GB2394903A

GB2394903A - Artificial sports surface

Info

Publication number: GB2394903A
Application number: GB0225919A
Authority: GB
Inventors: Malcolm John Dorman
Original assignee: Individual
Current assignee: Individual
Priority date: 2002-11-06
Filing date: 2002-11-06
Publication date: 2004-05-12
Also published as: GB0225919D0; GB2395135B; GB0325610D0; GB2395135A; WO2004042148A1; AU2003301895A1

Abstract

A multi-layered synthetic sports surface comprises a supporting sub-layer 5, which has a generally smooth upper-surface and is formed by a plurality of adjacent box-channel units. Above this, there is a cover layer 1 fixedly attached over said supporting sub-layer. Additionally there is provided a method for construction of such a sports surface. Holes 14 may be provided in the upper surface of the sub-layer 5 to allow drainage of water directly into the channels 9. A piping system 15 may be provided within the channels 9 connecting pump unit 16 and sprinkler heads 17.

Description

1 2394903

Artificial Sports Surface The present invention relates to a synthetic sports surface suitable for both indoor and outdoor all weather use. The invention further relates 5 to a method for construction of the same.

When laying a sports surface of either natural or artificial grass by traditional methods, high costs are usually incurred. The majority of these costs are concerned with preparation and construction of the underlying 10 base materials. In particular it is necessary to provide an adequate drainage system as well as to maintain the upper surface layers away from lower foundation materials such as clay. In most cases this is achieved through the use of two separate systems, namely: separation layers to prevent rise and fall of potentially migrating sub-layers; and 15 provision of adequate drainage, normally requiring drainage trenches, reservoirs and various levels of substrates. Such systems are expensive to construct both in material costs and in the labour hours required, typically entailing the removal and/or levelling of thousands of tonnes of material. Not only this but once the surface layers have been laid, 20 maintenance of the underground network is expensive and disruptive.

Furthermore, very few artificial surfaces existing on the market have been able both to provide adequate drainage and at the same time withstand the high energy impacts associated with modern sports, leading to degradation of the playing surface and the risk of serious injury to the 25 athletes. Previous efforts have been made to resolve some of the problems discussed above. In particular, there exists a multitude of proposals for tackling the problems of drainage and separation layers. Many are similar 30 to United States Patent 4,462,184, wherein a synthetic surface is laid atop a particulate subsurface base system, said base system incorporating two layers, the upper allowing mostly downwardly drainage, the lower

predominantly horizontal drainage. Below this is an impermeable separation layer, preventing transport of migrating materials from the underlying subgrade. Alternatively, United States Patent 4,501,420 has a synthetic surface on top of a sand layer, allowing vertical drainage, 5 beneath which is the largely impermeable ground layer that has drainage channels excavated and filled with material that allows mainly lateral drainage. United States Patent 5,460,867 discloses a separation layer for 10 laying real or artificial grass surfaces onto sand or gravel, consisting of a dimpled, rigid-plastic layer covered by flexible matting. This provides some directional drainage guided by bridges between dimples of the separation layer, and prevents upward migration of materials in the underlying subgrade.

United States Patent 6,221,445 describes a composite artificial turf structure, comprising an upper layer of artificial grass atop a deflection layer providing shock absorption qualities. This lies on a sand-filled cellular grid structure providing drainage and stability for the layers above.

20 A separation layer is required below the grid system in order to prevent material migration and sinking of the surface.

It is an object of the present invention to provide a synthetic sports surface requiring little or no ground preparation in advance of 25 construction. A second object of the invention is to enable rapid, easy manufacture and construction of the sports surface from relatively low cost materials.

According to one aspect of the invention there is provided a 30 synthetic sports surface comprising: a supporting sub-layer, having a generally smooth upper surface, formed by a plurality of adjacent box

channel units; and a cover layer fixedly attached to the supporting sub-

layer. Preferably the box-channel units are laid so as to provide a network 5 of lateral channels, affording natural drainage of water passing downwardly into the channels.

In one embodiment, the cover layer is an artificial-turf-carpet. In another embodiment, a linoleum type material is used.

It is preferable in most (but not all) cases where the cover layer is an artificial-turf-carpet that sand is interspersed amongst the pile of said artificial-turf-carpet to a prescribed depth. Similarly, a mixture of sand and rubber granules could be interspersed amongst the pile of said artificial 15 turf-carpet. These help to stabilize the pile of the turf and may add to the shock absorbing properties of the surface.

Expediently, the box-channel units are of synthetic plastics material. This enables simple and inexpensive manufacture of the units 20 and provides the necessary degree of durability and elasticity. Most preferably, the synthetic plastics material is high density polyethylene which has particularly desirable properties in this respect. An advantage of this kind of material is that its flexural behaviour acts in a similar manner to a sprung wooden floor, as may be advantageous when used as 25 an indoor sports floor. When used in conjunction with an artificial-turf-

carpet, with sand or a sand-and-rubber-granule mixture distributed amongst the pile of said carpet, the flexural motion of the floor prevents the grains compacting, maintaining a softer surface on which to land.

30 In principle, it is possible that the plurality of box-channel units may be simply placed adjacent one another, possibly with the addition of a sealant between the adjacent units. However, it is preferred for the

adjacent box-channel units to be joined together. This may be achieved by means of an interlocking male/female joint along exterior side edges, a plurality of fastening elements passing through the side walls of adjacent units, or by a combination of the two.

Expediently, the cover layer may be bonded to the supporting sub-

layer of the box-channel units by an intermediate layer of double-sided adhesive tape. This prevents relative motion between the cover layer and the sub-layer, thus reducing wear on the underside of the cover layer, and 10 generally rendering the construction more stable.

Preferably, the cover layer is secured to the supporting sub-layer of boxchannel units by a plurality of fastener elements passing through the cover layer and into the material of the supporting sub-layer of box 15 channel units.

Permeability of the upper surface of the supporting sub-layer may be achieved by the provision of a plurality of apertures through the upper plates of the box-channel units and passing into the channels.

In one embodiment, heating or cooling pipes may be installed within a channel network provided by the box-channel units. In another embodiment, a sprinkler system may be installed within such a channel network and may be provided with suitable sprinkler heads mounted at a 25 position essentially flush with the surface of the turf.

In further embodiments, deflection layers may be interposed between the cover layer and the supporting sub-layer of box-channel units. Such layers may be employed to provide additional cushioning or 30 to modify the deflection characteristics of the surface according to the particular sport for which the surface is designed.

For most field sports, the upper surface will be generally flat and

level. However, in other embodiments it is possible to provide a contoured or curved surface by appropriate design and construction of the box-channel units.

If desired, the sports surface may be constructed to be Remountable so that it can be taken up and readily transported to an alternative site. In such an embodiment, it may be expedient to omit the fastening elements between adjacent box-channel units and even the 10 fasteners for securing the cover layer to the sub-layer.

According to another aspect of the invention, there is provided a method for constructing a sports surface comprising the following steps: laying a supporting sub-layer comprising a plurality of adjacent box 15 channel units; and laying a cover layer over the supporting sub-layer of boxchannel units.

Preferably the box-channel units are laid so as to provide a network of lateral channels within the sports surface.

If desired, piping connections may be installed between adjacent boxchannel units once the box-channel units are laid in position.

It may be desirable to join the adjacent box-channel units together 2s before any subsequent layer is laid.

In some embodiments, intermediate deflection layers may be laid on the supporting sub-layer before the cover layer is applied.

30 For rapidity in laying the surface, where a plurality of layers is to be laid over the box-channel units, said plurality of layers may be laid simultaneously.

In order to stabilize the construction, double sided adhesive tape may be inserted between layers as they are laid.

5 In order to ensure a rigid and stable construction, the layers may be fixedly attached together by a plurality of fastener elements passing through the layers into the supporting sub-layer.

Where it is desired to prevent surface water from passing entirely 10 through the sub-layer, a sealant may be applied along the gaps between adjacent box-channel units. The presence of such sealant will also tend to act as a separation layer, preventing migration of underlying soil and other materials upwardly through the structure.

15 Permeability of the upper surface of the sub-layer may be achieved during construction by the provision of a plurality of apertures passing through the top of the box-channel units and into the channels.

After the cover layer has been laid, it may be preferred to distribute 20 sand over the cover layer to a prescribed depth in order to improve stability of the pile and to modify the properties of the surface.

Alternatively, it may be desired to distribute a sand and rubber granule mixture over the cover layer to a prescribed depth.

25 For a better understanding of the invention, and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which: Figure 1 is a vertical crosssection through the sports surface, 30 according to an embodiment of the present invention; Figure 2 is a vertical cross-section through the sports surface, according to another embodiment of the present invention;

Figure 3 is a partial perspective view of the sports surface, according to an embodiment of the present invention; Figure 4 is a partial perspective view of box-channel units, according to an embodiment of the present invention; and 5 Figure 5 is a vertical cross-section showing, schematically, construction of the sports surface, according to one method of the present invention. For consistency, and to increase clarity, the same symbols are 10 used for the various components of the system throughout the drawings.

The nature of the construction is such that it readily accomplishes an underground channel network throughout the entire area of the sports surface. One advantage is that it allows for the use of any such channel 15 network in providing a drainage system for the sports field, with the

impermeable lower surface acting as a separation layer between the sports surface and the underlying ground, thereby making the construction suitable for laying on all nature of foundation materials with little or no ground preparation. A further advantage is that underground 20 piping systems, such as heating, cooling and sprinkler systems, may be installed below the cover layer within this channel network, again without requiring extensive ground construction.

In the embodiment according to Figure 1, the synthetic sports 25 surface is laid on unprepared ground or foundation material 10, and comprises: a supporting sub-layer 5, having an upper plate member 6 providing a generally smooth upper-surface, supporting webs 7 and a lower plate member 8, and is formed by a plurality of adjacent box channel units, which together provide a network of lateral channels 9. This 30 network affords drainage by water passing downwardly through perforations in the upper plate into the channels 9, and laterally through the network. A permeable artificial-turf-carpet layer 1, consisting of a

grass-like pile 3 woven into a mat 4, is fixedly attached to the upper plate members 6 of the box-channel units forming the supporting sub-layer 5.

Sand 2 is interspersed between the carpet piles to a prescribed depth.

5 In another embodiment, according to Figure 2, the synthetic sports surface comprises all of the features of Figure 1, including the ground 10; on which rests the supporting sub-layer 5 of box-channel units resting on the ground; and the artificial-turf-carpet layer 1. In this embodiment, additional deflection layers 11 and 12 are placed between the supporting 10 sub-layer 5 and the artificial-turf-carpet layer 1 in order to tailor the deflection, rebound and shock-absorption qualities of the surface to the requirements of individual sports, should the materials and design of the supporting sub-layer alone prove unable to produce the desired properties. In the embodiment according to Figure 3 there is shown a perspective view of a section of the sports surface, detailing: the artificial turf-carpet layer 1, with grass-like pile 2 and mat 4; part of a box-channel unit 22, with lower plate 8, supporting webs 7 and upper plate 6, creating 20 channels 9; a layer of double-sided adhesive tape 13 attaching the artificial-turf-carpet to the box-channel units; a plurality of holes 14 through the upper plate 6 into the channels 9, making the upper-surface permeable and allowing drainage directly into the channels; and a piping system 15 installed within the channels 9, providing connections to a 25 pump unit 16 and sprinkler heads 17.

The example embodiment of Figure 4 shows detail of a joint between two box-channel units 22, each comprising upper plate 6, supporting webs 7 and lower plate 8, with lateral channels 9. Along the 30 contiguous edges are provided interlocking male-/female- joints 18 and 19 respectively.

Figure 5 details schematically a method of construction for a sports floor, according to the following steps. Firstly, ground area 10 is made level; box-channel units 22 are laid on the ground and joined together by male-/female- joints 18 and 19; deflection layers 12 and then 11 are 5 unrolled onto the supporting sub-layer 5, followed by the artificial-turf-

carpet 1; the separate layers are fixedly attached to the supporting sub-

layer by a plurality of screws 20 through the multiple layers 1, 11, 12 and anchored in the supporting sub-layer 5; and sand is sprinkled from a device 21 over the attached artificial-turf-carpet to a prescribed depth.

10 One or both deflection layers 11 and 12 may be omitted in appropriate circumstances. These embodiments describe the invention in some detail; however, there are many aspects of the design that suggest alternative 15 solutions, as follows: Considering the artificial-turf-carpet, this can be fixedly attached to the supporting sub-layer by a number of means, two of which are: double sided adhesive tape; and, a plurality of screws through the turf carpet 20 layer into the supporting sub-layer. These can be used separately or in conjunction with one another, and have the advantage of being quick to use, with few associated hazards, as might be the case with some adhesives, for example. Obviously, the techniques may be applied regardless of the number of deflection layers, etc. by using the adhesive 2s tape between each layer and screws of appropriate length. Furthermore, if the artificial-turf-carpet is not already permeable then it can be made so by drilling or puncturing through the mat. If necessary, this can be done at the same time as perforation of the upper-surface of the box-channel units, thus saving time.

It should be noted that, in all of the Figures 1 to 3 and 5 and the statements in the preceding paragraph, it is feasible that the artificialturf

carpet layer be replaced by a different cover layer, such as short-pile carpet or a linoleum type surface covering, especially for indoor use.

When used indoors, it may be unnecessary for the hollow chambers within the box-channel units to be inter-connected, since there may be no 5 need to provide for drainage of surface water.

In a preferred embodiment, the supporting box-channel units are made from an extruded plastics material, preferably high density polyethylene although a number of other materials could be used. This 10 enables production, from a single process, of units with different deflection and shock-absorption properties tailored to the requirements of the specific sport in question. This has the advantage of reducing the need for any deflection layers, or removing them completely. It also has application to sports such as cricket, where it may be desirable for certain 15 areas of a pitch, in this case the crease and bowling areas, to have different properties to the rest of the pitch, as is the case with natural turf cricket grounds.

As shown, the box-channel units are generally flat and of uniform 20 thickness, with rectangular channels and flat upper- and lower- surfaces.

There are many possible designs for the shape of these channels, and indeed the box-channel units themselves. The channels need not be rectangular, but could be circular, triangular or any number of alternative shapes. The box-channel units, despite being shown here with a flat and 25 level upper surface, as would be necessary for a sports pitch, could in fact be made with shaped and contoured surfaces, for example, to recreate the undulations of a golf course. Along similar lines, the lower-surface need not be flat and level, but may incorporate sloped channels to provide better drainage, or indeed further channels and trenches as is required to 30 transport and contain the fluid flows, as is necessary to the particular situation.

In a preferred embodiment, the width of the individual channels should be less than half the width of a child's foot, such that no user would ever be supported by less than two of the supporting webs beneath their foot at any time. Alternatively, the upper-surface of the box-channel units 5 is designed so as to spread any concentrated loads across as wide an area as possible.

It will be understood that water passes vertically into the channels of the supporting sub-layer and is drained laterally through them. In order 10 to handle this water, it may be necessary to include further drainage devices, re-circulation devices, a reservoir, or any other mechanism for handling the flow. In the preferred embodiment, drainage is by gravity; however, it is feasible that there could be a pumping system in operation to increase drainage along the channels.

Although it is conceivable to omit entirely any jointing mechanism between the box-channel units, where provided, the joins between adjacent box-channel units, according to the above embodiments, are expediently made by interlocking male-/female- members. It is possible 20 that these joints be supplemented, or replaced, by screws, bolts, a combination of the two, or any other conceivable joining method between adjacent units. Further regarding the joints between box-channel units, it is also possible to apply a sealant to the joints to prevent unwanted fluid transport through the supporting sub-layer. In this case, a fully joined and 25 sealed supporting sub-layer not only provides a drainage network throughout the entire sports surface, but has the added advantage of the lower-surface acting as a separation layer between the artificial turf and any underlying migrating material.

30 As described, there is provided the means for incorporating a piping network within the channels of the supporting sub-layer. These pipes could have a number of uses, such as for heating or cooling and sprinkler

systems, amongst others, and have the advantage of being relatively cheap and easy to install and maintain by comparison to traditional methods. Such systems will likely incorporate devices such as pumps or sprinkler heads, either within or beneath the sports surface, or around its 5 periphery.

Following the modern trend of multi-functional sports arenas, it is likely that a desirable feature of the sports surface would be transportability. In one possible embodiment, the entire sports surface 10 could be constructed on a single (or series of) mobile plafform(s) and transported in and out of a stadium as required. The light-weight nature of the structure makes this surface an ideal candidate for such a scheme.

Similarly, the sports surface need not undergo the entire construction on-

site, but could be manufactured in sections off-site and transported to the 15 desired location, requiring only a minimal amount of connection work in order to join together sections at the destination. Such a scheme might be ideal for seasonal use of a sports area, where the sports surface could be installed during a sports season and removed for the months in between. Again, the simple construction of this invention makes such a 20 scheme feasible.

Claims

CLAIMS:

1. A synthetic sports surface comprising: a supporting sub-layer, having a generally smooth upper-surface, formed by a plurality of 5 adjacent boxchannel units; and a cover layer fixedly attached over said supporting sub-layer.

2. A synthetic sports surface according to claim 1, wherein said box channel units provide a network of lateral channels, affording lateral drainage of water passing downwardly into the channels; 10

3. A synthetic sports surface according to claim 2, wherein the upper surface of the supporting sub-layer of box-channel units is made permeable by a plurality of holes through the top of the box-channel units into the channels.

4. A synthetic sports surface according to claim 2 or 3, wherein 15 heating/ cooling pipes are installed within said channel network.

5. A synthetic sports surface according to any one of claims 2 to 4, wherein a sprinkler system is installed within said channel network, having suitable sprinkler heads installed in the surface.

6. A synthetic sports surface according to any one of claims 1 to 5, 20 wherein the cover layer is bonded to the supporting sub-layer of boxchannel units by an intermediate layer of double-sided adhesive tape.

7. A synthetic sports surface according to any one of claims 1 to 6, wherein the cover layer is fixed to the supporting sub-layer of box 25 channel units by a plurality of fastener elements passing through the cover layer and into the material of the supporting sub-layer of boxchannel units.

8. A synthetic sports surface according to any one of claims 1 to 7, wherein said cover layer is made from a linoleum type material.

30

9. A synthetic sports surface according to any one of claims 1 to 7, wherein said cover layer is a permeable artificial-turf-carpet layer.

10. A synthetic sports surface according to claim 9, wherein sand is interspersed amongst the pile of said artificial-turf-carpet, to a prescribed depth.

11. A synthetic sports surface according to claim 9, wherein a mixture 5 of rubber granules and sand is interspersed amongst the pile of said artificial-turf-carpet, to a prescribed depth.

12. A synthetic sports surface according to any one of claims 1 to 11, wherein the box-channel units are of synthetic plastics-material.

13. A synthetic sports surface according to any one of claims 1 to 12, 10 wherein the adjacent box-channel units are joined together.

14. A synthetic sports surface according to claim 13, wherein the box channel units are joined by means of interlocking male-/female joint sections along exterior side edges.

15. A synthetic sports surface according to claim 13 or 14, wherein the 15 box-channel units are joined by a plurality of fasteners through adjacent box-channel units.

16. A synthetic sports surface according to claim 15, wherein the box channel units are joined by a plurality of screws or bolts through adjacent box-channel units.

20

17. A synthetic sports surface according to any one of claims 1 to 16, wherein deflection layers are interposed between the cover layer and the supporting sub-layer of box-channel units.

18. A synthetic sports surface according to any one of claims 1 to 17, wherein the upper-surface of the sports surface is generally flat and 25 level.

19. A synthetic sports surface according to any one of claims 1 to 18, wherein the sports surface is Remountable.

20. A method for constructing a sports surface comprising the following 30 steps: laying a supporting sub-layer comprising a plurality of adjacent box-channel units; and laying a cover layer on the supporting sub-layer of box-channel units.

21. A method for constructing a sports floor according to claim 20, wherein the box-channel units are laid so as to provide a network of lateral channels

22. A method for constructing a sports surface according to claim 20 or 5 21, wherein piping connections between adjacent boxchannel units are made once the box-channel units are laid in position.

23. A method for constructing a sports surface according to any one of claims 20 to 22, wherein adjacent box-channel units are joined before any subsequent layer is laid.

10

24. A method for constructing a sports surface according to any one of claims 20 to 23, wherein intermediate deflection layers are laid on the supporting sub-layer before the cover layer is laid.

25. A method for constructing a sports surface according to any one of claims 20 to 24, wherein the layers above the supporting sub-layer 15 of box-channel units are laid simultaneously.

26. A method for constructing a sports surface according to any one of claims 20 to 25, wherein double-sided adhesive tape is inserted between layers as they are laid.

27. A method for constructing a sports surface according to any one of 20 claims 20 to 26, wherein the layers are fixedly attached to one another by a plurality of fastener elements passing through the layers into the supporting sub-layer once the cover layer is laid.

28. A method for constructing a sports surface according to any one of claims 20 to 27, wherein sealant is applied along the gaps between 2s adjacent box-channel units before subsequent layers are laid.

29. A method for constructing a sports surface according to any one of claims 20 to 28, wherein the upper-surface of the supporting sub layer is rendered permeable during construction, by providing a plurality of holes through the top plates of the box-channel units into 30 the channels.

30. A method for constructing a sports surface according to any one of claims 20 to 29, wherein once the layers are completed, sand is distributed over the cover layer to a prescribed depth.

31. A method for constructing a sports surface according to any one of 5 claims 20 to 29, wherein once the layers are completed, a mixture of rubber granules and sand is distributed over the cover layer to a prescribed depth.

32. A kit of parts for constructing a sports surface according to claim 1, 10 comprising a plurality of box-channel units; and a supply of a cover layer material to be laid over said box-channel units.

33. A sports surface substantially as hereinbefore described, with reference to the accompanying drawings.

15

34. A method for constructing a sports surface substantially as hereinbefore described, with reference to the accompanying drawings.

35. A kit of parts for constructing a sports surface substantially as hereinbefore described, with reference to the accompanying 20 drawings.