Cyclic Simple Shear Behavior of Fine Grained Soils

Consolidated, constant volume (CCV), cyclic laboratory shear tests were performed on marine clay soils. The Norwegian Geotechnical Institute (NGI) direct simple shear device, modified for cyclic loading (square wave) capabilities, was used for these tests. Two clays were investigated; a natural undisturbed Gulf of Mexico clay and a reconstituted Pacific Illite. The cyclic shear tests were performed with two way loading (complete stress reversal). Models are presented to predict the pore pressure behavior during a cyclic test, or to predict the strain or pore pressure behavior of tests with varying cyclic shear stress levels. A unique relationship between shear strain and pore pressure for the tests in this investigation is presented