GB2301132A

GB2301132A - Drainage unit

Info

Publication number: GB2301132A
Application number: GB9518975A
Authority: GB
Inventors: Royston Wayne Burnett-Jones
Original assignee: COOPER CLARKE GROUP PLC
Current assignee: COOPER CLARKE GROUP PLC
Priority date: 1995-09-15
Filing date: 1995-09-15
Publication date: 1996-11-27
Anticipated expiration: 2015-09-15
Also published as: GB2301132B; ATE256789T1; EP1143071B1; HK1007076A1; DE69631983D1; DE69631983T2; GB9518975D0; EP1143071A1; CA2185476C; EP0763631B1; EP0763631A1; HK1004005A1; DE69631101D1; ATE262620T1; DE69631101T2; CA2185476A1

Abstract

A drainage unit (10) comprises first and second apertures (15,16) for allowing water to pass into the interior of the drainage unit. The first and second apertures are located such that, in use, the first aperture (16) is at a greater height than the second aperture (15). When the drainage unit is disposed at the side of a road, the first aperture is able to drain surface water from the road surface, and the second aperture is able to drain sub-surface water from within the road construction. The first aperture is not in direct fluid communication with the second aperture, so that surface water entering the drainage unit through the first aperture is prevented from passing back into the road construction through the second aperture. <IMAGE>

Description

1 Drainage Unit 2 -:) c --- This invention relates to a drainage unit

suitable for use in an elevated structure such as a bridge or a multi-storey car park. Figure 1 shows a typical drainage unit 1. This is designed to be placed at the side of a road on a bridge so that the road surface at the edge of the road is level with the bottom edge of the holes 2. The camber of the road causes water to run off the road surface and pass into the drainage unit through the holes 2. The hole 3 in the end wall allows water to pass into an adjacent unit. Units are placed next to one another to produce a drain running the length of the bridge.

Figure 2 shows a cross-section through a typical bridge. A concrete deck 4 is covered with a waterproof membrane 5 and a layer of red sand asphalt 6 to protect the waterproof membrane. The road is surfaced with an asphalt base course 7A and an asphalt wearing course 7B. The asphalt layers will not be watertight, and some water will permeate through them. The red sand asphalt layer is less permeable to water than the other asphalt layers, and water will accumulate in the asphalt layers 7A, 7B. This water will hereinafter be referred to as "subsurface water".

2 If subsurface water continues to accumulate the asphalt layers will eventually become saturated; water will then appear on the road surface, causing a driving hazard. In winter, repeated freezing and thawing of the subsurface water will damage the road. Furthermore, when a vehicle passes along the road the weight of the wheel will cause a "pumping action" on the subsurface water in the road construction. A "bow wave" 8 is pushed through the asphalt layers 7A, 7B towards the side of the road. The water cannot enter the drainage unit 1, and it is deflected upwards by the drainage unit, as indicated by the arrows. This causes rapid deterioration of the road surface, as the water will tend to carry the binding particles contained in the asphalt upwards out of the asphalt layers and deposit them as silt 9 on the road surface. Such deposits of silt form another driving hazard.

It is possible to make some allowance for the relief of subsurface water by leaving small gaps beneath and/or between adjacent edge kerbs or drainage units to provide a drainage path. Although these gaps initially provide a drainage path they quickly silt up and block the passage of water.

Figure 3 shows a drainage unit 11 in which some holes 2' have a V-shaped lower edge. The unit is positioned so that the V-shaped portion of the holes are below the road surface, so subsurface water within the asphalt 3 layers can pass through the holes into the drainage unit.

This drainage unit is not satisfactory. If the V-shape part of the holes is shallow it will not collect all the subsurface water from the asphalt layers. If the V-shaped part extends to the bottom of the drainage unit, however, it will then be possible for water to drain off the road surface, enter the drainage unit through the top part of the holes and pass back into the road through the lower part of the holes.

GB-A-2 257 734 discloses a subsurface bridge drain unit which has a perforated collection chamber. This is buried in the road, so that the perforations in the collection chamber are in the lower part of the asphalt base course 7A. The collection chamber has an outlet which passes through the bridge deck. Subsurface water enters the collection chamber and is drained away through the outlet.

This drainage unit will not drain surface water effectively, so it therefore necessary to provide conventional drains as well as the subsurface drainage unit. Furthermore, each subsurface drainage unit requires a hole throughthe bridge deck which will weaken the bridge.

4 The present invention provides a drainage unit having at least one aperture for collecting surface water and at least one aperture for collecting subsurface water.

This drainage unit is able to collect both surface water and subsurface water from a road.

In a preferred embodiment the drainage unit comprises two channels, one channel being in fluid communication with the aperture(s) for collecting surface water and the other channel being in fluid communication with the aperture(s) for collecting subsurface water. In a particularly preferred embodiment the two channels are not in direct fluid communication with one another.

The surface water will pass through the upper aperture(s) into one channel of the drainage unit, and will be drained away. It will not pass back into the road construction layers. The subsurface water will pass through the lower aperture(s) into the second channel, and will be drained away.

A preferred embodiment of the present invention will now be described by way of example with reference to the accompanying Figures in which:

Figure 1 is a perspective view of a known drainage unit; Figure 2 shows a cross-section of a road; Figure 3 is a perspective view of another known drainage unit; Figure 4 is a schematic view of a drainage unit according to one embodiment of the present invention; Figure 5(a) shows components of another drainage unit of the present invention; Figure 5(b) shows the drainage unit of Figure 5(a) in its assembled state; Figure 5(c) shows components of another drainage unit of the present invention; Figure 6 shows a further embodiment of the present invention; Figure 7 is a cross-section of a further embodiment of the present invention; and Figure 8 is a cross- section of a further embodiment of the present invention.

Figure 4 shows a drainage unit 10. The unit is provided with a wall 13 which defines a closed channel 14. Internal water passes from the road through the lower apertures 15 into the channel 14, as a result either of natural drainage or of a "bow wave" caused by a vehicle. Surface water passes through upper apertures 16 into the interior 17 of the drainage unit. This drainage unit is able to drain both surface and subsurface water from the road. The surface water cannot enter the channel 14 and so is unable to pass back into the road construction layers.

6 For ease of construction, the unit is formed of a base 11 and an cover 12. Figure 5a shows an alternative embodiment of the invention, and shows the base 111 separated from the cover 121. The cover is provided with prongs 22; when the cover is placed on the base an upper aperture is defined by a pair of adjacent prongs. as shown in Figure 5b. Figure 5(c) shows an alternative design for the cover 111 and base 12'.

The cover 12, 12' and the base 11, 111 can be made of any suitable material. In one embodiment the base is manufactured in ductile iron, which is chosen for its good finish and strength. The cover is made from a composite material, and this allows the cover to be produced in any desired colour. The cover is secured to the base by any suitable means.

Figure 6 shows an alternative base unit 1111. The channel 14 is provided with a hatch 18 which can be removed to provide access to the channel. This allows the channel to be inspected or cleaned. The cover can also be provided with a removable hatch (not shown), to avoid the need to remove the whole cover to provide access to the base. In use, it would be advisable if inspection hatches were provided every 20m or so.

The drainage unit is installed on a bedding layer of mortar 19 which has a thickness of, for example, 5mm.

7 The end face of the unit is coated with a sealant, and the unit is pushed firmly against the previous unit to make a watertight seal between the two units.

The base is provided with projections 20 at one end, and the other end is provided with complementary recesses. These projections and recesses provide interlocking between two adjacent units, which lessens the chance of a unit being displaced if it is struck by a vehicle.

Figure 7 shows a cross-section of an alternative embodiment of the present invention. The channel 14 is not closed, but is defined by a wall 20 and a ledge 21. The ledge 21 extends beyond the channel, so surface water entering the unit is directed into the interior of the unit and can not enter the channel (unless the depth of water in the interior exceeds the height of the wall 8 20). The ledge 21 is shown as being part of the base unit in Figure 7, but it could be part of the cover.

Another embodiment -s illustrated in Figure 8. The wall 131 defining the channel for subsurface water is horizontal, so that the channel for subsurface water is below the channel for surface water. This embodiment could also be realised by constructing a drainage channel for subsurface water and placing conventional drainage units (as shown in Figure 1, for example) over the channel for subsurface water to form the drainage channel for surface water.

It is not necessary 'or every drainage unit to have apertures for receiving both surface and subsurface water. For example, it would be possible to manufacture two different drainage units, one having only apertures for receiving surface water and the other having only apertures for receiving subsurface water. The drain would be formed from a combination of both units - for example, with the two units alternating with one another.

9

Claims

CLAIMS:

1. A drainage unit comprising at least one aperture for receiving surface water and at least one aperture for receiving subsurface water.

2. A drainage unit as claimed in claim 1 wherein two channels are defined within the drainage unit, one channel being in fluid communication with the aperture(s) for receiving surface water and the other channel being in fluid communication with the aperture(s) for receiving subsurface water.

3. A drainage unit as claimed in claim 2 wherein the two channels are not in direct fluid communication with one another.

4. A drainage unit wherein two channels are defined within the drainage unit, the drainage unit comprising an aperture communicating with one of the channels.

5. A drainage unit as claimed in any preceding claim and comprising interlocking means for engaging with complementary interlocking means on an adjacent drainage unit.

6. A method of draining a structure as claimed in claim 5 wherein the second drainage channel is adjacent to the first drainage channel.

6. A drainage unit substantially as herein described with reference to Figure 4 or to Figures 5a and 5b or to Figure 7 or to Figure 8.

7. A method of draining a structure comprising the steps of providing a first drainage channel for receiving surface water; and providing a second drainage channel for receiving susbsurface water.

8. A method of draining a structure as claimed in claim 7 wherein the second drainage channel is adjacent to the first drainage channel.

9. A method of draining a structure as claimed in claim 8 or 9 and further comprising the step of preventing direct fluid communication between the first and second drainage channels.

Amendments to the claims have been filed as follows JI CLAIMS:

1. A drainage unit comprising at least one aperture for receiving surface water and at least one aperture for receiving subsurface water; wherein the aperture(s) for receiving surface water is/are not in direct fluid communication with the aperture(s) for receiving subsurface water.

2. A drainage unit as claimed in claim 1 wherein two channels are defined within the drainage unit, one channel being in fluid communication with the aperture(s) for receiving surface water and the other channel being in fluid communication with the aperture(s) for receiving subsurface water, the two channels not being in direct fluid communication with one another.

3. A drainage unit as claimed in any preceding claim and further comprising interlocking means for engaging with complementary interlocking means on an adjacent drainage unit.

4. A drainage unit substantially as herein described with reference to Figure 4 or to Figures 5a and 5b,pr to Figure 7 or to Figure 8.

i p- 5. A method of draining a structure comprising the steps of providing a first drainage channel for receiving surface water through at least one aperture; providing a second drainage channel for receiving susbsurface water through at least one other aperture; and preventing direct fluid communication between the first and second drainage channels.