STP740

    Shearing Behavior of Compacted Clay after Saturation

    Published: Jan 1981


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    Abstract

    The purpose of this investigation was to ascertain the relationships among the compaction conditions (dry density moisture content and compaction energy) and the shearing behavior after saturation for a kneading compacted, highly plastic clay. The effective stress strength and pore pressure parameters were evaluated for various compaction conditions through the performance of consolidated undrained triaxial tests with pore water pressure measurement (CU¯) at a constant rate of strain. Long-term environmental effects were approximated prior to shear with backpressure saturation followed by consolidation to an isotropic state of stress representing the vertical load applied by succeeding lifts of an embankment.

    The results of the testing program showed that the effective stress friction angle is relatively invariate for the range of compaction conditions investigated. The magnitude and range of variation of the measured values of the effective stress strength intercept were small. However, the volumetric strain upon saturation and the values of Skempton's A-parameter at failure were strongly affected by compaction conditions. Accordingly, the undrained strength of the compacted clay was significantly altered by the details of compaction.

    Statistical analyses were performed to construct prediction equations based on the compaction variables for percent volume change due to saturation and consolidation. Skempton's A-parameter at failure, and the effective stress strength intercept. The equations obtained for percent volume change due to saturation and consolidation and Skempton's A-parameter at failure indicate that as-compacted dry density, initial degree of saturation, and consolidation pressure are the critical variables influencing behavior. The equation for the effective stress strength intercept indicates that initial void ratio and compaction moisture content are the significant variables. These equations will aid efforts to predict and modify the long-term shear behavior of compacted cohesive soils.

    Keywords:

    compaction, shear strength, effective stress, saturation, pore pressure parameters, statistical analyses


    Author Information:

    Lovell, CW
    Professor, School of Civil Engineering, Purdue University, W. Lafayette, Ind.

    Johnson, JM
    Geotechnical engineer, Klohn-Leonoff Consultants, Inc., Denver, Colo.


    Paper ID: STP28757S

    Committee/Subcommittee: D18.05

    DOI: 10.1520/STP28757S


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