Protective structure and metal protection net for such a protective structure

Abstract

The present application relates to a protective structure for civil engineering comprising at least one metal protective net comprising a plurality of elongated resistance elements in the form of wires, ropes or cables, wherein at least some of the plurality of elongated resistance elements are made of a material having super-elastic properties.

Description

Technical Field

[0001] This invention relates to the field of structures for protecting against geologically unstable events such as rockfalls, avalanches, or debris flows.

[0002] This invention is specifically developed for protective structures comprising at least one metal protective mesh. Background Technology

[0003] In mountainous areas, structures are known to be provided for protection against geologically or hydrogeologically unstable events in which materials (e.g., rocks, stones, debris, or snow) are unexpectedly moved from an upstream area to a downstream area due to natural and unpredictable causes such as landslides, avalanches, or debris flows. These protective structures typically include at least one metal mesh that prevents or delays the movement of materials in the downstream direction.

[0004] Protection against rockfalls or debris flows is a critical factor in the safety and resilience of infrastructure, buildings, goods, and people. Even the smallest landslides or debris flows can cause severe damage and disruption, resulting in significant economic losses. The same applies to the destructive and adverse effects of avalanches that can occur in snow-covered mountainous areas.

[0005] In recent years, public administration agencies have paid increasing attention to rockfall incidents, characterized by rocks with a size of 0.02m. 3 up to 5m 3 The stones detached at speeds reaching and sometimes exceeding 30 m / s and subsequently moved downstream, causing serious damage to the underlying structures. This incident also raises concerns about the public safety of all structures, buildings, and connections located within the area of ​​concern affected by these incidents.

[0006] In the past, interventions involving passive protection against falling rocks mainly consisted of special rigid barriers made of metal plates, which were not very flexible structures. These structures left the function of dissipating impact energy to the materials that made the structure with rigid elements made of steel by intercepting and retaining rocks.

[0007] Recently, more flexible barriers made of metal mesh and connected with ropes where applicable have become increasingly common. These systems, suitable for installation on potentially unstable slopes, are used to intercept and block falling rocks via a metal mesh that allows the impact force to be transferred to the base structure through a complex system of cables and other connecting elements. However, such structures require frequent maintenance and may require replacement of components deformed after a rockfall, potentially leading to the accumulation of irreversible plastic deformation in some parts of the structure. Furthermore, it should be noted that, in its current state, testing of these structures will rely on full-scale impact testing, essential for assessing the true effectiveness of each type of barrier. These tests are extremely difficult in terms of both time and cost.

[0008] In situations involving the hazard of falling rocks, it is advantageous to install rock-holding caps or surface stabilization nets. These protective structures consist of a net fixed to the surface of a rock slope so that any rock detached from the wall can fall to the bottom of the slope while always remaining contained between the rock and the cap net. Examples of such protective structures are described in WO 2005 / 038143 and WO 2011 / 030316 from the same applicant.

[0009] In other rockfall hazards, installing rock-retaining mulch or surface stabilization nets is not advantageous due to technical, terrain, economic, or proximity issues. In these cases, effective solutions include installing rock-retaining barriers along the rock face or at the base of the slope, depending on available space. These barriers are designed to intercept and block falling rocks and stones, thereby dissipating the energy transferred upon impact through plastic deformation of some components of the structure.

[0010] The fundamental features of a rock-holding barrier lie in its interception structure (net), support structure (posts and support ropes), and braking system. This braking system consists of sacrificial elements, so-called brakes or dissipators, which extend to dissipate the introduced energy. Currently used energy dissipation systems are typically based on the plasticization of metals (aluminum, steel) or friction between contact surfaces. However, it is clear that after an impact from a rock with energy comparable to the projected energy, permanent deformation will be recorded in the structure (which limits its performance level) because the structure cannot withstand further deformation under subsequent impacts until elements are provided to replace the deformed elements, thus restoring the initial geometry before the impact.

[0011] The performance level of a rock retention barrier is typically expressed in terms of the barrier’s interception energy and interception height, which is understood as the minimum distance between the lower and upper ropes of the barrier.

[0012] Standard ETAG 0271 defines two distinct performance levels for certifying rock-holding barriers. The first level, called MEL (Maximum Energy Level), enables the barrier to intercept and block material impacting it at its maximum energy level (100%) with a residual height >50% of the initial height. The second performance level, called SEL (Service Energy Level), enables the barrier to intercept and block two consecutive materials (without any maintenance) impacting it at an energy level equal to 30% of the MEL. In this case, the residual height must be >70% of the initial height.

[0013] Given the significant reduction in the barrier's remaining height (of a given magnitude downstream of the event), special maintenance operations must be performed to replace the brakes and any other damaged components, restoring the barrier's original geometry. All of this involves high administrative costs, especially considering that rock-holding barriers are typically installed on rock slopes, often in remote and inaccessible locations.

[0014] Examples of rock-holding barriers are described in the same applicant's EP 0940503. There are also known barriers for protecting against debris (mud and water matrix or rock matrix) falling due to flooding; these can be installed on slopes (open slopes as well as in valleys and canyons), and they may or may not use posts depending on their shape. Examples of such barriers are described in WO 2014 / 141096 from the same applicant.

[0015] One of the biggest drawbacks of these known types of protective structures is the need for complete or partial replacement after the structure has been subjected to an impact of significant magnitude. Replacement may involve the metal mesh or its anchoring components, or, in the case of a barrier, the support ropes or struts of the mesh or dissipative elements. Due to the location of the protective structure (which is typically installed on steep slopes, inaccessible inclines, or difficult-to-access isolation zones), these maintenance operations are expensive and often very difficult.

[0016] Therefore, it is recognized in the art that there is a need for improved solutions regarding the performance level of protective structures that reduce the need and frequency of replacement, repair, or maintenance, and that enable efficient and long-term use even after one or more operations for protection against impact events. Summary of the Invention

[0017] The purpose of this invention is to provide a protective structure and / or a metal protective mesh used in a protective structure, such as a rock-holding barrier or control barrier for debris flows, that overcomes the shortcomings of the prior art. Another purpose of this invention is to improve the performance level of protective structures (e.g., rock-holding barriers). Another purpose is to provide a protective structure and / or a metal protective mesh that maintains its individual blocking characteristics even after being subjected to significant and repeated impacts from materials such as rocks, debris, snow, etc. Another purpose of this invention is to improve the performance level of protective structures (e.g., rock-holding barriers). Another purpose is to provide a protective structure and / or a metal protective mesh that maintains its individual blocking characteristics even after being subjected to significant and repeated impacts from materials such as rocks, debris, snow, etc. Another purpose is to provide a protective structure, protective mesh, and / or metal protective mesh that is economical and durable over time, and capable of reducing maintenance costs.

[0018] Of the aforementioned objectives, a specific objective is to provide a protective structure, such as a rock-holding barrier, in which the structure is guaranteed to recenter, that is, after a collision or impact has ended and once the load has been removed, the protective structure returns to its pre-existing state, and further, plasticization is generated concentrated in the net and confined to a few restricted areas. Another specific objective is to prevent replacement of dissipators or brakes in the rock-holding barrier (provided together with the rock-holding barrier) and to prevent repositioning of the structure after an impact with high internal energy (comparable to the planned internal energy).

[0019] These and other objectives are achieved by protective structures and / or protective nets having the features indicated in the appended claims.

[0020] This invention is based on the principle that, according to so-called smart materials such as shape memory alloys, the kinetic energy of rock is converted into deformation energy in multiple components of a protective structure (particularly the protective mesh or its parts and / or the support components or its parts). Such materials are typically referred to using the acronym SMA (shape memory alloy) and are characterized by reversible elongation when deformation occurs within the typical elastic range of these metallic alloys (e.g., but not limited, approximately 8% to 10%). In the applicant's innovative use, this material is used in protective structures to withstand elastic deformation, thereby dissipating energy and limiting the force transmitted to anchoring components. When the impact load is removed, the components made of SMA-type alloys re-emerge with their initial geometry, thus at least partially eliminating the generated deformation. Therefore, this innovative approach has significant advantages. First, without any replacement of deformation-dissipating components, the protective structure is guaranteed to return to its initial configuration once the load is removed. This therefore involves reduced maintenance costs during use.

[0021] The originality of this invention is evidenced by the lack of research and / or publications regarding the possibility of using the properties of SMA materials to improve current protective structures (e.g., rock-holding barriers). Therefore, this invention is designed to be significantly innovative relative to current prior art because, in addition to guaranteeing the aforementioned technical and economic advantages, it introduces highly innovative elements capable of solving typical problems of existing standard solutions.

[0022] The protective structures involved in this invention may include (but are not limited to) rock-retaining barriers, snow-retaining barriers, hybrid rock-retaining barriers, snow catchers or reinforced catchers, nets for cortical reinforcement, nets for preventing debris from falling, and other structures of this type. Examples of structures and / or protective nets that can be modified to be included in or to incorporate elements of the invention are described in WO 2005 / 038143, WO 2011 / 030316, WO 2018 / 146516, WO 2014 / 141096, and WO 2021 / 053592, which are incorporated herein by reference. Attached Figure Description

[0023] Further features and advantages will be understood from the following detailed description of preferred embodiments with reference to the accompanying drawings, which are given by way of non-limiting example, and in which:

[0024] - Figure 1 This is a perspective view of a protective structure in the form of a rock-forming barrier, incorporating aspects of the present invention;

[0025] - Figure 2 It is used with Figure 1 Perspective views of different embodiments of support ropes for protective structures with similar structures;

[0026] - Figure 3 It indicates Figure 2 Details of the support rope, which is in a non-load-bearing construction, wherein the hyperelastic material element is in an unloaded and undeformed state; and

[0027] - Figure 4 It indicates Figure 3 The same details are in a structure subjected to load, in which the hyperelastic material element is under load with maximum deformation. Detailed Implementation

[0028] Now for reference Figure 1The rockfall prevention barrier 10 (also known as a rock-holding barrier) comprises a mesh panel 12 supported by posts 14 fixed to the ground. A series of ropes 16a support the mesh 12 continuously at the top, preferably passing through the upper ends of the posts 14. One or more ropes 16b are connected longitudinally to the lower ends of the mesh 12, preferably passing through the base of the posts 14. Ropes 16a and 16b are secured to anchoring members 18, which are fixed to the ground. The posts 14 are also preferably connected to other anchoring members 18 upstream of the barrier via ropes 19. In the illustrated embodiment, the barrier 10 does not have brakes or dissipators along the ropes 16a, 16b, and 19. The mesh panel 12 is preferably constructed with a protective net, which is of the type having loops or panels made of ropes, and may be fitted with a metal mesh having double or single twists.

[0029] One or more components of the protective barrier 10 (e.g., all or some of ropes 16a, 16b, or 19) are made of a material with superelastic properties, whose main characteristics include the inherent ability to withstand large elastic deformation (approximately 8% to 10%), to recover the initial structure by removing the load state (i.e., by removing the rock affecting the work), and without any substantial residual deformation. More specifically, one or more metal alloys with superelastic properties can be used, such as, but not limited to, copper / zinc / aluminum Cu-Zn-Al, copper / aluminum / nickel Cu-Al-Ni, iron / manganese / silicon Fe-Mn-Si, and titanium / nickel Ti-Ni metal alloys, such as alloys with 55.9% Ni and 44.1% Ti, commercially known as nitinol, which have good superelastic properties, that is, the ability to absorb greater elastic deformation energy and high hysteresis to generate greater dissipation capacity. These alloys are also selected for their excellent fatigue resistance and corrosion resistance, which makes them particularly suitable for efficient use in applications with direct contact with the external environment and for the protective structures of the present invention.

[0030] As described above, the material with superelastic properties is formed from wires, cables, or ropes, which are braided, interwoven, or connected to the protective mesh of the protective structure in any case. For example, it can be constructed using ropes or wires or braking elements made entirely or partially of SMA materials (such as Nitinol); thus, after the impact load is removed, the elastic elongation caused by the block impact will be restored, and the rope will return to its initial structure before the impact, such as... Figure 1 As shown.

[0031] Therefore, the barrier retains its initial geometry, particularly the interception height, without replacing any components. All of this represents a significant reduction in maintenance costs, thereby ensuring the continued level of security provided by the barrier.

[0032] The restoration of this initial state can be limited to an energy level corresponding to the performance level denoted as SEL (Working Energy Level), or can reach a level denoted as MEL (Maximum Energy Level): reaching both limits can be achieved by the dimensions of ropes 16a and / or 16b and / or 19 made of SMA alloy, or by combining conventional dissipative elements with ropes 16a and / or 16b and / or 19 made of SMA alloy.

[0033] In addition to ropes made of SMA material, or alternatively, one or more loops made of SMA-type alloy wire can be interwoven in the mesh panel 12. The protective structure can also be reinforced using rods or other elongated elements of SMA material, which are stacked on or interwoven with the protective net. For example, a protective net with a mesh panel constructed from a double-twist type net can be constructed, having one or more elastic reinforcing elements interwoven with the net, inserted into its mesh, and / or combined in one or more double-twist nodes made of SMA material.

[0034] Figure 2 A specific embodiment of the support rope 20 is shown, which is adapted to support the protective structure 10, which is similar to... Figure 1 The protective structure shown, or more generally a protective structure comprising a net supported by posts, such as a hybrid protective structure, wherein the net is supported by posts at the top and is free at the bottom.

[0035] exist Figure 2 In the example, rope 20 is formed by two rope portions 20a and 20b, which are connected to each other in the area of ​​a dissipator or brake 21 of a type commonly known in the field of protective structures. As will become clearer below, the presence of the dissipator or brake 21 is not essential to the purpose of the invention, and rope 20 can be provided without it, thus allowing it to be constructed as a single piece. Moreover, rope 20 does not necessarily have to be manufactured from only one or two pieces, but can also be constructed by connecting multiple pieces, segments, or sections of rope together in series and / or in parallel. Preferably, rope 20 is a metal rope made of steel.

[0036] Rope 20 is secured to the ground by anchoring member 18. At the other end, rope structure 20 is secured to the upper end 21 of post 14. According to various techniques known in the art, the type in which rope 20 is secured to the ground and post 14 at its two ends can be different from the type shown.

[0037] When the dissipator or brake 21 is mounted on the rope 20, it is suitable for absorbing the impact energy of, for example, a landslide (which includes a protective structure). The dissipator or brake 21 shown comprises two metal tubes 22 arranged side-by-side, with two corresponding rope portions 20a, 20b extending within these tubes, the ends of which protrude from opposite sides of the dissipator or brake 21. Two compression heads 23, positioned at the ends of the metal tubes 22, also pass through the rope portions 20a, 20b, with ends 24 secured to the ends of these rope portions 20a, 20b.

[0038] The traction force on the rope sections 20a and 20b pushes the terminal 24 against the compression head 23, which in turn presses against the tube 22, causing the tube 22 to plastically deform when the traction force is large enough. This deformation of the tube 22 absorbs and dissipates the high impact energy acting on the protective structure.

[0039] A damping member 25 is also provided on the rope 20, which elastically responds to the traction stress on the rope 20 up to a given magnitude (due to impacts with relatively small energy). Additionally, a dissipator or brake 21 can function. The damping member 25 includes an elastic segment 26 positioned between two fixed locations 28 on the rope 20. The fixed locations 28 can be constructed by two metal sleeves coiled on the rope 20 or by a connecting device of a similar functional type. The elastic segment 26 can be constructed from one or more rope sections of a material with hyperelastic properties (e.g., nitinol of the type described above), which are arranged in series and / or parallel relative to each other.

[0040] from Figure 3 It can also be seen that, in the non-deformable structure, the elastic segment 26 has a length L1 between the two fixed positions 28 on the rope 20. This length L1 is determined based on the material of the elastic segment 26 and the characteristics of the protective structure. For example, the length L1 of the elastic segment 26 between the fixed positions 28 can be approximately 1 m, although it is not excluded that it can be less or greater than 1 m. The two ends 29 ensure that the elastic segment 26 will not wear or detach from the fixed positions 28 when subjected to traction.

[0041] The rope 20 has a resistance portion 30 between two fixed positions 28, the length L2 of which is greater than the undeformed length L1 of the elastic segment 26. Preferably, the length L2 is less than this length plus the length of the elastic segment 26 that will undergo permanent plastic deformation. Typically, the length L2 is about 8% to 10% greater than L1, which means that for an elastic segment 26 with a length L1 equal to 1 m, the resistance portion 30 has a length L2 of about 1.08 to 1.10 m.

[0042] In the non-deformable structure of the elastic segment 26, when the rope 20 is not subjected to any traction force, the resistance portion 30 between the fixed positions 28 remains slack, such as... Figure 2 and Figure 3 As shown. Figure 4 This illustrates the limiting condition where rope 20 is subjected to a traction force such that the elastic segment 26 experiences its maximum predetermined elongation, at which its deformation remains within the hyperelastic range. When this limit is reached, the resistance portion 30 of the rope tightens. As the traction force on rope 20 increases, the load is supported by the resistance portion 30, thereby preventing plastic deformation of the elastic segment 26. When the load on rope 20 is removed, the elastic segment 26 elastically returns to its initial state. When the traction force is not too high, rope 20 returns to its previous state, ready for new intervention without requiring replacement of any parts. When the traction force on rope 20 must be very high, upon reaching... Figure 4 After the extreme state shown, the dissipator or brake 21 (if present) begins to operate, wherein the deformation of the metal tube 22, as is known, plays a role in absorbing the impact energy acting on the protective structure.

[0043] although Figure 2 The diagram shows a rope 19 supporting the column 14, but the formation of this rope, equipped with a damper 25, can also be reused for one or more other supporting ropes of the protective structure, that is, rope 16a supporting the top of the net 12 in a continuous manner or rope 16b connected to the lower end of the net 12 in a longitudinally continuous manner. Of course, while the principles of the invention remain unchanged, the form and construction details of the embodiments can be varied extensively with respect to what is described and shown, without departing from the scope of the invention.

Claims

1. A protective structure for civil engineering projects, the protective structure comprising: At least one metal protective net, the metal protective net comprising a plurality of elongated resistance elements, the elongated resistance elements being in the form of wires, ropes or cables; Among these, only some of the multiple slender resistance elements are made of a material with superelastic properties; At least one of the plurality of elongated resistance elements in the form of wires, ropes or cables includes an elastic segment made of a material with superelastic properties; A resistance portion of a wire, rope, or cable, which is initially arranged loosely and adjacent to an elastic segment, is taut while the elastic segment extends until the extension of the elastic segment ends at a predetermined limit less than the plastic deformation of the elastic segment. The elastic segment has a first length between two fixed positions, and the resistance portion has a second length between the two fixed positions, the second length being greater than the undeformed length of the elastic segment.

2. The protective structure according to claim 1, wherein: Slender resistance elements with superelastic properties are the parts of cables or ropes used to anchor protective structures to the ground.

3. The protective structure according to claim 1, wherein: Materials with superelastic properties are selected from the group consisting of copper / zinc / aluminum (Cu-Zn-Al) metal alloys, copper / aluminum / nickel (Cu-Al-Ni) metal alloys, iron / manganese / silicon (Fe-Mn-Si) metal alloys, and titanium / nickel (Ti-Ni) metal alloys.

4. The protective structure according to claim 3, wherein: The material with superelastic properties is an alloy containing 55.9% Ni and 44.1% Ti.

5. The protective structure according to claim 1, wherein: The second length is limited to the elastic segment of a wire, rope, or cable made of a material with superelastic properties, which is approximately 8% to 10% greater than the undeformed length of the material with superelastic properties.

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