The bearing capacity of pile foundation in soft clay under cyclic loading

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 pile side load transfer models for soft clay under cyclic loading are based on the hyperbolic model, which is more complex and less efficient. In this paper, a soil mechanics model of considering the cyclic weakening effect of soft clay is presented. The secondary development of the ABAQUS subroutine is utilized to describe the cyclic weakening characteristics of soil and the method is introduced into the calculation of the pile-soil interaction model. The conventional static pile side load transfer model is enhanced, and a trilinear model of pile side resistance force that can account for the cyclic weakening effect of soft clay is proposed. A calculation method for pile foundation bearing capacity is established based on the load transfer method with the cyclic weakening effect of soil. The results of the calculations are compared with the results of the model tests, and the correctness the pile bearing capacity calculation method considering the cyclic weakening effect of soft clay is verified. Finally, the method is applied to the calculation of ultimate bearing capacity of pile foundation in the actual engineering of offshore wind power pile foundation. It is found that when the monopile foundation in soft clay foundation is subjected to cyclic loading, the monopile ultimate bearing capacity will show a tendency of first fast and then slow attenuation with the increase of the number of cycles. And with the increase of cyclic load level, the decay rate of the ultimate bearing capacity of monopile increases, and the increase rate is from slow to fast. When the cyclic load level exceeds a certain limit value, the decay rate of ultimate bearing capacity increases rapidly.