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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
    Series available for loan
    Series available for loan
    Hanover, NH : U. S. Army Cold Regions Research and Engineering Laboratory
    Associated volumes
    In: CRREL Report, 93-9
    Description / Table of Contents: Traction on winter surfaces was measured using three test vehicles, each designed to measure traction for a different purpose: vehicle mobility research (CRREL Instrumented Vehicle), commercial tire testing (Uniroyal- Goodrich traction tester), and airport runway safety (Saab friction tester). The traction measured with each method is comparable, but there are systematic differences due to the effects of the surface material and the test and analysis technique. This comparison serves as the fundamental basis for collaboration between the various traction testing communities and illustrates the need for well documented test procedures and data analysis as a standard for traction testing and evaluation.
    Type of Medium: Series available for loan
    Pages: iii, 21 Seiten , Illustrationen
    Series Statement: CRREL Report 93-9
    Language: English
    Branch Library: AWI Library
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  • 3
    Call number: ZSP-201-92/17
    In: CRREL Report, 92-17
    Description / Table of Contents: The CRREL Instrumented Vehicle (CIV), shear annulus, direct shear, andtriaxial compression devices were used to characterize the strength ofthawed and thawing soil. These strength values can be used in simpletraction models to predict the tractive performance of vehicles. Strength was evaluated in terms of the parameters c' and Φ' based on the Mohr-Coulomb failure criterion. It is proposed here that an instrumented vehicle is best suited for terrain characterization for mobility studies because the conditions created by a tire slipping on a soil surface are exactly duplicated. The c' and Φ' values from the shear annulus were found to overpredict traction because of the low normal stress applied by the annulus and the curved nature of the failure envelope. Of all the tests, the direct shear test yielded the highest Φ' value, most likely because the test was run at a slow deformation rate under drained conditions. The triaxial test results were the most similar to those from the vehicle. All test methods show Φ' increasingwith soil moisture up to the liquid limit of the soil and then decreasing. As measured with the vehicle, was also found to be strongly influenced by the thaw depth.
    Type of Medium: Series available for loan
    Pages: 17 Seiten , Illustrationen
    Series Statement: CRREL Report 92-17
    Language: English
    Note: CONTENTS Introduction Objective Background Strength measurement techniques Triaxial compression Direct shear Shear annulus device CRREL Instrumented Vehicle Discussion Comparison of methods Influence of soil conditions Traction prediction Conclusions References Abstract
    Location: AWI Archive
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    ISSN: 1745-6592
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: On-site analysis of trichloroethylene (TCE) in aqueous samples by head- space sample preparation and gas chromatography (HS/GC) provides for quick and precise concentration estimates. This analytical approach is well suited for the on-site determination of volatile organic compounds (VOCs) in a variety of sample matrices, including ground water and saturated and unsatured soils. For these reasons, HS/GC can be used to establish analyte concentrations on a near real time basis to help select appropriate casing material during monitoring well installation. This application and the collection of multiple well samples during sampling events facilitates the hydrogeological site interpretation and the formulation of remediation strategies.
    Type of Medium: Electronic Resource
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