Seismic Response of Shallow Bucket Foundation of Soft Clay

Soft clay is the main component of offshore ground in China. In areas prone to frequent earthquakes, the action of seismic loading will lead to the weakening of the soil strength of the shallow bucket foundation of soft clay. The shallow bucket foundation is a new type of foundation for offshore wind turbines. This type of foundation has a shallow buried depth. Thus, the weakening of the soil strength of the shallow bucket foundation of soft clay due to seismic loading has a considerable influence on the stability of the bucket foundation. To investigate the seismic response of the shallow bucket foundation of soft clay, a series of dynamic centrifuge tests, which were designed on the basis of the first-order natural frequency of the shallow bucket foundation, were performed. In the tests, the pore water pressure response of soil during the entire loading period, the acceleration of the shallow bucket foundation of clay ground, and the shear strain and shear stress were measured to determine the seismic response regularity. The results show that seismic loading has a hysteresis effect on the accumulation of pore water pressure. The accumulation of pore water pressure along the centerline of the bucket is smaller than that around the bucket. The additional load on a large area with shallow bucket foundation reduces the degree of weakening of the soil strength of clay due to seismic loading. Under the action of the EL Centro wave, the acceleration of the shallow bucket foundation of clay ground decreases linearly with the decrease in buried depth. Under the action of the SIN wave, the acceleration of the shallow bucket foundation of clay ground decreases nonlinearly with the decrease in buried depth. The acceleration response of the bucket lid is equal to that of the tower drum. Meanwhile, the maximum acceleration of the bucket lid and tower drum is smaller than that of the clay ground. The shear stress-strain response of the clay ground under the bucket increases with the increase in buried depth. The shear strain at the plate of the bucket base also increases. © 2020, Editorial Board of Journal of Tianjin University(Science and Technology). All right reserved.