Research On Dynamic Response Of Group Pile Bucket Foundation Of New Offshore Wind Power

With the progress and development of contemporary offshore wind power technology,the installation of high-power offshore wind turbines and the development of wind energy in deep sea areas have become the inevitable trend of the development of offshore wind power industry,which also puts forward higher requirements for the bearing capacity of offshore wind power foundation.Facing the complex marine environment and increasing capacity of offshore wind power unit,the existing offshore wind power foundation types have been unable to meet the requirements of its bearing capacity.In order to improve the bearing capacity of offshore wind power foundation,a new type of pile group bucket foundation composed of bucket foundation and steel pipe pile is proposed,and its unique structure type brings higher bearing capacity to the foundation.This paper takes the group pile bucket foundation as the research object and conducts the following research:(1)This paper summarizes the theoretical methods for calculating the horizontal bearing capacity of pile foundation and bucket foundation,and deduces the formula for calculating the horizontal bearing capacity of group pile bucket foundation according to the limit equilibrium method and assuming the distribution form of foundation soil resistance.(2)With ABAQUS software,three-dimensional finite element models of four foundation types are established,including single-bucket(B0P)foundation,single-bucket plus one pile(B1P)foundation,single-bucket plus three piles(B3P)foundation and single-bucket plus four piles(B4P)foundation.The horizontal bearing characteristics of group pile bucket foundation with different pile number,pile diameter and pile distribution are analyzed under the condition of a certain amount of steel.The reliability of the theory is verified by comparing the finite element results with the theoretical values,and the group pile bucket foundation has higher bearing capacity.(3)By applying time-varying wave loads,the stress changes of group pile bucket foundation and the displacement changes of foundation and mud surface are studied.By analyzing the stress nephogram,it is found that the stress concentration areas in the foundation appear in the connection areas between top cover and transition section,top cover and steel pipe piles.According to the magnitude of peak displacement,it is concluded that group pile bucket foundation has smaller peak displacement under wave load,that is,group pile bucket foundation has better ability to resist wave load than bucket foundation.(4)By loading different types of earthquake waves with different strengths,the dynamic response of group pile bucket foundation under earthquake load is studied.It is found that the peak acceleration and displacement of group pile bucket foundation are smaller than those of single-bucket foundation under the same type of seismic waves,which means that the stability and seismic performance of group pile bucket foundation are better than those of bucket foundation.