GB2350133A

GB2350133A - Drainage unit with removable insert pipe and replaceable filter.

Info

Publication number: GB2350133A
Application number: GB9911288A
Authority: GB
Inventors: Douglas John Ayres
Original assignee: Individual
Current assignee: Individual
Priority date: 1999-05-14
Filing date: 1999-05-14
Publication date: 2000-11-22
Anticipated expiration: 2019-05-14
Also published as: GB2350133B; GB9911288D0

Abstract

A drainage unit for conducting water from ground behind eg a retaining wall or tunnel comprises a sleeve 2 secured in a cavity 1 in the retaining wall, an insert pipe 3 bearing a filter 4 that may be removed to leave a clear hole for the purposes of inspection, sampling, or injection. The filter may be removed from the insert pipe for replacement. A detachable flexible conduit pipe 9 may be connected to the drainage unit via elbow 5 or cam coupling (15, figure 2) for the conduction of water from the wall directly to a drain.

Description

2350133 MAINTAINABLE DRAIN This invention is concerned with a replaceable

maintainable drainage assembly fitted through a structure such as a tunnel wall or a retaining wall in order to remove water.

Existing drainage systems vary from a weephole bored through the structure to the ground behind to a complex metal or plastic filter mortared into place and connected to conduits cut into the wall and protected by metal covers or sprayed concrete. They cannot easily be removed, they reduce in efficiency as the filter becomes clogged, inaccessible voids can form, crystalline or oxidized matter can precipitate from the water; the system and the ground behind it cannot easily be inspected. In the case of railway tunnels and retaining walls the short time of access for repair and maintenance makes effective and economic treatment extremely difficult. As a result of clogging, water under pressure permeates through the brickwork or masonry and drips down causing humid conditions which cause rust and corrosion damaging the infrastructure. The stability of the structure is reduced as the water pressure rises in the ground and as void formation alters stress distribution.

If old brickwork is grouted to infill the many spaces in the joints then permanent weep holes become clogged and so a removable drainage unit is required.

An object of this invention is to provide an economic, swiftly installed, extractable, replaceable drainage device in a hole through a tunnel wall or earth retaining structure or boundary wall which can filter efficiently and permit inspection and access to the rear of the wall for ground stabilization processes. It connects in turn at the front face of the wall to easily demountable pipework conduiting water directly into the main drainage below or invert if present without wetting the highway or track beneath so that rail equipment life is greatly extended A specific example of the invention is shown in the accompanying drawing in which Figure I shows a cross-section of the drainage unit fixed in a tunnel wall and Figure 2 shows the drainage unit with an instantly demountable coupling of the cam type as an alternative connection.

Accordingly the invention comprises a fixed sleeve 2 which is bonded, mortared or force fitted 7 into a cavity or drillhole 1. An insert pipe 3 passes through the sleeve 2 and has a filter end 4 whose length may be varied according to ground conditions. The face end of the insert pipe 2 is enlarged I I so that it can be pulled quickly from the sleeve, and cannot become lost. in the sleeve or the drillhole or the ground behind the w all.

The sleeve is held in position by the provision of a nut 6 or a toroid ring to fill the annular space between sleeve and drillhole.

A threaded socket 12 is screwed over the face end of the sleeve 2 to receive a male threaded elbow 5 which holds the end of the insert pipe in position. An optional washer 10 can be added to improve the fit.

The filter end 4 is preferably a tube of porous sintered polyethylene whose external diameter equals the bore of the insert pipe so that a simple push fit suffices without the need of bonding cement.

The size of particle transported by ground water varies upwards from clay suspensions below 2 microns and to cope with sizes likely to settle from water at drainage velocity the filter should hold back medium silt above 30 microns as a filter with a smaller void would have too low a permeability; few particles greater than 250 microns would be carried and deposited at this velocity.

At the other end of the elbow is a socket 13 into which is inserted the conduit pipe 9 with an enlarged end held in place by a male threaded pipe nipple 14. The nipple is placed initially on the end of the pipe which is subsequently heated to provide the enlargement. The other end of the conduit pipe is uncoiled to lead to the drain or into a larger pipe holding several conduit pipes.

At any time the socket I I and elbow 5 may be removed and the insert pipe taken out for replacement or for inspection with an endoscope or for grouting. The straight sleeve 2 permits a rod to be inserted to crack grout soon after it has set to permit water to flow again.

The conduit pipe is held and supported against the wall by bolted clips or by passing through a large pipe firmly fixed to the wall; this is in order to prevent movement of the conduit pipe under wind forces and vibration caused by the passage of high speed vehicles.

As an alternative the socket 12 may be replaced by an instant cam coupling 14 having a standard female thread such as a pneumatic hose coupling and the elbow 5 may carry a similar coupling. The enlarged end 11 of the insert pipe will locate in the cam coupling 14 to enable swift renewal of the insert as before.

The threaded end 8 of the sleeve permits grout hoses, temporary cocks or water hose to be attached for grout injection'for water tests. Water can be injected to establish better flow paths for subsequent drainage.

The filter end 4 may alternatively be made of porous ceramic or of a piece of geotextile cloth of suitable permeability and porosity which is rolled and inserted in the insert pipe. Instead of a filter end 4, filtering may be achieved by replacing the washer 10 with a disc made of geotextile filter material across the end of the sleeve. The filter end 4 however presents a large area for filtering and water flow.

Water flow from the lower end of tile conduit pipe may be compared to that emerging from the insert pipe when disconnected to indicate possible blockage of the conduit pipe and any need for replacement. The upper end of the conduit pipe may alternatively be provided with a conventional nut and union end to screw on to a reducing adaptor nipple fitted into the elbow.

The advantage of this invention is that any part of the drainage path from the rear of the wall to the entry into the existing carrier drainage of the structure can be examined and maintained quickly at any time subject to access when traffic circulation is restricted.

I CLAM I. A drainage unit comprising a fixed sleeve and a removable insert pipe and a connected conduit pipe whereby the sleeve is installed in an aperture or drilled hole in the wall of a structure and the removable insert pipe bears a replaceable filter and the conduit pipe, which is detachable from the fixed sleeve, extends to an existing drainage system at the base of the structure to deliver water without saturating the ground, highway or track below or the face of the structure.

Claims

2. A drainage unit according to Claim I where the sleeve is of metal or

rigid plastic or elastomeric material.

3. A drainage unit according to Claim I where the external surface of the fixed sleeve bears welded, bonded or screwed elements or a flat or toroidal band or tube to bridge the annular space between the sleeve and drillhole.

4. A drainage unit according to Claim I where the removable insert pipe of plastic metal or elastomer is enlarged at its front end.

5. A drainage unit according to Claim 4 where the insert pipe carries at its back end a porous filter made of sintered polyethylene, sintered metal or porous ceramic or a geotextile.

6. A drainage unit according to Claim I where the filter is a porous geotextile disc at the front end of the insert pipe.

7. A drainage unit according to Claims 5 and 6 where the void or apparent pore size of the porous filter has a dimension between 30 and 250 microns.

8. A drainage unit according to Claim I where a hydraulic cementitious, bituminous or resinous bonding mortar fills part of the annular space between the sleeve and the drillhole and extends to surround the sleeve to bond it to the front face of the wall.

9. A drainage unit according to Claim 1 where an elbow or bend is attached to the fixed sleeve by screwing or clipping to hold in. turn the end of a conduit pipe.

10. A drainage unit according to Claim 9 in which the conduit pipe is provided with an enlarged end to locate in the pipe fitting which is screwed in to the elbow.

11. A drainage unit according to Claim 9 where the conduit pipe is provided with a spigot and union nut fitting to attach to the elbow and its threaded male adaptor.

12. A drainage unit according to Claim 1 wherein the conduit pipe delivers directly into the drainage system of the adjacent infrastructure without loss of water on to the surrounding highway, track or ballast.

13. A drainage unit where the conduit pipe passes along with conduit pipes from other drillholes into a larger pipe delivering into the infrastructure drainage system.

14. A drainage unit according to Claims 9, 10, 11 or 12 where the conduit pipe is held and supported against the wall by a fixed rigid clip.

15. A drainage unit substantially as described herein with references to Figs 1 and 2 of the accompanying drawing.

Amendments to the claims have been filed as follows CLAIMS 1. A drainage unit for the wall of a tunnel or of a structure comprising a fixed sleeve containing a removable insert pipe whereby the fixed sleeve is installed in an aperture or drilled hole in the wall of the structure and the removable insert pipe bears a replaceable filter.

2. A drainage unit according to Claim I where a conduit pipe is attached to and can simply be detached from tile fixed sleeve and carries water to an existing drainage system at the base of the structure.

I A drainage unit according to Claims I and 2 where the sleeve is of metal or rigid plastic or elastonieric material.

4.. A drainage unit according to Claim I where the external surface of the fixed sleeve bears welded, bonded or screwed elements or a flat or toroidal band or tube to bridge the annular space between the sleeve and drillhole.

5. A drainage unit according to Claim I where the removable insert pipe of plastic metal or elastomer is enlarged at its front end.

6. A drainage unit according to Claims I or 2 where lie removable insert pipe bears a lock nut or PLIshlock fastener at its front end.

7. A drainage unit according to Clairn 4 where the insert pipe carries at its back end a porous filter made of sintered polyethylene, sintered metal or porous ceramic or a geotextile.

8. A drainage unit according to Claim I where the filter is a porous geotextile disc at the front end of the insert pipe.

9. A drainage unit according to Claims 7 and 8 where the void or apparent pore size of the porous filter has a dimension between 30 and 250 microns.

10. A drainage unit according to Claim I where a hydraulic cementitious, bituminous or resinous bonding mortar fills part of the annular space between the sleeve and the drillhole and extends to surround the sleeve to bond it to the front face of the wall.

7 11. A drainage unit according to Claim 1 where an elbow or bend is attached to the fixed sleeve by screwing or clipping to hold in turn tile end of a conduit pipe.

12. A drainage unit according to Clanii 11 where the elbow or bend is any plumbing coupling which clamps over the external diameter of the end of the fixed sleeve to seal it by a push or screwed fit.

11 A drainage unit according to Cl-aim 11 in which the conduit pipe is provided with an enlarged end to locate in the pipe fitting which is screwed in to the elbow.

14. A drainage unit according to Claim 11 where the conduit pipe is provided with a spigot and union nut fitting to attach to the elbow and its threaded male adaptor.

15. A drainage unit according to Claim 1 wherein the conduit pipe delivers directly into the drainage system of the adjacent infrastructure without loss of water on to the surrounding highway, track or ballast.

16. A drainage unit where the conduit pipe passes along with conduit pipes from other drillholes into a larger pipe delivering into the infrastructure drainage system.

17. A drainage unit according to Claims 13, 14, 15 or 16 where the conduit pipe is held and supported against the wall by a fixed rigid clip.

18 A drainage unit substantially as described herein with references to Figs 1 and 2 of the accompanying drawing.