FIELD OF THE INVENTION

The present invention relates to a device for protecting slopes such as, for example, sloping embankments, against erosion, of the kind which is expandable from a fully collapsed state into an expanded cellular body capable of holding in its cells a desired filler material such as native soil, gravel, artificial particulate material, comminuted bark and the like. The invention also relates to a suitable method for protecting slopes.

BACKGROUND OF THE IN ENTION

Known anti-erosion devices of this kind such as, for example, those known by the trademark ENVIROGRID and obtainable from AGH Industries, Inc. are characterized by a plurality of overlapping oblong panels of which every two neighboring ones are interconnected by a plurality of mutually spaced seams such that in the expanded state a honeycomb-like structure is formed with a plurality of prismatic cells with rectangular side walls. For the prevention of erosion a plurality of such devices is placed on a sloping surface such as a sloping embankment and filled with any desired filler material in bulk form which may be poured in from above. Due to their rectangular prismatic shape, the

individual cells are essentially normal to the sloping surface on which the device is placed with the consequence that the filler in each of the cells readily spills over and is dragged down by the eroding action of wind and water. As a result, the erosion preventing effect of the devices diminishes continuously and may after a while even disappear altogether and it may even happen that, when significantly emptied, the devices themselves are blown down the slope by the wind and/or are washed down by rain or irrigation water.

OBJECTS OF THE INVENTION

It is the object of the present invention to provide an improved erosion preventing device of the kind specified free of the disadvantages of the known devices. The second object of the invention is to provide a method for protecting slopes making use of the improved device.

SUMMARY OF THE INVENTION

In accordance with the present invention there is provided for the protection of a sloping surface against erosion, a device expandable from a collapsed into an expanded, cellular body state, and comprising a plurality of oblong panels whicn overlap in the collapsed state and each having top and bottom edges, with every two neighboring panels being connected to each other by a plurality of mutually spaced, parallel connecting zones extending between said top and bottom edges and each forming an acute angle with the bottom edges, whereby when expanded into said cellular body state the device comprises a plurality of prismatic cells with rhomboidal side walls.

When an expanded device according to the invention is placed on a sloping surface, the prismatic cells thereof form an acute angle with the surface so as to be essentially normal or close to normal to the horizontal, whereby the capacity of the device to retain within its cells

bulk filler material and thereby to maintain its erosion-preventing effect is significantly improved over the prior art devices.

According to a particular embodiment of the invention the said acute angle is substantially equal to the difference between the right angle and an average angle of inclination which the sloping embankment surface forms with the horizontal.

The device according to the invention may be made of any suitable material capable of withstanding the eroding effects of the weather, water and the soil, such as, for example, various plastic materials and metals.

The connection zones between the panels may be in any suitable form such as stitched, welded or fused seams, hinges and the like.

The invention further provides a method of protecting a sloped surface against erosion comprising placing on such surface one or more of devices of the kind specified in the expanded, cellular body state so that the prismatic cells thereof are substantially normal or close to normal to the horizontal, and filling the cells thereof with suitable bulk material.

The filling may be provided either by pouring the suitable material into the cells, or by forcing the device down into the sloped embankment.

BRIEF DESCRIPTION OF THE DRAWINGS

For better understanding the invention will now be described, by way of example only, with reference to the annexed non-limiting drawings, in which:

Figs. IA and IB show a prior art device in, respectively, the collapsed and expanded states;

Fig. IC is a schematic illustration of a prior art device of Figs. IA and IB in the operative state;

Figs. 2A and 2B show a device according to the invention in, respectively, the collapsed and expanded states; and

Fig. 2C is a schematic side view of the device of Figs. 2A and 2B in the operative state.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

In Figs. IA, IB and IC there is illustrated a prior art device 10 manufactured by AGH Industries, Inc. The device includes a plurality of parallel oblong panels 12 with every two panels being interconnected by a number of mutually spaced seams 14 which are peφendicular to the top and bottom longitudinal edges of the panel 12. In the collapsed state of the device the panels 12 overlap and form a compact bundle (see Fig. IA). In the expanded state of the device cells 16 formed between the adjacent panels 12 are peφendicular to the bottom surface of the device (see Fig. IB).

When the expanded prior art device 10 is placed on to a sloping surface 20 which is inclined to the horizontal by an angle (see Fig. IC), the walls of the cells 16 are normal to the surface of the slope and thus are deflected from the vertical. It is understood that the steeper the slope the less effective becomes the prior art device in preventing erosion.

In Figs. 2A, 2B and 2C there is illustrated one embodiment of the device according to the invention. The device is in form of a collapsible cellular body 30. Fig. 2A shows the body 30 in its collapsed state in which it forms a compact bundle, and Fig. 2B shows it in the expanded, cellular body state.

Device 30 comprises a plurality of pliable oblong panels 32 welded to one another by a number of mutually spaced parallel seams 34 which form with the bottom edges of the panels 32 an acute angle ^β . Consequently, when the device is expanded, cells 36 formed between adjacent panels shape into oblique prisms with rhomboidal side walls having an acute base angle β. In other words, the side walls of the cells

36 are inclined to the bottom surface of the expanded device 30 by the angle β.

When the device 30 is placed on to a sloping surface 20, e.g. an embankment which is inclined to the horizontal by an angle α as shown in Fig. 2C, the side walls of the cells 36 will be close to normal to the horizontal as distinguished from the prior art device shown in Fig. IC, where the side walls are normal to the sloping surface 20 and inclined towards the horizontal. Moreover, if two angles α and β add to substan¬ tially 90° , the walls of the cells 36 will be vertical, thus providing the optimal protection of the slope from erosion. In practice, if there is calculated an average angle of the slope α _average for a particular sloping surface, a required amount of cellular anti-erosion devices can be tailed for such a slope which will have the desired inclination β of the cells v - ^y u° - aver ge-'*