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Within the CLASH project, wave overtopping at the vertical seawall at Samphire Hoe was measured by HR Wallingford (HRW), and compared laboratory tests in 2 & 3 dimensions carried out at the University of Edinburgh and HRW. At Samphire Hoe, overtopping volumes were captured in three volumetric tanks capable of measuring wave-by-wave and total overtopping volumes. The three tanks were placed progressively farther back from the seawall edge so that the spatial distribution of the overtopping discharges could be determined. The field measurement equipment was successfully deployed on three occasions, and measured overtopping discharges ranged from that barely considered to be hazardous to the public to over q = 3.0 l/s/m. The 2d testing at Edinburgh was modelled at a scale of 1:40, and the 3d model at HRW was modelled at 1:20. For both sets of laboratory tests, a range of conditions, representative of the storm wave conditions and water levels, was reproduced in addition to a set of parametric conditions. The storm conditions allowed a direct comparison between the field and laboratory measurements, and the parametric conditions were used to test the generic overtopping behaviour of the structure. For both sets of laboratory tests, mean overtopping discharges and the spatial distribution were measured separately. Analysis of the distribution data relates the proportion of the discharge that has landed as a function of (x / Lo); where x is the distance behind the crest, and Lo is the offshore wavelength. Analysis of the field, 2d & 3d laboratory data, and empirical prediction methods have not identified any scale effects for overtopping discharges at vertical and near-vertical seawalls. 相似文献
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漫堤是天文潮、风暴潮与海浪等物理要素作用于海堤后海水翻越海堤的物理过程。本文利用天文潮-风暴潮-台风浪耦合模式(ADCIRC+SWAN)、基于非结构三角形网格和高分辨率地理数据(海堤位置和高程、岸线和水深等)构建福建沿海精细化漫堤风险等级评估系统。该系统在近岸网格分辨率最高达50m,可精确刻画福建沿海复杂地形。利用模拟的水位与海浪参数,采用波浪爬高公式计算得到各海堤堤前波浪爬高。按照总水位与波浪爬高之和与海堤高程的对比,将漫堤风险分为五个等级。对2013年的超强台风天兔过程进行后报检验。结果显示,该系统计算的漫堤情况与灾后调查的漫堤实况基本一致,结果准确,说明本研究中采用的漫堤风险评估标准和方法是可行的。在此基础上,设计了4种不同的台风强度等级,对福建沿海206条海堤进行了漫堤风险等级评估,探究台风强度对漫堤风险的影响。结果表明:波浪爬高对漫堤风险的影响高于单纯的风暴潮增水;风暴潮增水随台风强度的增强增量较小,对于漫堤的风险影响较小;福建沿海波浪爬高普遍较高,随着台风强度的增强,波浪爬高会显著增加漫堤的风险等级,且应重视台风浪对海堤造成的冲击所导致的溃堤灾害。本研究可为沿海防灾减灾提供科学依据。 相似文献
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灾害性波浪是中国沿海地区最具破坏性的自然灾害之一。采用开源程序OpenFOAM中interFoam求解器,对低顶海堤（在风暴潮和海平面上升情况下所面临的不利工况）的孤立波越浪特性开展数值模拟研究。通过孤立波冲击海堤的基准算例,验证模型在模拟波浪爬升和越浪过程中大变形波面以及剧烈波浪力方面的精度。基于验证的数值模型,对孤立波在低顶海堤上的越浪特征以及防浪墙高度对越浪的影响开展参数化研究。结果表明堤顶超高减小导致更为剧烈的越浪。针对尚无低顶海堤孤立波越浪量经验公式的问题,提出新的适用于堤顶超高小或为0的孤立波越浪量经验公式。此外,研究发现增加防浪墙高度可有效减少越浪,但防浪墙所受的波浪力也增大。综合考虑防浪墙减少越浪以及自身所受波浪力,针对文中研究采用的海堤截面和波浪条件,建议无量纲防浪墙高度取为1.00。 相似文献
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准确确定越浪量对于斜坡堤设计有重要意义。利用格子Boltzmann方法(LBM),并采用主动吸收式速度入口造波、出流边界消波、VOF方法追踪自由表面以及静态Smagorinsky模型模拟紊流运动,建立二维数值波浪水槽,对光滑斜坡堤上规则波与不规则波越浪进行数值模拟。模拟结果与试验值及其他数值模型结果比较表明,二维LBM数值波浪水槽具有模拟斜坡堤越浪的能力,但对于破碎较为剧烈的越浪过程模拟,该模型还存在一定的不足,未来可从提高自由表面模型精度等方面进一步改善其性能。 相似文献
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Numerical study of combined overflow and wave overtopping over a smooth impermeable seawall 总被引：1，自引：0，他引：1
A numerical wave flume is used to investigate the discharge characteristics of combined overflow and wave overtopping of impermeable seawalls. The numerical procedure computes solutions to the Reynolds-averaged Navier–Stokes equations and includes the generation of an irregular train of waves, the simulation of wave breaking and interaction with a sloping, impermeable wall. The numerical model is first tested against published experimental observations, approximate analytical solutions and empirical design formulae for the cases of pure overflow and pure overtopping. A sequence of numerical experiments simulating combined overflow and overtopping are described. The results are used to determine empirical discharge formulae of the form used in current practice. 相似文献
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《Coastal Engineering》2006,53(9):723-735
The paper presents an incompressible Smoothed Particle Hydrodynamics (SPH) model to investigate the wave overtopping of coastal structures. The SPH method is a grid-less Lagrangian approach which is capable of tracking the large deformations of the free surface with good accuracy. The incompressible algorithm of the model is implemented by enforcing the constant particle density in the pressure projection. The SPH model is employed to reproduce a transient wave overtopping over a fixed horizontal deck and the regular/irregular waves overtopping of a sloping seawall. The computations are validated against the experimental and numerical data and a good agreement is observed. The SPH modelling is shown to provide a promising tool to predict the overtopping characteristics of different waves. The present model is expected to be of practical purpose if further improvement in the spatial resolution and CPU time can be adequately made. 相似文献
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《Coastal Engineering》2005,52(7):633-645
New experimental laboratory data are presented on swash overtopping and sediment overwash on a truncated beach, approximating the conditions at the crest of a beach berm or inter-tidal ridge-runnel. The experiments provide a measure of the uprush sediment transport rate in the swash zone that is unaffected by the difficulties inherent in deploying instrumentation or sediment trapping techniques at laboratory scale. Overtopping flow volumes are compared with an analytical solution for swash flows as well as a simple numerical model, both of which are restricted to individual swash events. The analytical solution underestimates the overtopping volume by an order of magnitude while the model provides good overall agreement with the data and the reason for this difference is discussed. Modelled flow velocities are input to simple sediment transport formulae appropriate to the swash zone in order to predict the overwash sediment transport rates. Calculations performed with traditional expressions for the wave friction factor tend to underestimate the measured transport. Additional sediment transport calculations using standard total load equations are used to derive an optimum constant wave friction factor of fw = 0.024. This is in good agreement with a broad range of published field and laboratory data. However, the influence of long waves and irregular wave run-up on the overtopping and overwash remains to be assessed. The good agreement between modelled and measured sediment transport rates suggests that the model provides accurate predictions of the uprush sediment transport rates in the swash zone, which has application in predicting the growth and height of beach berms. 相似文献
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Under the numerical modelling work package of the EU funded CLASH project, the time accurate, free surface capturing, incompressible Navier–Stokes solver AMAZON-SC has been applied to study impulsive wave overtopping at Samphire Hoe, near Dover in the United Kingdom. The simulations show that the overtopping process on this vertical, sheet pile, seawall is dominated by impulsive, aerated, near vertical overtopping jets. In order to perform the simulations AMAZON-SC has been extended to incorporate an isotropic porosity model and for validation purposes the solver has been applied to study overtopping of a low crested sea dike and a 10:1 battered wall. The results obtained for the battered wall and Samphire Hoe tests are in good agreement both with predicted overtopping discharges calculated using the UK overtopping manual and with available experimental results. 相似文献
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Li Yan-ting Zeng Cheng-jie Yi-han Zhao Hu Po Sun Tian-ting Hou Yi-jun Mo Dong-xue Wang Deng-ting 《中国海洋工程》2022,36(3):413-426
Storm surges are cataclysmic natural disasters that occur along the coasts and are usually accompanied by large waves. The effects of coupled storm surges and waves can pose a significant threat to coastal security. Previous laboratory studies on the effects of storm surges and waves on coastal structures have typically utilized steady water levels and constant wave elements. An indoor simulation of the coupled processes of tides and waves is developed by adding a tide generation system to an existing laboratory wave basin to model continuous dynamic tide levels so that tide generation and wave-making occur synchronously in the pool. Specific experimental methods are given, which are applied to further study waves overtopping on artificial sea dikes and coastal flooding evolution under the coupled actions of tides and waves. The results of the overtopping discharge obtained by the test with a dynamic water level are compared with those obtained from steady water level tests and the existing empirical formula. In addition, the impacts of ecological coastal shelterbelts and structures on coastal flood processes and distributions are also investigated. The proposed simulation methods provide a new approach for studying the effects of storm surges and waves on coastal areas. The study also aims to provide a reference for coastal protective engineering.
相似文献12.
基于非静压单相流模型NHWAVE建立了高精度数值波浪水槽。通过设计不同的计算工况,系统研究了非淹没刚性植物对海啸作用下海堤周围水动力特性的影响。着重分析了不同入射波高、不同植物分布密度以及不同植物分布宽度条件下海啸波沿程波形特征以及海堤堤顶越浪流空间分布特征。结果表明:不同入射波高、植物分布密度以及植物宽度条件下,堤顶流厚度和水体流速具有明显单调的变化趋势,并且随着植物分布密度和宽度增大,波能衰减增大;随着入射波非线性增强,植物分布密度和分布宽度对堤顶前段水流厚度的影响也随之增强,而对堤顶后段水流厚度的影响则减弱,且堤顶后缘水流厚度约为堤顶前缘厚度的二分之一;在波浪非线性较大情况下,植物的存在对堤顶流速度的空间分布趋势几乎没有影响,但相对堤顶流速度增加程度均大于无植物情况,且堤顶后缘水流速度约为堤顶前缘的1.6倍。 相似文献
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浙江省海塘塘顶高程的确定 总被引：10，自引：1，他引：10
介绍了浙江省海塘塘顶高程确定时所涉及的波浪爬高，越浪量等的计量，同时分析了1997年后浙江省海塘塘顶高程确定的方法，由已建海塘的塘顶高程分析可见，在背水坡和塘顶有保护措施的情况下，采用允许最大越波流量来控制海塘塘顶高程，可适当降低塘身高度。 相似文献
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Riccardo Briganti Giorgio Bellotti Leopoldo Franco Julien De Rouck Jimmy Geeraerts 《Coastal Engineering》2005,52(12):351-1174
This paper describes a new station for full-scale measurement of wave overtopping at the Rome yacht harbour rubble mound breakwater in Ostia (Italy) and the results of the successful first measurement campaign carried out during the winter season 2003–2004. The equipment and the research activities were supported by the EU project CLASH, focusing on scale effects for wave overtopping at coastal structures. The site is characterized by a very small tidal range, a long shallow foreshore and depth-limited breaking waves which interact with a shallow sloping porous rock structure. Overtopping water is collected by a steel tank installed on the crown slab behind the parapet wall. The measurement of water level variation inside the tank by means of two pressure transducers allows the calculation of individual overtopping volumes. Incident waves, sea levels and wind are also measured. During seven independent storms, more than 400 individual overtopping events were recorded and about 86 h of valid data are available. This extensive dataset is presented, discussed and then used for comparison with two commonly used overtopping prediction formulae based on small-scale model tests showing their tendency to underestimate the prototype results. A strong correlation between the hourly mean overtopping discharge and corresponding maximum volume is also presented. The paper generally confirms the validity of the approach used in Troch et al. (2004) [Troch, P., Geeraets, J., Van de Walle, B., De Rouck, J., Van Damme, L., Allsop, W., Franco, L., 2004. Full-scale wave overtopping measurements on the Zeebrugge rubble mound breakwater. Coastal Engineering 51, 609–628] for field measurement of wave overtopping. 相似文献
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Dike resilience against wave overtopping has gained more and more attention in recent years due to the effect of expected future climate changes. The overtopping flow velocities and flow depths on dikes have recently been studied in 2D small-scale experiments. This has led to semi-empirical formulae for the estimation of flow depths and flow velocities across a dike. The results have been coupled to the actual erosion of the landward dike slope determined by full-scale 2D tests using the so-called “Overtopping Simulator”. This paper describes the results from 96 small-scale tests carried out in a shallow water basin at Aalborg University to cover the so far unknown 3D effects from oblique long-crested and short-crested waves. Based on results from the laboratory tests, expansions are proposed to the existing 2D formulae so as to cover oblique and short-crested waves. The wave obliquity is seen to significantly reduce the overtopping flow velocities and flow depths on especially the landward slope of a sea dike. Moreover, the tests showed that the average flow directions on the dike crest from oblique long-crested and short-crested waves correspond approximately to the incident wave direction. Flow depths and the squared flow velocities on the dike are concluded to be Rayleigh-distributed in case of both long-crested and short-crested waves for all considered incident wave obliquities. Findings in the present paper are needed to obtain more realistic estimates of dike erosion caused by wave overtopping. 相似文献
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A statistical model is developed to predict wave overtopping volume and rate of extreme waves on a fixed deck. The probability density function for the volume and rate of overtopping water are formulated based on the truncated Weibull distribution with the assumption of local sinusoidal profile for small amplitude waves. Sensitivity to the wave nonlinearity parameter and deck clearance is discussed. The statistical model is compared to laboratory data of the instantaneous free surface elevation measured in front of a fixed deck, and overtopping volume and overtopping rate measured at the leading edge of the deck. The statistical theory compared well with the measured exceedance probability seaward of the deck. The model prediction of the exceedance probability of deck overtopping gave qualitatively good agreement for large overtopping values. 相似文献
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The hydrodynamic performance of vertical and sloped plane, dentated and serrated seawalls were investigated using physical model studies. Regular and random waves of wide range of heights and periods were used. Tests were carried out for different inclinations of the seawall (i.e. θ=30, 40, 50, 60 and 90°) and for a constant water depth of 0.7 m. The wave reflection was measured to assess the dissipation character of the seawalls. It was observed that the serrated seawall was superior to the plane and dentated seawall in reducing the wave reflection. Even for the vertical case, the coefficient of reflection due to regular waves for dentated seawall ranged from 0.6–0.99 and for the vertical serrated seawall it was 0.45–0.98, whereas for the vertical plane wall, it was almost 1.0. It was found that the characteristic dimension of the seawall (i.e. L/W) and the relative water depth (i.e. d/L) were better influencing parameters compared to the conventionally used surf similarity parameter ‘ξ’ (ξ=tan θ/(Hi/L)0.5) in predicting the reflection from the dentated and serrated seawall, where L is the local wave length, W the width of the dent along the length of the seawall slope, d the water depth at the toe and Hi is the incident wave height. A similar trend was observed for the random waves too. The reduction in the wave reflection due to random waves for the dentated seawall as compared to the plane seawall was about 18% and for the serrated seawall, it was 20%. It was observed that the reflection due to random waves was lesser for all the three different walls than the regular waves, due to the mutual interaction of random waves. Multiple regression analysis on the measured data points was carried out and predictive equations for the reflection coefficient were obtained for both regular and random waves. This study will be useful in the design of energy dissipating type vertical quay walls in ports and harbours, sloped seawalls for shore protection from erosion and sloped caisson as breakwaters. Comparison of predictive formulae with the experimental results revealed that the prediction methods were good enough for practical purposes. 相似文献
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珊瑚岛礁海岸波流动力复杂、地貌形态特殊、工程响应未知, 波浪传播变形和波生环流对建筑物安全、地形地貌演变、防灾减灾和生态环境保护都有重要影响。本文从大范围大洋海脊导波与岛礁波浪俘获、中等尺度的礁坪-潟湖-裂口系统波流特性、建筑物前沿的局部波流特性及工程响应等三种不同空间尺度上综述了波流运动特性研究的新进展, 主要包括深水大范围的海脊波浪引导与岛礁波浪俘获的理论解析、礁坪-潟湖-裂口系统整体物理模型实验、基于大水槽实验的建筑物影响下波流演化过程及越浪量和波浪力计算方法, 并提出亟需深入研究的重点内容。 相似文献
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The paper describes the results of a two-dimensional (2-D) numerical modelling investigation of the functionality of rubble mound breakwaters with special attention focused on wave overtopping processes. The model, COBRAS-UC, is a new version of the COBRAS (Cornell Breaking Waves and Structures) based on the Volume Averaged Reynolds Average Navier–Stokes (VARANS) equations and uses a Volume of Fluid Technique (VOF) method to capture the free surface. The nature of the model equations and solving technique provides a means to simulate wave reflection, run-up, wave breaking on the slope, transmission through rubble mounds, overtopping and agitation at the protected side due to the combined effect of wave transmission and overtopping. Also, two-dimensional experimental studies are carried out to investigate the performance of the model. The computations of the free surface and pressure time series and spectra under regular and irregular waves, are compared with the experimental data reaching a very good agreement. The model is also used to reproduce instantaneous and average wave overtopping discharge. Comparisons with existing semi-empirical formulae and experimental data show a very good performance. The present model is expected to become in the near future an excellent tool for practical applications. 相似文献