Device for containing granular elements

Abstract

Disclosed is a device for containing granular elements, comprising a metal mesh panel having metal wires welded together, the panel presenting at least one curvature of a first orientation and at least one curvature of a second orientation, the first orientation being characterized by a first axis and the second orientation being characterized by a second axis, the first axis and the second axis being non-collinear.

Description

[0001] The invention relates to the field of structures incorporating granular elements, such as reinforced soil structures, and can particularly be applied to a facing element of such a structure. This construction technique is commonly used to build structures such as retaining walls, bridge abutments, etc. It can also be applied to the field of cladding, which consists of incorporating granular elements along a pre-existing structure to give it a mineral appearance.

[0002] Such structures combine granular elements forming a compacted embankment, a device containing these granular elements and forming a facing, and reinforcements generally connected to the facing. The device containing the granular elements typically comprises a plurality of interconnected elements.

[0003] Various types of reinforcements, generally longitudinal, can be used: they can be metallic, for example galvanized steel, or synthetic materials, such as geotextile materials or materials containing polyester fibers.

[0004] Similarly, different types of containment devices can be used: they can also be metallic, for example in galvanized steel, or in synthetic materials, such as so-called geotextile materials containing, for example, polyester fibers. The containment device generally constitutes the external facade of the structure and must therefore be resistant to wear, in particular to oxidation, while maintaining a pleasing aesthetic.

[0005] The external facade of the structure may feature horizontal setbacks between different facing levels. It may also be inclined, generally with a larger initial ground surface than at the top of the structure, but it is also possible to design structures with overhanging facings.

[0006] The reinforcements placed in the granular backfill can be distributed at varying densities. They are secured to the retaining structure using connecting devices that can take various forms. The reinforcements are capable of transmitting high loads, up to several tons.

[0007] To fulfill its containment role, it is important that the granular element containment system exhibit significant rigidity. This rigidity is traditionally achieved through reinforcement: the arrangement of connection points between the reinforcements and the containment system increases rigidity in certain directions. However, the load distribution at these points is difficult to predict.

[0008] It is therefore known, in addition, to use a restraint device with parallel, horizontal folds or corrugations to increase mechanical resistance to stresses exerted in a given direction. This type of fold or corrugation is similar to that used in corrugated sheet metal or fencing. Restraint devices with such folds are known from US patents 8,967,917 B1 and 5,733,072 A, among others.

[0009] However, these horizontal folds do not increase rigidity in all directions. Under the pressure exerted by the granular elements, this leads to the formation of undesirable bulges in the facade. To counteract these drawbacks, restraint devices are used, consisting of a wire mesh made of very thick galvanized steel wires.

[0010] The use of very thick, pre-galvanized steel wire is problematic for several reasons. First, it is difficult to produce a mesh from galvanized steel wire with a large diameter. The welds between the wires can expose the steel through the galvanized coating, and at the cut ends, a significant portion of the mesh cross-section is unprotected and can therefore quickly develop localized corrosion. Furthermore, it is difficult to obtain large quantities of this type of wire. This generally leads to a galvanizing step after the steel mesh has been produced, which considerably complicates the construction process. Finally, using a large quantity of steel results in significant cost volatility.Indeed, the price of steel is subject to fluctuations that can prove considerable over the timescale of the completion of such a project.

[0011] There is therefore a need for a new way to increase the rigidity of a device for containing granular elements, and this in several directions.

[0012] The invention achieves this through a device having the characteristics of claim 1.

[0013] The device for the containment of granular elements is typically a facing element or a combination of facing elements for a civil engineering structure such as a reinforced soil structure.

[0014] Granular elements are preferably mineral in nature. These may include materials from quarry or mining waste, for example. They may also consist of soil suitable for vegetation growth, giving the structure a natural appearance. Finally, they may also be engineered fill. These elements preferably have a relatively small particle size distribution.

[0015] The device comprises a wire mesh panel. The panel according to the invention is a monolithic element capable of distributing a stress applied to it. A wire mesh, as defined in the invention, is a network of interlocking metal wires. These metal wires are preferably arranged in two orientations, for example, two perpendicular orientations, so as to form the mesh network in the manner of a wire netting.

[0016] The mesh size of this network must be small enough to contain the granular elements. If the granular elements have a finer grain size than the wire mesh spacing, the wire mesh can be reinforced with a secondary mesh having a finer mesh size than the granular elements: the wire mesh can be combined with a secondary mesh having a smaller characteristic mesh size than the wire mesh. Such a secondary mesh can be less rigid and can be chosen, for example, from a woven mesh, a biomat, or a geotextile.

[0017] The nodes of the wire mesh network are secured by welds between the wires. Preferably, this weld is a non-reinforcing weld, such as an electrofusion weld. A non-reinforcing weld ensures interpenetration of the wires, resulting in greater strength and improved stress transmission.

[0018] The wire mesh can contain wires of different diameters to provide varying degrees of rigidity depending on the direction of stress. This allows the mesh to be adapted to its intended use.

[0019] The device's panel features a series of parallel folds in the lattice, for example, horizontal ones, forming a primary curvature. This lattice curvature makes it a three-dimensional object and significantly increases its rigidity by limiting its tendency to deform in a direction other than that of the curvature. From a mechanical point of view, this curvature is equivalent to that of a beam.

[0020] The panel also features a series of folds in the lattice parallel to each other but not parallel to those of the primary curvature, forming a secondary curvature. This second curvature acts similarly to the first, increasing rigidity in an additional direction.

[0021] If the wire mesh has wires in two directions, the bends are made in both directions. This advantageously allows at least one wire to be positioned along each bend, thus reinforcing the structure.

[0022] In order to be able to create curves in different directions, several solutions are possible.

[0023] In a preferred embodiment, said at least one first-orientation bend leads a limited number of wires, preferably a single wire, out of the plane of the lattice before bending. The out-of-plane wire(s) are advantageously shorter than the others so as to allow the at least one second-orientation bend to be made at a level of the panel where this wire(s) are not present.

[0024] Alternatively, the first and second orientation curvatures can be combined into a multiple curvature such as a dome. A dome-shaped deformation in the truss is highly advantageous from a rigidity standpoint. It can be achieved by stamping or, for example, through 3D printing techniques for a shell.

[0025] Thus, while the axes of the different curvatures are preferably straight, they can certainly be curved.

[0026] According to a third alternative, the first and second orientation curvatures are achieved by grafting elements onto the lattice a posteriori. These elements can be V-shaped and welded onto a lattice that already has folds in another direction.

[0027] The device according to the invention has increased rigidity due to its geometric shape. This rigidity can compensate for a smaller wire diameter, which is particularly advantageous as mentioned above. The wire diameter of the individual wires in the mesh is preferably greater than 4 mm to ensure minimum strength. However, it is preferably between 5 and 8 mm and in any case less than 12 mm, unlike the wires used in prior art meshes, which traditionally have diameters of up to 14 mm, or even 18 mm. This allows the mass of metal used to be reduced by more than half, while also eliminating the need for a subsequent galvanizing step, as explained above.

[0028] The device for containing granular elements according to the invention preferably comprises several first-orientation bends and / or several second-orientation bends. According to the invention, the mesh comprises a substantially flat portion, and these bends are arranged to guide a metal wire out of the plane of said portion of the mesh, preferably substantially parallel to said plane.

[0029] The wire outside the plane is shorter than the majority of the wires in the wire mesh. This allows for the generation of a bend in a different direction, at a level of the plane extending beyond the wire.

[0030] At least one curve can lead a portion of the device according to the invention out of the plane intended to become the facade of the structure in which it is to be incorporated. This portion can contribute to the robustness of the structure and improve the overall stability.

[0031] At least one curvature can also induce a fold above the granular elements. This fold can both protect the granular elements and distribute the load in the event of an impact on the facade.

[0032] Said at least one first-orientation curvature and said at least one second-orientation curvature may be or include folds. The folds within the meaning of the invention are curvatures that can be obtained by folding the wire mesh panel around a mandrel.

[0033] Preferably, a curvature arrangement is configured to allow the device to be self-stabilizing. Besides the obvious benefit within a structure, having a self-stabilizing device is also advantageous from a device storage perspective.

[0034] To this end, the curves can also advantageously be arranged in such a way as to allow the stacking of the devices according to the invention.

[0035] According to another aspect, the invention relates to a method of manufacturing a device for the containment of granular elements according to the invention comprising a first step of folding a wire mesh in a first direction and a subsequent step of folding the wire mesh in a second direction not collinear with the first direction.

[0036] The bending process, for example, is carried out by applying pressure to the lattice around a mandrel. The diameter of the mandrel can lead to more or less angular bends. Preferably, the bends should not be too angular, as this can damage the metal wires. Conversely, the bends should not be too gradual in order to minimize their footprint.

[0037] Advantageously, the galvanization of wires consists of a coating of zinc or a zinc-aluminum alloy. Thus, wire mesh preferably comprises wires with a metallic coating, the metallic coating being preferably chosen from zinc or an alloy containing zinc and / or aluminum.

[0038] The method according to the invention may include other steps, for example, a step of cutting a metal wire out of plane. This cutting step may occur after the first bend has been formed. However, in a particularly advantageous embodiment, the mesh is designed by anticipating future bends and by directly integrating shortened metal wires at the time of making the inter-wire weld points.

[0039] According to a third aspect, the invention relates to a reinforced soil structure comprising: a device for containing granular elements according to any one of the preceding claims, a plurality of granular elements contained by said device, the granular elements preferably being of a mineral nature, at least one metallic or polymeric soil reinforcement element.

[0040] The said metal floor reinforcement element can be made in continuity of material with the containment device.

[0041] The features described above can be implemented independently of each other or in combination with each other.

[0042] Other features, details, and advantages of the invention will become apparent upon reading the detailed description below and analyzing the accompanying drawings, in which: Fig. 1 [ Fig. 1 ] is a perspective view of a device for containing granular elements according to an embodiment of the invention; Fig. 2 [ Fig. 2 ] is a schematic cross-section of a work according to the invention and; Fig. 3 [ Fig. 3 ] is a schematic cross-section of a work according to the invention.

[0043] The drawings and description below contain, for the most part, elements of a definite nature. They can therefore not only serve to better explain the present invention, but also contribute to its definition, if necessary.

[0044] Reference is now being made to the figure 1 In the illustrated embodiment, the containment device according to the invention is used as a facing element for a reinforced soil structure. The facing element is intended to be combined with other similar elements arranged one below the other.

[0045] The element is made from a flat, electro-welded, galvanized steel wire mesh. The wires have a diameter of 6 mm. The welding process is performed without the addition of material by inducing a very strong localized electric field at the wire intersections. This causes localized heating and interpenetration of the wires. The welding can be automated and performed on a conveyor belt.

[0046] The wires assembled during the formation of the lattice were not all of the same length. Thus, in one dimension, one wire out of two has a long length 11+12 and one wire out of two has a short length l1.

[0047] The resulting lattice then undergoes a first series of folds 13 in a first direction. These folds are grouped in sets of three. The figure shows three sets of three folds, but the element may have more.

[0048] The illustrated element has a first face 10 intended to be positioned on the facade of the structure. This first face 10 is inscribed in a plane P1.

[0049] Each set of three folds is configured to form a V-shape and guide a wire 131 out of plane with the facade. This out-of-plane wire increases the horizontal rigidity of the cladding element. Horizontal rigidity is understood as resistance to deformation along a horizontal axis. Indeed, like a folded sheet of paper or a corrugated sheet metal panel, to impose a deformation along an axis perpendicular to the folds 13, each out-of-plane wire 131 must be subjected to compression or tension, which represents significant resistance.

[0050] This significant resistance, which generates an increase in horizontal stiffness, exists only on the portion of the lattice containing out-of-plane wires. It is therefore possible to easily generate a second series of folds 14 at a point on the metal lattice that does not contain out-of-plane wires. In the figure shown, this second series of folds consists of a single fold 14 that forms a second face 20 of the element.

[0051] This second face 20 which will not be apparent on the structure and is part of a plane P2.

[0052] The existence of this face generates an increase in vertical stiffness, that is to say, resistance to deformation along a vertical axis. Indeed, the wires 21 parallel to the fold 14 and included in the face 20 of the element are subjected to compression or tension when the face 10 is subjected to bending in a vertical direction.

[0053] Although on the figure 1 The element has only one fold 14 along a second curvature; this could include another fold to generate a third face on the top of the element, further reinforcing its vertical rigidity. The element could also have series of three folds along this second orientation to offset wires out of the plane, similar to wires 131 but in a perpendicular direction.

[0054] Different elements depending on the figure 1 They can be stored and transported stacked on top of each other. The deformations help to limit the gap between the elements when they are stacked, which is very advantageous.

[0055] The facing elements are used on a structure such as one of those shown in the figures 2 And 3 .

[0056] THE figures 2 And 3They illustrate schematic cross-sections of structures according to the invention. The general structure of such a structure corresponds to the structures known under the commercial reference TerraTrel ®< marketed by the company Terre Armée Internationale.

[0057] Such a work comprises a plurality of elements depending on the figure 1 arranged one on top of the other. These elements are used to contain an embankment 60 which can be made of different materials such as compacted earth 61, a mixture of earth and pebbles 62, pebbles or rock fragments 63. Depending on the embodiment, the embankment is made up of several types of backfill materials. These different types of backfill materials can be separated by a film, a fabric, in particular by a geomaterial fabric 50. This allows for structures whose appearance differs significantly and is chosen according to the desired aesthetic: according to the figure 2 A layer of topsoil 61 can be placed in contact with the facing, which can then be planted with vegetation; according to the figure 3 , one can place fragments of rock in contact with the facing which remain visible.

[0058] The structure is reinforced by flexible strips 40 which extend into the facing. These flexible strips can be arranged in a horizontal plane perpendicular or in a zigzag pattern relative to the facing.

[0059] They are preferably attached to the facing by means of connecting means arranged at the level of the offset wires 131 in order to take advantage of the increase in rigidity to the maximum and to limit the deformations which may occur due to the stresses suffered at the level of these attachment points.

[0060] They can also be attached to a wall that would be located behind the facing and where the space between this wall and the facing would be filled with backfill.

[0061] In the case of the figure 3 It may be advantageous to move the connecting devices towards the rear of the facing, taking advantage in particular of face 20. Indeed, it may be advantageous to avoid placing the flexible strips 40 in the area 63 where the backfill is in fragments of rock in order to avoid damaging these strips.

[0062] The invention is not limited to the examples described above, which are given only as examples, but encompasses all the variations that a person skilled in the art could envision within the scope of the protection sought as defined by the accompanying claims. In particular, although the example deals with reinforced soil structures, it can easily be adapted to the case of cladding applied to an existing structure for aesthetic purposes, for example, to give it a more mineral appearance.

Claims

1. Device for containing granular elements, comprising a metal mesh panel comprising metal wires welded together, characterized in that the panel is formed to have at least one first bend (13) and at least one second bend (14) the first and second bends having non parallel orientations, the metal mesh comprising a substantially planar portion, and in that the at least one first bend is arranged to guide a metal wire (113) out of the plane of said planar portion of the metal mesh, the metal wire (113) out of the plane having a length (11) less than more than half of the metal wires of the metal mesh.

2. Device according to claim 1, wherein the orientations of the first and second bends are perpendicular.

3. Device according to claim 2, wherein the at least one first bend is parallel to some of the metal wires of the metal mesh panel, and wherein the at least one second bend is parallel to some other metal wires of the metal mesh panel.

4. Device according to one of the preceding claims, wherein the metal wires are electro-welded to one another.

5. Device according to any one of the preceding claims, wherein the metal mesh comprises metal wires of a diameter greater than or equal to 4 mm.

6. Device according to any one of the preceding claims, wherein the metal mesh is associated with a secondary mesh having a mesh size of smaller characteristic dimensions than the metal mesh.

7. Device according to the preceding claim, wherein the secondary mesh is selected among a woven mesh, a biomat, and a geotextile.

8. Device according to any one of the preceding claims, comprising several first bends.

9. Device according to any one of the preceding claims, comprising several second bends.

10. Device according to any one of the preceding claims, wherein an arrangement bends is configured to allow the device to be auto-stable.

11. Device according to any one of the claims, wherein the metal mesh comprises wires provided with a metal coating, the metal coating preferably being selected among zinc or an alloy comprising zinc and / or aluminum.

12. Method for manufacturing a device for containing granular elements according to any one of the preceding claims, comprising a first step of bending a metal mesh in a first direction and a subsequent step of bending the metal mesh in a second direction that is non-parallel with the first direction, as well as a step of arranging a bend along the first direction to guide a metal wire out of the plane of the substantial planar portion of the metal mesh.

13. Reinforced soil structure comprising: - a device for containing granular elements according to any one of claims 1 to 11, - a plurality of granular elements contained by said device, the granular elements preferably being mineral in nature, - at least one soil reinforcement member of metal or polymer.

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