Abstract: To study the lateral cyclic loading response of large-diameter monopiles in soft clay, the centrifugal model tests of large-diameter monopiles in soft clay under different cyclic loading forms (one-way and two-way) were carried out. The deformation characteristics of large-diameter monopiles, stiffness weakening, bending moment, cyclic p-y curves and excess pore-water pressure were relatively analyzed. The test results show that the load-displacement curves show obvious nonlinear retardation energy consumption and displacement accumulation properties. Compared with the one-way cycle loading, the two-way cycle loading causes a significant cumulative displacement, which is influenced by both the number of cycles and the loading amplitude. The cumulative displacement consists of recoverable elastic deformation and unrecoverable plastic deformation, which is related to the number of cycles and loading stress level. The two-way cycle loading causes the weakening of pile-top stiffness, thereby enhancing the bending effect of the pile. The accumulation of excess pore-water pressure is related to the cycle number and loading amplitude, with a more pronounced effect observed under two-way loading conditions.

Key words: offshore wind turbines, pile foundation, cyclic loading, soft clay, centrifuge test