摘 要

当今世界处于一个高速发展的时期，对能源的需求非常迫切。风能作为一种高效、清洁的能源，是支持未来社会发展的一种重要能源形式。随着人类越来越关注环境保护，对清洁能源的需求在很大的程度上推动海上风电技术的发展。海上风机基础是海上风机结构必不可缺的一部分，其设计需要考虑环境载荷、桩土相互作用等多方面影响。单桩基础是常见的一种浅海固定式风机的基础形式，具有结构形式简单的特点。因此，本文对海上风机单桩基础进行基本尺寸的设计，然后在这个基础上对其所受到的荷载进行分析和对其稳定性进行校验。

首先，本文介绍了风能在当今世界中的重要战略意义以及作为支撑风力发电机的基础形式的种类和其优缺点。通过参考文献，借助规范资料，并结合所选取的研究对象的海洋地质条件，选取了NREL-5MW风机作为所设计基础的风机，来进行单桩基础概念上的设计。

其次在这基础上，对海上风机单桩基础工作时受到的环境荷载进行分析，主要为水平风载荷、波浪载荷、以及流载荷。通过借助规范公式计算风机载荷，在计算波浪载荷和流载荷的时候采用Morrison公式并借助三维水动力软件进行建模分析。通过对比两者的结果来分析环境荷载的作用。其次本次设计将桩基设计的直径作为改变量，来观察其所受到的荷载的变化。

最后本文归纳了之前用来分析桩基承载力的方法，选取了P-y曲线法和m法作为分析和计算曲线的方法，并将之前算出来的荷载来和其比较，看是否符合要求。

关键词：海上风机；单桩基础；p-y曲线法；环境荷载；稳定性分析

Abstract

The world is now under a rapid development phase, resulting in an urgent energy demand. As an efficient and clean energy, the wind energy is one important energy source which can well support the future development of the society. As human beings pay more and more attention to the protection of environment, the large demand for clean energy has greatly pushed the development of offshore wind energy technology. Foundation is an essential element of the offshore wind turbine, and its design needs to consider various aspects including the environmental loads and the foundation-soil interaction. Monopile foundation is one typical type of foundation for shallow water fixed wind turbines, which has the feature of simple structure form. Hence, this paper conducts the design of the basic dimensions of monopole foundation of an offshore wind turbine, calculates the environmental loads acting on the foundation and then performs stability check of the monopole foundation based on the calculated environmental loads.

First of all, this paper introduces the important strategic significance of wind energy in today's world and its advantages and disadvantages as a basic form to support wind turbines. Based on the references, the NREL-5MW wind turbine is selected as the basis to design the monopole foundation. In addition, the conceptual design of the monopile foundation is carried out based on the relevant standards and marine geologic conditions. Secondly, on the basis of the foundation design, the environmental loads on the monopile foundation of the offshore wind turbine are analyzed, which include the wind load, wave load and current load in the horizontal direction. By calculating the wind load from the empirical formula, the Morison formula is used to calculate the wave load and the current load and the modeling of wave loads is carried out by using the 3D hydrodynamic software as well. The effect of environmental loads is analyzed by comparing the results from Morison formula and software. In addition, the effect of pile diameter on the wave loads is analyzed. Finally, this paper summarizes the methods used to analyze the horizontal bearing capacity of monopile foundation. The P-y curve method and the m method are chosen as the method of analyzing and calculating the curve. These results are compared with the loads calculated in the previous stage to check whether design satisfies the requirement.

Key words：Offshore wind turbine; Pile foundation; P-y curve method; Environmental load；Stability analysis