WO2002073766A1

WO2002073766A1 - Trench cover

Info

Publication number: WO2002073766A1
Application number: PCT/GB2002/001161
Authority: WO
Inventors: Simon Edward Freebairn
Original assignee: M2 PROJECT SOLUTIONS Ltd
Current assignee: M2 PROJECT SOLUTIONS Ltd
Priority date: 2001-03-14
Filing date: 2002-03-13
Publication date: 2002-09-19
Anticipated expiration: 2003-09-14
Also published as: GB0106230D0

Abstract

A trench cover (10) comprises an elongate load bearing member (12) adapted to, in use, overlie a trench (20), wherein said load bearing member (12) is manufactured from a plastics material.

Description

Trench Cover

The present invention relates to a trench cover and in particular to a trench cover for use in covering a subterranean trench adapted to house power cables.

It is common for subterranean trenches to be utilised in electricity substations for the routing of power cables. Typically the trench comprises plurality of channel members and channel cover members which are manufactured from reinforced concrete. Each cover member, in use, overlies the channel member so as to shield and protect the cables routed therein. The covers are removable so as to permit access to the cables, for example, for maintenance purposes. While most such covers are manufactured from reinforced concrete, some are manufactured from concrete which is not reinforced. These un-reinforced covers may become damaged, for example by rough handling, and can break without warning when a load is applied thereto.

The covers are typically some 900 millimetres long by 300 millimetres wide by 50 millimetres deep and weigh in the region of 40 to 90 kilograms. It will be appreciated that careful handling of a cover of this weight and size is necessary so as to reduce the possibility of injury. The reinforced concrete covers are also susceptible to damage if dropped or incorrectly stored and cannot easily be cut if a non-standard shape or length of cover is required. The covers may also deteriorate over time due to corrosion of the reinforcing rods and/or frost damage.

According to a first aspect of the present invention there is provided a trench cover comprising a plurality of spaced elongate load bearing members adapted to, in use, engage support shoulders of a trench, and a panel member spanning said elongate members, wherein said elongate members are manufactured from a plastics material.

The plastics material may be a recycled plastics material such as high density polyethylene. Other plastics materials may be utilised including a mixture of a plastics material and a filler material. Such composite material may comprise a thermoplastics material mixed with wood chippings, with the plastics material acting as a binder for the wood chippings. Alternatively the composite material may comprise a plastic and clay mixture. In one embodiment the panel member is separate from and overlies said elongate members. The panel member may be manufactured from a plastics material, and preferably a recycled plastics material. The panel member may be manufactured from low density polyethylene. As described above the panel member may alternatively be manufactured from a thermoplastic material mixed with a filler material The panel member is joined to said elongate members by any appropriate means. Such means may include pins, screws or other like fixings, or alternatively adhesive. Alternatively the panel member may be joined to the elongate members by a plastic welding operation.

In an alternative embodiment where increased load resistance is required, for example where the cover is intended to support the weight of a vehicle, the panel member may be manufactured from metal, for example steel. In such an embodiment the panel member is preferably provided with a protective coating so as to prevent rusting thereof. In a preferred embodiment the metal panel member is planar, however it will be understood that the panel member may be of different configurations, for example, concave or convex.

The elongate members may be provided with reinforcing means. Such reinforcing means may take the form of one or more reinforcing members formed integrally therewith. The or each reinforcing member may be manufactured from steel.

In an alternative embodiment the cover may be of unitary construction wherein the elongate members are formed integrally with the panel member. In such an embodiment the cover may be formed by, for example plastics moulding or extrusion.

Preferably the cover is provided with one or more slots adapted to receive a lifting key, in use. In addition, or as an alternative, to said slots, the cover may be provided with one or more finger holes. The upper surface of the cover is preferably textured so as to provide an anti-slip surface.

According to a second aspect of the present invention there is provided a trench cover comprising an elongate load bearing member adapted to, in use, engage support shoulders of a trench, and a panel member overlying said elongate member, wherein said elongate member is manufactured from a plastics material.

According to a third aspect of the present invention there is provided a trench cover comprising an elongate load bearing member adapted to, in use, engage support shoulders of a trench, wherein said elongate member is manufactured from a plastics material and the upper surface is textured so as to provide an anti-slip surface.

According to a fourth aspect of the present invention there is provided a trench cover comprising an elongate load bearing member adapted to, in use, engage support shoulders of a trench, wherein said load bearing member is manufactured from a plastics material by an extrusion process.

In such an embodiment the cover may be substantially rectangular in cross-section. The cover may be solid throughout or, alternatively, may have internal cavities or hollows.

Embodiments of the present invention will now be described with reference to the accompanying drawings in which:

Figure 1 shows a top plan view of a trench cover in accordance with an embodiment of the present invention;

Figure 2 shows an end view of the cover of figure 1 ;

Figure 3 shows a cross-sectional view of a the trench cover of figure 1 fitted to a trench;

Figure 4 shows an end view ^"of a trench cover according to a second embodiment of the present invention;

Figure 5 shows an end view of a trench cover according to a third embodiment of the present invention;

Figure 6 shows an end view of a trench cover according to a fourth embodiment of the present invention; Figures 7a to 7g show simplified underside plan views of various covers according to the present invention;

Figure 8 shows a cross-sectional side view of a trench cover according to a fifth embodiment of the present invention;

Figure 9 shows a plan view of the cover of figure 8; and Figures 10 and 1 1 show cross-sectional views of alternative cover constructions.

Referring firstly to figures 1 to 3 there is shown a trench cover generally designated 10. The cover comprises a pair of spaced elongate load bearing members 12, 14 upon which is provided a panel member 16. The panel member 16 is provided with slots 18 which enable the cover 10, in use, to be lifted with an appropriately shaped key. the cover 10 may be provided with a a single panel member 16 or, alternatively, a plurality of panel members 16. The elongate members 12, 14 have, in the embodiment shown, a uniform rectangular cross-section and are manufactured from plastics material by an extrusion process. It will be appreciated that the elongate members in an alternative embodiment may be of non-uniform cross-section. The plastics material is in a preferred embodiment a recycled plastics material, for example, high density polyethylene (HDPE) having a density in the region of 945 Kg/m³ and a tensile strength in the region of 21 N/mm². The panel member 16 is also manufactured from a plastics material. In a preferred embodiment the plastics material is a recycled plastics material such as low density polyethylene sheet having a density in the region of 65 Kg/m³ and a tensile strength in the region of 9.5 N/mm².

The elongate members 12, 14 are joined to the panel member 16 by appropriate fixing means. The fixing means may comprise a plurality of spaced pins of, for example, stainless steel. Alternatively the elongate members 12, 14 may be bonded to the panel member 16 by adhesive. In yet a further embodiment the elongate members 12, 14 may be attached to the panel member 16 by a plastics welding, plate welding or soldering operation. For example a melted plastic material may be applied to the mating faces of elongate and panel members 12,14,16 prior to assembly, the plastics material, upon solidification, serving to bond the members 12,14,16 together.

It will be understood that the elongate 12,14 and panel members 16 may be of any dimension required to suit a particular application. To fit to a standardised cable trench of the type utilised in electricity substations the elongate members 12, 14 are typically 900 mm long by 90 mm wide by 38 mm thick and the panel member 16 900 mm long by 300 mm wide by 12 mm thick.

Figure 3 shows a cover 10 fitted to a trench 20. The trench 20 is typically formed from reinforced concrete and is provided with opposed shoulders 22 on either side a channel 24 within which cables 26,28 can be routed. The elongate members 12, 14 rest on the shoulders and do not extend downwardly into the channel 24 with the result that the cover 1 spans the trench 20. The upper surface of the panel member 16 is provided flush with the ground 30.

Figures 4 and 5 show alternative embodiments of the present invention. Figure 4 shows a trench cover having an additional elongate member 32 aligned with the centreline of the panel member 16. In such an embodiment it will be understood that the slots 18 are repositioned so as to be provided on the panel member 16 between respective elongate members 12,14,32. An additional elongate member 32 may be required where the cover 10 is required to carry additional load.

Figure 5 shows a single piece cover 10 wherein the elongate members 12, 14 are formed integrally with panel member 16. The cover 10 may be formed by any appropriate means such as injection moulding or extrusion. The elongate members 12,14 include reinforcing means in the form of steel beams 34,36. Such reinforcing means may optionally be included to enhance the strength of the cover. In yet a further embodiment, not shown, the panel member may be manufactured from steel and the elongate members from plastics material. In such an embodiment the panel member is provided with a protective coating such as a galvanised coating. Alternatively the panel member may be provided with a powder coating The use of a steel panel member serves to increase the load bearing capacity of the cover and enables the cover to be used in places where vehicular access over the trench is required.

Figure 6 shows yet a further embodiment of the present invention wherein the cover, comprises a single elongate load bearing member 12 having a panel member 16 provided on an upper surface thereof. The panel member 16 may comprises a plastics material or alternatively may^"be manufactured from metal.

Figures 7a to 7g show underside plan views of trench covers 38 according the present invention. The covers 38 comprise a panel 40 and varying numbers of elongate members 42. The covers 38 are further each provided with two or more finger holes 44 which enable the covers to be lifted, in use. It will thus be appreciated that covers in accordance with the present invention may be provided in a variety of configurations so as to fit to trenches of varying shapes. The embodiments of figures 7a to 7g show covers 38 having two, three and five elongate members 42 and arrangements of two or four finger holes 44. The covers 38 are of various lengths and widths and have differing spacings between the elongate members 42.

While the embodiments of the covers 38 shown in figures 7a to 7g are substantially rectangular it will be appreciated that the covers 38 may be provided in alternative configurations. A cover may, for example, be provided in a "T" shape (not shown). Such a "T" shaped cover may be utilised at the intersection of a first trench at right angles to a second trench. It will be noted that in the embodiments hereinbefore described the elongate members are aligned substantially parallel to one another and , in use, traverse the trench in a direction substantially perpendicular to the longitudinal axis of the trench. It will further be appreciated that the elongate members may be provided with alternate orientations, for example disposed diagonally with respect to the sides of the trench. A mixture of perpendicular and diagonal elongate members may be provided so as to give a cover the required strength characteristics. In yet a further embodiment a plurality of elongate members may be provided at right angles to one another in a lattice-like formation.

Referring now to figures 8 to 11 there is shown a further embodiment of a trench cover generally designated 46. The cover 46 is of unitary construction comprising upper and lower skins 48, 50, side walls 52, 54 and internal webs 56 extending between the skins 48, 50. The webs 56, side walls 52, 54 and skins 48, 50 define a plurality of channels 60 which extend through the cover 46. Finger holes 58 are provided so as to enable the cover 46 to be lifted and positioned, in use. The cover 46 is manufactured by an extrusion process from a thermoplastics material. As described above the thermoplastics material may comprise a mixture of a thermoplastic and a filler. It will be appreciated that the use of an extrusion process necessitates that the finger holes 58 be formed in the cover 56 after extrusion thereof.

Figure 8 shows a cross-sectional view of a cover 46 wherein the channels 56 are rectangular in cross-section. It will be appreciated that the channels may be of alternative shapes, with triangular and circular forms being shown in figures 10 and 1 1.

The present invention offers significant advantages over prior art covers. The use of plastics materials significantly reduces the weight of the cover and hence renders the cover easier and safer to move and handle. Typical concrete covers exceed the legal lift weight for one person, while covers according to the present invention weigh less than said legal lift weight. The cover can be easily cut to required shapes and lengths, and requires little or no subsequent remedial treatment or protective measures. Such trimming does not require specialist safety equipment and material trimmed from the cover is non-toxic. The cover is highly resistant to chemical attack, is non absorbent and thus may be steam cleaned.

As described above the covers according to the present invention are highly resistant to damage due to such factors as, for example, mishandling, environmental attack and the like and hence are much less likely to fail in use. Covers according to the present invention can readily utilise recycled plastics materials. A further advantage of the covers of the present invention stems from their lighter weight when compared to prior art concrete covers. The lighter nature of the covers means that a greater number can be transported per lorry load with a consequent reduction in transport costs and vehicle emissions.

Claims

oClaims

1. A trench cover comprising an elongate load bearing member adapted to, in use, overlie a trench, wherein said load bearing member is manufactured from a plastics material.

2. A trench cover as claimed in claim 1 wherein said plastics material is a thermoplastic material.

3. A trench cover as claimed in claim 1 or claim 2 wherein said plastics material comprises a mixture of a plastics material and a filler material.

4. A trench cover as claimed in any preceding claim wherein said elongate load bearing member is manufactured by an extrusion process.

5. A trench cover as -claimed in claim 4, said load bearing member having opposed skins and side walls defining a cavity, said cavity being open ended.

6. A trench cover as claimed in claim 5 wherein said load bearing member includes at least one web provided between said side walls or said skins, said at least one web dividing said cavity.

7. A trench cover as claimed any preceding claim wherein said cover includes at least one lifting aperture.

8. A trench cover as claimed in any preceding claim, said elongate load bearing member being adapted to engage support shoulders of a trench, in use.

9. A trench cover as claimed in claim 1, said cover comprising an elongate load bearing member, and at least one panel member spanning said elongate member.

10. A trench cover as claimed in claim 9 wherein said cover comprises a plurality of load bearing members, and at least one panel member spanning said elongate members.

1 1. A trench cover as claimed in claim 9 or claim 10 wherein said at least one panel member is separate from and overlies the or each elongate member.

12. A trench cover as claimed in claim 11 wherein said at least one panel member is manufactured from a plastics material.

13. A trench cover as claimed in claim 11 wherein said at least one panel member is metal.

14. A trench cover as claimed in any of claims 9 to 13 wherein said at least one panel member is attached to the or each elongate member by fixing means.

15. A trench cover as claimed in any of claims 9 to 13 wherein said at least one panel member is attached to the or each elongate member by adhesive.

16. A trench cover as claimed in any of claims 9 to 13 wherein said at least one panel member is attached to the or each elongate member by one or more welds.

17. A trench cover as claimed in any of claims 9 to 15 wherein the or each elongate member includes at least one reinforcing means.

18. A trench cover as claimed in claim 17 wherein said reinforcing means comprises a reinforcing member formed integrally with the elongate member.

19. A trench cover as claimed in claim 9 or claim 10 wherein said cover is unitary construction with the or each elongate member being formed integrally with said at least one panel member.

20. A trench cover as claimed in any of claims 9 to 19 , the cover including at least one lifting aperture.

21. A trench cover as claimed in any preceding claim wherein the upper surface of the cover is textured so as to provide an anti-slip surface.