Long term cyclic behavior and strength of marine silty sand investigated by cyclic direct simple shear apparatus

As a renewable clean source of energy, offshore wind power is capable of supplying increasingly demand for energy. Offshore structures are normally subjected to various cyclic loads from wind, waves, and tidal loads. Depending on the cyclic degradation, the foundation load capacity under cyclic loading conditions may be different than the monotonic loading conditions. Hence, special attention should be given to evaluate the effect of cyclic load on the behavior of soil and structure. In this study, utilizing Cyclic Direct Simple Shear apparatus (CDSS), the long-term cyclic behavior of marine silty sand is investigated. Failure contours are proposed using the test results. The failure contours are useful tool to predict the shear behavior of the ground when subjected to the dynamic loading. The failure contours are generated considering various parameters including confining pressure and soil relative density. Finally, the effect of vertical loading on the failure contours are investigated.