【作者】 张少华；

【导师】 马玉祥；

【作者基本信息】 大连理工大学 ， 港口、海岸及近海工程， 2020， 硕士

【摘要】 直立式结构是海洋结构物中常见的工程结构形式,波浪在结构物上的爬高是一种常见的物理过程。当波浪爬高大于入射波振幅的2倍时,称为极端波浪爬高。极端的波浪爬高极可能会导致人员伤亡、结构损坏甚至结构功能丧失。因此,对于直立结构的安全设计,需要考虑极端波浪爬高的影响,但是目前规范中基本未考虑直立结构的极端波浪爬高。本文基于非静压表面流模型建立了三维数值波浪水池,进行了正向入射和斜向入射规则波在直立结构物上爬高的数值模拟实验,研究了两种不同类型的极端波浪爬高现象,并系统研究了波陡、水深及入射角度对波浪在直立结构物上的极端爬高的影响。当波浪正向入射与直立结构相互作用时,由于三阶共振相互作用,在直立结构上产生极端的波浪爬高。通过不同水深、波陡的正向入射规则波与直立板相互作用,波浪爬高在直立板上的分布差异较大。首先,波浪爬高最大放大率随波陡和水深的增大而增大。其次,随着波陡、水深的增大,最大波浪爬高放大率移向直立板里侧的趋势越来越显著。最重要的是,直立板前侧波面的最大高程是入射波的4倍,远大于线性理论的2倍预测。当波浪以小于某一临界角度入射时,直墙处除入射波与反射波之外,还存在着沿墙发展的第三组波,称为Stem波,这一波浪现象称为Mach反射。因此,本文研究了斜向入射规则波在直墙上的极端波浪爬高,主要研究了入射角度、波陡及水深对Stem波的幅度及宽度的影响。首先,考虑入射角度的影响。当入射角度小于20°,直墙处波浪爬高放大率沿程单调增加,增长速度随入射角度线性增大。波浪爬高最大放大率的位置随着入射角度的增加而降低。Stem波宽度随着入射角度的增大而减小,当入射角度较大时,沿直墙法线方向会出现典型的驻波模式。其次,考虑波陡的影响。当入射角度较小时,沿程波浪爬高放大率随波陡是严格增大的,随着入射角度的增大,波浪爬高放大率对于波陡的依赖性降低。波浪爬高放大率的增长速度随着波陡的增加而降低,而Stem波宽度随着波陡的增大而增大。最后,考虑水深的影响。水深从浅水到有限水深时,沿程波浪爬高放大率随着相对水深的减小而增大,而Stem波宽度随着相对水深的增大而增大。当水深达到深水条件后,直墙处波浪爬高放大率最大值及Stem波宽度保持不变。结果表明,无论是正向入射还是斜向入射规则波在直立结构物上的极端波浪爬高都大于线性理论预测的2倍。因此,直立结构安全设计时,需要考虑非线性波浪爬高的影响。并且本文研究了非线性波浪在直立结构物上的爬高,基于波浪爬高的影响规律,可以为直立结构物的安全设计和合理选址提供技术支持。更多还原

【Abstract】 Vertical structures are common engineering structure in marine construction.Wave run up on the vertical structure is a common physical process.Extreme wave run up is defined when the elevation of wave run up is greater than 2 times amplitude of incident wave.Extreme wave run up may cause casualties,structural damage or even loss of structural function.Therefore,the effect of wave run up needs to be considered for the safety design of vertical structures.However,Extreme wave run up of vertical structures is not considered in the current design code.In this paper,a three-dimensional numerical wave tank based on a fully non-hydrostatic free surface flow model is established,to carry out relevant numerical simulation experiments on the normal and oblique incidence regular wave run up on a vertical structure.Two different types of extreme wave run up phenomena are studied,and the effects of wave steepness,water depth and incident wave angle on wave run up are systematically studied.Due to the third-order resonant interaction,extreme wave run up is generated on the vertical structure when the wave is normally incident and interacts with the vertical structure.It is found that the variations of wave run up along the vertical plate are discrepant in different wave steepness and water depths.Firstly,the maximum amplification of wave run up increases with the wave steepness and water depth.Then,the tendency of maximum amplification of wave run up to move to the inner side of the vertical plate becomes more and more significant with the wave steepness and water depth increasing.Most important of all,the largest wave surface elevations at the weather side on vertical plate can reach up to about 4 times of the incident wave,much larger than the 2 times predicted from linear theory.When wave is incident less than critical angle,in addition to incident and reflected waves at the vertical wall,there is third wave developed along the wall,called the Stem wave,and the wave’s phenomenon is called Mach reflection.Therefore,extreme wave run up of obliquely incident regular wave on vertical wall is studied,and this part mainly studies the effects of incident wave angle,wave steepness and water depth on wave run up.Firstly,the effect of incident wave angle is considered.The amplification of wave run up at the vertical wall increases monotonously,and the amplitude growth rate of Stem wave increases linearly with incident angle when the angle is less than 20°.The location of maximum the amplification of wave run up decreases with increasing incident angle.The width of Stem wave decreases with increasing incident angle.A typical standing wave pattern will appear along the normal to the vertical wall when the incident angle is large.Next,the effect of wave steepness is considered.When the incident angle is small,the amplification of wave run up along the wall increases strictly with the wave steepness.As the incident angle increases,the dependence of the amplification of wave run up on the wave steepness decreases.The growth rate of the amplification of wave run up decreases with wave steepness increasing,while the Stem wave width increases.Then,the effect of water depth is considered.When the water depth is from shallow to finite water depth,the amplification of wave run up along the wall increases with the decrease of relative water depth,but the width of Stem wave increases with the increase of relative water depth.The maximum amplification of wave run up and the width of the Stem wave remain at a constant value in deep water conditions.The results show that the extreme run up of the normal or oblique incidence of regular waves on the vertical structure is greater than the linear theory predicted 2 times.Therefore,it is necessary to take into account the effect of nonlinear wave run up for the safe design of vertical structures.In addition,this paper studies the extreme wave run up on vertical structures.Based on the influence of wave run up,it can provide technical support for the safe design and reasonable location of vertical structures.更多还原