Abstract:
It is known that the strength and stiffness of soft clay will decrease with the continuous action of cyclic loading. Currently, the majority of studies on load transfer models for piles in soft clay under cyclic loading are based on the hyperbolic model, which are more complex and less efficient. In this study, a mechanical model for soils considering the cyclic weakening effects of soft clay is proposed. The secondary development of the ABAQUS subroutine is utilized to describe the cyclic weakening characteristics of soils, and the method is introduced into the calculation of the pile-soil interaction model. The conventional static load transfer model for piles is enhanced, and a trilinear model for resistance force of piles that can account for the cyclic weakening effects of soft clay is proposed. A method for calculating the bearing capacity of pile foundation is established based on the load transfer method with the cyclic weakening effects of soils. The calculated results are compared with those of the model tests, and the correctness of the proposed method considering the cyclic weakening effects of soft clay is verified. Finally, the method is applied to the calculation of the ultimate bearing capacity of pile foundation in an actual project of offshore wind power pile foundation. It is found that when the monopile foundation in soft clay is subjected to cyclic loading, the ultimate bearing capacity of the monopile will show a tendency of first fast and then slow attenuation with the increase of the number of cycles. With the increase of the cyclic loading level, the decay rate of the ultimate bearing capacity of the monopile increases, and the increase rate is from slow to fast. When the cyclic loading level exceeds a certain limit value, the decay rate of the ultimate bearing capacity increases rapidly.