Centrifugal shaking table tests on dynamic response of bucket foundation-sandy soil

In the sites with seismic intensity greater than 7 degrees, liquefaction identification of sandy soil within 15 m is required by the relevant seismic codes. The shallow-buried bucket foundation, a new type of foundations for offshore wind turbines, is sensitive to the liquefaction of shallow sandy soil subjected to earthquake loads because of the shallow depth of its burial. To study the seismic response rules of shallow buried-bucket foundation-sandy soil, a series of centrifugal shaking table tests are designed and carried out. Acceleration changes of shallow-buried bucket foundation and sandy soil as well as the pore pressure responses of the sandy soil are monitored during and after earthquakes. Also, the influence rules of bucket foundation on the anti-liquefaction performance of sandy soil foundations are analyzed. The results show that the acceleration response factor of bucket foundation in sandy soil subjected to seismic loading is greater than 1.0, and the response coefficient is positively correlated with the bucket foundation weight. As the shallow-buried bucket foundations are usually larger than 30 m in diameter and 2000 t in weight, the combined effect with the upper loads significantly increases the additional stress in the sandy soil foundation, which is beneficial to improve the anti-liquefaction capability of sandy soil foundations. Based on the excess pore pressure ratio, the method for determining the anti-liquefaction performance of sandy soil affected by the bucket foundation is established. And the degree of improving the anti-liquefaction of sandy soil by the bucket foundation is quantitatively analyzed. © 2020, Editorial Office of Chinese Journal of Geotechnical Engineering. All right reserved.