GB2258486A

GB2258486A - A panel for a subsurface barrier screen

Info

Publication number: GB2258486A
Application number: GB9113908A
Authority: GB
Inventors: Robert David Essler
Original assignee: Keller Ltd
Current assignee: Keller Ltd
Priority date: 1991-06-27
Filing date: 1991-06-27
Publication date: 1993-02-10
Also published as: GB9113908D0

Abstract

An end portion of a flexible polymeric panel 1, installed in a trench 3, has concertina folds 2, near one end. The panel lies with its upper edge 4 just below ground level 5. The last fold terminates in a fixing margin 6. Upon unfolding as shown in Fig. 3 the fixing margin 6 is presented horizontally at ground level. The next panel 1 a can then be joined sealingly to the horizontally presented margin 6, e.g. by mechanical fixing, gluing, fusion welding of different types, or proprietary joint assemblies, more controllably than when attempting to seal a vertical seam on the same material standing as the end of a panel in narrow trench 3. Once the two panels are joined the second panel 1 a is lowered into the trench 3 and pulled away from the original panel so as to open out the folds 2. <IMAGE>

Description

BARRIER SCREEN This invention relates to thin panels of synthetic polymeric materials adapted for assembly side by side to form a subsurface screen, and to the assembled screen, and its mode of assembly.

It is known to provide a soil-arresting and soil-separating screen by erecting, usually in a trench, a number of thin polymer panels side by side.

Typically, this is done by vertical interlocking of the edges of the panels by some sort of male/female joint until a screen of desired length is formed.

As well as being effective in its function of soil-arresting, the screen should be as far as possible watertight and air tight, for control of subsurface water of noxious and/or inflammable gas, e.g. leachate water or methane formed in landfill dumps, or for control of underground water flow near industrial sites, weirs and like river works etc. Typically some expedient is adapted in an attempt to seal the joint in the trench. However, it is not always easy to seal this vertical joint.

The present invention in one aspect provides a panel modified to facilitate watertight and gas tight seal to a neighbouring panel while being installed to form a vertical screen in a trench.

One aspect of the invention consists in a rectangular panel of synthetic polymeric material capable of sealing attachment at opposed edges to like panels so as to constitute an elongate barrier screen: in which a plurality of folds in the material, parallel to the joining edges and located at least at or near one such edge provide a pleated configuration extending to one or both sides of the plane of the panel, the total length of the folded area when extended being generally equal to one quarter of the circumference of a notional circle with radius equal to the length of the joining edge of the panel.

The folds are preferably generally equispaced, to give a concertina-like configuration of pleats, and are usually located at one end only of the panel, immediately continuous with a joining margin to the next panel. They can be of the same or different, e.g.

lesser, material thickness than that of any unfolded part of the panel, and usually extend to either side of the plane of the panel.

The invention further extends to a method of assembly of a subsurface screen from panels as defined above, in which (i) such a panel is located in a trench with the folds vertical, (ii) the folds in the panel are unfolded at the lower edge without unfolding at the upper edge, so that an opened fan configuration of pleats is formed to present the edge of the panel at or above ground level (iii) a subsequent such panel is sealingly joined to the thus-presented edge of the first panel (iv) the subsequent panel is placed vertically in the trench while extending the unfolded regions of the pleats of the first panel and (v) the operations (ii) (iii) and (iv) are repeated until the desired length of screen is built up.

The invention further extends to the subsurface screen as erected by the method as described above, and to a method of controlling subsurface soil, water and/or gas movement in terrain such as landfill, in which a trench is dug and the above method of installing a subsurface barrier screen is carried out.

The invention will be further described with reference to the accompanying drawings, in which: Figure 1 shows part of a first embodiment of panel in diagrammatic plan view, Figure 2 is a side view of the panel shown in Figure 1, Figure 3 is a sideview of the panel shown in Figure 2 ready for sealing attachment to a subsequent such panel, Figure 4 is a top view of Figure 3, Figure 5 is a top view of part of the panel extended and as incorporated into a vertical subsurface screen, and Figure 6 is a side view of Figure 4.

In the drawings an end portion of a flexible polymeric panel 1, already installed in a trench 3, is provided with a succession of large pleats or concertina folds 2, integral with or sealingly attached to the material of the panel. The folds 2 can be of thinner material than the panel 1 or can be of the same thickness The lateral extent L of the folds 2 is such that the panel can readily be inserted into the conventional installation trench 3 to lie with its upper edge 4 just below ground level 5. The last fold terminates in a fixing margin 6.

The number of folds is such that the total length of folded material, when opened out, would generally correspond in length to one quarter of the circumference of a circle with radius equivalent to the height of the panel 1. Thus, if the bottom corner of the folded material is pulled up along the path A (Fig.3) a configuration such as shown in Fig.3 is achieved. In this configuration the fixing margin 6 is presented horizontally at ground level, the thickness of the material itself causing a small upward displacement of this margin, at 7, so as to clear the ground level edge 5 of the trench 3.

The next panel la can then be joined sealingly to the horizontally presented margin 6, this being shown as a vertical addition in Figure 3 and a horizontal addition in Fig.4. In each case panel la itself possesses, at its further edge, not shown, a folded configuration identical with configuration 2.

The actual mode of joining can vary depending upon the polymer materials used and their sizes. Mechanical fixing, gluing, fusion welding of different types, or proprietary joint assemblies can all be used. They are all much more controllable when producing a horizontal join on a gripped material than when attempting to seal a vertical seam on the same material standing as the end of a panel in a narrow trench 3.

Once the two panels are joined the second panel la is lowered into the trench 3 and pulled away from the original panel so as to open out the folds 2. Figure 5 shows the outcome from above, and Figure 6 in side view.

While the exact dimensions of the panel, the number of panels used, the thickness of panel and the folded material and the depth of folding and number of folds can vary, and do not limit the broad scope of this invention, a typical panel will possess the following characteristics: Height 5-lOm Length 10-20m Thickness of panel 1-3mm Thickness of fold material 0.5-2mm Number of folds 8-20 Lateral extent of folds. 500-900mm Modifications may be made to the above embodiment.

Thus, it is possible, though less preferred, to place the folds somewhat within the expanse of panel i.e. to leave a flat panel space next to the edge and not just a fixing margin. The presented edge for attachment would then project to a greater extent above the ground, or possibly project at an angle to the horizontal, either of which could be acceptable in certain circumstances.

Moreover it is possible, although not usually desirable to present folds elsewhere in the screen merely for expansion purposes. Indeed the screen may be completely folded.

Claims

CLAIMS:

1. A rectangular panel of synthetic polymeric material capable of sealing attachment at opposed edges to like panels so as to constitute an elongate barrier screen: in which a plurality of folds in the material, parallel to the joining edges and located at least at or near one such edge provide a pleated configuration extending to one or both sides of the plane of the panel, the total length of the folded area when extended being generally equal to one quarter of the circumference of a notional circle with radius equal to the length of the joining edge of the panel.

2. A rectangular panel as claimed in claim 1 in which the folds are generally equispaced, to give a concertina-like configuration of pleats.

3. A rectangular panel as claimed in claim 1 or 2 ifl which the folds are located at one end only of thr panel, immediately continuous with a joining margin to the next panel.

4. A rectangular panel as claimed in claims 1, 2 or 3 in which the folds are of lesser material thickness than that of any unfolded part of the panel.

5. A rectangular panel as claimed in any one preceding claim in which the folds extend to either side of the plane of the panel.

6. A rectangular panel as claimed in any one preceding claim the characteristics of which are: Height 5-lOm Length 10-2Om Thickness of panel 1-3mm Thickness of fold material 0. 5-2mm Number of folds 8-20 Lateral extent of folds. 500-9OOmm

7. A method of assembly of a subsurface screen from panels as claimed in any one preceding claim, in which (i) such a panel is located in a trench with the folds vertical, (ii) the folds in the panel are unfolded at the lower edge without unfolding at the upper edge, so that an opened fan configuration of pleats is formed to present the edge of the panel at or above ground level (iii) a subsequent such panel is sealingly joined to the thus-presented edge of the first panel (iv) the subsequent panel is placed vertically in the trench while extending the unfolded regions of the pleats of the first panel and (v) the operations (ii) (iii) and (iv) are repeated until the desired length of screen is built up.

8. The subsurface screen as erected by the method as claimed in claim 7.

9. A method of controlling subsurface soil, water and/or gas movement in terrain such as landfill, in which a trench is dug and the method of installing a subsurface barrier screen as claimed in claim 8 is carried out.