EP0648897B1 - Noise reduction wall - Google Patents

Description

The present invention relates to a noise barrier intended to attenuate the perception of a noise source in a protected area, for example a residential area.

It was in 1972 that the first screens appeared acoustics built on the edge of road, motorway and rail, in most countries facing the noise problem; Germany, the United States, France, Great Britain and Japan were pioneers in the field.

We know that the effectiveness of a noise barrier depends, on the one hand, the acoustic quality of the materials used and the actual production called the work and, on the other hand, the dimensions (height and length) and the location of the noise barrier in relation to, respectively, the source of noise and the area of buildings to be protected.

Most noise barriers currently installed consist of concrete walls or metal sheet piles.

The downside of concrete walls is that due to the mass of this material, they are very heavy; such walls cannot therefore be laid on all floors, and especially not on backfilled floors, which are too loose.

In addition, the concrete walls are of an implementation very expensive.

Finally, since this implementation involves the use heavy and bulky equipment, it is not possible to build such walls when the site of their implantation is narrow, in particular on the ridges of slopes.

The implementation of a noise barrier from sheet piles have the advantage of being fast, of being less expensive and of suitable for all implantation sites.

In addition, the sheet piles of the finished work can be painted or decorated in such a way that the wall harmonizes with the environment or there confuses.

The major drawback of these two types of noise barrier nevertheless, they only reflect the noise, without absorbing it, because the concrete and steel are two materials that do not have the quality absorb, at least in significant quantities, the propagated sound.

In other words, the sound propagation wave is for the essentials reflected on the noise barrier built in concrete or by assembling metal sheet piles and it is returned in the direction of the source which is at its origin, up to sometimes a kilometer beyond this source.

We also know that wood is a good acoustic absorbent.

However, in most cases it is not possible to use this material directly, because of its mark of robustness and durability, characteristics which moreover are precisely those of the walls of concrete.

For several years, it has been proposed to use as absorbent material a cement and wood fiber compound, which therefore has both the durability and robustness that cement gives it, and the flexibility and lightness of the wood which, in the circumstances, replaces the sand or pebbles from traditional concrete.

In this material, marketed in particular under the in the form of square or rectangular panels, and known for example under the brand BBS (Concrete Wood System), wood, a living material, receives noise pollution and it absorbs them without retransmitting them.

But, in itself, the wall made from panels in BBS is not self-supporting.

Depending on the applications and the sites to be protected, the structure bearing of such a wall is then ensured either by precast concrete profiles, either by fire-galvanized steel pillars or by hollow posts of which the part planted in the ground is provided with orifices through which flows concrete injected into the ground, throughout the area surrounding the post, from the inside of the post, the concrete having been poured into the post under pressure a nozzle placed at the top of it. DE-A-42 12 172 describes this latest technique.

Some of the disadvantages outlined above do not are therefore not completely eliminated by the provision of such BBS walls, in particular the impossibility of pouring concrete profiles or installing steel pillars on embankment ridges and the impossibility of ensuring the proper maintenance of such walls on freshly backfilled soils, the weight of the concrete or steel pillars, increased the significant weight of the panels themselves, causing a; gradual darkening of such soils at the level of the foundations. The recommended technique according to patent DE-A-42 12 172 is also not sure because no one can assert, and cannot verify either that the concrete poured into the ground has remained in the area surrounding the part of the post planted in the ground.

However, with the appearance of new routes for highways and especially for high speed trains (TGV), there is an increasing need protect certain urban and rural areas from noise while, in the at the same time, the immediate surroundings of the noise sources appearing at traffic, especially that of TGV, do not allow, because of their narrowness, to build, in the form of concrete profiles or steel pillars, load-bearing structures of noise barriers that are highly reliable.

The present invention proposes to remedy all of the aforementioned drawbacks. It aims to optimize the establishment of a noise barrier designed to reduce the perception of a noise source in a area to be protected, regardless of the location and the type of soil of implantation.

In this context, the invention recommends the use of absorbent panels, of wood or of BBS type, therefore not self-supporting, the structure bearing such panels being obtained by the provision of thin metal posts, therefore robust but at the same time light, which can be installed in the ground anywhere, without the need for equipment heavy and bulky, therefore posts for quick installation - which can meet urgent work - and moreover reliable, robust and inexpensive.

The present invention first relates to a wall anti-noise composed of sound absorption elements, constituted by panels in an absorbent material, for example wood or BBS type, each of said absorbent panels being associated with a rigid support, and of a supporting structure supporting said elements and consisting of a plurality of posts arranged at substantially regular intervals along a line substantially parallel to the track, rail or road, to be isolated, each of said posts being provided staples which support said absorbent panels and whose position height on the post is adjustable, said wall rising at the edge of the track over a height greater than the distance separating the noise source from the ground in which it is installed, and being characterized in that the associated rigid support each panel is formed by a profile, preferably metallic, comprising a flat core with a loop along each of its two longitudinal edges horizontal, the upper loop of the support of each panel being able to cooperate by engagement, by horizontal longitudinal displacement, with the lower loop of the support of the upper level panel (s).

The fact that the supporting structure consists of posts guarantees the speed, simplicity and low cost of implementing a such structure as well as the adaptability of said structure to all types of terrain, consecutive to its lightness, on the one hand, and to its mode of implantation which does no need for special equipment, on the other hand.

The fact that the absorbent panels are supported by staples whose height position on each post is adjustable constitutes a guarantee in the continuity of the wall, the irregularities of the ground on which said wall is constructed being offset by an appropriate height of the staples.

In other words, depending on the height position which is given to the staples, one can also, gradually, from place to place along the noise barrier, easily compensate for differences in slope of the receiving terrain said wall.

In addition, the rigid support associated with each panel absorbent contributes to the robustness of the structure.

In a preferred embodiment, the width of the rigid support associated with each absorbent panel is at least equal to the height said panel. By thus giving the profile constituting the rigid support a width slightly greater than the height of the panel, we understand that we ensure to each panel a certain freedom of rotation around a horizontal axis relative to another panel, respectively upper and / or lower, which is immediately adjacent. Instead of being strictly in the same plane vertical, two adjacent panels can thus pivot relative to each other at an angle of up to 30 ° around the horizontal axis formed by the two loops, respectively lower and upper, engaged.

Advantageously, the rigid support associated with each absorbent panel is arranged on that of the two large faces of the panel intended to be placed opposite the plane formed by the line of posts.

According to yet another preferred construction, the absorbent panels are rectangular and longitudinally assembled to others by interlocking.

Advantageously, the absorbent panels are placed horizontally lengthwise and they are staggered. This horizontal arrangement of rectangular panels helps to eliminate any differences in slope of the terrain on which the noise barrier is built. It should also be noted that the panels of the same horizontal line are simply abutted, i.e. there is no imperative as to the fixing between them such absorbent panels located on the same level. Because of this last freedom, it is easy to understand that we can ensure continuity the noise barrier according to the invention exactly in parallel with the track to be insulated, both in its strictly rectilinear parts and in the curvilinear parts, namely in the wide bends made by road or rail. Indeed, two adjacent panels of the same horizontal line can be located in vertical planes which, between them, make an angle of a few degrees. In in addition, the arrangement of the staggered panels makes it possible to avoid the defect "of effect hinge "frequently encountered on all wall constructions in which, by construction obligation, all the panels are aligned in columns from the concrete or steel pillars.

According to another particularly advantageous construction, each of said posts consists of an open quadrangular tube longitudinally on that of its faces which faces the noise source, and clips to fix the sound absorption elements on the post are arranged in line with the opening of said post, so that said elements sound absorption are between the noise source and the pole line.

As a variant of this last construction, each of said posts consists of a quadrangular tube open longitudinally on the side which is furthest from the noise source, and the staples allowing the sound absorption elements to be fixed on the post at the opening of said post, so that the line of posts is between the noise source and said sound absorption elements.

These specific provisions of staples on posts facilitates their height adjustment for their appropriate positioning, in view of receiving at the right height the absorbent panel or panels which are to be associated to each of them.

According to a traditional construction particularly adapted to the production of the noise barrier according to the invention, each post is made in two parts, a hollow tubular base, stuck in the ground, and the post proper, including the lower part, intended to be forcibly engaged in the base, is straight and of a congruent and slightly outer section less than the internal section of said base.

In this last construction, the upper part the post which emerges from the base is advantageously of square or rectangular section, C-shaped, the opening of this C being framed longitudinally by two returns, substantially the same width, themselves formed of two wings, the first wings of these returns defining with the opening one of the four faces of the post and the second wings of said returns, which border the opening, being turned towards the inside of the post.

The supporting structure of the noise barrier to the aforementioned particularities is for all or part consisting either of posts essentially vertical, or vertical posts with a hanger at their top, either of vertical posts of which all the part which emerges from the base is curved, either of posts inclined for all or part on the vertical.

In the last four of the five aforementioned variants, the hangers and, respectively, the inclinations, of the poles are turned to the side the source of the noise to be eliminated. So these last four variants lead to anti-noise wall constructions which reflect the sound wave towards of the ground. The elimination of nuisances is therefore further improved.

Such constructions bent or tilted vertically are currently not achievable by the use of supporting structures BBS type panels formed from concrete pillars or from pillars galvanized steel.

According to a preferred embodiment, each clip is shaped like an S, the free part of this S extending upwards and being at its end folded back on itself, towards the opening of the post to which the clip is subject, to form a pin, said free part of the S fixing by the inside of its pin the end of the loop of the upper support which is attached to it associated and guiding and supporting from the outside of said pin the loop of the support which is also associated with it.

So with the exception of its staples of extreme levels lower and upper, the wall according to the invention has staples which are inserted in the interlocked loops of the supports of two panels.

The accompanying drawings, given by way of nonlimiting examples and purely illustrative, will allow a better understanding of the various characteristics of the invention and the advantages which it is capable of providing.

• la Figure 1 est un schéma théorique illustrant le principe de réaction d'un mur anti-bruit lorsqu'il reçoit une onde sonore,
• la Figure 2 montre l'application de l'invention à la lutte contre les nuisances sonores dues à la circulation d'un train à grande vitesse (TGV), le mur anti-bruit conforme à l'invention représenté à titre d'exemple étant du type entièrement cintré pour toute sa partie émergeant du sol,
• Les Figures 3a et 3b sont, respectivement, une vue de profil détaillée du mur anti-bruit de la Figure 2 et d'un ensemble absorbant, constitué d'un panneau absorbant et d'un support rigide, pour la variante de construction de la revendication 6 selon laquelle les éléments d'absorption acoustique sont placés entre la source de bruit et la ligne de poteaux,
• la Figure 4 représente schématiquement, vues de profil, les cinq variantes de conception de poteaux aptes à supporter les ensembles absorbants de la Figure 3b, pour ce qui est de leur partie émergeant du sol,
• la Figure 5 est, en perspective, une vue schématique de la disposition des poteaux du mur anti-bruit de la Figure 2 construit le long d'une voie ferroviaire,
• la Figure 6 est une vue de détail de la section arrachée d'un poteau et de la vis à tête spéciale permettant la fixation d'une agrafe,
• la Figure 7 est une vue de côté d'un assemblage vertical d'ensembles absorbants conformes à l'invention,
• la Figure 8 est une vue de côté, détaillée, de la liaison de deux ensembles absorbants dans un mur cintré au moins pour partie,
• la Figure 9 représente, vues en perspective, deux variantes de crochets permettant l'accrochage sur un poteau de l'ensemble absorbant supérieur du mur à réaliser, et
• la Figure 10 est une vue de face d'un mur conforme à l'invention, montrant la disposition en quinconce des ensembles absorbants.

On these drawings, which are part of the description:

• FIG. 1 is a theoretical diagram illustrating the principle of reaction of an anti-noise wall when it receives a sound wave,
• Figure 2 shows the application of the invention to the fight against noise pollution due to the circulation of a high speed train (TGV), the noise barrier according to the invention shown by way of example being of the fully curved type for all its part emerging from the ground,
• Figures 3a and 3b are, respectively, a detailed profile view of the noise barrier of Figure 2 and an absorbent assembly, consisting of an absorbent panel and a rigid support, for the construction variant of the claim 6 according to which the sound absorption elements are placed between the noise source and the line of poles,
• FIG. 4 schematically represents, in profile views, the five design variants of posts capable of supporting the absorbent assemblies of FIG. 3b, as regards their part emerging from the ground,
• FIG. 5 is, in perspective, a schematic view of the arrangement of the posts of the noise barrier of FIG. 2 constructed along a railway track,
• FIG. 6 is a detailed view of the section cut away from a post and of the special head screw allowing the fixing of a staple,
• FIG. 7 is a side view of a vertical assembly of absorbent assemblies according to the invention,
• FIG. 8 is a detailed side view of the connection of two absorbent assemblies in a curved wall at least in part,
• FIG. 9 shows, in perspective views, two alternative hooks allowing the upper absorbent assembly of the wall to be attached to a post, and
• Figure 10 is a front view of a wall according to the invention, showing the staggered arrangement of the absorbent assemblies.

We recall the principle of reaction of a noise barrier when it receives a sound wave, and in this regard, with reference to Figure 1, we know that a noise source placed at a point 1, above the ground 2, emits in all directions of the sound rays, and in particular, in the example considered, a beam of rays 3 towards an area to be protected diagrammed by the house 4.

• une partie 6 de l'onde est transmise à travers le mur 5,
• une partie 7 de l'onde est diffractée sur l'arête supérieure 8 du mur,
• une partie 9 de l'onde est réfléchie par le mur 5 du même côté que la source 1,
• une partie de l'onde est absorbée par l'écran, notamment lorsque ce dernier est en bois ou en composite du type BBS,
• une partie 10 de l'onde diffractée 7 est réfléchie sur le sol 2,
• enfin, une partie de l'énergie, notamment dans le cas d'une source sonore linéaire infiniment longue, tel le TGV, continue d'être perçue de façon directe aux extrémités du mur 5 : c'est l'énergie directe résiduelle.

To reduce such noise pollution, a wall 5 is placed between the source 1 and the area 4 so as to obscure the beam 3. Due to the interposition of the wall 5 between the source and the area to be protected, the propagation of sound is modified and its elementary paths are therefore defined as follows:

• part 6 of the wave is transmitted through wall 5,
• part 7 of the wave is diffracted on the upper edge 8 of the wall,
• part 9 of the wave is reflected by the wall 5 on the same side as the source 1,
• part of the wave is absorbed by the screen, in particular when the latter is made of wood or a BBS type composite,
• part 10 of the diffracted wave 7 is reflected on the ground 2,
• Finally, part of the energy, in particular in the case of an infinitely long linear sound source, such as the TGV, continues to be perceived directly at the ends of the wall 5: this is the residual direct energy.

It is in any event clear that the quality of a wall anti-noise is all the better as wave 6 transmitted through the screen is the as low as possible.

The noise barrier 5 must therefore absorb as much as possible of the transmitted energy.

The quality of an acoustic wall is in this respect characterized by "its transmission weakening index", or index R, which is expressed in third of an octave, in octave, or in dB (A), and which is defined as R = 10 Log I ₁ / I ₂ in which It is the acoustic intensity incident on the wall and I ₂ is the intensity transmitted by the wall.

We can see in Figure 2 the implementation of a first variant of an anti-noise wall according to the invention, in its application where the noise source is for example a high speed train 11 traveling on one and the other of the two channels 12.

TGV rail lines cause nuisance to local residents over distances of up to one kilometer from tracks 12.

After expertise, we realized that the noisy part of any TGV train 11 is at the level of all the rolling parts of the cars power cars and wagons, that is to say up to a height 13 of about one meter soil 2.

In order to capture and trap the noise emitted in one and / or the other of the beams 14, when the trainsets 11 pass on the tracks 12, there are on either side of the two tracks 12 an anti-noise wall identified by 15 as a whole.

Each of the anti-noise walls according to the invention comprises a supporting structure supporting acoustic absorption elements, said supporting structure consisting of a plurality of posts 16 arranged at substantially regular intervals along a line substantially parallel to the tracks 12. The vertices of the two lines of posts 16 define the vertices of the two walls 15. Each post 16 therefore rises above the ground 2 over a height H clearly greater than the distance h separating the noise sources 13 from the level of the tracks 12, c ' is to say clearly greater than one meter.

Advantageously, but without this condition being essential for the proper functioning of the wall 15, the top 17 of the latter is located at the bottom of the windows of the cars in the oar 11 so that the passengers 18 of this train looking horizontally along the arrow marked by 19 have not a vision obstructed by the walls 15.

a) soit rectilignes et verticaux, comme repéré par 116,

b) soit rectilignes et verticaux puis, à mi-hauteur ou plus près de leur sommet, inclinés en 216 sur la verticale, la partie inclinée étant, par rapport au plan du mur, tournée vers la ou les sources de bruit 13,

c) soit rectilignes et totalement inclinés par rapport à la verticale, comme repéré par 316, cette inclinaison par rapport à la verticale se faisant cette fois encore du côté de la source de bruit 13,

d) soit rectilignes et verticaux, puis, à mi-hauteur ou plus près de leur sommet, cintrés selon 416, la concavité de ce cintre étant orienté vers le sol 2, du côté de la source de bruit 13, comme indiqué par la flèche 417,

e) soit totalement courbes, comme repéré par 516, la concavité de la courbe de chacun de tels poteaux 516 étant orientée vers le sol 2, du côté de la source de bruit 13, comme indiqué par la flèche 517.

The posts of each line extending parallel to the tracks 12 can be of five different natures, as regards their part which emerges from the ground. Referring to this in Figure 4, they are:

a) either straight and vertical, as identified by 116,

b) either rectilinear and vertical and then, at mid-height or closer to their top, inclined at 216 vertically, the inclined part being, relative to the plane of the wall, turned towards the noise source or sources 13,

c) either rectilinear and totally inclined with respect to the vertical, as identified by 316, this inclination with respect to the vertical being again on the side of the noise source 13,

d) either rectilinear and vertical, then, at mid-height or closer to their top, bent along 416, the concavity of this hanger being oriented towards the ground 2, on the side of the noise source 13, as indicated by the arrow 417,

e) either completely curved, as indicated by 516, the concavity of the curve of each of such posts 516 being oriented towards the ground 2, on the side of the noise source 13, as indicated by arrow 517.

Whatever the construction variant chosen from the five mentioned above, each post 116, 216, 316, 416, 516 of such a supporting structure belongs to a vertical plane which extends substantially perpendicular to the direction D of the wall, therefore to the direction of the tracks 12.

We understand, by referring to the theory illustrated by Figure 1, that the walls whose supporting structure is built from any of the last four variants mentioned above are likely to refer to the ground, so that it is partly absorbed there, the reflected wave 9.

Whatever the shape 116, 216, 316, 416, 516 of the post chosen for its part emerging from the ground 2, said post, taken up then under its overall reference 16, is advantageously constructed from two elements: a straight tubular base 20, plugged into the ground 2, and the post 16 proper, of which the lower part 21 cooperates by an adjustment without play with the base 20, and to this end is therefore also straight.

Each base 20 is for example formed by a tube of square section, tube whose internal dimension on each side is 102 millimeters. The lower part 21 of the post 16 is congruent with the base 20, that is to say the same square shape as said base; each side of this part 21 of the post 16 then has an overall dimension of 100 millimeters, so that this part 21 can be forced into base 20.

Also preferably, the base 20 is bevelled according to 22 at its lower end, so that it can be more easily inserted into the ground 2. Said base is preferably also provided, on its parallel face at tracks 12 and the closest to said tracks, a trapezoid-shaped plate 23 isosceles whose large base is flush with the ground 2, the function of such a plate called " retained "being to improve the resistance of the bearing structure to the forces, so much in the wind.

Optionally, a second plate 24, likewise isosceles trapezoidal shape, whose short sides converge downwards, is associated at each base 20, near its end bevel 22, on the face opposite to that which is provided with the first retaining plate 23, in order to further improve the stress resistance characteristics of the bearing structure of the wall according to the invention.

Such bases are in themselves known and they are marketed under the brand "PROPICLO" .

The post proper, both in its part 16 which emerges from the base 20 only in its part 21 which is forcibly engaged in said base, is open longitudinally, for example on that of its faces 25 which is facing the tracks 12. The post thus has a section in C, the opening 26 of this C being framed longitudinally by two returns, substantially the same width, themselves formed of two wings, the first wings 27 of these returns defining with the opening 26 said face 25 facing the source 13 and the seconds wings 28 of said returns, which border the opening 26, being turned inwards of the post (Figure 6).

To absorb noise following the passage of trains 11 on tracks 12, the load-bearing structure defined above supports panels in an absorbent material, based in particular on wood, either pure wood, or and preferably of the BBS type.

Each absorbent panel 29 is preferably of rectangular shape, and very elongated. Each of said panels is associated with a rigid support 30 disposed on that of its two large faces 31 intended to be placed opposite the plane formed by the line of posts 16 (116, 216, 316, 416, 516).

The fixing of such a rigid support 30 on the panel 29 is obtained for example by the provision of screws and nuts shown diagrammatically in together by the axes 32, as can be seen in Figure 3b.

The assembly consisting of such a panel 29 and such rigid support 30 which is associated with it is identified by 33 on the wall 15.

The rigid support 30 is constituted by a profile, preferably metallic, whose length is equal to that of the panel 29 and whose width is at least equal to the height L of said panel. The section in question comprises a flat core 34 provided with a loop along each of its two horizontal longitudinal edges, the upper loop 35 being able to cooperate by engagement, by horizontal longitudinal displacement, with the lower loop 36 of the support 30 of the or sets 33 of the upper level.

In the rest of the description, for simplicity, the upper loop 35 will also be called the “female” loop and the loop lower 36 will also be referred to as a "male" loop.

To support such assemblies 33, each post 16 from the wall 15, in its part which emerges from the ground 2, is provided with staples 37 whose position height on the post is adjustable. These staples are shaped like S and they are arranged in line with the opening 26 of the post 16.

Each clip 37 shaped as S extends to the essential upwards, freeing itself from the post to which it is subject and, at its free part said clip is folded back on itself, at its end, towards of the opening 26 of the post, to form a pin 38.

Each clip 37 is fixed to the post 16 by the forecast a screw 39 with a particular head, whose dimensions and cut allow its engagement in the opening 26 of the post at C, then its blocking in rotation inside such a pole. To do this, the head of such a device 39, detailed in Figure 6, is formed of a base whose width is slightly less than the width of the opening 26 and whose length is substantially less than the dimension inside the side of the C-profile. The height of this base is less than the dimension interior of such a side reduced by the width of the second wings 28. Finally, one of the two large faces of such a base is provided with two rectilinear grooves 40, able to cooperate with the free edges 28 ′ of the second wings 28, and of a threaded rod 41 which extends orthogonally, substantially from the center of said face of the base. Between the two grooves 40, the base can advantageously be slightly lower than in its two 40 'parts which border on the outside said grooves.

Each clip 37 is pierced with an orifice allowing the passage of this threaded rod 41, and the assembly consisting of a clip and a screw special 39 is supplemented by a washer 42 and a nut 43 whose thread is complementary to that of the rod 41.

The fastening of the clip 37 on the post is obtained first by the introduction of the head of the screw 39 into the opening 26, by its dimension (width) narrowest, less than the width of said opening, then by the rotation (shown diagrammatically by the arrows 47) at 90 ° of this head so that it occupies its normal operating position shown in Figure 6. The base of the clip 37, substantially the same width as that of the side of the C profile, is then applied against the front face 25 of this profile 16, by progressive tightening of the nut 43 on the threaded rod 41. As this tightening takes place, the head of the screw 39 advances itself in the direction of this face 25 and the second wings 28 of the profile 16 penetrate the grooves 40, so that the head of the screw is this time locked in rotation.

It is thus understood that the clip 37 is easily adjustable in height position. When this position at the correct height is determined, the nut 43 is definitively tightened until the edges 40 'of the front face of the head of the screw 39 come to bear against the first wings 27 of the face before 25 of the C profile. Tightening is then effective. We have as many staples 37 on the post 16 that there are absorbent panels 33 to be supported by said post.

We will now describe in detail the assembly absorbent assemblies 33 on the posts 16.

First we have at the top of each post 16, on the front face 25 thereof, a hook 44 (Figure 9) whose top comprises two tabs 45 which penetrate the C-shaped profile, behind the face 25, of on either side of the second wings 28, and the base of which forms a return 46 towards the front and upwards, capable of receiving the female loop 35 from a first assembly 33. The assembly thus supported is supported by its lower part, say by its male loop 36, against the face 25 of the post 16. We then fix such an assembly 33 using a clip 37, making the end of the loop cooperate male 36 and the inside of the pin 38, and blocking in this ideal position the clip 37 on the post 16 by final tightening of the nut 43. It is clear that, for secure the end of the male loop 36 of the support 30 of the the assembly 33, the internal width of the pin 38 is barely greater than the thickness of the sheet from which said support 30 is profiled.

We know that the loops, respectively lower and of any support are complementary in shape, and that two supports can thus snap into each other, by longitudinal displacement horizontal.

When the first set 33 has been fixed to the post 16 as has just been said, there is a second set 33 on said post by making slide, by horizontal sliding, the upper loop 35 of such second set on the lower loop 36 of the first set attached. We notice that the pin 38 then guides and supports from the outside the female loop 35 of the second set 33 as the horizontal longitudinal displacement of it relative to the first set attached.

When the second set 33 is in place on the first set, we proceed to the fixing of said second set using a clip 37, repeating the operation seen previously, i.e. fixing by the inside of the pin 38 of this other clip 37 the end of the male loop 36 of the second set. The above operations are repeated for the third set 33 and for the following ones, until defining the last line of absorbent panels coming close to the ground 2.

We repeat, from post 16 to post 16, the operations previously seen in connection with the fixing of the assemblies 33.

It is thus understood that the assemblies 33 are integral from each other in the height direction, with however a degree of freedom around a horizontal axis 35-36, but that on the other hand such sets are independent of each other in the longitudinal direction, and that the panels 29 simply come to lean one behind the other by their vertical edges 48.

Since the panels are, in superposition, susceptible of deflections relative to each other around a horizontal axis 35-36, it is understood that, by the provision of panels 29 whose height L is slightly less than the overall width of the supports 30, it is possible to produce walls of which all or part has hangers 416 and 516. The slight interval 49 existing between two panels of two overlapping adjacent sets allows the relative travel of these two sets.

We also understand that, since in the sense of the length of the panels 29 are simply butted one behind the other, we can respect the turns of the channels 12 sources of noise to be isolated.

We also understand that, if we are located on these tracks 12, we only see the absorbent panels 29 of the walls 15 built, the posts carriers 16 and even the clips 37 supporting the panels being invisible on the track side.

It is also understood that the hooks 44 constituting the attachment member of the upper assemblies 33 of the noise barrier according to the invention can be of any other nature and they can, for simplification, be replaced by staples 37. The hooks can also be the first type mentioned above, and be two in number per post 16, the width of each hook 144 then being slightly less than the width of the wing 27 and the two legs 45 becoming one (Figure 9).

To allow easier mounting of the panels absorbent on the supporting structure 16, one can also proceed in two time.

Instead of delivering 33 fully assembled sets absorbent panels 29 and rigid metal supports 30, we can deliver separately the two elements of these sets and thus proceed to a first mounting, on the supporting structure, only metal supports 30. When these supports are in final position on the posts 16, then fixed to each support 30 an absorbent panel 29 using the devices diagrammed by the axes 32.

In other words, the assemblies 33 are either mounted in factory, or installed on site.

Finally, since the panels 29 are simply abutted one after the other in the longitudinal direction, one can provide a arrangement of such staggered panels.

An example of this staggered arrangement has been illustrated. in FIG. 10, where each panel 29 is offset by a third of its length by relative to the panel immediately above it and relative to the panel which is immediately lower.

Such an arrangement has a pitch P which is equal to the length of a panel 29. Provision is therefore made for burying posts while respecting the same pitch P , it being specified here that in the event that the pitch of the posts is not respected exactly, the offset is easily caught up in that, in their longitudinal position, the panels can be more or less moved relative to the clips 37 which support them.

For example, it is possible to provide panels 29 of four meters long and thirty three centimeters high, supported by poles 16 themselves arranged substantially every four meters.

Naturally, the invention is not limited to the mode of application no more than to the embodiments which have been mentioned and can design various variants without departing from its framework. So, the example of application was given along a railway track, but it is obvious that a noise barrier of the same kind can be placed at the edge of a road or motorway. It is also conceivable that, to alleviate the sound absorption structure 29-30, the rigid supports 30 are perforated with level of their souls 34. Such perforations, illustrated in FIG. 10 by the marks 50, reduce the weight of the assemblies 33, without affecting their acoustic quality since the supports 30 do not participate in the absorption of sound. Finally, in substitution of the construction variant illustrated in FIGS. 2, 3 and 8 according to which the opening 26 of each post 16 is turned towards the noise source, variant in which the sound absorption elements are arranged between said noise source and the line of poles, it is clear that the invention applies equally; ment to the construction according to which the opening 26 of each post 16 is provided on the one of the four faces of the post which is furthest from the source of noise. In this other variant, the line of posts is then between the source of noise and sound absorption elements; it is therefore the residents who then see from the constructed wall that the only absorbent panels; load-bearing posts 16 and the clips 37 which support the panels are invisible to residents and are only visible to people traveling on the tracks to be isolated.

Claims (15)

1. A noise reduction wall, intended to reduce the perception of a noise source (13) in an area to be protected, comprising: (a) sound-absorbing elements, consisting of panels (29) of absorbent material, particularly wood-based, each of said absorbent panels (29) being attached to a rigid support (30), and (b) a supporting structure (16) supporting said elements and consisting of multiple posts (16) positioned at substantially regular intervals along a line substantially parallel to the railway or roadway (12) to be isolated, each of said posts being equipped with hooks (37) which enable supporting the said absorbent panels (29), the height of whose position on the post (16) is adjustable, said wall being erected at the side of the way (12) to a height (H) greater than the distance (h) separating the noise source (13) from the ground (2) in which it is built, and characterised in that the rigid support (30) attached to each panel (29) consists of a section, preferably made of metal, said rigid support comprising a flat web (34) equipped with a curled lip along each of its longitudinal horizontal edges, the upper curled lip (35) of the support (30) of each panel (29) being adapted to co-operate by interlocking, by longitudinal horizontal displacement, with the lower curled lip (36) of the support (30) of the panel(s) (29) of the next level up.
2. A noise reduction wall as claimed in Claim 1, characterised in that the rigid support (30) attached to each panel (29) is of a width at least equal to the height (L) of the panel.
3. A noise reduction wall as claimed in Claim 1 or Claim 2, characterised in that the rigid support (30) attached to each panel (29) is located on the one (31) of the two major faces of the panel which is to be positioned facing the plane formed by the line of posts (16).
4. A noise reduction wall as claimed in any one of Claims 1 to 3, characterised in that the absorbent panels (29) are rectangular and assembled lengthwise with respect to one another by interlocking.
5. A noise reduction wall as claimed in any one of Claims 1 to 4, characterised in that the panels (29) are positioned lengthwise horizontally and are staggered.
6. A noise reduction wall as claimed in any one of Claims 1 to 5, characterised in that the absorbent material is made of cement and wood fibre.
7. A noise reduction wall as claimed in any one of Claims 1 to 6, characterised in that each of the said posts (16) consists of a four-edged tube open longitudinally on the one of its faces which faces the noise source (13), and in that the hooks (37) enabling fixture of the acoustic elements (29) on the post (16) are arranged opposite the opening (26) on the said post so that the said sound absorbing elements are between the noise source and the line of posts.
8. A noise reduction wall as claimed in any one of Claims 1 to 6, characterised in that each of the posts (16) consists of a four-edged tube open longitudinally on the one of its faces which is the farthest from the noise source (13), and in that the hooks (37) enabling fixture of the acoustic elements (29) on the post (16) are arranged opposite the opening (26) on the said post so that the line of posts is between the noise source and the said sound absorbing elements.
9. A noise reduction wall as claimed in Claim 8, characterised in that each post (16) is, in conventional fashion, made in two parts, a hollow tubular footing (20), fixed in the ground (2), and the post proper (16), whose lower part (21), intended to be a force fit in the footing (20), is straight and has an external cross-section congruent with and slightly smaller than the internal cross-section of the footing.
10. A noise reduction wall as claimed in Claim 9, characterised in that at least the upper part (16) of the post emerging from the footing (20) is of square or rectangular C-shaped cross-section, the opening (26) in the C being edged along its length by two returns, of substantially the same width, themselves formed of two flanges, the first flanges (27) of the two returns defining, together with the opening (26), one (25) of the four faces of the post and the second flanges (28) of the said returns, bordering the opening (26), being turned back towards the interior of the post (16).
11. A noise reduction wall as claimed in any one of Claims 1 to 10, characterised in that its supporting structure consists, at least in part, of posts (416) whose upper part, emerging from the footing (20) is, from bottom to top, first vertical and straight, and then curved, the concavity (417) of this curve facing towards the ground, on the noise source side.
12. A noise reduction wall as claimed in any one of Claims 1 to 10, characterised in that its supporting structure consists, at least in part, of posts (216,316) inclined wholly or partly to the vertical, said inclination being turned towards the noise source (13), and the plane in which is located each post being substantially perpendicular to the said wall.
13. A noise reduction wall as claimed in any one of Claims 1 to 10, characterised in that its supporting structure consists, at least in part, of posts (516) whose entire upper part emerging from the footing (20) is curved, the concavity (517) of the curve of each of the said posts facing towards the ground (2) on the noise source side (13), and each curved post (516) belonging to a plane substantially perpendicular to the said wall.
14. A noise reduction wall as claimed in any one of Claim 1 to 13, characterised in that each hook (37) is S-shaped, the free part of the S extending upwards and being, at its end, folded back on itself, in the direction of the opening (26) of the post (16) to which the hook (37) is fixed, to form a pin (38), the free part of the S fixing, with the inside of the pin, the end of the curved lip (36) on the upper support to which it is attached and guiding and supporting via the outside of the said pin (38), the curved lip (35) of the lower section, which is also connected to it.
15. A noise reduction wall as claimed in Claim 14, characterised in that with the exception of its hooks (44,37) at the top and bottom levels, the said hooks are interposed in the interlocked curved lips (35,36) of the supports (30) of two panels (29).

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