NL2034112B1 - Wave/water-retarding slope - Google Patents
Wave/water-retarding slope Download PDFInfo
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- NL2034112B1 NL2034112B1 NL2034112A NL2034112A NL2034112B1 NL 2034112 B1 NL2034112 B1 NL 2034112B1 NL 2034112 A NL2034112 A NL 2034112A NL 2034112 A NL2034112 A NL 2034112A NL 2034112 B1 NL2034112 B1 NL 2034112B1
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- Prior art keywords
- slope
- revetment
- blocks
- wave
- water
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- 239000004746 geotextile Substances 0.000 claims abstract description 220
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 115
- 239000013049 sediment Substances 0.000 claims abstract description 68
- 230000000979 retarding effect Effects 0.000 claims description 45
- 238000000034 method Methods 0.000 claims description 14
- 239000004576 sand Substances 0.000 claims description 13
- 239000004927 clay Substances 0.000 claims description 9
- 238000000926 separation method Methods 0.000 claims description 5
- 239000003365 glass fiber Substances 0.000 claims description 4
- 239000004575 stone Substances 0.000 claims description 3
- 239000002131 composite material Substances 0.000 claims description 2
- 230000000284 resting effect Effects 0.000 claims 1
- 238000010276 construction Methods 0.000 description 47
- 239000000463 material Substances 0.000 description 10
- 230000005012 migration Effects 0.000 description 6
- 238000013508 migration Methods 0.000 description 6
- 238000002474 experimental method Methods 0.000 description 5
- 238000005406 washing Methods 0.000 description 5
- 239000002689 soil Substances 0.000 description 3
- 238000005243 fluidization Methods 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 230000003313 weakening effect Effects 0.000 description 2
- 235000005505 Ziziphus oenoplia Nutrition 0.000 description 1
- 244000104547 Ziziphus oenoplia Species 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 239000005445 natural material Substances 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 230000002787 reinforcement Effects 0.000 description 1
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
- E02B3/10—Dams; Dykes; Sluice ways or other structures for dykes, dams, or the like
-
- 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
-
- 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
Landscapes
- 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)
Abstract
The present invention relates to a wave/water-retarding slope. The slope comprises: a slope body 1 defining a slope surface 2; a revetment 11 of revetment blocks arranged on the slope surface 2; and an intermediate layer between the slope surface 2 and the revetment 11. The revetment has a wave/water-retarding open structure The slope body 1 is made of a sediment having a grain size of at most 2 mm. The intermediate layer comprises a geo-textile 5 having a land side and water side. The land side faces to the slope body 2 and the water side contacts the revetment blocks. The geo-textile 5 separates the sediment and revetment blocks from each other and allows water to pass through the geo-textile. The geo-textile 5 has a tensile strength of at least 80 kN/m, and a strain of at most 5%, when subjected to a tensile load of 80 kN/m.
Description
P35904NL00
Title: Wave/water-retarding slope
The invention relates to the field of wave/water-retarding slopes. In general, wave/water- retarding slopes are used in land-backed constructions (i.e. constructions with water on one side and land on the other side) extending along the shore of a sea, lake etcetera or along the bank of a river, canal etcetera.
A wave/water retarding slope retards waves and/or water. Similar a wave/water retarding construction retards waves and/or water. Wave/water-retarding slopes have an open structure designed to absorb the energy of water and/or waves — when the water respectively waves hit the open structure of the slope, — when the water respectively waves flow along open structure of the slope, — when the water respectively waves flow through the open structure of the slope.
Wave/water-retarding slopes thus reduce the forces of the waves and/or water by retarding the waves and/or the flow of water. The wave/water-retarding slope according to the invention may be used with any type of water (sea, lake, river, canal, etcetera) and in any type of land- backed wave/water-retarding construction having — inherent to its wave/water-retarding function — an open structure at its slope.
Wave/water-retarding slopes are, in general, the effective part of a land-backed wave/water- retarding construction, like a wave/water-retarding dike or wave/water-retarding bank. The wave/water-retarding slope according to the invention is provided at the water facing side of the wave/water-retarding construction. The wave/water-retarding slope according to the invention is the water facing part of a wave/water-retarding construction, i.e. the part in contact with the water and breaking the energy of the water and/or waves.
In land-backed wave/water-retarding constructions, stone-like blocks and sediments of all kinds of sizes may be used.
In general, sediments are classified by their grain size, also called particle size. Well known classifications are the Wentworth scale (or Udden-Wentworth scale) or the Krumbein phi (2) scale, which is a logarithmic scale created by Krumbein in 1934 as a modification of the
Wentworth, see the below table 1 on the next page. Further elaborating on, among other things, the scales of Wentworth and Krumbein, ISO 14688-1:2017 (E) provides ‘sediment grain size ranges’ in mm in relation to the classification according to the ‘Wentworth grades’ and ‘Phi (©®) scale’, respectively, see the below table 2 on the next page, which is identical to ‘table 1 in section 5.1.1 of ISO 14688-1:2017 (E).
A wave/water-retarding construction — both a conventional one as well as one according to the invention - comprises a slope body which defines the gradient of the slope and has a slope surface extending, relative to the horizontal plane, at a slope surface angle corresponding to the gradient of the slope. This slope body is covered with i) a revetment of stone-like revetment blocks providing the open structure configured for wave/water-retarding and ii) one or more intermediate layers between the revetment and the slope surface. In conventional constructions the one or more intermediate layers comprise at least two intermediate layers, whilst according to the invention the one or more intermediate layers may be just one intermediate layer.
In conventional wave/water-retarding slopes, the revetment consists of large stone-like revetment blocks of natural stone or concrete, which are placed on a so called filter layer arranged between revetment and a geo-textile on the slope body, the filter layer and geo- textile both being a said intermediate layer. This filter layer in general consists of two said intermediate layers: — atop layer of riprap (also known as rubble) - having in general a size of about 60-350 mm, i.e. in the range of Wentworth grade ‘cobble’ - and — a lower layer of gravel — having in general a size of about 8-32 mm, i.e. in the range of
Wentworth grades ‘medium gravel’ and ‘coarse gravel -.
The conventional filter layer serves to protects the geotextile from being ruptured by the revetment, to keep the geotextile in place, and to slow down water hitting the wave retarding construction in order to prevent waves and water from being pressed through the geotextile.
The slope body may - conventionally as well as according to the invention - comprise any material suitable, like sand or clay.
When constructing a conventional wave/water-retarding slope this involves not only transporting multiple tons of revetment blocks to their destination, but also transporting multiply tons of riprap and gravel. This transport is quite costly and time consuming when it is not (ready) available and has to come from far.
mm grade medium gravel -3t0 -4 >4 08 sand very fine silt 8107
Table 1. [ symbol ] mm
BN large boulder [ IBo |] very coarse soil u boulder [ Bo ] cobble [Co] > 63 to < 200 coarse soil sand[Sal [>0063t0s20
Sit [si] coarse silt [ ¢Si fine soil medium silt [ mSi fine silt [ fSi] > 0.002 to < 0.063
Table 2: clay [CI]
It is an object of the invention to provide an alternative wave/water-retarding slope for a land- backed construction. A further object of the invention is providing a wave/water-retarding slope overcoming one or more of the problems associated to conventional wave/water- retarding slopes.
C1: One or more of the above objects are according to a first aspect of the invention achieved by providing a wave/water-retarding slope, comprising: — a slope body defining a slope surface; — arevetment of stone-like revetment blocks, such as concrete revetment blocks, arranged on the slope surface and configured to provide a wave/water-retarding open structure; and — an intermediate layer between the slope surface and the revetment blocks; wherein the slope body is made of a sediment having a grain size of at most 2 mm; and wherein the intermediate layer comprises a geo-textile having a first surface side — which is further called land side face - and a second surface side — which is further called water side face - the land side face facing to the slope body and the water side face being on the one hand exposed to openings of the open structure and on the other hand in contact with contact surfaces of the revetment blocks; and wherein the geo-textile has a tensile strength of at least 80 KN/m, and a strain of at most 5%, such as at most 3%, when subjected to a tensile load of 80 KN/m.
In case the land-backed construction is a dike, the slope body may — according to the invention - be the so called dike body. In case the land lies substantially higher than the water, a dike may be absent and the land-backed construction may be a bank and the slope body may — according to the invention - be the part of the bank adjacent the water. This part may have an about triangular cross-section with an about vertical and an about horizontal side and a slanting side corresponding to the slope surface. According to the invention it is also possible that the slope body is a slanting layer with for example an about constant thickness in horizontal direction. For example in case a bank has already a natural or artificial slant or in case of natural or artificial dam or dike, the slope body may — according to the invention - be a slanting sediment layer arranged or already present on the bank or dike/dam.
The slope body is mainly constructed from {or built up from) a sediment having a grain size smaller than 2 mm. Such sediments are quite prone for being washed out by water. It is as such known that geo-textiles may help preventing this.
In terms of ISO 14888-1:2017, a sediment having a grain size of at most 2 mm, is a sediment smaller than ‘fine gravel (fGr)’. In terms of Wentworth grade, a sediment having a grain size of at most 2 mm is a sediment having a grade smaller than ‘very fine gravel’, which corresponds to a Krumbein’s Phi (®) scale of larger than *-1°. 5
Similar as in prior art, geo-textile is used to keep two layers on opposite sides of the geo- textile separated from each other. With the invention, these two separated layers are the sediment of small grain size (< 2mm), on the one hand, and the revetment blocks of large dimensions, on the other hand. For dry sediment this separation works well, but under aqueous conditions when the construction according to the invention is subjected to high water and/or heavy weather this separation may not be 100%. So one may say that the geo- textile used in the invention is configured to separate the revetment blocks and sediment from each other in at least a dry condition or non-aqueous condition of the sediment (because it may not be 100% in aqueous condition).
As is known from prior art and may also be the case with the invention: — a geo-textile in a wave-retarding slope should allow water to escape from the slope body through the geo-textile, i.e. backflow-water is allowed to pass through the geo-textile from the land side to the water side, — backflow-water dragging along fine sediment parts from the slope body through the geo- textile may be counteracted but is difficult to prevent completely.
When water enters into the slope body then i) sediment of small grain size may tend to escape from the wave/water-retarding slope, and ii} the water entered may cause fluidisation of the sediment with small grain size. Due to this fluidizing of the sediment with small grain size, the revetment blocks may so to say sink into the slope body. In conventional wave/water-retarding slopes, this is counteracted by the filter layers between the revetment and the geo-textile. The (conventional) filter layers function as a buffer preventing the geo- textile from being exposed directly to the water/waves. Further the (conventional) filter layers reduce the flow rate of backflow-water passing from the slope body, through the geo-textile, to the revetment blocks so that this backflow-water is less-likely to drag along fine sediment parts from the slope body through the geo-textile.
As the revetment of revetment blocks puts a lots of weight on the geo-textile and consequently loads the geo-textile heavily, the geo-textile may easily damage or rupture.
Such damage or rupture will result in sediment escaping from the wave/water-retarding slope and consequently weakening of the wave/water-retarding slope and possibly flooding or other disasters. With respect to the revetment blocks loading the geo-textile, it is to be noted that in wave/water-retarding slopes the revetment blocks may also be moved by the forces of the water, which results in the geo-textile being additionally subjected to loads which may cause the geo-textile to be damaged or rupture. Conventionally, this is solved by placing gravel and riprap as an intermediate construction between the revetment blocks and the geo-textile so that the revetment blocks rest on the riprap, the riprap rests on the gravel, and the gravel rests on the geo-textile. This conventional construction prevents the revetment blocks from directly contacting the fragile geo-textile and spreads the load of the revetment blocks over the geo-textile so that the geotextile is kept well pressed against the sediment everywhere and so that local peaks in loads on and in the geo-textile are reduced. The inventor(s) surprisingly found that i) the intermediate construction of riprap and gravel may very well dispensed with provided that the geo-textile has a sufficient tensile strength in combination with a low strain when tensile loaded, and that ii) for this purpose known geo-textiles of — compared to what is known in the field of geotextiles — relatively moderate strength are already suitable. Without being bound by any scientific theory, it is believed that the low strain prevents the geo-textile from becoming permanently stretched by — amongst others — the load of revetment blocks and impact of water/waves. A permanent stretch of the geo-textile would cause the geo-textile to lengthen locally which in turn causes slackening of the geo-textile which may result in flapping of the geo-textile under influence of waves and moving water. In other words, the low strain ensures that the geo-textile is kept taut against the sediment of the slope body, which apparently counteracts fluidization of sediment of the slope body sufficiently. All in all, while the view according to the prior art is that in wave-retarding slopes one or more filter layers are necessary between the revetment blocks and the geo-textile, this appears — according to the invention - not to be necessary. When the geotextile has a tensile strength of at least 80 kN/m in combination with a strain of at most 5%, such as at most 3%, when subjected to a tensile load of 80 kN/m, then the revetment may lie directly on the geo- textile without any intermediate layer. Here, tensile strength and strain may be measured according to EN ISO 10318.
As a result of the revetment lying directly on the geo-textile, the water side face of the geo- textile — i.e. the surface side of the geo-textile which faces the revetment — is on the one hand exposed to openings of the open structure and on the other hand in contact with contact surfaces of the revetment blocks. In other words, part of the water side face is in contact with the contact surfaces of the revetment blocks — a contact surface of a revetment block being the surface of the revetment block which rests on the geo-textile -, and another part of the water side face, which part is free of contact with the revetment blocks is exposed to the openings of the open structure. This other part of the second surface part faces so to say directly into the openings of the open structure.
Dispensing with the intermediate construction of riprap and gravel results in significant material savings, significant savings in transportation costs, significant reduction of work during construction of the wave/water-retarding slope, significant reduction of materials used, etcetera. On top of this comes that riprap and gravel are not always readily available.
C2: In order to counteract the sediment of small grain size from escaping through the geo- textile and to prevent the revetment blocks from sinking into the slope body, the geo-textile may according to a further embodiment of the first aspect be configured to keep the revetment blocks and sediment separated from each other, at least when the sediment is in dry condition. As in wave/water-retarding slopes, water may very well enter into the slope body (which may as such result in weakening of the slope body), water is allowed to pass through the geo-textile from at least its first surface facing the slope body to its water side face facing the revetment blocks in order to ensure the water can be drained off from the slope body. Optionally, the water may also be allowed to pass in the opposite direction as well, i.e. from the water side to the land side.
Surprisingly, the problem of washing out fine sediment parts by being dragged along with backflow-water through the geo-textile also does not occur, at least not nearly in the amount as expected when leaving away the filter layers which in conventional constructions serve to reduce this washing out.
C3: According to a further embodiment of the first aspect of the invention, each contact surface defines a corresponding contact area on the geo-textile, in which contact area the geo-textile contacts a revetment block. In this respect it is to be noted that not all revetment blocks have to be in contact with the geo-textile. This may for example be the case when the revetment blocks are arranged randomly with one or more revetment blocks, or even an entire layer of revetment blocks being supported on other revetment blocks and not contacting the geo-textile. Further, the part of a revetment block contacting the geo-textile — i.e. the contact surface — may be any part of the revetment block and thus does not have to be predefined part of the revetment block. In case the contact surfaces are predefined surfaces of the revetment blocks, these contact surfaces may extend about parallel to the slope surface or geo-textile.
C4: According to a further embodiment of the embodiment in which each contact surface defines a contact area, the distance between adjacent contact areas is at most about 90 cm, such as at most about 80 cm.
By ensuring that the distance between two adjacent contact areas is at most about 80 cm, it is further ensured that the geo-textile is kept sufficiently taut against the sediment of the slope body at the areas where the geo-textile is exposed to the openings of the open revetment structure. The smaller this distance between adjacent contact areas, the better the tautness of the of the geo-textile against the sediment will be. In embodiments this distance may be further reduced to at most about 80 cm, such as at most in the range of 70 cm to 80 cm.
C5-8: According to a further embodiment of the embodiment in which each contact surface defines a contact area, the distance between adjacent contact areas is, viewed along the slope surface and in a horizontal direction or a direction transverse to the horizontal, at least about 30 cm, such as at least about 40 cm. According to a further embodiment the distance between adjacent contact areas the may be in the range of about 40 cm to about 20 cm or in the range of about 40 cm to about 80 cm, respectively. Accordingly, the revetment blocks may be placed on the geo-textile in such manner that the contact areas of adjacent revetment blocks are spaced with respect to each other, the distance — which might be a largest distance - between each pair of adjacent contact areas being in the range of 40-90 cm or in the range of 40-80 cm. So, in first example, the revetment blocks may be placed on the geo- textile in such manner that: — viewed parallel to the slope surface and in a horizontal direction, the contact areas of each pair of adjacent revetment blocks have a distance in the range of 40-90 cm, and — viewed parallel to the slope surface and in a direction transverse to the horizontal, the contact areas of each pair of adjacent revetment blocks have a distance in the range of 40-90 cm; and, in a second example the revetment blocks may be placed on the geo-textile in such manner that: — viewed in a horizontal direction along the slope surface, the contact areas of each pair of adjacent revetment blocks have a distance in the range of 40-80 cm, and viewed in a direction along the slope and transverse to the horizontal the slope surface, the contact areas of each pair of adjacent revetment blocks have a distance in the range of 40-80 cm.
By ensuring that the distance between two adjacent contact areas is at most least 40 cm, it is further ensured that a sufficient backflow (which is required to allow water to escape from the slope body) is maintained and that this backflow is not too much decreased due to the parts of the geotextile exposed to the openings of the open structure becoming small. As said above, this backflow is of importance to ensure that water is allowed to escape from the slope body. (7-8: According to a further embodiment of the embodiment in which each contact surface defines a contact area, the sum of said contact areas is in a range of between about 5% to about 60% of the water side face of the geo-textile. In this embodiment, the rest of the water side face of the geo-textile may be exposed to openings of the open revetment structure. In other words about 5% to about 60% of the water side face of the geo-textile is a said contact area, while the rest of the water side face may be exposed. All contact surfaces together thus overlap about 5% to about 60% of the water side face of the geo-textile, and the rest of the water side face of the geo-textile may be left exposed. When too large a part of the water side face of the geotextile is contacted by contact surfaces - i.e. when the sum of all contact areas becomes too large with respect to the water side face -, the ability of the slope to dewater becomes too small and the wave/water retarding effect may decrease (too much). Lab experiments have revealed that this seems to be the case when substantially more than 55% of the second side of the geo-textile is contacted by contact surfaces. Lab experiments further revealed that flapping of the geotextile, under (simulated) normal circumstances of heavy weather, seems to be prevented very well when the sum of said contact areas is in the range of about 35% to about 60% of the water side face of the geo-textile. The sum of said contact areas may according to a further embodiment be in the range of about 40% to about 50% and may according to another further embodiment be in the range of about 45% to about 50%.
When the percentage for the sum of contact areas becomes too small, then a risk of tearing of the geo-textile may be introduced. Lab experiments revealed however that when this percentage is in the range of about 5% to about 10% of the water side face of the geo-textile, the degree of tearing and the degree of flapping may, depending on requirements and circumstances, still be acceptable.
C9-10: According to a further embodiment of the first aspect of the invention, the grain size of the sediment is at most 1 mm, such as at most 0.63 mm.
In terms of Wentworth grade, a sediment with grain size of at most 1 mm is a sediment having a grade smaller than ‘very coarse sand’, which corresponds to a Krumbein’s Phi (®) scale of larger than ‘0’. In terms of ISO 14688-1:2017, a sediment having a grain size of at most 0.63 mm is a sediment smaller than ‘Coarse sand (cSa)’, which, in terms of Wentworth grade, is about the same as a sediment having a grade smaller than ‘coarse sand’, which corresponds to a Krumbein’s Phi (®) scale of larger than ‘1’. Medium and even fine sand, and also finer sediments, like silt and clay, are sediments which in general are readily available and may very well form the basis of a slope body according to the invention.
C11-12: According to another further embodiment of the first aspect of the invention, the tensile strength of the geo-textile may be at least 90 kN/m, such as at least 100 kN/m or at least 250 kN/m or at least 500 kN/m. According to still another further embodiment of the first aspect of the invention, the strain of the geo-textile is at most 3%, such as at most 2%, when subjected to a tensile load of 90 kN/m. Applicant found for example that Polyfelt® PGM-
G 100/100 of TenCate® may very well be used as geo-textile in a wave/water-retarding slope according to the invention. This Polyfelt PGN 100/100 has a tensile strength of about 100 kN/m (EN ISO 10319), a 2% strain at 90 kN/m (EN ISO 10319) and an elongation at break of 3% (EN ISO 10319).
C13-15: According to another further embodiment of the first aspect of the invention: — the geo-textile may be a geotextile reinforced with interwoven glass fibres, such as a grid of interwoven glass fibres; and/or — the geo-textile may be a composite of a geo-textile layer with a reinforcement geo-grid, like for example PW4-LA of Terram®; and/or — the geo-textile may be a reinforced trackbed separator, for example PW4-LA of Terram®.
C16: According to another further embodiment of the first aspect of the invention, the intermediate layer may further comprise a gravel layer arranged between the geo-textile and the slope surface, the gravel layer having, transverse to the slope surface, a thickness in the range of 5-15 cm, such as about 10 cm, and having a grain size in the range of 4-32 mm.
Such gravel layer further assists in preventing sand or clay sediment of the slope body from being washed out. Especially in case of steep slope surfaces, this may be useful. In this embodiment, the land side face of the geo-textile may lie on one side of the gravel layer and may contact that side, whilst the other side of the gravel layer may lie on the slope body in contact with the slope body. The gravel layer thus is provided at the backside or landside of the geo-textile.
C17: According to another further embodiment of the first aspect of the invention, the intermediate layer may consist of or be formed by the geo-textile. The geo-textile then directly lies on the slope body in contact with the slope body, without a gravel layer in between.
C18: According to another further embodiment of the first aspect of the invention, the slope body has, viewed transverse to the slope, a thickness of at least 0.5 meters (=50 cm), such as at least 1 meter or at least 1.5 meter or at least 2 meters. (C19: According to another further embodiment of the first aspect of the invention, revetment blocks according to applicant's earlier WO-2018/052292 may be used in a wave/water- retarding slope according to the invention. A revetment block according or similar to WO- 2018/052292 is constituted by: — acentral part; — a pair of wings projecting in mutually opposite directions from the central part, in horizontal direction, and parallel to the slope surface; — a nose projecting from the central part transverse to the wings, in horizontal direction, and away from the slope surface; and — a tail projecting from the central part transverse to the wings, in horizontal direction, and towards the slope body.
These revetment blocks may be arranged in rows with in each row the wings of the revetment blocks aligned along an about straight axis. Multiple of these rows may be stacked obliquely along the slope, with an upper row (obliquely) above an adjacent lower row. The nose of a said revetment block of the upper row may be supported on the ends of two aligned wings of adjacent said revetment blocks of the lower row, and the tail of a said revetment block of the lower row supports the ends of two aligned wings of adjacent said revetment blocks of the upper row. This manner of arranging the revetment blocks obliquely along the slope results in revetment with a regular pattern of revetment blocks, in which the upper revetment blocks press an the lower revetment blocks, resulting in turn in a solid revetment with large openings for absorbing wave/water energy.
In this further embodiment with revetment blocks according or similar to WO-2018/052292, the end of each tail forms a said contact surface, which contact surface is provided at the land facing outer end of each tail. This contact surface rests on the geo-textile and defines a corresponding contact area of the geo-textile. This contact surface may extend about parallel to the slope surface or geo-textile.
C20-22: In order to reduce or prevent flapping further: — the contact surfaces contacting the geo-textile may be configured such that the part of the water side face of the geo-textile which is in contact or overlap with the contact surfaces forms a lattice like pattern of cross-wise lattices surrounding free parts of the water side face of the geo-textile;
and/or — the contact surface of said revetment blocks my be configured such that all contact surfaces together overlap with at least about 5% to about 60%, such as at least about 10 % to about 60%, of the water side face of the geo-textile; anor — the contact surface of said revetment blocks may be configured such that all contact surfaces together contact (or overlap with) about 35% to about 60%, such as in one embodiment about 40% to about 55% or in another embodiment about 45% to about 50%, of the water side face of the geo-textile.
C23-24: Further according to a further embodiment of the first aspect, the revetment blocks may have dimensions comparable or corresponding to a grain size of at least 300 mm, such as at least 500 mm or larger. As an alternative to or in addition to using grain size, the dimensions of the revetment blocks may according to (a further embodiment) of the invention also be expressed as having a nominal diameter in the range of 30-110 cm, such as a nominal diameter of about 45 cm or about 80cm. Here, the nominal diameter is defined as the cube root of the volume of a block, i.e. nominal diameter = (volume block)
C25: According to a further embodiment of the first aspect, the revetment blocks may be blocks of any material, like a natural material such as for example basalt or an artificially made material such as for example concrete. According to an example, these revetment blocks may be placed randomly on the slope body. According to another example, these revetment blocks may be placed in a regular pattern on the slope body, like for example the revetment blocks and patterns as are known from and described in applicant's earlier WO- 2018/052292.
C26: According to a second aspect of the invention, one or more of the above objects are achieved by providing a stone-like revetment block for a revetment, such as a stone-like revetment block for a revetment in a wave/water retarding slope according to the first aspect of the invention. The revetment block according to the second aspect of the invention may however also be used in other constructions, for example constructions having one or more intermediate layers, like conventional layers, between the revetment and the geo-textile, or having no geotextile at all, or being not land-backed. The stone-like revetment block according to the second embodiment is constituted by: — a central part, — a pair of wings projecting in mutually opposite horizontal directions from the central part,
— a nose projecting from the central part transverse to the wings, in a horizontal forward direction, and — a tail projecting from the central part transverse to the wings, in a horizontal backward direction; wherein the end of the tail is provided with a contact surface extending at a contact surface angle with respect to a horizontal surface defined by: i) the opposite horizontal directions in which the wings extend, ii) the horizontal forward direction, and iii) the horizontal backward direction; wherein the contact surface is configured such that, when a plurality of horizontal rows of said revetment blocks is arranged on the slope surface, with — viewed along the slanting slope direction, an upper row of said horizontal rows of revetment blocks being arranged obliquely above an adjacent lower row of said horizontal rows of revetment blocks, — in each row, the wings of the revetment blocks being aligned, — the nose of a said revetment block of the upper row being supported on the ends of two aligned wings of adjacent said revetment blocks of the lower row, — the tail of a said revetment block of the lower row supporting the ends of two aligned wings of adjacent said revetment blocks of the upper row, the sum of the contact surfaces of the tails of the revetment blocks is in the range of 35% to about 60% of the slope surface covered by the plurality of horizontal rows arranged on the wave retarding slope.
One of the wings may extend in a right horizontal direction and the other of the wings may extend in a left horizontal direction. Per row the wings of the revetment blocks are aligned, i.e. the right wing of each block pointing to the left wing of the block adjacent on the right and the left wing of each block pointing to the right wing of the block adjacent on the left. Optionally, the free end of the right wing of each block may abut against the free end of the left wing of the block adjacent on the right and the free end of the left wing of each block may abut against the free end of the right wing of the block adjacent on the left.
The said configuration of the contact surfaces such that the sum of the contact surfaces of the tails of the revetment blocks is in the range of 35% to about 60% of the slope surface covered by the plurality of horizontal rows arranged on the wave retarding slope, may, more specifically, be a configuration of each contact surface relative to the associated block (or a configuration of the contact surfaces relative to the blocks).
Also without geo-textile or with other layers in between the revetment and the geo-textile, the contact surface being relatively large with respect to the rectangular surface provides that the layer(s) below the revetment are kept solid and in place. (C27: According to a further embodiment of the second aspect, the sum of the contact surfaces of the tails may be in the range of about 40% to about 55% of the slope surface covered by the plurality of horizontal rows arranged on the wave retarding slope.
C28: According to another further embodiment of the second aspect, the sum of the contact surfaces of the tails may be in the range of about 45% to about 50% of the slope surface covered by the plurality of horizontal rows arranged on the wave retarding slope.
C29: According to another further embodiment of the second aspect, the contact surfaces of each pair of adjacent blocks may, viewed parallel to the slope surface and in a horizontal direction, have a distance in the range of 40-90 cm, such as in the range of 40-80 cm, and the contact surfaces of each pair of adjacent blocks may, viewed parallel to the slope surface and in a direction transverse to the horizontal, have a distance in the range of 40-90 cm, such as in the range of 40-80 cm.
C30: According to another further embodiment of the second aspect, the contact surface angle may be in the range of about 18° to about 33°, such as in the range of about 20° to about 28°.
C31: According to another further embodiment of the second aspect, the slope surface defines a slope angle with respect to the horizontal plane, and contact surface angle is (about) the slope angle.
C32: According to another further embodiment of the second aspect, the revetment block may be a concrete revetment block.
C33-34: According to a third aspect of the invention, one or more of the objects of the invention are achieved by the use of a reinforced trackbed separator in a slope body as an intermediate layer between a revetment of revetment blocks with dimensions corresponding to a grain size larger than 300 mm, such as at least 500 mm, and a slope body of a sediment having a grain size of at most 2 mm, such as at most 1 mm. Alternatively to or in addition to defining the dimensions of the revetment blocks in terms of a grain size, the dimension of the revetment blocks may also be defined in terms of a nominal diameter in the range of 30-60 cm, the nominal diameter is defined as the cube root of the volume of a block, i.e. nominal diameter = (volume block). The reinforced trackbed separator may according to the second aspect have the characteristics of the geo-textile in the first aspect of the invention. (C35-37: According to a fourth aspect of the invention, one or more of the objects of the invention are achieved by providing a method of making a wave/water-retarding slope, comprising the steps: a) providing a slope body made of a sediment having a grain size of at most 2 mm, the slope body defining a slope surface;
Db) applying an intermediate layer with a geo-textile along the slope surface, the geo-textile having a land side face and a water side face, the land side face facing the slope surface and optionally flush with the slope surface, the water side face facing in a direction opposite to the slope surface; c) placing a revetment of stone-like revetment blocks, such as concrete revetment blocks, onto the water side face of the geotextile, the revetment blocks having dimensions corresponding to a grain size of at least 300 mm, such as at least 500 mm and providing wave/water-retarding open structure; wherein, according to an optional further embodiment, the geo-textile is configured to keep the sediment and revetment blocks separated from each other whilst allowing water to pass through the geo-textile; and wherein the geo-textile has a tensile strength of at least 80 kN/m, and a strain of at most 5% when subjected to a tensile load of 80 kN/m. Also here, the dimensions of the revetment block may in addition or alternatively also be defined in terms of a nominal diameter in the range of 30-60 cm, the nominal diameter is defined as the cube root of the volume of a block, i.e. nominal diameter = (volume block). In further embodiments of the fourth aspect of the invention, the sediment may be a sediment as defined and elucidated in relation to the first aspect of the invention; and/or the geo-textile may be a geo-textile as defined and elucidated in relation to the first aspect of the invention; and/or the intermediate layer may be an intermediate layer as defined and elucidated in relation to the first aspect of the invention; and/or the slope body may be a slope body as defined and elucidated in relation to the first aspect of the invention; and/or the revetment blocks may be revetment blocks as defined and elucidated in relation to the first and/or second aspect of the invention; and/or the step of placing the revetment may comprise placing the revetment blocks in an arrangement as defined and elucidated in relation to the first aspect of the invention; and/or the step of applying the intermediate layer comprising a first sub-step of applying a gravel layer onto the slope body, followed by a second sub-step of applying the geo-textile onto the gravel layer.
The invention will be explained further with reference to the drawings. In these drawings:
Figure 1 shows schematically, stepwise the process of constructing a wave/water- retarding slope according to the prior art, Fig. 1A showing a first step in the construction, Fig. 1B showing a second step in the construction, Fig. 1C showing a third step in the construction, Fig. 1D showing a fourth step in the construction, and Fig. 1A showing a fifth step in the construction.
Figure 2 shows schematically, stepwise the process of constructing a wave/water- retarding slope according to a first embodiment of the invention, Fig. 2A showing a first step a) in the construction, Fig. 2B showing a second step b) in the construction, and Fig. 2C showing a third step c) in the construction.
Figure 3 shows schematically, stepwise the process of constructing a wave/water- retarding slope according to a second embodiment of the invention, Fig.3A showing the initial situation, Fig. 3B showing a first step in the construction, Fig. 3C showing a second step in the construction, and Fig. 3D showing a third step in the construction.
Figure 4 shows schematically, stepwise the process of constructing a wave/water- retarding slope according to a third embodiment of the invention, Fig.4A showing a pre- existing situation, Fig. 4B showing a first step in the construction, Fig. 4C showing a second step in the construction, and Fig. 4D showing a third step in the construction.
Figure 5 shows schematically, stepwise the process of constructing a wave/water- retarding slope according to a fourth embodiment of the invention. This fourth embodiment is shown as a variant of the process of construction and embodiment shown in figure 4. This variant is however mutatis mutandis also applicable to the process of construction and associated embodiment shown in Figure 2 and Figure 3, respectively. The difference is that in figure 5, the third step of ‘applying the intermediate layer has two sub-steps and that the intermediate layer comprises a geo-textile and a gravel-layer below the geo-textile. Fig.5A is not shown, but is identical to Fig. 4A, and would show the first step in the construction. Fig.
SB is shown, is identical to figure 4B, and shows a second step in the construction. Fig. 5C-1 shows the first sub-step of the third step in the construction, which first sub-step is a step of applying a gravel layer, which takes place before applying the geo-textile. Fig. 5C-2 shows the second sub-step of the third step in the construction, which second sub-step is the step of applying the geo-textile onto the gravel layer -. Fig. 5D shows the fourth step in the construction.
Figure 6 shows a perspective view of a first stone-like revetment block which may be used in the wave/water-retarding slope according to the invention.
Figure 7 shows another perspective view of the same revetment block as in figure 6, showing in dashed lines a part of a further revetment block to illustrate how a revetment block of a higher row is supported on two revetment blocks of an adjacent lower row.
Figure 8 shows schematically a perspective view onto a wave/water-retarding slope according to the invention with a revetment of blocks as shown in figures 8 and 7.
Figure 9 shows a perspective view on the back side of the revetment of figure 8.
Figure 10 shows schematically the pattern of the contact surfaces of the revetment of figures 8 and 9.
Figure 11 shows a perspective side view of a second stone-like revetment block which may be used in the wave/water-retarding slope according to the invention.
Figure 12 shows a perspective back view of the same revetment block as in figure 10.
Figure 13 shows a perspective view on the back side of a revetment with the revetment blocks of figures 11-12.
Figure 14 shows schematically the pattern of the contact surfaces of the revetment of figure 13.
Figure 1 shows schematically, stepwise the process of constructing a wave/water-retarding slope according to the prior art.
Fig. 1A showing a first step in the construction, the first step being the step of providing a slope body. Fig. 1A shows in perspective and cross-section a slope body 1 of a land-backed dyke. The slope body 1 has a slope surface 2 on the waterside of the dike, a slanting face 3 on the landside of the dyke, and a crest face 4 on top of the dyke. The slope body comprises a sediment having a grain size of at most 2 mm, such as sand or clay.
Figs. 1B-1E all show the slope body of Fig. 1A only as a light grey-coloured cross-section. In addition to Fig. 1A, the Figs. 1B-1E schematically show the water level 6 at the waterside of the dyke.
Fig. 1B shows that, according to the prior art, in a second step, a geo-textile 5 is placed onto the slope surface 2. This geo-textile is shown as a relatively thick black line. The geo-textile has a land side face 7 facing the slope body, and has a water side face 8 facing in opposite direction, away from the slope body 1 to the water 6.
Figs. 1C-1D show that according to the prior art a so called filter layer 9, 10 is arranged on the water side face 8 of the geo-textile 5. Figure 1C shows applying — in a third step — a lower filter layer 9, shown in dark grey. This lower filter layer 9 is a layer of gravel. Figure 1D shows applying — in a fourth step — an upper filter layer 9, shown as black-rimmed white. This upper filter layer 10 is a layer of riprap.
Fig. 1E shows a fifth step in which a revetment 11 of stone-like revetment blocks is placed onto the upper filter layer 10, in which the revetment has an open structure configured for wave/water-retarding.
Figure 2 shows a first embodiment of the invention. Figure 2 shows schematically and stepwise the method — according to the fourth aspect of the invention - of constructing a wave/water-retarding slope according to the first aspect of the invention. Fig. 2A shows the first step a) of providing a slope body, Fig. 2B shows the second step b} of applying an intermediate layer, and Fig. 2C shows the third step c) of placing a revetment.
Fig. 2A and Fig. 2B are basically the same as Fig. 1A and Fig. 1B.
Fig. 2A shows in perspective and cross-section a slope body 1 of a land-backed dyke. The slope body 1 has a slope surface 2 on the waterside of the dike, a slanting face 3 on the landside of the dyke, and a crest face 4 on top of the dyke. The slope body is made of a sediment having a grain size of at most 2 mm, such as sand or clay. When building a wave/water-retarding slope structure according to the invention, a first step may be constructing a slope body, like in figure 1A. The slope body 1 may however also have been provided in other manner. It may for example also be provided by making a pre-existing, natural or artificial, dyke available or by reconstructing such a pre-existing dyke to have a slope surface at the waterside.
Figs. 2B-2C show the slope body 1 of Fig. 2A only as a light grey-coloured cross-section. In addition to Fig. 2A, the Figs. 2B-2C schematically show the water level 6 at the waterside of the dyke.
Fig. 2B shows that — in the second step of applying an intermediate layer — an intermediate layer is, according to the invention, placed directly onto the slope surface 2. As in the first embodiment, as shown in Fig. 2, the intermediate layer is only a geo-textile, the geo-textile 5 is placed directly onto the slope body 1, i.e. directly onto the sediment having a grain size of at most 2 mm. This geo-textile is shown as a relatively thick black line. The geo-textile serves to prevent migration of sediment of the slope body, which migration is also called washing out. The geo-textile has a land side face 7 facing the slope body, and has a water side face 8 facing in opposite direction, away from the slope body 1 to the water 6.
Fig. 2C shows that, in the first embodiment, a revetment 11 of stone-like revetment blocks is placed directly onto the geo-textile 5. The revetment 11 of revetment blocks has an open structure configured for wave/water-retarding. The revetment blocks of the revetment lie — according to the invention - directly on the water side face 8 of the geo-textile. Doing, so the prior art steps of providing a filter of two layers between the revetment and the geo-textile is thus dispensed with. The inventors found that — contrary to the general teaching in this field of wave/water-retarding structures — a geo-textile having a tensile strength of at least 80-100 kN/m with a strain of at most 3-5% at a tensile load of 80 kN/m does not require a filter layer of material of smaller size than the revetment blocks to be present between the revetment blocks and the geo-textile.
Figure 3 shows a second embodiment of the invention. Figure 3 shows schematically and stepwise the method — according to the fourth aspect of the invention - of constructing a wave/water-retarding slope according to the first aspect of the invention. Fig. 3A shows a starting point, Fig. 3B shows the first step a) of providing a slope body, Fig. 3C shows the second step b) of applying an intermediate layer, and Fig. 3D shows the third step c) of placing a revetment.
In this second embodiment, the starting point is a bank 12 as schematically shown in the cross-section of Fig. 3A, which extends along the water 6.
Similar as in the first embodiment of Fig. 2, a slope body 1 having a slope surface 2 is provided in a first step, shown in Fig. 3B. Like in the embodiment of Fig. 2, the slope body is constructed from a sediment having a grain size of at most 2 mm, such as sand or clay.
Similar as in Fig. 2B in relation to the first embodiment, Fig. 3C shows that — in a second step of applying an intermediate layer — an intermediate layer is, according to the invention, placed directly onto the slope surface 2. As in this second embodiment shown in Fig. 3, the intermediate layer is only a geo-textile, the geo-textile 5 is placed directly onto the slope body 1, i.e. directly onto the sediment having a grain size of at most 2 mm. Again, the geo-textile 5 is shown as a relatively thick black line. The geo-textile serves to prevent migration of sediment of the slope body, which migration is also called washing out. The geo-textile 5 has a land side face 7 facing the slope body, and has a water side face 8 facing in opposite direction, away from the slope body 1 to the water 6.
Similar as in Fig. 2C in relation to the first embodiment, Fig. 3D shows how, in the second embodiment, a revetment 11 is placed directly onto the geo-textile 5, the revetment having an open structure of revetment blocks. The revetment blocks of the revetment 11 lie directly on the water side face 8 of the geo-textile. Doing, so the prior art steps of providing a filter of two layers between the revetment and the geo-textile is dispensed with. The inventors found that — contrary to the general teaching in this field of wave/water-retarding structures — a geo- textile having a tensile strength of at least 80-100 kN/m with a strain of at most 3-5% at a tensile load of 80 KN/m does not really require a filter layer of material of smaller size than the blocks to be present between the revetment blocks and the geo-textile.
Figure 4 shows a third embodiment of the invention. Figure 4 shows schematically and stepwise the method — according to the fourth aspect of the invention - of constructing a wave/water-retarding slope according to the first aspect of the invention. Fig. 4A shows a starting point, Fig. 4B shows the first step a) of providing a slope body, Fig. 4C shows the second step b) of applying an intermediate layer, and Fig. 4D shows the third step c} of placing a revetment.
In this third embodiment, the starting point is an already existing land-backed dyke or dam 14 as schematically shown in the cross-section of Fig. 4A. This pre-existing dyke/dam 14 extends along the water 6. This pre-exiting dyke/dam 14 may for example be made of rock- material. Depending on circumstances, the pre-existing dyke/dam 14 may have been reconstructed or reshaped before the (first) step of Fig. 4B.
Similar as in the first embodiment of Fig. 2 and in the second embodiment of Fig. 3, a slope body 1 having a slope surface 2 is provided in a first step, shown in Fig. 4B. Like in the embodiments of Fig. 2 and 3, the slope body 1 is made from a sediment having a grain size of at most 2 mm, such as sand or clay.
Similar as in Figs. 2B and 3C in relation to the first respectively second embodiment, Fig. 4C shows that — in a second step of applying an intermediate layer — an intermediate layer is, according to the invention, placed directly onto the slope surface 2. As in this third embodiment shown in Fig. 4, the intermediate layer is only a geo-textile, the geo-textile 5 is placed directly onto the slope surface 2 of the slope body 1, i.e. directly onto the sediment having a grain size of at most 2 mm. Again, the geo-textile 5 is shown as a relatively thick black line. The geo-textile serves to prevent migration of sediment of the slope body, which migration is also called washing out. The geo-textile 5 has a land side face 7 facing the slope body, and has a water side face 8 facing in opposite direction, away from the slope body 1 to the water 6.
Similar as in Figs. 2C and 3D in relation to the first respectively second embodiment, Fig. 4D shows how, in the third embodiment, a revetment 11 of revetment blocks is placed directly onto the geo-textile 5. The revetment blocks of the revetment 11 lie directly on the water side face 8 of the geo-textile. Doing, so the prior art steps of providing a filter of two layers between the revetment and the geo-textile is dispensed with. The inventors found that — contrary to the general teaching in this field of wave/water-retarding structures — a geo-textile having a tensile strength of at least 80-100 kN/m with a strain of at most 3-5% at a tensile load of 80 kN/m does not really require a filter layer of material of smaller size than the blocks to be present between the revetment blocks and the geo-textile.
As a variant of the Fig. 4 embodiment, Fig. 5 shows a fourth embodiment of a wave/water- retarding slope according to the invention and its construction. In Fig. 5 the starting point is the same as in Fig. 4, i.e. an already existing dyke or dam 14. This starting point is not shown in Fig. 5. Fig. 5 starts therefore with Fig. 5B. The not-shown Fig. 5A is as such the same as
Fig. 4A.
The difference between the fig. 4 embodiment and the Fig. 5 embodiment is in the intermediate layer and its construction, i.e. the difference starts in fact as from Fig. 4C of the third embodiment.
In the fourth embodiment of Fig. 5, the intermediate layer is constituted by an assembly of a gravel layer 15 and a geo-textile 5. The gravel layer 15 is arranged on the inner side of the geo-textile 5, i.e. on the land side face 7 of the geo-textile which faces the slope body 1. This gravel layer 15 allows the slope surface to be steeper and assists in keeping the slope body more stable.
The gravel layer 15 at the inner side of the geo-textile results in the second step of applying the intermediate layer being subdivided into a first sub-step and a second sub-step. In the first sub-step shown in Fig. 5C-1, the gravel layer is applied on the slope body. The side of the gravel layer 15 facing the slope body may — in a further embodiment — be in direct contact with the sediment of the slope body having a grain size of at most 2 mm. In the second sub- step shown in Fig. 5C-2, the geo-textile is applied on the slope body. More particular, in the second sub-step the geo-textile 5 is placed onto the gravel layer, more specifically onto the side of the gravel layer facing away from the slope body 1, towards the waterside. The land side face 7 of the geo-textile (which faces the slope body) may — in a further embodiment — directly contact the (waterside of the) gravel layer.
Similar as in Figs. 2C, 3D, and 4D in relation to the first, second, and third embodiment, respectively, Fig. 5D shows how, in the fourth embodiment, a revetment 11 is placed directly onto the geo-textile 5, the revetment having an open structure of revetment blocks. The revetment blocks of the revetment 11 lie directly on the water side face 8 of the geo-textile.
Doing, so the prior art steps of providing a filter of two layers between the revetment and the geo-textile is dispensed with. The inventors found that — contrary to the general teaching in this field of wave/water-retarding structures — a geo-textile having a tensile strength of at least 80-100 kN/m with a strain of at most 3-5% at a tensile load of 80 kN/m does not really require a filter layer of material of smaller size than the blocks to be present between the revetment blocks and the geo-textile.
As will be clear, it is according to the invention, in a similar manner, also possible to construct the intermediate layer of the Fig. 2 and Fig. 3 embodiment as an assembly of a gravel layer 15 and a geo-textile 5.
Fig. 6 shows a stone-like revetment block 20 according to the earlier WO-2018/052292. For details about this revetment block 20 and its manner of laying these revetment blocks in rows on a slope, reference is made to this document W0O-2018/052292, which is in this respect incorporated by reference into this application.
The revetment block 20 is made of concrete and constituted by: — acentral part 26; — two wings 21, 22 projecting in mutually opposite directions from the central part 26 in horizontal direction, and — when arranged on a slope — parallel to the slope surface 2; — anose 23 projecting from the central part 26 transverse to the wings 21, 22, in a horizontal direction, and — when arranged on a slope — away from the slope surface 2; — atail 24 projecting from the central part 26 transverse to the wings 21, 22 in a horizontal direction opposite to the direction of projection of the nose 23, and — when arranged on a slope — towards the slope.
The revetment block 20 differs from the revetment block according to WO-2018/052292 in so far that the revetment block 20 is to say the little brother of the revetment block according to
WO-2018/052292. The revetment block according to WO-2018/052292 has a horizontal wingspan WS — measured from the free end of the wing 21 to the free end of the wing 22 - of about 180 cm, whilst this horizontal wingspan WS is in the revetment block 20 as shown in
Fig. 6 about 80 cm. For revetment blocks used in the present invention, the horizontal wingspan may vary in the range of about 55 cm to about 160 cm, such as in the range of about 55 cm to about 110 cm, in the range of about 130 cm to about 150 cm, or in the range of about 70 to about 150 cm.
Referring to Fig. 8, a slope surface 2 of a slope body 1 may be covered from the toe 13 to the crest 4 with multiple of rows R, Q of revetment blocks 20. As can be seen in Fig. 8, the revetment blocks 20 lie — according to the invention - directly on a geo-textile 5 which is provided on the slope surface 2. Although Fig. 8 shows a triangular patter of revetment blocks 20 provided on the slope surface, it will be clear that this is a schematic drawing and that in practise the length of the rows of revetment blocks 20 will in general correspond with the width of the slope, and that the height over which the slope is provided with rows of revetment blocks 20 may be the full height of the slope or less.
In Fig. 8 a revetment block 20a of the row Q has been shown in dark grey. This revetment block 20a is supported on two revetment blocks 20b and 20c of the row R just below row Q.
This manner of the lower revetment blocks 20b and 20c supporting the higher revetment block 20a, is further elucidated with reference to Fig. 7. In Fig. 7, the revetment block 20a is shown in solid lines, the revetment block 20b is partly shown in dashed lines, and the revetment block 20c is not shown for clarity reasons. As can be seen in Fig. 7, the right side of the nose 23 of the upper revetment block 21a is supported on the left wing 21 of the lower revetment block 20b. Similarly the left side of nose 23 of upper revetment block 21 will be supported on a right wing 22 of a left adjacent lower revetment block 20c (not shown in Fig. 7). Further, the right wing 22 of the upper revetment block 20a is supported on the left side of the tail 24 the lower revetment block 20b. Similarly the left wing 21 of the upper revetment block 20a will be supported on the right side of the tail 24 of the left adjacent lower revetment block 20c (not shown in Fig. 7). Further, the tails of the lower revetment blocks 20b and 20c (as well as the tails of the upper revetment block 20a) rest with their contact surfaces 25 (provided at the lower side of the free ends of the tails) on the geo textile 5 on the slope surface 2, resulting in that the bottom sides of the central parts 26 lie free from the geo-textile.
The revetment blocks 20 of the revetment thus contact the geo-textile 5 only with the contact surfaces 25, which are shown in dark grey in Fig. 9. Each part of the geo-textile 5 where a contact surface 25 of a revetment block 20 contacts the geo-textile is called a contact area.
The arrangement of revetment blocks 20 as is shown in Figs. 7 and 8, results in a pattern of contact areas corresponding to the pattern of contact surfaces shown in Fig. 10 (and Fig. 9, the dark grey).
Although Fig. 10 only shows the contact surfaces of three rows of revetment blocks, it can be seen from Fig. 10 that each contact surface has eight adjacent contact surfaces, two horizontally adjacent contact surfaces at a distance D1, two vertically adjacent contact surfaces at a distance D2, and four diagonally adjacent contact surfaces at a distance D3.
Note in this respect that ‘vertically’ and ‘diagonally’ in ‘vertically adjacent’ respectively ‘diagonally adjacent’ is not strictly vertical or diagonal respectively, as these directions are along the slope surface, which is a slanting surface.
In the embodiment of figures 6-10, the distance D1 may for example be about 69 cm, the distance D2 may for example be about 75 cm, and the distance D3 may for example be about 37 cm. The largest distance between adjacent contact areas is, in this example, thus at most about 75 cm. With such a largest distance between adjacent contact surfaces it is ensured that the geo-textile is kept sufficiently taught against the sediment at the land-side of the geo- textile, so that flapping, if not completely, is largely prevented. Defining a minimum distance between adjacent contact surfaces as a distance in horizontal direction or in a direction transverse to the horizontal and parallel to the slope surface (i.e. the above so called vertically adjacent), this minimum distance is in this example about 69 cm.
Further, in the embodiment of figures 6-10, about 5% to 10%, for example about 6.4%, of the geo-textile is contacted by all contact surfaces 25 of the revetment blocks 20 on the slope surface 2. The remaining 90% to 95% of the surface of the geo-textile is to say free from the revetment blocks 20, this remaining surface free from the revetment blocks is exposed to the openings of the open structure of the revetment, and is called the exposed .
Lab-experiments have shown that the configuration of revetment blocks 20 with the ‘littler brother’ dimensions, with the largest distance of about 75 cm between adjacent contact surfaces, and leaving about 90%-95% of the geo-textile free from the revetment blocks, is capable of reliably keeping the geotextile pressed against the slope body so that the slope body stays stable (and does not lose its stability due to the fine sediments becoming so to say fluidized by water entering the slope body). Further, the lab-experiments learned that this configuration also prevents the geo-textile from being damaged or rupturing by the revetment blocks.
In order to further improve the stability of the slope body, on the one hand, and the resistance of the geo-textile against being damaged or rupturing, on the other hand, the contact surfaces 25 at the tails 24 of the revetment blocks may — according to the second aspect of the invention - be enlarged to increase the total overlap of the geotextile with contact surface to a value in the range of 35% to 60%, such as in the range of 45% to 50% or in the range of 40% to 50%. Increasing the contact surface of a revetment block, like the one of Fig. 6 may, for example, be achieved by widening the free end of the tail to provide a larger contact surface.
An example of a revetment block 30 modified in this manner is shown in Figs. 11 and 12. The modified revetment block 30 has an enlarged tail 34 with an increased contact surface 35Fig. 13 shows a perspective view on the back side of a revetment of revetment blocks 30, and Fig. 14 shows the pattern of contact surfaces 35 of this revetment in plan view. As can be seen, adjacent contact surfaces 35 lie — viewed in diagonal direction — close to each other and enclose free areas 33 of geo-textile. With the revetment block 30 of figures 11-14, the contact surfaces 35 define so to speak lattices 31 and lattices 32, which are arranged crosswise to each other in a lattice like pattern with meshes 33 defining the free parts of the geo-textile which are not in contact with the revetment blocks.
In the embodiment of Figs 11-14, there is due to ‘adjacent contact surfaces lying — viewed in diagonal direction — close to each other’ effectively about no distance D3, which is in Fig. 10 clearly present. In a first exemplary embodiment of Figs. 11-14, the distance D1 may be about 40 cm, the distance D2 may be about 44,5 cm, the percentage of geo-textile contacted by the contact surfaces of the revetment blocks may be in the range of 45% to 50% (i.e. percentage of the geo-textile left free from contact with revetment blocks being in the range of 50 % to 55 %), and the wingspan WS of the revetment block may be about 82 cm.
These dimensions may however differ. According to a second exemplary embodiment of
Figs. 11-14, the distance D1 may be about 72 cm, the distance D2 may be about 79 cm, the percentage of geo-textile contacted by the contact surfaces of the revetment blocks may be in the range of 45% to 50% (i.e. percentage of the geo-textile left free from contact with revetment blocks being in the range of 50 % to 55 %), and the wingspan WS of the revetment block may be about 145 cm. Here wingspan is defined as the distance from the right end of the right wing to the left end of the left wing.
In addition to increasing the contact surface of the revetment block, the revetment block according to the second aspect of the invention also allows the revetment blocks being large sized — like is known from WO-2018/052292 — whilst keeping the distance between adjacent contact surfaces in the range of about 40 cm to about 90 cm, such as in the range of about 40 cm to about 80 cm.
Claims (35)
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| NL2034112A NL2034112B1 (en) | 2023-02-08 | 2023-02-08 | Wave/water-retarding slope |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| NL2034112A NL2034112B1 (en) | 2023-02-08 | 2023-02-08 | Wave/water-retarding slope |
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| Publication Number | Publication Date |
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| NL2034112B1 true NL2034112B1 (en) | 2024-08-29 |
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| NL2034112A NL2034112B1 (en) | 2023-02-08 | 2023-02-08 | Wave/water-retarding slope |
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE2433031A1 (en) * | 1974-07-10 | 1976-01-22 | Hinrich Koenig | Water permeable composite cover for canal embankments - has permeable plastics mat and layer of nonkeyed blocks |
| EP1464760A2 (en) * | 2003-03-27 | 2004-10-06 | Niklas-Simon Dipl.-Med. Graul | Earth wall with lawn cover, in particular dike |
| WO2018052292A1 (en) | 2016-09-14 | 2018-03-22 | Koninklijke Bam Groep N.V. | Cover element of concrete for a breakwater or jetty construction, as well as breakwater or jetty construction provided with a plurality of such elements |
| CN111962471A (en) * | 2020-08-24 | 2020-11-20 | 中交水利水电建设有限公司 | Construction method of artificial lake reclamation dam |
-
2023
- 2023-02-08 NL NL2034112A patent/NL2034112B1/en active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE2433031A1 (en) * | 1974-07-10 | 1976-01-22 | Hinrich Koenig | Water permeable composite cover for canal embankments - has permeable plastics mat and layer of nonkeyed blocks |
| EP1464760A2 (en) * | 2003-03-27 | 2004-10-06 | Niklas-Simon Dipl.-Med. Graul | Earth wall with lawn cover, in particular dike |
| WO2018052292A1 (en) | 2016-09-14 | 2018-03-22 | Koninklijke Bam Groep N.V. | Cover element of concrete for a breakwater or jetty construction, as well as breakwater or jetty construction provided with a plurality of such elements |
| CN111962471A (en) * | 2020-08-24 | 2020-11-20 | 中交水利水电建设有限公司 | Construction method of artificial lake reclamation dam |
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