Journal Published Online: 14 February 2022
Volume 45, Issue 3

Development and Evaluation of Preconditioning Protocols for Sand Specimens in Constant-Volume Cyclic Direct Simple Shear Tests

CODEN: GTJODJ

Abstract

Textured platens are often used to improve the transfer of shear stresses from the platens to the soil specimen during direct simple shear (DSS) tests. However, constant-volume DSS tests when textured platens are used can be affected by inadequate engagement of the soil at the platen-soil interface, leading to large reductions in the vertical stress at the start of shearing. The application of a preconditioning sequence involving small-strain drained cycles prior to constant-volume shearing can improve engagement at the platen-soil interface, but when excessively implemented, it can also have adverse effects on the measured soil behavior (e.g., strength, stiffness). A series of constant-volume cyclic DSS tests preceded by different preconditioning sequences was performed to evaluate the effect of preconditioning on the engagement of sand specimens at the platen-soil interface and the stress-strain response of these specimens. Results showed that textured platens that are properly engaged with sand specimens can reduce slippage at the platen-soil interface. This engagement can be achieved by applying a limited number of small-strain drained cycles at a low vertical stress while still obtaining representative soil behavior during the subsequent equivalent undrained constant-volume cyclic loading. Although the preconditioning protocol presented herein is specific to the testing equipment and materials considered, similar procedures may be adopted to develop preconditioning protocols for other soils, platens, and testing devices.

Author Information

Humire, Francisco
Department of Civil and Environmental Engineering, University of California, Davis, Davis, CA, USA
Lee, Minyong
Department of Civil and Environmental Engineering, University of Washington, Seattle, WA, USA
Ziotopoulou, Katerina
Department of Civil and Environmental Engineering, University of California, Davis, Davis, CA, USA
Gomez, Michael G.
Department of Civil and Environmental Engineering, University of Washington, Seattle, WA, USA
DeJong, Jason T.
Department of Civil and Environmental Engineering, University of California, Davis, Davis, CA, USA
Pages: 13
Price: $25.00
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Stock #: GTJ20210028
ISSN: 0149-6115
DOI: 10.1520/GTJ20210028