Sand–clay mixtures are widely distributed in offshore seabeds and may experience long-term cyclic loading from waves and marine structures. This study investigates the effects of clay content on the drained cyclic response of sand–clay mixtures. Drained cyclic simple shear tests were conducted on saturated sand–clay specimens with different clay contents for 10000 cycles. The results show that the cyclic shear modulus generally increased with cycle number. Specimens with relatively low clay contents exhibited a rapid increase during the early cycles, followed by a continued increase at a lower rate, whereas clay-rich specimens showed an initial reduction followed by an overall increase with more pronounced fluctuations. At the same cycle number, the cyclic shear modulus decreased with increasing clay content. The hysteresis-loop area generally increased with cycle number but decreased as clay content increased, indicating reduced energy dissipation in clay-rich mixtures.These findings provide useful experimental evidence for evaluating the long-term mechanical response of offshore foundations under cyclic loading.

Sand–clay mixture; Clay content; Dynamic cyclic simple shear test