STP977: Triaxial Testing of Weak Rocks Including the Use of Triaxial Extension Tests

    Millar, PJ
    Geomechanics engineer and senior technical officer, Ministry of Works and Development, Wellington,

    Murray, DR
    Geomechanics engineer and senior technical officer, Ministry of Works and Development, Wellington,

    Pages: 11    Published: Jan 1988


    Abstract

    The strength parameters of New Zealand Tertiary weak rocks are found to be intermediate between soil and rock. The nonlinear strength envelopes of these materials for the range of stresses encountered in engineering structures mean that the strength parameters cannot be adequately defined using standard triaxial compression tests.

    The strength properties can be established at low stress levels by the triaxial extension test which allows tensile stresses to be developed in the neck of truncated specimens. At high stress levels a high stress triaxial cell is used with confining pressures up to 15 MPa.

    Keywords:

    triaxial compression, triaxial extension, high stress, nonlinear envelopes, weak rock


    Paper ID: STP29088S

    Committee/Subcommittee: D18.05

    DOI: 10.1520/STP29088S


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