IES20000284A2 - A soil erosion block - Google Patents

Abstract

There is provided an octagonal-sided soil erosion block (1). The soil erosion block has four straight sides (4) alternately arranged and then has two female sides (6) into which a male side (5) of an adjacent block will interlock. When the blocks are interlocked, there is a natural hole formed between four locks. This gives added porosity and the interlocking gives strength. <Figure 1>

Description

Introduction The present invention relates to soil erosion and in particular to the provision of soil erosion blocks. Such blocks are often referred to as armour blocks and the layers of blocks as armour layers.

Various methods and devices are used to control soil erosion or simply to provide reinforcement for paving areas, embankments and other slopes where soil could erode. There are particular applications in coastal engineering, riverbank protection and breakwater design. A similar problem arises very often with the construction of motorways and roads where there can be erosion of the soil embankments on either side of a motorway. Thus, for safety reasons, there have been many constructions of interlocking blocks, which interlocking blocks act to reinforce the soil.

Increased annual coastal erosion is a problem in many other countries due to general changes in the levels of water in the major oceans and in rivers due to increased urbanisation. For example, many of the locations where coastal erosion is a problem, have beaches backed by sand dunes or soft boulder clay cliffs. The most common method heretofore of protecting the dune or cliff toe from further erosion is to construct a rock revetment at the base. This method of protection is becoming increasing expensive due to the difficulties in sourcing a suitable rock type in sufficient quantities within reasonable transport distance from the site.

There are many constructions of blocks that have been disclosed for this purpose. For example, US Patent Specification No. 5556228 discloses a block for controlling soil erosion, which when blocks are laid together, forms a flat structure. The block has a pair of arms extending from a peripheral side edge and corresponding cavities or recess in the opposite sides. The arms and cavities are located centrally on the block and extend the full depth of the block. Therefore, adjacent units are interlocked but are not interlocked in such a way as to have any lateral stability in the sense that they do not rest on each other. Therefore, they need an additional aid which is provided by wires or cable to prevent dislodging on the impact due to flowing water. -2IE000284 US Patent Specification No. 3,996,715 discloses the block which allows the interlocking between the units. However, the block is hexagonal in shape and is so arranged that each block interlocks with three other blocks. It is generally felt that while the unit of this US Patent Specification No. 3,996,715 would be relatively useful, the problem is that to obtain the natural porosity required for the overall structure, the block is not sufficiently robust in its construction, a void would have to be drilled to obtain porosity.

US Patent Specification No. 1352750 discloses a block somewhat of the same type.

US Patent Specification No. 5020938 discloses a block formed revetment system for controlling soil erosion which discloses a hexagonal block with a tongued and grooved jointing system. The problem is the method of interlocking does not facilitate formation of voids and in general would not be particularly easy to manufacture.

A further problem in relation to the protection of, for example, dune or cliff toes, is the need to ensure that wave energy is dissipated and at the same time, that the material behind the block is not dissipated and washed out through the voids. There is therefore a need for soil erosion block which would overcome the problems inherent in the present construction of such blocks.

Essentially, any such block must have a high structural strength and be able to withstand all loads, be they fabrication, placement, or environmental. Further, it is essential that the block exhibits good hydraulic stability, in other words, it must be able to resist wave forces. Ideally, the geometry of the blocks should be such as to give it a high stability or else, with low stability, it would lead to having to provide blocks of greater general structural strength and size with added cost.

Ideally, as mentioned above, the block should be such that when placed in position, the armour layer should have a high porosity. Indeed, interestingly, it has been found that armour layers with high porosity are more stable and less likely to fail than other armour blocks.

IE000284 -3There are a vast number of armour block designs existing for the protection of breakwaters and coastal structures. Many of these have very complicated shapes which have been found to be difficult to fabricate and often are relatively fragile when placed in position. Generally speaking, all known armour block designs fall into three main types, namely, “bulky”, “slender interlocking” and “hollow block single layer”. These armour block designs are sold under the names TETRAPOD, ACCROPODE, ANTIFER CUBE, SHED, SEEBEE, CORELOC, COB and DOLOS.

The first of these types, namely, those referred to as “bulky” rely on the dead weight to resist the hydraulic forces. Natural rock is obviously the most striking example of such an armour block but unfortunately is often not available in the sizes required for coastal protection or breakwater armoury. Therefore, as mentioned above, artificial concrete units, usually in the form of a cube, are used with weights of up to 90 tonnes. It will be appreciated that these are relatively expensive and difficult to produce, transport and place.

The second type mentioned, namely, “slender interlocking” are units placed in usually one or two layers and rely on mutual interlocking to resist the attack of the waters. These units have a lower weight than the equivalent bulky unit for the same wave conditions. However, breakages are more common due to the slender elements.

Finally, the third type of armour block, namely the “hollow block single layer is now becoming more prevalent. These units usually have a regular shape such that they can be placed on site in a single layer in a predetermined pattern. Generally, they have a very high stability and reasonably large void volumes plus low unit weight. There is often up to 65% or more voids volume so that the unit cost can be reduced. However, they require very high construction tolerances and the loss of structural integrity due to the failure of a few units can lead to failure of the breakwater.

The present invention is directed towards providing an improved construction of such a soil erosion block. Essentially, in any such block, needs to be reasonably bulky to prevent excessive unit breakage. It should interlock to increase stability. It should have some hollows or voids to reduce unit costs and increase porosity and it should be of a regular shape such that it can be placed in a single layer in a regular pattern. -4IE000284 It is also important that it be designed such as to be able to be placed around bends and over what are substantially irregular surfaces. It is also important that any such block should not contain slender elements and those likely to break either in placement or during use. It is also important that they have good hydraulic characteristics with low weight so as to remain cost effective.

The present invention is directed towards providing an improved construction of such soil erosion blocks.

Statements of Invention According to the invention, there is provided an octagonal sided soil erosion block comprising:upper and lower substantially parallel planar faces; four flat straight sides alternately arranged around the periphery of the block between the upper and lower planar faces, each of the four straight sides being in substantially the one vertical plane; a pair of interlocking male sides, each male side having a substantially planar bottom face interconnecting the faces of the adjacent straight sides and a projecting lug extending laterally beyond its bottom face; and a pair of interlocking female sides each having a substantially planar bottom face interconnecting the faces of the adjacent straight sides and a cut-out recess for reception of a projecting lug of a male side.

The advantage of the octagonal shape is that, when arranged together, there will be a natural void between any four blocks.

In one embodiment of the invention, the male and female sides are so configured that their bottom faces contact one another on interlocking. In this way, a relatively stable structure is provided. -5IE000284 In another embodiment of the invention, there is a through hole connecting the upper and lower planar faces of the blocks to provide additional porosity. With this particular construction, ideally the through hole is offset from the centre of the block to provide a regular centre of gravity for the block and further to ensure that places requiring the most quantity of material and robustness are accommodated.

Ideally, the male and female members are alternatively arranged around the block.

In another embodiment of the invention, the sides are arranged around the periphery of the block with one male member separated from the other male member by a straight side.

Detailed Description of the Invention The invention will be more clearly understood from the following description of some embodiments thereof, given by way of example only, with reference to the accompanying drawings, in which:Fig. 1 is a perspective view of a block according to the invention, Fig. 2 is a plan view of the block, Fig. 3 is a side view of the block, Fig. 4 is a sectional view in the direction of the arrows A-A of Fig. 2, and Fig. 5 is a plan view of a typical placement pattern using the blocks.

Referring to the drawings, there is illustrated a soil erosion block indicated generally by the reference numeral 1 having an upper planar face 2 and a lower planar face 3 which are substantially parallel. There are eight sides around the block 1 interconnecting the upper- planar face 2 and the lower planar face 3. Four of these comprise flat straight sides 4 arranged alternately around the periphery of the block 1.

IE000284 -6The four straight sides 4 are in substantially the one vertical plane. A pair of interlocking male sides and interlocking female sides indicated generally by the reference numerals 5 and 6 respectively are provided. The male side 5 comprises a substantially planar bottom face 7 interconnecting the faces of the adjacent straight sides 4 and a projecting lug 8 extending laterally beyond its bottom face 7. Each female side 6 has a bottom face 9 and a cut-out recess 10 for reception of a lug 8. A through hole 15 interconnects the upper planar face 2 and the lower planar face 3. The hole 15 is offset slightly closer to the male sides 6 to ensure that the centre of gravity in a block lies approximately in the geometric centre of the block 15. It also ensures that there is sufficient material between the hole and the adjacent female side 6 and so reduces the breakage potential.

Referring now to Fig. 5, it will be seen how a plurality of blocks 1 are arranged together so that the male sides 5 fit over the female side 6 with their bottom faces 7 and 9 contacting. It will be noted that four blocks 1, when connected together, form a void therebetween, indicated in Fig. 4 by the reference numeral 16. it will be appreciated that the particular construction ensures that different arrangements can be made to the blocks and that the blocks will always intersect and retain each other. For example, using subscript letters to identify the various blocks with the same reference numeral 1, it will be seen that, for example, block 1 (a) fits over block 1 (b) and 1 (c) and thus retains them in position. At the same time, block 1 (d) and 1 (e) fit over block 1 (a) and therefore retain it from moving outwards, thus as well as being interlocked in the XY plane, they are also interlocked in the Z plane or indeed in the plane in certain circumstances.

It is envisaged that the blocks will be manufactured from a suitable high grade concrete without reinforcing. The central hole in the blocks make them particularly suitable for placement.

In the specification the terms “comprise, comprises, comprised and comprising” or any variation thereof and the terms “include, includes, included and including” or any variation thereof are considered to be totally interchangeable and they should all be afforded the widest possible interpretation and vice versa.

IE000284 -7The invention is not limited to the embodiments hereinbefore described, but may be varied in both construction and detail within the claims.

Claims (5)

1. An octagonal sided soil erosion block comprising:upper and lower substantially parallel planar faces; four flat straight sides alternately arranged around the periphery of the block between the upper and lower planar faces, each of the four straight sides being in substantially the one vertical plane; a pair of interlocking male sides, each male side having a substantially planar bottom face interconnecting the faces of the adjacent straight sides and a projecting lug extending laterally beyond its bottom face; and a pair of interlocking female sides each having a substantially planar bottom face interconnecting the faces of the adjacent straight sides and a cut-out recess for reception of a projecting lug of a male side, the male and female sides being alternately arranged.

2. A soil erosion block as claimed in claim 1 in which male and female sides are so configured that their bottom faces contact on interlocking.

3. A soil erosion block as claimed in claim 1 or 2, in which there is a through holes connecting the upper and lower planar faces.

4. A soil erosion block as claimed in claim 2, in which the hole is offset from the centre to provide a regular centre of gravity.

5. A soil erosion block substantially as described herein with reference to and as illustrated in the accompanying drawings.