GB2211533A

GB2211533A - A block and a surfacing formed from a plurality thereof

Info

Publication number: GB2211533A
Application number: GB8817479A
Authority: GB
Inventors: Clive Anthony Cridge
Original assignee: BROOKLYNS Ltd
Current assignee: BROOKLYNS Ltd
Priority date: 1987-07-24
Filing date: 1988-07-22
Publication date: 1989-07-05
Anticipated expiration: 2008-07-22
Also published as: GB8717569D0; GB8817479D0; GB2211533B

Abstract

A block is shaped to interfit with corresponding blocks to form a surfacing on a surface, in particular to form a revetment for protecting for example a riverbank. One side surface of the block has V-shaped projections (30, 32) and the opposite side surface has V-shaped recesses (34, 36). The V-shaped projections on one block locate within the V-shaped recesses of an adjacent block to resist relative displacement of the blocks in the plane of the surfacing. The weight of the block is such that its weight per unit area of surface covered is about 400kg/m<2> or more. <IMAGE>

Description

A BLOCK AND A SURFACING FORND FROM A PLURALITY THEREOF This invention relates to a block shaped to interfit with other blocks to form a surfacing and is particularly, though not exclusively, concerned with blocks which may be used to form a revetment for protecting a surface exposed to moderate to severe erosive forces such as a bank of a fast flowing river.

The use of interfitting blocks, formed usually from pre-cast concrete, to protect surfaces subject to erosion is well known. Various shapes of blocks have been proposed which are usually laid by hand, to form a structure which resists erosive forces.

There is a need however, for a block which may be used with other such blocks to form a revetment to protect areas subject to moderate or severe erosive forces such as the banks of a fast-flowing river, tidal estuaries, and marinas. There may be problems in forming the revetment under the erosive conditions. In circumstances where the erosive conditions are not continuously in existence, for example, On a sea wall, it may be important that the revetment is formed quickly.

According to one aspect of the invention there is provided a block shaped to interfit with corresponding blocks to form a surfacing on a surface and having contoured side surfaces to cooperate with contoured side surfaces of said corresponding blocks to resist relative displacement of the blocks in the plane of the surfacing, wherein the block is such that its weight per unit area of said surface covered is about 400 kg/m2 or more.

The block is preferably made from concrete.

Preferably, the block is adapted to be secured to at least one further block, in use. The block is preferably provided with a passage which, in use, receives an elongate element thereby to secure the block to at least one further block. The passage may extend transversely to a contoured side surface.

Preferably, the passage extends substantially at right angles to the side surface whereby an elongate element extending through aligned passages formed by several adjacent blocks may anchor the blocks together to form a stable surfacing. In particular, such a surfacing is resistant to displacement of individual blocks out of the plane of the. surfacing.

The block may be provided with two sue dosages.

Preferably, the passages are parallel to each other.

The elongate element may be rigid but preferably is flexible and comprises cable or rope or the like.

The contoured side surf aces may comprise a V-shaped projection arranged to locate within a corresponding V-shaped recess in an adjacent block in the surfacing. The V-shaped projection may extend over the height of the block. Preferably, the block is provided with two such V-shaped projections on a side surface and two such V-shaped recesses on an opposite side surface thereof. However, where the blocks are laid in a stretcher bond (half-bond) manner blocks having one V-shaped projection and one recess may be provided to "fill in" the end of a bond.

In the case where a passage is provided the passage preferably extends through the block to emerge at the apex of a V-shaped projection and a V-shaped recess of the block.

An end surface of the block may be provided with a projection which is arranged to locate within a correspondingly shaped recess in another block.

An upper surface of the block may be formed with an irregular surface for example to simulate natural stone. In the case of a concrete block natural stone may be set into the concrete whilst it is formed, so that in the finished block the stone stands proud of the concrete.

A revetment formed from blocks having such irregular surfaces is advantageous in that it will disrupt water flowing over its surface. Thus, where the revetment is used to protect a river bank the irregular surface of the revetment will impede the flow of the river and reduce its erosive potential.

Alternatively, where the revetment is used in coastal defence works it will hamper wave run up over the revetment Additionally, the natural stone may be more aesthetically acceptable and the kind of stone may be chosen to match local stone types.

An edge of the block may comprise a surface transverse to the upper and side surfaces of the block. Thus, the block is provided with a chamfered edge. A chamfered edge is desirable in that it reduces the possibility of damage, such as chipping, occurring to the edge especially during assembly of blocks into a revetment. Preferably the edge surface comprises further distinct flat portions transverse to the upper and side surfaces.

According to another aspect of the invention there is provided a surfacing comprising a plurality of interfitted blocks as described in any of the nine immediately preceding paragraphs.

In the case where a passage is provided in each block for an elongate element, means is preferably provided to tension the element to hold the surfacing together.

Blocks and surfacings in accordance with the invention will now be described, by way of example and with reference to the accompanying Figs in which; Fig. 1 is a plan view of a block in accordance with the invention; Fig. 2 is a side view of the block shown in Fig. 1; Fig. 3 is an end view of the block shown in Fig. 1 and Fig. 2; Fig. 4 is a perspective view of the block shown in Figs. 1, 2, and 3; Fig. 5 is a plan view of a block which may be interfitted in half bond manner with blocks of the type shown in Figs 1-4 to form a revetment; Fig. 6 is a side view of the block shown in Fig. 5: Fig. 7 is a plan view of part of a revetment formed by interfitting blocks of the types shown in Figs.

1-4 and 5 and 6; Fig. 8 is a plan view of another block in accordance with the invention; Fig. 9 is a side view of the block shown in Fig. 8; Fig. 10 is an end view of the block shown in Figs. 8 and 9; Fig. 11 is a perspective view of the block shown in Figs. 8, 9 and 10; Fig. 12 is a plan view of a block which may be interfitted, in half bond manner, with blocks of the typo shown in Figs. 8, 9, 10 to form a rcvotmcnt; Fig. 13 is a side view of the block shown in Fig. 12; Fig. 14 is a plan view of a portion of a revetment formed by interfitting blocks of the types shown in Figs. 8-11 and Figs. 72 and 13.

The block 10 shown in Figs. 1, 2, 3, and 4 is cast in concrete and comprises upper surface 12, lower surface 14, opposed contoured side surfaces 16, 18 and end surfaces 20 and 22 substantially at right angles thereto. Lumps of natural stone 24, 25, 26 and 27 are set into the upper surface of the block during casting of the block.

The contoured side surfaces 16, 18 of the block 10 are formed into V-shaped recesses 34, 36 respectively.

Tubular passages 38 and 40 are defined by the block and extend substantially parallel with ends 20 and 22. In use, each passage receives an elongate element such as a steel or synthetic cable. In the constructed revetment the cables, passing through aligned passages in adjacent blocks, anchor the revetment structure together, The block 50, as shown in Figs. 5 and 6, is one half the length of block 10 and has one V-shaped projection 52, one V-shaped recess 54, and one passage 56 for receiving, in use, a cable. The block 50 also comprises upper surface 58, lower surface 60, opposed contoured side surfaces 62, 64 and ends 66 and 68 substantially at right angles thereto.

In use, blocks 50 are used to "fill in" the ends of rows of blocks 10, interfitted in stretcher bonds (half bond), forming a revetment 60 as shown in Fig.

7. Blocks 50a and lOa, having a straight side surfaces SOb and lOb respectively, are used to provide the revetment with a straight upper edge 60a.

The straight upper edge 60a may be desirable for aesthetic reasons. However, the lower edges of the revetment will often in practice be bellow water level and may be left unfinished.

Cables 70, 72, 74 and 76 are passed through aligned apetures 38, 40 and 56 in said blocks to hold the revetment together. The apertures are aligned as shown in Fig. 7. Each cable 70-76, is formed into a loop, e.g. 70a, at each end thereof. The loop is secured by a collar, e.g. 70b, which is hydraulically swaged about the cable 70 during formation of the loop 70a. The cable is formed from stainless steel.

However, other materials are contemplated for the cable e.g. high tenacity parallel filament terylene encased within a resistant sheath.

The revetment 60 may be laid in situ and cables passed through the passages to hold the revetment structure together. Alternatively, thc revetment may be formed from panels of such blocks produced in a factory and delivered to the site already interconnected by cables. Such panels may be up to 12 metres in length, although an average of 6-8 metres is preferred, and may be around 3 metres in width. Such an average panel would be held together by 14 cables. The pre-production of assembled panels is desirable in that it allows a revetment to be assembled quickly at a site, for example during a particularly low tide. The revetment thus formed has an average weight of 400kg per square metre. In practice, the weight of the surface of the revetment may vary from 390 to 415 kg per m2.

The use of cables to hold the block and the revetment together, is particularly advantageous in that the revetment thus formed as a degree of flexibility which facilitates mechanical handling and placing of the revetment in use. In particular, the revetment thus formed is able to flex slightly in response to surface movement e.g. soil subsidencc.

Another block 100 in accordance with thc invention is shown in Figs. 8, 9, 10, and 11 and comprises a smooth upper surface 102, lower surface 104, contoured side surfaces 106, 10S, and ends 110 and 112 substantially at right angles thereto. Block 100 further comprises V-shaped projections 114, 118 and opposed V-shaped recesses 120 and 122. Tubular passages, which in use receive a cable as previously described for blocks 10 and 50, are formed substantially parallel to the ends 110 and 112.

The block 100 has a chamfered upper edge 140, which comprises portions 142, 144 and 146 transverse to the upper surface 102 of the block.

The chamfered edge section is advantageous in that it facilitates handling of the block and minimises chipping of the edge during assembly of. the revetment.

The block 150 as shown in Figs. 11 and 12 is one half the length of block 100 and has one V-shaped projection 150, one V-shaped recess 154, and a passage 156 for receiving, in use, a cable. The block 150 also comprises smooth upper surface 158, lower surface 160, opposed contoured side surfaces 162, 164 and ends 166 and 168 substantially at right angles thereto.

In use, blocks 150 are used to "fill in" the ends of rows of blocks 100 interfitted in stretcher bond to form a revetment 200 as shown in Fig. 13 and which is again held together by cables passed through apertures in the blocks.

It will be appreciated that blocks 10 and 100, and 50 and 150, may be exchanged within a revetment. In particular a revetment may comprise a lower portion formed from blocks 100 and 150 and an upper portion formed from blocks 10 and 50 It will be appreciated that revetments having the high weight to surface area which may be achieved with blocks of the present invention are particularly useful in sites where a surface is exposed to moderate to severe erosive forces and especially wave action,

Claims

CLAIMS: 1. A block shaped to interfit with corresponding blocks to form a surfacing on a surface and having contoured side surfaces to co-operate with contoured side surfaces of said corresponding blocks to resist relative displacement of the blocks in the plan of the surfacing, wherein the block is such that its weight per unit area of said surface covered is about 400kg/m2 or more.
2. A block as claimed in claim 1 wherein the block is made from concrete.
3. A block as claimed in claim I or claim 2, wherein the block is adapted to be secured to at least one further block, in use.
4. A block as claimed in claim 3, wherein the block is provided with a passage which, in use, receives an elongate element thereby to secure the block to at least one further block.
5. A block as claimed in claim 4, wherein the passage extends transversely to a contoured side surface.
6. A block as claimed in claim 5, wherein the passage extends substantially at right angles to the side surface.
7. A block as clabned I!I y of claims 4 to 6, wherein the block is provided with two such passages.
8. A block as claimed in claim 7, wherein the passages are parallel to each other.
9. A block as claimed in any of claims 4 to 8, wherein the elongate element is flexible and comprises cable or rope or the like.
10. A block as claimed in any preceding claim, wherein the contoured side surf aces comprise a V-shaped projection arranged to locate within a corresponding V-shaped recess in an adjacent block in the surfacing.
11. A block as claimed in claim 10, wherein the V-shaped projection extends over the height of the block,
12. A block as claimed in claim 10 or claim 11, wherein the block is provided with two such V-shaped projections on a side surface and two such v-shaped recesses on an opposite side surface thereof.
13. A block as claimed in any of claims 10 to 12, wherein in the case where a passage is provided, the passage extends through the block to emerge at the apex of a V-shaped projection and a V-shaped recess of the block.
14. A block as claimed in any preceding claim, wherein an end surface of the block is provided with a projection which is arranged to locate within a correspondingly shaped recess in another block.
15. A block as claimed in any preceding claim, wherein an upper surface of the block is formed with an irregular surface.
16. A block as claimed in claim 15, wherein, in the case of a concrete block, natural stone is set into the concrete whilst it is formed, so that in the finished block the stone stands proud of the concrete.
17. A block as claimed in any preceding claims, wherein an edge of the block comprises a surface transverse to the upper and side surfaces of the block.
18. A block as claimed in claim 17, wherein the edge surface comprises further distinct flat portions transverse to the upper and side surfaces.
19. A block shaped to interfit with corresponding blocks to form a surfacing on a surface, the block being substantially as hereinbefore described with reference to the accompanying drawings.
20. A surfacing comprising a plurality of interfitted blocks as claimed in any preceding claim.
21. A surfacing as claimed in claim 20 who rein, in the case where a passage is provided in each block for an elongate element, means is provided to tension the elements to hold the surfacing together.
22. A surfacing substantially as described herein before with reference to the accompanying drawings.