WO1998012387A1

WO1998012387A1 - Sound barrier

Info

Publication number: WO1998012387A1
Application number: PCT/SE1996/001175
Authority: WO
Inventors: Peter Bergendahl
Original assignee: Gunnebo Industries AB
Current assignee: Gunnebo Industries AB
Priority date: 1996-09-23
Filing date: 1996-09-23
Publication date: 1998-03-26
Anticipated expiration: 1999-03-23
Also published as: AU7510796A

Abstract

Roads (1) with heavy traffic are provided on either side with wall-like units (2, 3) of various materials. The present invention relates to a new unit that can be prefabricated, is rectangular, consists of supporting panel (4) which is provided on one or both sides with a sound-reducing layer (5). Between the layer (5) and the supporting panel (4) is arranged either an air gap (26) or a sound-absorbing layer (12) or both. The supporting panels (4) may also have sound-reducing properties.

Description

S O U N D B A R R I E R

Free-standing walls or barriers, which may be made of various materials, are arranged between the buildings on either side of roads with heavy traffic and the actual road. The walls may also consist of units that are fitted together in one way or another.

The object of the present invention is to produce a sound barrier designed, with the aid of uprights, to form a coherent wall. The object of the invention is also to produce prefabricated barriers with high sound-reducing effect. According to the invention a barrier is substantially rectangular and consists of at least two layers, one layer being a supporting layer and the other being a sound-reducing layer. The supporting layer may consist of a panel produced from a timber such as pine or spruce, preferably pine.

The panel may also be constructed of planks, preferably matched plank or with overlapping parts. The panel may itself be sound-reducing, in which case the thickness of the panel may be varied depending on the desired sound-reduction. The panel is also impregnated with an environmentally approved composition.

The material of the sound-reducing layer is selected to obtain sound- reduction and this can also be obtained by means of depressions, such as grooves in the layer. Suitable material for the sound-reducing layer is a panel selected from a timber choice of either pine or spruce. Other materials, such as fibreboard, are also feasible.

A layer of mineral wool or foam plastic is arranged between the two layers. The thickness of the layer can be regulated. An air gap is arranged between the layer or mineral wool and the supporting panel, the width of which may be varied within desired limits. The sound- reducing layer may be replaced with a number of parallel ribs, which may have rectangular cross-section and be spaced from each other, and be arranged horizontally, vertically or inclined. Said rectangular barriers are designed for attachment to two uprights anchored in the ground, at least alternate uprights being higher than the upper edge of intermediate barriers. The upper edge of two uprights is provided with a unit of strip-like material shaped to provide sound reduction. Each upright consists of a core unit, preferably of metal, the core unit generally being tubular. The core unit is anchored in the best possible way by its lower end in a ground foundation to provide stability. The core unit of an upright has two large opposing cover plates partially covering adjacent barriers.

Additional features of the present invention are revealed in the appended claims.

The invention will be described in more detail with reference to six sheets of drawings in which

Figure 1 shows a wall section with two different sound barriers seen from one side, Figure 2 shows the same object as in Figure 1 but seen from another side, Figures 3-4 show a wall seen from two sides, constituting a first type of noise protection, Figures 5-6 show a wall of a second type of noise protection, Figure 7 shows an exploded view of a wall of the first type,

Figure 8 shows an exploded view of the second type of noise protection, and Figures 9-10 show a protective strip for the top edge of a wall seen from above and below, respectively.

Figures 1 and 2 show a road section designated 1 with two noise- reducing barriers 2 and 3. Each barrier is composed of two screens or wall elements. The wall 2 in Figure 1 consists of two layers, a supporting layer 4 and a second layer 5. In this case it is primarily the second layer that is panel-shaped and noise-reducing. The actual panel may be flat or provided with depressions. It has been found that the supporting layer may also be noise-reducing, in which case it is suitably made as a panel of wood or in the form of planks joined together either with tongue-and-groove jointing or with overlapping parts. Various types of timber are possible such as spruce and pine, the more preferable being pine. When the supporting layer is sound-reducing, the second layer may consist of parallel ribs spaced from each other and preferably having rectangular cross section. The ribs may be inclined as shown in Figure 1, or vertical. Horizontal ribs are also feasible. This wall 2 acts only as a noise-reducing wall. Figure 3, on the other hand, shows said two layers 4' and 5' as in Figure 1, but with a sound- absorbing layer 12 between the two layers. The layer 12 may consist of mineral wool, foam plastic or other materials having sound-reducing properties. The wall 3 also includes an air gap between the sound- reducing layer 12 and the supporting wall 4'. Thus, the wall 3 according to Figure 3 is not only noise-reducing but also sound-absorbing. It has been found most suitable to arrange both a layer of mineral wool 12 and an air gap between the two layers 4' and 5'. Naturally it is possible to use either of these two partitions between the layers 4' and 5'.

As is clear in Figure 1, each wall consists of two elements or barriers applied between two uprights. It is thus clear that three uprights are required for each wall element, where the middle upright is shorter. Above the two layers is a coping 19 in the nature of a channel and this coping has also proved to contribute to reducing the sound passing through the wall. Figures 3 and 4 show the wall 2 consisting of two layers, seen from different directions, and Figures 4 and 6 show the wall with both sound-absorbing layers and air gap between the two layers 5' and 4'.

As can be seen in Figures 3-6, the lower end of each upright is anchored in a hole at ground level surrounding the upright with a cement block 9, 10 and 11, respectively, which may also be reinforced and are cast on site. For a better understanding of Figure 2, Figure 7 shows an exploded view of a sound-reducing wall having two layers. The figure thus reveals the supporting layer 4 consisting of planks combined to form a panel. The planks may be joined by tongue-and-groove joints or by means of overlapping. The planks are red deals impregnated with an environmentally approved composition, class AB, and the panel produced fulfils acoustic requirements PrEN 1793 PARTS 1-3, class B2. The mechanical properties of the planks fulfil the requirements according to PrEN 1794 PART 1 and PART 2. Spacers 15, 16, 17 and 18 are arranged at the back of the panel 4. The second layer consists of parallel wooden strips 5 with rectangular cross section which are applied on the panel 4 in the most suitable manner. The ribs are suitably of pine, spruce or a suitable timber and are also impregnated and framed by two strips 13 and 14. As shown in Figure 1, the ribs 5 may also be arranged inclined or horizontal. When the two layers 4 and 5, and also the spacers 15-18, are combined a coping 19 which also contributes to the sound-reduction, is placed over the wall section. The coping, which can also be said to constitute a roof over the two layers 4 and 5, may be made of sheet metal, plastic or other similar material. Considering Figures 9 and 10, it can be seen that the coping 19 is composed of four roof-like units 29, 30, 31 and 34. The parts 32, 33, 35 and 36 of the sheet metal are folded to form an opening 28 that covers the two layers plus the spacer elements 15.18 in Figure 7. It should be noted here that parts of the coping extend outside both lateral surfaces of the layers 4 and 5.

As is clear from Figure 1, each wall requires three uprights and Figure 7 illustrates clearly how an upright is constructed. It comprises a core part 20, suitably made of metal, having rectangular cross section and being tubular. The core part is then provided with two cover plates 22 and 23 and a roof or lid of suitable material such as sheet metal, plastic or the like is placed on top of the core unit. When the wall section to the right of the upright in Figure 7 is joined to the upright, the cover plates 22 and 23 will also cover the vertical edges of the wall section. As is clear in Figure 1, both end uprights are the same as that just described, whereas the top of the middle upright coincides with the upper edge of the wall element.

Figure 8 shows a wall section like the wall 3 in Figure 1, consisting of an outer layer 5' with a surrounding frame 25. Inside the layer 5' is a sheet of mineral wool, foam plastic or the like, with sound-absorbing properties. This sheet is surrounded by a frame 27 and the supporting layer 4' consisting of pressure-impregnated planks which are sound- reducing and provided with a number of spacer elements 26 of suitably dimensioned wood. These spacer elements ensure that when the wall barrier is put together it will consist first of the layer 5' and immediately thereafter the sheet of mineral wool 12 surrounded by the frame 27. The spacer elements 26 rest on the mineral wool so that an air gap is formed between the mineral wool 12 and the layer 4'. Both air gap and mineral wool contribute to producing a sound-absorbent effect. The upright is the same as in Figure 7 and will not therefore be described again.

It is advisable to pressure-impregnate timber products with an environmentally approved composition according to class AB.

Uprights and wall elements shall also fulfil the acoustic requirements of PrEN 1793 PARTS 1-3, class A3/B-3. Assembly of each wall shall be such that they fulfil the mechanical requirements of PrEN 1794 PARTS

1-2. The coping may consist of plastisol SC 180μM. The barriers or walls in Figures 3 and 4 have been tested at the Swedish National

Testing and Research Institute in Boras. The supporting layer had a thickness of approximately 28 mm and the sound reduction at the test was approximately 21.2 dB. The supporting layer may of course be thicker than 28 mm. Technical experiments have been carried out on the coping at Akustisk Analys AB indicating that a noticeable reduction in sound is obtained with the coping according to Figures 9 and 10.

A wall 3 according to Figure 1 was also subjected to the same experiments as the wall 2 where the result was the same for the coping, but where it was found that with an air gap of 20 mm and a sheet of mineral wool 50 mm in thickness, a total reduction in sound is obtained of approximately 32 dB.

It should be obvious that the width of the air gap, the thickness of the sheet of mineral wool and that of the supporting layer 4' may be varied within wide limits in order to achieve the desired reduction in sound or noise.

The two walls 2 and 3 shown in the drawings thus consist of three uprights and two intermediate panels. Both the intermediate panels and the uprights can be prefabricated at the factory. A wall 2 having only sound-reducing properties and a wall 3 having both sound- reducing and sound-absorbing properties can thus be quickly be assembled.

Claims

1. A sound barrier, panel, wall or the like designed to face an area generating sound, said barrier, panel, wall or the like reducing the sound level of sound passing through it, characterized by a supporting panel (4) on at least one side of which is applied a layer (5) having sound-reducing properties.

2. A sound barrier as claimed in claim 1, characterized in that the supporting panel (4) is produced from a timber such as spruce, pine or the like.

3. A sound barrier as claimed in claim 1, characterized in that the panel (4) per se is sound-reducing.

4. A sound barrier as claimed in claim 3, characterized in that the panel (4) is constructed of planks, preferably matched plank or with overlapping parts.

5. A sound barrier as claimed in claims 3 and 4, characterized in that the panels (4) are given a predetermined thickness and are preferably impregnated.

6. A sound barrier as claimed in claim 1, characterized in that the layer (5) is provided on its outer side with one or more depressions, preferably in the form of recessed grooves which may be straight or crooked.

7. A sound barrier as claimed in claim 1, characterized in that the layer (5) is produced from sound-reducing material such as a timber choice of either pine or spruce.

8. A sound barrier as claimed in claim 1, characterized in that the layer (5) consists of a panel such as a wooden panel.

9. A sound barrier as claimed in one or more of the preceding claims, characterized in that an air gap (26) of predetermined width is arranged between the layer (5') and the supporting panel (4')-

10. A sound barrier as claimed in one or more of the preceding claims, characterized in that a layer (12) of sound-reducing material with predetermined thickness, such as mineral wool or foam plastic is arranged between the outer layer (5') and the supporting panel (4').

11. A sound barrier as claimed in claims 9 and 10, characterized in that a sound-absorbing layer (12) and an air gap (26) are arranged between the outer layer (5') and the supporting panel (4').

12. A sound barrier as claimed in claim 1, characterized in that the sound-reducing layer (5") is replaced with a network or with a number of parallel ribs, preferably having rectangular cross- section and spaced from each other, and being arranged horizontally, vertically or inclined and consisting of timber such as spruce or pine.

13. A sound barrier as claimed in one or more of the preceding claims, characterized in that a channel-like unit (19) is arranged along a part, parts or around the entire periphery of the barrier, said units being sound-absorbing and the peripheral edge protruding into the channel itself.

14. A sound barrier as claimed in claim 13, characterized in that the unit (19) is formed by a strip of preferably metal.

15. A sound barrier as claimed in claim 13, characterized in that the strip is shaped having inclined surfaces (31-33) designed so that the unit (19) extends outside both sides of the barrier (2, 3')-

16. A sound barrier as claimed in one or more of the preceding claims, characterized in that the barrier has at least two opposite parallel edges designed for attachment to an upright (6, 7, 8) anchored in the ground, the number of uprights being possibly more than two to allow a wall of the desired length to be erected.

17. A sound barrier as claimed in claim 16, characterized in that at least alternate uprights (6 and 8) are taller than the intermediate barriers.

18. A sound barrier as claimed in claim 13, characterized in that the upper edge of said intermediate barriers is provided with said channel-like units (19).

19. A sound barrier as claimed in claim 16, characterized in that each upright (6) is provided with a core unit (20), preferably of metal, is tubular and has two large opposing cover plates (22 and 23) partially covering adjacent barriers.