Comparison of direct simple shear confinement methods on clay and silt specimens.

Seth T McGuire, University of Rhode Island

Abstract

ASTM D2435 (2000) allows for both Teflon coated stacked rings and wire reinforced membranes to be used as confinement methods in direct simple shear (DSS) testing of soils. Although stacked rings were developed over 50 years, wire reinforced membranes have been used almost exclusively in practice. Over the past 10 years, however, stacked rings have become more popular and are now the dominant confinement system sold and used in the United States. Despite this change, no comprehensive testing program comparing both confinement methods has been published. The objective of this thesis is to perform a laboratory testing program to compare the results of using stacked rings and wire reinforced membranes as a confining system for direct simple shear tests. Tests were performed on samples of a high plasticity clay from the Gulf of Mexico, a low plasticity organic silt from Rhode Island, and a low plasticity sensitive clay from Portland, Maine. All soils were tested using both confinement types, with the only difference being the use of stacked rings or the wire reinforced membrane. Measured values of undrained shear strength for both normally consolidated and overconsolidated samples were very similar using both confining systems. Samples confined with the wire reinforced membrane exhibited more strain softening beyond the peak strength and more vertical strain to the effective consolidation stress than samples confined with stacked rings. These results show that both confining systems can be used with confidence for determination of the undrained shear strength.^

Subject Area

Engineering, Civil|Engineering, Marine and Ocean

Recommended Citation

Seth T McGuire, "Comparison of direct simple shear confinement methods on clay and silt specimens." (2011). Dissertations and Master's Theses (Campus Access). Paper AAI1503334.
http://digitalcommons.uri.edu/dissertations/AAI1503334

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