Drain system, as well as sleeve for such drain system

Abstract

 A drain system, comprises a perforated pipe (1) and a filter sleeve (5) surrounding the perforated pipe (1). The filter sleeve (5) comprises a support structure (7) having an outer surface and an inner surface and defining openings (11) which extend between said outer surface and inner surface, as well as at least one porous sheet (6,8) supported by said support structure (7). The support structure (7) comprises e.g. an open cell structure.

Description

[0001] The invention is related to a drain system comprising a perforated pipe and a filter sleeve surrounding the perforated pipe. Such a drain system is widely known, and is primarily used for draining soil which has a relatively high water content. The draining is carried out so as to control the groundwater level, or for other purposes such as cleaning polluted ground.

[0002] An example of such a drain system is disclosed in EP-A-29713.According to another possibility, the filter sleeve consists of a fiber material, for instance coconut fibers. The purpose of this sleeve is to collect particles which are present in the groundwater, and to establish a specific particle size distribution through the thickness of the sleeve. Once a specific pattern of particles has settled through the thickness, a desired filter action is obtained. The larger particles, which bring the risk of choking the perforated pipe, are prevented from entering the drain system whereby a long-term proper draining action can be ensured.

[0003] The filter sleeve thus plays an important role in maintaining the desired particle distribution pattern around the perforated pipe. However, materials such as coconut fibers will generally decompose after some time, which causes loss of support for the particle distribution pattern. In case movements occur in the soil, said pattern is readily lost whereby the desired filter action is no longer ensured. As a result, the perforated drainage pipe runs the risk of being choked.

[0004] Furthermore, drain systems are known consisting of a perforated pipe surrounded by a tubular geotextile sheet. The geotextile prevents particles from a certain size upwards to reach the perforated pipe. Liquid and smaller particles are able to pass the geotextile and may enter the perforations in the pipe for discharge. Ideally, the full surface of the geotextile is available for such filter action. This provides a large filter capacity. The perforated pipe in question is preferably a corrugated pipe, wherein the perforations are situated in the valleys of the corrugations. However, as soon as the geotextile is pressed against the pipe by the earth pressure, the filter action of the geotextile is limited to the spots where it overlies the perforations in the pipe. Thereby, the area of the geotextile which is available for filtration is severely limited, as a result of which the design filter capacity cannot be ensured in the long run.

[0005] The object of the invention is therefore to provide a drain system of the type described before which is more stable in the course of time, in such a way that the long term proper function and design capacity thereof can be ensured. Said object is attained in that the filter sleeve comprises an support structure having an outer surface and an inner surface and defining openings which extend between said outer surface and inner surface, as well as at least one porous sheet supported by said support structure.

[0006] The support structure has a certain rigidity, in such a way that the sheet(s) supported thereby can be held in the desired position with respect to the pipe so as to ensure long term draining capacity. Any particles which pass through the sheet(s) of the drain system, are collected within the pipe for further discharge. As said support structure can be manufactured form e.g. plastics, it is ensured that a long term stability of the drain system is ensured.

[0007] The support structure which is used in the drain system according to the invention can be carried out in several ways. It may have an open cell structure. Such structure can be obtained in many different ways, such as by perforating a plate. Preferably, the tubular grid comprises intersecting and/or welded strips the width direction of which is generally radially oriented with respect to the pipe. Such array of strips may take the form of a honeycomb structure. As an example of an array of strips which is particularly suitable for the drain system according to the invention, reference is made to WO-A-2006/0106101. Said publication discloses a honeycomb structure which consists of plastic strips which are extruded simultaneously in a parallel fashion and which are subsequently adhered to each other locally. By extending the array of strips thus formed in transverse direction, a honeycomb-like structure is obtained which is perfectly fit to serve as a grid for the present sleeve.

[0008] The process of forming the desired particle distribution is enhanced by the cells of the honeycomb structure. The cells are bordered by the sheets, in such a way that a stable package of particles is obtained. Preferably, the porous sheets comprise a geotextile. The properties of the geotextile covering the outer surface of the grid may be different from the properties of the geotextile covering the inner surface.

[0009] The porous sheet may be positioned at different locations with respect to the support structure. For instance, the porous sheet may be positioned on the inner surface of the support structure. Also a position on the outer surface of the support structure is possible. Both the outer surface and the inner surface may be covered by a respective porous sheet. A position within the support structure is also possible. For instance, a porous sheet may be positioned between two support structures which surround each other, e.g. between coaxial support structures.

[0010] The perforated pipe may be a corrugated pipe, although pipes having a constant cross section in longitudinal direction may be used as well in the drain system according to the invention. Also, the perforated pipe may be circular, square, rectangular, triangular. Other shapes with more angles are possible as well.

[0011] Further advantages may be obtained in case the grid and the porous sheets consist of the same material, such as polypropylene or PVC. The porous sheets may comprise a woven, nonwoven, knitted or braided material.

[0012] The invention is also related to a filter sleeve for use in the drain system described before, comprising a support structure having an outer surface and an inner surface between which openings extend, as well as at least one porous sheet supported by the support structure.

[0013] The invention will furthermore be described with reference to an example shown in the figures.

Figure 1 shows the longitudinal section to the upper part of the drain system according to the invention.

Figure 2 shows a cross-section according to II of figure 1.

Figure 3 shows the view in perspective and in cross-section, partly taken away, of the drain system.

Figure 4 shows the longitudinal section IV-IV according to figure 3.

[0014] The drain system shown in figures 1, 2 and 3 consists of the corrugated pipe l, which is known per se, and which has ring parts 2 with a relatively large diameter and ring parts 3 with a relatively small diameter. These ring parts 2, 3 provide the corrugated pipe 1 with a certain flexibility, which is desirable when laying the corrugated pipe according to bends. The ring parts 3 with relatively small diameter or valleys are provided with openings 4 through which water from the surrounding soil may penetrate into the corrugated pipe 1 for removal.

[0015] The drain system furthermore consists of the filter sleeve 5 which has been provided around the corrugated pipe 1 and which provides a filter action. In this way, it is prevented that the openings 4 in the corrugated pipe 1 become blocked by particles larger than said openings 4. This filter action is obtained by a mechanism according to which the filter sleeve, which has internal open spaces, collects relatively small particles over time during the flow of water into the corrugated pipe 1. This mechanism, which is known per se, leads to the collection of relatively small particles on the radially innermost part of the filter the sleeve. Gradually, larger and larger particles are collected and packed at a radially large a distance, in such a way that particles which are too large for penetrating the openings 4 in the corrugated pipe 1 are kept outside.

[0016] The filter sleeve 5 according to the invention consists of an inner geotextile layer 6, an outer geotextile layer 8 as well as grid like or honeycomb like support layer 7. This honeycomb like layer 7 generally consists of plastic strips 9, 10 Which are adhered to each other which cross each other. These strips 9, 10 define apertures 11 which form the spaces within which the packing 12 of particles described before can be obtained, as shown in figure 4. As mentioned before, relatively fine particles 13 contact near the inner sheet 6, whereas relatively course articles 14 collect more to the outside of the outer sheet 8.

[0017] The drain system as described before is accommodated within a prepared trajectory, such as a groove, in a bottom to be drained. The filter sleeve ensures that particles above a certain size barred from entering the corrugated pipe, in such a way that the long term drain action can be ensured.

Claims

1. Drain system, comprising a perforated pipe (1) and a filter sleeve (5) surrounding the perforated pipe, characterized in that the filter sleeve comprises a support structure (7) having an outer surface and an inner surface and defining openings (11) which extend between said outer surface and inner surface, as well as at least one porous sheet (6, 8) supported by said support structure (7).

2. Drain system according to claim 1, wherein the support structure (7) comprises an open cell structure.

3. Drain system according to claim 1 or 2, wherein the support structure (7) comprises intersecting and/or welded strips (9, 10) the width direction of which is generally radially oriented with respect to the pipe.

4. Drain system according to any of the preceding claims, wherein the support structure (7) comprises a honeycomb structure.

5. Drain system according to any of the preceding claims, wherein the porous sheet (6, 8) comprises a geotextile.

6. Drain system according to any of the preceding claims, wherein the outer surface of the support structure (7) is covered by a porous sheet (8).

7. Drain system according to any of the preceding claims, wherein the inner surface of the support structure (7) is covered by a porous sheet (6).

8. Drain system according to any of the preceding claims, wherein the perforated pipe is a corrugated pipe (1).

9. Drain system according to claim 8, wherein the corrugated pipe (1) comprises a valley sections (3) and hill sections(2), wherein the valley sections (3) are provided with openings(4).

10. Drain system according to any of the preceding claims, wherein the perforated pipe (1) is circular.

11. Drain system according to any of the preceding claims, wherein the support structure (7) and the porous sheets (6, 8) consist of the same material, such as polypropylene or PVC.

12. Drain system according to any of the preceding claims, wherein the porous sheets (6, 8) comprise a woven, nonwoven, knitted or braided material.

13. Filter sleeve (5) for a drain system according to any of the preceding claims, said filter sleeve comprising a support structure (7) having an outer surface and an inner surface between which surfaces openings extend, as well as at least one porous sheet (6, 8) supported by said support structure (7).

Drawing