GB2208465A - Underground drainage - Google Patents

Abstract

A ground drain system comprises a drainage pipe 2, and a plurality of upstanding hollow pillars 6 which can drain water directly from the surrounding ground without intervening granular filter material. Each pillar has apertures 8, and is enclosed by or contains a filter medium 10 to hold back soil particles. The drainage system may be composed of individual units jointed end to end, each unit may comprise a pair of moulded plastics half shells forming the main drainage pipe and one or more integral pillars. Upward extension may be provided for the pillars. <IMAGE>

Description

UNDERGROUND DRAINAGE This invention relates to underground drainage. and in particular to subsoil drains and the like. for draining off water from the surrounding ground.

Conventionally, subsoil drains comprise slotted or perforated pipes laid in a suitable bed of granular material which acts as a collector and filter.

Recently, it has been proposed to use geotextiles mounted on a suitable support, as drainage means, the textile material (for example moulded plastics mesh) acting as a filter to permit entry of ground water from the surrounding ground.

According to the present invention, we provide drainage means comprising a drainage pipe or duct to be laid generally horizontally, and at least one upright hollow pillar defining a space communicating with the interior of the drainage pipe, and provided with one or more openings for entry of ground water. Preferably there is also provided a filter medium enclosing or contained in the pillar for permitting the flow of ground water while preventing solid particles entering the drain pipe from the ground.

With such a drainage means, the usual granular bedding material can be wholly or partly dispensed with, as the upright pillar will pick up percolating water from the surrounding ground over a range of levels corresponding to the pillar or pillars. The main pipe and pillars form an arrangement like an inverted comb.

The pillar, or the main pipe and pillar as a unit, may for example comprise a pair of shells each forming half of the circumference, fastened together to form a complete hollow pillar or drainage unit.

The pillar may be integral with the drainage pipe or may be fixed into an aperture provided or cut in the drainage pipe, generally but not necessarily in the top of the drainage pipe.

The pillar may be a tube, open or closed at its upper end. Alternatively it may be a framework surrounded by and/or enclosing the filter medium.

The pillar may be provided with pipe coupling means at its lower end for mating with one or more pipe lengths, forming the drainage pipe or duct.

With such a construction, the drainage system can be composed of ordinary commercially available pipe lengths, interconnected by the coupling means provided on the upright water intake pillars. This can simplify manufacture, stocking-and installation and thereby reduce costs.

The pipe coupling can be of any convenient kind, in particular, a sleeve comprising a pair of sockets (in line or at an angle to one another) to receive spigot ends of pipe lengths, or a sleeve comprising a pair of spigots (in line or at an angle) to fit inside the ends of the pipe lengths (which may be plain-ended or socketed). For use with bell-ended pipes, the coupling may have a socket on one side and a spigot sleeve on the other side. The coupling may be designed to couple pipes of different diameters.

The coupling may be provided with seal rings to seal against the pipe lengths. However, in subsoil drains.

perfect sealing is not essential and therefore such seals, if provided. can be of a lower standard than in sewerage and similar piping. In the case of a drainage system composed of plastics components including plastics pipe lengths. the components themselves may provide adequate sealing without additional seals being provided, because such components are commonly made to relatively close tolerances and the resulting close fit between the pipe lenghts and coupling may provide adequate sealing against the entry of soil particles.

The pipe coupling may be adapted to mate with the pipe lengths by a push fit.

Alternatively, the coupling may be split longitudinally, comprising a pair of opposed shells, which in use are fitted together around the ends of the pipe lengths to be coupled and are secured in any convenient manner, for example by snap fastenings on the the respective shells or by fastenings bands. The fastening means need only be strong enough to hold the shells in position during back-filling. The shells may for example comprise a lower shell in the form of a half cylinder, and an upper shell integral with the pillar.

Alternatively, the coupling sleeve and pillar as a unit, may for example comprise a pair of shells each forming half of the circumference, fastened together to form a complete hollow pillar or drainage unit.

The filter medium may be a so-called geotextile, of a mesh size suitable to prevent passage of ground particles without becoming clogged or unduly resisting the flow of ground water. Such materials are becoming quite well known. They may comprise woven or non-woven material, or moulded or extruded material, of appropriate porosity, for example so-called needle punched geotextiles. According to one specification, the material should be so selected that the 95% level of its hole size distribution corresponds to the 50% dimension of the particle size distribution of the surrounding soil.

A textile filter medium can be used either outside or inside the pillar. Alternatively or in addition, the filter medium may comprise a filter packing inside the pillar in the water flow path to the interior of the drainage pipe. In this case the filter medium may for example be a porous open-cell plastics foam material.

The pipe lengths can be of any convenient material, for example extruded or inJection moulded plastics such as uPVC, polypropylene, fired clayware, glazed or unglazed, concrete, asbestos, and so on. As already mentioned, they may be plain-ended, or may have socket or bell ends.

The invention will be further described with reference to the accompanying drawings, which show schematically parts of ground or subsoil drains embodying the invention. In the drawings: Figures 1 to 4 respectively show, in perspective, different embodiments of the present invention.

Figure 1 shows a drainage pipe 2, to be laid in a trench with or without suitable bedding material, at an appropriate angle of fall to carry away ground water.

This pipe can be made of any suitable material, for example fired clay or extruded plastics. It can have any desired profile in cross-section, in particular circular as illustrated.

In the upper surface of the drainage pipe is an aperture or apertures 4. This aperture can be provided in the pipe at the factory, or can be cut on site.

In the opening 4 is fitted an upright pillar or column 6, secured in the aperture in any convenient way for example by integral or separate clips, by solvent welding, by an adhesive, or by a frictional push fit for example in a grommet fitted in the opening. The walls of the hollow pillar are provided with a multiplicity of holes, slots or other openings 8, and the entire pillar is enclosed in a sheath 10 of a plastics textile or mesh filter medium, in particular a geotextile as already described.

The upper end of the pillar is closed, by end walls integral with the rest of the pillar, or by a separate end cap. The latter is preferable, so that an extension of the pillar can be fitted in place of the end cap to give greater depth of drainage.

In use, the pipe 2, with a plurality of the pillars1 is laid in a trench optionally with suitable bedding material to admit ground water, which enters the pillars through the apertures 8 and is then carried away through the main pipe 2. The textile sheath 10 acts to filter out any solid particles which may have penetrated the backfill in the trench.

Successive lengths of the main pipe 2 are jointed together, for example by pipe coupling sleeves, or by spigot and socket joints formed integrally with the pipe ends, in conventional manner with a spigot at one pipe end and a matching socket at the other pipe end, and suitable seals for the joints.

In another possible construction, lengths of extruded plastics (uPVC) pipe are provided with periodic holes or slots. Separately moulded pillars are mounted on the pipe lengths over the holes or slots1 being provided with flanges, strapped or clipped to the pipe length either with integrally moulded elements or by worm screw clip arrangements.

Figure 2 shows another embodiment of the invention, in which the main pipe and pillar are moulded integrally of plastics material. This product comprises individual lengths of main pipe, each provided with one or more integral pillars1 the main pipes being jointed together end to end, so that the assembly looks rather like a comb set upright on its back. Each unit of the drainage system, comprising a length of main pipe and one or more integral pillars, is assembled from a pair of mating half shells of moulded plastics material, which are fitted and fastened together face to face to form the main pipe and pillars. The shells meet in a vertical plane at a joint line 12, where they are secured together by clipping, adhesive or solvent welding, or in any other convenient way. The shells have internal pins or struts 14 to enhance the strength and rigidity of the assembly.It will be seen that these are arranged in pairs, with one pin or strut of each pair integral with a respective one of the half shells. Preferably, the half shells are identical with each other, for ease of manufacture and storage and simplicity of assembly; the pins or struts will then be placed asymmetrically in each half shell.

The main pipes are jointed together end to end by integral jointing means, for example by a simple push fit, or by separate coupling sleeves.

Extension pieces for extending the pillars upwards may be provided1 to be seated on the upper ends of the pillars. End caps for closing off the upper ends of the pillars will also be provided; these may be separate from or integral with the pillars.

The pillars of the drainage units shown in Figure 2 are provided with a filter sheath as in the case of Figure 1.

Typically, the drainage unit may be made in a length of one meter, with a pillar or pillars 500 mm or 600 mm high, with a cross-section of, for example, 150 by 25 mm.

The filter sheath may fit the pillar closely or may be relatively loose. It can be attached to the pillar, or secured to the main pipe at or around the opening 4 (Figure 1), or left unfastened, as it will be held in place by the weight of the surrounding ground or bedding material.

Figure 3 shows a length of drainage pipe 22, to be laid in a trench with or without suitable bedding material, at an appropriate angle of fall to carry away ground water.

This pipe can be made of any suitable material, for example fired clay or extruded plastics. It can have any desired profile in cross-section, in particular circular as illustrated.

At each end, the pipe length is fitted into one of the sockets, at one side of a pipe coupling sleeve 23 of injection moulded plastics material. The coupling sleeve may be an integral moulded cylindrical sleeve, but in the illustrated embodiment it comprises a lower half shell 4 and an upper half shell 25, which in use are fitted together about the end of the pipe length.

These half shells are held together by suitable fastening means (not shown), and for convenience, may be united along one side, by an integral plastics hinge.

Integral with the upper half shell 25, is an upright pillar or column 26. This may be integrally moulded with the upper half shell, or may be secured into an aperture in the upper half shell any convenient way for example by integral or separate clips, by solvent welding, by an adhesive, or by a frictional push fit for example in a grommet fitted in the opening. The walls of the hollow pillar are provided with a multiplicity of holes, slots or other openings 8, and the entire pillar is enclosed in a sheath 10 of a plastics textile or mesh filter medium, in particular a geotextile as already described.

The upper end of the pillar is closed, by end walls integral with the rest of the pillar, or by a separate end cap. The latter is preferable, so that an extension of the pillar can be fitted in place of the end cap to give greater depth of drainage.

In use, the pipe lengths 22, coupled together by couplings 23 to provide a plurality of the pillars, are laid in a trench optionally with suitable bedding material to admit ground water, which enters the pillars through the apertures 8 and is then carried away through the main pipe 22. The textile sheath 10 acts to filter out any solid particles which may have penetrated the back fill in the trench. The assembled drainage system looks rather like a comb set upright on its back.

The pipe coupling sleeves may have a spigot and a socket to joint pipes provided with a spigot at one pipe end and a matching socket at the other pipe end.

Suitable seals may be provided for the joints between the pipe ends and couplings.

Figure 4 shows another embodiment of the invention, in which the pipe coupling and pillar are moulded integrally of plastics material. Each unit comprising a pipe coupling and integral pillar, is assembled from a pair of mating half shells 27. 29 of moulded plastics material, which are fitted and fastened together face to face to form the coupling and pillar. The shells meet in a vertical plane at a joint line 32, where they are secured together by clipping, adhesive, solvent welding, or in any other convenient way. The shells have internal pins or struts 14 to enhance the strength and rigidity of the assembly. It will be seen that these are arranged in pairs, with one pin or strut of each pair integral with a respective one of the half shells.

Preferably, the half shells are identical with each other, for ease of manufacture and storage and simplicity of assembly; the pins or struts will then be placed asymmetrically in each half shell.

The pipe coupling, and the pillar if integral therewith, are preferably made of injection moulded plastics material, for example polypropylene.

Extension pieces for extending the pillars upwards may be provided, to be seated on the upper ends of the pillars. End caps for closing off the upper ends of the pillars will also be provided, or may be moulded integrally.

The pillars of the drainage units shown in figure 4 are provided with a filter sheath 10 as in the case of figure 3.

Typically, the drainage system may have a pillar spacing of about one meter, with pillars 500 mm or 600 mm high, with a cross-section of, for example, 150 by 25 mm.

The filter sheath may fit the pillar closely or may be relatively loose. It can be attached to the pillar, or secured to the coupling pipe at or around the pillar or left unfastened, as it will be held in place by the weight of the surrounding ground or bedding material.

In all the embodiments, the filter sheath may be factory fitted, or fitted on site.

Instead of or in addition to the external filter sheath, the pillar may contain a packing of porous filter medium, for example a plastics textile or mesh, or a porous cellular mass.

The pillars described are hollow tubes.

Alternatively, the pillar may comprise one or more sheets of material, for example plastics, provided with projections on one or both sides so as to hold a layer of filter medium away from the sheet or sheets and thereby define an enclosed space accessible from the ground only through the filter layer, this space in turn communicating with the interior of the main drainage pipe 2.

In the described embodiments, each pillar communicates directly with the interior of the drain pipe through the top of the latter or through the top of a coupling. In an alternative arrangement, the upright pillar may communicate with the interior of the drain pipe or coupling, in the lower region of the pipe or coupling. For example, there may be a wall between the lower end of the pillar and the top of the drain pipe or coupling, and a pipe extending downwards from the lower end of the pillar, on the outside of the drain pipe or coupling, to an opening in the side wall of the drain pipe or coupling. Such an arrangement provides a little extra pressure head, corresponding to the difference in height between the top of the drain pipe or coupling, and the actual point of communication between the pillar and the drain pipe or coupling.

The described constructions can provide a cheap, simple and effective ground drainage system.

Claims (7)

Claims

1. Drainage means comprising a drainage pipe or duct to be laid generally horizontally, and at least one upright hollow pillar defining a space communicating with the interior of the drainage pipe, and provided with one or more openings for entry of ground water.

2. Drainage means as claimed in claim 1, provided with a filter medium enclosing and/or contained in the pillar or pillars, for permitting the flow of ground water while preventing solid particles entering the drain pipe from the ground.

3. Drainage means as claimed in claim 1 in which the upright hollow pillar has at its lower end a pipe coupling sleeve for mating with pipe lengths forming said drainage pipe or duct.

4. Drainage means as claimed in claim 1, 2, or 3 comprising of respective shells disposed face to face, each shell comprising one half of a length of said drainage pipe or said coupling sleeve together with one half of at least one said pillar.

5. A drainage component, comprising a pipe coupling sleeve, and a pillar extended laterally therefrom, to be installed upright in use, the said pillar being hollow and defining a space communicating with the interior of the coupling sleeve, for communicating thereby with pipes coupled to the coupling sleeve, the pillar being provided with one or mor openings for entry of ground water.

6. Drainage means, substantially as herein described with reference to figure 1 or figure 2 of the drawings.

7. Drainage means, substantially as herein described with reference to figure 3 or figure 4 of the drawings.