US20170121919A1

US20170121919A1 - Wire made of high strength steel, particularly for protecting nets for geotechnical use

Info

Publication number: US20170121919A1
Application number: US15/129,546
Authority: US
Inventors: Paolo ORGNONI
Original assignee: GEOPROTECTION Srl
Current assignee: GEOPROTECTION Srl
Priority date: 2014-03-31
Filing date: 2015-03-31
Publication date: 2017-05-04
Also published as: WO2015151025A1; EP3134578A1

Abstract

A wire for geotechnical use is described, for making protecting nets, made of high strength steel. The wire is at least partially shaped in a waveform and has a plurality of crests and valleys arranged alternately one to another. A protecting net is also described, usable in the geotechnical field, having a wire at least partially shaped in a waveform for making the mesh, and/or as a reinforcing element of the net. An anchoring device, a guywire and an energy dissipating device are also described, each having a plurality of wires at least partially shaped in a waveform.

Description

FIELD OF THE INVENTION

The present invention relates to a steel wire used in the geotechnical field for containing masses, such as earth, rock or snow.
It should be immediately noted that the term “geotechnical” herein means the field of the art generally relating to the behavior of soils and its application in constructions and works made thereon.
In particular, the steel wire according to the present invention is used for manufacturing protecting nets and similar containment elements, for making rockfall barriers, snow barriers, for works intended to improve the stability of slopes subjected to landslides, for gabionades, etc.
Furthermore, the steel wire according to the present invention is used for making anchoring devices (also known as tension rods), and in particular passive anchoring devices, used for making foundation works (and therefore for the anchorage to the ground) of containment structures, such as protecting nets, rockfall barriers, snow barriers, etc.
Other uses of the wire according to the present invention are possible, such as for the making guywires and energy dissipating devices, to be used in the geotechnical field, for example as components of containment structures, such as protecting nets, rockfall barriers, snow barriers, etc.

KNOWN BACKGROUND ART

Currently, in the geotechnical field wires are used for making protecting nets, preferably made of steel, having different mechanical characteristics.
Usually steel wires are used having low breaking strength, for example comprised between 350 MPa and 550 MPa. This type of steel is widely used because of its excellent workability and the possibility to easily weld it, due to the low carbon content, thereby allowing to more easily manufacture the nets. In the geotechnical field, the use of high strength steel wires (i.e. having high carbon content) has grown in order to increase the strength, and generally the mechanical responses to both static and dynamic stresses of the protecting nets. For example, this material is used for making simple twist nets (with diamond mesh) as described, for example, in European Patent EP0979329. However, the high strength steel wires give stiffness to the protecting nets in which they are used, thus making them not very adaptable to uneven surfaces. Therefore, the use of high strength steel does not allow to dissipate the desired amount of energy, which is a primary object in manufacturing protecting nets in the geotechnical field.
Moreover, protecting nets are known whose meshes are made of low strength steel and in which additional reinforcing elements, such as additional wires or bars, are constrained to the net. Such a net is marketed, for example, under the trademark Road Mesh®.
As in the case of protecting nets made of high strength steel, the use of reinforcing wires also decreases the adaptability of the net itself to the surfaces on which the net is arranged. In particular, the drawback of the reinforcement elements used in the nets is to give transversal stiffness to the structure.
In fact, although the use of high-strength wires for making the net or the use of reinforcing elements such as additional wires provide an increase of the strength in the plane of the net, this results in a low strength to quasi-static and/or dynamic stresses, very frequent in geotechnical field, acting perpendicular to the surface of the net.
Further, it is known in the art making anchoring device for protecting nets, and similar containment structures, by means of a preferably spiral-like steel rope substantially bent at its center line in a “U” shape so as to form an eyelet, or U-bolt.
The anchoring device is installed in a ground drilling, in which at least part of the two rope branches extending from the bent portion forming the eyelet, is inserted. The anchoring device is made integral with the ground by a suitable binding, e.g. grout, injected into the drilling.
A reinforcing tube and/or a thimble can be provided at the bent portion of the rope of the anchoring device, i.e. at the eyelet, in order to distribute the loads coming from the protecting net and in general from the containment structure connected to the anchorage at the eyelet.
However, the bend of the spiral-like rope at the eyelet reduces the load-bearing capacity of the rope and therefore the breaking strength (the breaking load), in particular when the load acting on the anchoring device operates so as to cause the rope to be deformed at the eyelet provided with the thimble, resulting in an undesired reduction of the curvature radius. As a result, the breaking strength provided by the anchoring device decreases.
The increase of the section (and therefore of the diameter), which generally can range from 14 to 24 mm, of the used spiral rope causes these effects to be enhanced.
In particular, the known anchoring devices have the drawback that the real breaking strength (breaking load) of the anchoring device diverges, even with significant differences, from the theoretical breaking strength defined as the breaking strength of the rope forming the anchorage multiplied by two.
In particular, defining the efficiency of the anchoring device by the relation μ=R_ak/(2*R_fk), where R_akis the value of the breaking load (breaking strength) of the anchoring device and R_fkis the value of the nominal breaking load (breaking strength) of the used rope, the efficiency of the anchoring device is about 0.90 for ropes having a diameter of 14 mm and considerably decreases until about 0.50 for ropes having a diameter of 24 mm.
To overcome these drawbacks, and particularly the decrease in the efficiency of known anchoring devices, caused by the rope deformation at the eyelet and in particular at the thimble, substantially non-deformable thimbles made by melting steel were introduced or reinforcing bushing were provided inside the thimble. However, these solutions cause an increase in complexity in the production and installation of the anchoring device, in addition to an undesirable increase of its weight and respective production costs.
It is an object of the present invention to solve the above briefly discussed problems relating to known protecting nets in the geotechnical field and anchoring devices.
In particular, it is an object of the present invention to provide a corrugated wire for making protecting nets for geotechnical field, which allows the increase of mechanical strength performances and, in particular, a greater amount of energy to be dissipated.
Furthermore, it is an object of the present invention to ensure a high efficiency of the anchoring devices and, therefore, a high breaking strength of the anchoring devices without increasing their weight and cost.

SUMMARY OF THE INVENTION

These and other objects are achieved by a wire usable in the geotechnical field, in particular to be used in manufacturing protecting nets as well as anchoring devices, guywires and energy dissipating devices, according to the present invention.
The wire is made of high strength steel and it is at least partially shaped in a waveform so as to comprise a plurality of crests and valleys arranged alternately one to another.
In other words, the wire according to the present invention comprises at least one portion shaped in a waveform, i.e. a corrugated portion. Preferably, all the length of the wire is shaped in a waveform.
It should be immediately noted that hereinafter the expressions “shaped in a waveform” and “corrugated” mean that the wire is shaped so as to comprise a plurality of crests and valleys alternating to form a wave shape, with respect to the straight, rectilinearly extending wire. In other words, with respect to a straight, or rectilinear, wire, crests and valleys are alternated respectively above and below the straight line along which straight wire extends.
According to an aspect of the present invention, the wire is shaped in a waveform so that the plurality of crests and valleys is contained in a plane. In other words, according to an aspect of the present invention the wire is substantially two-dimensional, that is to say that crests and valleys forming the wave are contained in a plane and do not extend outside that plane.
Advantageously, by using corrugated high strength steel wire, the mechanical performances of the wire are improved, in particular in the elastic field. In particular, a greater wire deformation can be obtained and therefore a greater energy absorption when loads are applied to the wire.
In particular, by using the high strength steel wire at least partially shaped in a waveform, i.e. at least partially corrugated, the wire itself is given a greater elasticity because is straightened, when loaded.
In fact, when loads are applied to the wire, the corrugated shape of the wire tends to deform so as to get the shape of a straight wire, wherein it is substantially rectilinear, thereby allowing a greater work to be performed within the threshold of the elastic behavior limit.
Furthermore, it should be noted that the corrugated wire according to the present invention, when subjected to tensile strength, advantageously allows the formation of a plurality of deformation areas at crests and valleys.
In more detail, the corrugated wire subjected to tensile strength is deformed by reducing its section in a plurality of areas at crests and valleys.
Therefore, advantageously, an elongation occurs in several areas, unlike what occurs in currently used wires (not corrugated, i.e. rectilinear or “straight”) that extend if subjected to tensile stress by producing a single deformation area and, in particular, a single area in which the section is reduced, generally at the position where the tensile breakage will occur.
Advantageously, the corrugated wire according to the present invention consequently allows to perform a greater work, thereby providing increased performances with respect to the rectilinear wire, precisely because of the formation of a plurality of reductions in the section (reductions of the diameter) which cause a plurality of differential elongations acting as a plurality of dissipative elements for the load applied to the wire. The present invention further relates to a cable comprising two or more wires according to the present invention.
The present invention further relates to an anchoring device, a guywire and an energy dissipating device, which comprise a plurality of wires according to the present invention. It should be noted that characteristics/aspects disclosed herein of the wire according to the present invention can be appropriately selected and combined with each other, in particular to modify the corrugated shape, in order to obtain desired characteristics/performances depending on the various uses herein described (e.g. in anchoring devices, guywires, energy dissipating devices, nets, etc.). The present invention further relates to a protecting net that can be used in geotechnical field, for example in rockfall barriers, snow barriers, gabions, etc., comprising the high strength steel wire according to the present invention.
The protecting net can comprise a wire at least partially shaped in a waveform according to the present invention, both for making the mesh of the net, and/or as a reinforcing element of the net. By using the corrugated wire according to the present invention, the net is given a greater elasticity and therefore a greater ability to adapt to uneven surfaces, for example if the net is arranged in contact with the ground or a wall, etc.
Furthermore the protecting net in which, according to an aspect of the present invention, at least 50%, preferably at least 70%, still more preferably at least 90%, or still more preferably 100% is a corrugated wire made of high strength steel, provides a greater deformation of the net if loads caused by falling bodies or masses are applied thereto. Therefore, the net according to the present invention allows a greater amount of energy to be absorbed.

BRIEF DESCRIPTION OF THE FIGURES

Further characteristics and advantages of the present invention will be more evident in the following description, for illustrative purposes referring to the attached figures, wherein:

FIG. 1 shows a portion of a possible embodiment of the corrugated wire according to the present invention;

FIG. 2 shows the section of the wire of FIG. 1 along the plane A-A;

FIG. 3 shows a possible embodiment of a double twist net according to the present invention, wherein the corrugated wire according to the present invention is used as a reinforcing wire;

FIGS. 3a, 3b and 3c respectively show portions of simple twist (diamond mesh) nets, double twist (hexagonal mesh) nets and nets having a plurality of linked rings, whose meshes can be at least partially formed by the corrugated wire according to the present invention;

FIG. 4 is a load-elongation diagram of a tensile test carried out (according to the ETAG 27 guideline) on a triplet of linked rings made of corrugated wire according to the present invention and on a triplet of linked rings formed by a wire having the same mechanical characteristics but being straight (not corrugated);

FIG. 5 is a plan view of a possible embodiment of an anchoring device comprising a plurality of corrugated wires according to the present invention;

FIG. 5a is a sectional view of the anchoring device of FIG. 5 at a spacing element (taken along the plane D-D);

FIG. 6, 6 a respectively show a plan view and a top view of a possible embodiment of an energy dissipating device comprising a plurality of corrugated wires according to the present invention (FIG. 6 shows the enlarged section taken along a plane B-B);

FIG. 7 shows a plan view of a possible embodiment of a guywire comprising a plurality of corrugated wires according to the present invention (FIG. 7 additionally shows the enlarged section taken along the plane C-C).

DETAILED DESCRIPTION OF SOME EMBODIMENTS OF THE PRESENT INVENTION

As shown in figure, the wire 1 for geotechnical use according to the present invention is made of high strength steel and it is at least partially shaped in a waveform so as to comprise a plurality of crests 2 and valleys 3 arranged alternately one to another.
As afore mentioned, partially corrugated means that the wire according to the present invention is generally deformed and therefore shaped so as to comprise an alternation of successive crests and valleys. In the present description, “at least partially shaped in a waveform” and “corrugated” have the same meaning.
In the embodiment shown in FIG. 1, the successive crests 2 and valleys 3 alternating one to another have a substantially rounded shape having a pattern comparable, for the sake of simplicity, to a sine wave.
It should be noted that the wire is shaped in a waveform so that the plurality of crests and valleys substantially lie in a single plane. For example, in FIG. 1 the crests 2 and the valleys 3 of the corrugated wire substantially lie in the same plane which is parallel to, or coincident with, that one of the plate where the wire 1 is shown. The wire 1 can be shaped in a waveform different from the alternation of substantially rounded crests 2 and valleys 3 similar to a sine shape, and can also take the shape of a square, triangle, etc. wave or it can take a fretted shape.
As mentioned, the wire is at least partially corrugated and at least 30% of the wire length is corrugated. Preferably the corrugation with alternating crests 2 and valleys 3 substantially extends to its full length.
Further, according to a preferred embodiment, the waveform is unchanged along the extent of the wire 1. This means that the wire is substantially shaped in the same way along its extent and therefore the shape, as well as the size of the crests 2 and the valleys 3 (preferably in terms of wavelength and wave amplitude), are unchanged along the wire extent.
Preferably the wire according to the invention is made of high strength steel, preferably having a breaking strength (tensile strength) comprised between 1000 MPa (N/mm²) and 2400 MPa (N/mm²).
In particular, according to some possible embodiments, the high strength steel is the same used for manufacturing steel cables according to standard EN10264, or for manufacturing mechanical springs according to standard EN10270.
Furthermore, the elongation at break of the steel wire 1 not shaped in a waveform is equal to, or greater than, 2%. In other words, when the steel wire used to obtain the wire according to the invention in a non-shaped state, i.e. in a straight (rectilinear) state, if subjected to a tensile test its elongation at break is equal to, or greater than, 2%.
Furthermore, the steel wire according to the present invention can be subjected to a surface treatment in order to protect it from oxidation by galvanizing, preferably hot galvanizing, and/or another known treatment adapted to prevent or at least reduce the oxidation. In general, the outer surface can be protected from oxidation preferably by applying a coating comprising zinc during a galvanizing process.
According to an aspect of the present invention, the wire 1 can be subjected to thermal treatments, such as patenting, with the main purpose to provide the material itself with a sufficient workability, for example in order to shape it in a waveform.
As regards the structure of the wire 1 according to the present invention, it is preferably formed as a single wire, i.e. it is not twisted or stranded with other wires.
However, it is also possible that two or more corrugated wires 1, according to the invention, are twisted, stranded or coiled, or subjected to other known processes in order to form a cable after being shaped in a waveform. Alternatively the cable, e.g. a braid or rope, is made with two or more straight wires which are corrugated later.
It should be noted hereinafter that “cable” means a general element, such as a strand, a rope, a braid, etc. comprising two or more wires. Clearly, the wires can be constrained to each other in many ways, for example by coiling, stranding, twisting or other known techniques.
As regards the section S of the wire 1 it is preferably circular, as in the embodiment illustrated in FIGS. 1 and 2. In particular, FIG. 2 shows a view of the section S of the wire 1 of FIG. 1 at the plane A-A.
Preferably, the wire 1 has a section S which is constant along its extent, i.e. the section taken in different positions along its extent remains unchanged.
Nevertheless, it should be noted that according to further possible embodiments, the section S of the wire 1 can take non-circular form and can include, for example, a flat (e.g. rectangular) section, or an oval section, etc.
The diameter D of the circular section S of the wire 1, for example shown in FIG. 2, is comprised between 1.5 mm and 6 mm, preferably between 2 mm and 5 mm, and still more preferably between 3 mm and 4 mm, limits included.
If the section S of the wire is not circular, the above reported size of the diameter D can be referred to the diameter of the circumference circumscribable to the non-circular section of the wire.
Advantageously, by using the wire 1 according to the present invention, made of high strength steel and having at least one portion shaped in a waveform and preferably extending along its entire length, it is possible to increase the wire deformation so as to increase the dissipated energy when a load is applied.
As regards the characteristics of the used waveform and in particular the size of the crests 2 and the valleys 3, the wavelength λ and the wave amplitude y are selected such that the length of the straight wire, i.e. before at least one portion thereof is shaped in a waveform, is equal to, or greater than 3% of the length of the wire 1 after the latter has been at least partially shaped in a waveform.
It should be noted that the wavelength λ is measured between two successive crests 2 and/or successive valleys 3, as shown for example in FIG. 1. The wave amplitude y is measured between a crest 2 and the successive valley 3 (or between a valley 3 and the successive crest 2), as shown for example in FIG. 1.
According to an aspect of the present invention, the wavelength λ between two successive crests 2 and/or two successive valleys 3, is equal to, or greater than 9 mm. According to an aspect of the present invention, the wavelength λ between two successive crests 2 and/or two successive valleys 3, is equal to, or less than 40 mm.
Furthermore, according to an aspect of the present invention, the wave amplitude y between a crest 2 and a valley 3 is equal to, or greater than 2.6 mm. Further, according to an aspect of the present invention, the wave amplitude y between a crest 2 and a valley 3 is equal to, or less than 12 mm. Further, it should be noted that the sizes of the wire waveform can depend on the diameter D of the section of the used wire 1. For example, according to a possible embodiment, for a wire 1, having a diameter equal to 6 mm, a wavelength λ of 40 mm and a wave amplitude y of 12 mm are used.
According to a possible embodiment, for a wire 1 having a diameter D of the section S equal to 2 mm, a wave length λ=9 mm and a wave amplitude y=3.5 mm can be provided. According to a further possible embodiment, using a wire having a diameter D of the section S equal to 3.5 mm, a wave length λ =17 mm and a wave amplitude y=6.2 mm can be provided. By doing so, the length of the straight (rectilinear) wire, i.e. before being shaped, is 1.05 times the length of the wire after it has been at least partially shaped in a waveform, resulting in a difference of 5% between the lengths.
In particular, the Applicant carried out a series of tests on a corrugated wire 1 according to a possible embodiment, having a diameter of 3.5 mm, breaking strength of 1880 MPa, wavelength λ=17 mm and wave amplitude y of about 6 mm, and for example of 6.2 mm, length of the straight wire before being shaped in a waveform of 1050 mm, in order to form a corrugated wire of 1000 mm.
Furthermore, the elongation at break of the straight wire, not shaped in a waveform, is equal to 2.4%.
If a dynamic tensile stress (V=7 m/s) is applied to the above described wire sample, then when the sample breaks the elongation thereof is equal to or greater than 12%, that is about 4% more than the elongation at static breaking stress of the straight, not shaped, wire that is equal to 2.4% and thus equal to 1050 mm (length of the straight wire not shaped in a waveform) ×2.4%=1075 mm.
The elongation measured during the test was equal to 1120 mm, i.e. almost 12%, which is considerably greater than the elongation generated by simply straightening the wire, equal to 501 mm, and than its elongation at break which, as said, is 2.4%.
Advantageously, a greater elongation of the wire allows a greater amount of energy to be dissipated. In particular, during tests carried out by the Applicant, it was possible to verify that the corrugated wire is able to dissipate an amount of kinetic energy equal to approximately five times the amount of the kinetic energy dissipated by a straight wire, i.e. not shaped in a waveform, having the same characteristics.
In fact, when a tensile stress is applied to the wire shaped in a waveform, also as a result of its straightening, that is its deformation to reach the rectilinear state (straight wire), it performs more work, in particular within the elastic limit of the steel, than a wire having the same chemical and mechanical characteristics but without at least one portion shaped in a waveform.
Some tests were carried out by the Applicant also on corrugated wire according to the invention and used to form linked rings, which may be used in a type of protecting nets known in the art (test performed according to the guideline ETAG27, “Guideline for European technical approval of falling rock protection kits”).
In particular, tests were carried out on the above described wire 1, i.e. a corrugated wire having a diameter D of 3.5 mm, breaking strength of 1880 MPa, wavelength λ=17 mm and wave amplitude y=6.2mm, length of the straight (rectilinear) wire of 1050 mm to form a corrugated wire of 1000 mm.
In detail, a triplet of rings (diameter about 350 mm) has been used in which each ring is manufactured with seven windings of corrugated wire 1 and the ends of the corrugated wire constituting the ring are locked by means of a pressed sleeve, or like constraining means.
After a tensile stress has been applied, the triplet of rings is able to resist quasi-static stresses of about 120 kN as a result of a recorded elongation of about 100 mm (the elongation is preferably measured starting at the time in which a load increase is recorded).
Instead, if the tensile stress is applied to a triplet of rings similar to the former, but in which each ring is manufactured with seven windings of the above described wire but not corrugated, i.e. straight, then it is noticed that the triplet resists a quasi-static stress of about 120 kN as a result of a recorded elongation slightly less than 20 mm (as in the preceding case, the elongation is measured starting at the time in which a load increases is recorded).
FIG. 4 compares the load-elongation curve of the triplet of rings made of corrugated wire according to the invention with a load-elongation curve of a triplet of rings made of a wire having the same mechanical characteristics but straight, and therefore not corrugated.
The obtained and compared values highlight that the triplet of rings made of corrugated wire according to the invention has a 400% greater elongation with respect to the one made from not corrugated wire, although they are subjected to the same load. The amounts of energy dissipated by the two triplets are respectively of 9700J (for the corrugated wire) and 1300J (for the straight wire), the difference between the two values being greater than 600%.
Advantageously, during the various tests carried out on triplets of rings made from either corrugated and not corrugated wire, it was found that the corrugated wire, just as a result of the corrugation, is able to almost evenly distribute among all the wires the total force applied during the test, thereby causing a simultaneous breakage of the wires at the connection point with the adjacent ring.
On the other hand, the triplet made from the not corrugated wire was not allowed to benefit from the ability of distributing the stresses among the various wires forming the ring and, as a result, the breakage occurred only on some wires.
The corrugated wire 1 according to the present invention can be used for making nets 10 for geotechnical use.
Furthermore, as above mentioned and as will better seen hereinafter, the wire 1 according to the present invention can also be used for making anchoring devices 50, guywires 60 and energy dissipating devices 70. Additional uses, not described herein, are also possible.
Obviously, even if hereinafter reference will be made to the single wire, the description also relates to the use of a cable according to the invention, comprising two or more wires 1, which can be used for making the mesh of the net and/or for making additional reinforcement elements of the net.
In detail, the corrugated wire 1 according to the invention can be used for making the mesh of the net and/or for making one or more reinforcing wires to be added, and therefore constrained, to the protecting net.
In particular, the protecting net 10 for geotechnical use according to the invention comprises a plurality of wires 11 forming the mesh of the net 10, and at least 50%, preferably at least 70%, still more preferably at least 90%, or still more preferably 100% of the wires forming the mesh of the net are wires 1 made of high strength steel and at least partially shaped in a waveform according to the present invention. This embodiment is not shown in attached figures.
The net 10 according to the present invention can have a diamond mesh (known as single mesh or single twist net), or a hexagonal mesh (for example double twist net), or a mesh comprising a plurality of rings 12 which are linked, or constrained, or connected one to another to form the mesh of the net. FIGS. 3a, 3b and 3c show, respectively, portions of single twist or double twist nets and linked ring nets, although the use of corrugated wire 1 is not shown.
The present invention further relates to a protecting net 10 for geotechnical use comprising a plurality of wires 11 forming the mesh of the net, and at least one additional reinforcing wire 11 a made of high strength steel and having at least one portion shaped in a waveform according to the present invention.
It should be noted that the mesh of the net in which the at least one reinforcing wire 11 a is present, can be made from common straight wires, made of any material, for example also low strength steel. Obviously, also the net comprising a plurality of wires 11 forming the mesh of the net 10 and at least 50%, preferably at least 70%, still more preferably at least 90%, or still more preferably 100% of the wires forming the mesh of the net are wires 1 made of high strength steel and at least partially shaped in a waveform according to the present invention, can be provided with at least one reinforcing wire 11 a made of high strength steel and at least partially shaped in a waveform according to the present invention.
According to an aspect of the present invention, the wires forming the mesh of the net and/or the reinforcing wires of which the net can be provided with, are not welded and, in general, between them movable knots 11 c are formed among the meshes and/or among the meshes and the at least one reinforcing wire, if present.
FIG. 3 shows a possible embodiment of a double twist net 10 wherein the corrugated wire 1 according to the present invention is used as a reinforcing wire 11 a. In detail, among the straight wires 11 forming the double twist mesh of the net, reinforcing wires 11 a are arranged, made from wires 1 according to the invention, and made of high strength steel and corrugated.
In particular, the reinforcing wires 11 a are passed at the sides of the hexagonal mesh where the wires 11 forming the mesh are twisted, so as to cause the movable knots 11 c between the mesh of the net and the at least one reinforcing wire to be formed.
In other words, the mesh and the reinforcing wires 11 a can still move with respect to each other thereby allowing the deformation of the corrugated wire 1 according to the invention of the reinforcing wires 11 a, which deformation allows a greater amount of energy to be dissipated, as previously discussed. Although reference has been made to the possibility of making protecting nets for geotechnical use of single twist, double twist and linked ring type, the steel wire according to the present invention is not intended to be used only in these applications.
Moreover, the wire 1 according to the present invention can be used for making anchoring devices 50.
Preferably, the anchoring device (also known as tension rod) is of passive type and can be either permanent or temporary.
According to an aspect of the present invention, as can be seen for example in FIG. 5, the wires 1 of the anchoring device 50 are bent substantially in a U-shape to form an eyelet 51 (or U-bolt).
It should be noted that “bent substantially in a U-shape” means herein that the wires 1 of the anchoring device 50 are bent to form a central portion, i.e. the eyelet 51, having the two ends of the wire 1 extending from this central portion so as to form two branches 1 a, 1 b of the substantially U shape.
Preferably, the wires 1 are bent at their center line. (i.e. in the middle of their length) so that the two branches 1 a, 1 b have substantially the same length.
It should be noted that, according to possible embodiments of the anchoring device, the wires 1, and in particular the various branches formed as a result of the substantially U-shaped bending, can be arranged in such a way as to be substantially parallel, or they can be wound to each other and, in particular, they can form a braid. In general, according to possible embodiments, the corrugated wires 1 used in the anchoring device 50 according to the present invention, can be twisted, stranded or coiled, or subjected to other known processes.
As can be seen, for example in FIG. 5, according to a possible embodiment, the ends of the wires 1 can be gathered together and connected to each other by means of an end connector 56.
Such connector 56 can be pointy-shaped so as to help the insertion of the anchoring device 50 into the drilling where it has to be installed.
In fact, the anchoring device 50 according to the present invention, can be installed in a ground drilling, in a known way, by inserting therein at least part of the branches 1 a, 1 b extending from the central portion wherein the wires are bent to form the eyelet 51.
Furthermore, the anchoring device is made integral with the ground by a suitable binding injected into the drilling.
Advantageously, the corrugated shape of the wire 1 allows to improve the adhesion of the binder injected into the drilling, thereby significantly improving the grip between the anchoring device and ground.
In order to inject the binding, the anchoring device 50 according to the present invention can be provided with an injection duct (not shown) generally made of plastic material and arranged among the wires 1 of the device, and in particular between the branches 1 a, 1 b of the wires 1.
Advantageously, the anchoring device according to the present invention can be used in the geotechnical field, therefore being able to be installed in the ground, for example to form foundations of protecting nets and in general of containment structures such as rockfall barriers and snow barriers, which can be directly or indirectly connected to the anchoring device 50, preferably at the eyelet 51 formed by the corrugated wires 1 substantially bent in a U shape.
It should be noted that, according to the needs, it is possible to change the number of corrugated wires 1 used to make the anchoring device 50 that is selected in general according to the desired breaking load (breaking strength). For example, in the embodiment shown in FIGS. 5 and 5 a, fifteen corrugated wires 1 have been used, which are bent to form the eyelet 51 and therefore the two branches 1 a, 1 b having in all thirty branches, i.e. twice the number of the wires 1 due to the U-shaped bending.
Advantageously, the use of a plurality of corrugated wires 1 for the realization of the anchoring device allows to maintain a high device efficiency while allowing, at the same time, a reduction of the material (and therefore of its weight).
Experimental tests carried out by the Applicant demonstrated that by using corrugated wire 1 according to the invention for making anchoring devices 50, it is possible to obtain a reduction of the material (and therefore of its weight), preferably between 15% and 40% with respect to the anchoring devices made from spiral rope, with the same characteristics of breaking strength.
Advantageously, by using a plurality of corrugated wires 1 it is also possible to completely eliminate, and in any case to limit, the reduction of the breaking load (and therefore the reduction of the breakage strength) reported in known anchoring devices, caused by the reduction of the curvature radius of the spiral rope at the eyelet (and therefore of the thimble) which tends to deform as a result of the applied load.
In fact, as previously discussed in relation to the wire 1, the corrugated shape provides a greater elongation of wire thereby allowing a greater amount of energy to be dissipated.
Getting back to the anchoring device 50, it is provided with a thimble 53, or a similar element, arranged at the eyelet 51, i.e. at the central portion of the wires 1 bent substantially in a U-shape.
According to an aspect of the present invention, the anchoring device 50 comprises a tubular element 54 and at least part of the length of the plurality of wires 1 is inserted therein and then bent substantially in a U-shape.
In other, words, at least part of the central portion of the wires 1, substantially at the eyelet 51, is inserted in a tubular element 54.
The tubular element 54 is preferably made of steel, preferably galvanized steel. According to a possible embodiment, the anchoring device 50 comprises one or more spacing elements 55 arranged at the branches 1 a, 1 b of the wires 1. According to a possible embodiment, the spacing element 55 comprises a substantially cylindrical body.
The spacing element 55 can be shaped so as to form a plurality of seats 55 a, which are adapted to accommodate at least part of the branches 1 a, 1 b of the wires 1.
According to a possible embodiment, the spacing element 55 comprises a plurality of projecting fins 55 b for the branches 1 a, 1 b of the wires 1 to pass therebetween.
In other words, the wires 1 and in particular the branches 1 a, 1 b are arranged 55 b among the fins 55 b of the spacing element 55. The number of fins 55 b and/or seats 55 a can be set depending on the number of wires 1 used.
According to a possible embodiment, the number of wires 1 and, in particular of the branches 1 a, 1 b, passing between two fins 55 b of a plurality of fins (and/or in each seat 55 b of a plurality of seats) is constant.
In the embodiment shown in the figures (see in particular the sectional view of FIG. 5a ), the spacing element 55 comprises ten seats 55 a, 55 b each formed between two fins, intended to receive each of the three branches of the wires 1. Advantageously, the spacing element 55 allows the wires 1 and in particular the branches 1 a, 1 b to be supported.
The spacing element 55 allows the wires 1 to be inserted effectively into the ground drilling where the anchoring device 50 is installed, in order to perform the proper centering inside it.
The wire 1 according to the present invention can be used for making guywires 60, as shown for example in FIG. 7.
The guywire 60 comprises two or more wires 1 at least partially shaped in a waveform. The wires 1 having the same length are preferably arranged so as to be substantially parallel to each other.
The ends of the wires 1 are constrained together by at least one end connector 61. In other words, the ends of the wires 1 are gathered together and made integral with each other by means of an end connector 61 preferably made of a metal material.
Therefore, the guywire 60 comprises two connectors 61 arranged at the two ends of the wires 1.
It should be noted that the number of corrugated wires 1 used to form the guywire 60 can change according to the needs. In the embodiment shown in FIG. 7 six wires 1 are used.
The guywire 60 according to the present invention can be used in geotechnical field, for example to be directly or indirectly connected to protecting nets and, in general, to containment structures such as rockfall barriers and snow barriers. Such structures can be directly or indirectly connected to the guywire 60 that can be provided with at least one connecting element 62 that can be either constrained to the end connector 61 or made in one piece therewith.
According to a possible embodiment, a shackle 62 is connected to a seat 61 a of the end connector 61.
Although reference has been made to a shackle, clearly other elements 61 to directly or indirectly connect the guywire 60 to a structure (for example to a cable of a structure) can be used, such as rings, U-bolts, etc.
It should also be noted that the end connector 61 itself can act as a connecting element to connect to a structure, for example to a cable of a structure. Advantageously, the corrugated shape of the wire 1 used in the guywire 60 provides a greater elongation of the wire thereby allowing a greater amount of energy to be dissipated.
In particular, the guywire 60 comprising the wire 1 optimizes the strength of the wire 1 and exploits the deformation of its waveform in order to counterbalance the effect of unexpected stresses.
The wire 1 according to the present invention can be used for making energy dissipating devices 70, as shown for example in FIGS. 6, 6 a.
The energy dissipating device 70 comprises one or more wires 1 at least partially shaped in a waveform and preferably forming a closed line. In other words, the used wires 1 have a closed shape, i.e. the two ends of each wire are connected (made integral with each other) to each other so as to form a closed wire 1.
According to an aspect of the present invention, in the energy dissipating device 70, the wires 1 form a preferably and substantially circular, or oval, or elongated closed line.
In other words, the wires 1 form a ring that can be substantially circular (as shown for example in the attached figures), or can have an elongated and/or flattened shape.
It should be noted that the number of corrugated wires 1 used to form the energy dissipating device 70, can change according to the needs. In the embodiment shown in FIGS. 6, 6 a three wires 1 are used.
The energy dissipating device 70 according to the present invention can be used in geotechnical field, for example to be directly or indirectly connected to protecting nets and, in general, to containment structures such as rockfall barriers and snow barriers.
Such structures can be directly or indirectly connected to the energy dissipating device 70 that can be provided with at least one connecting element 71 that can be either constrained to one or more wires 1 or made in one piece therewith.
According to a possible embodiment, such as shown in FIGS. 6, 6 a, two shackles 71 are connected to the wires 1 in order to allow, for example, a structure (not shown) to be connected to cables.
Although reference has been made to a shackle, clearly other connecting elements 71 to directly or indirectly connect the energy dissipating device 70, and in particular the wires 1, to a structure (for example to a cable of a structure) can be used, such as rings, U-bolts, etc.
Advantageously, as previously discussed in relation to the wire 1, the corrugated shape provides a greater elongation of the wire thereby allowing a greater amount of energy to be dissipated.
In detail, the energy dissipating device 70 exploits the characteristics of the corrugated wire 1 according to the present invention and, in particular, its improved deforming characteristics to obtain a greater energy dissipation.
It should also be noted that a manufacturing method comprising the shaping of a high strength steel “straight” wire, so as to form at least one portion shaped in a waveform, allows an easy and cost-effective production of the wire 1. In particular, the method can comprise the step of putting the wire in contact with, and/or passing the wire through, deforming means able to obtain the waveform. For example, the wire deforming means can comprise at least one, and preferably at least a pair of toothed wheels, generally shaped so as to form crests and valleys of the waveform of the wire.
The wire is moved in contact with the wheel, or wheels, or similar deforming means in order to cause its deformation and thus the at least partial shaping thereof in a waveform.
The method is such that the corrugated wire 1 takes the shape and size (preferably in terms of wavelength and wave amplitude) described above.

Claims

1. Wire for geotechnical use, particularly for making protecting nets, said wire being made of high strength steel and wherein it is at least partially shaped in a waveform and comprising a plurality of crests and valleys arranged alternately one to another.

2. Wire according to claim 1, wherein it is shaped in a waveform in all its length.

3. Wire according to claim 1, wherein said waveform is unchanged along the wire extent.

4. Wire according to claim 1, wherein it has a breaking strength comprised of between 1000 MPa and 2400 MPa.

5. Wire according to claim 1, wherein is has an elongation at break, when said wire is not shaped in a waveform, equal to or greater than 2%.

6. Wire according to claim 1, wherein it has a circular section (S).

7. Wire according to claim 1, wherein the diameter (D) of said circular section (S), or the diameter of the circumference circumscribable to the non-circular section (S) of the wire, is between 1.5 mm and 6 mm limits included.

8. Wire according to claim 1, wherein the wavelength (λ) between two successive crests and/or between two successive valleys and the wave amplitude (y) between a crest and a valley are selected so that the wire length before it is shaped is equal to, or greater than, 3% of the length of the wire shaped in a waveform.

9. Wire according to claim 1, wherein the wavelength (λ) between two successive crests and/or two successive valley is between 9 mm and 40 mm.

10. Wire according to claim 1, wherein the wave amplitude (y) between a crest and a valley is between 2.6 mm and 12 mm.

11. Wire according to claim 1, wherein it is at least partially shaped in a waveform for at least 30% of its own length.

12. Wire according to claim 1, wherein said plurality of crests and valleys is contained in a plane.

13. Cable comprising two or more wires at least partially shaped in a waveform according to claim 1, wherein said wires are twisted, stranded or coiled, before or after said wires have been partially shaped in a waveform.

14. Protecting net for geotechnical use comprising a plurality of wires forming the mesh of said net, wherein at least 50%, of said wires forming the mesh of said net are wires made of high strength steel and at least partially shaped in a waveform according to claim 1.

15. Net according to claim 14, wherein said wires form a single mesh, or a double twist mesh, or a plurality of rings which are linked, or constrained, or connected one to another, to form the mesh of said net.

16. Protecting net for geotechnical use comprising a plurality of wires forming the mesh of said net, further comprising at least one more reinforcing wire, said at least one reinforcing wire being a wire made of high strength steel and at least partially shaped in a waveform according to claim 1.

17. Anchoring device for geotechnical use comprising two or more wires at least partially shaped in a waveform according to claim 1.

18. Anchoring device according to claim 17, wherein said wires are bent substantially in a “U” shape thereby forming an eyelet and two branches of said wires.

19. Anchoring device according to claim 17, further comprising at least one thimble.

20. Anchoring device according to claim 17, further comprising at least one tubular element in which the plurality of wires is inserted.

21. Guywire for geotechnical use comprising two or more wires at least partially shaped in a waveform according to claim 1.

22. Guywire according to claim 21, wherein the ends of said wires are constrained one another by means of at least one end connector.

23. Energy dissipating device for geotechnical use comprising two or more wires at least partially shaped in a waveform according to claim 1.

24. Energy dissipating device according to claim 23, wherein said wires form a closed line.

25. Energy dissipating device according to claim 23, wherein said wires form a substantially circular, or substantially oval, or substantially elongated closed line.