STP977

    State-of-the-Art Paper: Triaxial Testing of Saturated Cohesive Soils

    Published: Jan 1988


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    Abstract

    The paper first covers common problems with testing equipment and procedures that cause errors in the measured properties of the soil specimen, with emphasis on consolidated-undrained (CU) and consolidated-drained (CD) triaxial tests. These problems are divided into three categories: errors that can be handled via appropriate corrections; errors that must be avoided; and potential errors that must be evaluated when selecting test procedures or interpreting measured data, the most important being the nonuniform stresses and strains caused by frictional end caps. The paper then assesses the use of triaxial testing in practice to predict undrained stability and deformations for saturated cohesive deposits. Based on considerations of strain rate effects, soil anisotropy, disturbance from tube sampling, and results from case histories of failures, the authors make four recommendations. 1. UU compression tests should not be used as the principal means of estimating in situ undrained strengths because the values can be either significantly too high or too low. 2. CIU compression tests have little value because the measured undrained strength will be unsafe for stability analyses, and the stress-strain data do not simulate in situ behavior. 3. Therefore, more reliance should be placed on CKoU compression and extension tests, which would be aided by the availability of more reliable and less expensive automated “stress path” triaxial cells. 4. Oedometer tests should always be conducted to ascertain the stress history of the deposit.

    Keywords:

    triaxial test, cohesive soils, laboratory testing equipment, testing procedures, corrections, testing errors, undrained strength, anisotropy, sample disturbance, strain rate, stress-strain


    Author Information:

    Germaine, JT
    Lecturer and director of the geotechnical laboratory and professor of civil engineering, Department of Civil Engineering, Massachusetts Institute of Technology, Cambridge, MA

    Ladd, CC
    Lecturer and director of the geotechnical laboratory and professor of civil engineering, Department of Civil Engineering, Massachusetts Institute of Technology, Cambridge, MA


    Paper ID: STP29091S

    Committee/Subcommittee: D18.05

    DOI: 10.1520/STP29091S


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