WO1997004178A1

WO1997004178A1 - Earth drains

Info

Publication number: WO1997004178A1
Application number: PCT/CA1996/000447
Authority: WO
Inventors: Joseph Clement Brodeur; Vicko M. Von Stedingk; Mark E. Siemonsen
Original assignee: Joseph Clement Brodeur; Von Stedingk Vicko M; Siemonsen Mark E
Priority date: 1995-07-19
Filing date: 1996-07-04
Publication date: 1997-02-06
Also published as: TW356491B; AU6185296A; CA2154239A1

Abstract

The invention is an earth drain, comprised of a core consisting of an elongated, flexible web (3) having an array of discrete, longitudinally and transversely spaced projections (4) on at least one surface thereof, and a filter (2) of sheet-like water permeable material encasing the core and adapted to be maintained in spaced relationship to the web (3) by the free ends of the projections (4). The projections (4) are arranged with regular spacing in parallel rows disposed transversely of the web, and projections (4) in alternating transverse rows are disposed between the projections (4) in an adjacent row. A transverse line touching the outermost periphery of at least some of the projections (4) in each row intersects part of some of the projections of an adjacent row causing an overlap (B) between at least some of the projections (4) in adjacent rows in the longitudinal direction of the web (3).

Description

EARTH DRAINS

The present invention relates to earth drains, and, more particularly, to the type of earth drain having a core comprising a relatively flat, flexible, elongated web encased in a water permeable filter material which is maintained in spaced relationship to at least one side of the web by a plurality of projections or studs extending from the surface of the core. A drain of this type is disclosed in the Wager Canadian Patent No. 1,015,173 issued August 9, 1977. Drains of the type disclosed in the aforementioned Canadian Patent No. 1,015,173 function very effectively provided that they are not subjected to extreme microfolding, which might occur as a result of the subterranean shifting of the soil, for example, during a soil consolidation process. Such extreme microfolding might result in the drain being very sharply folded back upon itself which, in the case of the conventional drain, might result in the filter material being urged into contact with the drain core web, resulting in a partial or complete blockage of the drain at the points of contact. In such circumstances, the drain ceases to function effectively to permit a free flow of water along the entire longitudinal extent of the drain. While this problem is not normally associated with studded drains, it might occur where the longitudinal row to row spacing of studs ls sufficient to allow the filter material to contact the web when the drain is sharply folded over upon itself; where studs or projections are on only one side of the web; the stud height is Insufficient to keep the filter material spaced from the core web at all times; or the stud height on the inside of the bend is not sufficient to prevent sharp bends. In accordance with the present invention, this deficiency in known drains can be eliminated through an appropriate arrangement of projections on the drain core web. Accordingly, the Invention broadly resides in an earth drain of the type comprising a core consisting of an elongated flexile web having an array of discrete, longitudinally and transversely spaced projections on at lease one surface thereof, and a filter of sheet-like water permeable material encasing the core and adapted to be maintained in spaced relationship to the web by the free ends of such projections. The projections are arranged in parallel rows disposed transversely of the elongated web with projections ln alternating transverse rows being disposed between the projections in an adjacent row. The transverse rows of projections are so spaced in the longitudinal direction of the web that a transverse line touching the outer periphery of the base of at least some part of at least one projection in a row, will intersect at least some of the projections in an adjacent row. In other words, at least some of the projections in one transverse row overlap, in the longitudinal direction of the web, at least some of the projections in an adjacent row, and this arrangement will prevent the web from being bent to such an extent that the filter is urged against the web.

In drawings which illustrate embodiments of the invention: Figure 1 - a schematic plan view, partly broken away, of an end segment of a known drain; Figure 2 - a cross-section of the drain depicted in Figure

Figure 3 - a schematic side elevation of a distorted drain subjected to microfolding at C; Figure 4 - a magnified view of a microfolded section of known drain; Figure 5 - a schematic plan view, partially broken away, of an end segment of drain ln accordance with the invention; Figure 6 - a pictorial representation of an alternative arrangement of projections; Figure 7 - a magnified view of drain in accordance with the invention subjected to microfolding; Referring to Figures 1 and 2, lt can be seen that the conventional drain, 10, consists of a flat, flexible elongated core in the form of a web, 3, having a plurality of projections, 4, extending from at least one surface thereof. The projections, 4, are arranged in transverse rows across the width of the web, and are regularly spaced within such rows. Adjacent rows are similarly spaced in the longitudinal direction of the web, such that a transverse line touching the outermost point on the periphery of the projections in a row will be spaced a distance A from a corresponding line touching the projections in an adjacent row. The projections in each alternating row are spaced, in the transverse direction, between the projections of an adjacent row so that projections in alternating rows are offset in the transverse direction of the web with respect to the projections in adjacent rows as depicted ln Figure 1.

While projections may extend from only one side surface of the web, typically, projections will extend from both surfaces, as depicted in Figure 2, as this effectively doubles the capacity of the drain. The projections are of a frusto-conical configuration in the illustrated embodiment, although they could be of cylindrical or other shape. For ease of illustration, alternating rows of projections depicted in Figure 2 are solid and stippled.

Where projections extend from both side surfaces of the web, it is useful to include apertures, 6, at selected locations throughout the web to permit the passage of water from one surface of the web to the other if, for any reason, the drain passage on one surface of the web becomes blocked. For example, under localized soil pressures, the filter might be pressed against the web, 3, effectively blocking the flow of water along the drain at the particular location. Where these apertures are provided, the water on the blocked side of the drain may pass through the apertures and flow along the unblocked side of the drain.

Figure 3 depicts a drain, 10, which has been subjected to microfolding as a result of the subterranean shifting of the soil through which the drain passes. At the location marked C, the drain is reversed sharply upon itself, resulting in a bending of the drain such as that depicted in Figure 4. For illustrative purposes, and simplicity, Figure 4 depicts a drain of the type depicted in Figures 1 and 2, but having projections, 4, on only one surface of the core web, 3, and projections in adjacent transverse rows are shown as solid and stippled. As will appear from this figure, when subjected to a sharp bend during severe microfolding, the longitudinal spacing of the transverse rows of projections is such that the encasing sheet-like filter, 2, is brought into contact with the adjacent surface of the web, 3, which effectively blocks the flow of water through the drain. While Figure 4 illustrates an embodiment in which the projections appear on only one surface, the same blocking action could occur in a drain having projections on both side surfaces of the web. If the projections are spaced sufficiently far apart, it will be possible for the filter to be forced into contact with both side surfaces of the web, and thereby effectively block the flow of water through the drain.

Figure 5 illustrates an arrangement of projections in accordance with the subject invention, and the same reference numerals have been used for corresponding drain elements. The principal difference between the arrangement of projections in accordance with the invention and the arrangement of projections ln the known drains, lies in the longitudinal spacing of adjacent transverse rows of projections. In accordance with the invention, the transverse rows of projections are spaced such that a transverse line touching the periphery of some of the projections in one transverse row will intersect at least some of the projections of an adjacent transverse row, or vice versa. In other words, rather than a longitudinal gap, A, between the projections of adjacent rows, there will be an overlap, B, as illustrated in Figure 5. Accordingly, when such a drain is subjected to microfolding as depicted in Figure 3, it will not be possible for the filter material to be urged against the adjacent surface of the web, 3, because the overlap between adjacent transverse rows of projections will prevent the kind of bending depicted in Figure 4, and will result in a bend such as that depicted in Figure 7. Even if the filter material is forced inwardly toward the adjacent web surface, the overlap between the adjacent rows of projections would prevent the filter material from being forced sufficiently far that it could actually touch the web surface. Accordingly, by providing overlap between adjacent transverse rows of projections, blockage due to extreme microfolding is effectively eliminated.

While the projections depicted in Figure 5 are of regular circular cross-section, it is not necessary that all of the projections be identical, nor ls it necessary that the overlapping relationship exist between every projection in every row. Reference may be had to Figure 6 which illustrates projections,4, of a similar configuration to those depicted in Figure 5, together with projections, 4', which are of oval configuration in alternating rows, which projections, 4', are themselves interspersed with regular circular projections, 4. As can be seen from Figure 6, overlap exists between the projections, 4', of one transverse row of projections and the projections, 4, in an adjacent transverse row of projections, and this will produce a result similar to that depicted in Figure 7 when the drain is subjected to microfolding. The advantageous results of the invention can therefore be achieved regardless of the cross-sectional shape of the projections, provided that the overlapping relationship between transverse rows exists. The overlap may exist in any plane, either through the free ends of the projections or, where the projections are not cylindrical, in a plane intermediate of the web and the free ends. However, overlap at the free ends is preferred.

While the free surface area of a drain in accordance with the present Invention might be somewhat less than that of a conventional drain, the inventive drains exhibit sufficient free surface area to adeguately receive water discharged from the soil. The free surface area is the area of the fabric which is in contact with the soil through which water can flow freely. The support points, where the fabric rests against the free end of a projection, cannot receive water. Accordingly, the free surface area is calculated by subtracting the contact area of the fabric support points (the free ends of the projections) from the total area of the filter fabric in contact with the soil.

Claims

CLAIMS :

An earth drain of the type comprising a core consisting of an elongated flexible web having an array of discrete, longitudinally and transversely spaced projections on at least one surface thereof, and a filter of sheet-like water permeable material encasing said core and adapted to be maintained in spaced relationship to at least one surface of the web by the free ends of said projections, characterized in that said projections are arranged in longitudinally spaced parallel rows disposed transversely of said web, with projections in alternating transverse rows being disposed between the projections in adjacent rows, and a transverse line touching the outer periphery of at lease some of the projections in each row intersecting at least some of the projections of an adjacent row.

An earth drain as defined in claim 1, wherein said web has parallel side edges, said transverse rows of projections are disposed perpendicular to the longitudinal axis of said web, and projections in alternating rows are disposed midway between the projections of an adjacent row.

An earth drain as defined in claim 1 or 2, in which said projections are of circular cross-section and have flat free end surfaces which are parallel to the plane of the web.

An earth drain as defined in claim 3, wherein said projections are frusto-conical ln configuration, diminishing in cross-section from the web to the free end thereof.

5. An earth drain as defined in claim 3, wherein said projections are of cylindrical configuration.

6. An earth drain as defined in claim 1, 2, 4, or 5, wherein said transverse line touches the periphery of the projection at the free end thereof.

7. An earth drain as defined in claim 4, wherein said transverse line touches the periphery intermediate of the surface of the web and the free end of the projection.