EP0381572A1 - Device for attenuating sea swell - Google Patents
Device for attenuating sea swell Download PDFInfo
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- EP0381572A1 EP0381572A1 EP90400246A EP90400246A EP0381572A1 EP 0381572 A1 EP0381572 A1 EP 0381572A1 EP 90400246 A EP90400246 A EP 90400246A EP 90400246 A EP90400246 A EP 90400246A EP 0381572 A1 EP0381572 A1 EP 0381572A1
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- upstream edge
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- 238000011144 upstream manufacturing Methods 0.000 claims abstract description 51
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 31
- 230000000644 propagated effect Effects 0.000 abstract 1
- 230000005540 biological transmission Effects 0.000 description 6
- 230000000694 effects Effects 0.000 description 4
- 230000002238 attenuated effect Effects 0.000 description 3
- 238000004364 calculation method Methods 0.000 description 3
- 238000007654 immersion Methods 0.000 description 3
- 230000010363 phase shift Effects 0.000 description 3
- 230000005284 excitation Effects 0.000 description 2
- 238000013178 mathematical model Methods 0.000 description 2
- 241000282836 Camelus dromedarius Species 0.000 description 1
- 241000251730 Chondrichthyes Species 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000006073 displacement reaction Methods 0.000 description 1
- 230000010355 oscillation Effects 0.000 description 1
- 230000003534 oscillatory effect Effects 0.000 description 1
- 230000001902 propagating effect Effects 0.000 description 1
- 230000003313 weakening effect Effects 0.000 description 1
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02B—HYDRAULIC ENGINEERING
- E02B3/00—Engineering works in connection with control or use of streams, rivers, coasts, or other marine sites; Sealings or joints for engineering works in general
- E02B3/04—Structures or apparatus for, or methods of, protecting banks, coasts, or harbours
- E02B3/06—Moles; Piers; Quays; Quay walls; Groynes; Breakwaters ; Wave dissipating walls; Quay equipment
Definitions
- a wave attenuating device designed to cause the formation of a "fixed wall of water" which creates, upstream of the device, a reflected wave consisting of the incident wave to give rise to a lapping, so that the transmitted wave, downstream of the device, is zero or attenuated.
- This device comprises a fixed horizontal plate slightly immersed in the incident swell, the upstream and downstream edges of which are turned upwards up to a positive dimension above the free surface of the water, so that the incident swell does not can spread freely over the plate.
- the mass of water trapped between the fixed horizontal plate and the natural bottom can therefore only have horizontal displacements, and behaves globally, notwithstanding its own internal oscillation, like a homogeneous inertial obstacle vis-à-vis the incident swell , the latter being reflected on this "fixed water wall" and this all the better as its energy (or period) is lower.
- the reflection of the incident wave on the "fixed water wall” thus formed generates a reflected wave which creates, in the vicinity of the upstream edge of the device, the aforementioned lapping whose amplitude is close to twice the amplitude of the incident swell.
- this lapping becomes sufficiently energetic to cause an overall excitation of the mass of water which constitutes the "fixed wall of water", capable of giving it a global oscillatory movement likely to appear, downstream of the device, a transmitted wave of insufficiently reduced amplitude.
- the purpose of this addition is to improve the device of the main patent so as to allow the attenuation of the harmful energetic effect of the lapping which is created in the vicinity of the upstream edge of the plate.
- Improvement consists in providing, in the upstream edge of the plate, a recess which reduces the width of the latter above a miter-shaped part. remaining at its lower face, so that the upstream edge breaks down into a primary upstream edge constituted by the front edge of said tab and a secondary upstream edge, set back from a determined distance from the primary upstream edge, this distance being chosen so as to reduce or cancel the amplitude of the lapping resulting from the combination of the swell components in line with the primary upstream edge, namely the incident component and the components due to the presence of the device.
- the present addition therefore relates to the implementation of a submerged tab which is fixed to the front of the plate, in the extension of the underside thereof, and whose dimensions are such that the amplitude of the resulting swell in the vicinity of the upstream edge of the tab is small, or even zero, so that the mass of water in the "fixed water wall" trapped between the plate extended by the tab and the bottom of the sea is no longer subjected to a significant excitation alternating force and that consequently the wave transmitted beyond the downstream edge of the plate is much weaker than the wave transmitted without the presence of said tab.
- the ratio of the thickness of the tab to the depth of water where the plate is installed is preferably between 1/30 and 1/50.
- the secondary anterior edge created by the presence of the recess can constitute a front either substantially planar and vertical, or, to soften the impact effects of the swell, inclined downstream, connecting to the tab by a fillet .
- Figure 1 first recalls the basic configuration of the device according to the main patent, implementing the phenomenon of "fixed water wall", in which a fixed horizontal plate 1, offering its upstream edges 1a and downstream 1b raised towards the top, constitutes a fixed box mounted on rigid piles 2 anchored on the bottom 3 of the sea, below which is formed, between its horizontal lower face 1c and the bottom 3, said fixed water wall 4 which behaves overall as an inertial obstacle vis-à-vis the ocean swell.
- the plate 1, of width W is partially submerged over a depth i, its upstream edges 1a and downstream 1b emerging from the free surface 5 of the sea so as to prevent the propagation of the waves over the device.
- the latter extends, transverse to the direction of the swell to be attenuated, over a significant length which depends on the nature and configuration of the site to be protected.
- An incident wave wave Fi of amplitude 2d hollow head, is reflected on the upstream edge 1a of the box according to a reflected wave Fr.
- l incident wave Fi is almost completely reflected on the obstacle constituted by the body of water 4 trapped between this underside and the bottom 3 of the sea to give rise, upstream of the device, to a standing wave Fi + Fr forming a lapping amplitude 4d hollow head, while the transmitted wave Ft is attenuated.
- Figure 2 shows how is modified, according to this addition, the device of Figure 1.
- a recess 6 of width a is formed at the front of the plate 1, extending over almost its entire thickness h so not to affect the lower face 1c which remains unchanged. Only a tab 7 of thin thickness e remains, which ends with the residual lower portion 1′a of the original upstream edge 1a (primary upstream edge), the rest of this upstream edge being set back by the width a of the recess 6 to form a secondary upstream edge 1 ⁇ a.
- the width of the plate 1 thus modified equal to the sum of width a of the tab 7 and the width b of the part of the plate not reached by the recess 6, is equal to the width W of the plate 1 of origin.
- This wave F1 propagates along the tab before reaching the secondary upstream edge 1 ⁇ a of the plate, where it takes a value F2 which is deduced from F1 by a phase shift e -j ⁇ :
- FIGS. 3 to 5 illustrate the advantages of the device according to the addition:
- C T Ft / Fi as a function of the period T of the incident swell.
- FIGS. 3 to 5 illustrate the variations of the coefficient C T d swell attenuation:
- C T Ft / Fi as a function of the period T of the incident swell.
- the scale model used was produced at a scale of 1/65.
- the improvement according to the addition effectively provides an attenuation of the harmful energetic effect of the lapping which is created in the vicinity of the upstream edge of the plate with upstream and downstream edges raised when the latter creates a wall of fixed water on which the incident swell is reflected.
- This attenuation becomes appreciable when the period of the incident swell is sufficiently long, that is to say precisely when the lapping would become sufficiently energetic to cause an increase in the transmission coefficient if the configuration with tab object of the addition was not not implemented.
- the thickness e of the tab it has been found that it should be chosen between 1 / 30th and 1 / 50th of the water depth H.
- an upwardly open cavity can advantageously be provided in the plate between its upstream and downstream edges.
- FIG. 6 The precise profile of a wave attenuation plate comprising this latter arrangement is represented in FIG. 6.
- This profile is symmetrical, that is to say that a downstream tab 8, of the same shape as the tab upstream 7, is associated with the downstream edge 1b of the plate.
- the latter is pierced with a series of orifices 10 (FIG. 7) allowing the flow of water accumulated in the central cavity 11 provided between the upstream recessed edges 1a and downstream 1b.
- the profile of Figure 6 has upstream and downstream edges rounded "camel back". To reduce the effects of slapping inflicted by the swell on the upstream edge thus shaped, because of its steep slope, it may be useful to modify its content to give it the shape of a "shark fin” (indicated in dashes) ), its face turned upstream then being more enveloping vis-à-vis a swell with breaking tendency propagating above the tab 7.
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Abstract
Description
Dans le brevet principal a été proposé un dispositif atténuateur de houle conçu pour causer la formation d'un " mur d'eau fixe" qui crée, en amont du dispositif, une onde réfléchie se composant avec l'onde incidente pour donner naissance à un clapotis, de sorte que l'onde transmise, en aval du dispositif, est nulle ou atténuée.In the main patent, a wave attenuating device has been proposed, designed to cause the formation of a "fixed wall of water" which creates, upstream of the device, a reflected wave consisting of the incident wave to give rise to a lapping, so that the transmitted wave, downstream of the device, is zero or attenuated.
Ce dispositif comporte une plaque horizontale fixe faiblement immergée dans la houle incidente, dont les bords amont et aval sont retournés vers le haut jusqu'à une cote positive au-dessus de la surface libre de l'eau, de sorte que la houle incidente ne puisse se propager librement au-dessus de la plaque. La masse d'eau emprissonnée entre la plaque horizontale fixe et le fond naturel ne peut dès lors avoir que des déplacements horizontaux, et se comporte globalement, nonobstant une oscillation interne propre, comme un obstacle inertiel homogène vis-à-vis de la houle incidente, celle-ci étant réfléchie sur ce "mur d'eau fixe" et ce d'autant mieux que son énergie (ou période) est plus faible.This device comprises a fixed horizontal plate slightly immersed in the incident swell, the upstream and downstream edges of which are turned upwards up to a positive dimension above the free surface of the water, so that the incident swell does not can spread freely over the plate. The mass of water trapped between the fixed horizontal plate and the natural bottom can therefore only have horizontal displacements, and behaves globally, notwithstanding its own internal oscillation, like a homogeneous inertial obstacle vis-à-vis the incident swell , the latter being reflected on this "fixed water wall" and this all the better as its energy (or period) is lower.
Cependant, la réflexion de l'onde incidente sur le "mur d'eau fixe" ainsi constitué engendre une onde réfléchie qui crée, au voisinage du bord amont du dispositif, le clapotis précité dont l'amplitude est proche du double de l'amplitude de la houle incidente. Lorsque la période, donc l'énergie de la houle augmente, ce clapotis devient suffisamment énergétique pour causer une excitation d'ensemble de la masse d'eau qui constitue le "mur d'eau fixe", capable de lui conférer un mouvement oscillatoire global susceptible de faire apparaître, en aval du dispositif, une onde transmise d'amplitude insuffisamment réduite.However, the reflection of the incident wave on the "fixed water wall" thus formed generates a reflected wave which creates, in the vicinity of the upstream edge of the device, the aforementioned lapping whose amplitude is close to twice the amplitude of the incident swell. When the period, therefore the energy of the swell increases, this lapping becomes sufficiently energetic to cause an overall excitation of the mass of water which constitutes the "fixed wall of water", capable of giving it a global oscillatory movement likely to appear, downstream of the device, a transmitted wave of insufficiently reduced amplitude.
La présente addition a pour but d'améliorer le dispositif du brevet principal de façon à permettre l'atténuation de l'effet énergétique néfaste du clapotis qui se crée au voisinage du bord amont de la plaque.The purpose of this addition is to improve the device of the main patent so as to allow the attenuation of the harmful energetic effect of the lapping which is created in the vicinity of the upstream edge of the plate.
Le perfectionnement selon l'addition consiste à prévoir, dans le bord amont de la plaque, un évidement qui diminue la largeur de celle-ci au-dessus d'une partie en forme d'onglet subsistant au niveau de sa face inférieure, de sorte que le bord amont se décompose en un bord amont primaire constitué par le bord antérieur dudit onglet et un bord amont secondaire, en retrait d'une distance déterminée par rapport au bord amont primaire, cette distance étant choisie de façon à réduire ou à annuler l'amplitude du clapotis résultant de la combinaison des composantes de houle au droit du bord amont primaire, savoir la composante incidente et les composantes dues à la présence du dispositif. Ces dernières comprennent la composante réfléchie par le bord amont primaire, la composante induite par la houle incidente à l'entrée du volume d'eau surmontant l'onglet et correspondant audit évidement, et la composante issue de ladite composante induite après réflexion sur le bord amont secondaire et déphasage en raison du trajet aller et retour accompli à travers ce volume d'eau.Improvement according to the addition consists in providing, in the upstream edge of the plate, a recess which reduces the width of the latter above a miter-shaped part. remaining at its lower face, so that the upstream edge breaks down into a primary upstream edge constituted by the front edge of said tab and a secondary upstream edge, set back from a determined distance from the primary upstream edge, this distance being chosen so as to reduce or cancel the amplitude of the lapping resulting from the combination of the swell components in line with the primary upstream edge, namely the incident component and the components due to the presence of the device. These include the component reflected by the primary upstream edge, the component induced by the incident swell at the entry of the volume of water surmounting the tab and corresponding to said recess, and the component resulting from said component induced after reflection on the edge. secondary upstream and phase shift due to the outward and return journey accomplished through this volume of water.
La présente addition a donc pour objet la mise en oeuvre d'un onglet immergé qui vient se fixer à l'avant de la plaque, dans le prolongement de la face inférieure de celle-ci, et dont les dimensions sont telles que l'amplitude de la houle résultante au voisinage du bord amont de l'onglet soit faible, voire nulle, de sorte que la masse d'eau du "mur d'eau fixe" emprisonnée entre la plaque prolongée par l'onglet et le fond de la mer ne soit plus soumise à une force alternative excitatrice importante et qu'en conséquence l'onde transmise au-delà du bord aval de la plaque soit beaucoup plus faible que l'onde transmise sans la présence dudit onglet.The present addition therefore relates to the implementation of a submerged tab which is fixed to the front of the plate, in the extension of the underside thereof, and whose dimensions are such that the amplitude of the resulting swell in the vicinity of the upstream edge of the tab is small, or even zero, so that the mass of water in the "fixed water wall" trapped between the plate extended by the tab and the bottom of the sea is no longer subjected to a significant excitation alternating force and that consequently the wave transmitted beyond the downstream edge of the plate is much weaker than the wave transmitted without the presence of said tab.
On a constaté qu'il convenait de donner à la distance de retrait précitée, c'est-à-dire à la largeur de l'onglet, une valeur voisine du 1/10e de la longueur d'onde maximale de la houle dont on souhaite arrêter la propagation. D'autre part, le rapport de l'épaisseur de l'onglet à la profondeur d'eau à l'endroit où est installée la plaque est de préférence compris entre 1/30 et 1/50.It was found that it was advisable to give the abovementioned withdrawal distance, that is to say the width of the tab, a value close to 1 / 10th of the maximum wavelength of the swell which is wish to stop the spread. On the other hand, the ratio of the thickness of the tab to the depth of water where the plate is installed is preferably between 1/30 and 1/50.
Le bord antérieur secondaire créé par la présence de l'évidement peut constituer un front soit sensiblement plan et vertical, soit, pour adoucir les effets d'impact de la houle, incliné vers l'aval, se raccordant à l'onglet par un congé.The secondary anterior edge created by the presence of the recess can constitute a front either substantially planar and vertical, or, to soften the impact effects of the swell, inclined downstream, connecting to the tab by a fillet .
D'autres particularités et avantages du perfectionnement selon l'addition ressortiront de la description qui va suivre, en regard des dessins annexés, d'exemples de réalisation non limitatifs.
- La figure 1 représente, en coupe transversale par un plan vertical, un dispositif d'atténuation de la houle selon le brevet principal.
- La figure 2 représente, à la manière de la figure 1, un dispositif perfectionné selon la présente addition.
- Les figures 3 à 5 donnent, sous forme de graphiques, les valeurs du coefficient d'atténuation de la houle en fonction de la période de celle-ci, respectivement pour un dispositif selon la figure 1 et pour deux dispositifs selon la figure 2.
- La figure 6 représente, à l'échelle, un dispositif selon l'addition dans une variante de réalisation.
- La figure 7 représente une partie de l'objet de la figure 6 vu suivant la flèche VII.
- La figure 8 donne, à la manière des figures 3 à 5, les résultats obtenus avec le dispositif de la figure 6.
- Figure 1 shows, in cross section through a vertical plane, a wave attenuation device according to the main patent.
- FIG. 2 represents, in the manner of FIG. 1, an improved device according to the present addition.
- Figures 3 to 5 give, in the form of graphs, the values of the wave attenuation coefficient as a function of the period of the latter, respectively for a device according to Figure 1 and for two devices according to Figure 2.
- Figure 6 shows, to scale, a device according to the addition in an alternative embodiment.
- FIG. 7 represents a part of the object of FIG. 6 seen according to arrow VII.
- FIG. 8 gives, in the manner of FIGS. 3 to 5, the results obtained with the device of FIG. 6.
La figure 1 rappelle tout d'abord de configuration fondamentale du dispositif selon le brevet principal, mettant en oeuvre le phénomène de "mur d'eau fixe", dans laquelle une plaque horizontale fixe 1, offrant ses bords amont 1a et aval 1b relevés vers le haut, constitue un caisson fixe monté sur des pilotis rigides 2 ancrés sur le fond 3 de la mer, au-dessous duquel se forme, entre sa face inférieure horizontale 1c et le fond 3, ledit mur d'eau fixe 4 qui se comporte globalement comme un obstacle inertiel vis-à-vis de la houle du large. La plaque 1, de largeur W, est partiellement immergée sur une profondeur i, ses bords amont 1a et aval 1b émergeant de la surface libre 5 de la mer de façon à empêcher la propagation des vagues par-dessus le dispositif. Ce dernier s'étend, transversalement à la direction de la houle à atténuer, sur une longueur importante qui dépend de la nature et de la configuration du site à protéger.Figure 1 first recalls the basic configuration of the device according to the main patent, implementing the phenomenon of "fixed water wall", in which a fixed horizontal plate 1, offering its
Une onde de houle incidente Fi, d'amplitude 2d tête à creux, se réfléchit sur le bord amont 1a du caisson suivant une onde réfléchie Fr. Lorsque le "mur d'eau fixe" fonctionne parfaitement sous la face inférieure 1c du caisson, l'onde incidente Fi se réfléchit quasi totalement sur l'obstacle constitué par la masse d'eau 4 emprisonée entre cette face inférieure et le fond 3 de la mer pour donner naissance, en amont du dispositif, à une onde stationnaire Fi + Fr formant un clapotis d'amplitude 4d tête à creux, tandis que l'onde transmise Ft est atténuée.An incident wave wave Fi, of
Cependant, lorsque l'énergie de l'onde incidente Fi augmente, c'est-à-dire lorsque la période de cette onde croît, l'énergie du clapotis en amont du mur d'eau fixe 4 devient suffisante pour exciter harmoniquement l'ensemble de la masse d'eau qui le constitue, de sorte que l'onde transmise Ft devient plus importante, et cela d'autant plus que la période (donc l'énergie) de la houle incidente a augmenté.However, when the energy of the incident wave Fi increases, that is to say when the period of this wave increases, the energy of the lapping upstream of the
La figure 2 montre comment est modifié, selon la présente addition, le dispositif de la figure 1. Un évidement 6 de largeur a est pratiqué à l'avant de la plaque 1, s'étendant sur la presque totalité de son épaisseur h de façon à ne pas affecter la face inférieure 1c qui reste inchangée. Seul subsiste un onglet 7 de faible épaisseur e, qui se termine par la portion inférieure résiduelle 1′a du bord amont d'origine 1a (bord amont primaire), le reste de ce bord amont se trouvant reculé de la largeur a de l'évidement 6 pour former un bord amont secondaire 1˝a. La largeur de la plaque 1 ainsi modifiée, égale à la somme de largeur a de l'onglet 7 et de la largeur b de la partie de la plaque non atteinte par l'évidement 6, est égale à la largeur W de la plaque 1 d'origine. Une onde de houle incidente Fi d'amplitude 2d, arrivant sur le dispositif de la figure 2, donne naissance à une onde réfléchie Fr au droit du bord amont 1′a de l'onglet 7, tandis qu'une onde F1 est engendrée dans le volume d'eau compris entre la face supérieure de l'onglet 7 et la surface libre, correspondant à l'évidement 6. Cette onde F1 se propage le long de l'onglet avant d'atteindre le bord amont secondaire 1˝a de la plaque, où elle prend une valeur F2 qui se déduit de F1 par un déphasage e-jφ :
F2 = F1 e-jφ, où φ = 2 π a/λ,
λ étant la longueur d'onde de l'onde F1, qui est directement liée à la profondeur d'immersion i de l'onglet 7.Figure 2 shows how is modified, according to this addition, the device of Figure 1. A
F2 = F1 e -jφ , where φ = 2 π a / λ,
λ being the wavelength of the wave F1, which is directly linked to the immersion depth i of
Cette onde se réfléchit entièrement sur le bord amont secondaire 1˝a de la plaque suivant une onde f2 égale, qui se propage à son tour en sens inverse le long de l'onglet avant d'atteindre le bord amont 1′a de celui-ci où elle a alors une valeur f1 déduite de f2 par le déphasage e-jφ (avec toujours φ = 2πa/λ) :
f1 = f2 e-jφ.This wave is fully reflected on the secondary upstream edge 1˝a of the plate in an equal wave f2, which in turn propagates in the opposite direction along the tab before reaching the upstream edge 1′a thereof. ci where it then has a value f1 deduced from f2 by the phase shift e -jφ (with always φ = 2πa / λ):
f1 = f2 e -jφ .
Ainsi, au droit du bord amont 1′a de l'onglet se superposent quatre ondes :
- l'onde incidente Fi
- l'onde réfléchie Fr
- l'onde F1 induite dans le volume 6 surmontant l'onglet 7
- l'onde réfléchie f1 au sein de ce volume.Thus, to the right of the upstream edge 1′a of the tab, four waves are superimposed:
- the incident wave Fi
- the reflected wave Fr
- the F1 wave induced in
- the reflected wave f1 within this volume.
Il est alors possible de dimensionner la profondeur d'immersion i de l'onglet 7 et sa longueur a pour que la superposition de ces quatre ondes Fi + Fr + F1 + f1 donne une résultante de clapotis minimale à proximité du bord amont primaire 1′a, c'est-à-dire à l'extrémité antérieure de la face inférieure 1c de la plaque 1.It is then possible to size the immersion depth i of
Dans ces conditions, le mur d'eau fixe 4, qui règne sur la longueur W = a + b et concerne le volume d'eau compris entre d'une part la face inférieure de l'onglet et de la portion résiduelle du caisson 1 et d'autre part le fond 3 de la mer, n'est plus excité par un clapotis éventuellement excessif, mais par une onde résultante que l'on peut rendre énergétiquement minimale, voire nulle, dans une gamme de périodes de houle donnée. On constate en conséquence que l'onde transmise Ft en aval du dispositif de la figure 2, comportant un onglet 7 adapté de façon optimale, est beaucoup plus faible que l'onde transmise Ft dans le cas où cet onglet n'est pas mis en oeuvre (figure 1).Under these conditions, the
Les avantages du dispositif selon l'addition (figure 2) ont été confirmés par calcul sur modèle mathématique et par expérimentation sur modèle réduit, ainsi qu'on peut le voir sur les figures 3 à 5, qui illustrent les variations du coefficient CT d'atténuation de la houle :
CT = Ft / Fi
en fonction de la période T de la houle incidente. Ces figures sont relatives respectivement à des dispositifs selon les figures 1 et 2 de même largeur totale W = 40 m et de même profondeur d'immersion i = 10 m, installés dans une mer de profondeur H = 50 m. La figure 3 se rapporte au dispositif de la figure 1 et les figures 4 et 5 à celui de la figure 2 avec un onglet de largeur a = 8 m et a = 16 m, respectivement. Le modèle réduit utilisé était réalisé à l'échelle de 1/65.The advantages of the device according to the addition (FIG. 2) were confirmed by calculation on a mathematical model and by experimentation on a reduced model, as can be seen in FIGS. 3 to 5, which illustrate the variations of the coefficient C T d swell attenuation:
C T = Ft / Fi
as a function of the period T of the incident swell. These figures relate respectively to devices according to Figures 1 and 2 of the same total width W = 40 m and the same immersion depth i = 10 m, installed in a sea of depth H = 50 m. Figure 3 relates to the device of Figure 1 and Figures 4 and 5 to that of Figure 2 with a tab width a = 8 m and a = 16 m, respectively. The scale model used was produced at a scale of 1/65.
Les résultats obtenus par calcul sur modèle mathématique sont exprimés sur les figures 3 à 5 sous forme de courbes continues et ceux obtenus par expérimentation sur modèle réduit par des points discrets. Ces figures permettent d'apprécier, outre la bonne corrélation entre les résultats du calcul mathématique et de l'expérimentation, l'amélioration obtenue sur le coefficient de transmission CT grâce à la présence de l'onglet 7.The results obtained by calculation on a mathematical model are expressed in FIGS. 3 to 5 in the form of continuous curves and those obtained by experimentation on a reduced model by discrete points. These figures make it possible to appreciate, in addition to the good correlation between the results of the mathematical calculation and of the experimentation, the improvement obtained on the transmission coefficient C T thanks to the presence of the
C'est ainsi par exemple que le coefficient de transmission mesuré qui, dans le cas du seul caisson parallélépipédique (figure 1) est de 0,4 environ par une houle de période de 10 secondes, est abaissé à 0,24 environ lorsqu'un onglet de 8 mètres de large (figure 2) est mis en oeuvre devant le caisson (de largeur b réduite à 32 mètres) et à 0,18 environ lorsqu'un onglet de 16 mètres de large (figure 3) est mis en oeuvre devant le caisson (de largeur b réduite à 24 mètres).Thus, for example, the measured transmission coefficient which, in the case of the single rectangular box (Figure 1) is approximately 0.4 per swell with a period of 10 seconds, is lowered to approximately 0.24 when a 8-meter wide tab (Figure 2) is used in front of the box (width b reduced to 32 meters) and approximately 0.18 when a 16-meter wide tab (Figure 3) is used in front the box (width b reduced to 24 meters).
La comparaison des courbes des figures 4 et 5 permet de se rendre compte de l'influence exercée par la longueur de l'onglet. On voit qu'une augmentation de la longueur de l'onglet (de 8 mètres à 16 mètres), si elle se traduit par une croissance du coefficient de transmission pour des houles de périodes moyennes (entre 4 et 10 secondes environ) se traduit surtout par un abaissement sensible de ce coefficient de transmission pour des houles de grandes périodes (supérieures à 10 secondes).The comparison of the curves of FIGS. 4 and 5 makes it possible to realize the influence exerted by the length of the tab. We see that an increase in the length of the tab (from 8 meters to 16 meters), if it results in a growth in the transmission coefficient for swells of average periods (between 4 and 10 seconds approximately) results above all in a significant reduction in this transmission coefficient for swells of long periods (greater than 10 seconds).
Ainsi, il apparaît clairement que le perfectionnement selon l'addition procure effectivement une atténuation de l'effet énergétique néfaste du clapotis qui se crée au voisinage du bord amont de la plaque avec bords amont et aval relevés lorsque celle-ci crée un mur d'eau fixe sur lequel vient se réfléchir la houle incidente. Cette atténuation devient sensible lorsque la période de la houle incidente est suffisamment importante, c'est-à-dire précisément lorsque le clapotis deviendrait suffisamment énergétique pour causer une augmentation du coefficient de transmission si la configuration à onglet objet de l'addition n'était pas mise en oeuvre.Thus, it clearly appears that the improvement according to the addition effectively provides an attenuation of the harmful energetic effect of the lapping which is created in the vicinity of the upstream edge of the plate with upstream and downstream edges raised when the latter creates a wall of fixed water on which the incident swell is reflected. This attenuation becomes appreciable when the period of the incident swell is sufficiently long, that is to say precisely when the lapping would become sufficiently energetic to cause an increase in the transmission coefficient if the configuration with tab object of the addition was not not implemented.
Les essais pratiqués sur des plaques de configurations différentes ont montré que, pour obtenir un affaiblissement suffisant de la houle (c'est-à-dire un coefficient d'atténuation CT < 0,2) par une profondeur d'eau H de 50 m, des largeurs d'onglet a de 8 m, 10 m et 12 m convenaient respectivement pour des houles de période maximale de 7 s, 8 s et 9 s, soit, pour la prodondeur indiquée, de longueur d'onde maximale d'environ 76 m, 100 m et 125 m. Il apparaît donc que la largeur optimale de l'onglet est de l'ordre du dixième de la longueur d'onde maximale de houle à arrêter pour la profondeur d'eau considérée.The tests carried out on plates of different configurations have shown that, to obtain a sufficient weakening of the swell (that is to say a coefficient of attenuation C T <0.2) by a water depth H of 50 m, miter widths a of 8 m, 10 m and 12 m were suitable respectively for swells with a maximum period of 7 s, 8 s and 9 s, i.e., for the depth indicated, with a maximum wavelength of about 76 m, 100 m and 125 m. It therefore appears that the optimal width of the tab is of the order of a tenth of the maximum wave length of the swell to be stopped for the depth of water considered.
Quant à l'épaisseur e de l'onglet, on a constaté qu'il convenait de la choisir entre le 1/30e et le 1/50e de la profondeur d'eau H.As for the thickness e of the tab, it has been found that it should be chosen between 1 / 30th and 1 / 50th of the water depth H.
Comme il a déjà été indiqué dans le brevet principal, une cavité ouverte vers le haut peut être avantageusement prévue dans la plaque entre ses bords amont et aval. Ainsi, lorsque la houle est assez forte pour franchir le bord amont, elle perd une bonne part de son énergie en retombant sur le matelas d'eau que contient cette cavité, l'excès d'eau momentané dans celle-ci étant évacué par des orifices ménagés dans le bord aval.As already indicated in the main patent, an upwardly open cavity can advantageously be provided in the plate between its upstream and downstream edges. Thus, when the swell is strong enough to cross the upstream edge, it loses a good part of its energy by falling back on the mattress of water which this cavity contains, the excess momentary water in it being evacuated by holes in the downstream edge.
Le profil précis d'une plaque d'atténuation de la houle comportant cette dernière disposition est représenté à la figure 6. Ce profil est symétrique, c'est-à-dire qu'un onglet aval 8, de même forme que l'onglet amont 7, est associé au bord aval 1b de la plaque. Ce dernier est percé d'une série d'orifices 10 (figure 7) permettant l'écoulement de l'eau accumulée dans la cavité centrale 11 prévue entre les bords amont en retrait 1˝a et aval 1b.The precise profile of a wave attenuation plate comprising this latter arrangement is represented in FIG. 6. This profile is symmetrical, that is to say that a
Une plaque ayant le profil représenté à la figure 6, mais réduite au 1/20e, a été soumise à une expérimentation en canal à houle où ont été mesurées les valeurs du coefficient de transmission CT pour des houles de différentes périodes. Les résultats obtenus, affectés d'un coefficient de similitude afin de correspondre à une plaque de 40 m de large, soit de largeur égale à celle des plaques auxquelles se rapportent les figures 3 à 5, sont reportés sur la figure 8. On observera qu'ils sont comparables (supérieurs pour les plus longues périodes) aux résultats montrés à la figure 4 pour une plaque ayant un onglet de 8 mètres.A plate having the profile shown in FIG. 6, but reduced to 1 / 20th, was subjected to an experiment in a swell channel where the values of the transmission coefficient C T were measured for swells of different periods. The results obtained, assigned a similarity coefficient in order to correspond to a
Le profil de la figure 6 comporte des bords amont et aval arrondis en "dos de chameau". Pour atténuer les effets de gifle infligés par la houle sur le bord amont ainsi conformé, du fait de sa pente trop accentuée, il peut être utile de modifier son contenu pour lui donner la forme d'une "aileron de requin" (indiqué en tirets), sa face tournée vers l'amont étant alors plus enveloppante vis-à-vis d'une houle à tendance déferlante se propageant au-dessus de l'onglet 7.The profile of Figure 6 has upstream and downstream edges rounded "camel back". To reduce the effects of slapping inflicted by the swell on the upstream edge thus shaped, because of its steep slope, it may be useful to modify its content to give it the shape of a "shark fin" (indicated in dashes) ), its face turned upstream then being more enveloping vis-à-vis a swell with breaking tendency propagating above the
Claims (5)
caractérisé par le fait que le bord amont (1a) de celle-ci comporte un évidement (6) qui diminue la largeur de la plaque (1) au-dessus d'une partie en forme d'onglet (7) subsistant au niveau de la face inférieure (1c) de la plaque, de sorte que le bord amont se décompose en un bord amont primaire (1′a) constitué par le bord antérieur dudit onglet et un bord amont secondaire (1˝a), en retrait d'une distance (a) déterminée par rapport un bord amont primaire (1′a), cette distance (a) étant choisie de façon à réduire ou à annuler l'amplitude du clapotis résultant de la combinaison des composantes de houle au droit du bord amont primaire, savoir la composante incidente (Fi) et les composantes (Fr, F1, f1) dues à la présence du dispositif.1. A device for attenuating swell at a given site, with a view in particular to protecting it, comprising, according to claim 2 of the main patent, a plate slightly immersed in the incident swell, said plate being kept fixed on rigid supports and its upstream and downstream edges being turned upwards to a positive dimension above the free surface of the water, so that the incident swell cannot propagate freely over the plate,
characterized in that the upstream edge (1a) thereof has a recess (6) which reduces the width of the plate (1) above a miter-shaped part (7) remaining at the level of the underside (1c) of the plate, so that the upstream edge breaks down into a primary upstream edge (1′a) constituted by the anterior edge of said tab and a secondary upstream edge (1˝a), set back from a distance (a) determined relative to a primary upstream edge (1′a), this distance (a) being chosen so as to reduce or cancel the amplitude of the lapping resulting from the combination of the swell components at the right of the upstream edge primary, namely the incident component (Fi) and the components (Fr, F1, f1) due to the presence of the device.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FR898901125A FR2642481B2 (en) | 1985-10-23 | 1989-01-30 | IMPROVED SWELL ATTENUATION DEVICE |
| FR8901125 | 1989-01-30 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| EP0381572A1 true EP0381572A1 (en) | 1990-08-08 |
| EP0381572B1 EP0381572B1 (en) | 1994-08-03 |
Family
ID=9378252
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP90400246A Expired - Lifetime EP0381572B1 (en) | 1989-01-30 | 1990-01-30 | Device for attenuating sea swell |
Country Status (5)
| Country | Link |
|---|---|
| EP (1) | EP0381572B1 (en) |
| ES (1) | ES2060971T3 (en) |
| IL (1) | IL93208A (en) |
| MA (1) | MA21740A1 (en) |
| TN (1) | TNSN90011A1 (en) |
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2671569A1 (en) * | 1991-01-15 | 1992-07-17 | Doris Engineering | Method for installing a device for protection against the swell, and device resulting from the implementation of this method |
| FR2673213A1 (en) * | 1991-02-21 | 1992-08-28 | Sogreah | Break-water |
| FR2693216A1 (en) * | 1992-07-03 | 1994-01-07 | Doris Engineering | Reinforced or prestressed concrete sea swell protection barrier - comprises several caissons anchored on tubular struts and rear whirlpool basins with water openings protecting wall and top slab deck |
| WO1998029610A1 (en) * | 1997-01-03 | 1998-07-09 | Bouygues Offshore | Improvements to fixed partially immersed caisson dikes |
| FR2758147A1 (en) * | 1997-01-03 | 1998-07-10 | Bouygues Offshore | Semi=submerged caisson=type breakwater |
| FR2877022A1 (en) | 2004-10-21 | 2006-04-28 | Monegasque Gouvernement | Swell attenuating device for protecting places e.g. harbors, has raft with perforations on part of its surface and placed between perpendicular upstream and downstream edges extended at their base by stubs of same determined length |
| US7585129B2 (en) * | 2004-10-21 | 2009-09-08 | Gouvernement Monegasque Represente Par Le Ministre D'etat | Refinement of the device for attenuating sea swell in the form of a so-called “camel's back” |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR580506A (en) * | 1923-07-11 | 1924-11-06 | Schneider & Cie | Piers or dikes at sea |
| FR1081798A (en) * | 1953-07-31 | 1954-12-22 | Improvements to floating maritime structures | |
| US2920454A (en) * | 1953-12-07 | 1960-01-12 | Edwin M Wolf | Apparatus for protecting offshore structures |
| FR1503543A (en) * | 1966-04-16 | 1967-12-01 | Grenobloise Etude Appl | Advanced training in wave protection works |
| WO1983003437A1 (en) * | 1982-04-01 | 1983-10-13 | Akai, Kazuaki | Purifying breakwater |
| WO1987002725A1 (en) * | 1985-10-23 | 1987-05-07 | GOUVERNEMENT MONEGASQUE, représenté par LE SERVICE | Method and device for attenuating the sea swell |
-
1990
- 1990-01-26 MA MA22002A patent/MA21740A1/en unknown
- 1990-01-29 IL IL93208A patent/IL93208A/en not_active IP Right Cessation
- 1990-01-30 EP EP90400246A patent/EP0381572B1/en not_active Expired - Lifetime
- 1990-01-30 ES ES90400246T patent/ES2060971T3/en not_active Expired - Lifetime
- 1990-01-30 TN TNTNSN90011A patent/TNSN90011A1/en unknown
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR580506A (en) * | 1923-07-11 | 1924-11-06 | Schneider & Cie | Piers or dikes at sea |
| FR1081798A (en) * | 1953-07-31 | 1954-12-22 | Improvements to floating maritime structures | |
| US2920454A (en) * | 1953-12-07 | 1960-01-12 | Edwin M Wolf | Apparatus for protecting offshore structures |
| FR1503543A (en) * | 1966-04-16 | 1967-12-01 | Grenobloise Etude Appl | Advanced training in wave protection works |
| WO1983003437A1 (en) * | 1982-04-01 | 1983-10-13 | Akai, Kazuaki | Purifying breakwater |
| WO1987002725A1 (en) * | 1985-10-23 | 1987-05-07 | GOUVERNEMENT MONEGASQUE, représenté par LE SERVICE | Method and device for attenuating the sea swell |
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2671569A1 (en) * | 1991-01-15 | 1992-07-17 | Doris Engineering | Method for installing a device for protection against the swell, and device resulting from the implementation of this method |
| ES2051194A2 (en) * | 1991-01-15 | 1994-06-01 | Doris Engineering | Method of installing protective device to big wave |
| FR2673213A1 (en) * | 1991-02-21 | 1992-08-28 | Sogreah | Break-water |
| FR2693216A1 (en) * | 1992-07-03 | 1994-01-07 | Doris Engineering | Reinforced or prestressed concrete sea swell protection barrier - comprises several caissons anchored on tubular struts and rear whirlpool basins with water openings protecting wall and top slab deck |
| WO1998029610A1 (en) * | 1997-01-03 | 1998-07-09 | Bouygues Offshore | Improvements to fixed partially immersed caisson dikes |
| FR2758147A1 (en) * | 1997-01-03 | 1998-07-10 | Bouygues Offshore | Semi=submerged caisson=type breakwater |
| FR2877022A1 (en) | 2004-10-21 | 2006-04-28 | Monegasque Gouvernement | Swell attenuating device for protecting places e.g. harbors, has raft with perforations on part of its surface and placed between perpendicular upstream and downstream edges extended at their base by stubs of same determined length |
| US7585129B2 (en) * | 2004-10-21 | 2009-09-08 | Gouvernement Monegasque Represente Par Le Ministre D'etat | Refinement of the device for attenuating sea swell in the form of a so-called “camel's back” |
| AU2005225112B2 (en) * | 2004-10-21 | 2011-01-20 | Gouvernement Monegasque Represente Par Le Ministre D'etat | Refinement of the device for attenuating sea swell in the form of a so-called "camel's back" |
Also Published As
| Publication number | Publication date |
|---|---|
| EP0381572B1 (en) | 1994-08-03 |
| TNSN90011A1 (en) | 1991-03-05 |
| IL93208A (en) | 1992-12-01 |
| ES2060971T3 (en) | 1994-12-01 |
| IL93208A0 (en) | 1990-11-05 |
| MA21740A1 (en) | 1990-10-01 |
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