摘 要

自推动东西部协调发展以来，我国对西部基础建设的投资逐渐增加，从而对西部地区深水桥梁建造的需求及要求都更上了一个层次。而这些桥梁大多建设在地震高发区，墩与水的耦合作用通过改变结构的动力特性来影响桥墩结构对地震的响应，故为降低地震对深水桥梁的不良影响，在对深水桥梁进行抗震设计时，考虑动水压力是必不可少的。但现阶段我国对地震作用下深水桥梁的动力响应分析研究尚存不足与局限，影响了深水桥梁的抗震设计与建设。因此，深入研究深水桥墩所处的流固耦合环境，寻求高效的分析方法具有重要的工程实际意义。本文将基于国内外在该领域现有的研究基础及其研究动向，以深水空心圆形桥墩为研究对象，通过其地震水动力模型及数值模拟方法研究来总结流固耦合效应对动力特性与动力响应的影响规律，主要内容如下：

1、对国内外有关流固耦合方面的研究现状进行了详细介绍，对现有该领域的分析方法进行了阐述，在这个基础上概括目前这方面研究所存在的不足之处，同时介绍本此的研究方法及其研究路线。

2、基于势的流固耦合理论，利用ADINA软件对考虑内水影响的深水圆形空心桥墩进行了三维有限元模型的建立并对建立过程及其注意事项做了具体阐述，并对重点内容如边界条件的定义、网格的划分等做了重点分析。

3、基于所建的三维有限元流固耦合计算模型对考虑内水影响的深水空心圆形桥墩进行了动力特性的分析，概括总结了流固耦合效应对深水圆形空心桥墩动力响应的影响；研究发现，考虑流固耦合作用之后，深水空心圆形桥墩的自振频率相比未考虑时有所减小；在流固耦合的作用下，深水空心圆形桥墩第一阶振型所对应的自振频率随着水位的升高而减小。而当水位高度不及桥墩高度的二分之一时，流固耦合效应对深水空心圆形桥墩自振频率的影响则可忽略不计。

4、利用ADINA软件建立不同水位条件下空心圆形桥墩的水下等效模型，通过改变不同水位情况下墩体浸水部分的等效密度来模拟内外流体对空心圆形桥墩的作用。研究发现等效模型的各项参数与原模型的各项参数吻合较好，误差保持在非常微小的范围内，并且等效模型的前两阶振型的频率都略微大于原模型前两阶振型的频率。

5、通过在原有模型的基础上改变墩底材料弹性模量以及整个结构材料的弹性模量来模拟桥墩结构墩底局部损伤退化及整个墩体一致损伤退化的情况。研究表明，结构的损伤退化与水位的增加都会增大动水附加质量，且一致损伤退化对其影响大于局部损伤退化。

关键词：深水空心桥墩，数值模拟，流固耦合，动力效应

Abstract

Since the coordinated development of the eastern and western regions, China's investment in infrastructure construction in the west has gradually increased, thus the demand and requirements for the construction of deep-water bridges in the western region have reached a certain level. In order to reduce the adverse effect of the earthquake on the deep water bridge, when the deep-water bridge seismic design is carried out, the coupling effect of the pier structure on the earthquake is affected by changing the dynamic characteristics of the structure. Must consider the role of hydrodynamic pressure. However, the research on the dynamic response of the deep-water pier under the earthquake is not enough and limited, which affects the seismic design and construction of the deep-water bridge. Therefore, it is of great practical significance to study the fluid-solid coupling environment of deep water piers and find an efficient analytical method. Based on the existing research base and its research trends in related fields at home and abroad, this paper takes the deepwater hollow circular piers as the research object, and analyzes the dynamic characteristics and dynamic of the fluid-solid coupling effect by its seismic hydrodynamic model and numerical simulation method Response to the impact of the law, the main contents are as follows:

1、In this paper, the current research on fluid-solid coupling is introduced in detail, and the existing fluid-solid coupling analysis methods are analyzed. On this basis, the shortcomings of the current research are summarized. On the basis of this, the author summarizes the shortcomings of the current research and puts forward the research methods and research routes of this paper.

2、Based on the theory of fluid-solid coupling, the three-dimensional finite element model of deep-water circular hollow piers considering the influence of internal water is established by using ADINA software. The establishment process and its precautions are described in detail, and the key content such as the definition of boundary conditions, the division of the grid to do a key analysis.

3、Based on the three - dimensional finite element fluid - solid coupling model, the dynamic characteristics of deep - water hollow circular piers considering the influence of internal water are analyzed. The influence of fluid - solid coupling on the dynamic characteristics of deep - water circular hollow piers is summarized. It is found that considering the fluid - solid coupling will reduce the natural frequency of deep - water hollow circular piers. Under the action of fluid - solid coupling, the natural frequency corresponding to the first - order mode of the deep - water hollow circular piers decreases with the depth of the surrounding water body. The effect of fluid - solid coupling on the natural frequency of deep - water hollow circular piers is negligible.

4、Based on ADINA，the underwater equivalent model of hollow circular piers under different water depth conditions was established. The influence of internal and external water bodies on the hollow circular piers was simulated by changing the equivalent density of the immersion part of the piers under different water depth.The results show that the parameters of the equivalent model are in good agreement with the original model, and the error is kept within a very small range. The first two modes of the equivalent model are slightly larger than the first two modes of the original model.

5、The elastic deformation modulus of the pier bottom material and the elastic modulus of the whole structure material are changed on the basis of the original model to simulate the damage of the pier structure and the damage of the whole pier after the earthquake. The results show that the damage of structure damage and the increase of water depth increase the additional water quality, and the damage of uniform damage is greater than that of local damage.

Key words: deep-water hollow pier; fluid-structure interaction; numerical simulation；dynamic properties; seismic response；site condition.

目录

第1章 绪论 1

1.1研究背景 1

1.2研究现状 2

1.3研究目的 4

1.4研究内容 5

1.5技术路线图 5

第2章 考虑内水影响的深水空心圆形桥墩三维流固耦合模型的建立 7

2.1 概述 7

2.2 三维有限元数值模型的建立 7

2.2.1 模型概述及材料参数设置 7

2.2.2 建立三维流固耦合模型 7

第3章 考虑内水影响的深水空心圆形桥墩结构模态参数特征 10

3.1 概述 10

3.2 40m空心圆形桥墩结构模态参与特征 10

3.2.1第一、二阶自振频率及频率变化率 10