Apparatus and method for use in ground works

This invention relates, amongst other things, to an apparatus and method for use in ground works, for example an apparatus and method for providing a substantially even surface on uneven ground.

Current methods of levelling an uneven ground surface include using a theodolite or inclinometer to measure the slope of ground and then removing raised areas of ground and infilling recessed areas of ground, for example using an excavator. Such methods often require specialist training. Moreover, the logistics and cost of hiring the relevant equipment is not suited to domestic applications such as garden or driveway improvements.

It is an object of the invention, amongst other things, to provide an alternative apparatus and/or method for levelling an uneven ground surface.

According to a first aspect of the invention, there is provided an apparatus for providing a substantially even surface on uneven ground, the apparatus comprising a plurality of arms and legs, wherein the legs are of variable length and are adapted for location in a substantially upright orientation, each arm adapted for connecting two legs, so that together the arms and legs form a grid which is adapted to retain infill and to define a plane in which the uppermost parts of each arm are substantially flush to allow infill to be screeded along the arms.

An advantage of the apparatus is that it requires only basic training and minimal equipment. The apparatus is preferably modular and therefore can be used in relation to any type and size of ground area, and does not need to be pre-built to one or more specific designs. Instead, the apparatus can be assembled on-site to suit the specific site requirements. A constructor simply selects appropriate components from a bulk supply, which may be stored in a vehicle or on-site container. Straightforward use of a spirit level, for example, ensures that the constructor is able to use the apparatus to provide the required plane surface.

Typically the plane is substantially flat and more preferably the plane is substantially horizontal. Of course, the plane may be a slope or define a concave or convex curve.

The length of the legs may be varied by any suitable means. In a simple embodiment, the legs are driven into the ground by different amounts. However, in preferred embodiments the legs may be extendible or lengthened by adding one or more extensions.

The legs and extensions may each comprise a strut having a major diameter at one end and a minor diameter at the opposite end, whereby the major diameter of a leg may be connected to a minor diameter of an extension, for example. The legs and extensions may comprise tapered struts.

The legs and extensions may be connected together through a push-fit or may be. adapted to be connected together through a latch.

The legs are preferably from 50 mm to 200 mm in length, more preferably from 100 mm to 150 mm, and have a preferred diameter from 25 mm to 75 mm. Preferably the extensions are from 50 mm to 300 mm in length, for example 50 mm, 100 mm and 300 mm length sections may be provided, with a preferred diameter from 25 mm to 75 mm.

The use of one or more extensions allows for a relatively coarse adjustment of the distance between an arm and the uneven ground. In addition, one or more spacers may be provided between adjacent components to allow fine adjustments.

In a preferred embodiment, washers are provided for positioning around a pin formed at an end of a leg or extension. The washers preferably correspond in diameter to the legs or extensions and have a depth of between 3 mm and 9 mm, and most preferably a depth of 6 mm.

In an alternative apparatus, the legs may comprise two or more struts linked together in a telescopic manner or may comprise screw-threaded components.

The arms are preferably supplied as fixed lengths, for example between 600 mm and 4800 mm in length, more preferably between 900 and 1200 mm long. The arms may comprise a rectangular, circular or inverted 'T' cross-section, preferably with a depth of between 9 mm and 25 mm. With respect to inverted 'T' cross-sections, the 'depth' refers to the thickness of the horizontal stroke rather than the height of the vertical stroke.

The legs may driven into the ground or may be positioned on an existing ground surface, e.g. using a footing adapted to receive a leg or leg extension. In one embodiment, the footing

includes a cup or recess of between 50 mm and 100 mm in height into which a leg may be inserted. The leg and footing may be connected by a loose fit, a push fit or by having a latch or clip. One or more of the feet may comprise a substantially flat plate, e.g. having a depth of between 9 mm and 25 mm and having a cylindrical cup upstanding therefrom. The plate may be rectangular and have a length and width of the between 100 mm and 200 mm.

One or more legs or extensions may be adapted at the uppermost end to directly connect to an arm, for example having a protrusion for insertion into a hole or recess defined in an arm. Alternatively, the leg or extension may comprise a hole or recess for receiving a protrusion defined on an arm. The upper end of a preferred leg and extension comprises a protrusion, such as a pin, e.g. for insertion into a recess in an arm or in an intermediate joint or in a correspondingly shaped recess in the underside of a leg or extension. The pins may be from 15 mm to 30 mm long, more preferably 25 mm long. The diameter of the pin is preferably less than the diameter of the leg or extension of which it forms a part, for example from 6 mm to 37 mm.

The apparatus may comprise a joint adapted to connect one or more arms to a leg. The joint may be provided as a separate component to the arm and/or leg. The joint may be adapted in any suitable way, for example in the ways discussed above, for connecting leg or extensions to arms. Alternatively, or in addition, the legs or extensions may be adapted at the uppermost end to connect to the joint, for example in the ways discussed above.

A preferred joint comprises a substantially flat plate having channels or recesses for receiving the end of one or more arms. Preferred embodiments have joints which are configured for receiving up to four, six and/or eight arms.

Preferably, the length and width of the plate is between 75 mm and 150 mm, with a maximum depth of 32 mm. The joint may comprise a hole, recess or protrusion to receive an end of a leg or leg, preferably of sufficient size to allow the joint and to be readily located on leg or extension, wherein the interconnection permits the joint to swivel with respect to the leg or extension. This allows the opposite end of one or more arms attached to the joint to be located in another joint without straining the assembled apparatus.

The apparatus may further comprise a removable protector which can be placed over the uppermost end of the leg or extension when the leg or extension is to be driven into the ground, e.g. using a mallet. For a leg or extension having a cylindrical pin at its upper end,

the protector may be a tube, the bore of which is wide enough to allow the tube to be easily located on and removed from the pin and narrow enough to allow the tube to sit on the leg or extension.

It will be understood that the apparatus provides a modular frame, preferably in the form of a rectangular grid, that can be assembled to permit an even surface to be formed.

The apparatus is preferably suitable for receiving one or more tray or plate type bearing members, e.g. supported on the arms of the assembled grid. Fill material can then be placed into or onto the bearing member, for overlaying with one or more materials such as soil, concrete, grass or paving slabs.

According to a second aspect of the invention, there is provided a method for providing a substantially even surface on uneven ground, the method comprising the steps of defining a space in which infill can be retained and infilling that space, the space having a substantially plane upper limit, wherein the method of defining the space comprises the steps of positioning a plurality of legs in a grid arrangement, wherein each leg is positioned in a substantially upright orientation; connecting the plurality of legs to a plurality of arms; determining whether the arms define a substantially plane upper limit in which the uppermost parts of each arm are substantially flush to allow infill to be screeded along the arms; and if necessary, adjusting one or more legs to bring the arms into a position in which the arms define a substantially plane upper limit; wherein each leg is of variable length.

Advantageously, only basic training is required to carry out this method.

Preferably the plane is substantially flat, e.g. substantially horizontal or sloped (whether a flat slope or curved in a concave or convex manner).

The method may incorporate one or more features from an apparatus in accordance with the first aspect of the invention. Connection between the arms and legs maybe direct or indirect, e.g. via a joint or other connector intermediate a respective leg and arm.

The method may further comprise screeding the infill to generate a substantially level surface, and may further comprise compacting the infill. The method may also include a preparatory step of removing a volume of top-soil or other upper ground layer prior to the positioning of the legs.

Trays or load bearing plates may be supported by the grid/frame, wherein fill material can be spread or compacted over the trays/plates within the boundary defined by the frame.

The assembled grid/frame may act as a load bearing structure, for taking arid/or transferring loads from an upper layer, such as a paved surface.

There is also provided an apparatus for providing a substantially even surface on uneven ground, the apparatus comprising a plurality of legs for location in a substantially upright orientation and a plurality of arms for connection between the legs so as to form a grid which defines a plane with the uppermost parts of the arms substantially flush to allow infill to be screeded along the arms, wherein the arms may comprise inverted T-sections. The legs may be extendible and/or may be driven into the ground by different amounts.

There is further provided a method of providing a substantially even surface on uneven ground, the method comprising the steps of positioning a plurality of legs in a grid array with each leg in a substantially upright orientation, and arranging arms, preferably of inverted T- section, between the legs so as to form a grid which defines a plane wherein the uppermost parts of the arms are substantially flush to allow infill to be screeded along the arms. The legs are preferably of variable length, for example the legs may be extendible and/or may be driven into the ground by different amounts.

According to yet a further aspect of the invention, there is provided an apparatus for creating a level surface on uneven ground, the apparatus including a modular frame having interconnecting arms and legs for defining a grid in plan view, wherein the arms are used to define a plane surface, the apparatus further including a plurality of trays supported in apertures defined by said grid.

The trays may be planar or have a peripheral upstand so as to define a recess or chamber for receiving fill material. The frame may include arms, legs and joints corresponding to those in accordance with the first aspect of the invention.

According to another aspect of the invention, there is provided an apparatus for use in ground works, the apparatus including a plurality of elongate strips, each strip defining a retaining surface and a bearing surface perpendicular to said retaining surface, pairs of strips being intended to be laid in parallel, with the retaining surfaces aligned for retaining a fill material therebetween, the apparatus further including a cover member intended to be positioned over

the bearing surface of at least one of said strips in use, for supporting one or more ground work layers above the fill material.

According to a further aspect of the invention, there is provided a method of preparing a base layer for supporting a paving or like upper layer, using elongate strips which each define a retaining surface and a bearing surface perpendicular to said retaining surface, the method comprising the steps of providing an array of said strips in a ground surface, wherein pairs of said strips are arranged with their retaining surfaces generally parallel to one another, fill material being thereby retained between opposing retaining surfaces, and providing one or more cover members over said strips for supporting an upper layer over said fill material.

This apparatus and method is of particular advantage in the construction of paved driveways. In particular, the retaining surfaces provide lateral reinforcement to the fill area between the strips. The reinforcement provided by the strips can reduce the depth of fill that would otherwise be necessary to support the upper layer. Not only does this reduce the required fill volume, it can also significantly reduce the level of excavation required for a given site, thereby reducing labour and landfill costs.

Furthermore, compressive loads from the intended upper layer can be dissipated across the fill area by the cover member and transmitted to a ground layer below the fill area, via the strips, thereby reducing the load on the fill area. This can reduce the effects of rutting that might otherwise occur if voids were to form in the fill material beneath the upper layer.

The apparatus and method is relatively simple and efficient to implement, in terms of both labour and fill material. Of course, the apparatus and method can also be used to similar advantage in the construction of other pavement or road type structures, such as car parks, roads and pedestrian areas. Alternatively, the upper layer can be formed from turf or hardcore, for the creation of tennis courts or other such enclosed sports areas.

The strips are preferably T-shaped in cross-section, whereby the stroke of the T is intended to be driven or positioned in the ground or like surface and defines a pair of elongate retaining surfaces, one on either side of the stroke, the cross-member of the T defining an elongate bearing surface. The strips are preferably of plastics material.

The cover member may be in the form of at least one section of plastic sheet which can be used to span between pairs of said strips, so as to support an upper layer such as a turf or

block paving layer (preferably with an intermediate layer of sand beneath the upper layer). In such applications, it is preferred if the sheet is secured to adjacent pairs of strips, so that the sheet is fixedly suspended between adjacent strips.

In a preferred embodiment, the cover member is in the form of rigid tray or plate, preferably of plastics material, wherein a plurality of said trays/plates can be supported over the fill area between adjacent strips, supported by the retaining surfaces of the strips. The trays/plates may be configured for tessellation and/or configured to be laid in rows, preferably staggered, to create an interleaved impression in plan view.

An upper layer can then be supported by the plates/trays, the load being spread by the plates/trays and passed down through the strips, via the bearing surfaces.

Adjacent plates/trays may be interconnected with one another and/or connected to respective strips. The plates/trays are preferably configured to span at least one or pair of opposing strips. Typically, the strips will be laid at 1 metre centres for example.

The frames and strips referred to above can be used to replace hardcore and other such fill materials in certain applications, in particular shallow paving applications, such as domestic patios and the like. The strips are ideally suited for domestic applications, such as patios and drive ways.

The frames, in particular, can be used above ground level, supported directly on an existing ground surface. As mentioned above, the frames are readily suited for use in a recessed area, either wholly or partially located below ground level, for providing a level surface substantially at the adjacent ground level or protruding above the adjacent ground level.

The frames are ideally suited for use in setting up a floor screed and are advantageous in that they provide integral reinforcement for the screed.

The frames can be used well below ground as part of, or as a support for, a soakaway, for example, but can also be used above ground to provide an elevated support for water tanks or other upper structure.

Other aspects and features of the invention will be readily apparent from the dependent claims and the following description of several preferred embodiments, made by way of example only, with reference to the following drawings, in which:

Figure 1 is an exploded schematic view of components of a system for levelling an uneven surface;

Figure 2 is a schematic top-view of a frame constructed using the system for levelling an uneven surface;

Figure 3 is a schematic side view of section A-A of Figure 2;

Figure 4 is a schematic side view of section B-B of Figure 2;

Figure 5 is a schematic cross section through another apparatus for providing a plane base for an upper layer of paving of the like; and

Figure 6 is a schematic plan view of a domestic driveway being re-surfaced using the apparatus of Figure 5.

Referring firstly to Figures 1 to 4, there is shown aspects of apparatus for use in setting out an even ground surface over an uneven ground surface. In general terms, the apparatus includes a framework which is supported above an existing ground level on an array of legs, wherein the framework is used to define a level plane above the existing ground level. The height of the framework relative to the surface over which it is intended to be supported can be varied by varying the length of the one or more of the legs, e.g. by driving the legs into the ground by different amounts or by using one or more extensions to increase the length of the legs.

An example of a leg for use with the apparatus is indicated generally at 10 in Figure 1, which consists of first and second strut type members 12, 18, each having a pin 14, 20 projecting from its upper end and recess 16, 22 formed in its lower end, whereby two or more members 12, 18 can be interconnected in a stack so as to increase the length of the leg 10. It may be preferred to consider the lower member 12 in Figure 1 as a leg section and the upper member 18 as a leg extension.

A C-shaped washer 24 is configured to fit around either of pins 14, 20 for providing a small increase in the effective length of the leg 10.

In non-illustrated embodiments, the lower end of at least one of the leg sections 12 or leg extensions 18 is tapered or otherwise pointed, so as to be suitable for being driven into the ground. A tubular protector 26 having a bore 28 can be positioned over the pins 14, 20 when

driving the leg 16 into the ground, so as to protect the upper end of the leg 10 from applied force.

In the illustrated embodiment, the lower end of the leg section 12 is intended to be received in a cylindrical cup type recess 32 on the upper side of plate type footing 30, by means of which the leg can be located on a ground surface.

In one method, plate 30 is positioned on a ground surface and anchored using pegs (not shown) located through apertures 34 in the plate 30. The lower end of the leg section 12 is then fπctionally fitted into the recess 32, e.g. by tapping its upper end with a mallet so as to drive the lower end of the leg 10 into the recess 32. It may be preferred to use the protector 26 during this operation. A projection (not shown) may be provided in the recess 32 for frictional engagement in the recess 16 in the lower end of the leg section 12. The height of the leg can then be increased, as appropriate, using one or more leg sections 12, leg extensions 18 or washers 24.

As mentioned above, an array of legs is used to support a framework. An example is shown in Figure 2, wherein the framework (indicated generally at 36) consists of grid like array of arm sections 38, each arm 38 being connected between a respective pair of legs 10. The arms 38 are elongate and of fixed length, for example 1000 mm. Diagonally arranged arms (not shown) may also be included in the array, if desired.

In certain embodiments, the arms 38 can be connected directly to the legs 10 in the array. However, it is preferred if intermediate joints are used, hi Figure 1, the joint is in the form of a nodal connector 40 which is intended to be fitted onto the upper end of a leg 12 or extension 18 (although it may be supplied integral with a leg or extension, if desired). In this embodiment, the connector 40 defines four channels 42, each channel intended to receive one end of a respective arm 38. Of course, the connector may be configured for receiving up to eight arms, e.g. if one or more diagonal arms are to be included in the framework 36.

In Figure 1, only the ends of one example of an arm 38 for use with the apparatus have been illustrated, these being complimentary in shape to the channels 42 formed on the connector 40. Of course, other complimentary shapes may be sued, such as circular or rectangular sections/recesses.

The framework 36 is preferably constructed piece by piece starting from a first leg 10 positioned at a desired location in or on the ground, whereby one end of a first arm 38 is connected to said first leg 10, e.g. via a first connector 40, and the opposite end of the first arm 38 is then used as a guide for correctly positioning a second leg 10, and so on until a grid of the required size and shape is defined by the arms.

When two or more legs 10 are in position, the level of the supported arms 38 can be assessed, e.g. using a spirit level, whereupon it may be necessary to lower or raise the level of one or more arms, e.g. by inserting one or more washers 24, leg sections 12 or leg extensions 18, one or more ends of the arm 38, until the arm 38 is arranged at the desired level. This is continued until the framework 36 defines a level plane, preferably with the tops of adjacent arms 38 being flush with one another.

Once assembled, the arms 38, legs 10 and ground define a cage for receiving infill material 50 (see Figures 3 and 4). m one method of use, the cage is infilled to, or slightly above, the level of the arms. The surface of the infill is then screeded using the upper surface of the arms as a screeding guide. The infill may then be compacted and the process repeated until the infill is sufficiently compact and level, relative to the framework. Subsequently, the infill or framework may be overlaid with a material such as paving blocks or grass or a continuous bituminous surface.

In the embodiment of Figures 3 and 4, the arms 38 are of inverted T-section, wherein the distal end 46 of the down stroke of the T acts as the screeding surface and the cross stroke 48 of the T is used as a planar base to be received on the nodal connectors 40, for example. The two ends of the each arm may be profiled for complimentary engagement with recesses or channels on the nodal connectors 40 or the legs 10, as required, e.g. in the manner shown in Figure 1.

To create a soak-away, a coarse infill material maybe used so that even when it is compacted there, are voids within the cage defined between the infill particles, to accommodate rainfall for example. The course layer can then be used as a drain to channel a flow of rain water or the like.

When levelling an uneven soft surface, it may be preferred to drive the legs into the ground, thus avoiding the need for footings 30. Prior to constructing the grid, it may be preferable to remove the top-soil, whether or not it is intended to use the feet 30.

The cage may be used to support a series of trays, wherein at least a portion each tray is configured to fit between one of the grid-type openings as defined by the framework in plan view. Typically, the trays will include a flange or step which is intended to be supported on the arms of the framework. The trays preferably define a chamber above and/or below the plane surface defined by the upper flush surface of the framework, for receiving an infill material, as required. Alternatively, the trays may be pre-filled, for example.

Referring now to Figure 5, another apparatus for use in ground works is indicated generally at 100. The apparatus includes a plurality of elongate strips 102 of T-shaped cross-section, whereby the stroke of the T is intended to be driven or positioned in the ground or like surface and defines a pair of elongate retaining surfaces 104, one on either side of the stroke, the cross-member of the T defining an elongate bearing surface 106.

The strips 102 are intended to be laid in parallel, so as to define pairs of opposing retaining walls for supporting a fill material 120 therebetween. The position of the flat bearing surfaces 106 relative to one another can then be compared, for the purpose of defining a substantially plane surface across the array of strips 102, for example using a plumb line. The height of each strip above a base ground level 122 can be changed, for example by driving a strip further into the ground, until a plane surface between adjacent strips 102 has been suitably defined.

Prior to or during the setting of the strips 102 in the ground at a plane surface defining level, fill material can be provided between the retaining walls and screeded to an approximate plane level, for example using the upper surface of the strips 102 as a guide.

When the strips 102 have been correctly positioned, the fill material is finally screeded to said plane level, ready for the laying of an upper surface, for example of block paving, over said strips 102 and fill material, hi a preferred embodiment, one or more load bearing elements are rested on the bearing surfaces 106 of the strips 102, preferably spanning across adjacent pairs of strips 102, for supporting the intended upper layer.

hi the preferred embodiment, a plurality of rigid plastic plates or trays 108 are supported over the fill area between adjacent strips 102. The plates 108 are preferably arranged in staggered rows so as to create an interleaved impression in plan view. An upper layer of block paving 110 can then be laid over the fill material, supported by the plates/trays on the bearing surfaces 106 of the strips 102.

In another embodiment, the cover is a continuous plastic sheet (or a section thereof) which is secured to adjacent pairs of strips 102, so that the upper layer can be effectively suspended between adjacent strips 102.

The strips 102 will typically be formed of plastics material which can be cut to length or supplied in pre-cut lengths. The strips 102 will typically be laid at ¹ A metre, 1 metre or 1 1/2 metre centres, although lesser and greater distances may be appropriate for different applications.

Of course, it may be preferred to interconnect the strips using ties of struts, prior to providing the upper layer or cover, so as to define a working grid.

In the apparatus of Figure 5, the T-sections preferably have a depth of between 100 mm to 250 mm and a similar width. The strips can be secured in the ground using spaced pins, for example.

Figure 6 shows the apparatus 100 of Figure 5 being used to re-pave the driveway 200 of a domestic building 210. The driveway 200 extends from the pavement 240 in front of the building 210 to a garage 220 and spans between the building 210 and a flower bed 230.

Firstly, the existing driveway surface is removed and disposed of, so that an array of parallel strips 102 can be positioned along the recessed area. The strips 102 can be cut or ordered to size, so as to fit neatly in the recessed area between the adjacent structures. Fill material can then be used to bring the level of the ground in the recessed area to a predetermined subsurface level, and compacted where necessary. The position of the strips 102 can then be assessed and modified, where necessary, to define a substantially plane surface onto which an upper paved surface can be laid.

In this embodiment, tray or plate type bearing members 108 are laid on the correctly positioned strips 102 in a staggered array, as viewed in plan, and are secured to the bearing surfaces of the strips using pins (not shown). It is preferred if each, or substantially all of the bearing members span the space between at least one pair of opposing strips 102. In this embodiment, the array of strips 102 is such that the majority of the plates span three or four of the parallel strips 102.

Once the bearing members 108 are in place, an upper layer of paving can be applied in conventional manner.

The strips 102 provide lateral restraint and act to transfer load from the upper paved surface to the subsurface material into which the strips have been positioned. The strips 102 can be supported on peg or pin type piles provided at either end and/or spaced along the length of the strips, to further assist in load transfer to the subsurface material. Load from the upper paved surface is spread across adjacent pairs of the strips 102 by the intermediate bearing members 108, which act as a bridge across the infill material, thereby reducing the effects of rutting in the upper surface that might otherwise occur without similar reinforcement. The system can significantly reduce the volume of material that is required to be excavated for any given project, and can reduce or eliminate the need for hardcore fill material. A plane surface level can be achieved without specialist training or equipment, and the whole system can be installed with relative ease.