FR2883309A1 - Anti-erosion device for use as beach base stop to break e.g. wave energy, has transversal independent cells integrated to support layer by sticking envelopes of cells on layer, where envelopes are in permeable geotextile - Google Patents

Abstract

The device has cylindrical transversal independent cells (10) integrated to a support layer (9) by sticking envelopes of the cells on the layer. The lateral walls of the cells are independent from one another. The lateral walls are connected to the layer by transversal connection zones. The envelopes of the cells are in permeable geotextile. The cells present reduction of their frontal profile at one of their ends. An independent claim is also included for an anti-erosion device installing device.

Description

46S9FDISI'.doc

  The present invention relates to the field of submerged devices for combating the erosion of the shore of a body of water such as the sea, a river or a lake.

  More particularly, the invention relates to a particular embodiment of a device for beach foot abutment to break the wave energy and / or current and to help stop the departure of the constituent material of the shore.

  For example, as part of a seaside shore, the anti-erosion device serves as a beach foot stop to break the energy of offshore waves which, if not lowered in energy, would irreversibly damage the shore. In addition, the device makes it possible to stop the departure of the sand, gravels or pebbles constituting the seabed close to the shore and the beach, departure caused by the movement of surf of the water.

  We already know submerged devices to fight against marine erosion, formed by concrete blocks arranged one by one and stacked one above the other.

  Such devices require heavy means, such as cranes in particular, to arrange these blocks on the seabed. They are also very long to implement, because to achieve a device of several hundred meters, the number of operations is very important. In addition, the concrete blocks, which are generally of a large size, must be brought to the site, which is expensive and difficult handling.

  In addition, these blocks have a specific shape that may be unsuitable for the rugged reliefs of the seabed on which they will be placed. As a result, the underwater device thus formed does not have a contiguous stack of blocks, having a multitude of spaces between the blocks. The presence of these spaces between the blocks does not allow to achieve effective retention of sand since it can flow freely through these spaces.

  The cubic blocks generally used in the context of these devices have the disadvantage of having a vertical lateral surface, perpendicular to the direction of progression of the waves and / or the current. This has the effect of causing a "wharf effect" which is manifested by the digging of a pit along the device, to the right of the vertical face of the blocks. After a while, the digging of this pit can threaten the balance of the device, the blocks tend to tilt into the pit and dug by the effect of dock, making the device out of use.

  US 6,186,701 discloses an elongated single-compartment tubular device formed of a water-permeable fabric for retaining sand that is filled with water prior to being filled with sand. Thus, this device set up and filled with sand, allows for continuous retention of sand over long lengths.

  However, the implementation of such a device proves tricky, especially when sand filling the device. Indeed, the device has a single cavity to fill with sand, which requires to perform the filling in one long operation. It is impossible to adapt in length the device, since it is in a single cavity, previously made to measure for the site to protect.

  This device also has the disadvantage of a delicate maintenance in case of laceration of the textile. Indeed, since the device has only one cavity, if it is damaged by any rock or lacerated by a malicious person, it will irremediably empty its sand content, making the device erosion control completely inoperative.

  The problem proposed and solved by the present invention is to provide a device that adapts easily to the waterbed and whose length can be easily modulated according to each site to protect.

  According to another aspect, the invention aims to provide a device which, in case of laceration, is not irreparably damaged and put out of use in its entirety.

  Another object of the invention is to provide a device easily integrable to a site without denaturing or preventing any activity on the shore to protect.

  The invention further seeks to provide a device having a high stability, very weakly subject to the effect of dock and effectively protecting the shore.

  To achieve these and other aims, the present invention provides an anti-erosion device intended to be immersed on an aquatic background at a distance from a shore, capable of producing a closed volume for containing sand, comprising an elongate support layer. and closed transverse cells, generally cylindrical and integral with the support web.

  In case of laceration, a single cell is damaged, which does not compromise the entire anti-erosion device in use, waiting for repair by a diver.

  In addition, the use of independent cells makes it possible to adapt to each site the length of the anti-erosion device, by cutting, for example, the device along a cell when the length of the this one is enough.

  This is also very useful if it is necessary to preserve a channel for boats for activities taking place on the shore. The work can be easily interrupted at any place, keeping all the efficiency at the adjacent portions.

  The dimension of a cell in its longitudinal direction, that is to say in the width direction of the support ply, is substantially equal to the width of the support ply.

  The dimension of a cell in the direction of the length of the support ply is limited by two interruptions oriented substantially along the width of the support ply and separating it from the two adjacent cells. This distance may be smaller, equal to or greater than the dimension of the cells in the direction of the width of the support web.

  It may however be preferred that the dimension of the cells in the direction of the length of the support ply is less than their dimension in the width direction of the support ply.

  In addition, the side walls of the adjacent cells may advantageously be independent of one another, connected to the single support ply by separate transverse connection zones.

  The proposed device thus has great flexibility in the direction of the length of the support web, to adapt to the aquatic background, in particular to adapt to the reliefs of the bottom on which it is placed.

  According to the invention, the envelope of the transverse cells may be made of permeable geotextile, the mesh of which is sufficiently spaced to allow the water to pass, and sufficiently tight to retain the sand.

  The envelope of the anti-erosion device in geotextile is easily colonizable by any aquatic organism such as shells, crustaceans, algae and more generally any aquatic plant. The anti-erosion device thus integrates perfectly with the site without denaturing it, nor harming the local ecosystem.

  The use of geotextile for the anti-erosion device makes it resistant to all types of media, even saline media when the anti-erosion device is placed on a seabed at a distance from a coastline.

  The anti-erosion device thus produced is also inexpensive, of great flexibility and of a reasonable weight.

  465 ') FIWI'.doc Advantageously, the transverse cells may have a reduction of their frontal profile at at least one of their ends, preferably their end intended to be oriented towards the open sea.

  This frontal profile reduction allows the anti-erosion device to effectively break the "bottom" energy of waves or currents moving towards the shore and which, in the absence of anti-erosion device, would irreparably damage it. In addition, the anti-erosion device is thus provided with a base on the aquatic background wider than its top, which gives it a high stability even when a strong energy supply by a current and / or waves.

  According to the invention, the transverse cells are made integral with the support ply by bonding the envelope of the transverse cells to the support ply, or by connecting seams.

  The erosion control device thus proves to be fast and easy, and does not generate high manufacturing costs.

  According to a first embodiment of the invention, the reduction of the frontal profile can be achieved by a plurality of connection seams between the envelope of the transverse cells and the support ply in the longitudinal direction of the transverse cells, the number of seams of the linkage being maximal at the ends of the cells and decreasing in the longitudinal direction of the cells to the mid-length of the cells where it is minimal.

  It is thus easy and inexpensive to achieve a frontal reduction of the cells in their longitudinal direction. In addition, the transverse cells are thus provided, at their ends with a frontal reduction, secondary transverse cells of reduced volume and therefore less rigidity. The fact that these secondary cells have a lower rigidity will, when digging a pit by a quay effect, these secondary cells are deformed to closely match the shape of the pit thus dug. The wharf effect is thus considerably lessened.

  According to a second embodiment of the invention, the reduction of the frontal profile can be achieved by an inclined face. Such a structure is fast and economical and above all very simple.

  Advantageously, it is possible to practice on the inclined face a fold of the envelope, held by a breakable seam intended to yield under a certain stress in tension or to be sliced by a plunger. The ends of the cells can thus also, when digging a pit by a quay effect, to deform to faithfully mimic the shape of the pit thus dug.

  The seam making it possible to carry out the folding of the envelope may be cut by a plunger once the erosion protection device has been put in place, or may have a resistance such that it will break itself under a greater tensile stress. less strong, after some time spent degrading in an aquatic environment.

  It should be noted that the two embodiments described above for the reduction of the frontal profile of the transverse cells can be made jointly on the same anti-erosion device.

  According to the invention, the connection seams, in the longitudinal direction of the cells, can be made so that the weight of the filling sand of the cells compresses them. This ensures a good durability of the anti-erosion device. The seams, not working in tension, are less inclined to yield or tear any part of the anti-erosion device. In addition, it allows not to damage the device during its introduction and more particularly when it is filled with sand and water to inflate the transverse cells.

  Advantageously, the cells may have on their top at least one filling orifice to which is connected a flexible filling chimney. This allows easy filling of the cells one by one, ensuring a good distribution of sand in the cells and therefore a better filling.

  Advantageously, the anti-erosion device according to the invention may comprise anchoring means. The anchoring means make it possible to fix and maintain the anti-erosion device on the aquatic bottom, so that it is not carried away when it is put in place by currents and / or waves. In addition, this ensures that it remains in place even in case of storm.

  According to the invention, the anti-erosion device may contain sand, forming a protruding structure on the aquatic bottom and generally parallel to the shore. The parallel arrangement of the beach allows efficient frontal absorption of wave energy and / or shore-side currents.

  Advantageously, the top of the structure may be at a distance of about 1.5 m to about 2.5 m below the surface of the water. Such an arrangement makes it possible to guarantee an absorption of the "bottom" energy of the waves, which energy is the most damaging for the shore. In addition, provided this arrangement, the anti-erosion device does not interfere with activities on the shore since it can easily be passed by small boats and swimmers for example.

  Advantageously, a device for laying an anti-erosion device according to the invention may comprise: a floating barge comprising a mandrel on which is wound the anti-erosion device deflated and devoid of sand, means for pumping water for injecting water into the submerged cells, means for pumping sand and water for injecting via a discharge line a mixture of water and sand into the submerged cells previously filled with water.

  The anti-erosion device is easily transportable for its implementation off a shore. The injection of water by a pumping device into the submerged cells makes it possible to effectively maintain the anti-erosion device on the aquatic bottom. A mixture of about 20% sand and about 80% water is then injected into the anti-erosion device. Sand is a material that has the advantage of being present on a majority of aquatic sites: there is therefore no need to worry about transporting and storing on the site this raw material.

  During the filling of the transverse cells by the mixture of water and sand, the water will be evacuated through the permeable geotextile, and the sand will be retained in the transverse cells.

  Advantageously, the outlet pipe of the sand and water pumping means may have a diameter smaller than that of the flexible cell filling chimney, thus constituting an increase in section. This allows a homogeneous filling throughout the transverse cell to be filled. Indeed, the driving section of the mixture of water and sand increases, the speed of the fluid decreases, which makes it possible not to cause a pile of conical sand just vertically under the filling orifice.

  According to the invention, the laying device may further comprise a descent channel for guiding the anti-erosion device running from the mandrel of the barge. This prevents a flotation effect of the anti-erosion device during its establishment on the site to be protected, which already allows in part to fill the cells in permeable geotextile and to apply the anti-erosion device along its length on the aquatic background.

  Advantageously, the descent channel is articulated on the barge so as to allow pitching and / or roll of the barge while connecting the barge to the seabed arsorrn background. This allows the application along its entire length of the anti-erosion device on the aquatic bottom and this regardless of the movements of the barge driven by those of the surface of the water.

  Other objects, features and advantages of the present invention will become apparent from the following description of particular embodiments, in connection with the accompanying figures, of which: - Figure 1 is a sectional view of an erosion control device of the prior art; FIG. 2 is a perspective view of a first embodiment of the invention; FIG. 3 is a perspective view of a second embodiment of the invention; FIG. 4 is a diagrammatic view from below showing the connection seams between the envelope of the transverse cells and the support ply in the context of the embodiment of FIG. 3; - Figure 5 is a schematic side view in longitudinal section of one end of a transverse cell; - Figure 6 is a schematic side view in longitudinal section of an end of a transverse cell according to the embodiment of the invention shown in Figure 2; - Figure 7 is a schematic side view in longitudinal section of an end of a transverse cell such as that shown in Figure 6, after digging a pit by quay effect; - Figure 8 is a schematic cross-sectional view of a cell; FIG. 9 is a front diagrammatic view of the filling of an anti-erosion device according to the invention; FIG. 10 is a diagrammatic view from above of a site protected by an anti-erosion device according to the invention; - Figure 11 is a cross-sectional view of an anti-erosion device according to the invention, in position on an aquatic background; FIG. 12 illustrates the step of setting up an anti-erosion device according to the invention; and FIG. 13 is a detailed view of a floating barge used in the device for laying an erosion control device according to the invention.

  In Figure 1 is illustrated an anti-erosion device 12 of the prior art 35 consisting of a stack of blocks 1 placed on the aquatic bottom 2 under the surface 3 of a body of water. This figure shows the quay effect.

  4 (S) I1) 1 I'.d, c The wave and / or the current progresses towards a shore according to the arrow 4 and meets, in depth, the vertical face 5 of the block 1. The current and / or the wave then tends to flow back according to the arrows 6, causing a swirling flow at the foot of the anti-erosion device 12. These vortices 6 at the foot of the anti-erosion device 12 cause the digging of a pit 8 which is successively enlarged by a pit 8a, 8b, 8c and so on over time.

  Depending on the energy of the waves and / or the force of the current, the digging of the pit 8 is more or less fast, and the block 1 will eventually tilt into it.

  The intensity of the quay effect is also due to the height H of the vertical face 5 of the block 1: the greater the latter, the greater the quay effect is important and accelerates the digging of the pit 8.

  FIG. 2 depicts an anti-erosion device 12 according to the invention, as it appears to be immersed on an aquatic background 2 at a distance from a shore, producing a closed volume for containing sand, comprising an elongated sheet 9 and closed transverse cylindrical cells 10 secured to the support ply 9. Each cell 10 comprises a casing 11 permeable geotextile, whose mesh is spaced sufficiently to allow water to pass, and sufficiently tight to retain the sand. The transverse cells 10 have a reduction of their frontal profile at their first 10a and second 10b ends.

  Each cell 10 produces a closed volume to contain sand independently of the other cells 10. Thus, in case of puncture of a cell 101, the other cells 10 are not affected, since realizing a closed volume containing independent sand. Therefore, even in case of puncture of a cell 101 of the anti-erosion device 12, it is not rendered rendered unusable or out of use. A diver can subsequently come to repair the cell 101 punctured.

  In FIG. 8, illustrating the central portion of the cell 10 in section along a plane taken along the length of the ply 9, it can be seen that the envelope 11 is connected to the ply 9 by two transverse connection zones. 13a and 13c such that seams spaced apart from each other by a distance less than the diameter of the cell 10. In this way, the side walls of the cell 10 are independent of the side walls of the adjacent cells.

  The geotextile support ply 9 is sufficiently flexible to allow the anti-erosion device 12 to faithfully follow all the reliefs of the aquatic background 2. The reduction of the frontal profile at the ends 10a and 10b of the cells 10 is performed by an inclined face 14.

  The reduction of the frontal profile of the ends 10a and 10b of the cells 10 makes it possible to progressively break the "bottom" energy of the waves which, after being passed over the anti-erosion device 12, will have a lower energy and will therefore be less harmful to the shore. In addition, such a frontal reduction of the ends 10a and 10b of the cells 10 is more hydrodynamic than the vertical face 5 of the block 1 of FIG. 1. This has the effect of significantly reducing the vortices 6 (FIG. 2) inducing the effect of quay, and thus minimize the digging of a pit at the foot of the anti-erosion device 12.

  In Figure 3 is illustrated another embodiment of the anti-erosion device 12 according to the invention. The cells 10 have at their ends 10a and 10b a reduction of the frontal profile made by a plurality of connections between the envelope 11 of the transverse cells 10 and the support ply 9 in the longitudinal direction 1-1 of the transverse cells 10. The number of connections is maximum at the ends 10a and 10b of the cells 10, and decreases in the longitudinal direction 1-1 of the cells 10 in the direction of the mid-length thereof, located on both sides at the axis II -II, where this number is minimal.

  The transverse cell 10 then comprises a main portion 10c of cells and a plurality of secondary portions 10d of cells. The secondary portions 10d of cell, of smaller dimensions, have less rigidity. Thus, in the case of digging a pit 8 at the foot of the anti-erosion device 12, the secondary portions 10d of cell will tend to deform to match the concave shape of the aquatic background 2 once dug.

  In Figure 4 is schematically illustrated the outline of the connections of the envelope 11 of the cell 10 with the web 9 support in the end zone. This is the schematic layout of the connections of the envelope 11 of the cell 10 with the support ply 9 of the anti-erosion device 12 shown in FIG. 3. It can be seen that in the vicinity of the end 10a of the cell 10, the parallel transverse connection areas 13a and 13c are further spaced from each other than in the central portion of the cell illustrated in Figure 8, and at least one intermediate connecting zone 13b parallel is added. In this way, the number of these connections is maximum at the end 10a, and decreases in the longitudinal direction of the axis 1-1 to the mid-length of the cells, represented by the axis II-II, where the number of links is minimal.

  In FIGS. 3 and 4, two cell side portions 10b and 10d are made, substantially reducing the height of the cell 10 by half. To further reduce the height of the cell 10 at its end, the number of secondary cell parts can be increased, for example by six intermediate bonding pin areas 13e-13j shown in Fig. 9, which define four abutments. of cell 10e-10h, following the two side portions of cell 10b and 10d which precede them.

  In FIG. 4, the links 13a, 13b and 13c between the envelope 11 of the cells 10 and the support ply 9 are made by gluing in a first possibility. According to a second possibility, the connections 13a, 13b and 13c between the envelope 11 and the support ply 9 are made using seams.

  FIG. 5 shows the detail of the end connection between the envelope 11 of the cells 10 and the support ply 9 by means of a seam 13d at one of the ends 10a or 10b of the cells 10, along a longitudinal edge of the web 9 support. The seam 13d is made by taking two thicknesses of the envelope 11 between which is inserted a thickness of the web 9 support. This triple seam with a return 15 of the envelope 11 under the lower face 16 of the support ply 9 avoids any risk of separation of the envelope 11 with the support ply 9, separation that could lead to loss of content of the closed volume defined by the cell 10.

  The connection of the envelope 11 with the support ply 9 at the ends 10a or 10b of the cell 110 illustrated in this FIG. 5 can be envisaged in the two embodiments illustrated in FIGS. 2 and 3.

  FIG. 6 shows an end 10a or 10b of a transverse cell 10 with a geotextile envelope 11. The inclined face 14 is formed by a fold 17 of the casing 11, held by a breakable seam 18 intended to yield under a certain stress in tension or to be sliced by a plunger. The seam 18 may be made in a thread of low resistance, or may be made in a thread that is made to weaken by partial dissolution when it comes into contact with an aqueous medium. It is for example conceivable to perform the seam 18 using a wire whose presence in a saline environment would weaken it, this in the context of the introduction of an erosion device 12 at sea.

  FIG. 7 shows the end 10a or 10b of the cell 10 shown in FIG. 6. At the bottom of the anti-erosion device 12 has widened, by quay effect, a pit 8 on the aquatic bottom 2. It is observed that the seam 18 now a fold 17 (Figure 6) has disappeared, either by breaking the wire in the aqueous medium, or because the wire was cut by a plunger. The end 10b of the cell 10 is then freely elongated and inclined to perfectly fit the inner shape of the pit 8.

  It is easily understood that subsequently, the current or the waves progressing in the direction defined by the arrow 4 will slip on the inclined face 465) FDF.Pdnc 14 of the cell 10 in the direction defined by the arrow 4a. The end of the cell located in the pit 8 is at a distance D below the aquatic background 2 and will therefore no longer be exposed to any wharf effect.

  FIG. 8 shows a detailed view of the seams 13a and 13c of FIG. 4, oriented along the longitudinal direction 1-1 of the transverse cells 10. It can be seen in this FIG. 8 that the seams 13a and 13c take the envelope 11 double and as the web 9. Once arranged on the aquatic bottom and inflated with water, the cells 10 have a height H1. However, once filled with sand, the cells 10 undergo a settlement of about one third of their height. Thus, the cell 10 shown in Figure 8 had a height H1, once filled with water, and a final height H2, once filled with sand.

  This compression of the height of the cells 10 due to the weight of the sand they contain allows crushing seams 13a and 13c and not a pull exerted thereon. Thus, by the sand filling of the cells 10 and the configuration of seams 13a and 13c, contributes to the longevity of the device, while achieving a good seal closed volumes defined by each cell 10 to contain sand.

  According to the invention, the cells 10 may have on their top at least one filling orifice 19 to which is connected a flexible filling chimney 20, as shown in FIG. 9.

  The means for pumping water and the means for pumping sand and water may consist of a single pumping device 22, initially capable of pumping only water, and capable of second time to pump a mixture of sand and water.

  Thus, FIG. 9 shows a floating barge 29 and a pumping device 22 having an outlet pipe 23. With this same pumping device 22, water is first injected and then the cells are injected once. 10 inflated by the injection of water, a mixture of water and sand is injected into the submerged cells. The outlet pipe 23 of the water and sand pumping device 22 has a diameter D1 that is smaller than the diameter D2 of the flexible stack 20 of the cells 10. This difference in diameter between the outlet pipe 23 and the flexible pipe of FIG. filling 20 allows the injection of the mixture of sand and water in the form of a diffuse cone 24 ensuring a homogeneous and complete filling of the cells 10 in water and sand.

  In the absence of this difference in diameter, the injection of the mixture of water and sand would be in the form of a rectilinear flow little diffuse, and would cause 4 (, 991) EI'.doc the pile of a a cone-shaped sand pile vertically under the filling orifice 19, which would be detrimental to the complete and homogeneous filling of the cells 10 with sand.

  In FIG. 10, the anti-erosion device 12 comprises anchoring means 25 and 26 for fixing it on the aquatic bottom 2. This allows the anti-erosion device 12 to be kept in place on the aquatic floor 2, even if if the weather conditions are bad.

  The anti-erosion device 12 is disposed substantially parallel to the shore 27 to be protected.

  In FIG. 11, it can be seen that the anti-erosion device 12 once in place forms a protruding structure on the aquatic bottom 2. The height H2 of the cells 10 is such that there remains a distance H3 of approximately 1.5 m about 2.5 m below surface 3 of the body of water. This makes it possible to let small boats or swimmers pass and not to disturb activities on the coastline to be protected. In addition, the "bottom" energy of the waves, which is the most damaging to the shore, is absorbed and / or broken by the presence of the anti-erosion device 12.

  The two possible embodiments for reducing the frontal profile of the cells 10 are used on the anti-erosion device 12 shown in FIG. 11. On the side of the shore, the reduction of the frontal profile is achieved by an inclined face 14, while on the offshore side, the reduction of the frontal profile is achieved by a plurality of connection seams between the envelope 11 of the transverse cells 10 and the support ply 9, creating secondary cells 10d.

  FIG. 12 represents a device for laying an erosion control device 12 according to the invention, comprising a floating barge 29 provided with a mandrel 30 on which the anti-erosion device 12 is deflated and devoid of sand. The cells 10 are immersed and then filled with water by means of a water pumping device located on the floating barge 29 or on another floating barge.

  Once the anti-erosion device 12 is immersed and placed on the bottom 2, a mixture of water and sand can be injected into the cells 10 according to the embodiment described in FIG. 9. The mixture of water and sand contains about 20% sand and 80% water. Such proportions for the mixture of water and sand allow a good fluidity of the mixture, allowing an easy and rapid filling of the cells 10 with sand.

  The sand of the mixture of water and sand is directly pumped on the spot in the case where the aquatic bottom 2 consists of sand. This avoids the transportation of this raw material.

  4 (,) FD! In FIG. 12, there is also a downcomer 31 for guiding the anti-erosion device 12 running from the mandrel 30 of the floating barge 29. A roller 33 articulated at the end of the downcomer channel 31 close the aquatic background 2 ensures a good placement on the aquatic background 2 of the anti-erosion device 12 perfectly marrying the relief thereof. The descent channel 31 makes it possible to avoid a flotation effect of the anti-erosion device 12 when the cells 10 thereof are deflated and devoid of sand.

  In FIG. 13, the articulation 32 of the down channel 31 on the barge 29 is better distinguished. This articulation 32, having a transverse axis 32a and a longitudinal axis 32b, allows all pitching and / or roll movements of the barge. 29 when the descent channel 31 is in contact with the aquatic background 2. Thus, even in case of disturbed weather conditions, it is possible to proceed to the establishment of the anti-erosion device 12.

  In the event of sudden degradation of the weather conditions during the erosion control device 12, making it impossible to continue operations, two solutions are possible. A first solution is to cut the anti-erosion device 12 at the edge of a cell 10 and to proceed quickly to fill all the cells 10 immersed in sand. A second solution is to immerse the mandrel 30 on which is wound the anti-erosion device 12 deflated and devoid of sand. The mandrel 30 once submerged can be anchored to the aquatic bottom 2 to be easily recovered for continued operations when weather conditions permit.

  The present invention is not limited to the embodiments which have been explicitly described, but includes the various variants and generalizations thereof within the scope of the claims below.

4659I DISP.doc

Claims (15)

  1 anti-erosion device (12) intended to be immersed on an aquatic background (2) away from a shore, adapted to produce a closed volume for containing sand, characterized in that it comprises a web (9) support elongate and closed cells (10) transverse, generally cylindrical and integral with the web (9) support.   2 anti-erosion device (12) according to claim 1, characterized in that the envelope (II) of the cells (10) cross is permeable geotextile, whose mesh are spaced sufficiently to let the water, and sufficiently tight to hold the sand.   3 anti-erosion device (12) according to one of claims 1 or 2, characterized in that the cells (10) transverse have a reduction of their frontal profile to at least one of their ends (10a, 10b).   4 anti-erosion device (12) according to one of claims 1 to 3, characterized in that the cells (10) transverse are made integral with the sheet (9) support by bonding the envelope (11) of the cells ( 10) transverse on the web (9) support.     Anti-erosion device (12) according to one of claims 1 to 3, characterized in that the cells (10) transverse are made integral with the web (9) support by connecting seams (13a-13d).   6 anti-erosion device (12) according to any one of claims 3 to 5, characterized in that the reduction of the frontal profile is performed by a plurality of connection seams (13e-13j) between the envelope (11) of transverse cells (10) and the web (9) supporting in the longitudinal direction (1-1) of the transverse cells (10), the number of connecting seams being maximum at the ends (10a, 10b) of the cells (10) and decreasing in the longitudinal direction (1-1) of the cells (10) to the mid-length of the cells (10) where it is minimal.   7 anti-erosion device (12) according to any one of claims 3 to 5, characterized in that the reduction of the frontal profile is performed by an inclined face (14).   8 anti-erosion device (12) according to claim 7, characterized in that on the inclined face (14) is formed a fold (17) of the casing (Il), maintained by a seam (18) breakable to yield under a certain stress in tension or to be sliced by a plunger.   9 anti-erosion device (12) according to any one of claims 5 to 8, characterized in that the connecting seams (13a, 13c, 13ears') II) I rdoc 13j), in the longitudinal direction (1 -1) cells (10) are formed so that the weight of the filling sand of the cells (10) compresses them.     Anti-erosion device (12) according to any one of claims 1 to 9, characterized in that the cells (10) have on their top at least one orifice (19) filling which is connected to a flexible chimney (20) of filling.   11 anti-erosion device (12) according to any one of claims 1 to 10, characterized in that it comprises anchoring means (25, 26).   12 anti-erosion device (12) according to any one of claims 1 to 11, characterized in that it contains sand, forming a protruding structure on the bottom (2) aquatic and generally parallel to the shore.   13 anti-erosion device (12) according to claim 12, characterized in that the top of the structure is at a distance (H3) of about 1.5 m to about 2.5 m below the surface (3) of the 'water.   14 Device for installing an anti-erosion device (12) according to any one of claims 1 to 13, characterized in that it comprises: a floating barge (29) having a mandrel (30) on which is wound the anti-erosion device (12) deflated and devoid of sand, - water pumping means (22) for injecting water into the immersed cells (10), - means for pumping sand and water ( 22) for injecting through an outlet pipe (23) a mixture of water and sand into the cells (10) immersed previously filled with water.   Laying device according to claim 14, characterized in that the outlet pipe (23) of the sand and water pumping means (22) has a diameter (D1) smaller than that (D2) of the chimney ( 20) flexible filling of the cells (10).   16 laying device according to one of claims 14 or 15, characterized in that it further comprises a descent channel (31) for guiding the anti-erosion device (12) unwinding from the mandrel (30) of the barge (29).   17 laying device according to claim 16, characterized in that the down channel (31) is articulated on the barge (29) so as to allow pitching and / or roll of the barge (29) while connecting the barge at the bottom (2) aquatic.