AU603465B2 - Revetment mattressing - Google Patents

Description

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it COMMONWEALTH OF AUSTRALIA PATENTS ACT 1952.69 COMPLETE SPECIFICATION

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FOR OFFICE USE: Class Application Number: Lodged: Complete Specification Lodged: Accepted: Published: Priority: Int. Class Related Art: T~is diocumn t conltains tile iULcnloents nmade unrdcr Section 19 arld is corr-ect for printing,.r, Name of Applicant:, BRUCK TEXT

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.LES PTY. LIMITED Address of Applicant 10-14 WATERLOO STREET, SUP.RY HILLS N.S.W. 2010.

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Actual Inventor: KLAUS REBENTROST Address for Service: WATERMARK, PATENT TRADE MARK ATTORNEYS SUITE 6, FLOOR 16, TOWN HALL HOUSE, 456 KENT STREET, SYDNEY N.S.W. 2000.

Complete Specification for the Invention entitled, REVEITMENT MATTRESSING The following statement Is a full description of this Invention, irncluding the best method of performing it known to me/us:- 1ii

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A-~tr This invention relates to erosion control and more particularly to a double-layer fabric suitable for filling with fine aggregate concrete so as to "inflate" the said double-layer fabric to for:~ a revetment "mattress" of constant thickness.

In recent years, concrete-filled revetment mattresses have been widely used to stablize and control sites prone to erosion. The revetment mattresses comprise double walled synthetic mattressing with opposed walls woven together, in close juxtaposition, at spaced intervals by "filter points" which remain substantially free from concrete. This results in a mattress of uneven thickness, with concomitant reduction in strength and which, in some applications at least, may well present an unsightly appearance. This latter consideration is not unimportant in these days of environmental curating.

It is therefore an object of the present invention to overcome the above and other disadvantages by the provision of a double-layer fabric able to be filled with fine aggregate concrete in such a way as to "inflate" the said fabric to form a revetment mattress of constant thickness; the two opposed layers of the double-layer fabric being held together by groups of spacer threads disposed at regular, spaced-apart intervals across the fabric so as to allow of a limited separation of the opposed layers on filling to thereby provide a said substantially constant thickness mattress, Preferably, the double-layer fabric is woven from a high-tenacity, multi-filament synthetic fibre, and the spacer threads may be nylon filaments, opposed ends of which are woven into respective opposed fabric layers.

Ideally, each group of the spacer threads is composed of two arrays each of six filaments, these arrays being disposed so as to cross each other, so that a lattice is constituted at the point where the arrays cross.

The fine aggregate concrete filling is 2 j i w~.

advantageously pressure injected between the opposed layer:s after the fabric has been tailored to overlie an area of terrain to be protected from erosion or scouring.

In order that the reader may gain a better understanding of the present invention, hereinafter will be described a preferred embodiment thereof, by way of example only and with reference to the accompanying drawings in which:- S'igure 1 schematically represents a section through the inventive, constant-thickness double-layer fabric, taken along line A-A of Figure 2; Figure 2 illustrates, again schematically, the external appearance of a small portion of the fabric; Figure 3 shows how two arrays of spacer threads cross each other to form a lattice; Figure 4 shows another use to which the inventive revetment mattress may be put; Figure 5 illustrates how the opposed layers may bulge to some extent; while i; 20 Figure 6 shows a typical weave pattern.

Throughout the drawings, like integers are referenced by the same numeral.

Mattressing made from a fabric as hereinafter described and illustrated offers an advanced, fast forming, and economical technique for the construction of revetments both above and below water. Such revetment mattressing is eminently suitable for stabilization, protection, and prevention and repair of the effects of erosion and/or scouring.

The inventive synthetic fibre fabric is woven and 4 put together in such a way that it will provide optimum strength, elongated filtering characteristics and stability.

These filtering characteristics will allow water to filter out but will retain solids, and will also reduce the water/cemelnt ratio, during pumping under pressure, from 0.65 to approximately 0.35.

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K The fabric is preferably woven from high-tenacity, multi-filament nylon or other suitable synthetic fibre such as polyesters, polypropylene, etc. and is immune from attack by acids, alkalis, organic solvents and biological organisms.

The two opposed fabric layers of the double-layer fabric are held together by groups of spacer threads which are disposed at regular, spaced-apart intervals across the Sfabric so as to allow of a limited separation of the opposed 1i 10 layers on filling with concrete, to thus provide a concrete layer and so a revetment mattress of substantially constant or regular thickness.

The inventive double-layer fabric is woven on a weaving machine provided with "dobby motion" but without the requirement for a second beam or a special creel to accommodate the spacer threads as these threads constitute an intrinsic part of the top and bottom fabric layers see the weave pattern shown in Figure 6.

A variation in the weave, as the extension of the spacer threads B and C over more weft threads X 1 will permit production of fabrics which will "inflate" to various thicknesses, for example 50mm; 75mm; 100mm; 125mm; and from 150mm. up to 400mm. A variation in the number of spacer threads B and C, and the variation of the ground threads between the groups of spacer threads will alter the final surface appearance of the revetment mattress.

The mattressing fabric is cut to shape and laid out over an area of terrain and the cut edges secured together, perhaps by stitching, to form the mattress; at least one filling opening is left unstitched. Minimal site preparation is required.

Pressure injection of fine aggregate concrete inflates the double-layer fabric to form a revetment mattress of constant thickness, having substantially parallel sides. Pressure injection, as has been previously stated, reduces the water/cement ratio from 0.65 to about 4 iI 0.35 and the so-produced mattress has the ability to attenuate and/or halt the erosive forces generated by bnth man and nature.

Referring now to the drawings, Figure I represents a section through the inventive, constant thickness double-layer fabric, taken on line A-A of Figure 2, which latter Figure schematically shows the external appearance of the fabric. The two opposed layers, respectively referenced 1;2 are preferably woven from multi-filament nylon thread, on a loom which is provided with the aforesaid "dobby motion" insert elements, enabling the various spacings to be made.

Layers 1 and 2 are held together by groups of spacer threads 3 which are disposed at regular, spaced-apart intervals across the fabric so as to allow of a limited separation of the opposed layers, thus these staggered groups of spacer threads 3 between them define a plurality of interstitial spaces, referenced 4, for reception of the pressure-injected fine aggregate concrete.

20 As will be seen best in Figure 3, each group 3 is composed of a number of nylon filaments, opposed ends of which are woven into their respective opposed fabric layers.

In the embodiment shown, there are twelve such nylon filaments two arrays of six each, these arrays being so disposed as to cross one another; where they cross, the twelve nylon filament spacer threads constitute a lattice endowing the two layers with great flexibility with respect to each other.

As shown in Figure 5, while those portions of fabric between groups of spacer threads 3 will bulge slightly when inflated with fine aggregate concrete, the resulting revetment mattress has substantially parallel sides or surfaces.

Referring back now to Figure 4, this shows an exemplary use for the inventive mattress. A railway line 6 is shown running along an embankment, generally referenced 1 7, through which a drainage conduit or pipe 8 is driven.

Over the steeply-inclined revetment, below the railbed ballast 9, is laid an inventive revetment mattress tailored to fit around the embouchure of pipe 8. When the fine aggregate concrete in-fill has cured, the embankment is effectively stabilized.

Many other uses for the revetment mattressing according to the present invention can be postulated. For example, a foreshore can be protected; the slope is prepared by loosely raking it; an anchor trench is dug at the top of the slope; and a toe trench dug at tne bottom. The site is measured and the mattressing tailored to fit on site. The anchor trench is filled with concrete and the mattress pressure-inflated, and the anchor trench then finally backfilled.

There again, sea anchors and buoy moorings may be constructed using the inventive mattressing. A steel mesh cage may have located therein a plurality of mattress elements which are then pressure-injected. These mattresses assume the shape of the pre-contoured cages to provide solid, virtually immovable foundations for in-situ sea anchors and buoy moorings. In similar fashion underwater jj pipe-lines may be encased in the inventive mattresses.

Again in similar fashion, moulded blocks may be made, particularly as beach front groins for foreshore protection.

In all applications, the fine aggregate concrete in-filling may be coloured as with brown oxide so as to blend in with the environment.

From the abovegoing, it will be readily appreciated by those skilled in the art that numerous variations and modifications may be made to the invention without departing from the spirit and scope thereof as set out in the accompanying Claims.

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Claims (4)

1. A double-layer fabric able to be filled with fine aggregate concrete in such a way as to inflate the said fabric to form a revetment mattress of substantially constant thickness; two opposed layers of said double-layer fabric being held together by groups of spacer threads, each spacer thread being constituted by a flexible filament, opposed ends of which are woven into respective opposed fabric layers; said groups of spacer threads being disposed at regular, spaced-apart intervals across the fabric so as to allow of a limited separation of said opposed layers on filling, to thereby provide a said substantially constant hickness revetment mattrass: characterised ia that each said group of spacer threads is composed of two arrays, each of a plurality of flexible filaments, the said arrays being disposed so as to cross each other, whereby a lattice is constituted at the point where the arrays cross.

2. The double-layer fabric as clrzimed in Claim 1, wherein said fabric is woven from a high-tenacity, multi-filament synthetic fibre.

3. The double-layer fabric as claimed in claim 1 or claim 2, wherein said fine aggregate concrete filling is .pressure-injected between said opposed layers after said fabric has been tailored to overlie an area of terrain to be protected from erosion or scouring.

4. A double-layer fabric able to be filled-with fine aggregate concrete in such a way as to inflate the said fabric *to form a revetment mattress of substantially constant thickness, substantially as hereinbefore described with reference to the accompanying drawings. A constant thickness revetment mattress made f rom the double-lAyer fabric as claimed in any one of the preceding claims. DATED this 24th day of July 1990. BRLJC TMVUILES PTY. LIMITED by WATEmAM TRADE MARPK ATIOFRNEyS. 0~1