Volume 23, Issue 3 (September 2000)

    Assessment of Localized Deformations in Sand Using X-Ray Computed Tomography

    (Received 12 November 1998; accepted 19 January 2000)

    CODEN: GTJOAD

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    Abstract

    The internal fabric and localized deformation patterns of triaxial sand specimens were investigated using computed tomography (CT). Three displacement-controlled, conventional, drained axisymmetric (triaxial) experiments were conducted on dry Ottawa sand specimens at very low effective confining stresses (0.05, 0.52, and 1.30 kPa) in a microgravity environment aboard the Space Shuttle during the NASA STS-79 mission. CT scanning was performed on these flight specimens, as well as on an uncompressed specimen and a specimen tested in a terrestrial laboratory at 1.30 kPa effective confining stress. CT demonstrated high accuracy in detecting specimen inhomogeneity and localization patterns. Formation of deformation patters is dependent on the effective confining stress and gravity. Multiple symmetrical radial shear bands were observed in the specimens tested in a microgravity environment. In the axial direction, two major conical surfaces were developed. Nonsymmetrical spatial deformation was observed in the 1-G specimen. Analysis tools were developed to quantify the spatial density change. Void ratio variation within and outside the shear bands is calculated and discussed.


    Author Information:

    Alshibli, KA
    Assistant research professor, University of Alabama, Huntsville, Huntsville, AL

    Sture, S
    Professor, University of Colorado at Boulder, Boulder, CO

    Costes, NC
    Adjunct professor, University of Colorado at Boulder, Huntsville, AL

    Frank, ML
    Environmental engineer, Reisz Engineering, Huntsville, AL

    Lankton, MR
    Program manager, University of Colorado at Boulder, Boulder, CO

    Batiste, SN
    Graduate student, University of Colorado at Boulder, Boulder, CO

    Swanson, RA
    Research Associate, University of Colorado at Boulder, Boulder, CO


    Stock #: GTJ11051J

    ISSN: 0149-6115

    DOI: 10.1520/GTJ11051J

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    Author
    Title Assessment of Localized Deformations in Sand Using X-Ray Computed Tomography
    Symposium , 0000-00-00
    Committee D18