近海桥梁上部结构波浪作用研究

发布时间：2018-01-08 09:24

本文关键词：近海桥梁上部结构波浪作用研究　出处：《哈尔滨工业大学》2017年博士论文　论文类型：学位论文

【摘要】：近海桥梁是沿海快速交通网的重要组成环节,既有近海低矮桥梁由于净空不足在台风(飓风)引起的巨型波浪作用下可能发生严重破坏,影响灾后救援及重建工作并造成严重的经济和社会损失。揭示桥梁结构的波浪作用机理,确定近海桥梁结构所受波浪作用的影响因素,建立合理的波浪力估算方法对近海桥梁结构安全有着重要意义。本论文针对无通航要求的近海低矮桥梁上部结构所受波浪力展开研究,主要内容、方法及结果如下:(1)开展了1:10缩尺比的桥梁模型波浪水动力试验。试验所用模型包含了一个完整的主梁桥跨、两个1/4长度的临跨和两座桥墩。试验测试了不同波浪要素的正向入射波浪和斜向入射波浪作用下,不同净空上部结构的波浪力和结构底面压强。试验结果表明:竖向波浪力包含了两个幅值相当高频砰击力和低频准静力成分,而水平作用力中高频砰击力幅值很小。当波浪斜向入射时,净空较小或为负值时,0°波向角入射波浪在桥梁上部结构上产生的波浪力最大;当净空较大时,竖向波浪力在15°波向角达到最大。此外,波浪力在空间分布上存在差异,通常迎浪侧支座承担更大的波浪力。(2)基于势流理论建立了正向入射波浪作用下全淹没桥梁上部结构的二维波浪力理论模型。首先通过分离变量法求解满足边界条件的控制方程,然后利用特征展开匹配法确定整个波浪-结构作用场的速度势函数。将势流理论计算结果与试验结果进行对比,验证了理论模型的正确性。将理论计算结果与AASHTO规范方法进行对比,发现该规范存在高估竖向波浪力和低估水平波浪力的现象,并基于理论模型计算结果提出了AASHTO规范中六种桥梁上部结构的波浪力估算简便方法。(3)基于势流理论建立了斜向波浪作用下全淹没桥梁上部结构受的三维波浪力理论模型。假设速度势函数在时域内和桥跨长度方向具有周期性,将控制方程由三维Laplace方程降维为Helmholtz方程。首先给出了满足边界条件的带有未知系数控制方程的解,然后利用相邻子域交界面处的速度势和水平速度连续性求解了速度势函数中的待定系数,得到整个流域的速度势函数。利用线性Bernoulli方程从速度场得到压强场,并沿物面积分得到了斜向波浪作用下淹没桥梁上部结构的波浪力。利用所建立模型研究了波向角和上部结构构件几何特征对波浪力的影响,发现波向角为零度时淹没桥梁上部结构时所受到的波浪力最大。(4)开展了畸形波对水平方箱的波浪砰击试验,建立了淹没方箱波浪力的势流理论模型。首先提出了利用多初相位相速度法在水槽中产生连续聚焦波的试验方法,并通过实测和理论波面时程和频谱的对比分析了该方法的有效性。试验研究了水平方箱模型在不同峰值频率、最大波幅和净空下聚焦波在方箱模型上的砰击压强变化特征。势流模型分析结果发现:水平波浪力随聚焦波峰值频率增大先增大后减小,竖向波浪力随峰值频率增大持续减小,波浪力与聚焦波幅基本呈线性增大关系。
[Abstract]:Offshore Bridge is an important part of the coastal rapid transit network, both offshore low bridge due to deficiencies in the clearance of typhoon (hurricane) serious damage may be caused by giant waves under the impact of the disaster relief and reconstruction work and caused serious economic and social losses. In order to reveal the mechanism of wave bridge structure, determine the factors affecting offshore the bridge structure by wave action, establish a reasonable estimation method of wave force is of great significance to offshore bridge structure security. This thesis focuses on the offshore low bridge superstructure without navigation requirements of the wave force of research, main contents, methods and results are as follows: (1) the 1:10 scale model of wave bridge hydrodynamic test. The model contains a complete girder bridge, two 1/4 length and two piers. The cross test of different wave factors are To the incident wave and oblique incident waves under the action of wave force and bottom pressure of different clearance of upper structure. The experimental results show that the vertical wave force consists of two very high frequency amplitude slamming and low frequency and high frequency components of quasi-static, with horizontal force in the strike force amplitude is very small. When the oblique incident wave when the clearance is small or negative, the maximum wave force of 0 degree angle to produce a wave of incident wave in the bridge superstructure; when the clearance is large, vertical wave force at 15 DEG to reach the maximum wave angle. In addition, there are differences in the spatial distribution of wave force, usually yinglang side bearing bear wave forces big. (2) potential flow theory of positive incident wave under full submerged two-dimensional wave force model based on the upper structure of the bridge. Firstly, the control equation of separation of variables satisfy the boundary conditions, and then use the feature, development Method to determine the velocity potential function of the wave field structure. The potential flow theory by comparing calculation results with experimental results, verify the correctness of the theoretical model. The theoretical calculation results were compared with AASHTO standard method, found the vertical wave force and underestimate overestimate the horizontal wave force phenomenon of the specification, and the calculation results presented the wave force of upper structure of six kinds of AASHTO specification of bridge method based on simple estimating model. (3) the potential flow theory of three-dimensional wave force model under the action of oblique waves, submerged by the upper structure of the bridge. Based on assumption of velocity potential function in the time domain and the bridge span length direction with periodic control from the equation of three-dimensional Laplace equation dimension Helmholtz equation. Firstly, the control equations with unknown coefficients satisfy the boundary conditions, and then use the adjacent subdomains at the interface speed The degree of potential and horizontal velocity continuity for undetermined coefficient velocity potential function, velocity potential function to get the whole basin. Using the linear Bernoulli equation obtained from the velocity field and pressure field, along the area has been under the action of oblique waves, submerged wave force of the upper structure of the bridge. By using the established model to study the influence of wave the geometric angles and superstructure component characteristics of wave force, wave direction is found by wave force zero submerged bridge superstructure when the maximum. (4) carried out a wave with the freak wave on the level of square box test, a submerged wave force box potential flow theory model. First proposed early phase velocity method in the flume test method for generating continuous poly coke wave, and through theoretical and experimental comparison and wavefront spectrum analysis of the effectiveness of the proposed method. Experimental study on the level of the square box model At different frequencies, the maximum amplitude and the clearance under the focusing wave in square box model on the slamming pressure variation. The potential flow model analysis results showed that the horizontal wave force with the focusing wave peak frequency increases and then decreases, with the increase of the peak frequency of vertical wave force decreases continuously, wave force and focusing amplitude linearly the relationship between increased.

【学位授予单位】：哈尔滨工业大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：U441;TV139.26

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