Influence of Parapets and Recurves on Wave Overtopping and Wave Loading of Complex Vertical Walls

Coastal structures such as breakwaters are usually studied under wave loading only. However, at several locations also a current is present. For instance, breakwaters along intake and outfall channels of power plants and desalination plants, or structures in regions with important tidal currents, experience wave loading that can be affected by currents. Nevertheless, wave overtopping and rubble mound stability are usually studied under wave loading only; the effects of waves on wave overtopping and rock slope stability have been summarised in many empirical design formulae. None of the existing empirical relations account for the effects of currents on the wave loading and consequently on wave overtopping and rock slope stability. The effects of wave-current interaction on wave overtopping and rubble mound stability has not been quantified, other than that for mild currents these processes are dominated by waves. Therefore, the present study is focussed on wave loading in combination with a strong current. This study is based on physical model tests in a wave-current basin. The results show to what extent wave overtopping and rubble mound stability are affected by wave loading in combination with a current. Wave overtopping and the damage to rock slopes generally reduce due to the presence of a current compared to the situation without a current.

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EXPECTED DISCHARGE OP IRREGULAR WAVE OVERTOPPING

Coastal Engineering Proceedings ◽

10.9753/icce.v11.54 ◽

1968 ◽

Vol 1 (11) ◽

pp. 54 ◽

Cited By ~ 4

Author(s):

Senri Tsuruta ◽

Yoshimi Goda

Keyword(s):

Vertical Wall ◽

Laboratory Data ◽

Irregular Waves ◽

Linear Summation ◽

Wave Overtopping ◽

Irregular Wave ◽

Concrete Blocks ◽

Vertical Walls ◽

Expected Values ◽

Sea Wall

An experiment was carried out on the overtopping of mechanically generated irregular waves over vertical walls. The experimental discharge was almost in agreement with the expected discharge which had been calculated with the wave height histogram and the data of regular wave overtopping based on the principle of linear summation. The expected values of overtopping discharge were calculated for various laboratory data, which had been represented in a unified form of non-dimensional quantities. The calculation has yielded two diagrams of expected overtopping discharge, one for the sea wall of vertical wall type and the othei for the sea wall covered with artificial concrete blocks.

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Wave Overtopping over Coastal Structures with Oblique Wind and Swell Waves

Journal of Marine Science and Engineering ◽

10.3390/jmse6040149 ◽

2018 ◽

Vol 6 (4) ◽

pp. 149 ◽

Cited By ~ 2

Author(s):

Ivo van der Werf ◽

Marcel van Gent

Keyword(s):

Wind Waves ◽

Wave Loading ◽

Coastal Structures ◽

Wave Overtopping ◽

Oblique Wave ◽

Coastal Structure ◽

Test Programme ◽

Specific Direction ◽

Wave Basin

Most guidelines on wave overtopping over coastal structures are based on conditions with waves from one direction only. Here, wave basin tests with oblique wave attack are presented where waves from one direction are combined with waves from another direction. This is especially important for locations where wind waves approach a coastal structure under a specific direction while swell waves approach the coastal structure under another direction. The tested structure was a dike with a smooth and impermeable 1:4 slope. The test programme consisted of four types of wave loading: (1) Wind waves only: “sea” (approaching the structure with an angle of 45°), (2) Wind waves and swell waves from the same direction (45°), (3) Wind waves and swell waves, simultaneously from two different directions (45° and −45°, thus perpendicular to each other), and (4) Wind waves, simultaneously from two different directions (45° and −45°, thus perpendicular to each other). Existing guidelines on wave overtopping have been extended to predict wave overtopping discharges under the mentioned types of wave loading (oblique sea and swell conditions).

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EXPERIMENTAL STUDY ON THE OVERTOPPING BEHAVIOUR OF STEEP SLOPES – TRANSITION BETWEEN MILD SLOPES AND VERTICAL WALLS

Coastal Engineering Proceedings ◽

10.9753/icce.v33.structures.61 ◽

2012 ◽

Vol 1 (33) ◽

pp. 61

Author(s):

Lander Victor ◽

Peter Troch

Keyword(s):

Slope Angle ◽

Breaking Waves ◽

The Other ◽

Prediction Methods ◽

Wave Overtopping ◽

Wave Energy Converters ◽

Vertical Walls ◽

The One ◽

Steep Slopes ◽

Existing Data

Extensive knowledge is available on the overtopping behaviour of traditional smooth impermeable sea defence structures, such as mildly sloping dikes and vertical walls, both typically featuring a high crest freeboard to reduce wave overtopping. A particular design application emerges in the development of wave energy converters of the overtopping type, where maximisation of wave overtopping is required, i.e. smooth impermeable steep sloping structures with low crest freeboards subjected to non-breaking waves. To date, only relatively limited knowledge is available on the overtopping behaviour of those structures. In this study, the average overtopping rate obtained from new experiments has been analysed and compared with existing prediction methods. This study contributes to a better knowledge on the overtopping behaviour of the steep low-crested structures, which is positioned in between that of mildly sloping dikes and vertical walls on the one hand, and in between that of structures with zero crest freeboards and relatively large crest freeboards on the other hand. The existing prediction methods seem unable to predict the significant effects of the slope angle and small relative crest freeboards on the average overtopping rate accurately. Therefore, a new set of prediction formulae is proposed based on the new experiments combined with existing data from literature. These formulae include wave overtopping at vertical walls subjected to non-impacting waves and at structures with zero crest freeboard.

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IRREGULAR WAVE OVERTOPPING AT VERTICAL WALLS - LEARNING FROM REGULAR WAVE TESTS

Coastal Engineering 2006 ◽

10.1142/9789812709554_0397 ◽

2007 ◽

Author(s):

Karl-Fr. Daemrich ◽

Jens Meyering ◽

Nino Ohle ◽

Claus Zimmermann

Keyword(s):

Regular Wave ◽

Wave Overtopping ◽

Irregular Wave ◽

Vertical Walls

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Determination of Semi-Empirical Models for Mean Wave Overtopping Using an Evolutionary Polynomial Paradigm

Journal of Marine Science and Engineering ◽

10.3390/jmse8080570 ◽

2020 ◽

Vol 8 (8) ◽

pp. 570

Author(s):

Corrado Altomare ◽

Daniele B. Laucelli ◽

Hajime Mase ◽

Xavi Gironella

Keyword(s):

Polynomial Regression ◽

Structural Parameters ◽

Full Range ◽

Empirical Formulas ◽

Wave Overtopping ◽

Evolutionary Polynomial Regression ◽

Local Wave ◽

Vertical Walls ◽

Local Water ◽

Semi Empirical

The present work employs the so-called Evolutionary Polynomial Regression (EPR) algorithm to build up a formula for the assessment of mean wave overtopping discharge for smooth sea dikes and vertical walls. EPR is a data-mining tool that combines and integrates numerical regression and genetic programming. This technique is here employed to dig into the relationship between the mean discharge and main hydraulic and structural parameters that characterize the problem under study. The parameters are chosen based on the existing and most used semi-empirical formulas for wave overtopping assessment. Besides the structural freeboard or local wave height, the unified models highlight the importance of local water depth and wave period in combination with foreshore slope and dike slope on the overtopping phenomena, which are combined in a unique parameter that is defined either as equivalent or imaginary slope. The obtained models aim to represent a trade-off between accuracy and parsimony. The final formula is simple but can be employed for a preliminary assessment of overtopping rates, covering the full range of dike slopes, from mild to vertical walls, and of water depths from the shoreline to deep water, including structures with emergent toes.

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DEVELOPMENT OF WAVE OVERTOPPING MODEL INCORPORATING WATER OVERFLOW FOR VERTICAL WALLS

Coastal Engineering Proceedings ◽

10.9753/icce.v36.waves.3 ◽

2018 ◽

pp. 3

Author(s):

Yoji Tanaka ◽

Katsuyuki Suzuyama ◽

Naoto Higuchi ◽

Hidenori Shibaki

Keyword(s):

Experimental Data ◽

Storm Surge ◽

Vof Method ◽

New Wave ◽

Wave Overtopping ◽

Hydraulic Experiment ◽

Data Provider ◽

Shallow Area ◽

Vertical Walls ◽

Water Overflow

In a situation where water overflow occurs on the seawalls due to a storm surge, generally it is high waves that cause wave overtopping. However, it is common that overflow and overtopping are modeled as separate phenomena, in a situation where both phenomena occur at the same time, the amount of water exceeding the seawalls may not be evaluated correctly. The purpose of this research is to develop a new wave overtopping model including the water overflow for vertical seawalls. The new overtopping model improved the overtopping model of Goda (Goda, 2008: Goda08 model). Goda08 model was developed to adapt for various seawall forms. Goda (2008) insisted it was more accurate than EurOtop model. Nonetheless, Goda08 model has a problem of overestimation in shallow area. Therefore, we tuned the parameters again. It is difficult to reproduce the situation where the overtopping and overflow occur at the same time in a hydraulic experiment. Consequently, CADMAS-SURF which is based on the 2-dimensional non-compressive fluid using the VOF method was used as an experimental data provider for comparative verification of the model.

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WAVE OVERTOPPING AT DYKES WITH TOPPED VERTICAL WALL - IMPACTS OF OBLIQUE WAVE ATTACK

Coastal Engineering Proceedings ◽

10.9753/icce.v33.structures.60 ◽

2012 ◽

Vol 1 (33) ◽

pp. 60

Author(s):

Nils B. Kerpen ◽

Torsten Schlurmann

Keyword(s):

Numerical Models ◽

Vertical Wall ◽

Coastal Protection ◽

Wave Spectra ◽

Wave Overtopping ◽

Oblique Wave ◽

Wave Basin ◽

Vertical Walls ◽

The Mean ◽

Analytical Approaches

Hydraulic model tests at a scale of 1:10 are carried out in a 40 m x 25 m wave basin with a state-of-the-art 3D wave generator in order to collect wave overtopping data at vertical walls and dykes with topped vertical walls. Wave conditions in the near field of the structures, velocities under waves and the mean overtopping discharge are measured. The experiments have been commissioned by the Lower Saxony Water Management, Coastal Defense and Nature Conservation Agency (NLWKN) with the purpose to deliver essential overtopping data for validation of numerical models. Two main geometries are analyzed – each for two specific wave spectra. Overtopping rates are investigated with respect to the remaining freeboard height Rc and the influence of oblique wave attack β{0°, 10°, 30°, 40°, 50°, 60°}. Results are compared with existing analytical approaches. As expected for this special geometrical coastal protection structure, it is examined that overtopping discharges increase with decreasing remaining freeboard. Intensity of the reduction is more dependent on the wave spectra than on the dyke geometry. Mean wave overtopping rate increases with decreasing relative water depth Hm0/d directly in front of the vertical wall. Furthermore, the mean wave overtopping rates decrease with an increasing angle of wave attack β. The correlation between mean wave overtopping rate and freeboard height is given in four newly adapted design formulas, describing the overtopping performance of the two discussed dyke geometries with topped vertical walls.

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