A Numerical View into Direct Shear Specimen Size Effects

    Volume 30, Issue 6 (November 2007)

    ISSN: 0149-6115

    CODEN: GTJOAD

    Published Online: 22 May 2007

    Page Count: 5


    Jacobson, Douglas E.
    Graduate Research Assistant and Assistant Professor, respectively, Department of Civil and Environmental Engineering, San Diego State University, San Diego, CA

    Valdes, Julio R.
    Graduate Research Assistant and Assistant Professor, respectively, Department of Civil and Environmental Engineering, San Diego State University, San Diego, CA

    Evans, T. Matthew
    Assistant Professor, Department of Civil, Construction, and Environmental Engineering, North Carolina State University, Raleigh, NC

    (Received 21 November 2006; accepted 19 March 2007)

    Abstract

    The ASTM D 3080-04 standard, Standard Test Method for Direct Shear Test of Soils under Consolidated Drained Conditions, indicates that the direct shear test specimen width L must be at least ten times larger than the largest particle in the specimen, L/d ≥ 10. The results documented in this note provide visual insight into specimen size and boundary effects through discrete element simulations conducted with numerical specimens ranging in size from L/d = 6.5 to L/d = 177. Particle translation data indicate that in the tested configuration, localized shear zones located far from the specimen boundaries develop only when the specimen size is L/d > 58. The results provide a description of the microstructure evolution during shearing and suggest that the ASTM specimen size criterion may be inappropriate when localized shear banding in uniform granular materials is sought.


    Paper ID: GTJ100923

    DOI: 10.1520/GTJ100923

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    Author
    Title A Numerical View into Direct Shear Specimen Size Effects
    Symposium , 0000-00-00
    Committee D18