Technical Field of the Invention

The present invention relates to a golf course bunker and to a method of constructing a golf course bunker. More particularly, the present invention relates to a golf course bunker comprising an improved liner and to a method of constructing a golf course bunker comprising an improved liner.

Background to the Invention

The maintenance of a golf course is crucial to the golfer and as such to the success of a golf course in general. The level of maintenance is directly related to many issues, but it is the quality of the playing surfaces and the appearance of the golf course that matter most to the average golfer. One of the most demanding areas in terms of the expense, time, effort and labour is the maintenance of golf course bunkers. Golf bunkers are critical to the strategy and appearance of most golf courses and this has been the case for hundreds of years. Bunkers typically comprise areas with a native soil base and/or face, the base and, in certain instances the face, covered with a layer of sand. Nevertheless, maintaining bunkers can involve significant and often disproportionate expense. This is due to a combination of factors: heavy rain which washes elements of the sand layer of face away, erosion of the face, subsidence, damage to the face caused by golf clubs as well as golf balls, damage caused by animals, wear and tear caused by machinery in or around the bunker and contamination of the bunker sand by the underlying soil. Drainage of bunkers can also be compromised when fine particles of soil contaminate the bunker sand, and as a result, the natural free drainage properties of sand can be lost. Bunkers filled with water that does not drain away id a significant problem for those tasked with maintaining golf courses.

Some of these issues can be alleviated by providing a bunker liner between the sand of the bunker and the underlying surface which is usually soil. A very simple example of such a liner would be a water permeable fabric provided on the soil before filling the bunker with sand. Such liners are unsatisfactory as they are prone to damage by golfers, have a limited lifespan and are readily deformed by soil movement, particularly in where the soil is liable to freeze. These fabric liners also have to be joined, and this is normally done by lapping the liners and driving pegs through. This has proved to be an unsatisfactory method. Gaps can be easily left and freeze thaw action tends to lift pegs out of the ground, destroying the joint. When this happens the whole bunker liner fabric has to be replaced. Sometimes the ground is too firm or stony to use pegs, and instead jointing tape and glues are used. This form of jointing has proved to be unreliable. In place of fabric liners, use of permeable layers comprising cement or bonded polymer granules have been used. These tend to be more robust than fabric layer and thus last longer as well as helping a bunker maintain a desired shape. Nevertheless, such liners are considerably more expensive to install, not least because they require specialist installation personnel rather than being installed by general purpose course maintenance staff. Additionally, if such a liner is damaged or if the bunker shape is to be adjusted, it is necessary to remove and replace the full liner.

More recently, porous polymer matting has been used as bunker liners. Such matting can be dispensed from a roll, cut to a suitable size and bonded together edge to edge so as to cover a bunker base. Such matting liners are more robust than fabric liners and simpler to install than cement or polymer granule based liners. One light weight example of a porous polymer mat comprises an irregular web of polymer filaments. Such mats are also known as miners moss due to their suitability for use in trapping gold or mineral particles when used in a sluice.

Whilst miners moss provides a practical bunker liner with good vertical water permeability, it is not without drawbacks. Firstly, a significant proportion of the apertures within and between coils in miners moss are typically large enough to permit at least some penetration of the liner both by fine and medium sized sand grains and soil particles. This impacts on a key benefit of using the liner. Whilst the soil/sand penetration can be mitigated by using a mat with relatively high coil density and/or relatively tightly twisted coils, this has the drawback of reducing the frictional interaction with loose sand grains. As such steeper portions of the bunker are prone to sand slides exposing the liner. Increasing the overall density would also reduce the drainage performance of the liner both in the vertical plane (through the liner) and in the horizontal plane (along and within the liner). Increasing the overall density would also make the product heavier and more difficult to install, and make it more expensive to manufacture, transport and buy.

Another problem with the current use of miners moss is that because the apertures are uniformly wide through the whole depth of the profile, any fine to medium sized sand or soils can pass straight through onto the surface of the ground underneath the liner. Over a period of months or just a few years this can cause the liner to rise within the sand profile and in extreme circumstances, come to the surface. When this happens there is a potential safety hazard as golf clubs can become snagged in the liner and potentially cause wrist damage to the golfer.

It is therefore an object of the present invention to provide a golf course bunker and associated method of construction that at least partially overcomes or alleviates the above issues.

Summary of the Invention

According to a first aspect of the present invention there is provided a golf course bunker comprising: a bunker liner provided over a base, , and a sand layer provided over the bunker liner wherein the bunker liner comprises a mat formed from an irregular web of polymer filaments, the mat having a higher density surface and a lower density surface, the mat orientated such that the higher density surface is provided against the base and the lower density surface is provided below the overlying sand.

The provision of the mat formed from an irregular web of polymer filaments provides for an easy to install, bunker liner. Typically, mats formed from irregular coils of polymer fibre have substantially constant density and thus opposing surfaces of the matt have essentially similar properties, however, in the present invention the mat has a lower density (relatively open) upper surface and a higher density (relatively closed) lower surface. Both surfaces provide for good water permeability. The higher density surface provides relatively small apertures and hence substantially reduces penetration of the liner by sand grains or soil particles. The lower density surface has relatively large apertures and hence improves the frictional interaction between the liner and the overlying sand, so as to help retain sand on steeper sloped areas.

The profile of the mat may vary continuously from a lower density surface to the higher density surface. In other embodiments, the profile of the mat comprises a lower density zone at the lower density surface and a higher density zone at the higher density surface. In such embodiments, the lower density zone may be thicker than the higher density zone. For example, the thickness of the lower density zone may be say 2 to 6 times greater than the thickness of the higher density zone. In one such example, the lower density zone may have a thickness of, say, 4 times greater than the higher density zone.

In one embodiment, both the lower density zone and the higher density zone may provide approximately equal contribution to the overall weight of the mat. In such cases the ratio of the relative zone thicknesses may be the inverse of the relative zone densities.

In some such embodiments, there may be a transition zone separating the two layers. The transition zone may be relatively narrow in comparison to the lower density zone and the higher density zone.

The mat may have an overall weight in the range of, say, 2 to 6 Kg per square meter or, say, 3 to 5 Kg per square meter. In one embodiment the mat may have an overall weight of the order of, say, 4 Kg per square meter.

The mat filaments may have a thickness in the range of, say, 0.5mm to 1.5mm. In one embodiment, the filaments may have a thickness of the order of, say, 1mm.

The matt may have an overall thickness in the range of, say, 5mm to 20mm or say, 10mm to 15mm. In one embodiment, the mat may have an overall thickness of the order of, say, 12mm. The higher density zone may have a thickness in the range of, say, 0.5mm to 6mm or say, 1mm to 4mm. In one embodiment, the higher density zone may have an overall thickness of the order of, say, 2.5mm. The lower density zone may have a thickness in the range of, say, 5mm to 15mm or say, 8mm to 12mm. In one embodiment, the lower density zone may have an overall thickness of the order of, say, 9.5mm. The mat may be formed from any suitable polymer material. Examples of suitable material include but are not limited to recycled PVC. In one embodiment, the mat may be formed from - 60% PVC, with the remaining -40% comprised of additional additives as required or as desired.

In some embodiments, the mat may comprise two or more mat sections bonded together edge to edge. In this manner a liner covering a full bunker base can be formed from a number of smaller sections. In such embodiments the mat sections may be bonded together by use of a suitable method. In such embodiments, suitable methods include (but are not restricted to) the use of solvents to temporarily melt the polymer coils at the interface of two separate sections, and allow a joint to form. This is also known as a weld.

The mat comprising the mat may be shaped to correspond to the bunker base. In some embodiments, this can be achieved by cutting the mat or mat sections to correspond to the bunker base. In some embodiments, the exterior edges of the mat may be turf capped.

In some embodiments, the mat may be secured to the soil. The mat may be secured at one or more suitable points distributed across the bunker base. In some embodiments, the mat may be additionally or alternatively secured at one or more suitable points distributed around the edge of the bunker base. In embodiments, where the liner is formed form multiple mat sections, the mat may be secured at points corresponding to bonds between mats. The mat may be secured by use of any suitable fixture. Examples of suitable fixtures include but are not limited to staples, pegs or the like.

The bunker base may be a soil base or may be defined by any other suitable material laid over the soil. The base may be shaped to a desired profile. The shaping may be carried out by any suitable tools or machinery.

In one embodiment, the mat is impregnated with granular particles. The impregnation may take place before the overlying sand is provided. Impregnation may be achieved by brushing granular material into the mat. The impregnation by granular particles further reduces penetration of the liner by sand grains or soil particles. Additionally, the granular material also provides support in the less dense upper layer of the mat and prevents the polymer filaments from being compressed under load from above. In one embodiment, the granular particles may impregnate only the lower density zone.

The granular material may comprise any suitable inert and chemically stable material. Suitable granular materials may be derived from natural rocks and stones, that have been eroded either naturally by the forces of nature or manufactured by man-made crushing machinery. Some such materials are commonly referred to as gravel. In other embodiments, the granular material may comprise synthetic materials such as rubber crumb, recycled glass beads or similar.

The average particle size in the granular material may be larger than the average particle size of the overlying bunker sand. In one embodiment, the granular material is selected such that the average particle size is in the range of say, 3 to 7 times greater than the average particle size of the overlying bunker sand. For example, given a bunker sand with an average particle size of around 0.3mm, the granular material should have a average particle size not greater than say 2mm. Due to practical matters, it is often difficult to obtain pure granular material where all particles fall within a very narrow size range. Nevertheless, in this example the granular material may have a particle size range of between 1mm and 3mm. ins such examples, the majority of grains may be of the order of 2mm.

In one embodiment, the mat may be impregnated by a weight of granular material the range of 5kg to 10kg per square meter of mat. In one embodiment, the mat may be impregnated by a weight of granular material of the order of, say, 7kg per square meter of mat. In one embodiment, the mat may be impregnated by say 0.0025 and 0.0050 cubic meters of granular material per square meter. In one embodiment, the mat may be impregnated by a volume of granular material of the order of, say, 0.0035 cubic metres per square meter of mat.

In some embodiments, a binding agent may be applied to the granular particle impregnated mat. The binding agent may be a resin. Suitable resins include water based or acrylic based resins. In this manner, the binding agent can act to secure the granular particles within the mat. The amount of binding agent applied may be selected to adequately secure the granular particles without causing significant impairment to permeability.

According to a second aspect of the present invention there is provided a bunker liner in the form of a mat, the mat comprising: a mat formed from an irregular web of polymer filaments, the mat having a higher density surface and a lower density surface.

The bunker liner of the second aspect of the present invention may incorporate any or all features of the bunker of the first aspect of the present invention a desired or as appropriate.

According to a third aspect of the present invention, there is provided a method of constructing a golf course bunker comprising the steps of: providing a bunker base in a desired shape; providing a mat formed from a mat formed from an irregular web of polymer filaments, the mat having a higher density surface and a lower density surface; laying the mat over the base, the mat orientated such that the higher density surface is provided against the base; and applying a layer of sand over the lower density surface of the mat.

The method of the third aspect of the present invention may incorporate any or all features of the first two aspects of the present invention as desired or as appropriate.

The method may include digging and/or shaping the bunker base to a desired shape. The method may include providing one or more drains below the bunker base.

The method may include dispensing the mat from a roll. The method may include bonding together two or more mat sections edge to edge. The method may include cutting the mat or mat sections to correspond to the bunker base. The binding and/or cutting may take place prior to brushing granular material into the mat.

The method may include securing the mat to the soil. The mat may be secured at: one or more suitable points distributed across the bunker base; and/or one or more suitable points distributed around the edge of the bunker base. Where the mat comprises mat sections bonded together, the mat sections may be secured to the soil at points corresponding to bonds between mats.

In some examples, the edges of the mat or mat sections at may be overlapped by turf surrounding the bunker.

In one embodiment, the method may comprise impregnating the mat with granular particles prior to applying the overlying sand. The impregnation may be achieved by brushing granular material into the mat.

In one embodiment, the method may comprise application of a binding agent to the granular particle impregnated mat. The binding agent may be applied by spraying.

According to a fourth aspect of the present invention there is provided a golf course bunker comprising: a bunker liner provided over a soil base, and a sand layer provided over the bunker liner wherein the bunker liner comprises a mat formed from an irregular web of polymer filaments of substantially constant density, the web being impregnated with gravel particles.

The bunker of the fourth aspect of the present invention may incorporate any or all features of the previous aspects of the invention, as desired or as appropriate.

The provision of the granular material impregnated mat formed from an irregular web of polymer filaments of substantially constant density thus provides for an easy to install, bunker liner with good water permeability. The granular material impregnation substantially reduces penetration of the liner by sand grains or solid particles. It additionally improves the frictional interaction between the liner and the overlying sand, so as to help retain sand on steeper sloped areas and also provides support that prevents the polymer filaments from being compressed under load from above.

According to a fifth aspect of the present invention there is provided a bunker liner in the form of a mat, the mat comprising: an irregular web of polymer filaments of substantially constant density impregnated with granular material particles. The bunker liner of the fifth aspect of the present invention may incorporate any or all features of the previous aspects of the invention, as desired or as appropriate.

According to a sixth aspect of the present invention, there is provided a method of constructing a golf course bunker comprising the steps of: providing a soil base in a desired shape; providing a mat from an irregular web of polymer filaments of substantially constant density; laying the mat over the base; brushing granular material into the mat so as to form a granular material impregnated irregular web of polymer filaments; and applying a layer of sand over the granular material impregnated irregular web of polymer filaments.

The method of the sixth aspect of the present invention may incorporate any or all features of the previous aspects of the invention, as desired or as appropriate.

Detailed Description of the Invention

In order that the invention may be more clearly understood one or more embodiments thereof will now be described, by way of example only, with reference to the accompanying drawings, of which:

Figure 1 shows a schematic cross-section of a golf course bunker according to the present invention;

Figure 2 shows a schematic cross-section of a mat used as a liner for a golf course bunker according to the present invention, (a) without granular material impregnation, (b) with granular material impregnation, and (c) installed in a bunker;

Figure 3 is a schematic overhead view of a golf course bunker according to the present invention where the liner is constructed from multiple mat sections bonded together; and

Figure 4 is a schematic cross-section illustrating the bonding together of two mat sections from a mat of the type shown in figure 2 prior to granular material impregnation; and Figure 5 shows a schematic cross-section of a substantially constant density mat used as a liner for a golf course bunker according to the present invention, (a) without gravel impregnation, (b) with gravel impregnation, and (c) installed in a bunker.

Turning now to figure 1, a schematic illustration of a golf course bunker 1 according to the present invention is shown. The bunker 1 comprises a shaped depression in the soil surrounded by turf grass 5. The bunker 1 comprises a base 2 formed from the local soil and a bunker liner 4 provided over the base 2. The base 2 may in some examples include one or more drains (not shown). A layer of sand 3 overlies the liner 4 to provide a playing surface. The liner 4 allows water to permeate through the liner 4 into the soil and drain away but provides a barrier to mixing of the soil and sand particles 3.

As is illustrated in figure 2, in the present invention, the liner 4 is formed from a mat 10 comprising an irregular web of continuous polymer filaments 11. Such mats 10 are also known as miners moss.

Turning to figure 2 the liner 4 comprises a mat 10 having surfaces of two different densities. The profile of the mat 10 comprises a lower density zone 18 at the lower density surface and a higher density zone 19 at the higher density surface. As shown, the lower density zone is thicker than the higher density zone but the higher density zone 19 has more and/or tighter coils per unit volume than the lower density zone 18 and consequently smaller voids than the lower density zone 18. The mat 10 is installed with the lower density zone 18 uppermost and the higher density zone 19 lowermost. The higher density zone 19 provides a relatively more effective direct barrier to soil/sand penetration as a result of the smaller voids than the lower density zone 18. The larger/looser coils and/or larger voids of the lower density zone beneficially create a larger frictional interaction between the sand 3 and the liner 10. This helps to retain sand 3 in position on more steeply sloped areas.

In one practical example, the mat 10 might be formed from PVC filaments (or predominantly PVC filaments) with a thickness of the order of 1mm. The mat may have an overall thickness of the order of say 12mm, with the higher density zone 19 having a thickness of the order of 2.5mm and the lower density zone 18 having a thickness of the order of say 9.5mm. The overall weight per square meter of the mat 10 may be of the order of 4kg per square meter. Typically, the relative densities of higher density zone 19 and lower density zone 18 are selected such that each layer 18, 19 has a similar weight per square meter.

As is illustrated in figure 2 the mat 10 can be impregnated with granular material 15, for instance by brushing the granular material 15 into the mat. The granular material particles 15 fill voids 12 between the polymer filaments 11. In this manner, the granular material provides a significantly greater impediment to the penetration of the liner 4 by soil or sand particles than the mat 10 alone. The granular material particles 15 do not significantly impede water from percolating through the liner 4. The granular material also provides support in the less dense upper layer of the mat and prevents the polymer filaments 11 from being compressed under load from above.

The size of granular material particles 15 used with mat 10 may be selected depending upon the expected range of void sizes 12 and/or the expected bunker sand particle size. In one practical example, granular material particles of with an average diameter of up to 7 times the average diameter of the bunker sand 3 would be selected. Based on a typical bunker sand having an average particles size of 0.3mm, a suitable granular material might have an average particle size of the order of 2mm.

In order to construct the bunker 1, the bunker base 2 is shaped from the local soil and any necessary drainage is installed. Subsequently, the mat 10 is laid on the base 2, the higher density zone 19 is lowermost, and the lower density zone 18 is uppermost. If necessary, the mat 10 can be secured to the soil base 2 by use of one or more pegs or staples (not shown) at one or more locations.

Once the mat is in position, granular material particles 15 are poured over the mat 10. As an example, one might add, say 7kg of granular material particles 15 per square meter of mat. The granular material particles 15 are then brushed into the mat, so as to fill voids 12.

Optionally, a water or acrylic based resin may be applied to the to the granular particle 15 impregnated mat 10 as a binding agent. The binding agent application may be by way of spraying or any other suitable technique. Suitable application of binding agent can help secure the granular particles 15 within mat 10 without impairing water permeability.

Where the bunker base 2 has a smaller area than the available mat 10, the mat 10 may be cut to match the area of the bunker base 2. More typically, the bunker base 2 is larger than any single section of mat 10 available. In such cases, multiple mat sections 10 may be bonded together edge to edge as shown in figure 3. In such cases, the bonds 4 may be formed by use of a bonding agent 6. Figure 4, further illustrates, in cross-section, how mats 10, can be bonded by use of a bonding agent 6, prior to granular material impregnation. In one practical example, the bonding agent may be a solvent capable of forming a PVC weld.

Turning to figure 5, an alternative embodiment of the liner 4 comprises a mat 10 of substantially constant density. In one practical example, the mat 20 might be formed from PVC filaments (or predominantly PVC filaments) with a thickness of the order of 1mm. The mat 20 may have an overall thickness of the order of say 12mm. The overall weight per square meter of the mat 20 may be of the order of 4kg per square meter.

As is illustrated in figure 5 the mat 20 can be impregnated with granular material 25, for instance by brushing the granular material 25 into the mat. The granular material 25 fill voids 22 between the polymer filaments 21. In this manner, the granular material 25 provides a significantly greater impediment to the penetration of the liner 4 by soil or sand particles than the mat 20 alone. The granular material particles 25 do not significantly impede water from percolating through the liner 4. The granular material also provides support that prevents the polymer filaments 21 from being compressed under load from above.

The size of granular material particles 25 used with mat 20 may be selected depending upon the expected range of void sizes 22 and/or the expected bunker sand particle size. In one practical example, granular material particles of with an average diameter of up to 7 times the average diameter of the bunker sand 3 would be selected. Based on a typical bunker sand having an average particles size of 0.3mm, a suitable granular material might have an average particle size of the order of 2mm. The alternative embodiment of the liner 4 described in figure 5 may be formed by the same technique as described for the first embodiment, with the exception of the need to orientate the mat in terms of differing density zones.

The one or more embodiments are described above by way of example only. Many variations are possible without departing from the scope of protection afforded by the appended claims.