GB2311730A - Synthetic turf cricket pitch - Google Patents

Abstract

A cricket pitch is made by excavating the pitch area, lining the excavation with a geotextile 28, laying a base layer of stone 12, laying a layer of geotextile material 16, filling the trench with hard porous material 14, applying an optional layer shock pad layer 20, and covering it all with a synthetic turf material. Optionally, an area round the stumps may be hollowed out, lined with a geotextile material and filled with clay so that the stumps may be more easily accommodated.

Description

SYNTHETIC TURF CRICKET PITCH The present invention relates to synthetic or artificial sports surfaces and more particularly to synthetic turf cricket pitches.

In known synthetic turf cricket pitches a synthetic turf material is laid either directly onto the earth or laid onto a shock pad which is laid onto the earth.

In a further known design the earth is dug out to a predetermined depth and a specifically designed foundation layer is laid. The synthetic turf and, if used, the shock pad are then laid on top of the foundation layer.

The important area for a cricket pitch is where the ball bounces and this is in the length between the wickets which are 20 Metres apart. The remainder of the pitch which can be a further 10 Metres comprising run up areas at each end of the pitch are less important from the point of view of ball bounce characteristics.

In the present invention the inventor has discovered that for a pitch to have a desired bounce characteristic it is beneficial to use a two layered base structure comprising a first layer of stone on top of which is laid a layer of unbound mineral with interlocking or bonding properties (hard porous).

The synthetic turf and, if required, shock pad are laid on top of this surface.

The advantage of this two layered base structure is that the stone forms a rigid base structure through which water drains freely but this is not suitable to give the required bounce characteristics required for a cricket pitch. By placing a layer of hard porous material on top of the stone, the required bounce characteristics can be achieved.

The present invention therefore uses a two layered structure but in addition, in order to preserve the bounce characteristics of the pitch over a long lifetime, a geotextile is positioned between the stone and the hard porous material. This prevents migration of the stone into the hard porous material and maintains the original bounce characteristics. Also a geotextile is positioned underneath the stone and up the sides of the excavation to prevent erosion and contamination from outside source.

The inventor has also realised that the geotextile separating the two layers is only necessary over the length of the pitch where the ball bounces since the bounce characteristic is only required to be maintained over this portion of the pitch.

A further problem is the desire to use conventional stumps which have to be inserted into the top surface of the pitch. The length of the point on each stump is approximately 75 mm long and these stumps are usually inserted by being pressed through the upper surface of the synthetic turf, through the shock pad (if present) and into the hard porous layer.

If the geotextile in the stump area is continuous and is within a depth of 75 mm or even possibly 90 mm from the surface then it may be pierced by the stumps when inserted or provide access to worms. If this occurs then the stone and hard porous will mix in this area, thereby causing a premature deterioration in the pitch.

In the present invention it is proposed to include, in the stump area a separate vertical pitch portion which is also contained within a separate geotextile. This portion can be used to hold the stumps in a firm manner in, for example, a clay soil. The stumps will therefore be held in a medium which is more suitable for this purpose, it being remembered that stumps are continuously being removed either at the end of each game or, more forcibly, when struck with the ball during bowling, stumpings or run outs.

Such stump areas are therefore subject to substantial wear and for this reason the use of a further geotextile is advantageous in preventing erosion into the stone and hard porous layers.

It is therefore an object of the present invention to provide an improved synthetic turf cricket pitch in which the bounce characteristic is selectable and maintained substantially constant during the life of the pitch.

It is also an object to provide a synthetic cricket pitch in which the stump area is isolated from the rest of the pitch such that the stumps may be held in a medium different from the main pitch base layers.

A similar construction can be used for a practise pitch. In this case only one set of stumps is required and the length of the pitch may be substantially less than the length of a normal pitch - for example, 11 metres long. There may be no requirement for a run up area at one or both ends.

The present invention provides a synthetic grass cricket pitch comprising a portion where the ball is intended to pitch and at least one end portion including a first base layer comprising stone chippings laid into an excavation, a second base layer laid on top of the first layer and comprising a hard porous medium and a third layer comprising a synthetic turf material laid on top of the second layer and in which over the length of the portion of the pitch where the ball is intended to pitch the first and second layers are separated by a first geotextile and in which a second geotextile material is laid underneath and up the sides of the excavation over the entire length of the pitch.

Preferably the pitch comprises two end portion with the portion where the ball is intended to bounce centrally positioned therebetween.

Preferably a shock pad is positioned between the second layer and the synthetic turf material.

In a preferred embodiment, at each stump position a separate geotextile lined vertical section is provided into which, in use, the stumps are insertable.

Preferably the separate geotextile lined vertical section extends only across a portion of the width of the pitch.

Preferably the separate geotextile lined vertical section is filled with clay for better retention of the stumps.

The present invention provides a method of constructing a synthetic cricket pitch comprising the steps of: i. excavating an elongate trench in a soil surface; ii. laying a first geotextile layer in the bottom and sides of the trench to isolate the structure from the surrounding soil; iii. filling the trench to a partial depth with a layer of stone; iv. compacting the stone; v. in the area of the trench where the ball is intended to bounce in front of a stump position, covering the stone layer with a second geotextile layer; vi. filling the trench with a further layer of hard porous material; vii. compacting the hard porous material; viii. covering the hard porous material with a synthetic turf material; and ix. securing the synthetic turf material.

Preferably the area where the ball is intended to bounce comprises a central portion of a pitch between two stump positions.

Preferably following step vii. the method further comprises i. removal at each stump position of a vertical section to form a hole; ii. lining the hole formed by the removal of the vertical section with a third geotextile to form a vertical box; iii. filling the box with a medium suitable for retention of the stumps.

Preferably the medium is clay.

Also preferably prior to step vii. a shock pad is placed on the hard porous material.

Embodiments of the present invention will now be described, by way of example, with reference to the accompanying drawings in which: Figure 1 shows a longitudinal cross-section of a synthetic cricket pitch according to the present invention, and Figure 2 shows the pitch of Figure 1 in cross-section across the line of the stumps.

With reference now to Figure 1 in a preferred embodiment, the synthetic pitch 10 comprises a geotextile lining 28 to an excavation of l0Omm, a first layer 12 of angular stone, particle size of no greater than 10 mm and a second layer 14 of hard porous material. These two aggregate layers are separated in the distance between the stump positions by a further geotextile layer 16.

A layer of synthetic turf 18 is laid on top of the layer 14 and in a particular embodiment a shock pad layer 20 is interposed between the hard porous layer 14 and the synthetic turf 18.

In a preferred embodiment the thickness of the first layer is 50 mm and that the second layer is also 50 mm. The length of the complete structure is approximately 30 Metres and the distance between the stumps is 20 Metres, leaving a length of approximately 5 Metres at each end of the playing area behind the stumps.

The important part of the pitch for bounce characteristics is the area where the ball bounces. The first layer of stone and the second layer of hard porous gives the desired bounce characteristics. The interposed geotextile layer ensures that the stone and hard porous material never mix thereby ensuring that the bounce characteristic remains constant over an extended period.

At the area of each of the stumps a vertical sectional volume 22,24 is present. This comprises a geotextile line "box" shown in Figure 2 to be slightly wider than the width of the stumps.

In a preferred embodiment the box is approximately 350 mm wide, the width of the geotextile 16 is no less than 2.00 Metres wide and the width of the trench structure 2.40 Metres wide. The synthetic turf is preferably 2.74 Metres wide and the turf is fixed at intervals along each edge by suitable pins 180. If used the shock pad is preferably 2.44 Metres wide thereby providing a small overlap as shown.

The construction of the pitch is as follows. On a selected site a trench 24 is dug out of the earth. The trench 24 is preferably lined with a first geotextile 28 to prevent any ingress of the soil or worms into the construction. The first layer of stone 12 is laid in the trench to a depth of 50 mm. The stone layer is rolled or otherwise suitably firmed to provide a firm base. The stone is laid over the entire length and width of the trench 26.

The geotextile layer 16 is then laid only over the centre portion of the pitch in the area it is intended the ball will bounce when bowled to the batsman. The top hard porous layer 14 is then laid over the entire length and width of the trench and this layer is also compacted.

At each end at the stump position the two layers 12,14 are then dug out to provide the stump boxes 22,24. these are lined with geotextile and then this is filled with clay and this is then compacted.

The entire area is then covered with the shock pad 20 and then the artificial turf layer 18 to form the top surface of the pitch.

At each stump position three holes are then provided for the stumps indicated by dotted lines 30, the points of which will be held by the clay soil 32 in boxes 22,24.

The constant removal of the stumps 30 cannot therefore contaminate the layers 12,14. Neither can the drainage through the stump holes when the pitch is not in use. Therefore the pitch maintains its correct bounce characteristics and flatness, particularly in the areas just in front of the stumps which is the most important area for the batsman and bowler.

With reference to Figure 1, if a practice pitch is required then the pitch may comprise only half the structure, for example to the right of line A-A. In this case the geotextile 28 is fitted into the shorter box terminating at A-A and is preferably fitted up the side of the excavation box.

Since a run up is not required at the right hand end, the box can be terminated at line B-B, i.e. in front of the stumps. Again the geotextile layer 28 will be fitted into the side of the box. The stumps may then be fitted behind (i.e. to the right) of line B-B. The stumps will therefore be held in the normal earth surface and there is no requirement for a box to isolate the stump area. The area of the pitch where the ball bounces will still comprise the two layers of stone and hard porous separated by geotextile 16 and isolated by geotextile 28 from the surrounding earth, thereby preventing worm intrusion and mixing of the layers either with themselves or with the surrounding soil.

In this case the bowler will run up either on the natural grass surface or possibly on a lower grade artificial turf structure.

Claims (13)

1. A synthetic grass cricket pitch comprising a portion where the ball is intended to pitch and at least one end portion including a first base layer comprising stone chippings laid into an excavation, a second base layer laid on top of the first layer and comprising a hard porous medium and a third layer comprising a synthetic turf material laid on top of the second layer and in which over the length of the central portion of the pitch between the stumps the first and second layers are separated by a second geotextile in which a first geotextile material is laid underneath the first layer and up the sides of the excavation over the entire length of the pitch.

2. A synthetic grass cricket pitch as claimed in claim 1 and comprising two end portions with the portion where the ball is intended to bounce being positioned therebetween.

3. A synthetic grass cricket pitch as claimed in claim 2 in which a shock pad is positioned between the second layer and the synthetic turf material.

4. A synthetic grass cricket pitch as in any one of claims 1 to 3 in which at each stump position a separate geotextile lined vertical section is provided into which, in use, the stumps are insertable.

5. A synthetic grass cricket pitch as claimed in claim 4 in which the separate geotextile lined vertical section extends only across a portion of the width of the pitch.

6. A synthetic grass cricket pitch as claimed in claim 5 in which the separate geotextile lined vertical section is filled with clay for better retention of the stumps.

7. A method of constructing a synthetic cricket pitch comprising the steps of: i. excavating an elongate trench in a soil surface; ii. laying a first geotextile layer in the bottom and sides of the excavation to isolate the structure from the surrounding soil; iii. filling the trench to a partial depth with a layer of stone; iv. compacting the stone; v. in an area of the trench where the ball is intended to bounce in front of a stump position covering the stone layer with a geotextile layer; vi. filling the trench with a further layer of hard porous material; vii. compacting the hard porous material; viii. covering the hard porous material with a synthetic turf material; and ix. securing the synthetic turf material.

8. A method as claimed in claim 7 in which the area of the trench where the ball is intended to bounce comprises a central area of the pitch between two wicket positions.

9 A method as claimed in claim 8 in which following step vii. the method further comprises i. removal at each stump position of a vertical section to form a hole; ii. lining the hole forced by the removal of the vertical section with a third geotextile to form a vertical box; iii. filling the box with a medium suitable for retention of the stumps.

10. A method as claimed in claim 8 or 9 in which the medium is clay.

11. A method as claimed in any one of claims 7 to 10 in which prior to step vii. a shock pad is placed on the hard porous material.

12. A synthetic grass cricket pitch substantially as described with reference to the accompanying drawings.

13. A method of constructing a synthetic grass cricket pitch substantially as described with reference to the accompanying drawings.