A comprehensive investigation of the shear strength of Beaumont clay was undertaken to support the design of a new off-channel reservoir in Texas. Testing of intact, remolded, and compacted clay provided the basis for establishing soil shear strength parameters used in conducting slope stability analyses of the embankment dam. This paper focuses on characterization of the shear strength of remolded and compacted clay. Remolded clay was tested using direct shear, torsional ring shear, and consolidated-undrained triaxial methods. Compacted clay was tested using unconsolidated-undrained and consolidated-undrained triaxial methods. Specific topics of the paper include: (1) comparison of fully softened strength measurements from direct shear, torsional ring shear, and consolidated-undrained triaxial testing methods; (2) comparison of fully softened strength measurements with empirical correlations; (3) factors affecting the undrained strength of compacted clay from unconsolidated-undrained triaxial testing; and (4) summary of drained and undrained shear strength parameters of compacted clay for consolidated-undrained conditions. The laboratory testing addresses common misconceptions about the actual factors affecting shear strength characteristics of normally consolidated and compacted clay. Undrained strength of clay is primarily related to the void ratio during shearing (and degree of saturation for compacted clay), whereas drained strength parameters are not significantly affected by void ratio or compaction conditions.
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