GB2347707A

GB2347707A - Drainage system

Info

Publication number: GB2347707A
Application number: GB0014755A
Authority: GB
Inventors: David William Monks
Original assignee: Hodkin & Jones
Current assignee: Hodkin & Jones
Priority date: 1996-06-05
Filing date: 1996-10-09
Publication date: 2000-09-13
Anticipated expiration: 2016-10-09
Also published as: GB2347706A; GB2347706B; GB2347708A; GB0014756D0; GB2347708B; GB2347707B; GB0014755D0; GB0014754D0

Abstract

A drainage system comprises a trench extending into the ground from ground level with a plurality of channel members laid in end-to-end abutting relationship along the trench and a plurality of lid members laid in end-to-end abutting relationship over the channel members to close the channel members, each lid having a cover portion below ground level and at least one projection extending from the lid to ground level, the or each projection including a drainage hole at ground level for the passage of fluid through the lid, and the at least one projection of one lid being spaced from the at least one projection of the next adjacent lid, concrete covering the lids and surrounding the projections to ground level leaving the drainage holes exposed. The channel members are suitably those described and claimed in our U.K. patent no. 2316428.

Description

2347707 DRAINAGE ASSEMBLIES The invention relates to drainage assemblies.

A known drainage assembly comprises a generally V-shaped channel which is placed in series with similar channels in a trench. The channels are surrounded by cement and a concrete lid is then placed on the channel. The lid is provided with drainage holes that extend through the lid to allow ground water to pass through the lid into the channel.

The lid is generally made of concrete and has to be of a sufficient thickness that it can bear the loads imposed in use, which may include the weight of heavily laden lorries.

This weight and the general conditions in which such lids are placed on the channels can often lead to the lids being incorrectly located with respect to the channels. This can cause the lids to crack under load. According to a first aspect of the invention, there is provided a drainage system 20 comprising a trench extending into the ground from ground level with a plurality of channel members laid in end-to-end abutting relationship along the trench and a plurality of lid members laid in end-to-end abutting relationship over the channel 2 members to close the channel members, each lid having a cover portion below ground level and at least one projection extending from the lid to ground level, the or each projection including a drainage hole at ground level for the passage of fluid through the lid, and the at least one projection of one lid being spaced from the at least one projection of the next adjacent lid, concrete covering the lids and surrounding the projections to ground level leaving the drainage holes exposed.

According to a second aspect of the invention, there is provided a method of forming a drainage channel using a plurality of channel members and a plurality of lid members, each lid having a cover portion and at least one projection extending from the lid, the or each projection including a drainage hole for the passage of fluid therethrough, the method comprising preparing a trench, laying the plurality of channel members in end-to-end abutting relationship along the trench, the channel members being closed by the plurality of lid members, the cover portions of the lids being below ground level and the drainage holes being at ground level with the at least one projection of one lid being spaced from the at least one projection of the next adjacent lid, and then pouring concrete to cover the lids and surround the projections to ground level leaving the drainage holes exposed.

The following is a more detailed description of an embodiment of the invention, by way of example, reference being made to the accompanying drawings in which:- 3 Figure I is a perspective view of a drainage assembly including a channel and a lid with the lid shown separate from the channel for clarity, and Figure 2 is a cross-section of a part of the drainage assembly of Figure I set in concrete.

Refer-ring first to Figure 1, the drainage assembly comprises a channel 10 and a lid 11. The channel 10 is formed of glass fibre reinforced concrete.

The channel 10 is of generally V-shaped cross-section with a flat base 13 from which extends diverging lower side walls 14. Parallel upper side walls 15 extend from the lower side walls 14. An outwardly extending flange 16 projects from each of the upper ends of the upper side walls 15. The flanges 16 have flat upper surfaces 17.

An exterior surface 18 of the channel 10 is provided with three U-shaped ribs 19.

Each rib 19 lies in a plane normal to the length of the channel 10 and extends from one flange 16 to one side of the channel round the outer surface of the channel 10 to the other flange 19 on the other side of the channel 10. There is a rib 19 at each end of the channel 10 and a rib 19 at a position inter-mediate the ends of the channel 10. Of course, there may be only two ribs 19 or there may be four or more ribs 19. 20 Each rib 19 is provided with three holes 20 arranged along each portion of each rib that overlies the side walls 14,15. Thus, each rib 19 has a total of six holes 20. The 4 holes of one rib 19 are in register with the holes in the other ribs 19 in a direction parallel to the length of the channel 10.

A reinforcing bar 12 extends through each line of three registering holes 20 so that six reinforcing bars 12 are carried by the ribs 19, three along one side of the channel 10 and three along the other side of the channel 10, with the reinforcing bars 12 extending in a direction generally parallel to the length of the channel 10. The reinforcing bars 12 may be of 6mm steel rod.

ft will be appreciated that the channel 10 may carry more or less reinforcing bars 12 and that the bars may be configured otherwise than as shown in the drawings.

The lid I I is also formed from glass fibre reinforced concrete. The lid 11 is of generally rectangular shape with a length equal to the length of the channel and a width equal to the width of the channel 10 across the flanges 16.

The upper surface of the lid 11 is provided with a plurality of side-byside upwardly projecting drainage slots 2 1. Each slot 21 has rectangular front and rear walls 22 lying in respective parallel planes normal to the plane of the lid and interconnected by side walls 23 lying in respective planes parallel to the length of the channel 10. The front and rear walls 22 extend across the majority of the width of the lid I I so that the shape of each slot 21 is a narrow rectangle which is elongate in a direction transverse to the length of the channel 10.

An upstanding rib 24 extends from each side wall 23 to the adjacent side edge 25 of the lid 11.

One end of the lid I I is formed with an upwardly displaced portion defining a downwardly facing rebate 26 for receiving the opposite end of a next succeeding lid I I in a manner to be described below.

The lid I I carries a welded mesh of reinforcing bars formed by transverse bars 27 and longitudinal bars 28. These may be, for example, of 10 mm high tensile steel.

Each transverse bar 27 has a central straight portion and upturned ends 30 extending normal to the straight portion 29. The transverse bars 27 are arranged so that there is a transverse bar 27 between each pair of drainage slots 21 as well as a transverse bar 27 before each of the end drainage slots 2 1.

There are four longitudinal bars 28. One longitudinal bar extends along the comer at the upturned ends 30 of the transverse bars 27 to one side of the channel and a second longitudinal bar 28 extends along the corresponding comer to the other side of the channel 10. A third longitudinal bar 28 contacts the transverse bars 27 between the 6 ends 30 to one side of the channel 10 and the adjacent side walls 23 and the fourth longitudinal bar 28 contacts the transverse bars 27 at a corresponding position on the other side of the channel 10.

The transverse bars 27 and the longitudinal bars 28 are welded together to form an integral mesh. The upper end of each drainage slot 21 is closed by a cap 31 which may be formed from a plastics material. Each cap 31 fits tightly within the associated drainage slot 10 21 but is readily removed from the associated drainage slot 2 1. Although in Figure I the lid I I is shown separate from the channel 10, in use, the lid I I may be fixed firmly to the channel 10. An epoxy resin bond is provided between the upper surfaces 17 of the flanges 16 and the under surface of the lid 11, although 15 other forms of fixing may be used. The channel 10 and the lid I I are thus supplied as an integral unit carrying the reinforcing bars 12 and the transverse and longitudinal bars 27,28 with the caps 31 on the drainage slots 21. Since the channel 10 and the lid I I are made from glass fibre reinforced plastics material, they are light and can be readily handled. 20 In use, a trench is excavated where a channel is required. A plurality of drainage assemblies, each formed by a channel 10 and a lid I I as described above, are laid end 7 to end in the trench. For aiding alignment, the channel sections may be provided with interlocking or interconnecting parts at their ends (not shown). The depth of the trench is arranged so that the level of the surrounding ground 32 is the same as the level of the upper ends of the drainage slots 2 1. This is seen in Figure 2.

When the drainage channels have been arranged in the trench as required, concrete 33 is poured into the trench to the depth of the upper ends of the drainage slots 2 1. This flows round the exterior of both the channel 10 and the lid I I and, in particular, flows round the reinforcing bars 12 and the transverse and longitudinal bars 27, 28. As the concrete sets, these bars 12, 27,28 interlock the channel 10 and the lid I I with the concrete. This ensures that the channel 10 and the lid I I are rigidly anchored and prevents movement and cracking of the lid I I and channel 10 under loads encountered in use. This also fixes the lid relative to the channel 10 where these parts are not connected prior to concreting.

After the channel 10 and the lid I I have been set in the concrete 33, the caps 31 are removed. This opens up the drainage slots 21 which can thus receive ground water and pass it into the interior of the channel 10 for drainage.

The lid I I can bear the weights encountered in use, such as the weight of lorries passing over the lid 11. To this end, the distance between the lower surface of the lid 8 11 and the tops of the drainage slots 21 is selected to provide a depth of concrete 33 sufficient to bear such loads.

Since the upper end of each channel is closed by the associated lid 11 and the caps 2 1, there is no possibility of unwanted material such as stones entering the interior of the channels 10 once they are laid in the trench. This means that blockage of the channels as a result of such matter is avoided.

In addition, each lid I I is always correctly located in relation to its associated channel 10 (either by pre-connection or by concreting). This avoids circumstances where lids I I that are otherwise perfectly manufactured, crack in use because they are incorrectly fitted in the trench to the associated channel 10.

It will be appreciated that the arrangement of the drainage slots may be other than as described above. Each of the drainage slots 21 shown in Figures I and 2 could be divided into two or three or more smaller slots. The slots need not extend transversely, they could extend longitudinally. They need not be rectangular, they could be round or oval or any other suitable shape.

9

Claims

1. A drainage system comprising a trench extending into the ground firom ground level with a plurality of channel members laid in end-to-end abutting relationship along the trench and a plurality of lid members laid in end- to-end abutting relationship over the channel members to close the channel members, each lid having a cover portion below ground level and at least one projection extending from the lid to ground level, the or each projection including a drainage hole at ground level for the passage of fluid through the lid, and the at least one projection of one lid being spaced from the at least one projection of the next adjacent lid, concrete covering the lids and surrounding the projections to ground level leaving the drainage holes exposed.

2. A system according to claim I wherein the lids are formed separately fi7om the channel members and are bonded thereto.

3. A system according to claim I or claim 2, wherein a series of side-byside but spaced projections are provided, the series extending along the lid in a direction generally parallel to the length of the channel.

4. A system according to claim 3, wherein each projection and the associated hole are generally rectangular in cross-section.

5. A system according to claim 4, wherein each cross-section has a longer dimension extending in a direction normal to the length of the channel.

6. A system according to any one of claims I to 5, wherein the or each hole is, at an end thereof remote from the channel, closed by a removable cap.

7. A system according to claim 6, wherein the or each cap is of a plastics material.

8. A system according to any one of claims I to 7, wherein the lid carries reinforcing means for co-operation with concrete poured around the assembly.

9. A system according to claim 8, wherein said reinforcing means comprise a plurality of metal reinforcing bars.

10. A system according to claim 9, wherein said reinforcing bars are welded together to form a mesh.

11. A system according to claim 10, wherein the mesh is generally flat, lies in a plane parallel to the plane of the lid and projects laterally beyond both side edges of the lid.

12. A system according to any one of claims I to 11, wherein the channel and the lid are formed from fibre-rein forced concrete.

13. A drainage system substantially as hereinbefore described with reference to the accompanying drawings.

14. A method of forming a drainage system substantially as hereinbefore described with reference to the accompanying drawings.

14. A method of forming a drainage channel using a plurality of channel members and a plurality of lid members, each lid having a cover portion and at least one projection extending from the lid, the or each projection including a drainage hole for the passage of fluid therethrough, the method comprising preparing a trench, laying the plurality of channel members in end-to-end abutting relationship along the trench, the channel members being closed by the plurality of lid members, the cover portions of the lids being below ground level and the drainage holes being at ground level with the at least one projection of one lid being spaced from the at least one projection of the next adjacent lid, and then pouring concrete to cover the lids and surround the projections to ground level leaving the drainage holes exposed.

15. A method of forming a drainage channel substantially as hereinbefore described with reference to the accompanying drawings.

I;LI Amendments to the claims have been filed as follows CLAIMS 1 A drainage system comprising a trench extending into the ground from ground level with a plurality of channel members laid in end-to-end abutting relationship along the trench and a plurality of lid members laid in endto-end abutting relationship over the channel members to close the channel members, each lid having a cover portion below ground level and at least one projection extending from the lid to ground level, the or each projection including a drainage hole at ground level for the passage of fluid through the lid, and the at least one projection of one lid being spaced from the at least one projection of the next adjacent lid, concrete covering the lids and surrounding the projections to ground level leaving the drainage holes exposed.

2. A system according to claim I wherein the lids are formed separately from the channel members and are bonded thereto.

12. A system according to any one of claims I to 11, wherein the channel and the lid are formed from fibre-reinforced concrete.

13. A method of forming a drainage system using a plurality of channel members and a plurality of lid members, each lid having a cover portion and at least one projection extending from the lid, the or each projection including a drainage hole for the passage of fluid therethrough, the method comprising preparing a trench, laying the plurality of channel members in end-to-end abutting relationship along the trench, the channel members being closed by the plurality of lid members, the cover portions of the lids being below ground level and the drainage holes being at ground level with the at least one projection of one lid being spaced from the at least one projection of the next adjacent lid, and then pouring concrete to cover the lids and surround the projections to ground level leaving the drainage holes exposed.