SUPPORT STRUCTURE FOR A DYNAMIC ROCKFALL BARRIER

Abstract

 The invention relates to a support structure suitable to be used within a dynamic rockfall barrier, the barrier comprising interception means (2) receiving the impact from occasional or frequent rockfall, shallow landslide or debris flow. The barriers deforms and transmits the stress to the ground whereby a plurality of cables (5) supporting the interception means (2) and transmitting the stresses generated onto the interception means (2) to the ground are used.
The claimed support structure comprises a plurality of posts (3) each one directly fixed to the ground by means of a single anchorage bar (4) arranged aligned. The posts (3) have a tubular shape and are joined to the anchorage bars (4) uniquely by a connecting element (7) and a fastener (6) passing through one or more drills (7b) in the connecting element (7) and one or more drills (3a) in the post (3).
The invention further relates to a falling rock barrier (1) structure comprising a support structure as the one described.

Description

Field of the invention

[0001] The present invention relates to a support structure used in a protective structure against the fall of rocks, more particularly of the dynamic rockfall barrier type.

Background of the invention

[0002] Roads, railroads and all types of buildings and other structures are often exposed to rockfall and thus need to be protected: rockfall can be occasioned by works, natural phenomena or natural causes, and can produce severe damages to people, buildings and infrastructures, with severe economic or social consequences.

[0003] In mountainous regions, the use of different types of protecting barriers for shielding and protecting installations or infrastructures from rockfall is widespread. Different types of protecting systems are known to respond to the different problems associated with instability of rock faces or slopes. In cases where, due to technical or economic reasons, a definitive solution for the stabilization of slopes is not possible, the so-called "passive protective" structures against rockfall are used, such as rockfall fences or embankments, which act as barriers to intercept, capture or divert falling rocks preventing them from impacting a critical infrastructure or persons. Dynamic rockfall barriers are one of the most commonly used passive-protective systems.

[0004] The operating principle of a dynamic rockfall barrier relies on the impact absorption by means of the progressive dissipation of the kinetic energy of the impact, which is converted into braking energy. These dynamic rockfall barriers typically comprise at least a net made of wires or steel cables, mounted with cables onto a support structure (typically metallic posts) that is articulated on its base and anchored into the ground. Falling rocks are stopped by energy dissipating elements, such as nets, cables typically provided with braking means and anchorages. Thanks to the deformation characteristics of these elements, the system can withstand a high impact energy. During the impact, the system ensures that the energy from the falling rocks is dissipated.

[0005] The first cable net is known in the 1950's, first to protect against snow avalanches, later to stop rockfall. These systems were made by nets of cables, intertwined and stapled among them, configuring a surface of a panel-type, supporting the impact of a falling rock. These primitive nets removed the stiffness of the existing rigid barriers at the time, that were made of concrete, wood or steel and that absorbed the impacts in a stiff manner and without any flexibility, originating often failures, even when subjected only to low energy impacts. With the concept of flexibility, dynamic barriers have been originated.

[0006] New types of more resistant and flexible nets and also new types of anchorages were designed in the years following the 1950's: also, braking means started to be added to the cables connecting the nets and the support structure with the anchorages. These braking means allowed increasing the braking distance and consequently allowed the absorption of higher kinetic energy. The braking means turned into the differentiating element of each manufacturer.

[0007] From the 1990's the design of dynamic barriers turned professional under tests carried out at real conditions, typically in quarries. Under this methodology, the elements in the dynamic barriers were optimized and so the energy absorption ability was verified and improved. The method for measuring energetic strengths was also made professional and tests were even represented using finite elements programs. The development was frenetic during some years and the absorption ability was gradually increased from 500 KJ to 10.000 KJ.

[0008] At present, functionalities of this type of barriers are certified according to the guideline ETAG 027 "Guideline for European Technical Approval of falling rock protection kits". This guideline sets standardized test procedures to determine, departing from the kinetic energy of a regular block impacting a considered net fence, certain parameters such as nominal height and commercial height, downhill displacement, braking time, residual height, etc. which would permit adjusting the dimensions of the barrier to the area that needs to be protected.

[0009] However, this increasing competitiveness towards higher energies in laboratory conditions (according to ETAG027) has not been accompanied by the development of the reliability in usage conditions in real practice. The different manufacturers of this type of products have focused on the development of more elastic and more resistant nets, on better braking means, etc. always with the aim of increasing impact absorption, therefore always looking for products allowing the absorption of more and more KJ. No attention has been given to other issues not present in the certification guidelines. For example, a barrier of 5000 KJ can be severely damaged or reduce the protection height with an impact to one of its posts (support structure) or into a border panel of only 500 KJ. Rockfall events in different countries and circumstances confirm this fact. This circumstance is not even contemplated by ETAG027, always considering the supposition of the rock impacting in the center of the net arranged between two supporting posts.

[0010] Besides, it is important to consider that not all mountainous areas or regions have the same geological or geotechnical conditions. For example in the Alps, rockfall is a very sporadic phenomenon, but usually with big blocks and high energies. Rockfall protection systems are installed where maybe only one or no event of rockfall occurs in a lifespan of the described system. On the other hand, in the Andes or the Iberian Peninsula, rockfall is frequent due to more fractured rock formations, thus rockfall protections should offer higher stiffness and less deformation on impacts and less maintenance needs. In the Andes, the protection against frequent rockfall on hundreds or even thousands of kilometers of roads and railroads cannot be solved by highly flexible and costly protection systems of high energy, because it is simply unaffordable for these countries.

[0011] The support structure of the present invention is applied to this type of barriers that could be named as semi-dynamic, protecting structures against having limited flexibility, high reliability, as well as easy, fast and reliable assembly, and with market prices which are lower than those for the full or hyper dynamic barriers. For this, and more specifically, the present invention develops several improvements in the support structures of the above-mentioned barriers.

[0012] As it has been mentioned, the installation of flexible metallic barriers is known in the state of the art as the most effective solution against rockfall. These barriers are usually installed in mountainous areas, particularly in slope areas located either in structures or buildings or in infrastructures such as roads or railroads, with the object of avoiding that a sporadic rockfall could cause damages or accidents on the mentioned structures that are arranged below.

[0013] Among many others, patents EP 1205603 B1 or US 5435524 can be mentioned. Both documents disclose a dynamic barrier system comprising, basically, an intercepting structure comprising a metallic net more or less dense, a support structure comprising several posts, anchored in an articulated manner to the soil and to which the net is fixed, and several connecting components comprising steel cables fixing the top ends of the posts, as well as a set of anchoring elements. At least a braking means is integrated in the respective connecting components: in the case of a fall of a rock or a similar element, the braking means proportionally absorb traction energies or other energies appearing in the net. This type of braking means are typically shaped as a U or as a ring and comprise, for example, a curved metallic tube (metallic bar), joined on one end with a string to the support or post and, on the other end, joined with a string to the net. Another example of support structure is described in EP 2268867 A1, for example, disclosing a cable guide for moveable cables used in rockfall barriers joined to a supporting post by means of a running roller and joint halves, which presents a complicated structure.

[0014] As it has been described, these types of support structures are complex and require multiple components sensitive to suffer damage on direct impacts, so there exists the need to provide more simple support structures able to provide the same functionalities. The present invention comes to solve these needs.

[0015] Moreover, the effectiveness of this type of barriers is highly dependent on the different types of braking means and on the type of nets used. However, very little or no attention is given to the support structures. The sections generally used at present are metallic profiles HEB and HEA: these posts present very low stiffness and, when hit by a rock, they bend easily. Furthermore, HEB and HEA posts present limited resistance on compression, as a rockfall impact generates high compressive forces through upper and lower cables onto the posts. As already described, ETAG 027 guideline considers the posts as simple "holding elements" of the nets, being these nets and brakes, the key elements that are in fact tested and certified as to their absorption ability: however, in the tests effected according to the mentioned guideline, it is not considered that the rock may hit the post.

[0016] The present invention comes to provide a solution to this need, providing a reliable support structure for a rockfall barrier that is also able to withstand and effectively absorb rock impacts occurring on the post itself.

[0017] Thus, the present invention aims at providing a support structure that improves and simplifies the existing support structures known in the state of the art. The invention also aims at other objects and particularly at the solution of other problems as will appear in the rest of the present description.

Summary of the invention

[0018] The present invention refers to a support structure for a barrier for protection against the fall of rocks: this barrier will be typically installed in slopes or vertical locations in mountainous environments, as a retention element for rocks avoiding they fall and impact on structures or infrastructures arranged below. The support structure of the invention and the final barrier so configured presents several advantages with respect to the barriers in the known prior art: the constructive and configuration characteristics provide higher effectiveness and optimized manufacturing costs.

[0019] As already discussed, dynamic or flexible barriers are used to minimize damages coming from natural disasters such as from the falling of rocks, blocks, stones, including landslides or debris flow where water is an important element. As these barriers have the ability of absorbing high energy without being damaged, thanks to their flexible structural configuration intercepting rockfall, shallow landslides or debris flow.

[0020] A rockfall protection system, as it is known in the state of the art, typically comprises: an interception structure, a support structure and connection components. Further details of each of these elements will be provided in what follows.

[0021] The interception structure has the function of bearing the direct impact of the mass (rocks or debris flow), deforming elastically and/or plastically, and transmitting the stresses to the connection components, the support structure and the foundations. This interception structure usually comprises a main net made up of metallic wires or cables of different types and/or materials. It may also comprise additional layers: usually with a finer meshwork than the main net made up of cables and/or wires or other materials. A number of typologies of metal nettings are known, such as, for example, loose mesh nettings and single or double twisted hexagonal mesh nettings. Each netting typology generally has a specific application, depending on the technical characteristics of the metal wires forming it and on how those wires are mutually arranged.

[0022] The support structure has the function of maintaining the interception structure erected and unbent, which is by nature not rigid: generally it is connected to the interception structure by the connection components. The support structure typically comprises a plurality of posts made of different materials, geometries and/or lengths and which may be provided at the bottom with a hinge. Typically, posts made of profiles HEB or HEA are used, allowing to reduce the weight transported. The head of the post comprises drillings and additional welded elements intended to guide the support cables. A plate is arranged on the ground: this ground plate is fixed to the ground either directly or by a concrete plate typically by means of one or several anchor bolts. When concrete foundations are used, the bars can be embedded into the fresh concrete.

[0023] The connection components have the function of transmitting the stresses originated from the impacts onto the interception structure to the foundation. In order to allow the deformation of the interception structure, connection components can be installed in the structure, allowing a controlled lengthening of it. These connection components usually consist in connecting ropes, steel cables, wires and/or bars of different types and/or materials, junctions, wire rope clips or energy dissipating devices (elements which are able to dissipate energy and/or allow a controlled displacement when stressed). Among the connection components, the following ones can be cited:

• Cables. The support cables run along the upper and under perimeter between the posts, the nets are fixed to these cables, directly or with shackles.
• Bearings. The support cables are directed towards the head of the posts and the ground plates through the so-called bearings or running wheels, the function of which is similar to the cable pulleys (called pulley or running wheel type). The bearings or running wheels are always aligned in the direction of the cable so the cable contact area is increased. As they roll over the cable surface, the bearings or running wheels guarantee that the said cable slides almost without friction through the guideways, when an impact takes place. Therefore, the support cables remain intact and the breakage of the wires is avoided.
• Cable clips and shackles. They are accessories used for the correct fixing of the ends of the cables. The number of cable clips and their spacing will depend on the cable diameter defined for each system.
• Braking means or energy dissipating devices. Each section of the device will be provided with a plurality of braking means. The braking means present variable configurations depending on the manufacturers (for example with a U shape, a ring shape, etc.). When an impact occurs, a piece (insert) displaces alongside a fastener so energy is absorbed and at the same time the cable is released. The characteristics of this material allow to maintain the graph stress-deformation, with a constant stress value as elongation occurs. This translates into a design of light systems with optimized loads in the anchorage points.
• Cable anchorages. Flexible elements made out of double helicoidal cable, protected in the area of the head exposed (to the outside) by one or double tube of galvanised steel.

[0024] The elements described configure what the guideline ETAG 07 calls "a falling rock protection kit". Apart from these elements, the system further comprises a foundation which transmits the forces derived from the block impact to the ground. Figures 1 and 3 give an example of a falling rock protection system according to the known prior art and explain in general terms the different components of the system according to ETAG027.

[0025] The support structure and the barrier so configured object of the present invention comprise the above-mentioned elements, but present improvements with respect to them in order to simplify the said structures for facilitating their installation and for optimizing costs, without losing effectiveness nor functional efficiency.

[0026] The support structure of the invention and the so configured dynamic barrier against occasional or frequent rockfall, shallow landslide or debris flow, has limited flexibility, with no braking means or with a reduced use of braking means, absorption ability in its entire interception surface, with easy, fast and safe installation, as well as having lower costs.

[0027] The novel support structure of the invention applied on a "semi-dynamic" barrier is based on a novel support structure configured as a post of tubular profile, simplified and without the need of any welding, directly positioned over an anchorage by means of an elongated screw and a fastener, so the ground plate of the prior art is removed. Said structure is fixed by single or double top and bottom perimeter cables, as well as by cables towards the anchorages uphill. Moreover, stronger dimensioned ring nets allow the reduction or even suppression of any type of braking means or energy dissipating devices.

[0028] Therefore, the main novel features of the barrier comprising the support structure of the invention with respect to the barriers in the prior art are: the possibility of removing any braking means, the removal of the ground plate, the total lack of welding on the posts with a structural function, the almost lack of mechanisation of the post having a tubular profile and the tubular profile guides the cable without any bending which damages the function of the cable. With these novel structural characteristics, the necessary elements to build up the semi-dynamic barrier of the invention are around ten, compared to the almost thirty different elements needed in the systems used at present.

[0029] The removal of the braking means is replaced by elements reinforced in its dimensioning, mainly a plurality of rings having a high intrinsic energy absorption ability. The result is a more robust product with the required flexibility to absorb the defined energy with the minimum possible deformation. The lower flexibility allows the installation of the barriers in areas closer to the areas to be protected, for example on the edges of the roads or railroads, as the impacts do not generate high deformation of the barriers and so do not penetrate in the roads or paths.

[0030] The higher stiffness reduces the need of maintenance, as the accumulation of small impacts, shallow landslides or debris flow does not deform the barrier. By avoiding this deformation, the maximal protection capacity is maintained. The main characteristic of the barrier comprising the support structure of the invention is its lower deformation, compared to that in the known prior art, with significantly lower number of components. This leads to the partial or complete removal of the energy absorption braking means, to the reinforcement of the post, net and cables components, therefore achieving a more favourable weight/deformation ratio and highly reducing the need of maintenance of the barriers. Reducing the number of components and making them simpler leads not only to a high cost reduction, but also allows innovating in a novel logistic concept enabling provisioning site works in lower timings as those existing at present. The total number of components for the barriers of the invention is typically less than ten standardized components.

[0031] The main characteristics and related advantages of the barrier system developed by the present invention are the following:

• Simplification of the support structure.

[0032] The assembly post-plate-anchorage is simplified in the barrier according to the invention: no ground plate is used in the barrier of the invention, still maintaining the functionalities of the assembly. The assembly simply comprises an anchorage comprising an elongated screw, having an orifice used for fixing it to the post by means of a fastener. In conventional barriers, posts are fixed onto a plate by means of a fastener which, fixed to the plate in a vertical gusset by a screw, allows the post to tilt. Said plate is screwed to the ground by anchorage bars inserted into the said ground. On the contrary, the barrier of the invention does not comprise any plate, but comprises instead the mentioned drilled screw. This screw comprises a tubular elongated body with an internal threaded nut, comprising on its upper end two drills transversally aligned to allow their connection to the post by means of a fastener. Also, the post used in the barrier of the invention has a tubular profile which provides a higher stiffness in the case of direct impacts to the post. Besides, said tubular profiles are tailored cut and have no welding, that is, they are made of one single piece. The support structure in a conventional barrier, that is, the posts of it, are usually made out of a machined HEB or HEA metallic profile comprising drills and a plurality of pieces or plates welded, onto which the different connection elements, such as shackles or cable clips are mounted or fixed. Therefore, the posts in the barrier of the invention being made of standard ones, the manufacturing of them is highly simplified and the disadvantages that may arrive from the welding are also avoided. As a consequence of this connection between post and anchor, this union is moved to inside of the post, where it is protected from direct impact of rockfall.

• Limitation of the deformation of the barrier and optional removal of braking means

[0033] Removal of braking means is replaced by reinforced elements such as the plurality of rings and higher diameters of the cables. Conventional barriers typically comprise braking means absorbing impact energy: these braking means are needed in order to create very flexible barriers, having a very high energy absorption ability but also requiring big deformation areas. Moreover, these braking means do not recover their original shape once they have been actuated. Therefore, a barrier with braking means requires frequent maintenance and/or replacement works, once rockfall, landslide or debris flow has occurred. On the contrary, the barrier of the present invention does not require said braking means as it uses connection cables with higher stiffness, maintaining flexibility, but with a lower deformation. Thus, the maintenance needs are reduced and the installation durability is longer. In any case, the barrier of the invention can also optionally comprise tensioning elements or braking means.

• Reduction of the number of components.

[0034] As the components making up the barrier of the invention are mostly standard ones, the flexibility in manufacturing and in the delivery of said components is highly improved.

• The logistics for supplying the barrier components decrease provisioning timings.

[0035] The result is a more robust barrier, with the required flexibility to absorb the defined energy with the minimum possible deformation. Most of the elements used in the dynamic barriers known in the state of the art must be manufactured in the factories of each manufacturer, as the posts, the braking means and the nets are exclusive components differently sized and configured depending on each manufacturer: this entails high manufacturing costs, tailored manufacturing for each project and long delivery timings. On the contrary, with the barrier of the invention, most of the elements used are standard ones, except for the net (which is a more specific net made of a high strength wire) and the articulated joint element between the anchorage and the post or support structure, previously described: as most of the elements are standard ones, they can be obtained locally (in each country), therefore simplifying the barrier and reducing its cost.

Brief description of the drawings

[0036] Further features, advantages and objects of the present invention will become apparent for a skilled person when reading the following detailed description of nonlimiting embodiments of the present invention, when taken in conjunction with the appended drawings, in which:

Fig. 1 shows a back view of a falling rock protection kit according to the prior art, as represented in the guideline ETAG 027.

Fig. 2 shows a schematic view seen from above of a flexible barrier for protection against the fall of rocks according to a possible embodiment in the known prior art, showing its general configuration and its main parts and elements, as well as the configuration and arrangement of these.

Fig. 3 shows a side view of a falling rock protection kit according to the prior art, as represented in the guideline ETAG 027.

Fig. 4 shows a perspective view of one single section of a flexible barrier for protection against the fall of rocks according to the prior art, as shown in Figures 1 or 2, showing in more detail the main elements that it comprises.

Fig. 5a shows a perspective view of a ground plate and an anchorage, also showing the different elements used, in a flexible barrier for protection against the fall of rocks according to the prior art.

Fig. 5b shows a section view of the articulated joint between the post and the anchorage, using a ground plate, in a flexible barrier for protection against the fall of rocks according to the prior art, also showing the different elements used.

Fig. 6 shows a perspective view of a drilled screw configuring the articulated joint element between posts and anchorage bars in a support structure for a falling rock protection system according to the present invention, also showing its external configuration.

Fig. 7 shows a section view of the drilled screw in Figure 6, represented in its position of use as articulated joint between the post and the anchorage bar, in a support structure for a falling rock protection system according to the present invention, showing its configuration and the way it is incorporated between these two elements.

Fig. 8 shows a perspective view of an example of a post used in a support structure for a barrier according to the present invention, showing its tubular configuration without welding.

Fig. 9 shows several sections of the support structure object of the invention showing the different parts configuring it.

Figs. 10a-b show perspective views of a post, support structure and other elements configuring a dynamic rockfall barrier used in the known prior art.

Figs. 10c-d show perspective representative views of the post head for an intermediate post and for a side post, respectively, in a support structure according to the present invention used in a dynamic rockfall barrier.

Figs. 10e shows a perspective representative view of the post base for an intermediate post or for a side post, in a support structure according to the present invention used in a dynamic rockfall barrier.

Detailed description of exemplary embodiments

[0037] Figure 1 shows a back view of a falling rock protection kit typically used in the prior art, following the guideline ETAG 027. As represented in this Figure, the interception structure comprises a net 2 made out of several functional modules 2a and several connection components comprising a plurality of cables 5, and post 3 to support the structure and to anchor it to the ground. The falling rock protection kit of the prior art further comprises several energy dissipating devices 20, typically braking means to dissipate the kinetic energy of the impact and convert it into braking energy. Figure 3 represents a side view of the falling rock protection kit of Figure 1, according to the guideline ETAG 027, and further showing the foundation anchorage of the structure to the ground, by means of several anchorage bars or bolts 4. As it will be further explained in more detail, in reference to Figures 5a and 5b, the connection of the posts 3 to the anchorage bars 4 also needs the use of a ground plate 8, as schematically represented in Figure 3.

[0038] Figure 2 shows a general overview of a falling rock barrier according to the prior art: a similar configuration is also used for the falling rock barrier 1 according to the present invention. The falling rock barrier 1 of the invention comprises an interception structure, typically a net 2, used for intercepting occasional failings of rocks or other objects, and a support structure comprising a plurality of posts 3 and a plurality of anchorage bars or bolts 4. The net 2 is fixed through the plurality of posts 3 and both the net 2 and the posts 3 are anchored in the ground through the anchorage bars or bolts 4, in an articulated manner. Typically, the barrier 1 of the invention is arranged on a ground that is sloped or vertical. The falling rock barrier 1 of the invention further comprises connection components transmitting the stresses originating from the impacts onto the net 2 to the foundation through the support structure. The connection components typically comprise a plurality of cables 5 as shown in Figure 2: some of these cables 5 join the distal ends of the posts 3 to the ground. Other cables 5 join the lateral ends of the net 2 to the ground, longitudinally crossing the upper and the lower ends of the net 2 and also the middle part of said net 2. Yet another set of cables 5 also join the net 2 and/or the posts 3 to the anchorage bars or bolts 4, anchored in the ground. According to their position and function, the different cables 5 described are known in the prior art as Upper /Lower/Lateral or Upslope ropes. In the known state of the art, the cables 5 further comprise energy dissipating devices 20, typically braking means (as represented in Figure 1, though not represented in Figure 2). In a preferred embodiment, the configuration of the present invention does not comprise these energy dissipating devices 20 or braking means (the configuration of the invention would be similar to that represented in Figure 2). Figure 4 shows a detailed view of a part of the net 2 and its connection to the ground by cables 5, according to the known prior art.

[0039] This configuration shown in Figure 2 is in principle common to the barriers of the known prior art and is also used in the falling rock barrier 1 developed by the present invention. Departing from this configuration, the barrier 1 of the invention is mainly distinguished from the ones in the prior art in that the posts 3 are joined to the anchorage bars or bolts 4 in a very simplified way: in the prior art, the posts 3 are joined to the bars 4 by means of fasteners 6 acting as an axis in order to allow a certain degree of articulated movement of said joint, further using a ground plate 8; however, in the falling rock barrier 1 of the invention, the posts 3 are joined to the anchorage bars 4 uniquely by a simplified connecting or joining element 7, preferably configured as a drilled screw. Further details will be given in what follows.

[0040] Figure 6 shows in detail the configuration of the said drilled screw 7, comprising an elongated tubular or rectangular body comprising a threaded part 7a arranged, at least in its inner lower part (see detail in Figure 7). The external shape of the drilled screw 7 can adopt different shapes (figure 6 shows two possible exemplary external shapes). The drilled screw is perforated by two drills 7b transversally aligned with respect to the elongated tubular body of the screw 7. The fastener 6 is inserted through the two drills 7b of the screw 7 and the connection to the post 3 (aligned in an axis 50) is done through corresponding drills 3a in the post 3 as shown in Figure 7: therefore, the fastener 6 connects the screw 7 to the post 3 by passing through the drills 7b (in the screw 7) and the drills 3a (in the post 3), configured for such proper connection.

[0041] The drilled screw 7 and the fastener 6 are preferably made of steel, though they can also be made in special reinforced steel, in order to strengthen them.

[0042] The post 3 is configured having a tubular shape and has the corresponding inner dimensions needed to adjust perfectly over the external dimension of the drilled screw 7, as represented in detail in Figure 7, so an easier connection is achieved. In the embodiment shown in Figure 7 the connecting elements 7 are partially positioned inside of the posts 3. However, in other embodiments, the connecting elements 7 could be completely positioned inside of the post 3.

[0043] The tubular shape of the posts 3 can adopt different shapes, such as circular hollow, rectangular hollow, square hollow, hexagonal, etc. It is important to mention that, in any case, the tubular section of the post will have rounded edges, as represented when looking at Figure 8. This represents an important advantage, as the cables 5 can be tensed around the post 3 without any shearing or cutting risk. As stated above, in the known prior art, the posts are made by having a section in H (typically HEB or HEA profile) that will shear and end by cutting the cables if they would be tensioned around. This is the main reason why, in the support structures of the prior art, the cables are fixed to extra plates and elements that are provided with rounded edges. Contrary to this, the posts in the supporting structure of the invention are configured by full sections of tubes without welding, which represent a less costly configuration avoiding failure risks in the welding.

[0044] It should be noted that the drilled screws 7 used in the falling rock barrier 1 of the present invention depart from standardized parts: in fact, these screws 7 are adapted from existing parts used as bolt extensions, that is, when the anchorage bars or bolts 4 are very long, it is necessary to join several of them together. This is typically done by using these threaded parts. The drilled screws 7 are made in fact by taking these standardized parts (bolt extensions) making a transversal orifice for the fastener.

[0045] Figure 5b shows, on the other hand, the connection of the posts 3 (aligned according to an axis 51) and the anchorage bars 4 (aligned according to an axis 52) according to the prior art. The connecting or joining element between the posts 3 and the anchorage bars 4 is a ground plate 8. This ground plate 8 also comprises a nut 9 (Figure 5b shows a cap nut, but any type of fastener with a threaded hole would be suitable) for its fixation to the anchorage bars 4, and further comprises two vertical extensions 8a where the fastener 6 will be fixed and to which a lower projection of the mechanised profile configuring the post 3 is inserted. Therefore, the higher sophistication of the ground plate 8 and the installation complexity are evident in the installation according to the prior art. Moreover, these ground plates 8 in the prior art have to be produced by welding different gussets configuring the plate. These welding therefore imply weak points in the overall structure. The components of the connection of anchor-plate-post are exposed to impacts from rockfall and use to be the weak point of rockfall protection system.

[0046] Figure 5a shows an example of a possible configuration of the anchoring of the ground plate 8 according to the prior art: it is also represented in this Figure that the ground plate 8 is made out of a plurality of gussets that configure the final ground plate 8. The ground plate 8 is fixed in this example by means of a pair of washer plates and nuts 109, 110 so as to prevent its rotation. Further, the plate 8 is anchored to the ground or soil 1110 by using a main anchor and optionally a stabilization tube 104, 105 and further a securing anchor 106. Other anchoring configurations of the ground plate 8 are also possible, such as in rocks, in concrete, etc. as variants of the anchoring exemplified in Figure 5a.

[0047] Figure 8 shows in detail the configuration of the posts 3 in the falling rock barrier 1 according to the present invention: it can be seen that these posts comprise drills 3a arranged and aligned so that the fastener 6 can go through. These posts are configured by full sections of tubes, that is, by single parts without welding. Contrary to the posts used in the barriers of the prior art, having a profile in H, on which all sorts of machining and/or mechanization is done (typically welding gussets according to the details in Figures 10a-b) to be able to fasten or fix onto them a plurality of connecting components needed, such as rings for the cables, pulleys, etc. Contrary to this, the configuration of the invention simply uses a post 3 (a tube) comprising drills 3a and also comprising cable clips 30 through which the cables 5 pass, these cable clips 30 being fixed to the posts 3 by two nuts or two fasteners with a threaded hole for each clip 30, as shown in Figure 9.

[0048] Looking to Figure 8 in detail, the drills 30a are intended to receive the cable clips 30, as already explained. According to one embodiment, these drills 30a are made in two opposite sides of the post 3. Another advantage of the invention will be to provide the post 3 with several rows of multiple drills 30a in order to arrange the cable clips 30 according to the soil requirements: because the ground may be irregular, the cables are therefore guided as close as possible to the ground, therefore generating less space in the line of cables (lower side) to the ground.

[0049] Another advantage of having several rows of drills 30a is the possibility of having the post 3 partially embedded into the ground or the concrete. For this purpose the posts 3 may have different lengths and according to the soil requirements may be partially sunk in the ground. In this way, the stresses generated onto the posts 3 are transmitted (at least in part) directly to the ground. As there are no ground plates, it is not necessary to carry out any excavation. Therefore this partial embedment of the post 3 provides an additional protection of the joint formed by the fastener 6 and the connecting element 7.

[0050] The combination of posts 3 of different lengths and the provision of rows of drills at different heights, allows a perfect guidance of the cables. The barriers known in the prior art do not offer such flexibility of adaptation to the ground as they have a complex configuration with multiple welded elements.

[0051] Figure 9 shows several possible configurations for the setup of the posts 3 in the ground, also showing their installation in slope areas (the valley sides and the hill sides are also represented in the said Figure 9). The lower part of the posts 3 comprise the drills 3a for the fastener in order to join the posts 3 to the anchorage bars 4, these bars 4 being therefore anchored to the soil or ground. Typically, both the upper and the lower parts of the posts 3 in the barrier 1 of the invention comprise cable clips 30, preferably fixed to the posts 3 by two nuts or two fasteners with a threaded hole for each clip 30, in order to configure proper paths for the cables 5 to go through, so the posts 3 and the cables 5 tension the net 2 and configure its support structure, the net 2 receiving the occasional impacts from the falling of rocks or other objects.

[0052] In a post 3 used in a falling rock barrier according to the known prior art, the profile of the post 3 is in H or double T (HEB or HEA profile) and joining the net 2 to the post 3, with a plurality of pieces and elements needed, is very complex. Figures 10a-b show a further detail of the said assembly in the prior art, showing its full complexity, contrary to the simplicity in the one used in the barrier 1 according to the invention, as represented in Figures 10c-f, where it can be seen the tubular profile of the post 3, with the drills 3a for the fastener 6 to join the post 3 to the bar 4, and the cable clips 30 arranged as passage for the cables 5.

[0053] Referring now to Figures 10a and 10b, they show the configuration of a dynamic rockfall barrier and its support structure according to the known prior art. Figure 10a shows a post 3 anchored to the ground on its post base 32 and with a post head 31. Cables 5 are joined to the post head 31 by means of guiding elements 60: the cables 5 are then anchored to the ground by upslope anchors 36. As shown in Figure 10a, this known configuration also comprises energy dissipating devices 20 (typically braking means) to absorb and dissipate energy from occasional impacts. A net 2 is joined to the post 3 as it will be explained in more detail later, referring to Figure 10b. The support structure in the known prior art comprises a base plate 8 fixed to the ground by anchorage bars 41 and 42 (the more representatives), nuts 43 and 44, and washers 45, 46 (the washer 45 is vertical and works under compression and shear, while the washer 46 is an anchorage working under traction). On the contrary, the support structure of the invention (as represented in Figure 7) is much simpler: the anchorage of the post 3 to the ground is done directly by an elongated screw (connecting element 7) having an orifice 7b through which a fastener 6 is arranged in order to fix the post 3 to the connecting element 7. The post 3 of the invention is tubular and is made of one single piece, requiring no welding and the connecting elements 7 are partially or completely positioned inside of the posts 3.

[0054] Furthermore, the posts 3 used in the prior art, as discussed, have a profile HEB or HEA, that prevents the cables 5 (tensioning the posts to the ground) and the cables tensioning the net 2 ((upper ropes 23, optionally middle ropes 22 (used in very high energy barriers) and lower ropes 21) to be directly tensed around the post 3 as there will exist a high risk of shearing or cutting of these cables. Therefore, it is necessary to use rounded pieces (of the pulley or running wheel type, as shown by pieces 80 and 90 in Figure 10b) that will avoid said risk for the cables. These pieces 80 and 90 are welded to the posts 3, which complicates the structure, the installation and increases the cost.

[0055] On the contrary, looking at Figures 10c and 10d of the invention (showing the post head for an intermediate post and for a side post, respectively) and at Figure 10e of the invention (showing the post base 32 for an intermediate post or for a side post), the cables can be fastened around the post 3 without the need of these rounded pieces that have to be welded, as the configuration of the post is tubular with rounded edges. Moreover, the post 3 of the invention will be provided with cable clips 30 through which the cables (to tense and support the net and to tense and support the posts themselves) can pass. The configuration according to the invention is simpler and much more cost effective.

[0056] According to another embodiment of the falling rock barrier 1 of the invention, the tubular profile configuring the post 3 can be filled with cement and/or mortar and/or concrete, at least partly. With this embodiment, a structural reinforcement of the post 3 is obtained in a very simple and non-costly way. The thickness of the post is variable depending on the reinforcement needed for it and on whether or not it will be filled with cement and/or mortar and/or concrete. The known posts in the state of the art, having a profile HEB or HEA, are not capable to resist impacts but sometimes neither to the compression force of the upper and lower cables over them. A rounded post (or rectangular with rounded edges) that can even be filled with concrete or cement increases resistance to impacts remote from the centre of the panels, as it is defined by EOTA. Decisively, the filled rounded post (or rectangular with rounded edges) presents a development of the barriers towards barriers able to resist impacts over the whole of their protection area.

[0057] This reinforcement of the posts 3 is particularly important in cases where occasional impacts can happen not in the net 2 but in the posts 3 themselves. In the known prior art, the profile of the posts in H is not adapted for these direct impacts on the posts, as these profiles do not offer a high structural resistance against such impacts. Moreover, filling the inner part of the profile of the posts 3 with cement and/or mortar and/or concrete can be done directly in situ at the work site during the installation of the falling rock barrier 1.

[0058] There are two possibilities for filling the post 3 with cement and/or mortar and/or concrete:

• A first possibility is to fill the post 3 only partially with cement and/or mortar and/or concrete keeping the articulated movement of the post thanks to the fasteners 6. The post is first arranged in its installation position in situ and then a cover or lid (having the same section as that of the post) slides and falls inside the section of the post 3 until it is stopped by the fastener 6: once the lid is in its position, the post 3 is filled with cement and/or mortar and/or concrete using the cover or lid as lost formwork.
• A second possibility is to fill completely the post 3 with cement and/or mortar and/or concrete. In this case, the post loses its articulated movement as the joint formed by the fastener 6 and the connecting element 7 is embedded in the cement and/or mortar and/or concrete. The post is first arranged in its installation position in situ and then, the lower part of the structure (the part from the lower side of the post to the ground) is held by a piece having the same section as the post (as an extension of the post to the ground). These pieces configure in fact a formwork: once the formwork is prepared, concrete and/or mortar and/or cement is poured from the upper part of the post, arriving to the ground this time, so the fastener 6 and the connecting element 7 will be embedded in it, without any possibility of movement once the cement and/or mortar and/or concrete has cured.

[0059] As already described, a particular advantage of the structure of the invention is that the components configuring it, with the exception of the net 2 and the drilled screw 7 are standard elements that can be easily obtained in the market. The net 2 is more specific but the same as used in similar prior art falling rock protection barriers, and the drilled screw, as described previously, is a standard part used as bolt extension where two orifices have been made. Therefore, contrary to the existing barriers in the prior art, specifically designed and made for each project, the barrier of the invention comprises standard elements easily obtainable or uses standard elements slightly modified.

[0060] Although the present invention has been described with reference to preferred embodiments thereof, many modifications and alternations may be made by a person having ordinary skill in the art without departing from the scope of this invention which is defined by the appended claims.

Claims

1. Support structure for a dynamic rockfall barrier, the barrier comprising interception means (2) for receiving the impact from occasional or frequent rockfall, shallow landslide or debris flow, deforming and transmitting the stress to the ground, and a plurality of cables (5) for supporting the interception means (2) and transmitting the stresses generated onto the interception means (2) to the ground;
wherein the support structure comprises
a plurality of posts (3) each one directly fixed to the ground by means of an anchorage bar (4) arranged aligned
and wherein
the posts (3) have a tubular shape and are joined to the anchorage bars (4) uniquely by a connecting element (7) and a fastener (6) passing through one or more drills (7b) in the connecting element (7) and one or more drills (3a) in the post 3.

2. Support structure for a dynamic rockfall barrier according to claim 1 wherein the posts (3) are made of one single piece.

3. Support structure for a dynamic rockfall barrier according to claim 1 or 2 wherein the posts (3) have rounded edges.

4. Support structure for a dynamic rockfall barrier according to any of claims 2-3 wherein the tubular shape of the posts (3) is circular hollow, rectangular hollow, square hollow, hexagonal hollow or any other polygonal hollow shape.

5. Support structure for a dynamic rockfall barrier according to any of the previous claims wherein the posts (3) comprise a plurality of drills (30a) intended to receive cable pins (30) through where the cables (5) pass.

6. Support structure for a dynamic rockfall barrier according to claim 5 wherein the cable pins (30) are arranged on any two of the opposite sides of the posts (3), being fixed to the posts (3) by two nuts or two fasteners with a threaded hole for each clip 30.

7. Support structure for a dynamic rockfall barrier according to any of the previous claims wherein the connecting elements (7) comprise a drilled element or screw with a threaded part (7a).

8. Support structure for a dynamic rockfall barrier according to claim 6 wherein the drilled element or screw (7) comprises two drills (7b) transversally aligned with respect to the elongated tubular body of the drilled screw 7.

9. Support structure for a dynamic rockfall barrier according to any of the previous claims wherein the connecting elements (7) are partially or completely positioned inside of the posts (3).

10. Support structure for a dynamic rockfall barrier according to claim 9 wherein the connecting elements (7) have an external shape matching with the internal shape of the posts (3), comprising an inner threaded part (7a).

11. Support structure for a dynamic rockfall barrier according to any of the previous claims wherein the connecting elements (7) and/or the fasteners (6) are made of steel and/or on special reinforced steel.

12. Support structure for a dynamic rockfall barrier according to any of the previous claims wherein the posts (3) are at least partially filled inside their profile with cement and/or mortar and/or concrete.

13. Falling rock barrier (1) structure comprising a support structure according to any of the previous claims.

Drawing