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  • 1
    Schriftenreihen ausleihbar
    Schriftenreihen ausleihbar
    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
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    Signatur: ZSP-201-83/25
    In: CRREL Report, 83-25
    Beschreibung / Inhaltsverzeichnis: Ice action on two cylindrical and conical structures, located side by side, was investigated in a small-scale experimental study to determine the interference on the ice forces generated during ice-structure interaction. The proximity of the two structures changes the mode of ice failure, the magnitude and direction of ice forces on the individual structure, and the dominant frequency of ice force variations. Interference effects were determined by comparing the experimental results of tests at different structure spacings.
    Materialart: Schriftenreihen ausleihbar
    Seiten: 42 Seiten , Illustrationen
    Serie: CRREL Report 83-25
    Sprache: Englisch
    Anmerkung: CONTENTS Abstract Preface Nomenclature Introduction Experimental setup and procedure Results and discussion Cylindrical structures Conical structures Conclusions Literature cited Appendix A: Relationship between flexural strength and in-situ unconfined compressive strength Appendix B: Test data
    Standort: AWI Archiv
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  • 2
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    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
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    Signatur: ZSP-201-83/26
    In: CRREL Report, 83-26
    Beschreibung / Inhaltsverzeichnis: Ice accreted on high-speed rotors operating in supercooled fog can be thrown off by centrifugal force, creating severe unbalance and dangerous projectiles. A simple force balance analysis indicates that the strength of accreted ice and its adhesive strength can be obtained by measuring the thickness of the accretion, the location of the separation, the rotor speed, and the density. Such an analysis was applied to field and laboratory observations of self-shedding events. The results agree reasonably well with other observations.
    Materialart: Schriftenreihen ausleihbar
    Seiten: 13 Seiten , Illustrationen
    Serie: CRREL Report 83-26
    Sprache: Englisch
    Standort: AWI Archiv
    Zweigbibliothek: AWI Bibliothek
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  • 3
    Signatur: ZSP-201-83/24
    In: CRREL Report, 83-24
    Beschreibung / Inhaltsverzeichnis: Secondary recovery of oil at Prudhoe Bay, Alaska, will involve transporting large quantities of seawater in elevated pipelines across tundra for injection into oil-bearing rock strata. The possibility of a pipeline rupture raises questions concerning the effects of seawater on tundra vegetation and soils. To evaluate the relative sensitivities of different plant communities to seawater, eight sites representing the range of vegetation types along the pipeline route were treated with single, saturating applications of seawater during the summer of 1980. Within a month of the treatment 30 of 37 taxa of shrubs and forbs in the experimental plots developed clear symptoms of stress, while none of the 14 graminoid taxa showed apparent adverse affects. Live vascular plant cover was thus reduced by 89 and 91% in the two dry sites and by 54, 74 and 83% in the three moist sites, respectively. Live(green) bryophyte cover was markedly reduced in the moist experimental sites in 1981. Bryophytes in all but one of the wet-site experimental plots were apparently unaffected by the seawater treatment. Two species of foliose lichens treated with seawater showed marked deterioration in 1981. All other lichen taxa were apparently unaffected by the seawater treatment. The absorption and retention of salts by the soil is inversely related to the soil moisture regime. In the wet sites, conductivities approached prespill levels within about 30 days. In such sites, spills at the experimental volumes are quickly diluted and the salts flushed from the soil. In the dry sites, on the other hand, salts are retained in the soil, apparently concentrating at or near the seasonal thaw line.
    Materialart: Schriftenreihen ausleihbar
    Seiten: 43 Seiten , Illustrationen
    Serie: CRREL Report 83-24
    Sprache: Englisch
    Anmerkung: CONTENTS Abstract Preface Introduction Methods Site selection and preparation Prespill assessment Seawater application Postspill assessment Enzyme assay and analysis of soil flora Results and discussion Soil-solution conductivities Vascular plant response Cryptogam response Site factors and plant response Soil flora and extracellular soil enzymes Limitations of this study Summary and conclusions Literature cited Appendix: Plant taxa included in this study
    Standort: AWI Archiv
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  • 4
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    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
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    Signatur: ZSP-201-82/31
    In: CRREL Report, 82-31
    Beschreibung / Inhaltsverzeichnis: Information on sea ice conditions in the Bering Strait and the icefoot formation around Fairway Rock, located in the strait, is presented. Cross-sectional profiles of Fairway Rock and the relief of the icefoot are given along with theoretical analyses of the possible forces active during icefoot formation. It is shown that the ice cover most likely fails in flexure as opposed to crushing or buckling, as the former requires less force. Field observations reveal that the Fairway Rock icefoot is massive, with ridges up to 15 m high, a seaward face only 20 degrees from vertical, and interior ridge slopes averaging 33 degrees. The icefoot is believed to be grounded and its width ranges from less than 10 to over 100 m.
    Materialart: Schriftenreihen ausleihbar
    Seiten: 44 Seiten , Illustrationen
    Serie: CRREL Report 82-31
    Sprache: Englisch
    Anmerkung: CONTENTS Abstract Preface Introduction Bering Strait Field reconnaissance Estimation of ice forces on Fairway Rock 1. Creep deformation 2. Crushing failure 3. Flexural failure 4. Forces required to form floating or grounded pressure ridges along therock or to pile ice on the beaches 5. Buckling failure Driving forces Angle of internal friction of sea ice Summary Literature cited Appendix A: April 1982 field observations at Fairway Rock
    Standort: AWI Archiv
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  • 5
    Schriftenreihen ausleihbar
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    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
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    Signatur: ZSP-201-83/4
    In: CRREL Report, 83-4
    Beschreibung / Inhaltsverzeichnis: Measurements and analysis of seasonal ice growth and decay on Post Pond, New Hampshire, for the period 1973-1982 are presented. Observations included ice thickness measurements, examination of the various ice types contributing to the ice cover, and measurements of meteorological parameters for correlation with and modeling of the ice growth process. The overall nature of ice growth and decay (ice loss) on the Post Pond has been ascertained, the seasonal variability in the timing of freeze-up and ice-out and the duration of the ice cover have been determined, and the relationship of ice growth to freezing-degree-day (deg C) records evaluated on the basis of a Stefan conduction equation modified to deal with ice sheets covered with or free of snow. Ice growth occurs predominantly by the direct freezing of lake water, but snow ice may compose as much as 50% of the ice cover in winters with higher than average snowfall. Freeze-up leading to the establishment of a stable ice cover occurs during the 4-week period from the end of November to the end of December. Maximum seasonal ice thicknesses were from 45 to 67 cm and are generally attained during the first two weeks of March; ice-out, marking the final disappearance of ice from Post Pond, usually occurs by the third week of April. The overall rate of the ice loss is three to four times that of ice growth, and is dominated initially by melting from the top. As much as 50% of the ice may be lost in this way before the onset of any bottom melting. Final dissipation of the ice cover is usually expedited by candling resulting from preferential melting and disintegration of the ice at crystal boundaries.
    Materialart: Schriftenreihen ausleihbar
    Seiten: iv, 30 Seiten , Illustrationen
    Serie: CRREL Report 83-4
    Sprache: Englisch
    Anmerkung: CONTENTS Abstract Preface Introduction Location of study Study methods Ice thickness Ice-cover composition Surface air temperatures Freeze-up and ice-out characteristics Results and discussion Ice-growth record Freezing-degree-day records Ice-growth predictions Summary and conclusions Literature cited Appendix A: Ice-growth records Appendix B: Measured and computed ice-growth curves
    Standort: AWI Archiv
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  • 6
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    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
    Dazugehörige Bände
    Signatur: ZSP-201-83/1
    In: CRREL Report, 83-1
    Beschreibung / Inhaltsverzeichnis: Roof snow load case studies gathered throughout the United States over a three-year period are analyzed. The objective of the analysis is to determine a relationship between the snow load on the ground and the corresponding uniform snow load on flat and sloped roofs. The main parameters considered are the thermal characteristics of the roof, the roof slope and the exposure of the structure. Exposure has the strongest effect on the ratio of ground to roof snow loads. Comparisons are made with existing and proposed building codes and standards.
    Materialart: Schriftenreihen ausleihbar
    Seiten: iv, 47 Seiten , Illustrationen
    Serie: CRREL Report 83-1
    Sprache: Englisch
    Anmerkung: CONTENTS Abstract Preface Metric conversion table Introduction Data base Conversion factor Ground load effects Exposure effects Thermal effects Slope effects Expected value relationship Comparison with existing codes and standards Comparison with relationships proposed in new ANSI standard Summary and conclusions Literature cited Appendix A. Roof snow load case history reports Appendix B. Roofs in the snow load case study data base Appendix C. Ground and roof snow load data Appendix D. Conversion factors from the 1982 ANSI standard
    Standort: AWI Archiv
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  • 7
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    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
    Dazugehörige Bände
    Signatur: ZSP-201-83/30
    In: CRREL Report, 83-30
    Beschreibung / Inhaltsverzeichnis: Ice sheets are formed and retained in several ways in nature, and an understanding of these factors is needed before most structures can be successfully applied. Many ice sheet retention structures float and are somewhat flexible; others are fixed and rigid or semirigid. An example of the former is the Lake Erie ice boom and of the latter, the Montreal ice control structure. Ice sheet retention technology is changing. The use of timber cribs is gradually but not totally giving way to sheet steel pilings and concrete cells. New structures and applications are being tried but with caution. Ice-hydraulic analyses are helpful in predicting the effects of structures and channel modifications on ice cover formation and retention. Often, varying the flow rate in a particular system at the proper time will make the difference between whether a structure will or will not retain ice. The structure, however, invariably adds reliability to the sheet ice retention process.
    Materialart: Schriftenreihen ausleihbar
    Seiten: iv, 39 Seiten , Illustrationen , 1 Beilage
    Serie: CRREL Report 83-30
    Sprache: Englisch
    Anmerkung: Contents Abstract Preface Introduction Natural ice sheets Choosing an ice control structure Flexible structures Ice booms Frazil collector lines Fence booms Rigid or semirigid structures Pier-mounted booms Stone groins Artificial islands Removable gravity structures Timber cribs Weirs Pilings and dolphins Structures built for other purposes Hydroelectric dams Wicket dams Light piers and towers Bridge piers Breakwaters Ice control not using Structures Channel improvements Ice sheet tying Ice sheet bridges Conclusions Literature cited Appendix A: Ice control structure
    Standort: AWI Archiv
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  • 8
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    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
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    Signatur: ZSP-201-84/26
    In: CRREL Report, 84-26
    Beschreibung / Inhaltsverzeichnis: Observations of shore ice pile-up and ride-up along the Alaska Beaufort Sea coast in 1983 and 1984 are presented. New information on historical accounts of onshore ice movement, uncovered since publication of Part I in this series, is reported. An account is given of ice overtopping a concrete caisson exploration island in the Canadian Beaufort Sea.
    Materialart: Schriftenreihen ausleihbar
    Seiten: iii, 33 Seiten , Illustrationen
    Serie: CRREL Report 84-26
    Sprache: Englisch
    Anmerkung: CONTENTS Abstract Preface Introduction Observations Discussion Literature cited Appendix A: Site location maps
    Standort: AWI Archiv
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  • 9
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    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
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    Signatur: ZSP-201-80/9
    In: CRREL Report, 80-9
    Beschreibung / Inhaltsverzeichnis: Explosive cratering tests were conducted in seasonally frozen and thawed gravel at Ft. Richardson near Anchorage, Alaska, and in seasonallly frozen and thawed silt overlying permafrost and in silt permafrost at Ft. Wainwright near Fairbanks, Alaska. Explosive charge weights ranged from 26 to 3120 lb and charge burial depths ranged from about 3 to 40 ft. The cube root of the charge weight scaling was used to determine maximum scaled crater dimensions and optimum scaled depth of burial of the charge. Test results for frozen and thawed gravel were essentially the same because of the low moisture content and the relatively shallow depth of freezing (5 to 6 ft). The optimum depth of burial of the charge for maximizing the apparent radius and depth and the true radius was about 1.8 times the cube root of the charge weight for both the frozen and thawed conditions. In seasonally frozen silt overlying a talik and silt permafrost the maximum scaled crater dimensions and optimum scaled burial depths of the charge were smaller than for the thawed condition except for the true crater dimensions. The channeling of energy in the talik produces maximum crater dimensions and an optimum burial depth for the true crater that is larger than for the thawed condition. The results for the homogeneous silt permafrost were very similar to the frozen gravel results with much smaller maximum crater dimensions and smaller optimum charge burial depths than for the thawed silt overlying permafrost.
    Materialart: Schriftenreihen ausleihbar
    Seiten: v, 21 Seiten , Illustrationen
    Serie: CRREL Report 80-9
    Sprache: Englisch
    Anmerkung: CONTENTS Abstract Preface Metric conversion table Introduction Test sites Test procedures and materials Analysis of test data Mobility tests Conclusions Literature cited
    Standort: AWI Archiv
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  • 10
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    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
    Dazugehörige Bände
    Signatur: ZSP-201-80/8
    In: CRREL Report, 80-8
    Beschreibung / Inhaltsverzeichnis: This report presents the results of the tests on the new U.S. Coast Guard 140-ft icebreaker Katmai Bay (WTGB-101) in the level plate ice and brash ice in Whitefish Bay and the St. Marys River. The results indicate that the vessel can penetrate 22 in. of level freshwater ice with 2-3 in. of snow cover. It can also penetrate up to 48 in. of brash ice in a continuous mode and at least 30 in. of plate ice by backing and ramming. The installed bubbler system decreased the required power of the vessel from 10 to 30% in brash ice and 25 to 35% in level ice. The low friction coating appears to be effective in decreasing the friction factor when it remains intact; when it peels off it appears to make conditions worse than plain paint. An average dynamic friction factor of 0.15 could be used over the entire hull for these tests.
    Materialart: Schriftenreihen ausleihbar
    Seiten: iv, 28 Seiten , Illustrationen
    Serie: CRREL Report 80-8
    Sprache: Englisch
    Anmerkung: CONTENTS Abstract Preface Metric conversion table Introduction Roughness and friction measurements Level plate ice performance Brash ice performance Ramming icebreaking performance Analysis of the data Propulsion efficiency in ice Regression analysis Conclusions and recommendations Literature cited
    Standort: AWI Archiv
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