毕业论文移动版

摘要：石油和天然气资源在人类社会中扮演着重要角色。近年来随着陆上油气资源的大 规模开发，已面临枯竭，人们不得不将目光转向海上油气资源的开发。在海上油气资 源的开发过程中，自升式平台作为海洋油气资源开发的一种重要形式，其结构安全和 制造成本显得格外重要。本文主要研究自升式平台桁架式桩腿结构强度的敏感性，介 绍了桩腿所处的环境中载荷的理论计算方法，运用有限元软件对桩腿进行建模。从外 水平撑杆壁厚、外水平撑杆长度和水下部分节距出发，通过改变桩腿结构的几何参数， 分析桩腿的应力分布情况。研究表明，桩腿的最大应力处一般出现在与主船体接触的 部分。最大应力随着外撑杆壁厚和长度变化存在突变情况，其水下节距对最大应力影 响不大。在设计过程中，可以分析结构敏感性选取合适的外水平撑杆长度和壁厚，适 当增大桩腿水下部分的节距，在满足结构强度要求的前提下大大节约了成本。

关键词：自升式平台；桩腿；环境载荷；结构强度；

Abstract：Oil and natural gas resources play an important role in human society. In recent years, with the large-scale development of onshore oil and gas resources, they have been exhausted.People have to turn their attention to the development of offshore oil and gas resources. Jack-up platform is an important form in the development of marine oil and gas resources, and its structural safety and manufacturing cost are very important. In this paper, the sensitivity of the structural strength of the truss-type piles is studied, and the theoretical calculation method of the load in the environment of the pile is introduced. The finite element software is used to model the pile legs. The stress distribution of the leg is analyzed by changing the geometrical parameters of the structure include the length and thickness of the external horizontal strut and the distance of the underwater part. Studies have shown that the maximum stress at the leg is generally present in contact with the main hull. The maximum stress varies with the wall thickness and length of the external horizontal strut while its underwater pitch has little effect on the maximum stress. In the design process，the structural sensitivity can be analyzed in order to get the proper length and wall thickness of external horizontal strut. The distance of the underwater part of the pile can be also increased to save the cost under the premise of the structural strength requirements.

Keywords: jack-up platform；leg；environmental load；structural strength

目    录 

第一章    绪  论 . 1 

1.1 课题研究的背景和意义 . 1 

1.2 国内外研究现状 . 4 

1.3 本课题的主要研究内容和方法 . 6 

第二章    平台桩腿静力计算及环境载荷  8 

2.1 概述 . 8 

2.2 风载荷 . 8 

2.3 波浪载荷  10 

2.4 流载荷  15 

2.5 动力放大系数（DAF） . 16 

2.5.1 时域分析法  17 

2.5.2 频域分析法  18 

2.5.3 SDOF 法 . 18 

2.6 P- 效应 . 19 

2.7 结构强度  19 

2.7.1 屈服强度  19 

2.7.2 屈曲强度  21 

2.7.3 疲劳强度  21 

2.8 本章小结  21 

第三章    有限元计算  22 

3.1 软件概述  22 

3.2 桩腿的等效直径  22 

3.2  模型基本参数介绍 . 23 

3.2.1 模型初始属性  23 

3.2.2 作业工况  24 

3.2.3 桩腿有限元模型  24