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  • 1
    Call number: ZSP-201-90/9
    In: CRREL Report, 90-9
    Description / Table of Contents: In 1986, a mobility model was developed for predicting the traction and motion resistance of both wheeled and tracked vehicles on shallow snow, and a winter field season was dedicated to gathering mobility data for a diverse family of vehicles (including four on wheels and three tracked) to validate the model. The original version of the model, SSM 1.0, used the Mohr-Coulomb shear failure equation from soil mechanics to predict gross traction. This required input of the snow strength parameters c and ȹ. Motion resistance is predicted by calculating the amount of work done by the tire in compacting snow and only requires snow depth and density values as input snow properties. Some effort was expended in determining an easy and reliable method of obtaining snow strength established from past instrumented vehicle test results. Historically, shear annulus apparati have been used to obtain Mohr-Coulomb strength parameters. A comparison of snow strength obtained via these three methods (shear annulus, instrumented vehicle, calculated from initial density using the relationship in SSM 1.0) for individual snow covers showed no agreement. SSM 1.0 assumed that snow strength parameters for mobility prediction were a function of initial snow density; however, traction is developed in the compacted snow under the driving element, whose strength properties bore little relation to those of the initial snow. It appears that the shear strength of the compacted snow is essentially a constant for all of the vehicles and snow covers tested here. Based on this finding, a new traction algorithm was developed, resulting in the creation of a second generation model, SSM 2.0. This algorithm predicts gross traction, on the average for the vehicles tested, within 7% of the measured value. Motion resistance prediction remains unchanged in SSM 2.0. This quantity is still not predicted with a desirable level of accuracy.
    Type of Medium: Series available for loan
    Pages: v, 72 Seiten , Illustrationen
    Series Statement: CRREL Report 90-9
    Language: English
    Note: CONTENTS Preface Nomenclature Introduction Background Field experiments Test location and test sites Test vehicles Test procedures Results CIV traction and motion resistance Wheels/trackcs vehicles traction and motion resistance Shear annulus device Accuracy and limitations of data Snow conditons Analysis Determination of snow strength parameters Traction analysis Traction model predictions Resistance analysis Resistance model predictions Conclusions and recommendations Literature cited Appendix A: Shallow snow mobility model, version 1.0 Appendix B: Test vehicle data Appendix C : Selected test data Appendix D : Snow data Appendix E: Shallow snow mobility model code, version 2.0 Abstract
    Location: AWI Archive
    Branch Library: AWI Library
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  • 2
    Call number: ZSP-201-91/5
    In: CRREL Report, 91-5
    Description / Table of Contents: An analysis of the National Science Foundation's surface vehicle fleet in Antarctica is reported on here. Surface vehicle needs have been determined through interviews of vehicle users, managers and maintainers, and from direct on-site observation. An ideal grouping of vehicle categories is proposed that will address current needs and provide flexibility for the future. Ultimately, recommendations for streamlining and modernizing the NSF Antarctic vehicle fleet are made. Cargo transportation over snow was identified as being in a crisis state. Personnel movement functions for all but traversing are performed adequately at this time, although there is much room for improvement. Brands and models must be selected for some categories of recommended vehicle types. This will naturally follow a more in-depth analysis of candidates and discussions with NSF vehicle managers. A purchasing plan, including a time table, budget, and desired sequence of replacement, must then be formulated and executed.
    Type of Medium: Series available for loan
    Pages: v, 71 Seiten , Illustrationen
    Series Statement: CRREL Report 91-5
    Language: English
    Note: CONTENTS Preface Executive summary Introduction Regional divisions Zone A - rock and ice roads Zone B - local ice Zone C - traverse Zone D - ice edge Zone E - remote field site Zone F- inland station Current transportation needs in Antarctica Future transportation needs Transportation analysis Personnel transport Cargo transport Summary of analysis Recommendations for changes to U.S. vehicle fleet Conclusions and summary of findings Literature cited Appendix A: Age distribution of NSF surface vehicles Abstract
    Location: AWI Archive
    Branch Library: AWI Library
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  • 3
    In: CRREL Report, 93-11
    Description / Table of Contents: A laboratory study of the behavior of snow under shock wave loading and unloading conditions was conducted using a 200-mm-diameter gas gun to generate loading waves in snow samples with initial densities of 100 to 520 kg m-3 at temperatures of -2 to -23 deg C. Stress levels were 2 to 40 MPa. The response of snow to shock wave loading was measured as a function of distance from the impact plane using embedded stress gauges. Large impedance differences between snow and the stress gauges produced complex stress histories. A finite element model, along with a simple analytical model of the experiment, was used to interpret the stress histories. Snow deformation was not affected by initial temperature, but was found to be rate dependent. The initial density of the snow determined its pressure-deformation path. The pressure needed to compact snow to a specific final density increases with decreasing initial density. The release moduli increased nonlinearly from 50 MPa at a snow pressure of about 15 MPa to 2700 MPa at a snow pressure of about 40 MPa.
    Type of Medium: Series available for loan
    Pages: iii, 150 Seiten , Illustrationen
    Series Statement: CRREL Report 93-11
    Language: English
    Branch Library: AWI Library
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  • 4
    Publication Date: 1998-01-01
    Description: During the construction phase of the Pegasus runway on the McMurdo Ice Shelf, relatively large amounts of snow and ice were cleared to meet basic grade requirements for the runway surface. A considerable amount of material remains adjacent to the runway in two north–south extending mounds (berms). The runway was originally constructed on an experimental basis so attention was not focused on developing and executing a snow-removal/accumulation plan. After the runway was successfully constructed and supporting routine flight operations, concern developed over the possibility of snow accumulation adjacent to the berm area eventually inundating the runway. The intent of this project was to analyze snow accumulation and to recommend passive methods for removing some of the berm material and snow adjacent to the berm. We found that large quantities of excess snow could be removed by use of vortex fences which cause erosion on the leeward side of the fence. The vortex fence was designed to be portable (unlike traditional jet or blower fences) and self-orienting into the wind to allow snow removal regardless of the wind direction. The vortices generated by the fence do not dissipate rapidly, providing effective and sustained erosion.
    Print ISSN: 0260-3055
    Electronic ISSN: 1727-5644
    Topics: Geography , Geosciences
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  • 5
    Publication Date: 1998-01-01
    Description: During the construction phase of the Pegasus runway on the McMurdo Ice Shelf, relatively large amounts of snow and ice were cleared to meet basic grade requirements for the runway surface. A considerable amount of material remains adjacent to the runway in two north–south extending mounds (berms). The runway was originally constructed on an experimental basis so attention was not focused on developing and executing a snow-removal/accumulation plan. After the runway was successfully constructed and supporting routine flight operations, concern developed over the possibility of snow accumulation adjacent to the berm area eventually inundating the runway. The intent of this project was to analyze snow accumulation and to recommend passive methods for removing some of the berm material and snow adjacent to the berm. We found that large quantities of excess snow could be removed by use of vortex fences which cause erosion on the leeward side of the fence. The vortex fence was designed to be portable (unlike traditional jet or blower fences) and self-orienting into the wind to allow snow removal regardless of the wind direction. The vortices generated by the fence do not dissipate rapidly, providing effective and sustained erosion.
    Print ISSN: 0260-3055
    Electronic ISSN: 1727-5644
    Topics: Geography , Geosciences
    Location Call Number Expected Availability
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