STP1562: Boundary Effects of Gripping System on Internal Shear Strength Tests of Multi-Component Geosynthetic Clay Liners

    Tang, Xiaochao
    Research Associate, Louisiana Transportation Research Center, Louisiana State Univ., Baton Rouge, LA

    Yuan, Zehong
    Lab Manager, SGI Testing Services, LLC, Norcross, GA

    Pages: 10    Published: Jul 2013


    Abstract

    The internal shear strength of geosynthetic clay liners (GCLs) can be evaluated through direct shear testing in accordance with ASTM D6243 under a specific set of boundary conditions for a given normal stress. In order to prevent slippage at the GCL–gripping system interface and ensure an internal shear failure of the GCL, a gripping surface made of spikes 1 to 2mm tall mounted on a rigid substrate is recommended in the standard method and has been commonly used. It is recognized that certain boundary effects exist as a result of the aggressive gripping system. To improve the hydraulic performance and/or protect the bentonite core, a multi-component GCL is designed to have a thin membrane or film laminated or glued to one of the carrier geotextiles. It is necessary to investigate the boundary effect on the multi-component GCL internal shear strength tests, because the film– or membrane–geotextile interface is more prone to interference from the rough gripping surface recommended by the current standard. A series of internal shear strength tests were conducted on the same multi-component GCL product under different gripping conditions. It was found that tests using the aggressive gripping system yield a significantly higher peak shear strength of the multi-component GCL and a lower residual shear strength at large displacements.

    Keywords:

    multi-component GCL, shear strength, stability, direct shear, gripping surface, boundary effect


    Paper ID: STP156220120075

    Committee/Subcommittee: D35.04

    DOI: 10.1520/STP156220120075


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