AU2014100417A4 - Improved support structure for an area - Google Patents

Abstract

A surface support structure (1) for reducing the impact of a fall onto a surface, said structure including a first layer of particulate material (32) placed on or in the ground at an impact zone; a resilient mat (15) having apertures (20, 25) that are adapted to be filled by particulate material 5 and to enable fluid to pass therethrough, said resilient mat (15) located over the first layer (32); a second layer of particulate material (33) having a thickness less than the first layer (32) and being placed on the resilient mat (15); wherein the support structure (1) substantially prevents displacement of the particulate material away from the impact zone. a 25 F) G.4 -35 -32 -3 -- 31- c -3)-

Description

IMPROVED SUPPORT STRUCTURE FOR AN AREA Field of the Invention This invention relates to a support structure for an area, such as a play area or an area 5 subjected to excessive foot traffic, and to a method of installing the support structure in the area. Background of the Invention Various areas within a playground, or heavy traffic area, become very worn in a short period of time. This is particularly important in playground areas under equipment or around 10 equipment where there is potential for a child to fall from a height that can cause injury or worse, death. Such areas are for example underneath swings, monkey bars and slides, particularly at the base of the slide. Over time, childrens' feet over these heavy traffic areas displace or kick out particulate material, such as loose fill fibre material which is originally set in place to provide additional protection for the child. Rubber mats have also been used on their own that degrade 15 over time and are generally quite expensive to fit out within a playground area. The loose fill material, such as wood chips, are required to meet certain standards or specifications in order to provide a safe environment for children. Therefore the material has to be at a particular depth and maintained at that depth for a given critical height that a child may accidently fall from. The problem with many playground floor structures is that the loose fill material does 20 become displaced over time and is costly in terms of finance and time in order to maintain and replace the loose fill material. The present invention seeks to overcome one or more of the above disadvantages by providing a support structure for an area subjected to heavy use that keep maintenance and costs to a minimum while retaining loose fill material in place and therefore providing a safe 25 environment for people to use that area. Summary of the Invention According to a first aspect of the invention, there is provided a surface support structure for reducing the impact of a fall onto a surface, said structure including: 30 a first layer of particulate material placed on or in the ground at an impact zone; a resilient mat having apertures that are adapted to be filled by particulate material and to enable fluid to pass therethrough, said resilient mat located over the first layer; a second layer of particulate material having a thickness less than the first layer and being placed on the resilient mat; 2 wherein the support structure substantially prevents displacement of the particulate material away from the impact zone. Preferably the mat includes a grid pattern whereby the apertures includes a first set of apertures located adjacent the first layer of particulate material and a second set of apertures that 5 form cavities through the mat, the cavities having a diameter smaller than the apertures in the first set of apertures. The structure may further include a set of rods, wherein each rod is secured at a first end to a portion of the mat and a second end is secured in the ground. Each rod may have a hook at the first end and is positioned below the mat within the first layer of particulate material. The 10 length of each rod positioned in the ground below the first layer is preferably at least 200mm. The thickness of the first layer of particulate material may be between 100mm and 200mm. The thickness of the mat can be between 20mm and 30mm. The thickness of the second layer of particulate material is preferably at least 40mm. According to a second aspect of the invention, there is provided a method of forming a [S surface support structure for reducing the impact of a fall onto a surface, said method including the steps of: forming a first layer of particulate material on or in the ground at an impact zone; placing and securing a resilient mat over the first layer, said mat having apertures that are adapted to be filled by particulate material and to enable fluid to pass therethrough; !0 forming a second layer of particulate material over said mat, the second layer having a thickness less than the first layer; wherein the formation of said support structure substantially prevents displacement of the particulate material away from the impact zone. 25 Brief Description of the Drawings A preferred embodiment of the invention will hereinafter be described, by way of example only, with reference to the drawings in which: Figure 1 is a perspective view of an area, such as a playground, having a support surface positioned in areas of greater wear around the playground equipment; 30 Figure 2 is a plan view of a mat which is used as part of the support structure; Figure 3 is a perspective view of a portion of the mat shown in Figure 2; Figure 4 is a side view showing the components of the support structure as assembled in and on the ground; and Figure 5 is a plan view of two mats shown connected to each other. 3 Detailed Description of the Preferred Embodiment Referring to Figure 1, there is shown a perspective view of a playground 10 which has ground surface 11 substantially made of particulate material which can be any one of mulch, 5 washed sand or gravel. The mulch is regarded as loose fill material which can be material from pine chips, pine bark or rubber mulch. There is also shown playground equipment such as a swing set 12, climbing frame 13 (monkey bars) and slide 14. Areas of heavy wear, such that the particulate material is kicked out and dispersed, includes those directly underneath the swing seats (when they are in a stationary unused position), underneath the climbing frame 13 and 10 underneath the slide 15 particularly at the ladder end and at the bottom of the slide. In such places where the particulate material is kicked out, this increases the danger that a serious injury can occur to a child who falls from a given height onto the surface 11. The particulate material is designed to cushion any impact of a fall from a child. Where this has been reduced in thickness, the abovementioned areas increases the risk of injury. 15 Referring to Figures 2 and 3, the mat 15, which is made from moulded rubber, has a series of first apertures 20 having a diameter of around 20mm located at a bottom surface of the mat 15 and a series of smaller second apertures 25 located at the opposite top surface of the mat 15. The second apertures 25 have a diameter of about 15 millimetres at the top surface are linked through a substantially cylindrical opening 27 to a series of smaller 10 millimetre !0 apertures at the bottom surface of the mat 15. The smaller apertures 25 at the bottom of mat 15 are surrounded by a seat 26. The first set of apertures 20 also have a seat 21 bounded by a circular wall 22. A hollow space or cavity 28 is formed by the wall 22. Each of the hollow spaces or openings 27 are joined by respective walls 23 in a grid like pattern and have ridges 24 at the top of the wall 23 with each of the ridges 24 having a small recess 29 along its length 25 between adjoining apertures 25. The sides of walls 23 also have one or more ridges. The openings 27 and cavities 28 are designed to house some of the particulate material from the surface of the playground and prevent or substantially reduce the movement of the particulate material when it has heavy use around playground equipment. Each of the apertures 20 essentially define a grid of square cells which have in each coiner the smaller apertures 25 30 which are all linked to each other through ribbed walls. The particulate material, in this instance, pine chip particles ranges in size from approximately Imm 3 to larger sizes of 45mm x 20mm x 9mm with an average size approximately between 25mm x 20mm 7mm and 15mm x 15mm x 3mm. 4 Referring to Figure 4 there is shown a side view of the support structure 1 as it would be mounted in the ground in a playground area or any other area in which there is potential for a person to fall from a height onto the ground. A series of metal rods or poles 34 are hooked onto a respective cable tie 35 through a hook 36 at a corner of the mat 15. Each of the rods 34 are 5 made of steel and are about 400mm in length, but can be any suitable length. A layer of particulate material or mulch 32 is placed in a trench or cavity 37 that is dug out underneath the play equipment at an impact zone to a depth of between 100mm and 200mm, preferably between 150mm and 200mm (shown as thickness B in Figure 4) and this forms a first (lower) layer of particulate material (alternatively a trench is not dug out and instead a layer of particulate to material is formed of indefinite dimensions). The infill mulch layer 32 is then placed in the trench 37 and resilient mat 15 is laid over the top of the layer 32 of mulch with each of the rods 34 driven into the ground 31. About 250mm of each pole exists in the ground 31 (shown as depth C in Figure 4) and about 150mm to 200mm is located above the ground surface 30 (slightly less than B), adjusted to the actual thickness of B. The ends of the rods 34 at which the L5 hook 36 is located remains in a location underneath the bottom surface of the mat 15 for safety purposes, whereby a child would not inadvertently be able to touch or be injured by the hook 36 or rod 34. Each of the cable ties 35 are loosely connected to a nearest aperture 20 or 25 to each corner of the mat 15. The rods 34 therefore keep the mat 15 in its original position despite the movement and pressure applied by high usage areas in the vicinity of the playground equipment. ?0 Once the mat 15 is positioned in place, a further second (upper) layer 33 of mulch or particulate material of at least 40mm thickness, preferably about 50mm (or thicker up to 100mm as required) is placed over the top of the mat 15 (shown as thickness A in Figure 4). The particulate material knits in to the openings 27 and cavities 28 created by the apertures 25 and 20 and this binds the whole particulate material together and makes it difficult 25 to move or displace the material over time amid high usage. In use, a user initially digs out a small pit 37, as mentioned previously to a depth of 100mm to 200mm, preferably between 150mm to 200mm in the desired impact zone around the playground equipment. The rods 34 are then secured at each corner of the mat 15 to the cable ties 35 and a layer of mulch 32 is added into the trench 37. The mat 15 is then placed over the 30 layer 32 and the rods 34 are driven into the ground to the depths previously mentioned. The next layer of mulch 33 is then placed over the top of the mat 15. The mat 15 can be made from rubber that is flexible or any other geotextile or geosynthetic material. The examples used in this embodiment have a thickness of about 25mm (ideally any thickness between 20mm and 30mm) and are roughly 2 metres long by 1.5 metres wide and weighing between 25 to 30 kilos. 5 Figure 5 shows two mats 15 that can be joined together by intervening cable ties 35, along adjacent sides, through convenient apertures 20 or 25 on adjoining mats 15. Multiple mats 15 may be required to be tied together in situations, for example, underneath the climbing frame 13 shown in Figure 1 or underneath swings 12. As many cable ties 35 as are needed can be used 5 to joint two or more mats 15 together. Typically two to three cable ties are used along the sides of adjoining mats 15. The support structure meets the requirements of Australian Standard AS/NZS 4422:1996 "Playground Surfacing - Specifications, Requirements and Test Method". It has been tested that for a test depth of 200mm, with a lower layer of 150mm of loose fill pine chip material, a rubber [0 mat (softfall retention mat) and an upper layer of 50mm of loose fill pine chip material, the critical fall height (for example from on top of monkey bars or a climbing frame) was 3.1m. The same critical fall height was achieved without the use of a mat, that is, just with a 200mm layer of loose fill pine chip material. This shows that the softfall properties of the particulate material are maintained with the presence of the mat, however using the mat retains the particulate !5 material in place such that it is lessens the effect of dispersement of the material (particularly in the bottom layer 32) away from heavy foot traffic areas, and allows recovery of some surface material displacement caused by various impacts due to the elastic recovery response of the mat 15. If for some reason the upper layer 33 is moved over time, the mat 15 retains the lower layer 32 of particulate material in place to meet the softfall and surfacing requirements of the above 0 Standard. It is also found that the recommended installation depth for the loose fill material, according to the abovementioned Standard, is reduced with the addition of the retention mat 15. It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the present invention without departing from the scope or spirit of the invention. In view of the foregoing, it is intended that the present invention cover modifications 25 and variations of this invention provided they fall within the scope of the following claims. 30 KASPECIS\1875100AUdocx 35 6

Claims (9)

1. A surface support structure for reducing the impact of a fall onto a surface, said structure including: a first layer of particulate material placed on or in the ground at an impact zone; 5 a resilient mat having apertures that are adapted to be filled by particulate material and to enable fluid to pass therethrough, said resilient mat located over the first layer; a second layer of particulate material having a thickness less than the first layer and being placed on the resilient mat; wherein the support structure substantially prevents displacement of the particulate material iO away from the impact zone.

2. A surface support structure according to claim 1 wherein the mat includes a grid pattern whereby the apertures includes a first set of apertures located adjacent the first layer of particulate material and a second set of apertures that form cavities through the mat, the cavities tS having a diameter smaller than the apertures in the first set of apertures.

3. A surface support structure according to claim 1 or claim 2 further including a set of rods, wherein each rod is secured at a first end to a portion of the mat and a second end is secured in the ground. 20

4. A surface support structure according to claim 4 wherein each rod has a hook at the first end and is positioned below the mat within the first layer of particulate material.

5. A surface support structure according to claim 3 or claim 4 wherein the length of each 25 rod positioned in the ground below the first layer is at least 200mm. 8

6. A surface support structure according to any one of the previous claims wherein the thickness of the first layer of particulate material is between 100mm and 200mm.

7. A surface support structure according to any one of the previous claims wherein the 5 thickness of the mat is between 20mm and 30mm.

8. A surface support structure according to any one of the previous claims wherein the thickness of the second layer of particulate material is at least 40mm. [0

9. A method of forming a surface support structure for reducing the impact of a fall onto a surface, said method including the steps of: forming a first layer of particulate material on or in the ground at an impact zone; placing and securing a resilient mat over the first layer, said mat having apertures that are adapted to be filled by particulate material and to enable fluid to pass therethrough; .5 forming a second layer of particulate material over said mat, the second layer having a thickness less than the first layer; wherein the formation of said support structure substantially prevents displacement of the particulate material away from the impact zone. 20 9