and slightly with distance from the trench, while the mean length of new grain-to-grain boundaries increased with age and decreased with distance from the trench. The mean number of adjacent grains per grain vs. relative length of grain boundaries showed a linear relation. A slight increase of new boundaries with increasing number of neighbors was also observed. Suggestions for a precise study of the age-hardening process of snow are made.
    Type of Medium: Series available for loan
    Pages: v, 15, A5 Seiten , Illustrationen
    Series Statement: Research report / Cold Regions Research and Engineering Laboratory 53
    Language: English
    Note: CONTENTS Preface Summary Methods of testing Sampling Preparation of samples Preparation of structure pictures Results Influence of time and place Porosity Number of grains/cm2 Mean grain cross section Relative length of grain boundaries (KM ratio) Mean number of adjacent grains per grain Number of new boundaries/cm 2 Mean length of new grain-to-grain boundaries Some interrelations of the structure data Structure of a 1-yr old Peter snow Suggestions for an exact study of the age-hardening process of snow References Appendix: Structure pictures
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  • 6
    Series available for loan
    Series available for loan
    Wilmette, Ill. : Snow Ice and Permafrost Research Establishment, Corps of Engineers, U.S. Army
    Associated volumes
    Call number: ZSP-202-56
    In: Research report / Cold Regions Research and Engineering Laboratory, 56
    Description / Table of Contents: Summary: The results of laboratory creep tests in a shear apparatus at -5°C on 2 x2 x 3/8 in. samples of commercial ice, artificial single crystals, and 6 types of ice from the Greenland Ice Cap, at shear stresses of about 0.5-3 kg/cm^2 are reported. Some uniaxial tests were made at stresses from 6-28 kg/cm^2 to supplement the shear tests. Creep data could usually be represented approximately by one or more linear sections on a log-deformation vs log-time plot. The linear sections of the double logarithmic curve imply a creep curve of the form ε=ct^m where ε is the strain. For all samples tested, except single crystals sheared in easy glide, m averaged 0. 5 for shear deformations up to about 1%, and approached unity for more deformation. For single ice crystals oriented for easy glide, m averaged 1.7, implying a strain softening. Single crystals oriented for hard glide behaved similarly to polycrystals, indicating a rate-controlling process such as dislocation climb. For all but single easy-glide crystals, the minimum creep rate was tangent to the deformation curve at the end of the experiment. Creep rates for single easy-glide crystals were several hundred times larger than for the other crystals, the flow laws being similar.
    Type of Medium: Series available for loan
    Pages: iv, 7 Seiten , Illustrationen
    Series Statement: Research report / Cold Regions Research and Engineering Laboratory 56
    Language: English
    Note: CONTENTS Preface Summary Introduction Types of ice Experiments Results Creep curves Flow law References
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  • 7
    Series available for loan
    Series available for loan
    Wilmette, Ill. : Snow Ice and Permafrost Research Establishment, Corps of Engineers, U.S. Army
    Associated volumes
    Call number: ZSP-202-55
    In: Research report / Cold Regions Research and Engineering Laboratory, 55
    Description / Table of Contents: Summary: Experiments were performed to investigate the processes involved in the formation of sorted patterns which occur naturally in unconsolidated sandy gravel deposits covering the edge of the ice cap southeast of Thule, northwest Greenland. Four different glacier ice surfaces were covered with various thicknesses of sandy gravel in order to observe the effect of differential melting on the formation of sorted patterns. The different stages of pattern formation were recorded by photographs taken at 7-day intervals. A thin gravel cover of 2 in. allowed more rapid melting than did a cover of 6 in., with the result that depressions and mounds were formed. Coarse particles were segregated in the depressions by natural sorting of the various particle sizes when set in motion by differential melting and resulting uneven collapse of the gravel cover. The sorting produced well-developed stone rings in three of the areas, caused directly by the differential insulation provided by the gravel cover. In the fourth area a uniform gravel cover over a smooth ice surface produced no sorted nets, although a poorly developed stone stripe was formed in a melt-stream channel. A stone stripe was also formed in a stream channel cut into the ice along the edge of the test area. This stripe was composed of coarse particles which rolled down from the better insulated heights of the test area. It is therefore possible that sorted nets and stripes occurring naturally in the moraine deposits on the edge of the ice cap could have been formed by mechanical sorting induced by differential melting of the ice under a non-uniform layer of sandy gravel.
    Type of Medium: Series available for loan
    Pages: iv, 15 Seiten , Illustrationen
    Series Statement: Research report / Cold Regions Research and Engineering Laboratory 55
    Language: English
    Note: CONTENTS Preface Summary Introduction Procedure Preparation of test plots Measurements of ice and gravel surfaces Composition of the gravel covering Results Sorting in a smooth layer of sandy gravel over an uneven ice surface Sorting in a uniform layer of sandy gravel over depressions in the ice surface Sorting in a uniform layer of sandy gravel over a uniform ice surface Sorting in a non-uniform layer of sandy gravel over a uniform ice surface Discussion and recommendations Conclusions References
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  • 8
    Series available for loan
    Series available for loan
    Wilmette, Ill. : Snow Ice and Permafrost Research Establishment, Corps of Engineers, U.S. Army
    Associated volumes
    Call number: ZSP-202-43
    In: Research report / Cold Regions Research and Engineering Laboratory, 43
    Description / Table of Contents: Summary: Charts of mean annual air temperature and precipitation over the ice cap are constructed on the basis of snow-profile studies at 8 locations, data collected for several years after 1953 at two U.S. Air Force weather stations, and records from expeditions since 1930. The warming trend in the Arctic appears to have occurred to a lesser degree on the ice cap, possibly because of the effect of the snow cover. The lowest mean annual temperature in South Greenland is estimated to occur within the area bounded by the 2500 m contour and the -18°C isotherm; mean annual temperature at 2700 is estimated as -20.9°C. In North Greenland, the mean annual temperature at 1700 m is estimated at -22°C. The presence of ice glands in the snow and daily max summer temperatures, estimated from records of coastal stations, indicate a potentially high incidence of melting at about 1300 m elevation and some melting at 1700 m in North Greenland, and melting up to 2700 m in the South. Annual accumulation is 2-3 times as great at 2500 m on the west side of the ice cap as at the crest. South of 66°N, precipitation may be about twice as great on the east side of the crest as in the west.
    Type of Medium: Series available for loan
    Pages: iv, 9 Seiten , Illustrationen
    Series Statement: Research report / Cold Regions Research and Engineering Laboratory 43
    Language: English
    Note: CONTENTS Preface Summary Introduction Derivation of mean annual air temperature data Annual accumulation References
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  • 9
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    Series available for loan
    Wilmette, Ill. : Snow Ice and Permafrost Research Establishment, Corps of Engineers, U.S. Army
    Associated volumes
    Call number: ZSP-202-32
    In: Research report / Cold Regions Research and Engineering Laboratory, 32
    Description / Table of Contents: Summary: Apparatus was built for deforming ice crystals under hydrostatic pressures up to 350 atmospheres. Single crystals were placed in the mounts in such a way that the deformation occurred by gliding on the basal glide plane. It was found that the shear strain rate increased as the pressure was increased at constant temperature, but that the rate is practically independent of hydrostatic pressure when the difference between the ice temperature and the melting point is kept constant.
    Type of Medium: Series available for loan
    Pages: iv, 7 Seiten , Illustrationen
    Series Statement: Research report / Cold Regions Research and Engineering Laboratory 32
    Language: English
    Note: CONTENTS Preface Summary Introduction Test apparatus and experimental procedures Experimental results Conclusions References
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  • 10
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    Series available for loan
    Wilmette, Ill. : Snow Ice and Permafrost Research Establishment, Corps of Engineers, U.S. Army
    Associated volumes
    Call number: ZSP-202-33
    In: Research report / Cold Regions Research and Engineering Laboratory, 33
    Description / Table of Contents: Summary: A series of deformation measurements have been selected for preliminary studies on the plasticity of Greenland glacier ice. The measurements to be reported on were obtained in the Red Rock and TUTO tunnels in Northwest Greenland. Both tunnels were excavated during the summer of 1955 with some additional work done during the summer of 1956. Deformation measurements made up to the end of the 1956 summer season, therefore, are of limited reliability, but certain trends appearing in these data seem worth reporting. The topics discussed are (1) the shearing of an initially vertical peg system at Red Rock, (2) the deformation of core holes at TUTO, and (3) tunnel closure at both sites. These data are analyzed on the basis of laminar flow of the Nye type and certain conclusions are derived.
    Type of Medium: Series available for loan
    Pages: 6 Seiten , Illustrationen
    Series Statement: Research report / Cold Regions Research and Engineering Laboratory 33
    Language: English
    Note: CONTENTS Introduction Experimental Analysis The shear of glaciers Tunnel closure Conclusions References
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