Diamond mesh for use in civil engineering in geotechnical applications

Description

DESCRIPTION of the industrial invention entitled: "Round mesh net- boidal for use in civil engineering in geotechnical applications" by: Officine Maccaferri SpA, of Italian nationality, with headquarters in Bologna Designated Inventor: Antoine GAGLIARDI filed on: April 29, 2024 * * * Field of invention The present invention relates to a rhomboid mesh net for use in civil engineering in geotechnical applications, for example in field of protection from natural hazards. The invention has been developed with particular attention, even if not exclusively, to a high-strength diamond mesh net, to construct civil engineering works such as protective barriers boulders or avalanche barriers, for covering the surface of rock walls in order to contain rock falls, for three-dimensional stabilization of land, slopes, embankments, embankments, tunnels and road constructions, for the re- installation of retaining walls of embankments, for the protection of the banks of water basins, for the construction of weirs and other debris barriers along rivers and streams and hydraulic works in general, for the construction of cages ni and other similar articles of wire mesh or comprising wire mesh, and for any other generally known civil and geotechnical use in which it is necessary to prepare a metal mesh that is resistant and long-lasting. Technological background The networks described in this document are used in the sector of civil and geotechnical works mainly for the protection from re- PROVVISIONATO & CO natural risks. For example, through such networks it is possible to avoid or at least reduce reduce the risk of rocks, debris, snow or other similar natural elements falling downstream due to natural instabilities such as landslides, avalanches, debris flows, river floods, rock falls and other phenomena of the genus king, reach and damage roads, houses, bridges, etc. or even put people's safety at risk. To this end, these networks, together to their supports, they are designed to withstand great impacts and pressures floods, such as those caused by a rockfall, a debris flow or by an avalanche that hits them. Typical, though not limiting, uses of these networks are the creation of construction of rockfall or avalanche barriers, the cladding of rock walls in order to contain rock falls, the stabilization three-dimensional of terrain, slopes, embankments, embankments, tunnels and buildings roads, the construction of retaining walls of embankments, the protection of banks of water basins, the construction of weirs and other anti-debris barriers along go rivers and streams and hydraulic works in general, the construction of gabions and other similar articles of wire mesh or comprising wire mesh, as well as any other generally known civil and geotechnical use that it must use a resistant and durable network, both for impacts and for corrosion. In the geotechnical sector, they are generally known for the above purposes mentioned, the so-called diamond mesh nets, also called mesh nets loose. The geometry of these nets is achieved by folding them into a spiral shape. a series of metal wires are crushed, which are then intertwined “avor- “tandoli” to each other to form the diamond-shaped meshes of the net. PROVVISIONATO & CO US 6279858 describes an example of such a diamond mesh net, made using metal wires, each of which is bent into a spiral crushed and intertwined with similar adjacent metal wires to form the rhomboid meshes. The metal wires that make up this known network are made made of a high-strength steel, having a breaking load of taken between 1000 and 2200 N / mm (MPa). The high strength of these wires me- tallics allows the web to maintain its three-dimensional structure sional, defined as similar to a mattress, even under conditions of high effort to. A diamond mesh net made according to the principle of ® US 6279858 is known by the trade name TECCO, produced by Geo- brugg AG. This net is made of metal wires having a breaking load of approximately 1770 N / mm and a diameter of 2 mm, 3 mm or 4 mm, with meshes that can have dimensions of the diagonals of the rhombuses respectively- mind approximately 62 x 95 mm, approximately 83 x 143 mm or approximately 102 x 177 mm. Another diamond mesh net is known by the commercial name ® 3STUTOR, produced by 3S Geotecnia y Tecnologia SL This network is made ized with metal wires having a breaking load of 900 N / mm and a dia- meter of 2.7 mm, 3.4 mm, 4.0 mm or 4.5 mm. At the site where it is de- ® written the above mentioned 3STUTOR network http: / / www.3sgeotech.com / es / productos / mallas-de-alambre-3stutor the documents of are mentioned patent ES237412 and WO2015 / 114177 which describe the realization of a net with rhomboid (or “diamond”) meshes, which however are made with a single rope, instead of metal wires. The rope has a diameter of between 12 mm and 18 mm and the mesh size of the net is between PROVVISIONATO & CO 500 mm and 700 mm and an acute angle between approximately 50° and approximately 65°. A problem of the known diamond mesh networks which, like those mentioned above, are made with metal wires, is that as they are the higher the resistance of the wires, the greater the difficulty in making the network due to the considerable effort required to bend the wires. Despite US 6279858 describes the fabrication of wire mesh with resistance wires up to 2200 N / mm, in practice it does not appear that networks have been created with wires with a resistance value of approximately 1770 N / mm. Another problem encountered in the construction of the networks known to rhomboid mesh is that as the resistance of the metal wires increases, also their elasticity, which makes it difficult to obtain the shape of the the desired networks. A solution to this last problem is described in EP 2817455, which concerns a way of bending metal wires to form a series of elbows, to make the net even flatter than the previous ones- mind notes. In EP 2817455 the metal wires are flattened on both sides of each fold, forcing them beyond the planar surface by an angle ad- joint, for example from 10° to 30°, so that the springback of the network when the forcing stops reduces the angle and brings the network into a condition flattened. This forcing of the network threads is particularly useful when the wires are made of high strength steel with a breaking load of 2 2 ture between 1000 N / mm and 3200 N / mm. The solution described in EP 2817455 is not entirely satisfactory, however. cent, because it involves additional operations to force the wires to bend metals beyond the desired final configuration. In addition to this, the process PROVVISIONATO & CO to is not easily controllable and can give rise to a network with the shape heterogeneous. Another example of a high strength diamond mesh net, used for soil stabilization, is described in US 2007 / 210214. In in this case, the rhomboid meshes of the net are not formed by single threads metallic such as those previously mentioned in US 6279858 or the ® TECCO network, but rather from strands or cables, each of which is made up of some spirally wound metal wires. At least two of the wires that form each tre- wire or cable are made of steel with a tensile strength ranging from ac- low strength steels from 100 N / mm to high strength steels from 2200 N / mm . Within this very wide range of values, US 2007 / 210214 indicates the possibility of using a generic steel for springs, according to the DIN 17223 standard. In the only example described and il- expressly illustrated in US 2007 / 210214, the strands that form the meshes rhomboidal are formed by two metal wires each having a diameter of 3 mm and a breaking load of 1770 MPa, according to DIN Standard 2078. These features make the network very rigid, so that undergo virtually no deformation under load and such as not to re- ask for ring fasteners (e.g. cross clamps). A network having the characteristics described in US 2007 / 210214 is pro- ® produced by Geobrugg AG under the trade name Spider. It is made up of from 1x3 spiral strands, i.e. each one made up of three wrapped metal wires together in a helical shape around the common theoretical axis with a length of uniform strand pitch. The nominal diameter of each strand is of 6.5 mm, while each of the three metal wires that form the strand has a PROVVISIONATO & CO diameter of 3 mm and is made of a high strength steel 2 ® 1770 N / mm . The rhomboid meshes of this Spider net are much more ® larger than those of the above-mentioned TECCO network of the same Geo- brugg AG, as they nominally measure 164 mm (smallest diagonal) x 270 mm (largest diagonal). The manufacture of diamond mesh nets with such threads or strands of high-strength steel is difficult, if not impossible, due to the remarkable rigidity of the individual threads which, in the lower resistance networks, must however have a diameter of at least 2 mm to reach a load of nominal breaking strength, taking into account the cross-sectional area of ​​the wire, of at least 5.5 kN. As mentioned above, To make these mesh nets rhomboid with high resistance wires requires the use of very high-performance machines robust, which however show a very high rate of wear. Oc- It is also necessary to use special measures for bending metal wires. due to the fact that the high-strength steel wires or strands tend- to behave like harmonic steel wires for springs, with an elastic return remarkable stability and a very poor ability to deform plastically in so as to maintain the shape of the spiral fold. The problem of diamond mesh nets therefore remains unsolved. notes on how to increase the resistance of the networks themselves without having to increase ® significantly the mesh size, as in the aforementioned Spider net by Geobrugg AG, and without resorting to special or complex machines and often so imprecise further operations, such as over-folding of the written in EP 2817455, compared to the standard operations used for the fa- manufacturing of nets using low-strength steel wires. PROVVISIONATO & CO Exposition of the invention An object of the present invention is to solve the problems of the prior art, providing a diamond mesh net for use in civil engineering in geotechnical applications requiring high resistance of the network, as well as high manageability and flexibility, with a relatively low weight. Another object of the invention is to provide a mesh net high strength rhomboids that can be easily fabricated with existing machines normally used for the manufacture of nets with diamond-shaped meshes that use relatively soft threads. Another object of the invention is to provide a mesh net rhomboidal shape that is flexible enough to adapt to the shape uneven terrain of embankments, slopes, banks, etc. Another aim is to create a diamond mesh network that it is relatively light, in terms of weight per unit of measurement, for example be transported and installed easily and at low costs, especially in impervious areas such as mountainous areas potentially subject to landslides, avalanches, mudslides, debris flows, etc. Another object of the invention is to provide a ma- rhomboidal tiles that are economical, simple to make and long-lasting. The above-mentioned objects are achieved by the invention as defined in the claims that follow. In this description, “strand” means a twisted rope simple winding, consisting of wires wound in a helix around the same my axis; this rope is also called a "spiral rope". The axis of the strand or rope PROVVISIONATO & CO spiral can be virtual, as for example in the case of three or four-stranded wires four wires, or real, in which case it can be made of a metal wire lico, as for example in the case of seven-wire strands or spiral ropes with multiple layers of wires. According to a first aspect, a rhomboid mesh network is described. nets, also called loose mesh nets, particularly for use in engineering civil engineering in geotechnical applications, preferably in the field of protection from natural hazards. The net is made up of elongated elements that they are folded into a flattened spiral and are wrapped around elongated elements adjacent by half a turn, that is, by 180°. At least some of the elements al- long ropes or strands, each made with at least two metal wires wrapped in a helix around the same axis. Each metal wire has a diameter less than 3 mm, preferably equal to or less than 2.5 mm, very preferably equal to or less than 2 mm, more preferably equal to or less than to 1.5 mm, even more preferably equal to or less than 1.1 mm, being able to descend also below 1 mm. A network made according to the invention provides numerous advantages among which the fact that it is very resistant and at the same time light and easy to move even by hand, making installation operations easier, especially mind in the most inaccessible places and positions. Being light and flexible, The net is easily rolled up for transport and unrolled when needed on the installation site. According to a particular aspect, the metal wires of each element al- elongated can have the same nominal diameter. This allows to obtain maintain a network of remarkably uniform resistance, as well as low cost. PROVVISIONATO & CO due to the lower intrinsic cost of the strands. According to a particular aspect, the metal wires that make up the three- sheets are made of high-strength steel, with a breaking load greater than 770 MPa, preferably equal to or greater than 1500 MPa, for example equal to approx. approx. 1550 MPa. The breaking load of metal wires can be even higher. king, for example preferably equal to or greater than 1700 MPa, for example of approximately 1750 MPa, or 1860 MPa. Even more preferably, the resistance of metal wires can be equal to or greater than 1900 MPa, for example approximately 1950 MPa, for example, can reach or even exceed 2160 MPa. The high resistance of the metal wires that make up the strands with which it is made The network allows for the creation of relatively thin threads which, thanks to the their helical winding, however, guarantee high flexibility of the net, as well as its remarkable lightness. Despite the threads that form no the strands can be intrinsically elastic due to the high resistance steel resistance, the mesh as a whole demonstrates a certain plasticity which allows it to be shaped and adapted to the varying conformation of the terrain. This effect seems to be due to the fact, even if not yet fully understood, stopped, that the relatively small diameter metal wires that compose the strands can slide slightly, with friction, over each other, in in such a way as to maintain the configuration imposed on them over time, without, however, causing significant yielding of the material. According to another particular aspect, the elongated elements that com- place the net have a nominal diameter equal to or less than 5 mm, preferably preferably equal to or less than 4 mm, preferably equal to or less than 3 mm, even more preferably equal to or less than 2.50 mm, for example 2.40 mm. PROVVISIONATO & CO Metal elements of this size can be easily machined in traditional machines used to make diamond mesh nets with single metal wires. According to another particular aspect, the strands or ropes of the net are spiral ropes with simple winding with a single layer of wires, including teeth each at least two metal wires, more preferably at least three wires metallic, even more preferably at least five metallic wires, even more preferably at least seven metal wires. These spiral ropes are flexible bili and yet they are quite compact, so that they can be easily used. also usable in traditional machines for weaving hexagonal mesh nets. normally used for the manufacture of nets with single metal wires there. According to another aspect, elongated elements can have a re- protective coating. The protective coating can be metallic, for example a zinc and aluminium alloy, or plastic, for example PE, PVC or PA, or a combination of these. The coating can be made placed on each wire that makes up the strand or, alternatively or in addition reached the coating on each wire, on the entire strand. A particular example the type of coated strands is that of the so-called sheathed strands, with sheath for example of HDPE. Preferably, but not limited to, the thickness of the coating can vary from about 0.2 mm to about 0.5 mm. According to another aspect, the rhomboid meshes of the net can have dimensions equal to those of the rhomboid nets made with metal wires single rhombuses, i.e. with rhombus diagonals measuring approximately 60 x 90 mm to approximately 110 x 180 mm, with a sharp angle of the rhomboid mesh- PROVVISIONATO & CO which can be between 45° and 55°, preferably between 47° and 54°, plus preferably between 48° and 52°, even more preferably between 50° and 51°. Brief description of the drawings Further features and benefits will be detailed in the description. cut that follows a preferred form of embodiment, with reference to the di- attached signs, given as a non-limiting example, in which: - Figure 1 is a perspective view of an example strand, made with three metal wires, used to create an example of a mesh rhomboid meshes according to the invention; and - Figure 2 is a front view of some of the diamond-shaped meshes of a net according to the invention. Detailed description Referring now to figure 1, an example is illustrated strand 1, which in the industry is also sometimes called "rope", "braid" or "spi- "roidale", used for the creation of a rhomboid mesh net according to the invention. The strand 1 is made of steel and can be supplied in rolls, po- I tend to be used in the same way as the syn- metal wires for the manufacture of diamond mesh nets with the well-known machines. More precisely, strand 1, which represents a mere example, limiting, given only to better understand the invention, is constituted from three metal wires 2, all having the same nominal diameter, wound together me in helical shape around the common axis, with a step length of uniform L stranding. The strand can also be of the type in which one of the threads is central and forms a core around which the ri- are helically wrapped PROVVISIONATO & CO remaining threads of the strand. Another example of strand is for example that of the- named 1x7, consisting of seven metal wires. Naturally, the invention is not limited to the use of such a strand or spiral rope, but can comp- consider using other types of ropes, such as multi-layered spiral ropes The diameter d of each wire can be equal to or less than 2 mm, pre- preferably equal to or less than 1.5 mm, even more preferably equal to or less than less than 1.1 mm. In the example shown, the 1x3 strand has a diameter 2.4 mm and each wire 2 has a nominal diameter of approximately 0.9. The load breaking strength is approximately 1770 N / mm. In another example, not illustrated, it was advantageously used a 1x7 strand with a diameter of 3 mm whose fi- they have a diameter of 0.9 mm, always with a breaking load of approximately 1770 N / mm . Naturally these values ​​must be considered as examples. vi, but not limiting the invention, which can be made with strands or ropes other than those described here in detail. Strand 1 has its own nominal diameter D which can be equal to or less than 5mm, preferably equal to or less than 4mm, preferably equal to or less than 4mm, even more preferably equal to or less than 2.50mm, for example in the case of figure 1, equal to approximately 2.40 mm. The wires 1 that make up the strand 2 are made of steel having a resistance strength greater than 770 MPa, preferably equal to or greater than 1500 MPa, for example equal to approximately 1550 MPa. The breaking load of metal wires can be even higher, for example preferably equal to or greater than 1700 MPa, for example around 1750 MPa, or 1860 MPa. Even more preferable- In all likelihood, the resistance of metal wires can be equal to or greater than 1900 MPa, for example around 1950 MPa, as can be achieved or PROVVISIONATO & CO even exceeding 2160 MPa. Experiments have been successfully carried out ni with strands made of metal wires having a nominal resistance equal to at 1770 MPa. As visible in figure 2, a network 10 according to the invention is realised developed using a series of strands 1 of figure 1, which are first but folded into a spiral and then wrapped (or “screwed”) together to form links rhomboidal 12. In particular, the rhomboidal meshes 12 are formed im- by tying 12 adjacent strands, which alternately form 180° twists at the points where they cross, so that each strand 1 takes on a zigzag pattern when the network 10 is viewed from the front as in figure 2. Thanks to the flexibility of the strands 1, it is possible to create rom- rather small boidal ones, for example reproducing the dimensions of the ma- commonly used for networks of this type made instead with single wires for use in the geotechnical sector. For example, it is possible to realise to make rhomboid meshes with the dimensions of the diagonals of the rhombuses of approximately 60 x 90 mm to approximately 110 x 180 mm, with an acute angle ε of the mesh rom- boidal which can be between 45° and 55°, preferably between 47° and 54°, more preferably between 48° and 52°, even more preferably between 50° and 51°. The strands 1 of the net 10 may have a protective coating from corrosion. This coating can be made either individually on each wire 2, either - or alternatively - on the already formed strand 1. The coating protection mechanism may be of a generally known type, for example me- thallic, such as an alloy of zinc and aluminum like the one called com- commercially Galfan, or plastic, for example polyethylene, polyvinyl- PROVVISIONATO & CO chloride or polyamide, or a combination thereof. To make the network 10, the strands 1 are used in the machines Notes for the construction of diamond mesh nets. The size of the three- sheets 1, in particular their nominal diameter D, is compatible with the ma- China known because it does not exceed the size of the metal wires used in the construction of the known diamond mesh networks. It has been experimentally found that the initial flattened spiral winding of the strands 1, which preceded of the coupling of the various strands to form the network 10, it is possible without that it is necessary to resort to over-folding or other special procedures, co- but it is described in the known art which uses single metal wires to high resistance. Naturally, without prejudice to the principle of the invention, the forms of at- The situation and the construction details may vary widely. with respect to what is described and illustrated, without thereby departing from the scope of the present invention. PROVVISIONATO & CO

Claims

CLAIMS 1. Diamond mesh netting, in particular for use in civil engineering in geotechnical applications, preferably in the field of protection against natural hazards, the netting being composed of elongated elements which are bent into a flattened spiral and are wrapped around adjacent elongated elements by half a turn, i.e. by 180°, wherein at least some of the elongated elements are ropes or strands each made of at least two metal wires wound helically around the same axis, wherein each metal wire has a diameter of less than 3 mm.

2. Diamond mesh netting according to claim 1, wherein each metal wire of said ropes or strands has a diameter equal to or less than 2.5 mm, very preferably equal to or less than 2 mm, more preferably equal to or less than 1.5 mm, even more preferably equal to or less than 1.1 mm, and can preferably also go below 1 mm.

3. Diamond mesh netting according to claim 1 or claim 2, wherein the metal wires of each rope or strand have the same nominal diameter.

4. A diamond mesh according to any of claims 1 to 3, wherein the metal wires of the elongated elements are made of high-strength steel, with a breaking load greater than 700 MPa, preferably equal to or greater than 1500 MPa, even more preferably equal to or greater than 1700 MPa, even more preferably equal to or greater than 1900 MPa. PROVVISIONATO & CO - 15 PI2948 5. A diamond mesh according to any of the preceding claims, wherein the elongated elements have a nominal diameter of less than 5 mm, preferably equal to or less than 4 mm, more preferably equal to or less than 3 mm, even more preferably equal to or less than 2.50 mm.

6. A diamond mesh net according to any of the preceding claims, wherein the strands or ropes of the net are spiral ropes with a single layer of wires, each comprising at least two metal wires, more preferably at least three metal wires, even more preferably at least five metal wires, even more preferably at least seven metal wires.

7. A diamond mesh net according to any of the preceding claims, wherein the elongated elements have a protective coating.

8. A diamond mesh net according to any of the preceding claims, wherein the metal wires of the elongated elements have a protective coating.

9. A diamond mesh according to any of the preceding claims wherein the meshes have dimensions of the major and minor diagonals of the diamonds between about 60 x 90 mm and about 110 x 180 mm, 10. A diamond mesh net according to any of the preceding claims PROVVISIONATO & CO - 16 PI2948, wherein the acute angle of each diamond mesh is between 45° and 55°, preferably between 47° and 54°, more preferably between 48° and 52°, even more preferably between 50° and 51°.