Variability Design And Performance Optimization Of The Pile Foundation Structure

Offshore wind turbine mainly consists of three parts including pile leg, pile foundation and wind turbine. The cost of pile foundation accounts for23% of the total cost and the high cost of pile foundation wind turbine restricts the development of offshore wind turbine. Besides earthquake load, the work condition of offshore pile foundation including wind, wave, stream loads is worse, and special corrosion resistance is required to the offshore pile foundation at the same time. Under the premise of meeting the stiffness, strength and yield pressure of offshore pile foundation, if the weight of the pile foundation can be lightened, the effect of declining the total cost of offshore pile foundation also would be obtained.First of all, this paper use DNV standard to establish a onceptual model of three pile foundation and get a equal diameter three pile foundation assembly model. On the basis of equal diameter standard model, using structural and section variability principle to design the pile foundation structure and section of the supporting rod.Secondly, the paper proceeded external load mathematical modeling to the assembly model system of three piles foundation under the conditions including wind, wave, stream loads using mass conservation equation, momentum conservation equation, energy conservation equation based on Fluid-structure coupling calculation methods. In addition to, simulating the fluid-solid coupling characteristics of assembly model with Numerical, the paper carried out a performance analysis to the velocity and pressure field of offshore pile foundation by the CFX in Fluid mechanics (CFD).Again, using mathematical methods for the calculation of wind, wave, current bearing load of pile foundation which is used to calculate the force loading on the application of section variation model by comparing the structure and cross section variation model results, given the same conditions of stress and displacement of the minimal model get ready for the multi-objective optimization.Finally, this paper using DOE test design method of multi objective genetic algorithm to various design which is on the basis of center column diameter and thickness, diameter and thickness of foundation leg, diameter and thickness of rod, distance foundation leg and the center column 13 geometric design parameters.Using overall displacement and equivalent to the total weight and stress as the objective function to optimize the equal diameter pile foundation assembly model, structure and cross section variation model which has the strong carrying capacity.Apply response surface methodology (RSM) to build the design space with samples as response points and then apply multi-objective genetic algorithm to search a set of Pareto optimal solutions and to meet the objective function in the entire design space.This paper numerically simulate the stress of pile foundation under complex stress analysis of sea conditions, and multi-objective genetic optimize the offshore wind turbine assembly pile foundation model, seeking to meet the minimum weight, stiffness and buckling pressure load conditions, the development of offshore wind plays a promoting role.