EP4097302B1

EP4097302B1 - An impact absorbing unit of a rockfall protection gallery and the relative rockfall protection gallery

Info

Publication number: EP4097302B1
Application number: EP21708362.5A
Authority: EP
Inventors: Pasquale Impero
Original assignee: Individual
Current assignee: Individual
Priority date: 2020-01-28
Filing date: 2021-01-27
Publication date: 2024-01-24
Anticipated expiration: 2041-01-27
Also published as: IT202000001579A1; EP4097302A1; WO2021152475A1; ES2971538T3

Description

FIELD OF THE INVENTION

The present invention relates to the technical sector relating to impact absorbers. In particular, the present invention relates to an impact absorbing unit of a rockfall protection gallery and to a relative rockfall protection gallery.

DESCRIPTION OF THE PRIOR ART

In general, along the roads crossing mountainous, valley and riverside territories, the galleries constructed are of the rockfall protection type, i.e. a gallery provided superiorly with a layer of aggregate material for protection of the road affected by the fall of masses.
This layer of aggregate material (100) covers the upper part of the rockfall protection gallery (101), in order to partially or completely absorb an impact caused by a falling mass (103) on the rockfall protection gallery (101) and, therefore, reduce the intensity of the force transmitted by the mass (103) onto the rockfall protection gallery (101) (see figures 1A and 1B in which the rockfall protection gallery (101) and the mass (103) have been illustrated schematically). During the fall of the mass (103), the mass (103) will impact against the layer of aggregate material (100), transferring partially or completely its kinetic energy, owing to the principle of transfer of the quantity of motion, to a surface portion (102) of the layer of aggregate material (100), which will tend, consequently, to move towards the most external end of the layer (100) (see figures 1A and 1B).
A drawback of this system is linked to the phenomenon of dynamic amplification.
In detail, following the above-described transfer of kinetic energy, the movement of the surface portion (102) of the layer of aggregate material (100) will transmit, onto the rockfall protection gallery (101), an overall force having a greater intensity than that of the overall force transmitted by the mass during the relative deceleration pathway on the rockfall protection gallery (101).
A further drawback is represented by the fact that, following the impact and the movement of the surface portion (102) of the layer of aggregate material (100), the relative degree of compacting of the layer of aggregate material (100) will tend to increase.
However, the more compact the layer of aggregate material (100) is, the greater the intensity of the overall force transmitted by the mass (103) to the rockfall protection gallery (101) will be, as the quantity of kinetic energy that the falling mass (103) will transfer to the layer of aggregate material (100) will be smaller
Further, the above-described configuration is progressively more effective (i.e. the greater the quantity of kinetic energy transferred to the layer of aggregate material (100)), the greater the thickness of the layer of aggregate material (100) covering the rockfall protection gallery (101).
This involves a considerable weight that bears down on the rockfall protection gallery (101).
CN 109 183 640 discloses an anti-seismic, debris-flow-resistant and anti-rockfall shed-tunnel structure comprising an anti-seismic foundation structure, an energy dissipation structure and a rock blocking structure, wherein the anti-seismic foundation structure comprises: a plurality of foundations with grooves arranged along the longitudinal direction of a road, damping devices arranged in the grooves and support columns arranged in the grooves Further, the energy dissipation structure comprises a concrete column arranged in a backfilled soil layer and a waste tire arranged on the concrete column.
CN 109 653 109 discloses a spring and grid combined cushion seismic reduction device applicable to emergency rescue and disaster relief steel shed tunnels. The spring and grid combined cushion seismic reduction device comprises a grid layer and a spring cushion layer. The grid layer and the spring cushion layer are sequentially laid on the top of a steel shed tunnel frame from bottom to top.
CN 107 245 962 discloses a hanger tunnel shock absorber. The hanger tunnel shock absorber comprises a metal tube of which the two ends are opened and a lining body which is made from an anti-shocking protective material, and the side wall of the metal tube is configured to be in a corrugation shape; the lining body is placed in the metal tube, the height of the lining body is lower than that of the metal tube, and gaps are formed among all the side walls of the lining body and the inner wall of the metal tube.

SUMMARY OF THE INVENTION

in the light of the above, the aim of the present invention consists in obviating the above-described drawbacks.
The above aim is obtained by means of an impact absorbing unit of a rockfall protection gallery according to claim 1 and by a relative rockfall protection gallery according to claim 14.
At least a part of the collapsible tubular elements of the plurality of collapsible tubular elements, when compressed by a falling mass on the rockfall protection gallery, will deform in an irreversible way, absorbing the kinetic energy of the falling mass and consequently limiting the intensity of the overall force transmitted to the rockfall protection gallery following the fall of the mass.
Further, the plurality of connecting elements and the plurality of collapsible tubular elements are fixed to one another in such a way as to ensure a folding process and, therefore, a crushing of each collapsible tubular element along the relative extension axis on each connecting element.
Should there be a falling of masses in succession, each mass will determine the deformation of a part of collapsible tubular elements of the plurality of collapsible tubular elements and this makes the impact absorbing unit, object of the present invention, effective also in situations where there is a successive falling of masses. Further, each collapsible tubular element being hollow will have the effect that the plurality of columns, during use, will bear down on the rockfall protection gallery with a lower weight than the layer of aggregate material of the prior art.

BRIEF DESCRIPTION OF THE DRAWINGS

Specific embodiments of the invention will be described in the following part of the present description, according to what is recited in the claims and with the aid of the appended tables of drawings, in which:

figure 1A and figure 1B are a perspective view and a section view of a rockfall protection gallery provided superiorly with a layer of aggregate material of the prior art;
see figures 2, 3, 4 and 5 are perspective views of an impact absorbing unit of a rockfall protection gallery, object of the present invention, according to different embodiments;
figure 2A is a transversal section view of figure 2;
figure 3A is a transversal section view of figure 3;
figure 4A is a transversal section view of figure 4;
figure 5A is a transversal section view of figure 5;
figure 2B is a schematic view of detail K of figure 2;
figures 6-9 are schematic views of the impact absorbing unit of figure 3, during different steps of irreversible compression deformation of the plurality of collapsible tubular elements caused by the fall of a mass;
figure 10 is a schematic view of a part of a rockfall protection gallery also object of the present invention;
figures 11 and 12 are views of graphs, respectively, of the trend over time of the value of the impact force and the value of the transmitted force.

DESCRIPTION OF PREFERRED EMBODIMENTS

With reference to the appended tables of drawings, reference numeral (1) denotes an impact absorbing unit of a rockfall protection gallery, object of the present invention, wherein: it comprises a plurality of columns (2) which are arranged flanked to one another; each column (2a) of the plurality of columns (2) comprises: a plurality of collapsible tubular elements (3); a plurality of connecting elements (4) for connecting the collapsible tubular elements (3) to one another; each collapsible tubular element (3a) of the plurality of collapsible tubular elements (3) comprises an end edge (5) and has a length (L) and a transversal section (S) which are inter-related in order to determine a folding process, i.e. an irreversible compression deformation of the collapsible tubular element (3a) which leads to collapse thereof, and therefore a crushing thereof, along the relative extension axis (X) when the collapsible tubular element (3a) is subjected to an axial force having an intensity that is at least equal to a critical force value; each connecting element (4a) of the plurality of connecting elements (4) comprises a first face (6) and a second face (7), opposite the first face (6), and is fixed to two collapsible tubular elements (3a, 3b) of a same column (2a) of the plurality of columns (2), which are consecutive to one another, so that the end edge (5) of a collapsible tubular element (3a) of the two collapsible tubular elements (3a, 3b) is fixed to the relative first face (6) and so that the end edge (5) of the other collapsible tubular element (3b) of the two collapsible tubular elements (3a, 3b) is fixed to the relative second face (7) (see figures 2-5 and 6-9 and 2B).
The impact absorbing unit (1) is configured in such a way that, during use, at least a part of the collapsible tubular elements of the plurality of collapsible tubular elements (3) deforms in an irreversible way, by effect of the compression determined by an axial force exerted by a mass (M) falling on the rockfall protection gallery (G) (see figures 2-5 and 6-9 and 2B).
In other words, for at least a part of the collapsible tubular elements of the plurality of collapsible tubular elements (3), which deforms in an irreversible way during use of the impact absorbing unit (1) of a rockfall protection gallery (G), is meant the collapsible tubular elements of the plurality of collapsible tubular elements (3) arranged on the top along the extension axis of each column (2a), i.e. the number of collapsible tubular elements closest to the mass (M).
It is specified that by rockfall protection gallery (G) is meant an artificial gallery realised to protect the road bed from falling masses.
In detail, each column (2a) of the plurality of columns (2) comprises a plurality of collapsible tubular elements (3) wherein each collapsible tubular element (3a) is arranged in succession to the preceding collapsible tubular element (3b) so as to be arranged above the latter (see figure 2B).
In other words, each column (2a) of the plurality of columns (2) comprises a plurality of collapsible tubular elements (3) which are arranged stacked on one another.
With particular reference to figures 2-5, the collapsible tubular elements of the plurality of collapsible tubular elements (3) are arranged along the extension axis of the column.
The extension axis of each column (2a) of the plurality of columns (2) can coincide with the extension axis (X) of each relative collapsible tubular element (3a) (see figures 4 and 5).
The plurality of connecting elements (4) is preferably suitable for reciprocally connecting collapsible tubular elements (3) of a same column (2a) of the plurality of columns (2) (see figures 2-5).
Each collapsible tubular element (3a) of a pair of collapsible tubular elements (3a, 3b) of the plurality of collapsible tubular elements (3) is preferably connected to the other by means of a single connecting element (4a) of the plurality of connecting elements (4) (see figure 2B).
In other words, in each column (2a) of the plurality of columns (2) there is an alternation of a connecting element (4a) of the plurality of connecting elements (4a) and a collapsible tubular element (3a) of the plurality of collapsible tubular elements (3).
Each connecting element (4a) of the plurality of connecting elements (4) fixed to two collapsible tubular elements (3a, 3b) of a same column (2a), which are consecutive to one another, enables definition of a determined value of length (L) of each collapsible tubular element (3a), i.e. the distance between two connecting elements (4a, 4b), which are consecutive to one another, in a same column (2a) (see figures 2-5).
In other words, the length (L) of a collapsible tubular element (3a) can be taken to be the distance between two connecting elements (4a, 4b) which are respectively fixed to the end edges (5) of the collapsible tubular element (3a) (see figures 2-5).
By the end edge (5) of each collapsible tubular element (3a) of the plurality of collapsible tubular elements (3) is meant the free end edge (5).
With particular reference to figures 2-5, the columns of the plurality of columns (2) extend in height so as to reach the same height value.
In this case, for the collapsible tubular elements of the plurality of collapsible tubular elements (3) having the same length values (L) and transversal section (S), the connecting elements of the plurality of connecting elements (4) can be arranged parallel to one another.
The plurality of connecting elements (4) advantageously ensures that there is a gradual deformation of the collapsible tubular elements of the plurality of collapsible tubular elements (3) subjected to the axial force exerted by the falling mass (M).
By extension axis (X) of each collapsible tubular element (3a) of the plurality of collapsible tubular elements (3) is meant the axial.
By axial force (X) is meant a force parallel to the extension axis (X) of each collapsible tubular element (3a) of the plurality of collapsible tubular elements (3).
With particular reference to figures 2-5, each connecting element (3a) of the plurality of connecting elements (3) is orientated in such a way that the extension axis (X) is transversal to the extension axis of each connecting element (4a) of the plurality of collapsible tubular elements (4) (see figure 2B).
With particular reference to figures 2A, 3A, 4A and 5A, each collapsible tubular element (3a) of the plurality of collapsible tubular elements (3) comprises a first portion (9) and a second portion (10) which are opposite one another and fixed to one another; wherein the first portion (9) and the second portion (10) comprise, respectively, a half-shell (11) and two fixing tabs (12) arranged respectively at the opposite ends of the half-shell (11).
The structure of each collapsible tubular elements (3a) of the plurality of collapsible tubular elements (3) advantageously enables realising a column (2a) having a smaller weight than the layer of aggregate material of the prior art. Further, the transversal section (S) of a collapsible tubular element (3a) can assume an overall value that includes both the value of the section, determined according to a transversal plane to the extension axis (X) of the collapsible tubular element (3a), and the value of the thickness of the half-shell (11).
The impact absorbing unit (1) preferably comprises maintenance means (13) for maintaining the columns of the plurality of columns (2) near to one another.
The maintenance means (13) advantageously realise a lateral containment of the plurality of columns (2) during the folding process.
In other words, the maintenance means (13) ensure that the columns of the plurality of columns (2) are maintained near to one another during the irreversible compression deformation of each collapsible tubular element (3a) along the relative extension axis (X).
The maintenance means (13) preferably comprise at least a cable (8) which winds about the plurality of columns (2).
Alternatively the maintenance means (13) can comprise a plurality of cables (13) which are arranged distanced from one another.
Further, the at least a cable (8), in combination with the plurality of connecting elements (4), ensures a gradual deformation of the plurality of columns (2) (see figures 6-9).
In other words, when a first mass (M) falls on the rockfall protection gallery (G) there will be a deformation of a first part of the columns of the plurality of columns (2), i.e. a first row of collapsible tubular elements (3a) which are part of different columns of the plurality of columns (2) (see figures 6 and 7).
Thereafter, when a second mass (M) falls on the rockfall protection gallery (G), there will be a deformation of a second part of the columns of the plurality of columns (2), i.e. a second row of collapsible tubular elements (3a), subsequently of the first row of collapsible tubular elements (3a), which are part of different columns of the plurality of columns (2) (see figures 6 and 7).
The events described in the foregoing will take place on the fall of masses in succession on the rockfall protection gallery (G), up to the complete deformation of the columns of the plurality of columns (2) (see figures 6-9).
Each column (2a) of the plurality of columns (2) can comprise a first terminal element (14) and a second terminal element (15).
The first terminal element (14) can be arranged at a relative end of a column (2a) of the plurality of columns (2) and the second terminal element (15) can be arranged at another relative end of the column (2a) of the plurality of columns (2). The end edge (5) of the collapsible tubular element (3a) is preferably entirely in contact with the first face (6) of the connecting element (4a) and the end edge (5) of the other collapsible tubular element (3b) is entirely in contact with the second face (7) of the connecting element (4a) (see figure 2B).
The fixing of each connecting element (4a) to the collapsible tubular elements of the plurality of collapsible tubular elements (3), as it interrupts the continuity of the collapsible tubular elements in each column (2a) of the plurality of columns (2), advantageously guarantees that during use the folding process takes place, i.e. the crushing of each collapsible tubular element (3a) against each connecting element (4a), determining a transformation of the kinetic energy of the falling mass (M) into deformation energy of the collapsible tubular elements of the plurality of collapsible tubular elements (3).
Each collapsible tubular element (3a) of the plurality of collapsible tubular elements (3) preferably externally forms a wall (16) having a plurality of faces (17); the faces of the plurality of faces (17) are adjacent to one another and intersect one another, identifying corresponding edges (18) (figures 3A and 5A).
With particular reference to figures 2-5, the edges (18) have an orientation that is transversal to the extension axis (X) of each collapsible tubular element (3a) of the plurality of collapsible tubular elements (3) so as to facilitate the folding process and prevent the setting off of the buckling process, i.e. an unpredictable process of deformation of each collapsible tubular element (3a) that is unpredictable.
Each collapsible tubular element (3a) of the plurality of collapsible tubular elements (3) preferably has a polygonal transversal section.
By way of example, the section can be square or rectangular, or even hexagonal.
It is advantageously possible to realise a form coupling between the collapsible tubular elements (3) of different columns (2) with the purpose of reducing the free space between one column (2a) and the other.
Each connecting element (4a) of the plurality of connecting elements (4) preferably has a planar extension so as to extend internally of the transversal section (S) of each collapsible tubular element (3a) of the plurality of collapsible tubular elements (3) (see figures 2A, 3A, 4A, 5A).
The maintenance means (13) are made of a metal material.
Each connecting element (4a) of the plurality of connecting elements (4) can comprise a plate (19) (see figure 2B).
Each collapsible tubular element (3a) of the plurality of collapsible tubular elements (3) is preferably made of a metal material.
In this case, each collapsible tubular element (3a) of the plurality of collapsible tubular elements (3) is preferably made of a metal material.
Each connecting element (4a) of the plurality of connecting elements (4) is preferably fixed by welding to the collapsible tubular elements of the plurality of collapsible tubular elements (3), which are consecutive to one another, of a same column (2a) of the plurality of columns (2).
A solid fixture is advantageously ensured between the connecting elements of the plurality of connecting elements (4) and the collapsible tubular elements of the plurality of collapsible tubular elements (3).
Alternatively, each collapsible tubular element (3a) of the plurality of collapsible tubular elements (3) can be made of a composite material or a plastic material.
In the event that each collapsible tubular element (3a) is made of a composite material, it is possible to use a reinforced fibre material, for example a polymer matrix material, such as epoxy or polyester resin, reinforced with glass fibres and/or carbon and/or kevlar.
Further, in this case, each collapsible tubular element (3a) of the plurality of collapsible tubular elements (3) can include a greater thickness at the relative area affected by the folding phenomenon, with the aim of increasing the impact energy-absorbent capacity of each collapsible tubular element (3a).
In the case where each collapsible tubular element (3a) is made of composite material, each connecting element (4a) is fixed to each collapsible tubular element (3a) by gluing.
Further, and also in the case where each collapsible tubular element (3a) is made of composite material, each half-shell (11) is coupled to another by gluing.
Differently, in the case where each collapsible tubular element (3a) is made of a metal material, each half-shell (11) is coupled to another by welding or mechanical fixing means.
A description follows of a rockfall protection gallery (G), also object of the present invention, comprising a plurality of impact absorbing units (110) according to any one of the embodiments described in the foregoing (see figures 6-9 e fig. 10 in which a part of the rockfall protection gallery of the present invention is illustrated); a containing wall (20) which is arranged, during use, so as to delimit a road and define with the road a passage channel (22) (see figure 10).
The plurality of impact absorbing units (110) can be arranged on the containing wall (20), so as lie above the passage channel (22).
By way of example, the rockfall protection gallery (G) can comprise a plurality of pillars (not illustrated) which emerge starting from the road up to the containing wall (20).
Alternatively, the rockfall protection gallery (G) can comprise a second containing wall (not illustrated) which emerges starting from the road up to the containing wall (20).
Figures 6-9 are views that schematically illustrate the irreversible compression deformation of an impact absorbing unit (1) following the fall of a mass (M).
It is specified that in figures 6-9 the mass (M) has been illustrated in a schematic way and, with reference to the rockfall protection gallery (G), the surface of the roof (G1) of the rockfall protection gallery (G) has been illustrated in contact with the impact absorbing unit (1).
Further, the figures relate to tests, simulating the fall of a mass (M) on an impact absorbing unit (1) according to the embodiment of figure 3, i.e. with the impact absorbing unit (1) comprising 7 columns (2), each comprising: 8 collapsible tubular elements (3) and 7 connecting elements (4).
The value of the distance between two connecting elements (4a, 4b) consecutive to one another in a same column (2) has been established at 260 mm, while the value of the transversal section (S) of the tubular element (3a) has been established at 290 mm.
Further, the value of the thickness of the half-shell (11) of each collapsible tubular element (3a) has been established as 2 mm.
These values are chosen so as to be related to one another to determine a folding process, i.e. an irreversible compression deformation of the collapsible tubular element (3a) which leads to collapse thereof, and therefore a crushing thereof, along the relative extension axis (X) when the collapsible tubular element (3a) is subjected to an axial force having an intensity that is at least equal to a critical force value.
It is specified that the values established have been reported by way of example and have been determined using simulation software available on the market. Both the collapsible tubular elements (3) and the connecting elements (4) are made of a metal material.
Further, the impact absorbing unit (1) comprises 3 cables (8) made of a metal material and distanced from one another.
The tests carried out were done by simulating the fall of a mass (M) at a height of 6.70 mm and arranging the impact absorbing unit (1) on a steel plate having a thickness of 50 mm. The steel plate was placed on four load cells with a 30 t capacity to detect the overall force transmitted to the load cells following the fall of the mass (M).
The tests demonstrated that with the impact absorbing unit (1) of the present invention there are no drawbacks as in the prior art linked to the phenomenon of dynamic amplification and have shown that the overall force transmitted to the rockfall protection gallery (G), following the fall of the mass (M), depends on the structure of the impact absorbing unit (1) and assumes values that are comparable to the values of the overall force determined by the deceleration of the mass (M) on the rockfall protection gallery (G).
This technical effect can be observed in figures 11 and 12.
Figure 11 illustrates a graph that reports the trend over time (along the X-axis) of the value of the overall force (along the Y-axis) determined by the deceleration of the mass (M) on the rockfall protection gallery (G), in other words the value of the force exerted by the mass (M) on the rockfall protection gallery (G) calculated by means of the product of the mass of the mass (M) for the relative deceleration velocity.
Again with reference to figure 11, the unbroken line reports the values calculated using a numeric simulation, while the broken line reports the values calculated experimentally, as described in the foregoing.
Figure 12 illustrates a graph that reports the trend over time (along the X-axis) of the value of the overall force (along the Y-axis) transmitted to the rockfall protection gallery (G), in other words the overall force calculated by the sum total of the values acquired by the load cells.
Again with reference to figure 12, the unbroken line reports the values calculated using a numeric simulation, while the broken line reports the values calculated experimentally, as described in the foregoing.
The following contains a description of the use of an impact absorbing unit (1) of a rockfall protection gallery (G) according to any one of the embodiments described in the foregoing, in order to protect a rockfall protection gallery (G) from a mass (M) falling onto the rockfall protection gallery (G).

Claims

An impact absorbing unit (1) of a rockfall protection gallery (G), wherein:
it comprises a plurality of columns (2) which are arranged flanked to one another;

each column (2a) of the plurality of columns (2) comprises: a plurality of collapsible tubular elements (3); a plurality of connecting elements (4) for connecting the collapsible tubular elements (3) to one another;

each collapsible tubular element (3a) of the plurality of collapsible tubular elements (3) comprises an end edge (5);

each connecting element (4a) of the plurality of connecting elements (4) comprises a first face (6) and a second face (7), opposite the first face (6), and is fixed to two collapsible tubular elements (3a, 3b) of a same column (2a) of the plurality of columns (2), which are consecutive to one another;

the impact absorbing unit (1) is configured in such a way that, during use, at least a part of the collapsible tubular elements of the plurality of collapsible tubular elements (3) deforms in an irreversible way, by effect of the compression determined by an axial force exerted by a mass (M) falling on the rockfall protection gallery (G);

the impact absorbing unit (1) of a rockfall protection gallery (G) is characterized in that:
each collapsible tubular element (3a) of the plurality of collapsible tubular elements (3) has a length (L) and a transversal section (S) which are inter-related in order to determine a folding process, i.e. an irreversible compression deformation of the collapsible tubular element (3a) which leads to collapse thereof, and therefore a crushing thereof, along the relative extension axis (X) when the collapsible tubular element (3a) is subjected to an axial force having an intensity that is at least equal to a critical force value;

the end edge (5) of a collapsible tubular element (3a) of the two collapsible tubular elements (3a, 3b) is fixed to the relative first face (6) and so that the end edge (5) of the other collapsible tubular element (3b) of the two collapsible tubular elements (3a, 3b) is fixed to the relative second face (7).
The impact absorbing unit (1) of a rockfall protection gallery (G) of the preceding claim, comprising maintenance means (13) for maintaining the columns of the plurality of columns (2) near to one another.
The impact absorbing unit (1) of a rockfall protection gallery (G) of the preceding claim, wherein the maintenance means (13) comprise at least a cable (8) which winds about the plurality of columns (2).
The impact absorbing unit (1) of a rockfall protection gallery (G) of any one of the preceding claims, wherein: each column (2a) of the plurality of columns (2) comprises a first terminal element (14) and a second terminal element (15).
The impact absorbing unit (1) of a rockfall protection gallery (G) of any one of the preceding claims, wherein the end edge (5) of the collapsible tubular element (3a) is entirely in contact with the first face (6) of the connecting element (4a) and the end edge (5) of the other collapsible tubular element (3b) is entirely in contact with the second face (7) of the connecting element (4a).
The impact absorbing unit (1) of a rockfall protection gallery (G) of any one of the preceding claims, wherein: each collapsible tubular element (3a) of the plurality of collapsible tubular elements (3) externally forms a wall (16) having a plurality of faces (17); the faces of the plurality of faces (17) are adjacent to one another and intersect one another identifying corresponding edges (18).
The impact absorbing unit (1) of a rockfall protection gallery (G) of any one of the preceding claims, wherein each collapsible tubular element (3a) of the plurality of collapsible tubular elements (3) has a polygonal transversal section.
The impact absorbing unit (1) of a rockfall protection gallery (G) of any one of the preceding claims, wherein each connecting element (4a) of the plurality of connecting elements (4) has a planar extension so as to extend internally of the transversal section (S) of each collapsible tubular element (3a) of the plurality of collapsible tubular elements (3).
The impact absorbing unit (1) of a rockfall protection gallery (G) of any one of the preceding claims from 2 to 7, wherein the maintenance means (13) are made of a metal material.
The impact absorbing unit (1) of a rockfall protection gallery (G) of any one of the preceding claims, wherein each connecting element (4a) of the plurality of connecting elements (4) comprises a plate (19).
The impact absorbing unit (1) of a rockfall protection gallery (G) of any one of the preceding claims, wherein each collapsible tubular element (3a) of the plurality of collapsible tubular elements (3) is made of a metal material.
The impact absorbing unit (1) of a rockfall protection gallery (G) of the preceding claim, wherein each collapsible tubular element (3a) of the plurality of collapsible tubular elements (3) is entirely made of a metal material.
The impact absorbing unit (1) of a rockfall protection gallery (G) of claim 11 or 12, wherein each connecting element (4a) of the plurality of connecting elements (4) is fixed by welding to the collapsible tubular elements (3a, 3b) of the plurality of collapsible tubular elements (3), which are consecutive to one another, of a same column (2) of the plurality of columns (2).
A rockfall protection gallery comprising: a plurality of impact absorbing units (110) according to any one of the preceding claims; a containing wall (20) which is arranged, during use, so as to delimit a road and define with the road a passage channel (22).
Use of an impact absorbing unit (1) of a rockfall protection gallery (G) according to any one of claims from 1 to 13, in order to protect a rockfall protection gallery (G) from a mass (M) falling onto the rockfall protection gallery (G).