Response of normally consolidated kaolin clay under irregular cyclic loading and comparison with predictions from the accumulation procedure

The accumulation procedure on contour diagrams of shear strain is used in geotechnical design to account for the effect of cyclic loading on offshore foundations. In this paper, contour diagrams of maximum shear strain are presented based on a series of stress-controlled, symmetrical and non-symmetrical, cyclic direct simple shear tests on normally consolidated kaolin clay that can be used to re-examine the extensive database of model testing in kaolin clay. It is shown that failure under non-symmetrical cyclic loading can be defined at a higher maximum shear strain than under symmetrical loading, offering potential opportunities for reducing foundation sizes for structures that are less sensitive to displacement. Staged tests with parcels of uniform amplitudes have also been performed to compare the measured shear strains with the values predicted by the accumulation procedure. It is shown that the accumulation procedure predicts the strain measured in the symmetrical staged tests well, but over-predicts shear strains measured in the non-symmetrical staged tests.