Volume 31, Issue 1 (January 2008)

    Reproducibility of Direct Shear Tests Conducted on Granular Backfill Materials

    (Received 26 October 2006; accepted 17 June 2007)

    Published Online: 2007

    CODEN: GTJOAD

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    Abstract

    Intra-laboratory and inter-laboratory testing was conducted to assess the bias, repeatability, and reproducibility of the shear strength of compacted granular backfill materials tested in direct shear using AASHTO T 236. Inter-laboratory testing was conducted by ten laboratories using four granular backfill materials. Triaxial compression tests were also conducted on the granular backfill materials to establish a reference friction angle (ϕ) for computing bias. Comparison of failure envelopes and friction angles from the intra-laboratory study showed that the test method is highly repeatable (ϕ±0.1°) when conducted in a single laboratory by a single operator using the same equipment. In contrast, data from the inter-laboratory study showed high variability in the failure envelopes and friction angles, with ϕ varying by as much as 18.2° for a given backfill. Analysis of the data from the inter-laboratory study showed that the reproducibility of direct shear tests on granular backfill is 8.8°. The bias in ϕ is −2.5° when area corrections are not applied and −1.5° when area corrections are applied.


    Author Information:

    Bareither, Christopher A.
    Graduate Research Assistant, Geological Engineering, University of Wisconsin-Madison, Madison, WI

    Benson, Craig H.
    Professor and Kellet Fellow, Geological Engineering, University of Wisconsin-Madison, Madison, WI

    Edil, Tuncer B.
    Professor and Chairman, Geological Engineering, University of Wisconsin-Madison, Madison, WI


    Stock #: GTJ100878

    ISSN: 0149-6115

    DOI: 10.1520/GTJ100878

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    Author
    Title Reproducibility of Direct Shear Tests Conducted on Granular Backfill Materials
    Symposium , 0000-00-00
    Committee D18