GB2264316A - Noise barrier - Google Patents

Abstract

A noise barrier comprises a member 4 or members 4, adapted to be mounted upright e.g. by means of an I-section pillar to form a screen. The or each member 4 is provided with or constitutes a plurality of Helmholtz resonators 6, 10 which open to a exposed face 2 of the barrier for absorbing noise incident thereon. <IMAGE>

Description

NOISE BARRIER This invention relates to noise control and in particular to barriers for controlling noise generated on highways.

It is known to provide means for controlling noise on motorways, for example. Typically, measures taken in the past have included simple concrete barrier walls, timber noise barriers constructed from timber boards suspended between posts and even barriers formed from mounds of earth or formed by planting trees. Although such barriers serve to insulate against noise generated by highways, they have generally proved to be far from ideal.

For example, simple concrete barriers can require a substantial amount of concrete to be used in order to render the barrier effective, furthermore substantial foundations are required. Timber barriers can be prone to weathering, causing decay and failure, and can also represent a fire hazard. Trees are far from satisfactory and are particularly susceptible to localised sound leakage between individual trees.

One further disadvantage of the above sound barriers is that they tend to cause what is known as the "canyon effect", which results in a generation of excessive noise due to multiple reflection across the road. This can be very uncomfortable for road users as well as those in the general locality.

The present invention sets out to provide a noise barrier which offers good sound insulation qualities and good sound absorption qualities whilst reducing the concentrated effects of sound leakage. Furthermore, the invention sets out to provide a barrier which does not require cumbersome and expensive concrete foundations, and which is robust and not liable to decay or catch fire.

According to the present invention there is provided a noise barrier comprising a member or members, adapted to be mounted upright to form a screen, provided with or constituting a plurality of Helmholtz resonators open to an exposed face for absorbing noise incident thereon.

Preferably the noise barrier is composed of a plurality of substantially upright posts and a plurality of concrete planks extending between the said posts to define a wall; each said plank being provided with a plurality of Helmholtz resonators.

In a preferred embodiment each said plank is integrally formed with a plurality of respective Helmholtz resonators.

In another embodiment of the invention the Helmholtz resonators are defined by blocks, a predetermined number of which are cast onto a respective one of the concrete planks prior to installation in the said sound barrier, each block comprising two resonator cavities, two openings on a first side thereof, and formations on a second side thereof for keying with the concrete planks when cast on the planks, each of the said openings being in communication with a respective one of the said cavities.

Preferably the formations are dovetail grooves.

The cavities may be void or may be partially or completely filled with a filler such as a fibrous filler.

Preferred embodiments of the invention will now be described by way of example and with reference to the accompanying drawings in which: Figure 1 is a partial elevation of a plank and block unit in accordance with the invention; Figure 2 is a section through the plank and block unit of Figure 1; Figure 3 is a partial plan view of the plank and block unit shown in Figure 1; Figure 4 is a view of part of a barrier in accordance with the invention and incorporating plank and block units in accordance with Figure 1; Figure 5 is a section showing part of two plank and block units from Figure 4 in combination with a support pillar also in accordance with the invention; Figure 6 is a perspective view of a block in accordance with the invention; and Figure 7 is a plan view of the underside of the block shown in Figure 6.

Figures 1 to 3 show a series of concrete blocks 2 fitted to a concrete backing plank 4. Each block comprises a front face 20, a rear face 12 and two side faces 18.

Each block is also faced with an end face 22. The block is divided inside by a wall 8 which forms a pair of inner cavities 6. Each inner cavity is defined by part of the rear face 12, part of the front face 20, one of the side faces 18 part of the end face 22; and the wall 8. The front face further comprises a pair of openings 10, one communicating with each of the cavities 6. Each opening extends from the open end 24 of the block and part-way towards the closed end face of the block 22.

Each opening 10 is generally elongate.

The rear face of each block is provided with a central dove-tail groove 14 which extends from the closed end face 22 of the block to the open end of the block. A partial dove-tail groove is provided at each of the junctions between a respective one of the side faces 18 and the rear face 12 of the block.

Prior to installation, to form each block and plant unit, the blocks are cast onto a reinforced concrete plank 4 and are secured in place by means of the concrete of the plank 4 setting around the dove-tail grooves 14 and 16, which serve to key the blocks into the concrete of the plank 4.

It should be noted that adjacent blocks are placed with their side faces 18 in contact in side-to-side relation, and in end-to-end relation with their respective sealed end faces 22 in contact. The blocks in successive rows are staggered in the longitudinal direction of the plank.

To form the barrier, as can be seen from Figure 4, pre-cast concrete I-section pillars are set in concrete 42 in augered holes in the ground. The holes must be of sufficient depth to resist overturning movements experienced under lateral wind loading. The planks are received within channels 41 in the pillars and are stacked one above the other in a vertical direction.

The cavities 6 may be void, partially filled with, for example, fibrous filler, or fully filled.

Each cavity 6 and associated opening 10 described above defines a Helmholtz resonator.

As an alternative embodiment, rather than casting separate blocks onto the front of a respective plank, the plank and block unit may be formed as a single unit in the form of a plank comprising a series of integrally formed cavities, each cavity having a configuration similar to that of the cavities of the blocks described above.

In use, the barrier is constructed with the openings of the resonators directed towards the source of the noise. The resonators when void serve to absorb the acoustic energy, or when filled with filler 32 or partially filled with filler 30 dissipate acoustic energy. The absorption or dissipation of the acoustic energy serves to reduce reverberation times and reverberant sound pressure levels, effectively serving to reduce the length of time for which sound can bounce across the road from one side to another. At the same time, the dense nature of the composite units and particularly the concrete planks 4 insulates from the noise and yields excellent sound insertion loss figures.

Thus it can be said that a barrier in accordance with the invention can firstly insulate against noise and secondly reduce the level of noise coming into contact with the insulating surface by absorbing sound and reducing reflection and particularly the "canyon effect", thus maximising insulation. The insulation serves to reduce noise levels for occupants of buildings in close proximity to the highway, and the reduction of the canyon effect makes the road less noisy for road-users.

Although the above described pillars 40 are formed from concrete they could alternatively be in the form of galvanised universal columns.

A typical block in accordance with the invention could have a front face of 440mm by 215mm. The concrete backing could suitably be 100mm thick.

Due to the homogenous nature which the barrier can be given, by constructing it as described above, the concentrated effects of sound leakage are reduced.

Because the barrier can be constructed by the use of augered foundations and pillars and planks, cumbersome and expensive concrete foundations are not necessary, which leads to improved efficiency in the form of rapid and economic construction. The barrier also serves to resist lateral wind loading.

Furthermore, the barriers can be provided with coloured and textured finishes capable of harmonising with the local surroundings.

The barriers are robust and durable, require minimum maintenance and have excellent fire resistant properties.

The above described components represent a straight forward supply and erect system which generally facilitates all aspects of the provision of a sound barrier. This also leads to improved construction efficiency.

Although the invention has been described in the context of sound reduction on highways, the invention will find many other applications in, for example, airports, railways and other such high-noise situations.

Many other advantages and modifications will suggest themselves to those versed in the art upon making reference to the foregoing, which is given by way of example only and is not intended to limit the scope of the invention in any way.

Claims (17)

1. A noise barrier comprising a member or members, adapted to be mounted upright to form a screen, provided with or constituting a plurality of Helmholtz resonators open to an exposed face of the barrier for absorbing noise incident thereon.

2. A noise barrier according to claim 1, wherein the or at least one member comprises a plank.

3. A noise barrier according to claim 2 wherein the or each plank is mounted on one or more substantially upright posts with its longitudinal axis arranged generally horizontally.

4. A noise barrier according to claim 2 or 3, wherein the or each plank is integrally formed with a respective plurality of Helmholtz resonators.

5. A noise barrier according to claim 4, wherein the or each plank and respective Helmholtz resonators are formed from concrete.

6. A noise barrier according to claim 2 or 3, wherein the or each plank has a plurality of Helmholtz resonators fitted thereto.

7. A noise barrier according to claim 6, wherein the Helmholtz resonators are formed within blocks.

8. A noise barrier according to claim 7, wherein the or each plank is formed from concrete and respective ones of the said blocks are cast onto a one of its faces.

9. A noise barrier according to claim 8, wherein each block is provided with a keying formation on one side thereof for keying with a respective concrete plank when cast onto the plank and with a Helmholtz resonator opening on a second and opposite side thereof.

10. A noise barrier according to claim 9, wherein each keying formation is in the form of a dove-tail groove or a dove-tail projection.

11. A noise barrier according to any one of claims 7, 8, 9 or 10, wherein each block comprises two Helmholtz resonators.

12. A noise barrier according to any preceding claim wherein the resonance cavity of at least one of the Helmholtz resonators is at least partially filled with a filling material.

13. A noise barrier according to claim 12, wherein the filling material is a fibrous filler.

14. A noise barrier according to claim 6 or any claim dependent thereon, wherein the Helmholtz resonators provided on each plank are arranged in two rows along the length of the plank.

15. A noise barrier according to any preceding claim, wherein each Helmholtz resonator is in the form of a chamber which opens into the said exposed face of the barrier via a slit.

16. A noise barrier according to claim 15 dependent on claim 7 or any one of claims 8 to 15 when dependent on claim 7, wherein each slit extends from one end of a respective block, partially towards an opposite end of the block.

17. A noise barrier substantially as herein described with reference to the Figures of the accompanying drawings.