桩基础结构的变异性设计及其性能优化的研究

发布时间：2018-08-22 09:50

【摘要】：海上风机主要由三部分组成,即桩腿部分、桩基础部分以及风机部分。桩基础的成本占总成本的23%,海上风电的高成本投入制约着海上风电的发展。海上桩基础风机的工作工况比较恶劣,除了需要承受风、浪、流载荷还要受到地震载荷等的作用,同时需要进行特殊的防腐蚀处理等。在满足桩基础刚度、强度及屈曲压力的前提下,若能降低桩基础的重量即可达到降低总成本的作用。首先,本文应用挪威船级社的标准,对三桩基础进行概念建模,得到等直径撑杆三桩基础总装模型。在等直径标准模型的基础上,应用变异性原理中的结构及截面变异原理,对桩基础的结构和撑杆的截面形式进行变异性设计。其次,基于流固耦合计算方法,应用的质量守恒方程、动量守恒方程、能量守恒方程,对风、浪、流条件下的三桩基础总装模型系统进行外载荷数学建模,得到了三桩基础总装模型的力学特性。并应用流体力学(CFD)中的CFX软件数值模拟了总装模型的流固耦合特性,对桩基础的速度及压力场进行性能分析。再次,应用数学方法计算桩基础承受的风、浪、流外载荷,对截面变异模型应用计算力加载,通过对比结构及截面变异模型的结果,得到同等工况条件下应力和总位移最小的模型,为多目标优化做好准备。最后,本文采用多目标遗传算法中的DOE试验设计方法对基础中心柱的直径和厚度、桩腿的直径和厚度、撑杆的直径和厚度、桩腿和中心柱的距离等13个几何设计参数进行多样点设计。以总重量、总体位移和等效应力为目标函数,对等直径撑杆基础的总装模型、结构及截面变异模型中承载能力强的进行优化设计。以采集的样点响应作为样本点响应面分析法(RSM)构建设计空间,在整个设计空间中寻找满足目标函数的Pareto最优解集。本文数值模拟了桩基础在复杂海况条件下的应力分析,并且对桩基础风机总装模型进行了多目标遗传优化,在满足强度、刚度及临界压力载荷的条件下寻求重量的最小值,对海上风电事业的发展起到促进作用。
[Abstract]:Offshore fan is mainly composed of three parts, namely, pile leg, pile foundation and fan. The cost of pile foundation accounts for 23% of the total cost, and the high cost input of offshore wind power restricts the development of offshore wind power. The working condition of offshore pile foundation fan is very bad. Besides wind, wave, current load and so on, it is necessary to carry out special anticorrosion treatment and so on. On the premise of satisfying the stiffness, strength and buckling pressure of pile foundation, if the weight of pile foundation can be reduced, the total cost can be reduced. Firstly, this paper uses the Norse Classification Society standard to model the three pile foundation concept, and obtains the model of equal diameter supporting pole three pile foundation assembly. Based on the standard model of equal diameter, the structure of pile foundation and the cross-section form of bracing are designed by applying the variation principle of structure and section in the principle of variability. Secondly, based on the fluid-solid coupling calculation method, the applied mass conservation equation, momentum conservation equation, energy conservation equation, and the external load mathematical modeling of the three-pile foundation assembly model system under the conditions of wind, wave and current are established. The mechanical properties of three pile foundation assembly models are obtained. The fluid-solid coupling characteristics of the assembly model are numerically simulated by using the CFX software of fluid dynamics (CFD), and the performance analysis of the velocity and pressure field of pile foundation is carried out. Thirdly, the external loads of wind, wave and current on pile foundation are calculated by using mathematical method, and the calculation force is applied to the cross-section variation model, and the results of structure and cross-section variation model are compared. The model of minimum stress and total displacement under the same working condition is obtained to prepare for multi-objective optimization. Finally, the diameter and thickness of the center column, the diameter and thickness of the pile leg, the diameter and thickness of the bracing rod, and the diameter and thickness of the supporting rod are calculated by using the DOE test design method in the multi-objective genetic algorithm. 13 geometric design parameters, such as the distance between the pile leg and the center column, are designed for various points. Taking total weight, total displacement and equivalent stress as objective functions, the optimal design of the assembly model of equal-diameter brace foundation and the structural and cross-section variation model with strong bearing capacity is carried out. The sample response is used as the sample point response surface analysis (RSM) to construct the design space, and the Pareto optimal solution set satisfying the objective function is found in the whole design space. In this paper, the stress analysis of pile foundation under complex sea conditions is numerically simulated, and the multi-objective genetic optimization of the pile foundation fan assembly model is carried out. The minimum weight is obtained under the condition of satisfying the strength, stiffness and critical pressure load. It will promote the development of offshore wind power industry.
【学位授予单位】：哈尔滨工程大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM614

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