Classifications

• • E—FIXED CONSTRUCTIONS
  • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
  • E02B—HYDRAULIC ENGINEERING
  • E02B3/00—Engineering works in connection with control or use of streams, rivers, coasts, or other marine sites; Sealings or joints for engineering works in general
  • E02B3/04—Structures or apparatus for, or methods of, protecting banks, coasts, or harbours
  • E02B3/12—Revetment of banks, dams, watercourses, or the like, e.g. the sea-floor
  • E02B3/14—Preformed blocks or slabs for forming essentially continuous surfaces; Arrangements thereof

Definitions

• the invention refers to an assembly of concrete blocks for covering a dyke for protection against wave attacks, comprising at least two concrete blocks, each substantially having the form of a polygonal prism comprising a ground surface and a prism perimeter surface having a contiguous series of at least four side surfaces, in particular at least six side surfaces, in particular eight side surfaces, wherein the concrete blocks are placed at a distance from each other so as to form interstices between the blocks.
• the invention refers to a covering for a dyke for protection against wave attacks, comprising a plurality of concrete blocks arranged side by side, wherein the
• interstices between the blocks are filled with a granular material .
• Dyke bodies are exposed to heavy loads due to the movements of waves and/or water. Where the waves are too high or the current too strong for a grass cover, setting a stone covering provides an enhanced stability. It has been common practice to make such coverings of stone blocks by using so-called basaltic columns of natural stone, each column having a cross-sectional area differing from that of a further column. The stone columns have been placed against each other so that they support each other. This resulted in a relatively smooth dyke cover with a much greater stability, as if the stones had simply been poured loose on the embankment .
• blocks made of concrete instead of natural stone, such as basalt.
• Concrete blocks for use as a protection of water banks have been described, e.g., in WO 2011/096795 A2.
• Concrete blocks may be produced as precast elements, so that their production may be done in a cost-efficient way and under controlled manufacturing conditions .
• Concrete blocks are usually laid onto the dyke by means of machines, that grab and lay a plurality of blocks at once so as to increase the working speed. After the laying process, the interstices between the individual blocks are filled with granular material that holds the stones in their position relative to each other by
• the granular material ensures the permeability of the covering so that water can drain.
• a drawback of such a system is that the granular material arranged between the blocks is gradually washed out over time by the forces acting upon the granular material by the waves. As the granular material is washed out, the stability of the covering reduces substantially. Thus, there is a constant need to replace the granular material that has been washed out by new material, which involves high costs.
• a covering as described comprising a plurality of blocks with granular material being arranged in the
• Another known system for covering dykes comprises a number of blocks that interlock directly with each other in a form locking manner resulting in a very rigid and stable
• the instant invention aims at improving a concrete block coverage of a dyke for protection against wave attacks, that reduces the wash-out of granular
• the invention provides an improved assembly of concrete blocks comprising at least two concrete blocks, wherein said at least two blocks are interconnected by means of a connecting beam integrally formed with said at least two blocks, said connecting beam having a ground surface that is aligned with the ground surface of said at least two blocks and having a height that corresponds to 50-80%, preferably 65- 75%, of the height of said at least two blocks.
• connection beams divide the interstices into smaller compartments, which results in additional lateral barriers that hold the granular material in place. This minimizes the wash-out of the granular material, wherein the increased stability resulting therefrom enables to achieve well protected and stabilized dykes with blocks having a reduced height, therefore reducing the overall material cost of the
• the blocks Preferably, have a height of 30-40cm.
• the concrete blocks and connecting beams having a different height generate slopes, which help breaking the waves falling onto the dyke, thereby reducing the pressure of the waves .
• the height of the connecting beams is selected to be 50-80%, preferably 65-75%, of the total height of said at least two blocks, which proved to produce optimal results with regard to the prevention of a wash-out of granular material.
• the total height of a block is defined as the perpendicular distance between the ground area of the block and its highest point. If the at least two blocks that are
• connecting beams it is important to arrange the connecting beams so that their ground surface is aligned with the ground surface of said at least two blocks, so that the assembly, including the connecting beams, has a common ground area, which preferably is designed as a flat surface. Otherwise, granular material would tend to ingress into a gap formed between the connecting beams and the bedding layer, which would result in an undesired raising of the blocks.
• each concrete block of the block assembly is connected to the adjoining concrete block by means of a connecting beam of the type mentioned above.
• the invention provides an assembly of at least two concrete blocks that forms a rigid structure so that said assembly may be handled by a block laying machine in an easier way when compared to the handling of a corresponding plurality of loose blocks .
• the assembly comprises at least four concrete blocks arranged in a grid within a rectangular bounding box, each block substantially having the form of a polygonal prism comprising a ground surface and a prism perimeter surface having a contiguous series of at least four side surfaces, in particular at least six side surfaces, in particular eight side surfaces, wherein the concrete blocks are placed at a distance from each other so as to form interstices between the blocks, wherein two of said at least four blocks are each interconnected by means of a connecting beam integrally formed with said two blocks, said connecting beam having a ground surface that is aligned with the ground surface of said two blocks and having a height that corresponds to 50-80%, preferably 65- 75%, of the height of said two blocks.
• the assembly consists of exactly four blocks arranged in a 2x2 grid within a rectangular bounding box.
• Arranging the blocks of the assembly so that a rectangular bounding box is formed enables the placing of a plurality of such assemblies side by side in a regular pattern.
• the blocks have the shape of irregularly formed prisms, the polygonal base of the prism therefore having no symmetry and the edges of the polygonal base having
• the blocks are each formed as a right prism.
• the blocks of an assembly are shaped
• the assembly comprises a first group of blocks and a second group of blocks, the blocks of the first group having a larger prism perimeter than the blocks of the second group, wherein blocks of the first group and blocks of the second group are preferably arranged alternately.
• four connecting beams are provided each connecting two of said four blocks that are arranged consecutively along the direction of an edge of the bounding box.
• the concrete blocks are placed at a distance from each other so as to form interstices between the blocks. According to a preferred embodiment, this means that the blocks of the assembly do not touch each other except where they are connected by said connecting beams.
• An open area is defined as an area, in a plan view, of the assembly, in which the interstices between two adjoining blocks is open towards the bottom of the assembly so as to allow the free passage of water.
• the connecting beams are extending parallel to the edges of the bounding box.
• the percentage of an open area, in a plan view, defined as the sum of an area of the interstices present between the blocks of the assembly and the interstices present between the blocks of the assembly and the bounding box, with reference to the total area enclosed by the bounding box may be selected to be 10-15%, preferably, 12-13%.
• a preferred embodiment provides that two blocks that are interconnected by means of a connecting beam have opposed side surfaces confining at least one interstice between them, said opposed side surfaces extending in a non-parallel manner.
• interstice between two interconnected blocks narrows in one direction, which enhances the wedging effect and thus the friction between the granular material and the opposed side surfaces, said effect holding the granular material in place .
• two blocks that are interconnected by means of a connecting beam have opposed side surfaces confining a first interstice at one side of said connecting beam and a second interstice at the other side of said connecting beam, wherein the opposed side surfaces confining the first interstice are inclined relative to each other and the opposed side surfaces confining the second interstice are inclined relative to each other.
• Such an embodiment also results in the interstices having a narrowing geometry that increases the wedging of the granular material.
• the interstices in a plan view, are designed to allow a maximum free space between the blocks corresponding to a circle having a diameter of 50mm, preferably 40 mm.
• the bedding material comprises granular material that has a particle size of bigger than 40 or 50 mm
• the side surfaces of the blocks facing the outside of the assembly may taper inwardly from the bottom to the top, in order to facilitate the demoulding of the concrete block from the mould.
• each block preferably comprises a top surface and inclined surfaces each connecting an edge of the top surface with the side surfaces .
• the top surface has the shape of a rectangle that, in a top view, is arranged at an acute angle with respect to the bounding box.
• each pair of two blocks that are interconnected by means of a connecting beam has opposed side surfaces confining a first interstice at one side of said connecting beam and a second interstice at the other side of said connecting beam, whereby the first and the second
• interstice are each formed as an open space, to further decrease the tendency of the granular material to be washed out and to provide optimal pressure reduction of the waves falling onto the dyke.
• first and the second open space are open towards the respective side surface of the block.
• the concrete blocks are preferably made of a concrete that has a high compressive strength.
• the concrete blocks are preferably made of a concrete that has a high compressive strength.
• a covering for a dyke for protection against wave attacks comprising a plurality of assemblies of concrete blocks as described above that are arranged side by side, wherein the interstices between the blocks of each assembly and the interstices between adjoining assemblies are filled with a granular material.
• the side by side arrangement is configured such that the blocks of one assembly rest against the blocks of the adjoining assembly, thereby increasing the overall stability of the covering.
• the assemblies of concrete blocks are arranged on a filter layer comprising a granular material, said filter layer preferably being arranged on a geotextile and said geotextile preferably being arranged on a layer of clay .
• the granular material arranged within the interstices has a particle size of between 4 and 32 mm, preferably 16 and 32 mm.
• a granular material having a particularly high mass is used.
• the granular material arranged within the interstices has a volumetric mass density of > 2' 800 kg/m 3 , preferably 2' 900-3' 000 kg/m 3 .
• the granular material arranged within the interstices is made of crushed or broken stone, preferably basalt.
• Crushed or broken stone is characterized by an irregular shape, which enhances the interlocking effect prevailing between the stones.
• the granular material of the filter layer has a particle size distribution characterized by a D90 > 50 mm.
• interstices between the blocks of each assembly and the interstices between adjoining assemblies are dimensioned so as to prevent ingression of the granular material of the filter layer.
• inventive covering and the inventive assembly of blocks can not only be used for covering dykes, but for covering any water-exposed slopes in general, such as banks, coasts, etc .
• FIG. 1 shows a
• FIG. 2 is a top view of the assembly of Fig. 1
• Fig. 3 is a sectional view along the line A-A of Fig. 2
• Fig. 4 is a sectional view along the line B-B of Fig. 2
• Fig. 5 is a sectional view along the line C-C of Fig. 2
• Fig. 6 is a top view of a plurality of assemblies of Fig. 1 arranged side by side
• Fig. 7 is a sectional view of a dyke with an inventive covering.
• Fig. 1 illustrates an assembly 1 of four concrete blocks 2, 3, 4 and 5.
• the blocks are each formed as right prisms having an irregularly formed polygonal ground surface 6 and a prism perimeter surface having a contiguous series of eight side surfaces 7.
• the blocks have a rectangular top surface 8 that extends parallel to the ground surface 6.
• the top surface 8 is smaller than the ground surface 6, wherein inclined surfaces 9 each connect an edge of the top surface 8 with two adjoining side surfaces 7.
• the concrete blocks are placed at a distance from each other so as to form interstices 10 and 11 between the blocks, as can be seen in the top view according to Fig. 2.
• the blocks 2, 3, 4 and 5 are arranged in a grid of 2x2 blocks, wherein adjoining blocks are each interconnected by means of a connecting beam 12, 13, 14 and 15.
• blocks 2 and 3 are interconnected by a
• connecting beam 13 and blocks 3 and 4 are interconnected by a connecting beam 14, and blocks 4 and 5 are
• diagonally arranged blocks 2 and 4 are smaller than the diagonally arranged blocks 3 and 5.
• a first group of interstices 10 is formed on the exterior side of the connecting beams and a second group of
• interstices 11 is formed on the interior side of the connecting beams, wherein the interstices 11 are joined to form a single central compartment.
• the blocks 2, 3, 4 and 5 of assembly 1 are arranged within the rectangular bounding box 16, which facilitates the arrangement of a plurality of assemblies 1 as depicted in Fig. 6.
• the assemblies 1 are placed side by side in a manner that adjoining assemblies rest against each other except of block 4, which comprises a lateral extension beam 17, which rests against block 3 of an adjoining assembly.
• block 4 which comprises a lateral extension beam 17, which rests against block 3 of an adjoining assembly.
• interstices 18 are formed between the blocks of adjoining assemblies 1. Further, Fig. 6 shows that the blocks of adjoining assemblies interlock with each other by having edges of the blocks of one assembly extending into the bounding box of an adjoining assembly.
• the open area of the dyke covering that is formed by the plurality of assemblies 1 is defined as the percentage of the accumulated areas, in a top view, of the interstices 10, 11 and 18, with reference to the total area covered by the assemblies or their bounding boxes respectively. In the present example, the open area is 12.35 %.
• the open area in a top view, is shaped so as to prevent the granular material of a filter layer arranged below the blocks from entering into the interstices. Therefore, the interstices 10, 11, and 18 allow for a maximum free space between the blocks corresponding to a circle having a diameter of d, as shown in Fig. 2, which in the present example is 50 mm.
• the connecting beams are integrally formed with the blocks that they interconnect and have a ground surface that is aligned with the ground surface of the blocks. Further, the connecting beams have a height that corresponds to 50-80%, preferably 65-75%, of the height of the blocks, as can been seen in the cross sectional view according to Fig. 3. The same applies for the lateral extension beam 17 as shown in Fig. 4.
• Fig. 5 illustrates that the transition from a connecting beam 12 to the adjoining concrete blocks 2 and 5 is formed by a sharp edge x, i.e. a right angle. The same applies to the other connecting beams 13, 14 and 15 and for the extension beam 17.
• Fig. 7 illustrates a dyke 19 that has a covering consisting of a base layer 20 of clay, a geotextile arranged on the layer 20, a filter layer 21 consisting of a granular bed material and a layer 22 of assemblies 1 of blocks.
• the covering as shown in Fig. 7 was subjected to the following stability test.
• the test was conducted in an artificial testing facility having a flume that is 300 m long, 5 m wide and 9.5 m deep. Waves can be generated with a significant wave height of up to 2 m, with individual highest waves up to 5 m.
• the stability of the covering in wave attacks must be tested on a large scale, because the damage mechanism is highly influenced by scale effects.
• the objective of the investigation was to determine the stability factor of the inventive covering.
• Test 1 short duration tests with small wave steepness (relatively low waves)
• Test 2 short duration test with large wave steepness
• Test 3 long duration test with large wave steepness
• the wave height has been increased step-by-step, starting at a significant wave height of 1.5 m and ending at 1.9 m. These were short duration tests of approximately 1.5 hours each (at least 1000 waves ) .
• the third test series was a long duration test, lasting 26 hours .

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• Engineering & Computer Science (AREA)
• General Engineering & Computer Science (AREA)
• Environmental & Geological Engineering (AREA)
• Ocean & Marine Engineering (AREA)
• Mechanical Engineering (AREA)
• Civil Engineering (AREA)
• Structural Engineering (AREA)
• Revetment (AREA)

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• 2018
  • 2018-10-03 EP EP18000784.1A patent/EP3633108A1/de not_active Withdrawn
• 2019
  • 2019-10-02 WO PCT/IB2019/058370 patent/WO2020070656A1/en active Search and Examination
  • 2019-10-02 EP EP19780443.8A patent/EP3861172A1/de active Pending
  • 2019-10-02 MA MA053805A patent/MA53805A/fr unknown

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