Items for shoreline protection and method for making

Abstract

A seawall module for coastline protection comprising an outer rigid skin encasing an internal reinforcing rib structure and a filler material; the invention further includes a method for making said seawall module, the method comprising making an outer rigid skin with a lightweight material, and filling the skin with a filler material; other aspects of the invention include a seawall system comprising a plurality of seawall modules, a block for dissipating waves energy having a novel hybrid structure with a skin-filling composition and / or a novel shape, a method for making said block and a seawall or breakwater infrastructure comprising a plurality of seawall modules and blocks.

Description

[0001] Items for shoreline protection and method for making.

[0002] DESCRIPTION

[0003] Field of application

[0004] The present invention is in the technical field of shoreline protecting barriers. The invention concerns seawalls and armour blocks aimed to protect shorelines from waves action and sea level increase. The invention relates also to methods for making said seawalls and blocks.

[0005] Prior art

[0006] Coastal defence infrastructures are used to protect shorelines from severe wave action during adverse weather events, particularly in populated coastal areas. Because of the current climate change, the frequency of occurrence of such adverse weather events is increasing, as well as their strength. A further effect of climate change is the increase in sea level; according to estimations based on greenhouse gas emissions, an expected range of sea level increase goes from 0.8 to 1 .5 meters in the century to come.

[0007] A significant portion of the coastline needs additional protection systems beyond those that are currently employed. More than thirty major cities in the world with a population up to 40 million are included in high-risk areas for submergence with a projected sea level rise of 1.5 meters in the next century. Seawalls and armour blocks are effective means to provide such protection.

[0008] Coastal defence infrastructures include seawalls and armour blocks. A seawall can be made as a rubble mound dyke or using caissons. It is basically a barrier of desired length along the coast, allowing to maintain different sea levels between the front and back. The blocks are designed essentially to protect the filter layer of a rubble mound dyke from wave erosion, dissipate wave energy, and prevent wave overtopping. They may be used alone in breakwater rubble mounds to protect the coastline from storm surges or in combination with a seawall to also protect from sea level rise.

[0009] A seawall of the caisson type is typically made from seawall modules. In the prior art, a seawall module is essentially made of a concrete caisson. The modules may be placed on the filter layer of a submerged rubble mound dyke covered with armour blocks.

[0010] Armour blocks for shoreline protection are made of unreinforced concrete and are designed in different shapes. Since the beginning of using artificial concrete armours, blocks innovation mainly concerned the development of new and more complex shapes to increase performance. Examples of such shapes are the tetrapod, developed in 1950s but still in use, and the Xbloc™ disclosed in detail in EP 1540087.

[0011] Concrete is the predominant material for seawalls and armour blocks for shoreline protection, due to the high density and relatively low cost. Use of concrete leads to the required significant weight of such infrastructures, for example current seawall modules and blocks are typically up to 15’000 and 50 tons / each, respectively.

[0012] However, the considerable weight leads to significant cost and carbon footprint for transporting and installing. Usually, the site of production of the seawall modules and blocks does not coincide with the site of installation, so that transportation has a significant impact in terms of cost and emissions. Another drawback is that production is slow, so significant lead time and temporary large- scale storage are needed. The production of blocks or seawall modules of different shapes is also expensive, requiring different moulds for concrete. Furthermore, the service life of blocks is not completely satisfactory because low- cost concrete of common use suffers from erosion by seawater and waves; special mixtures of concrete for operation in seawater are available, but their cost is higher. Summary of the invention

[0013] The invention aims to solve the above drawbacks. The invention aims to provide novel structures for shoreline protection that are easier and less expensive to manufacture, with increased service life. The invention in particular aims to increase the construction speed, reduce the costs, and reduce the environmental impacts of on-site transportation and installation of large and heavy seawall modules and blocks.

[0014] An aspect of the invention is a seawall module according to claim 1 . The seawall module comprises an outer rigid skin, an internal reinforcing structure preferably including a plurality of ribs, and a filler material. The internal reinforcing rib structure and the filler material are encased by the skin resulting in a hybrid item.

[0015] The invention further relates to a seawall system including a plurality of seawall modules, and to a method for making said seawall module.

[0016] Further aspects of the invention include, in accordance with the claims: an armour block for shoreline protection and a novel shape of said block; a method for producing said block; a method for making a seawall or breakwater infrastructure; a mould for producing a block for shoreline protection, designed as a rigid skin.

[0017] An advantageous feature of the invention is the hybrid structure of the seawall modules and blocks. The rigid skin can be made of a lightweight high- performance material, such as fibre-polymer composite, providing optimal resistance in seawater; the filler material, such as dredged soil for seawall modules and unreinforced concrete for blocks, gives a suitable weight to the seawall modules and blocks. A further and noticeable advantage of this hybrid concept is that the lightweight rigid skin can be filled on site, thus greatly reducing cost and time for construction, transportation and installation. Description of the invention

[0018] First embodiment: seawall

[0019] In a preferred embodiment of the seawall module of the invention, at least the side surfaces and a top surface of the skin are made of fibre-polymer composite, said composite preferably including any of: glass fibres, basalt fibres, carbon fibres, vinylester, epoxy resin, structural foam.

[0020] The filler material is a solid having a density higher than the density of the seawater, said filler material being preferably soil.

[0021] In an embodiment, the skin includes a bottom surface preferably made of reinforced concrete. Said bottom surface preferably includes two edge beams that protect the side surfaces during transportation and installation of the module. The reinforced concrete includes concrete rebars preferably made of fibre- polymer composite.

[0022] The internal reinforcing rib structure may include any of: horizontal load-bearing members connecting opposite side surfaces of the skin; vertical members connecting top / bottom surfaces of the skin; diagonal members which diagonally connect different surfaces of the skin, or a combination of them.

[0023] Said internal reinforcing rib structure preferably includes a plurality of reinforcing assemblies, each assembly including a combination of horizontal, vertical and diagonal load-bearing members. Said load-bearing members preferably include compression members, denominated struts, and tension members, denominated tendons. The struts may be arranged to transmit compression and bending stress between different parts of the reinforcing rib structure or different parts of the skin. Said compression or bending stress may be originated by the dynamic pressure of the water transmitted to the structure, or by external loads such as vehicles passing onto the structure. The tendons may be arranged to transmit tension stress between different parts of the skin. Said tension stress may be originated by the resultant of the soil and static water pressure transmitted to the structure. The-internal reinforcing rib structure may also include at least one panel having a composite sandwich structure. Said panel may have a suitable design to transmit internal forces. Said panel preferably includes a peripheral frame or contour corresponding to upper, lower and lateral sides of the module, and one or more transverse parts arranged to transmit compression or tension stress within the panel. The panel is preferably configured with lightening windows in unstressed regions, to reduce the use of material.

[0024] In a particularly preferred embodiment, the internal reinforcing rib structure comprises: a set of struts made of a composite material including diagonal struts, preferably four; vertical struts, preferably two; one or more horizontal struts, preferably one; and horizontal tendons, preferably four, said tendons being made of a composite material and having preferably strap anchors that connect them with the lateral skins.

[0025] The seawall module has preferably one or more of the following dimensions: a height between 5 and 20 metres, a length between 15 and 25 metres, a width between 4 and 15 metres, and a rib spacing between 2.5 and 3 meters. Preferably, the seawall module has a shape with a rectangular cross-section. However, the shape can be varied to adapt to local conditions, e.g. by enlarging the base to better distribute stresses or curving the sea-sided skin to reduce wave overtopping.

[0026] The seawall module is usually designed with a height suitable for an expected sea level rise. In an embodiment of the invention, height extender modules are provided, which can be placed on top of the caisson module to increase the overall height of the caisson module. The use of such extenders may be appropriate if the rise of the sea level during the service life of the seawall is greater than expected. In a preferred embodiment, said extender is an L-shaped member. Depending on how much the observed sea level rises, the L-shaped extender may have a leg that rests on the ground so to discharge a part of the loads directly on the ground without excessively stress the internal reinforcing rib structure of the seawall module. The extender modules can also be used to increase the height of existing concrete caisson seawalls.

[0027] The extender preferably includes an internal truss structure for transmission of stress. The extender is coupled with the module by means of nodes of the truss structure of said extender corresponding to nodes of the internal reinforcing ribs of the module so to ensure load transmission through the seawall module down into the ground, or by means of a concrete filling.

[0028] Another aspect of the invention is a seawall system including a plurality of seawall modules connected with each other preferably by means of joints that ensure watertightness and allow horizontal and vertical tolerances of the module position to be compensated for. Said joints are preferably made of concrete.

[0029] A method for making the seawall module described above comprises the steps of: a) making at least part of the outer skin, preferably the lateral and top surfaces of said skin, with a lightweight skin material, assembling the lateral and top surfaces of the skin on the bottom skin made of reinforced concrete, and providing the internal reinforcing rib structure preferably made of the lightweight skin material which preferably includes a fibre-composite material, more preferably any of: glass fibres, basalt fibres, carbon fibres, vinylester, epoxy resin, structural foam; b) filling the outer skin with a filler material, preferably soil or sand.

[0030] In step a) pultrusion or vacuum infusion are preferably used to manufacture the fibre-polymer composite skins and ribs. Pultrusion is a continuous process for manufacturing composites materials with constant cross-section. Vacuum infusion is used to manufacture sandwich panels composed of composite face sheets and a structural foam core. Specifically, the skin is preferably assembled from pultruded panels or produced by vacuum infusion. The struts are preferably pultruded. The tendons with strap anchors are preferably made by filament winding. Tendons without strap anchors are also possible, however, they may be pultruded.

[0031] Concerning the skin, pultruded panels are multicellular panels which are adhesively bonded together to form the entire skin plate. Vacuum infusion is used in the case of sandwich panels, which consist of two outer composite face sheets and a homogeneous core material, e.g. a PVC foam. Both pultrusion or vacuum infusion may be used for the skin.

[0032] In a preferred embodiment, the method for producing the seawall module includes deploying the structure (reinforced skin) obtained at step a) underwater in the installation site and performing step b) by filling the skin with water during on-site deployment, and water is then replaced by the filler material.

[0033] According to an interesting embodiment of the invention, the formation of the item is completed on site, so that only the lightweight empty module must be transported and positioned, reducing transportation and installation costs and carbon footprints.

[0034] Second embodiment: armour block

[0035] The invention further relates to an armour block for coastal defence. Aspects of the invention include: a block with a hybrid structure; a method for making said hybrid block; a novel shape of a block which is applicable to both hybrid blocks and conventional concrete blocks. A block is an element which is usually interlocked with other similar elements to protect filter layers from wave erosion, dissipate wave energy, and prevent wave overtopping.

[0036] The hybrid structure of the block comprises a rigid skin made of a first material, the skin being filled with a second material. The first material preferably is a fibre- polymer composite, said composite preferably including any of: glass fibres, basalt fibres, carbon fibres, vinylester, epoxy resin. The second material is preferably unreinforced concrete.

[0037] The inventive shape of a block, in a broad aspect, comprises: a first base face and a second base face opposite along a main axis of the block; the first face having a first contour and the second face having a second contour, said first contour extending at least in part along a first ellipse and second contour extending at least in part along a second ellipse; the first ellipse is rotated relative to the second ellipse, preferably of 90°; the block comprises a side surface connecting the first face and the second face.

[0038] Said first face may extend on a plane perpendicular to the main axis of the block or on a plane forming a given angle with respect to a plain perpendicular to the main axis, said angle being preferably less than 45°.

[0039] According to variants, the block may have features such as protrusions and / or recesses on the base faces and / or on the side surface, leading to more complex shapes with increased interlocking capacity to protect filter layers, increased dissipation of the wave energy, and reduced wave overtopping. Different shapes may be adapted for single-layer or multi-layer positioning.

[0040] The novel shape of the invention can be applied advantageously to blocks with a hybrid composition, as mentioned above, and is also applicable to blocks with a conventional composition.

[0041] A method for making the hybrid block comprises the steps of: a) making an outer rigid skin with a lightweight material; b) filling the skin with a filler material, obtaining the block which includes the filler material, preferably unreinforced concrete, encased by the skin.

[0042] An interesting embodiment of the invention provides that the rigid skin is filled on site to facilitate handling and reduce transportation costs. According to this embodiment, the formation of the block is completed on site, so that only the lightweight rigid skin must be transported and positioned, thus reducing transportation and installation costs and related carbon footprints.

[0043] In a preferred embodiment, the step a) of the method comprises any of the following: a.1 ) fibre spray-up of the skin material onto a skin mould; a.2) resin transfer moulding (RTM) of the skin or of different parts of the skin to be subsequently bonded together preferably in an automated process; a.3) blow moulding of the skin material to produce the skin;

[0044] The fibre spray-up process can be performed by a robot. For example, a suitable sprayer of the skin material is fixed to an end effector of a robotic arm. The spray- up of the skin material may be performed from inside the mould or from outside the mould.

[0045] An embodiment of the inventive method includes: deploying the rigid skin at least partially underwater in the operative position, the skin being provisionally filled with seawater during deployment to facilitate handling underwater, and then introducing the filler material in the skin to expel and replace seawater. Another embodiment provides that the deployment of the skin is carried out above water in the installation site.

[0046] The filling of the skin leaves a small volume not filled with the filler material. The unfilled volume may favour population of living organisms.

[0047] An advantage of the invention is that the rigid skin can be produced in a variety of shapes, thus making the application more flexible.

[0048] Additional aspects of the invention

[0049] A further aspect of the invention is a method for making a breakwater or caisson seawall infrastructure lying on a rubble mound submerged in the sea, said infrastructure being adapted to dissipate wave energy and / or to maintain a sea level difference across that structure. The method comprises the step of installing a seawall system and providing a plurality of armour blocks wherein said seawall system and / or said blocks are the ones described above. A breakwater or seawall infrastructure has a first side facing the sea and a second side facing the coast. The blocks may be placed on the first side, or on both the first side and the second side of said infrastructure. The plurality of blocks may be installed in a multi-layer arrangement on the first side of the seawall or breakwater infrastructure so to reduce the forces acting on the seawall.

[0050] Still another aspect of the invention concerns a mould for producing a block for shoreline protection, the mould being designed as a rigid skin; the block filling being preferably made of concrete, and the mould being made of a fibre-polymer composite preferably including any of: glass fibres, basalt fibres, carbon fibres, vinylester, epoxy resin.

[0051] Advantages of the invention

[0052] The invention has a significant number of advantages.

[0053] Noticeably, the invention merges techniques from the remote fields of heavy concrete marine construction and slender, thin-walled composite construction, resulting in a novel approach to the manufacturing of items for shoreline protection.

[0054] The hybrid concept behind the structure of seawall modules and armour blocks of the invention has the considerable advantage that the production of the lightweight rigid skin can be centralized and skins of different shapes can be produced at competitive cost; the empty skins can be transported to the site of installation and manipulated with small lifting equipment; the heavier filling material can be introduced onsite or even underwater.

[0055] The invention therefore solves the problems of conventional seawall modules and armour blocks made of concrete, such as time-consuming production and expensive transportation and handling. The seawall module and block of the invention are also durable because only the composite material of the skin is directly in contact with the seawater; the filling is protected by the skin and can be made with inexpensive material.

[0056] The novel armour block shape of the invention, with respect to conventional block shapes, has advantages of: a high hydraulic stability thanks to its strong friction interlock; a high wave energy dissipation and reduced required concrete quantity thanks to the high porosity; high resistance to wave overtopping thanks to a low roughness coefficient.

[0057] A further advantage regards the novel mould. Said mould, being made of a fibrecomposite material, is lighter and therefore easier to transport and to handle with respect to conventional moulds that are typically made of steel.

[0058] Brief description of the figures

[0059] Fig. 1 illustrates a schematic view of the seawall according to an embodiment of the invention.

[0060] Fig. 2 is a cross-section view of a seawall with a rib composed of a strut-tendon system according to an embodiment of the invention.

[0061] Fig. 3 is a cross-section view of a seawall with the bottom skin conceived as a slab system for the transfer of the vertical pressure of the soil and / or live load on crown, according to an embodiment of the invention.

[0062] Fig. 4 is a cross-section view of a seawall with a tendon system to balance the static pressure on the lateral skins, according to an embodiment of the invention.

[0063] Fig. 5 is a cross-section view of a seawall with a strut system to transfer the dynamic wave pressure, according to an embodiment of the invention.

[0064] Fig. 6 is a cross-section view of a seawall with a strut-tendon system for live load on crown, according to an embodiment of the invention.

[0065] Fig. 7 is a cross-section view of a seawall showing structure-soil interaction, according to an embodiment of the invention.

[0066] Fig. 8 is a cross-section view of a seawall with a sandwich panel rib according to an embodiment of the invention. Fig. 9 illustrates three possible shapes of a seawall cross sections according to embodiments of the invention.

[0067] Fig. 10 illustrates an embodiment of joints that connect two different caisson modules.

[0068] Fig. 11 illustrates a seawall module with a height extender according to an embodiment of the invention.

[0069] Fig. 12 shows a seawall module with a height extender according to another embodiment of the invention.

[0070] Figs. 13a and Fig. 13b provide a schematic representation of a method for making an armour block for shoreline protection according to an embodiment of the invention.

[0071] Fig. 14a illustrates a method for producing the skin of a block in accordance with an embodiment of the invention.

[0072] Fig. 14b illustrates a method for producing the skin of a block in accordance with another embodiment of the invention.

[0073] Fig. 15 illustrates an embodiment of on-site underwater installation of a block according to an embodiment of the invention.

[0074] Fig. 16a is a top view of the basic block geometry for shoreline protection according to an embodiment of the invention.

[0075] Fig. 16b illustrates views of the basic block geometry of Fig. 16a.

[0076] Figs. 17a, 17b, 18a, 18b, 18c, 19a, 19b, 19c, 20a, 20b, 20c, illustrate views of blocks of different shapes according to further embodiments of the invention.

[0077] Fig. 21 is a cross section of an infrastructure for shoreline protection which can be realized with the invention.

[0078] Fig. 22 is a top view of interlocked blocks according to an embodiment of the invention.

[0079] Fig. 23 illustrates blocks in a multi-layer arrangement in front of a seawall.

[0080] Fig. 24 illustrates blocks forming one layer in a uniform checkered arrangement above a smooth filter layer.

[0081] Fig. 25 illustrates blocks forming one layer in a uniform checkered arrangement above a rugged filter layer.

[0082] Fig. 26 illustrates blocks randomly arranged on a rugged filter layer.

[0083] Detailed description of the figures

[0084] Fig. 1 illustrates an embodiment of a seawall for coastline protection against sea level rise, sedimentation, and / or erosion. The seawall includes a plurality of caisson modules 1 connected by joints 2. Each caisson module 1 includes an outer skin 3 encasing an internal reinforcing rib structure of parallel ribs 4 and a filler material 5 such as soil.

[0085] In Fig. 2 a cross-section view of the seawall according to an embodiment of the invention is shown. The caisson modules are placed onto a rubble mound 6 that distributes the forces applied by and onto the seawall to the sea ground 7. The height of the modules is chosen depending on the initial sea level 8, the sea sided level rise 9, the sea-sided half of the wave height 10 and the height of the wave run-up and storm surge 11 . Fig. 2 further shows the composition of the skin and one internal reinforcing rib structure, which includes two side surfaces 12 made of composite skins, one top surface 13 composite skin, one bottom concrete skin 14 having two edge beams 20, four diagonal composite struts 15 which diagonally connect different surfaces of the skin, two vertical composite struts 16 connecting top / bottom surfaces of the skin, one horizontal strut 17, and four horizontal composite tendons 18. Depending on the height of the seawall and the rib spacing, the number of diagonal struts and horizontal tendons can vary. Therefore, the number of struts and tendons reported above are preferred for a module having a height from 15 to 20 meters. The arrangement and composition of the internal reinforcing rib structure, as described below, are optimised to absorb the forces applied onto the seawall with the lowest quantity of composite material.

[0086] Fig. 3 shows the downward-directed resultant force 19 of the soil weight and buoyancy. Said force 19 is transmitted through the bottom concrete skin 14 to the rubble mound 6. The bottom skin 14 is designed as a reinforced concrete slab and has two edge beams 20 which protect the lateral composite skins during transportation and installation.

[0087] Fig. 4 shows the forces 21 on the side faces of the module resulting from the soil pressure and static water pressure. Said forces 21 are directed outward and balanced by horizontal tendons 18 which connect the two lateral skins 12 via the vertical struts 16. The tendons preferably have strap loop anchors 22.

[0088] Fig. 5 illustrates the force 23 acting on the lateral skin 12 due to the sea-sided dynamic water pressure, resulting from the waves. This lateral force 23 is transmitted by the two diagonal 15 and one vertical 16 struts to the concrete bottom skin 14. Said bottom skin transmits said force with the aid of the weight of the soil to the rubble mound 6 via vertical compression and horizontal friction in the interface between bottom skin 14 and rubble mound 6. Depending on the height of the seawall and the rib spacing, the number of diagonal struts can vary.

[0089] Fig. 6 illustrates how loads 24 e.g., from road traffic, possibly applied on top of the module, are transmitted by one horizontal strut 17, via the two upper diagonals 15 and two vertical 16 struts and one horizontal tendon 18, to the bottom skin 14, and further to the rubble mound 6.

[0090] Fig. 7 illustrates schematically the interaction between the skin and struts of the internal structure of the caisson modules and the soil contained in each module. Particularly, this interaction is activated by primarily tuning the relevant stiffnesses of the two lateral skins 12, the diagonal struts 15, and the soil 5, to provide the necessary confinement of the encased soil. Said interaction is represented in Fig. 7 by springs 25. Structure-soil interaction 25 allows the structural activation of the soil 5 and thus partial relief of the internal composite structure and associated possible reduction of its cross sections and material quantity use.

[0091] Fig. 8 shows another embodiment of the internal rib structure of each module. Alternatively or in addition to the strut-tendon system shown in Figs. 2-7, the ribs can be designed with composite sandwich panels 26 which merge strut and tendons into flow-of-forces directions 27. The areas 28 between the flow-of- forces directions are left empty to reduce material use.

[0092] Fig. 9 shows three cross sections of three different possible shapes, 29a, 29b, 29c, of the caisson modules. The cross section of the caisson module is preferably rectangular to basically optimise weight (29a). However, the shape can be varied to adapt to local conditions, e.g. by enlarging the base to better distribute stresses (29b), or curving the sea-sided skin to reduce wave overtopping (29c).

[0093] In Fig. 10 the joints 2 between two different caisson modules are shown. Said joints 2 are made of concrete. An aim of said joints 2 is to allow and compensate for horizontal 30 and vertical tolerances of the module position.

[0094] Figs. 11 and 12 show two embodiments of possible moderate and significant extenders of the wall height. The height of the seawall is usually designed for an expected sea level rise in a hundred years, line 9a. If, during the service life, a slightly or significantly increased rate of the rise is observed, line 9b, a moderate or significant vertical extension of the seawall is required to keep a sea level difference across said seawall. The extenders are composed of outer skins 12, ribs 4, and are filled with soil 5, as is the case for the caisson modules 1 (Fig. 1 ).

[0095] According to the embodiment of Fig. 11 a moderate vertical extension is reached by adding an L-shaped height extender 31 to the top of the already existing caisson module 1. The ribs of the extender 31 comprise struts organized in a truss configuration 32 supported onto the module by truss supports 320 that geometrically coincide with the joints of the diagonal struts 15 of the caisson module and thus ensure load transmission through the caisson module 1 down into the ground. A precondition for this extension is that the design of the existing seawall module already anticipates a possible future extension and is thus dimensioned to absorb the additional forces.

[0096] According to the embodiment of Fig. 12 a significant extension of the wall height may be reached by adding another L-shaped height extender 33 to the caisson module 1 . This extender 33 is of particular interest when the observed rate of increase of the sea level rise 9b is significantly higher than expected. Note that with increasing sea level, the wave hight 10 and height of wave run-up and storm surge 11 also increase. The extender 33 comprises a leg 35 that stands itself on the rubble mound, discharging part of the load directly on the ground. Similar as in the previous case shown in Fig. 11 , the extender 33 comprises a strut-truss configuration 32. The space between caisson module 1 and the extender 33 is filled with concrete 36 to compensate for tolerances and ensure a full composite action of modules 1 and extender 33.

[0097] The extender 31 is positioned only on the module, whereas the extender 33 is on the module plus on the rubble mound. The lightweight height extender modules 31 and 33 shown in Figs. 11 and 12 can also be used to upgrade existing concrete seawalls.

[0098] The following figures (Figs. 13 - 20) concern an armour block for shoreline protection and a method for making said block.

[0099] Fig. 13a illustrates a rigid skin 37 of a schematic block, the skin being made of a lightweight material, such as fibre-polymer composites, and encasing an internal volume 38. The internal volume 38 is filled with a suitable filler material, such as unreinforced concrete, to form a block for shoreline protection. The skin 37 comprises an opening 39 through which the filler material is introduced in the internal volume 38. This scheme of Fig. 13 is applicable to different shapes. In certain embodiments, the opening 39 can be drilled onsite.

[0100] Fig. 13b illustrates the step of introducing the filler material F into the skin 37. Fig. 14a illustrates a method for producing the rigid skin of schematic shape 37, wherein a robotic arm 42 is introduced in a skin mould 41 and the short-fibre skin material is sprayed on the internal surface of the mould 41 by a sprayer 40 mounted on the robotic arm 42. In the shown embodiment, the mould 41 is closed by a flexible membrane 43; a line 44 allows extraction of the emissions and subsequent injection of hot air for accelerating the curing of the skin material. Through this method, the skin 37 may be manufactured jointless in one step except for the upper surface including the opening 39 (see Fig. 13) which may be subsequently bonded to the skin.

[0101] Fig. 14b illustrates an alternative method wherein the rigid skin of schematic shape is produced by resin transfer moulding (RTM), preferably high-pressure RTM (HP-RTM) or compression RTM (C-RTM). RTM is a method of transferring a liquid thermoset resin into a closed mould containing the dry fibres, where the liquid resin takes the desired shape. RTM allows to make several parts 45 of the skin 37, which subsequently are bolted or bonded together at joints 46 preferably in an automated process.

[0102] Fig. 15 shows a preferred method for producing the block of schematic shape onsite. A rigid skin 37, which has been produced for example with the process of Fig. 14a or Fig. 14b, is transported to the installation site, submerged below the water line 50 and placed on the filter layer of the rubble mound 48, in a desired operative position 47. During this step, the skin 37 is filled with seawater to facilitate handling. A subsequent step of the method includes pumping the filler material into the skin 37 through a line 49 until the filler material expels and replaces the water contained in the skin 37, thus forming the block directly on site. Clearly, the great advantage of this embodiment is that transportation and handling of the heavy block after completion is not required. A small unfilled volume 51 is left above the opening of the block, which may be populated by living organisms, thus improving the environmental compatibility.

[0103] Fig. 16a and Fig. 16b show a preferred basic shape of a block 500 for shoreline protection. The shape 500 includes a first base face 53 and a second base face 54. The two faces 53, 54 have two contours with a shape of two ellipses 170, 180 twisted by 90° relative to each other. The first face 53 and the second face 54 are connected by a side surface 52 extending around the main axis A-A of the block. This basic shape 500 can be regarded as a twisted cylinder.

[0104] Various embodiments of the shape of the block can be regarded as variations from the basic shape of Figs. 16a, 16b. The basic shape 500 is preferably used for producing multiple variants of derivative shapes, represented in Figs. 17-20, each of which has its specific application. The novel method of producing rigid skins facilitates this shape variation.

[0105] Fig. 17a and Fig. 17b illustrate a block 501 according to a variant wherein the face 53 includes a protrusion 55 and the face 54 includes a recess 56, both the protrusion 55 and the recess 56 extend along the main axis A-A of the block. The skin of the protrusion 55 is open on the top surface to enable filling of the block. The shape and size of the protrusion 55 and recess 56 are complementary, so that the protrusion 55 of one block 501 can engage the recess 56 of a next block. This engagement between adjoining blocks has the effect of shear keys, i.e., increasing the shear resistance against wave action in a multi-layered arrangement of blocks (Fig. 23).

[0106] Figs. 17a, 17b illustrate another preferred feature wherein the block 501 has recesses 57 on the side surface 52. In the shown embodiment, the block has four recesses 57 around the side surface 52, thus forming a side pattern of protrusions and recesses for interlocking of adjacent blocks. Preferably the recesses 57 have a conical shape. Each recess 57 may be regarded as the result of subtracting a conical portion from the sides of the basic shape. Corresponding to the recesses 57, the base faces 53, 54 have cutouts from the basic elliptical contour. This feature of side recesses 57 increases the hydraulic stability of the block.

[0107] Fig. 18a, Fig. 18b and Fig. 18c illustrate a block 502 according to a variant of the embodiment of Figs. 17a, 17b wherein the block 502 includes a lateral protrusion 58 in the upper half of the block, obtained by extending the minor half axis 250 of the ellipse 170. The side surface 52 connects the lateral protrusion 58 of the face 53 on which the protrusion 58 extends to the mid-height of the block. The protrusion 58 is preferably present only in the upper half of blocks placed in the first row of a multi-layered arrangement where the protrusion is directed towards the waves (Fig. 23), providing a decrease of the roughness coefficient of the block that results in increased resistance to wave overtopping.

[0108] Fig. 19a, Fig. 19b and Fig. 19c illustrate a block 503 according to a variant wherein the block 503 includes an inclined vertical protrusion 59 extending on a plane inclined by an angle ‘a’ less than 45° with respect to the face 53. The opening 39 is introduced in the skin of the inclined face 59 for the block filling. The protrusion 59 confers a reduced roughness coefficient to the shape and thus improved resistance to wave overtopping, in case of a single layer arrangement (Fig. 24).

[0109] Fig. 20a, Fig. 20b and Fig. 20c illustrate a block 504 according to another variant including two vertical protrusions 290, 291 projected from both the block faces 53, 54. The protrusions 290, 291 extend along the main axis of the block 504 and include two respective caps 292, 293 connected to the elliptical contours of the faces 53, 54 by means of two respective connection surfaces 60, 61. These connection surfaces 60, 61 have a curved shape in a cross section taken on a plane including the main axis of the block 504. The shape of this block 504 facilitates a random positioning of a single layer of blocks (Fig. 26). Preferably, the skin of blocks having this shape is drilled to form the opening 39 on site at the highest point.

[0110] Fig. 21 illustrates an embodiment of a seawall infrastructure 101 according to the invention. The structure includes a plurality of caisson modules 100, said modules 100 having preferably a hybrid structure as the modules 1 shown in Fig. 1 , with the internal reinforcing rib structure described in Figs. 2-8. The caisson modules 100 stand on a filter layer 104, preferably made of rubbles, that protects a core 105 made of finer materials. A plurality of blocks, preferably including a composite skin and a concrete filler, are placed above the filter layer 104, both in front 103 and on the back 110 of the caisson modules 100. Blocks can be arranged both in a single layer (Fig.24) or in multiple layers (Fig. 23).

[0111] Fig. 22 shows a top view of an embodiment of how the blocks can interlock thanks to their recesses and protrusions, providing mechanical resistance against waves attack and a proper portion of void spaces 201 that allows desired wave energy dissipation.

[0112] Fig. 23 illustrates an embodiment of a plurality of blocks 501 and 502 interlocked in more than one layer and installed in front of a caisson module 100. The blocks 502 are always placed in the first row and oriented so that the lateral protrusions 58 face the open sea and the wave overtopping is thus reduced by the protrusions 58. The multi-layered arrangement of the blocks in front of the seawall also reduces the dynamic wave forces on the seawall.

[0113] Fig. 24 shows an embodiment of a plurality of blocks 501 and 503 interlocked in a single layer and installed on a smooth filter layer 104 of a seawall or breakwater infrastructure. The blocks 501 do not have the shear keys (protrusions 55 and recesses 56) in this case. The protrusions 59 of the blocks 503 are directed against the waves in order to reduce the wave overtopping.

[0114] Fig. 25 represents an embodiment of a plurality of blocks 501 (without shear keys) and 503 interlocked in a single layer and installed on a filter layer 104 which is not sufficiently smooth to accurately place the blocks and allowing a proper interlocking of the blocks. In such a case, a grating 62 preferably made of composites, is arranged on the filter layer 104 as a support for said blocks.

[0115] Fig. 26 shows an embodiment of a plurality of blocks 504 installed on the filter layer 104. The blocks 504 can be randomly positioned, such possibility represents an advantage particularly on rugged or curved filter layers where blocks engagement of blocks 501 to 503 would be more difficult.

Claims

CLAIMS1 ) A seawall module (1 ) for coastline protection, the seawall module comprising an outer rigid skin (3), an internal reinforcing rib structure (4) and a filler material (5), wherein the internal reinforcing rib structure and the filler material are encased by the skin.2) A seawall module according to claim 1 , wherein at least the side surfaces (12) and a top surface (13) of the skin are made of fibre-polymer composite, said composite preferably including any of: glass fibres, basalt fibres, carbon fibres, vinylester, epoxy resin, structural foam.3) A seawall module according to claim 1 or 2, the skin having a bottom surface (14) made of reinforced concrete.4) A seawall module according to claim 3, said bottom surface (14) having two edge beams.5) A seawall module according to any of claims 1 to 4, wherein the filler material (5) is soil.6) A seawall module according to any of the previous claims, wherein the internal reinforcing rib structure (5) includes any of: horizontal load-bearing members (17, 18) connecting opposite side surfaces of the skin; vertical members (16) connecting top / bottom surfaces of the skin; diagonal members (15) which diagonally connect different surfaces of the skin, or a combination of them.7) A seawall module according to claim 6, wherein the internal reinforcing rib structure includes a plurality of reinforcing assemblies, each assembly including a combination of horizontal, vertical and diagonal load-bearing members.8) A seawall module according to claim 6 or 7, wherein said load-bearing members include compression members, struts, (15, 16, 17) arranged totransmit compression and bending stress between different parts of the reinforcing rib structure (4) or skin, and tension members, tendons (18), to transmit tension stress.9) A seawall module according to any of the previous claims wherein said internal reinforcing rib structure comprises: a set of struts made of a composite material including diagonal struts, preferably four, vertical struts, preferably two, and horizontal struts (17), preferably one, horizontal tendons, preferably four, (18) made of a composite material, said members having preferably strap anchors that connect them with the lateral skins.10)A seawall module according to any of the previous claims, wherein the internal reinforcing rib structure includes at least one panel (26) having a composite sandwich structure.11 )A seawall module according to claim 10, wherein said panel (26) includes a peripheral frame corresponding to upper, lower and lateral sides of the reinforcing rib structure, and one or more transverse parts arranged to act as compression or tension members to distribute stress within the panel.12)A seawall module according to any of the previous claims wherein the module has a height between 5 and 20 metres, and / or a length between 15 and 25 metres, and / or a width between 4 and 15 metres, and / or a spacing of the internal reinforcing rib structure of 2.5 to 3 metres.13)A seawall module according to any of the previous claims wherein said module has a shape with rectangular cross-section.14)A seawall module according to any of the previous claims including a height extender (31 , 33), which is preferably an L-shaped member, saidextender being positioned onto the top of the module (1 ) and / or the rubble mound (35) to increase the overall height of the seawall module.15)A seawall module according to claim 14 wherein said extender includes an internal truss structure (32) for transmission of stress, wherein said extender is coupled with the internal truss structure by means of a concrete filling (36) and / or by means of nodes (320) of said truss structure of the extender that correspond to nodes of the internal reinforcing rib structure of the module, when the extender is coupled with the module.16)A seawall system including a plurality of seawall modules of any of claims 1 to 15, the modules being connected each other by means of joints (2).17)A seawall system according to claim 16, said joints (2) being made of concrete.18)A method for making a seawall module (1 ), wherein said seawall module (1 ) is preferably in accordance to any of claims 1 to 15, the method comprising steps of: a) making at least part of the outer skin (3) with a skin material and providing the internal reinforcing rib structure (4) of the same material; b) filling the outer skin with a filler material (5).19) A method according to claim 18, wherein the filler material (5) includes soil or sand, and / or the skin and rib material includes a fibre-composite material, preferably any of: glass fibres, basalt fibres, carbon fibres, vinylester, epoxy resin, structural foam.20)A method according to claim 18 or 19 wherein the step a) is performed by pultrusion or vacuum infusion of the skin and ribs (3).21 )A method according to any of claims 18 to 20, wherein the method includes:deploying the internally reinforced skin (3) obtained at step a) underwater in the installation site; the skin being filled with water during deployment; performing step b) by introducing the filler material into the skin so that water contained in the skin is expelled and replaced by the filler material. )An armour block for shoreline protection having a hybrid structure comprising a rigid skin (37) made of a first material, the skin being filled with a second material. )A block according to claim 22 wherein the first material is a fibre-polymer composite, said composite preferably including any of: glass fibres, basalt fibres, carbon fibres, vinylester, epoxy resin. )A block according to claim 22 or 23 wherein the second material is concrete. )A block (500) for shoreline protection comprising a first face (53) and a second face (54) opposite along a main axis (A-A) of the block, the first face (53) having a first contour which corresponds at least in part to a first ellipse (170), the second face having a second contour which corresponds at least in part to a second ellipse (180), wherein the first ellipse (170) is rotated relative to second ellipse (180), and the block comprises a side surface (52) connecting the first face (53) and the second face (54). )A block according to claim 25 wherein said first ellipse (170) is rotated of 90° relative to said second ellipse (180). )A block (501 ) according to claim 25 or 26 wherein one of the first face (53) and second face (54) includes a protrusion (55) and the other face includes a recess (56), the protrusion and the recess having a complementary size and shape so that the protrusion of one block (501 ) can engage the recess of an adjoining block to provide interlocking of blocks.8) A block (502) according to any of claims 25 to 27, wherein at least one of the first face (53) and the second face (54) includes a recess (57) or protrusion (58) relative to the elliptical contour and said side surface (52) connects the recess or protrusion (58) to the opposite face. 9)A block (503) according to any of claims 25 to 28 wherein at least one of the first face and second face lies on a plane perpendicular to the main axis or on a plane forming an angle a with respect to a plain perpendicular to the main axis, said angle a being less than 45°. 0)A block (504) according to any of claims 25 to 29 including at least one of a top cap (292) and a bottom cap (293), wherein the cap is a region of the first face or second face projected from the plane of said first ellipse or second ellipse, and connected to the first face or second face by means of a connection surface (60, 61 ). 1 )A block having the shape according to any of claims 25 to 30 and having the hybrid structure according to any of claims 22 to 24. 2)A method for making the hybrid block of any of claims 22 to 24 or claim 31 , the method comprising: a) making an outer rigid skin (37) with a skin material; b) filling the skin with a filler material (F), obtaining the item which includes the filler material, preferably concrete, encased by the skin (37). 3)A method according to claim 32 wherein the step a) comprises any of the following: a.1 ) fibre spray-up of the skin material onto a skin mould (41 ); a.2) resin transfer moulding (RTM) of the skin (37) or of different parts of the skin to be subsequently bonded together;a.3) blow moulding of the skin material to produce the skin (37). )A method according to claim 32 or 33 wherein the method includes: deploying the outer rigid skin obtained at step a) in the installation site above water or underwater; performing step b) at the installation site by introducing the filler material into the skin. )A method according to claim 34, wherein the method includes: deploying the outer rigid skin obtained at step a) underwater in the installation site, the skin being filled with water during deployment; performing step b) by introducing the filler material into the skin so that water contained in the skin is expelled and replaced by the filler material. )A method for making a seawall infrastructure (101 ) lying on a rubble mound submerged in the sea, or a breakwater infrastructure, said infrastructure being suitable to maintain a sea level difference across that structure and / or to dissipate wave energy (101 ), the method comprising the step of installing a seawall system (100) and providing a plurality of blocks (103, 110) wherein said seawall system is in accordance with claim 16 or 17, and / or said blocks are in accordance with any of claims 22 to 31 . )A method according to claim 36 wherein the seawall or breakwater infrastructure (101 ) has a first side facing the open sea and a second side facing the coast, wherein the blocks are placed only on the first side or both on the first side and on the second side of the infrastructure. )A method according to claim 36 or 37 wherein the plurality of blocks is installed in a multi-layer arrangement on the first side of the seawall or breakwater infrastructure (101 ).39)A mould made of fibre-polymer composite for producing a block for shoreline protection with a method according to any of claims 32 to 35.

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