摘 要

由于近海单腿平台的工作环境是在近海海面上，平台会受到各种工作载荷和风浪流等自然环境载荷的作用，因此对平台结构安全性的分析是确保平台在服役年限内正常使用的重要环节。近海单腿平台的桩腿是平台的重要组成部分，承受平台的竖向载荷和海风、海流和波浪的横向荷载。单腿平台的桩腿通常采用打入的方式插入海底土泥线以下的某一深度处，因此考虑桩土相互作用的影响是分析桩腿强度乃至整个平台强度所必须要考虑的问题。

本文采用通用有限元软件ANSYS研究了考虑桩土相互作用的简易单腿平台的静力响应、固有振动和瞬态动力响应。首先建立了考虑桩土相互作用的单腿平台的有限元模型，其中桩土相互作用采用基于P-y曲线法的地基反力法来考虑。然后确定了单腿平台受到的波流耦合力极值和相应的相位角。接下来施加单腿平台受到的静力载荷，包括风载荷、平台顶部载荷、自重、波流耦合载荷，和边界条件，研究了单腿平台的静力响应。最后研究了单腿平台的固有振动以及动态波流载荷作用下的瞬态动力响应。

关键词：单腿平台；ANSYS；桩土互相作用；P-y曲线；静力分析；波流耦合力极值分析；模态分析；瞬态动力分析

Abstract

Because the working environment of the offshore single-leg platform is on the sea surface, the platform will be affected by various working loads and natural environmental loads such as wind and wave current. Therefore, the analysis of the platform structure safety is important to ensure the normal use of the platform within the service life. The legs of the offshore single-leg platform are an important part of the platform and are subject to the vertical load of the platform and the lateral loads of sea winds, currents and waves. The leg of a single leg platform is usually inserted into a certain depth below the mudline of the seabed by means of driving. Therefore, considering the effect of the pile-soil interaction is a problem that must be considered when analyzing the strength of the leg and even the strength of the entire platform.

In this paper, the general finite element software ANSYS is used to study the static response, natural vibration and transient dynamic response of a simple one-leg platform considering the pile-soil interaction. Firstly, the finite element model of the single-leg platform considering the pile-soil interaction is established. The pile-soil interaction is considered by the ground-based reaction method based on the P-y curve method. Then the wave-flow coupling force extremes and corresponding phase angles of the single leg platform were determined. Next, the static loads imposed on the single-leg platform, including the wind load, the top load of the platform, its own weight, the wave-flow coupling load, and the boundary conditions, were applied to investigate the static response of the single leg platform. Finally, the natural vibration of a single-leg platform and transient dynamic response under dynamic wave loading are studied.

Key words: Single-leg platform；ANSYS；Pile-soil interaction；P-y curve；Static analysis；Wave-flow coupling force extreme value analysis；Modal analysis；Transient dynamic analysis

目 录

第1章 绪论..................................................................................................................7

• 1. 目的及意义……………………………………………………………………..7
  2. 国内外研究现状………………………………………………………………..7
  3. 本文研究内容…………………………………………………………………..8

第2章 ANSYS软件………………………………………………………………….9

2.1 概述…………………………………………………………………………….9

2.2典型单元简介…………………………………………………........................10

2.2.1 PIPE16单元………………………………………………………………10

2.2.2 PIPE59单元……………………………………………………………....11

2.2.3 COMBIN39单元…………………………………………………………12

第3章 简易单腿平台有限元模型的建立………………………………………….13

3.1考虑桩土互相作用的地基反力法…………………………………………....13

3.2 P-y曲线及其ANSYS实现……………………………………………………13

3.3 问题描述………………………………………………………………...........14

3.4 工作环境设置………………………………………………………………...15

3.5单元类型定义………………………………………………………………....16

3.6 单元实常数设置……………………………………………………………...16

3.7 材料参数和环境荷载参数设置……………………………………………...20

3.8 几何模型建立………………………………………………………………...20

3.8.1 节点建立…………………………………………………………………20

3.8.2 单元建立…………………………………………………………………21

第4章 简易单腿平台的静力分析…………………………………………………23

4.1 求解类型设置………………………………………………………………...23

4.2 位移边界条件设置…………………………………………………………...23

4.3 施加载荷……………………………………………………………………...23

4.3.1 风荷载定义………………………………………………………………23

4.3.2 平台顶部载荷定义………………………………………………………24

4.3.3 重力场定义………………………………………………………………24

4.4 求解…………………………………………………………………………...25

4.5 单腿平台的静力分析结果……………………………………………….......25

4.5.1 结果文件读入……………………………………………………………25

4.5.2 整体变形图绘制…………………………………………………………25

4.5.3 节点位移云图绘制………………………………………………………26

4.5.4 单元应力及应变云图绘制………………………………………………27

4.5.5 单元节点弯矩云图绘制…………………………………………………28

4.5.6 单元节点弯矩和应力列表显示…………………………………………28

4.6 波浪相位角的搜索…………………………………………………………...30

4.6.1 单腿平台的有限元模型…………………………………………………30

4.6.2 前处理……………………………………………………………………31

4.6.3 搜索相位角………………………………………………………………31

第5章 简易单腿平台的模态分析和瞬态动力分析………………………………32

5.1 模型修改……………………………………………………………………...32

5.2 位移约束设置………………………………………………………………...32

5.3 各种选项的设定及模态求解………………………………………………...32

5.4 单腿平台的模态分析结果…………………………………………………...32

5.4.1 固有频率…………………………………………………………………33

5.4.2 模态振型…………………………………………………………………33

5.5 波流载荷作用下单腿平台的瞬态动力分析………………………………...35

5.5.1 环境参数修改……………………………………………………………36

5.5.2 求解选项设置……………………………………………………………36

5.5.3 典型节点位移-时间曲线绘制…………………………………………...36

5.8.4 典型单元应力-时间曲线绘制…………………………………………...37

第6章 结论………………………………………………………………………….38

参考文献……………………………………………………………………………..39

致谢…………………………………………………………………………………..40