含植物四脚空心块斜坡消浪性能试验研究

该文通过几何缩尺比水槽试验,对比波浪在光滑斜面、四脚空心块斜面和含植物四脚空心块斜面三种斜面上的爬高,研究了不同斜坡的消浪性能,测试了不同波浪周期和波高条件下波浪在斜坡面上的爬升水动力特性和最大爬高变化规律。试验结果表明：在四脚空心块中种植植物可减小波浪对护面块体的直接冲击,降低波浪爬高,对四脚空心块斜坡面的消波性能起到了一定提升作用;在不同斜坡上,无论在规则波还是不规则波条件下,最大波浪爬高与波高均表现出较好的线性关系;在光滑斜面和四脚空心块斜面上,试验所得平均糙渗系数与设计规范中建议的系数基本吻合;根据波浪爬高随波高的变化发现,光滑斜面的变化趋势最陡,块体斜面次之,植物块体斜面最平缓,反映了三种斜坡面糙渗系数的差异;固定浪高情况下,在试验考虑的周期范围内,波浪爬高在三种斜坡面上均随周期的增大而增大,但其增幅并不明显。     

斜坡堤波浪爬高影响因素分析及其外坡轮廓设计

海堤断面型式有斜坡式、陡墙式和混合式之分,不同断面型式波浪爬高的计算方法相异,爬高的大小直接关系到堤顶的高低,进而影响整个断面的尺寸、工程量和投资。为此,本文对斜坡堤波浪爬高的诸影响因素进行分析,以期对复式斜坡堤外坡轮廓尺寸的设计提供一定依据。     

土石坝工程台阶式消浪护坡技术研究

采用数值模拟方法计算土石坝工程台阶式护坡的波浪爬高,分析了台阶式护坡的结构参数、大坝上游坝坡坡度系数、波浪特性参数对台阶式护坡波浪爬高的影响。得出结论:台阶式护坡相比于光面混凝土护坡,平均波浪爬高可减少40%～50%;同一入射波下,坡度系数m相同时,平均波浪爬高及糙率及渗透性系数K△随相对台阶高度h/H的增加先减小后增加再减小;同一入射波下,相对台阶高度h/H相同时,平均波浪爬高随坡度系数m的增加总体呈减小趋势;糙率及渗透性系数K△随坡度系数m的增加呈波动状态。根据计算结果,总结土石坝工程常用坡度系数选用的台阶式护坡结构参数及计算参数。     

非淹没刚性植被影响下孤立波在岸滩上的爬高

为探究海岸刚性植被对海啸波的削弱效应,通过物理模型试验和数值模拟研究了孤立波与不同坡度岸滩上非淹没刚性植被的相互作用问题。物理模型试验在波浪槽中进行,测试了不同的入射波波高、植被密度和岸滩坡度对孤立波爬高的影响,并运用物理模型试验数据校核改进后的Boussinesq方程,得到植被的拖曳力系数。结果表明:拖曳力系数随植被密度的增大而增大,随坡度增大而减小;植被后的无量纲透射波高和无量纲岸滩爬高随着无量纲的入射波高的增大而减小,随着植被密度的增大而减小;当岸滩坡度增大时,无量纲透射波高增大而无量纲爬高并无显著差异。最后根据回归分析得出了岸滩爬高与相对入射波高、植被密度和岸滩坡度的幂函数型经验关系式。     

新型圆弧面防波堤波压力分析

在现有半圆型防波堤研究的基础上,保留半圆型防波堤良好的受力特性,并根据现代水工结构对水环境提出的新要求设计了一种新型的圆弧面防波堤。通过物理模型试验,从相对波高、波陡及开孔率这三个因素对圆弧面的受力性进行了分析。结果表明波浪力随着相对波高的增大而增大;随着波陡的增大波浪力呈现下降趋势,且波陡变化对水平分力影响较小;适当增加开孔率会减小圆弧面上的波压力,而在相对波高较大时开孔率变化对波浪力的影响较小。     

潜堤上波浪传播过程数值研究

以RANS方程结合Level-Set方法为研究基础,采用五阶WENO有限差分格式进行空间离散、三阶TVD Runge-Kutta格式进行时间推进、Level-Set方法追踪波浪与空气间自由面以及解析松弛法来实现数值水槽中的造波消波,建立了一种求解潜堤上波浪传播问题的数值计算模型。选取经典的潜堤上波浪传播物理试验模型对数值模型进行了验证,水位计算结果与试验值吻合较好。进一步研究了波高、潜堤顶部淹没深度以及潜堤坡度等参数对潜堤上波浪传播过程的影响。结果表明:波高越高、淹没深度越浅、潜堤向波坡度越小,波浪受浅水作用越明显;潜堤背波坡度越小,波浪受反浅水作用稍大,但并不明显。     

三孤立波的斜坡爬高特征

该文采用推板式造波机和改进的Goring造波方法在波浪水槽中生成了由三个等波高孤立波组成的波列,首先在坡度为1/10的斜坡上进行了多个孤立波连续爬高的实验研究。实验测量了等波高双孤立波和三孤立波在等水深波浪水槽中传播和在斜坡上的爬高过程,给出了沿程多点浪高仪测量的波面时间序列和高速摄像记录的水线在斜坡上爬高与回落过程影像。分析了来波相对波高和无量纲波峰间距对每个孤立波爬高放大系数的影响。在基于RANS方程和VOF方法的数值波浪水槽中,模拟了三孤立波爬高过程,给出了最大爬高与破碎特征。实验和数值模拟结果表明,孤立波在斜坡上回落时会产生强劲的回流水流,该反向流动导致后随孤立波破碎,消耗波动能量,使得后随孤立波的爬高放大系数明显小于没有回落水流影响的首个孤立波的爬高放大系数。当孤立的波峰间较大时,若来波相对波高较小,后两个的孤立波爬高基本相同;若来波相对波高较大时,第三个孤立波的爬高大于第二个孤立波的爬高。     

荷兰关于波浪爬高和越浪量的计算方法

介绍了荷兰2002年发布的“堤防波浪爬高和越浪”技术报告。报告给出了复杂断面上波浪爬高和越浪量的计算公式,计算中考虑了前滩、边坡糙率、边坡坡度、平台、波浪入射角以及竖墙等因素的影响。所介绍的计算方法对于我国堤防工程等规范的修订有一定的参考意义。     

三孤立波在缓坡上爬高及相互作用的实验研究

海啸波经极缓的大陆架传播至近岸浅水区时可激发由多个孤立波组成的波列。为了研究多个孤立波在斜坡上爬高和相互作用规律,该文选择坡度为1/20的斜坡模型在波浪水槽进行了等波幅三孤立波爬高的物理模型实验。采用大冲程推板式造波机和改进的Goring造波方法,有效地实现了不同波峰间距和不同相对波幅时等波幅三孤立波的造波。采用高速摄像机记录每个孤立波的爬高过程,得到每个孤立波的爬高值;定性分析了爬高过程中孤立波破碎及其相互作用对爬高的影响规律。实验结果表明:第二个孤立波和第三个孤立波受先导波回落水流的影响,破碎位置向离岸方向移动;首波的爬高放大系数基本不受后续来波的影响,其爬高放大系数与同等工况下单孤立波的测量值一致;第二个孤立波和第三个孤立波的爬高放大系数与相邻的波峰间距有关,当波峰间距增大时,爬高放大系数先减少后增加;当波峰间距增至某临界值后时,第三个孤立波的爬高放大系数将大于第二个波的爬高放大系数。最后,依据本次实验结果,提出了等波幅三孤立波在缓坡上爬高的经验公式。     

斜坡堤砌体护面在波浪作用下稳定性的试验研究

本文根据对斜坡堤铺砌块体护面上法向波浪反压力的试验研究,分析了斜坡上最大反压力包络图,指出护坡块体失稳首先发生在破碎水深与打击点之间,该处法向波浪反压力最大。文中探讨了波高、波坦、相对水深、堤坡坡度等参数对该包络图图形的影响;反压力与波面的相位关系等。根据测试数据,应用数理统计方法,给出了反压力包络图的经验表达式和护坡块体最不利受力区域的范围。     

DuaISPHysics：A numerical tool to simulate real breakwaters

The open-source code DualSPHysics is used in this work to compute the wave run-up in an existing dike in the Chinese coast using realistic dimensions, bathymetry and wave conditions. The GPU computing power of the DualSPHysics allows simulating real-engineering problems that involve complex geometries with a high resolution in a reasonable computational time. The code is first validated by comparing the numerical free-surface elevation, the wave orbital velocities and the time series of the run-up with physical data in a wave flume. Those experiments include a smooth dike and an armored dike with two layers of cubic blocks. After validation,the code is applied to a real case to obtain the wave run-up under different incident wave conditions. In order to simulate the real open sea, the spurious reflections from the wavemaker are removed by using an active wave absorption technique.     

椭圆余弦波爬坡与反射的解析研究

本文应用渐近匹配法对椭圆余弦波在中等陡度的岸坡上的爬高和反射进行了解析研究。给出了反射过程中内、外场波形及速度变化的解析表达,得到了坡面上水波最大和最小爬高的规律及它们出现的时间,并进而探讨了坡陡的影响。当波长无限增大时,该解析解收敛于孤立波的情况。这些新的解析结果不仅有助于揭示岸坡对非线性浅水波影响的力学机理,在海岸防护和开发等工程领域中也具有现实的指导意义。     

城市江河防洪堤堤顶高程计算的研究

根据国家颁布的城市防洪有关规范,在城市防洪工程规划和设计时,对防洪堤堤顶高程的计算进行分析,提出了堤防波浪爬高和风壅高度的计算及堤防安全加高值的选用。     

华南沿海防浪林带种植宽度对消浪效果影响的试验研究

相关研究表明:植物带的宽度是影响防浪林消浪效果的主要因素。为此,本文依据华南沿海的实际情况对防浪林树种、波要素、滩地坡度等进行了选取,精细模拟了防浪林带不同宽度时波浪对海堤的冲击及爬高情况,深入分析了破碎波条件下防浪林带宽度对消浪护堤效果的影响,研究成果可供类似人工防浪林设计参考。     

THE VOF METHOD FOR STUDY OF WAVE RUN-UP AND BREAKING ON A SLOPING STRUCTURE

The volume of fluid method(VOF method)for numerical simulations describing wave run-up on a sloping structure including the overturning,breaking and.merging phenomena is presented.The flow motions are governed by the classical,two-dimen-sional Navier-Stokes equation for incompressible fluid.Computational results concerning the time evolution of the free surface and pressure distribution along water bed and slope boundary are given,showing how an initial solitary wave undergoes run-up,overturning,breaking and merging on the slope.It is found that most of the wave energy is lost after the wave breaking and merging.     

AN EXPERIMENTAL OBSERVATION OF A SOLITARY WAVE IMPINGE-MENT,RUN-UP AND OVERTOPPING ON A SEAWALL

A sequence of laboratory experiments using solitary waves was performed to model the effect of leading form of three types of tsunamis(a bore,an impinging wave and an overtopping wave)on a seawall on a sloping beach.The wave evolution process,impinging pressure along the seawall surface,total overtopping discharge behind the seawall and the maximum run-up height on the rear slope were measured and compared.Laboratory data were employed to re-examine relevant empirical formulae in the literature.The effect of the presence of the seawall in reducing maximum run-up height using the present setup was briefly discussed.The present data can be used for calibrating numerical and mathematical models.     

EXPERIMENTAL INVESTIGATION ON WAVE RUN-UP CHARACTERISTICS ALONG COLUMNS AND AIR GAP RESPONSE OF SEMI-SUBMERSIBLE PLATFORM

This article mainly concentrates on a large-volume drilling semi-submersible platform,aiming to reveal wave run-up characteristics along square columns and give the relationship between air gap distributions and wave parameters.The tests with fixed model were conducted firstly on its encountering a series of monochromatic waves.A wide range of wave slope (H /L) were selected to investigate the air gap response in detail.As can be seen,larger wave steepness will generally cause smaller air gap in the same wave period,which indicates nonlinear effects of incoming wave can amplify wave elevation.Model tests with mooring condition were also conducted in the same wave conditions.As was expected,the maximum relative wave elevation reduces obviously compared with the fixed one.However,wave shape close to columns show higher harmonic characteristics due to interaction between waves and the columns of semi-submersible platform.Meaningful conclusions from the model tests are drawn in this article,which is helpful in air gap design of floating offshore platform to a certain extent.In addition,the experimental results will provide an important reference for further research on validation and update of theoretical models of air gap.     

NUMERICAL SIMULATION OF SOLITARY WAVE RUN-UP AND OVER-TOPPING USING BOUSSINESQ-TYPE MODEL

In this article,the use of a high-order Boussinesq-type model and sets of laboratory experiments in a large scale flume of breaking solitary waves climbing up slopes with two inclinations are presented to study the shoreline behavior of breaking and non-breaking solitary waves on plane slopes.The scale effect on run-up height is briefly discussed.The model simulation capability is well validated against the available laboratory data and present experiments.Then,serial numerical tests are conducted to study the shoreline motion correlated with the effects of beach slope and wave nonlinearity for breaking and non-breaking waves.The empirical formula proposed by Hsiao et al.for predicting the maximum run-up height of a breaking solitary wave on plane slopes with a wide range of slope inclinations is confirmed to be cautious.Furthermore,solitary waves impacting and overtopping an impermeable sloping seawall at various water depths are investigated.Laboratory data of run-up height,shoreline motion,free surface elevation and overtopping discharge are presented.Comparisons of run-up,run-down,shoreline trajectory and wave overtopping discharge are made.A fairly good agreement is seen between numerical results and experimental data.It elucidates that the present depth-integrated model can be used as an efficient tool for predicting a wide spectrum of coastal problems.     

水库滑坡涌浪爬坡特征试验研究

由滑坡引起的涌浪灾害不仅严重威胁航运安全,还会冲毁码头、大坝等水工建筑物并造成沿岸居民生命财产的损失。采用物理模型试验的方法对散粒体滑坡涌浪的爬坡特性开展了研究。试验结果表明：影响涌浪爬坡高度的主要因素有滑坡入水速度、滑坡体规模、滑动面倾角、水深、传播距离和爬坡角度等;当涌浪远场传播形态类似椭圆余弦波或孤立波时,涌浪爬坡高度较高,岸坡处水流紊动剧烈,涌浪对岸坡的破坏能力也最强。根据试验结果还建立了近岸坡处涌浪最大波幅计算模型,并结合经典波浪爬坡经验公式推导出了新滑坡涌浪爬坡高度计算公式。以长江新滩滑坡为例,验证了新涌浪爬坡高度计算公式的精度。研究结果能为实际工程中可能存在的滑坡涌浪爬坡灾害范围预测和涌浪避险方案制定等提供一定参考。