GB2072734A

GB2072734A - Fascine mattresses and components therefor

Info

Publication number: GB2072734A
Application number: GB8010504A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1980-03-28
Filing date: 1980-03-28
Publication date: 1981-10-07

Abstract

The willow weeps 22 of fascine mattresses are replaced by a tubular plastics structure 10 having at least one layer of a multi-pocket or multi-cell sheet around a sealed and/or filled tubular flexible core. The plastics structure can also be associated with sheet materials to make other forms of protective mattress. <IMAGE>

Description

SPECIFICATION Fascine mattresses and components therefor This invention relates to fascine mattresses and components suitable for making fascine mattresses, which are semi-rigid buoyant structures designed for preventing or reducing the erosion of coasts, sea and river beds and other areas under or alongside bodies of water.

Such mattresses are traditionally constructed from tied bundles or fascines of brushwood, a first layer of such bundles laid in one direction being located upon a second layer of such bundles laid in a direction at right-angles to the first. These two layers of brushwood bundles or fascines form a thick and substantial structure which acts like a filter when the mattress is in place. In order to complete the mattress, the superposed layers of brushwood bundles are consolidated by means of loosely-iaid reeds placed as thinner layers above and below the brushwood and the whole assembly is secured together by long bundles of willow twigs or "weeps", which are laid at spaced intervals along and across the upper and lower faces of the structure, the mutually-crossing willow weeps at the top of the mattress being tied through it to the willow weeps at the bottom.A typicai fascine mattress made in this way may measure 6 mx 9 m and have an overall thickness of 100 cm, for example. The double layer of brushwood bundles is very bulky and, since its basic purpose is to serve as a filter, allowing the controlled passage of water but preventing mass movement of sand, rock or other solid material, attempts have been made to replace the brushwood bundles with a filter fabric layer. Thus, a modern form of mattress is known, in which the willow weeps are attached to either side of a filter fabric.In making fascine mattresses or equivalent structures, the normal practice is to assemble the willow bundles, the reeds and the brushwood bundles or the plastics filter fabric sheets and fastening means as near as convenient to the intended position of use, taking advantage of its buoyancy to float the assembled structure into position, where it is submerged and held by means of weights, e.g. in the form of stones or rocks.

Known fascine mattresses can be expensive, whether of the traditional kind or of the more modern form, because willows of the appropriate quality are produced only in a few locations and therefore large quantities of them and of the other component materials need to be transported when construction and use are planned for a region remote from one where the willows are produced. It is even known for labour and materials to be imported from other countries.

The invention avoids these expenses and other disadvantages and provides both a substitute forwillow weeps and also a substitute for conventional fascine mattressesperse. Moreover, the invention affords unexpected advantages, as it enables subassembly or entire manufacture of mattresses and willow weep substitutes to be carried out independently of regions where the natural products are produced and also enables other applications to be developed.

According to one aspect of this invention, a corrosion and wear resistant structure suitable for use in the assembly of sea and river bed protection mattresses comprises a sealed andlor filled tubular flexible plastics core, at least one layer of sealed multipocket plastics sheet material wrapped around the core and an optional outertubularsheath surrounding the sheet material. This structure can be made to any convenient length and the core can either be filled, e.g. with lightweight plastics filler pieces, or it can be sealed, i.e. in an airtight manner, or both of these expedients can be used to achieve the desired lightness, strength and buoyancy.The multi-pocket or multi-cell plastics sheet gives the core protection from abrasion and also contributes to the lightness and buoyancy of the structure; alternative sheet-like materials having the desired lightness can also be used, if desired. As indicated it can conveniently be the kind of cell-containing laminated product which is often used for the protective wrapping of fragile or expensive articles; also, it can be arranged to as to wrap or surround the core as 2 or more complete layers. The size of the core and the thickness and number of layers of the surrounding sheet material are arranged to suit the size of the outer sheath which is preferably also provided, so that this sheath is a good fit on the light rod-like core and sheet assembly.The outer sheath makes it unnecessary to employ positive fixing of the sheet to the core and has other advantages, as its presence greatly facilitates attachment of the synthetic weep to other components. It can conveniently be made of woven polypropylene cloth, while the plastics sheeting conveniently comprises polyethylene and the tubular core comprises extruded PVC tube. The minimum diameter of the assembled structure preferably is 75 mm.

According to another aspect of this invention, the corrosion and wear resistant tubular structures are assembled with brushwood bundles, with or without reed layers, instead of willow weeps, in making fascine mattresses by the traditional principles of construction.

The invention also consists in other forms of protective mattress constructed from a plurality of preferably spaced and criss-crossed lengths of the tubu larstructure attached to one or two inner or outer plastics or other sheet layers. Further, the invention resides in preventing or reducing the erosive effects of moving water by iocating and retaining any form of protective mattress according to the invention between the water and land subject to erosion. Since the structures according to the first aspect of the invention are desirably made of synthetic materials and since they include among their uses replacement of willow weeps in traditional fascine mattresses, it is convenientto refer to them as "synthetic weeps".

A preferred form of semi-rigid buoyant structure or synthetic weep according to one aspect of the invention is shown in cross-section in Fig. 1 and in perspective view in Fig. 2 of the accompanying draw ing, while Fig. 3 shows a diagrammatic perspective view of a fascine mattress and Fig. 4 shows diagrammatically one form of construction of a protective mattress using such synthetic weeps.

Referring to Figs. 1 and 2, a polyvinyl chloride tube 10 forms a core member for the structure forming the synthetic weep and can be filled if desired with particulate plastics or other inert lightweight material or it can be sealed. At least one layer or, as shown, 2 layers of a polyethylene multi-pocket or multi-cell sheet component 11 is or are wrapped around the core 10, so as to impart the desired light weight and buoyancy to the synthetic weep. An outer tubular sheath 12 of woven polypropylene is located around the sheet component 11 so as to retain the assembly in the form shown. Fastening members can be readily attached to the sheath 12, e.g. lengths of string, and can be used to attach a length of the synthetic weep either to another length orto some other article.

As shown in Fig. 3 in a partly cutaway view, a mattress consists of a large flexible sheet 14, e.g. of plastics or rubber material, having parallel lengths of the synthetic weep shown in Fig. 1 attached to it at spaced intervals. For example, a first series of lengths 15 of the weep are attached to the sheet 14 at spaced parallel locations along the sheet 14 and are criss-crossed by another series of lengths 16 of the weep disposed at spaced parallel locations across the sheet 14 and therefore at right-angles to the first series. Strings or other ties 17 are attached to the sheet 14 where the synthetic weeps 15 and 16 cross one another and are secured around the latter two hold the assembly together.A second flexible sheet 18 can overlie the assembly, so that the synthetic weeps formed by the lengths 15 and 16 are sandwiched between the two sheets 14 and 18 to form a wear and corrosion resistant mattress, which can be used in place of conventional fascine mattresses constructed from willow weeps.

The protective mattress according to the invention shown in Fig. 3 can replace traditional fascine mattresses involving willow weeps for sea and river bed protection works and so enables the proven antiscour method based upon the use of fascine mattresses to be adopted where and when the conventional mattresses are unobtainable. A fascine mattress is shown in Fig. 4, where a lower layer 20 of brushwood bundles or fascines 21, all located in one orientation, is overlaid with another layer 22 of the bundles 21 located in the direction at right-angles to the bundles 21 in the layer 20. Loosely-laid reeds are placed upon the upper layer 22, as indicated at 23, and another layer of reeds (not shown) is placed against the underside of the bundle layer 20.Outside the reed layers 23, weeps 24 are secured in place at spaced intervals both along and across the mattress surface. In a traditional fascine mattress, the weeps 24 are the aforementioned long willow bundles; Fig.

4 also illustrates a mattress according to this invention, having the structure shown and described and where the weeps 24 are synthetic weeps such as illustrated in Figs. 1 and 2.

Any form of the protective mattress of this invention or lengths of the buoyanttubularstructure or synthetic weep can be used to support an oilretention skirt of similar construction to prevent the spread of oil spillages and also assist in collection or locaíised dispersion of them.

The lengths of tubular synthetic weep structure or a one-sided or two-sided "mattress" incorporating them can be formed with a width and length suitable for use as a temporary road or access surface of the "roll out/roll up" kind, e.g. for use over soft ground which would otherwise be impassable.

Claims

1. A corrosion and wear resistance structure suitable for use in the assembly of sea and river bed protection mattresses, which comprises a sealed andlor filled tubular flexible plastics core and at least one layer of sealed multi-pocket or multi-cell plastics sheet material wrapped around the core.

2. A structure according to claim 1, wherein the tubular core is filled with lightweight filler pieces.

3. A structure according to claim 1, wherein the tubular core is both sealed and filled with lightweight filler pieces.

4. A structure according to any preceding claims, wherein the plastics sheet material forms at least two layers around the core.

5. A structure according to any preceding claim, wherein an outertubularsheath surrounds the sheet material.

6. A structure according to claim 5, wherein fastening members are attached to the sheath.

7. A structure according to claim 5 or 6, wherein the sheath comprises woven polypropylene cloth.

8. Astructure according to any preceding claim, wherein the sheet material comprises polyethylene.

9. A structure according to any preceding claim, wherein the core comprises extruded polyvinyl chloride tube.

10. A structure according to any preceding claim, having a minimum diameterof75 mm.

11. A corrosion and wear resistance structure according to claim 1, substantially as described with reference to Figs. 1 and 2 of the accompanying drawings.

12. A fascine mattress, comprising a first layer of aligned brushwood bundles disposed upon a second layer of such bundles laid in a direction at rightangles to the first and mutuaily-crossing synthetic weeps, as herein defined, spaced along and across one face of the mattress and tied through it to similar synthetic weeps spaced along and across the other face of the mattress.

13. Afascine mattress according to claim 12, having reed layers between the bundles and the synthe- tic weeps.

14. A protective mattress, comprising a plurality of spaced and mutually-crossing lengths of a tubular structure as defined in any of claims 1 to 11, attached to at least one side of a sheet material.

15. A protective mattress according to claim 14, wherein inner and outer portions of sheet material are attached to and by the plurality of mutuallycrossing lengths of the tubular structure.

16. A protective mattress according to claim 14 or 15 wherein the or each sheet comprises plastics or rubber material.

17. A protective mattress according to claim 14, 15 or 16, wherein ties attached to the sheet material are secured to the tubular structures where they cross.

18. A method of preventing or reducing the erosive effects of moving water, which comprises locating between the water and land subject to erosion thereby a mattress according to any of claims 12 to 17.

19. Atubular structure according to any of claims 1 to 11 or a mattress according to any of claims 12 to 17, carrying an oil-retention skirt.

20. A method of treating an oil spillage on water, which comprises locating a tubular structure according to claim 19 adjacent the oil on the water so as to prevent the spread of the oil spillage, whereby its collection or dispersal can be assisted.