EP3378993A1

EP3378993A1 - Protective construction for preventing erosion of a ground surface arranged adjacent to a body of water

Info

Publication number: EP3378993A1
Application number: EP18163812.3A
Authority: EP
Inventors: Carsten Aagerup
Original assignee: Fam AG Holding Aps
Current assignee: Fam AG Holding Aps
Priority date: 2017-03-23
Filing date: 2018-03-23
Publication date: 2018-09-26

Abstract

Protective construction suitable for preventing erosion of a sloping ground surface arranged adjacent to a body of water, said protective construction comprising a first sloping ground surface having a first acute angle to the horizontal, a first reinforcement covering made of organic material covering said first sloping ground surface and a first set of ground anchors for securing the first reinforcement covering to said first sloping ground surface. The protective construction further comprises: a second sloping ground surface being located above the first sloping ground surface and having a second acute angle to the horizontal which is greater than the first acute angle of the first sloping ground surface, a second reinforcement covering made of organic material and covering said second sloping ground surface, and a second set of ground anchors configured for securing the second reinforcement covering to said second sloping ground surface.

Description

The present invention relates to a protective construction suitable for preventing erosion of a sloping ground surface arranged adjacent to a body of water, said protective construction comprising a first sloping ground surface having a first acute angle to the horizontal, a first reinforcement covering made of organic material covering said first sloping ground surface and a first set of ground anchors for securing the first reinforcement covering to said first sloping ground surface.
Moreover the current invention relates to a method of establishing said protective covering.
The current specification also discloses a number of additional inventions which could be prosecuted in the future via divisional applications. It is to be noted that the invention disclosed in the claims as filed relates to a protective covering suitable for use along coastal areas. The other inventions as will be discussed later on in this specification are also suitable for use in coastal areas, but could also be used in other non-coastal applications.

Description of related art

Recent climate changes have caused raised water levels. In addition, the occurrence of severe weather conditions in the form of high winds and associated extreme tides have become more frequent. Therefore coastlines have, in some areas, become more exposed to erosion. The erosion removes sand and other materials from beaches, dunes, seawalls or cliffs on the backshore of the coastline. This causes the coastline to gradually move inland.
Areas close to the coastline have been attractive locations for housing developments. Oceanfront houses are now, in many areas, threatened by the sea as the coastline approaches the houses. Loss of houses into the sea due to coast erosion has become a reality, especially in areas with sand beaches and dunes, where e.g. a frequent wind direction causes erosion of the coast line.
In the past various means of preventing erosion or preserving the coastline have been introduced.
WO 2010/085075 A2 discloses a vegetation mat for protecting the bank of a river and slope including a fixing apparatus used in the same.
The vegetation mat comprises a plurality of layers which are from the innermost layer to the outermost layer: a first biodegradable net placed on the surface of the slope, a vegetation sheet with seeds of plants attached, a jute net made of coconut shells with a surface woven from jute into a grid and attached to the vegetation sheet, a coconut mat tightly formed by stacking coconut shells into a predetermined thickness, a second biodegradable net and a reinforcing wire in the form of a rope installed in the vertical or horizontal lengthwise direction of the slope.
The fixing apparatus comprises a main body constituted by a V-shaped blade having a centre with two through-holes, a U-shaped iron wire and a cylindrical striking device with a handle. The legs of the U-shaped iron wire extend through the through-holes past the top opening in the V-shaped blade. The striking device is arranged between the legs of the U-shaped iron wire.
The fixing apparatus is pushed through the vegetation mat until the handle is abutting the vegetation mat and thereby fixing said mat to the slope. The V-shaped blade will, when properly inserted, act as a barb because the legs of the V-shaped blade will tend to widen if the iron wire is being subjected to a pull force and thereby resisting the movement of the fixing apparatus out of the soil. However, the V-shaped blade will not provide much resistance against a push force.
However, as the V-shaped blade is pushed through the soil it will destroy the adherence of the soil. Thus, the soil will be less able to hold on to the fixing apparatus.
Moreover, if a stone or other hard object intersects the path of the V-shaped blade during insertion into the soul of the slope it may bend until it is flush against the cylindrical striking device. In this case the V-shaped blade will not provide the expected resistance against a pull force applied to the vegetation mat and the vegetation mat may become loose.
GB 2212 196 A , discloses a method of stabilising a slope or a side wall of an excavation, which method does not require heavy hammer action equipment, and does not incorporate a grouting operation, where a plurality of rigid anchors are screwed into the ground at angles to face the slope or the side wall of the excavation. Each ground anchor comprises a rod having at least over a part of its length nearer its leading end at least one helically extending fin, which cuts its way through the soil as the rod is rotated about its axis. The method is especially applicable to the soil nailing technique but it can also be employed in the reticulated micro-piling and dowling techniques. It is suitable for both permanent and temporary stabilisation of slopes and side walls of excavations, and where temporary stabilisation is required each ground anchor can be readily unscrewed from the ground and reused elsewhere. The anchors disclosed in GB 22102 196 A , may be useable in connection with the vegetation mat for protecting the bank of a river and slope disclosed in WO 2010/085075 A2 , however, the helical fin disclosed in GB 22102 196 A is defined as each ground anchor comprising a rod having at least over its part of its length nearest to its leading end, at least one helically extending fin, and the drawings do not disclose that the helical fin may have a larger extent than one turn. This might be sufficient when using the anchors in relative stable conditions, but using the anchors in combination with the vegetation mat for coastal protection where the vegetation mat is exposed to undulating movements due to the waves, combined with the sandy soil conditions at the coast, a higher torque resistance is required than the one obtainable from the anchors disclosed in GB 22102 196 A .
Applicant's own prior Danish application with application number PA201570344 is also referred to as a relevant prior art method. It is incorporated by reference in its entirety into the current specification.
Further the use of the vegetation mat disclosed in WO 2010/085075 A2 is not suited for protecting sea shores and dunes at coastlines, as the undulating waves flush away the sand at the lower edge of the mat, undermining it. The undermined areas of the mat will be vulnerable when exposed of the wave activity pull push forces, as the undermined areas of the mat is not maintained in position by the ground anchors, when the ground surface supposed to support the mat is flushed away.
Protecting the sea side of dunes and the shore in front of them against sea erosion has become very essential, but it is difficult to establish an effective protection against the waves impact pushing and pulling in the materials used for coastal protection.
Stormy weather combined with raised water level causes erosion of the dunes, where material is eroded from the dune foot, causing higher level material to dump downwardly. Arranging a protective covering for preventing the ground surface of the seaside of the dunes as disclosed in WO 2010/085075 A2 or applicant's Danish patent application number PA201570344 , would have some protecting effect, however, experience has shown that the material at the foot of dunes nevertheless becomes eroded where the protective covering ends, with the underlying material along the boundary / edge of the protecting cover is pulled into the sea due to the wave activity, this will cause damage to the protecting cover, and make large grooves in the foot of the dunes, and will result in erosion of the coast, but slower than if no protective covering were made.
An object of the present invention is therefore to provide an improved protective construction for preventing erosion of a coastline.

Summary of the invention

According to the present invention, this is achieved by a protection construction as defined by the characterizing portion of claim 1. In this way, a construction is provided where a first lower portion is used to absorb the energy of the waves and a second upper portion is provided to build up the bank to a certain height. With this two portion construction, a more effective coastal protection construction is provided than what is known in the art.
Additional beneficial features are disclosed in the dependent claims.
In one embodiment, the ground anchors of said first and second set of ground anchors could comprise an elongate anchor body with anchoring means for securing the ground anchors in the ground surface. In one embodiment, a first transition area could be arranged between the first and second sloping ground surfaces. In one case, the sloping ground surface could be located above the typical water level of the body of water.
The axial movement of the ground anchors due to the undulating forces acting on the reinforcement covering and transferred to the ground anchors is reduced by the invention. Thus, the ground anchors will resist the push forces from the water as the waves impact the reinforcement covering as well as the pull forces as the water retracts. Both have been found to be important as undulating axial movement of the ground anchors will cause erosion in the vicinity of the ground anchors including the anchoring means. Such erosion will gradually decrease the anchoring capabilities of the ground anchors. This is a problem that has not been realised in the prior art, but is alleviated with the present invention.
In certain embodiments, the protective construction could further comprise a transverse barrier arranged at the edge of the first reinforcement covering closest to the water, said transverse barrier being arranged as an at least partially buried vertical fence like element having a porous structure allowing water to seep down through the internal construction of the transverse barrier. Hereby is achieved that the undulating impact of the waves on the protective covering of organic material are reduced considerably, as the waves are 'broken' by the barrier, and thus the wave impact on the seaside edge of the protective covering is decreased. Barriers might also be located in higher levels of the ground surfaces to be protected by the protective covering of organic material for preventing erosion.
As the wind direction almost never is perpendicular to the coast, the undulating impact of the waves most frequently follows the wind direction, it might be preferable to reduce the oblique transverse directed impact from the waves, on the protective covering of organic material. This may be achieved by at least the seaside barrier comprises transverse extending barriers extending from the transverse barriers towards the higher levelled ground surface.
The presence of the transverse extending barriers extending from the transverse barriers towards the higher levelled ground surface will reduce the transversal impact of the waves on the reinforcement covering of organic material.
Without waiving the use of other suitable materials one possible option is that the barriers consists of upstanding bundles of willow rods. Bundles of willow rods have the excellent property, that they allow water to pass through, but break the undulating forces of the waves, while also retaining sand.
It should also be mentioned, that the barriers may be built from a combination of mutually different materials, to form the most efficient barrier adapted to local conditions.
In another embodiment, the transverse barrier may consist of fascines, held in position along the seaside edge by interspaced partly buried, upstanding posts, at least extending to the top level of the reinforcement covering.
In an embodiment of the invention the reinforcement covering further comprises a vegetation mat, wherein the vegetation mat is positioned on the ground surface and secured with the reinforcement covering.
The vegetation mat could be a mesh with barrier properties such that it prevents or at least inhibits sand and soil particles to move through the mat. Moreover, the vegetation mat provides a substrate for new vegetation, for example psammophylic (sand-loving) species of grass, such as marram grass (Ammophila arenaria) or lyme grass (Leymus arenarius). The vegetation will add to the barrier properties of the protective covering and assist in preventing erosion by also reducing wind speed across the surface and thereby trapping and holding sand. Furthermore, the vegetation will hide the reinforcement covering such that the ground surface appears natural.
The reinforcement covering ensures that the vegetation mat, which may be relatively fragile, is complete and held in place. Furthermore the reinforcement covering causes the point forces from the ground anchors to be distributed across a larger area of the vegetation mat, thus the forces do not exceed the yield strength of the vegetation mat. The mesh size of the reinforcement covering is selected in order to achieve the above objectives.
Where the ground surface is already covered in vegetation such as the above mentioned species the vegetation in combination with the reinforcement covering according to the invention provides the same advantages as described above.
The density and distribution of the ground anchors across the protective construction may vary according to the push/pull forces that the reinforcement covering is subjected to. For example the density of ground anchors may increase towards the lower end of the slope as water will impact the protective construction more frequently here.
The invention moreover enables reclaiming of land by adding at least one additional reinforcement covering spaced from the original reinforcement covering by a layer of substrate.
This process can be repeated as desired.
In one embodiment, the ground anchors comprise an elongated body and a helical anchoring element extending over more than half of the length of the elongate anchor body. In one embodiment the helical anchoring element has a diameter which is less than twice the diameter of the elongated anchor body.
In one embodiment, the upright elements could comprise bundles of willow rods. In one embodiment, the bundles of willow rods could be arranged in pads having more than 2 layers of willow rods.
In one embodiment the reinforcement covering could be thicker than 3cm, thicker than 4cm, thicker than 5cm, thicker than 7cm or thicker than 10cm. In one embodiment, the reinforcement covering could be composed of tree branches, for example evergreen branches which are laid out covering the sloping ground surface.
In one embodiment, the reinforcement covering comprises elongated rod like elements woven into mats. In one embodiment, the elongated rod like elements are willow rods. The reinforcement covering could also comprise additional layers, for example nets, mats, woven nets, coconut nets. In one embodiment, the reinforcement covering is arranged as elongated bundles of willow rods held together by wrapping an elongated holding element, for example a wire, around the bundles of willow rods. In one embodiment, the elongated bundles of willow rods are joined together with other adjacent elongated bundles of willow rods.
In one embodiment the reinforcement covering is arranged as mats which are woven together.
In one embodiment, the elongated holding elements could be metal tubes. In one embodiment, the elongated holding elements are metal wires arranged between adjacent ground anchors. In one embodiment, the elongated holding elements could be elongated bundles of willow rods held together by wrapping an elongated holding element, for example a wire, around the bundle.
It should be noted that the current specification discloses at least four different inventions. A first invention is defined in the claims. A second invention relates to a protective construction as mentioned in claim 1 and 2, but not limited to having two sloping surface. For example, a single sloping surface with a reinforcement covering which is thicker than 2cm. This provides for a more stable construction than thin reinforcement nets and allows sand/dirt to be absorbed in the reinforcement covering.
Another invention relates to a protective construction having transverse barrier elements as described herein. This feature could be combined in different embodiments as should be clear to the person skilled in the art based on this specification.
Another invention relates to the spring biased ground anchors as disclosed herein. In one embodiment, the ground anchor has at least two positions where in a first position, it is visibly clear that the anchor is engaged with the reinforcement covering and in another position it is visibly clear that the anchor is not as securely engaged as before.
It should be emphasized that the term "comprises/comprising/comprised of" when used in this specification is taken to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

Brief description of the drawings

In the following, the invention will be described in greater detail with reference to embodiments shown by the enclosed figures. It should be emphasized that the embodiments shown are used for example purposes only and should not be used to limit the scope of the invention.

Figure 1 schematically shows a cross section of a ground surface with a protective covering.
Figure 2a shows a first embodiment of a ground anchor.
Figure 2b shows the ground anchor of figure 2a with an extension means.
Figure 3 shows a cross section of a ground surface with a two layered protective covering.
Figure 4 shows a cross section of a ground surface with a protective covering comprising another embodiment of a suitable ground anchor.
Figure 5a and 5b show another embodiment of a ground anchor with an embodiment of attachment means for connecting the ground anchor to the reinforcement net.
Figure 6a shows an embodiment of a ground anchor with a spring biased hook shaped head in a first position.
Figure 6b shows the ground anchor of figure 6a where the hook shaped head is in a second position.
Figure 7a schematically shows a protective covering held in place with the ground anchors of figures 6a and 6b at a first time.
Figure 7b schematically shows the protective covering of figure 7a at a second time, later than the first time.
Figures 8a to 8f schematically show some steps during the process of applying one embodiment of the protective covering to a slope.
Figures 9 and 10 schematically show two embodiments of the protective covering when applied to a slope.
Figures 11a and 11c schematically illustrate the development of the protective covering over time.
Figures 12 and 13 schematically show two other embodiments of the protective covering.

Detailed description of the embodiments

Fig. 1 shows a cross section of a ground surface 3 with a protective covering 1. This example is known in the art and is only used to provide background info for the current invention.
In the figure is shown the protective covering 1 comprises a vegetation mat 5, a reinforcement net 7 and a plurality of ground anchors 9.
The reinforcement net 7 is positioned on top of the vegetation mat 5 for securing said vegetation mat 5 to the ground surface 3.
The ground anchors 9 extend through the combined vegetation mat 5 and reinforcement net 7 and are secured to the reinforcement net 7 by reinforcement net attachment means 10.
The ground surface 3 is located adjacent a body of water 2. In one typical example, the body of water could be an ocean. The water 2 is bounded by a beach 4. The beach is in this case sand. The ground surface comprises a sloping portion 6 which is the portion covered by the protective covering 1.
This example increases the stability of the slope significantly and provides a good and strong slope which over time fills with plants and grass and can regenerate itself. However, in the case of storms or high tides, the water 2 will rise and pound in against the bottom of the sloping portion 6. This will cause the bottom portion of the sloping portion to be damaged. Typically, the sand underneath the protective covering along the bottom portion of the sloping surface will erode. In many cases, this can cause the entire slope to collapse. Hence the solution shown in figure 1 is quite suitable for excavations and other constructions which are not exposed to the forces of waves.
Fig. 2a shows a first embodiment of a ground anchor 9 and fig. 2b shows the ground anchor of fig. 2a with an extension element 23.
The ground anchor 9 comprises an elongate anchor body 11 that provides strength and stiffness to the ground anchor 9 and an anchoring means 15.
The anchor body 11 can be made of steel, aluminium, composite or other high strength material. The anchor body 11 has a centreline 13 from end to end.
The anchoring means 15 of fig. 2a comprises a plate shaped member 17 that is attached to the anchor body 11. In the first embodiment the plate shaped member 17 is a helical flange. In this embodiment, the helical flange extends over more than 50% of the length of the elongated anchor body. Likewise, the diameter of the helical flange is less than twice the diameter of the helical flange.
In the inserted position of the ground anchor 9 of fig. 2a the anchoring angle, which is defined as the angle between the plate shaped member 17 and the centreline 13 in a plane parallel to the centreline 13, is 90° or within 80° to 100° depending on the stiffness of the plate shaped member 17.
Moreover the helical flange provides a pitch angle in relation to a plane normal to the centreline 13. Thus, in this embodiment the ground anchor 9 can be screwed into the ground surface 3 towards the inserted position of the ground anchor 9.
The ground anchor 9 comprises a reinforcement net attachment means 10 for connecting the ground anchor to the reinforcement net 7. The axial position of the reinforcement net attachment means 10 can be adjusted through a threaded connection 21 to the anchor body 11.
In figure 2b the ground anchor of figure 2a is depicted with an extension element 23. The extension element 23 comprises an elongate extension body 25 that is coaxially attached to the anchor body 11 of the ground anchor 9 with co-operating attachment means. The extension body 25 is threaded such that a reinforcement net attachment means 10 positioned on the extension body 25 can be adjusted axially.
Fig. 3 shows a cross section of a ground surface 3 with the protective covering 1' in a second embodiment.
In the second embodiment a layer of substrate 27, for example a layer of sand, an optional additional vegetation mat 5' and an additional reinforcement net 7' are added on top of the first embodiment of the protective covering 1.
The additional vegetation mat 5' and the additional reinforcement net 7' is held in place by a extension elements 23 that are coaxially connected to an anchor body 9 as shown in fig. 2b.
Fig. 4 shows a cross section of a ground surface 3 with the protective covering 1 and the ground anchors 9', 9", 9"' in an alternative embodiment.
The ground anchors 9', 9", 9'" each comprises two plate shaped members 17. The plate shaped members 17 are attached to the anchor body 11 through a deployment mechanism 31. The deployment mechanism 31 comprises a rod 33. The rod 33 is operably connected to the two plate shaped members 17 for deploying the plate shaped members 17.
The initial position of the plate shaped members 17 is a fully retracted position as can be seen on the anchor means referenced 9'. With the plate shaped members 17 in this position the anchor means 9' is inserted in the ground surface 3 and moved to a fully inserted position.
With the anchor means 9' in its fully inserted position the rod 33 is operated to move the plate shaped members 17 towards a fully deployed position.
The rod 33 of the anchor means referenced 9" is further operated so that the plate shaped members 17 is in an intermediate position with an anchoring angle of 45°.
The rod 33 has been operated further in the anchor means referenced 9"'. The plate shaped members 17 are further deployed with an anchoring angle of approximately 100°.
The rod 33 provides clear indication above the ground surface 3 as to the position of the plate shaped members 17 below the ground surface 3.
It is thereby possible to assess if the anticipated anchoring angle has been achieved by reading the position of the rod 33. Should the deployment of the anchoring means 11 be blocked for example by a stone or a rock before the desired anchoring angle is reached this would be immediately evident by the position of the rod 33.
Figure 5a shows a ground anchor 9 with a second embodiment of the attachment means 10 for connecting the ground anchor 9 to the reinforcement net 7. The attachment means 10 comprises a hook that engages with the reinforcement net. In the embodiment shown the ground anchor 9 is threaded. The attachment means 10 is secured and tightened with a nut.
The ground anchor 9 can be installed before the attachment means 10 is installed.
Figure 5b shows a third embodiment of the attachment means 10 for connecting the ground anchor 9 to the reinforcement net 7. The attachment means 10 is a clip that attaches to the reinforcement net 7 and the ground anchor. In one embodiment, it could be imagined that the reinforcement net holding the vegetation mat was comprised of metal tubes with clips 10 as shown in figure 5b at spaced apart locations. The attachment means 10 of figure 5a could then engage with the attachment means 10 of figure 5b.
Figures 6a and 6b show an example embodiment of another type of ground anchor 30 in two different positions. This embodiment of a ground anchor has a spring biased attachment portion 32 which can maintain a force which presses the reinforcement covering towards the ground surface under the reinforcement covering even in cases where the ground surface under the reinforcement covering should be washed away over time.
The ground anchor comprises an elongated body portion 34 and a helical flange 36 arranged along the elongated body portion. This allows the ground anchor to be screwed into the ground. A top portion 38 of the elongated body portion is formed as a nut which can be rotated with a tool (not shown). A stopper element 40 is fastened to the elongated body portion. A spring 42 is arranged between the stopper element and an attachment member 44. the attachment member is displaceably arranged to slide up and down on the elongated body portion. Due to the arrangement of the spring, the attachment member is forced downwardly.
As the ground anchor is screwed into the ground 46a, the attachment member will engage with the reinforcement covering 48 (in this schematic representation shown as an elongated tubular element). As the ground anchor is screwed further and further into the ground, the spring will be compressed and the attachment member 44 presses downwardly on the reinforcement covering. This is shown in figure 6a. In the case where the ground surface 46a under the reinforcement covering is removed 46b, for example if the sand is washed away by water action underneath the reinforcement covering, the attachment member 44 will be slowly displaced downwardly while constantly maintaining a pressure on the reinforcement net.
This type of spring biased ground anchor has great value in coastal areas where the reinforcement covering will be exposed to pulsating forces due to waves. If the reinforcement covering becomes loose, then pulsating forces will quickly break down the covering. But with the current spring biased mechanism, the reinforcement covering will not be allowed to freely move back and forth and will be held against the ground surface, thereby reducing the risk of damage to the covering.
Another advantage of the currently described ground anchor concept is that when the ground anchor is firmly screwed into the ground, the top portion 38 of the elongated body portion of the ground anchor is screwed into the displaceable attachment member and is hidden from view. As the ground surface lowers due to removal of sand for example, or in the case where the ground anchor has not been engaged properly in the soil and slowly withdraws. the attachment member will slowly displace downwardly with respect to the top portion of the elongated body portion causing it to be more and more exposed. This can be seen in figure 6b. By inspecting the ground anchors over time, it can easily be seen in which areas the ground surface is being washed away under the reinforcement covering. The ground anchors which are located in areas where the ground surface is sinking, can then be screwed further into the ground. Or in certain cases, it could be relevant to repair certain areas with more sand/substrate and additional reinforcement coverings. By making the top portion 38 of the elongated body portion 34 a bright colour, it will be possible to see which areas of a slope are sinking just by looking at the slope from a distance.
This is shown schematically in figures 7a and 7b which show the same reinforcement covering 50 being held in place by three ground anchors 52a,52b,52c of the kind shown in figures 6a and 6b. In figure 7a, the ground surface 54 is shown by a thick line 54. Over time, the ground surface is removed so that the ground surface is located at the dotted line 56. In figure 7b is shown the position of ground anchors when the ground surface has been removed to the dotted line in figure 7a. As can be seen, the ground anchor 52a is still properly engaged and the top portion of the elongated body portion is still hidden inside the anchoring portion. However, for the anchor 52c, the top portion has been completely revealed and can be seen from a distance.
Figures 8a-8f schematically illustrate one embodiment of how the protective construction according to the invention could be established and built up. In figure 8a, a sloping ground surface located adjacent to a body of water (not shown, but located to the left of the figures) is shown. The ground surface comprises a beach portion 60 and a bank portion 62. The beach portion is sand and the bank is a mixture of sand and dirt. Over time, the bank will be eroded by water action at its base and the bank will slowly erode. It is desired to re-establish the bank so that it does not erode further.
In a first step, as shown in figure 8b, sand 64 is filled into the area between the beach portion and the bank portion. A barrier element 66 in the form of vertically arranged willow rod pads is arranged at the water facing side of the new sand 64 portion. The new sand is formed to have two sloping portions, a first portion 68 defining a first sloping ground surface 70 and a second portion 72 defining a second sloping ground surface 74. The first sloping ground surface has an acute angle A to the horizontal which is less than the acute angle B to the horizontal of the second sloping ground surface. Between the first and second sloping ground surfaces there is a transition area 76.
On top of the new sand portion 64 is laid a net or carpet like covering 78 which is of organic material. One example of this could be a coconut fibre woven mat. The purpose of this first covering 78 is to hold onto the sand. The first covering should allow plants and plant roots to grow through the covering.
The first covering 78 could be a single piece of woven fabric, or it could comprise multiple sheets/portions of fabric/net/etc. It depends on what is available and what the size of the area that needs to be covered is. In certain embodiments, it might be desired to eliminate this first covering to reduce costs or complexity.
As shown in figure 8d, a number of willow rod mats 80 are laid out on top of the new sand portion 64. The willow rod mats 80 are formed as bundles of willow rods where the longitudinal extension of the willow rods would be into the page in this figure. The dimensions of the pads could be for example 100cm wide, 400cm long and 20cm high. This is just one example of a dimension. Other dimensions would also be possible. For example, the pads could be bundles being circular in cross section and extending many meters long. In this example, the pads are laid out adjacent to each other without any overlap. There could even be small gaps between the pads. However in other embodiments, it could be desired to have an overlap between adjacent pads. The pads could be laid out in a staggered pattern (as shown in figure 9), or they could be laid out in a more rectilinear pattern (not shown).
Once the pads are laid down, ground anchors 82 are inserted into the ground to hold the pads in place. The ground anchors could be of the kind shown in the previous figures. In this embodiment, an elongated holding element 84 is used to hold the pads in place. A ground anchor 82 engages with the elongated holding elements 84 to hold the pads in place. In this embodiment, the elongated holding elements extend to engage with two pads and one ground anchor, however, in other embodiments, longer elongated holding elements could be provided which engage with multiple pads and multiple ground anchors.
As can be seen from figure 8e, in different sections of the protective construction, different densities of ground anchors are used. Additional ground anchors can be added in areas where there are higher forces, for example at the lower end of the protective construction.
Once the ground anchors are in place, plants 86 can be planted in the protective construction in between pads or even into the pads themselves. Over time, the plants will grow roots which engage directly with the pads and the sand. The plants will grow over time and a strong root network will be established which gives good strength to the new sloping ground surface. Once the ground surface is strong enough, the ground anchors 82 and the elongated holding element 84 can easily be removed without causing very much damage to the plants and root network. Once the elongated holding elements and ground anchors are removed, the slope is left completely natural without any metal or cement or other hard and unwanted constructions.
Figure 9 shows a schematic representation in perspective of a protective construction. Figure 10 shows another embodiment where the elongated holding elements are longer and there are more ground anchors used. These two embodiments should just be used as very schematic examples showing some different possibilities.
Figures 11a to 11c show a cross section through a portion of the new construction over time. In figure 11a, the pads 80 have just been placed on the surface of the sand and the ground anchors 82 has been inserted into the ground and the elongated holding member 84 is holding the pads in place. As can be seen, the pads are formed of willow rods packaged into a pad. Plants 86 are planted in the ground between the pads.
Over time, sand is collected in the pads and between the pads so that the pads get completely covered and hidden. The pads slowly start to rot providing nutrients for plants which grow into the pads. This is shown in figure 11b. As the plants grow more and more, larger and longer roots are generated. Over time the ground anchors and the elongated holding elements can be removed, leaving only plants, sand and willow pads.
Figure 12 shows another embodiment, where a number of vertically arranged willow pads 88 with vertically arranged willow rods are arranged parallel to the shore and parallel to the first transverse barrier 66. When water flows up the lower portion of the sloping surface due to a wave, the water in the wave will be able to run down the vertically arranged willow pads and energy will be removed. Furthermore, instead of rushing back down the sloping surface and carrying sand away, the water will drain into the sloping ground surface, thereby reducing the amount of sand being removed. Figure 13 shows a similar embodiment with a number of vertically arranged willow pads offset from each other. In this case instead of having two sloping ground surfaces, only a single sloping ground surface is provided.
It is to be noted that the figures and the above description have shown the example embodiments in a simple and schematic manner. The internal mechanical details have not been shown since the person skilled in the art should be familiar with these details and they would just unnecessarily complicate this description.

Claims

Protective construction suitable for preventing erosion of a sloping ground surface arranged adjacent to a body of water, said protective construction comprising a first sloping ground surface having a first acute angle to the horizontal, a first reinforcement covering made of organic material covering said first sloping ground surface and a first set of ground anchors for securing the first reinforcement covering to said first sloping ground surface characterized in that the protective construction further comprises:
a. a second sloping ground surface being located above the first sloping ground surface and having a second acute angle to the horizontal which is greater than the first acute angle of the first sloping ground surface,

b. a second reinforcement covering made of organic material and covering said second sloping ground surface, and

c. a second set of ground anchors configured for securing the second reinforcement covering to said second sloping ground surface.
Protective construction according to claim 1, characterized in that first and/or second reinforcement covering is thicker than 2cm.
Protective construction according to claim 1 or 2, characterized in that the first and/or second reinforcement covering is comprised of elongated rod like elements.
Protective construction according to claim 3, characterized in that the first and/or second reinforcement covering comprises multiple layers of elongated rod-like elements.
Protective construction according to any one of claims 1-4, characterized in that the protective construction further comprises a plurality of elongated holding elements which are arranged above the first and/or second reinforcement covering(s) and which are held in place by the elongated ground anchors to thereby hold the first and/or second reinforcement covering(s) in place.
Protective construction according to any one of claims 1-5, characterized in that the protective construction further comprises a transverse barrier arranged at the edge of the first reinforcement covering closest to the water, said transverse barrier being arranged as an at least partially buried vertical fence like element having a porous structure allowing water to seep down through the internal construction of the transverse barrier.
Protective construction according to claim 6, characterized in that the transverse barrier comprises a plurality of individual and at least partially buried elongated upright elements, the adjacent sides of which are in abutment with each other.
Protective construction according to any one of the claims 6-7, characterized in that the at least partially buried elongated upright elements comprise a plurality of vertically arranged elongated rod like elements.
Protective construction according to any of claims 6 to 8, characterized in that the protective construction comprises more than one transverse barrier running along the edge of the reinforcement covering, said more than one transverse barriers being arranged offset from each other in a direction perpendicular to the extension of the transverse barrier.
Protective construction according to any one claims 1 to 9, characterized in that the ground anchors comprise a spring like biasing mechanism which biases the first and/or second reinforcement covering towards the first and/or second sloping ground surface respectively.
Protective covering according to claim 10, characterized in that spring like biasing mechanism of the ground anchors has at least two positions where in a first position, it is visibly clear that the anchor is engaged with the reinforcement covering and in another position it is visibly clear that the anchor is not as securely engaged as before.
Method of establishing a protective construction for preventing erosion of a sloping ground surface arranged adjacent to a body of water, wherein the method comprises the following steps:
a. preparing a first sloping ground surface having a first acute angle to the horizontal,

b. preparing a second sloping ground surface farther away from the water than the first sloping ground surface and having a second acute angle to the horizontal which is greater than the first acute angle,

c. placing a first reinforcement covering made of an organic material over said first sloping ground surface,

d. placing a second reinforcement covering made of organic material over said second sloping ground surface,

e. providing a plurality of ground anchors,

f. securing the first reinforcement covering to the first sloping ground surface by inserting a portion of said plurality of ground anchors into the first sloping ground surface, and

g. securing the second reinforcement covering to the second sloping ground surface by inserting a portion of said plurality of ground anchors into the second sloping ground surface.
Method of establishing a protective construction for preventing erosion of a sloping ground surface arranged adjacent to a body of water, wherein the method comprises the following steps:
a. preparing a first sloping ground surface having a first acute angle to the horizontal,

b. placing a first reinforcement covering made of an organic material over said first sloping ground surface,

c. placing a transverse barrier at the edge of the first reinforcement covering closest to the water, said transverse barrier being arranged as an at least partially buried vertical fence like element having a porous structure allowing water to seep down through the internal construction of the transverse barrier,

d. providing a plurality of ground anchors,

e. securing the first reinforcement covering to the first sloping ground surface by inserting a portion of said plurality of ground anchors into the first sloping ground surface.
Method according to claim 13, characterized in that the transverse barrier comprises a plurality of individual elongated upright elements, the adjacent sides of which are in abutment with each other.