scholarly journals OBLIQUE WAVE ATTACK ON CUBE AND ROCK ARMOURED RUBBLE MOUND BREAKWATERS

2011 ◽  
Vol 1 (32) ◽  
pp. 34
Author(s):  
Guido Wolters ◽  
Marcel Van Gent
Keyword(s):  
Double Layer ◽  
Single Layer ◽  
Rock Slopes ◽  
Mass Reduction ◽  
Oblique Wave ◽  
Wave Basin ◽  
Rubble Mound ◽  
The Stability ◽  
Observed Damage ◽  
Rubble Mound Breakwaters

Stability formulae for armour layers of rubble mound breakwaters are usually being applied assuming perpendicular wave attack. Often it is assumed that for oblique wave attack the reduction in damage compared to perpendicular wave attack is small. This seems however a very conservative assumption. Wave basin tests at Deltares provide information to assess the effects of oblique waves on the stability of rock slopes and cube armoured rubble mound breakwaters. This includes cubes in a single layer and cubes in a double layer. The results show that the few available formulae that include wave obliquity underestimate the effects of oblique wave attack; the observed damage to breakwaters with armour layers of rock and cubes is lower and therefore new stability increase factors and mass reduction factors have been developed. The tests were performed for wave directions between perpendicular (0) and 70. The results show that large potential savings in diameter and mass can be obtained for large angles of wave obliquity.

scholarly journals STABILITY OF RUBBLE MOUND BREAKWATERS WITH A BERM

2012 ◽  
Vol 1 (33) ◽  
pp. 10
Author(s):  
Marcel Van Gent ◽  
Gregory M. Smith ◽  
Ivo Van der Werf
Keyword(s):  
Rock Slope ◽  
Slope Angle ◽  
Rock Slope Stability ◽  
Rock Slopes ◽  
Test Results ◽  
Physical Model Tests ◽  
Rubble Mound ◽  
The Stability ◽  
Rubble Mound Breakwaters ◽  
Rock Size

The stability of rock slopes with a horizontal berm has been studied by means of physical model tests. This paper is focussed on the rock slope stability of the slopes above and below the berm. By applying a berm the rock size can be reduced compared to the required rock size for a straight slope without a berm. This reduction can be significant for the slope above the berm. The influence of the slope angle (1:2 and 1:4), the width of the berm, the level of the berm, and the wave steepness have been investigated. Based on the test results prediction formulae have been derived to quantify the required rock size for rubble mound breakwaters with a berm.

scholarly journals STABILITY OF HIGH DENSITY CUBES IN RUBBLE MOUND BREAKWATERS

2020 ◽  
pp. 4
Author(s):  
Yalcin Yuksel ◽  
Marcel van Gent ◽  
Esin Cevik ◽  
H. Alper Kaya ◽  
Irem Gumuscu ◽  
...  
Keyword(s):  
Relative Density ◽  
Slope Angle ◽  
High Density ◽  
Experimental Results ◽  
Normal Density ◽  
Stability Number ◽  
Damage Initiation ◽  
Rubble Mound ◽  
The Stability ◽  
Rubble Mound Breakwaters

The stability number for rubble mound breakwaters is a function of several parameters and depends on unit shape, placing method, slope angle, relative density, etc. In this study two different densities for cubes in breakwater armour layers were tested to determine the influence of the density on the stability. The experimental results show that the stability of high density blocks were found to be more stable and the damage initiation for high density blocks started at higher stability numbers compared to normal density cubes.

scholarly journals Design of Rock Armoured Single Layer Rubble Mound Breakwaters

1999 ◽  
Author(s):  
T. Hald ◽  
A. Tørum ◽  
T. Holm–Karlsen
Keyword(s):  
Single Layer ◽  
Rubble Mound ◽  
Rubble Mound Breakwaters

scholarly journals A SIMPLE MATHEMATICAL MODEL OF WAVE MOTION ON A RUBBLE MOUND BREAKWATER SLOPE

2011 ◽  
Vol 1 (8) ◽  
pp. 26
Author(s):  
Anton Brandtzaeg
Keyword(s):  
Mathematical Model ◽  
Wave Motion ◽  
Point Of View ◽  
Glass Panel ◽  
Wave Channel ◽  
First Approximation ◽  
Rubble Mound ◽  
The Stability ◽  
Rubble Mound Breakwaters ◽  
Made In

In the improvement of design criteria for the layer of cover blocks on rubble mound breakwaters important advance has been made in recent years (l), (2), (3). Still, some points seem to require further study, among them the effect of the specific weights of block material and fluid on the stability of the cover. In this respect the magnitude of the fluid accelerations involved, of which little information is available may be of some importance. For evaluation of the acceleratic as well as for other purposes, a roughly approximate mathematic description of the motion of the water rushing up and down the breakwater front may be of some use. This motion certainly is neither steady nor uniform. Visual and photographic observation through the glass panel a wave channel seems to indicate, however, that unsteadiness the more important characteristic of the motion during the up and downrush proper. It seems reasonable, therefore, to att€ a first approximation to a description of the motion by neglecting, to a certain extent, its non-uniformity. Necessarily, the same time also the requirement of continuity must be partly disregarded. In the following a mathematical model based on this point of view is presented for consideration. It is believed that by means of this model values of displacements, velocity and accelerations can be calculated, which may reasonably be considered as useful, although quite rough, approximations t< the actual values. For a few particular cases, experimental evidence is reported. The model has reference only to the up- and downrush proper, that is, to the motion of the water above some limit level, at or somewhat below the Still Water Line (referred t< hereafter as the StflL). The motion below this level, where tl downrush meets the oncoming next wave, could hardly be conee of as being uniform.

Artificial Intelligence and Rubble-Mound Breakwater Stability

2012 ◽  
pp. 1499-1506
Author(s):  
Gregorio Iglesias Rodriguez ◽  
Alberte Castro Ponte ◽  
Rodrigo Carballo Sanchez ◽  
Miguel Ángel Losada Rodriguez
Keyword(s):  
Physical Model ◽  
Model Tests ◽  
Wave Action ◽  
Ann Model ◽  
Climate Conditions ◽  
Wave Flume ◽  
Physical Model Tests ◽  
Rubble Mound ◽  
The Stability ◽  
Rubble Mound Breakwaters

Breakwaters are coastal structures constructed to shelter a harbour basin from waves. There are two main types: rubble-mound breakwaters, consisting of various layers of stones or concrete pieces of different sizes (weights), making up a porous mound; and vertical breakwaters, impermeable and monolythic, habitually composed of concrete caissons. This article deals with rubble-mound breakwaters. A typical rubble-mound breakwater consists of an armour layer, a filter layer and a core. For the breakwater to be stable, the armour layer units (stones or concrete pieces) must not be removed by wave action. Stability is basically achieved by weight. Certain types of concrete pieces are capable of achieving a high degree of interlocking, which contributes to stability by impeding the removal of a single unit. The forces that an armour unit must withstand under wave action depend on the hydrodynamics on the breakwater slope, which are extremely complex due to wave breaking and the porous nature of the structure. A detailed description of the flow has not been achieved until now, and it is unclear whether it will be in the future in view of the turbulent phenomena involved. Therefore the instantaneous force exerted on an armour unit is not, at least for the time being, amenable to determination by means of a numerical model of the flow. For this reason, empirical formulations are used in rubble-mound design, calibrated on the basis of laboratory tests of model structures. However, these formulations cannot take into account all the aspects affecting the stability, mainly because the inherent complexity of the problem does not lend itself to a simple treatment. Consequently the empirical formulations are used as a predesign tool, and physical model tests in a wave flume of the particular design in question under the pertinent sea climate conditions are de rigueur, except for minor structures. The physical model tests naturally integrate all the complexity of the problem. Their drawback lies in that they are expensive and time consuming. In this article, Artificial Neural Networks are trained and tested with the results of stability tests carried out on a model breakwater. They are shown to reproduce very closely the behaviour of the physical model in the wave flume. Thus an ANN model, if trained and tested with sufficient data, may be used in lieu of the physical model tests. A virtual laboratory of this kind will save time and money with respect to the conventional procedure.

Oblique wave attack on rubble mound breakwaters

2014 ◽  
Vol 88 ◽  
pp. 43-54 ◽  
Author(s):  
Marcel R.A. van Gent
Keyword(s):  
Oblique Wave ◽  
Rubble Mound ◽  
Rubble Mound Breakwaters

scholarly journals STABILITY OF ARMOR UNITS IN FLOW THROUGH A LAYER

1984 ◽  
Vol 1 (19) ◽  
pp. 175
Author(s):  
Alex C. Thompson ◽  
Hans F. Burcharth
Keyword(s):  
Steady Flow ◽  
Scale Effect ◽  
Oscillating Flow ◽  
Flow Angle ◽  
Reservoir Effect ◽  
Flow Through ◽  
Rubble Mound ◽  
Steep Waves ◽  
The Stability ◽  
Rubble Mound Breakwaters

As part of a program to study the hydraulics of wave attack on rubble mound breakwaters tests were made on model armour units in a steady flow through a layer laid on a slope. The flow angle has little effect on stability for dolosse or rock layers. The head drop at failure across each type of layer is similar but the dolosse layer is more permeable and fails as a whole. There was no viscous scale effect. These results and earlier tests in oscillating flow suggest a 'reservoir' effect is important in the stability in steep waves.

scholarly journals THE EFFECT OF TWIT WEIGHTS OF ROCK AND FLUID ON THE STABILITY OF RUBBLE MOUND BREAKWATERS

1966 ◽  
Vol 1 (10) ◽  
pp. 57 ◽  
Author(s):  
Anton Brandtzaeg
Keyword(s):  
Model Tests ◽  
Design Formula ◽  
Variable Quantity ◽  
Current Design ◽  
Rubble Mound ◽  
The Stability ◽  
Rubble Mound Breakwaters

To study the effect of the specific weights of armour block material and fluid on the stability of rubble mound breakwaters a total of 110 model tests were made, with varying specific weights of armour and fluid, sizes of blocks and slopes of the breakwater face. The tests indicate that in cases where the specific weights deviate much from usual values, the current design formula (Eq. (1)) should be modified by entering a variable quantity,

Wave RUN-UP Measurements under very oblique wave incidence

2021 ◽  
Vol 42 (1) ◽  
pp. 81-90
Author(s):  
Rute Lemos ◽  
Vera Pina ◽  
João Alfredo Santos ◽  
Conceição Fortes ◽  
Maria Teresa Reis ◽  
...  
Keyword(s):  
Physical Modelling ◽  
Stability Studies ◽  
Extreme Wave ◽  
Wave Basin ◽  
Rubble Mound ◽  
Run Up ◽  
Access Project ◽  
Multidirectional Wave ◽  
Rubble Mound Breakwaters ◽  
Wave Incidence

Under the scope of the HYDRALAB+ transnational access project, the so-called RODBreak experiment was conducted in the multidirectional wave basin at the Marienwerden facilities of the Leibniz University Hannover (LUH). A stretch of a rubble-mound breakwater was built in the wave basin with a very gentle slope. Its armour layer was made of Antifer cubes, at the roundhead and adjoining trunk, and of rock, at the rest of the trunk. A set of tests was carried out to extend the range of wave steepness values analysed in wave run-up, overtopping and armour layer stability studies, focusing on oblique extreme wave conditions, with incident wave angles from 40º to 90º. The present study focuses on the analysis of measured wave run-up values obtained in the tests and on their on their variability as well as the influence of the wave obliquity and directional spreading. Keywords: rubble-mound breakwaters; run-up; oblique waves; physical modelling; RODbreak.

Sign in / Sign up

Export Citation Format

Share Document