STP1014: Interpretation of the Field Vane Test in Terms of In-Situ and Yield Stresses

    Becker, DE
    Associate, Golder Associates, Mississauga, Ontario

    Crooks, JHA
    Principal and associate, Golder Associates, Calgary, Alberta

    Been, K
    Principal and associate, Golder Associates, Calgary, Alberta

    Pages: 17    Published: Jan 1988


    Abstract

    Interpretation of undrained shear strength data requires knowledge of the effective stress regime that is controlling the strength on the failure surface. Approximately 90% of the total resistance measured by the standard vane is provided by the vertical circumscribed failure surface. Consequently, vane test results are dominated by the strength mobilized on the vertical plane. Therefore, it is the horizontal in-situ effective and yield stresses that predominantly control the vane shear strength. Yet, to date, vane strength correlations have been considered in terms of vertical stresses only.

    This paper discusses an interpretation for the field vane test within generalized state concepts. State can be characterized by an overconsolidation ratio that accounts for both vertical and horizontal stresses. The controlling influence of the in-situ effective and yield stresses on measured field vane strength is demonstrated using data for 14 clay deposits. Vane strength normalized with respect to in-situ effective stresses are correlated with overconsolidation ratio to confirm the generalized state concepts and importance of accounting for horizontal stresses. Normalized vane strength correlations are compared to normalized strength ratios back-analyzed from field failures. It is shown that strength ratios normalized using vertical preconsolidation pressures are not sufficiently refined to provide a good basis for comparison. Strength ratios based on horizontal yield stresses provide a more rational basis for comparison.

    Keywords:

    vane, normalized shear strength, state, overconsolidation ratio, in-situ horizontal stresses, yield, correlations, correction factors


    Paper ID: STP10322S

    Committee/Subcommittee: D18.02

    DOI: 10.1520/STP10322S


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