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.

scholarly journals THE ECONOMIC VALUE OP A NEW BREAKWATER ARMOUR UNIT 'DOLOS'

1966 ◽  
Vol 1 (10) ◽  
pp. 50 ◽  
Author(s):  
E.M. Merrifield ◽  
J.A. Zwamborn
Keyword(s):  
Economic Value ◽  
Full Scale ◽  
Field Conditions ◽  
Test Results ◽  
Shore Protection ◽  
Wave Channel ◽  
New Type ◽  
Rubble Mound ◽  
The Stability ◽  
Made In

The Dolos, a new type of armour unit which closely resembles a normal ship's anchor, was developed and tried out under field conditions on the main breakwater of East London harbour. Since these full-scale Dolosse proved very successful, tests were made in a wave channel to compare the stability of Dolosse with other known types of armour blocks. The test results showed that the Dolos is outstandingly stable, and since manufacture and random placing of Dolosse offers no particular difficulties it is concluded that in many cases the use of Dolosse in armour layers may lead to more economical solutions for rubble mound breakwater and shore protection works.

scholarly journals THE STABILITY OF RUBBLE MOUND BREAKWATERS AGAINST IRREGULAR WAVES

1966 ◽  
Vol 1 (10) ◽  
pp. 54 ◽  
Author(s):  
Torkild Carstens ◽  
Alf Torum ◽  
Anton Tratteberg
Keyword(s):  
Wave Spectrum ◽  
Model Tests ◽  
Irregular Waves ◽  
Regular Waves ◽  
Destructive Effect ◽  
Wave Channel ◽  
Stability Data ◽  
Rubble Mound ◽  
The Stability ◽  
Rubble Mound Breakwaters

Through extensive model tests with rubble mound breakwaters conducted in many laboratories in recent years design criteria and stability data have been collected. To our knowledge such data have been based on tests with regular waves only. It has been more or less accepted that the destructive effect of a train of regular waves corresponds to a confused sea with a significant wave height equal to the height of the regular waves. At the Rxver and Harbour Research Laboratory at the Technical University of Norway a new wave channel has been equipped with a programmed wave generator which can produce irregular waves wxth any wanted wave spectrum. This paper deals with model tests of the stability of rubble mound breakwaters against irregular waves as compared with regular waves.

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.

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.

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,

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 Assessment of Rubble Mound Breakwaters Using Extreme Learning Machine Models

2019 ◽  
Vol 7 (9) ◽  
pp. 312 ◽  
Author(s):  
Xianglong Wei ◽  
Huaixiang Liu ◽  
Xiaojian She ◽  
Yongjun Lu ◽  
Xingnian Liu ◽  
...  
Keyword(s):  
Extreme Learning Machine ◽  
Data Driven ◽  
Stability Assessment ◽  
Training Samples ◽  
Machine Learning Approach ◽  
Rubble Mound ◽  
Learning Machine ◽  
The Stability ◽  
Rubble Mound Breakwaters ◽  
User Intervention

The stability number of a breakwater can determine the armor unit’s weight, which is an important parameter in the breakwater design process. In this paper, a novel and simple machine learning approach is proposed to evaluate the stability of rubble-mound breakwaters by using Extreme Learning Machine (ELM) models. The data-driven stability assessment models were built based on a small size of training samples with a simple establishment procedure. By comparing them with other approaches, the simulation results showed that the proposed models had good assessment performances. The least user intervention and the good generalization ability could be seen as the advantages of using the stability assessment models.

scholarly journals AKMON ARMOUR UNIT FOR COVER LAYERS OF RUBBLE MOUND BREAKWATERS

2011 ◽  
Vol 1 (8) ◽  
pp. 25
Author(s):  
A. Paape ◽  
A.W. Walther
Keyword(s):  
Laboratory Tests ◽  
Design Procedure ◽  
Concrete Block ◽  
Block Type ◽  
Protective Cover ◽  
Rubble Mound ◽  
The Stability ◽  
Rubble Mound Breakwaters

A new specially shaped concrete block, the "Akmon", to be used as armour unit for protective cover layers of rubble mound breakwaters is presented. The characteristics as have been derived from laboratory tests are compared with those of various other types of blocks. Some considerations are given on the design procedure for cover layers, as it appears that this procedure has an influence on the block-type and -weight to be chosen. If armour units have to be placed at random, which is in many oases an imperative necessity, the akmon appears to be one of the most suitable blocks developed up till now. For two different breakwaters, the results are given of model investigations concerning the stability under the attack of waves generated by a wave board and wind.

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