WO2006035118A1

WO2006035118A1 - Device and method for protecting an elongated object against external blasting

Info

Publication number: WO2006035118A1
Application number: PCT/FR2004/002423
Authority: WO
Inventors: Charles Laubie
Original assignee: Sema
Priority date: 2004-09-24
Filing date: 2004-09-24
Publication date: 2006-04-06

Abstract

The inventive modular device for protecting an elongated object (2) comprises at least one sub-assembly (15, 20, 25) which is provided with two corrugated sheets (5, 6) fixed to each other, wherein said sub-assembly has a domed rounded shape provided with a generally concave opposite surface (11) and the device comprises an energy dissipating structure which is disposed between the concave and convex surfaces in such a way that the elongated object is protected against an external blasting.

Description

Device and method for protecting an elongated object against an external explosion

The invention relates to a device and a method for protecting an elongated object, in particular a pipe, against an external explosion.

Today, a new threat is emerging. People equipped with vehicles loaded with several hundred kilograms of explosives approach installations and cause explosions of a level previously known only in wartime. Network installations such as railways, power grids and pipelines are particularly targeted during wartime. However, the wartime response is to suppress the source of the explosion or to provide alternatives. The protection of all networks and elongated objects has not been sought until now in time of war.

Among these elongated objects, the pipelines were considered sufficiently resistant to everyday impacts, such as falling rocks. Thousands of kilometers of pipelines exist on the surface in the countryside without any protection.

A new need appears. Elongated objects must be protected against an external explosion.

Concrete segments are commonly used, assembled together to form a tunnel. However, this type of solution is too expensive.

The invention provides a protection for elongated objects, such as a pipe, inexpensive, which can be installed by a low - skilled labor force, and light enough for the installation to be carried out by widely used handling or public works equipment. The protection provided by the device makes it possible to reduce the impact of an external explosion.

According to one aspect of the invention, the device is modular and comprises at least one subassembly provided with two corrugated sheets fixed to one another. The subassembly has a curved rounded shape, provided with a generally concave surface to be arranged around the elongated object, and a generally convex surface opposite. The device has an energy dispersing structure between the concave and convex surfaces so that the elongated object is protected against an external explosion.

This provides a cheap and lightweight protection. The fact that the device is modular allows for on-site installation. The dissipative structure of the energy in association with the sheets protects from an external explosion from a wide area as the device surrounds the elongated object.

In a variant, the corrugations of the two sheets of said subassembly are in opposition to one another in order to form a series of parallel volumes surrounded by sheets. Advantageously, said parallel volumes comprise a compressible fluid, such as air for example.

Advantageously, the device comprises a means of obstruction of at least one end of at least one of said parallel volumes.

In a variant, said subassembly comprises a tensile reinforcement between the corrugated sheets, the reinforcement and the sheets being fastened together at least in the vicinity of the ends of the sheets in the direction of the width of the corrugations. In a variant, the device comprises a bent subassembly, the axes of said parallel volumes being arranged in an arc of a circle perpendicular to the bending axis or in a helix around the bending axis. Advantageously, the device comprises at least two subassemblies offset radially with respect to the axis of the bending, and fixed to one another, the undulations in contact with each other being in opposition to each other. that the space between said subsets forms a series of parallel volumes. Advantageously, the two subassemblies are offset axially along the bending axis by a distance corresponding to an integer number of corrugations.

Advantageously, the device comprises fixing means with another identical device, on each side of the device along the bending axis, so that the device is modular and that its assembly can take place near the object to protect .

Advantageously, a ballistic protection element is inserted between the convex and concave surfaces of the device.

Advantageously, the device comprises an angle at at least one of the ends of the sheets of said subassembly in the direction of the length of the corrugations. The angle allows in particular to fix the plates between them, or to obstruct the end of the parallel volumes of the subassemblies. The angle can also serve as a guide to the assembly of the modular device and also makes it possible to reduce the risk of cutting the person who assembles the device or to protect the edges of the device against handling shocks.

According to another aspect of the invention, the method of protecting an elongated object comprises a step of laying and assembling voussoirs over an elongated object, including a pipe, deposited in trench, and a step of covering said voussoirs by filling the trench. Such a process makes it possible to hide the object to be protected and to make that an external explosion will be localized with me ns of acuity and thus reduces the probability of damage.

According to another aspect of the invention, the method of protecting an elongate object comprises a step of laying and assembling voussoirs over an elongated object, in particular a pipe, a step of laying segments at below said elongated object, and a step of assembling the segments below with those of above. Such a method can protect an elongated object such as an existing pipe without cutting the pipe, or interrupt the operation of this pipe.

Other characteristics and advantages of the invention will become apparent on reading the detailed description of some embodiments given by way of nonlimiting examples illustrated by the appended drawings in which:

- Figure 1 is an axial schematic view of a first embodiment of the invention showing a voussoir shape; Figure 2 is a sectional view of another embodiment along the line II-II of Figure 1;

- Figure 3 is a sectional view along the axis III-III of Figure 1; Figure 4 is a schematic axial sectional view of the assembly of a voussoir from above and a voussoir from below;

- Figure 5 is a schematic plan view of a second embodiment; and Figure 6 is a schematic sectional view of a third embodiment of the invention.

In a conventional manner, the parts of the figures corresponding to the positive X's will be called "right", those corresponding to the negative X's will be called "left", the parts corresponding to the positive Y's will be said "upwards", those to the negative Y's will be said "Down", those with positive Z will be called "downstream" and those with negative Z will be called "upstream".

As illustrated in Figures 1 to 3, the device 1 for protecting an elongated object 2, for example a pipeline, may be covered with material 2a, for example earth, and has a general shape of vault forming a voussoir. The device 1 comprises an inner assembly 3 and an outer assembly 4 provided with one and the other of a stack of corrugated sheets. The inner assembly 3 comprises corrugated sheets 5 and 6. The outer assembly 4 comprises corrugated sheets 7, 8, 9 and 10. The corrugated sheets 5, 6, 7, 8, 9 and 10 are bent around a Z axis perpendicular to the corrugations of each of the corrugated sheets. Thus each sheet appears in Figure 1 only by an inner and outer surface. The sheet 5 has an outer surface 11 and an inner surface 12. The sheet 6 has an outer surface

13 and an inner surface 14. The inner surfaces 12 of the sheet 5 and outer 13 of the sheet 6 are in contact and fixed to each other so as to form a sub-assembly 15. The sheets 5 and 6 are over most of their length, for example over 90%. The subassembly 15 has a domed and rounded shape, with a generally concave surface 14 disposed around the elongated object 2, and a generally convex surface 11 opposite. Similarly, the sheet 7 has an outer surface 16 and an inner surface 17. The sheet 8 has an outer surface 18 and an inner surface 19. The surfaces 17 and 18 are in contact and fixed to each other so that that sheets 7 and 8 form a subassembly 20. Similarly, the sheet 9 has an outer surface 21 and an inner surface 22. The sheet 10 has an outer surface 23 and an inner surface 24. The surfaces 22 and 23 are in contact and fixed to one another so that the plates 9 and 10 form a subassembly 25. The outer assembly 4 consists of the two subassemblies 20 and 25 which are fixed together, the surface 19 and the surface 21 being in mutual contact. The outer assembly 4 may comprise any number of subassemblies. Similarly, the inner assembly 3 has only one subassembly 15, in the illustrated embodiment, but could have two or more.

The longitudinal ends of the plates 5 and 6 are assembled by an angle iron 26 on the right side and by an angle iron 27 on the left side. The two angles 26 and 27 ensure the cohesion of the ends of the inner assembly 3. Similarly, the cohesion of the outer assembly 4 is provided by brackets 28 and 29. The cohesion of the outer assembly 4 is also ensured in that the inner surface 19 of the subassembly 20 and the outer surface 21 of the subassembly 25 are in contact and can be fixed to each other. Similarly, the inner and outer assemblies 3 and 4 are attached to each other in that the inner surface 24 of the assembly 4 and the outer surface 11 of the assembly 3 are in contact and can be fixed to each other. to one another over most of their length except at their ends where there is a space 30 and 31 to leave room for angles 27 and 28. The two sets 3 and 4 are radially offset, one being inside, the other outside the device as well as angularly. The angle 26 is lower than the angle 28. Conversely, the angle 27 is higher than the angle 29. The relative angular position of the inner 3 and outer 4 assemblies is such that the height difference to the right and left are identical. When the assembly 1 rests on the ground, it bears on the angle iron and on the angle iron 26. Thus, the ends of the corrugated sheets are protected against errors in the handling of the device 1. The device has a curved rounded shape with a generally concave surface 14 disposed around the elongate object 2 and a generally convex surface 16 which will be exposed more directly to the impacts of the explosion whose object 2 is to be protected.

In a variant, the height offset of the ends of the inner assembly 3 and the outer assembly 4 is zero. This variant is particularly suitable when the device is intended to be buried. This variant has the advantage of increasing the support surface on the ground during storage, during handling, or in use.

As seen in Figure 2, the sheets 5, 6, 7, 8, 9 and 10 have parallel corrugations, stacked in opposition to one another and thus forming a honeycomb structure. The honeycomb structure is equipped with a traction reinforcement. Sheet 27 has valleys 32 and sheet 8 has peaks 33.

The valleys 32 and the vertices 33 are in contact along a series of contact lines 34, in an arc. Rivets 35 are distributed on the contact lines 34 and fix the plates 7 and 8 to each other, so that that the subset 20 is rigid. The contact lines 34 define a series of parallel volumes 36 surrounded by sheets. The volumes are bent in the shape of a circular arc.

The sheet 9 of the subassembly 20 also has valleys 37 and the sheet 10 has peaks 38. A traction reinforcement 39 in the form of a flat sheet matches the generally rounded shape of the subassembly 20, as illustrated in section. in Figure 2. The tensile reinforcement 39 is sandwiched between the plates 9 and 10. The peaks 37 and the valleys 38 are in contact with the tensile reinforcement sheet 39 and coincide to form a series of lines contact 40 in an arc.

Rivets 41, 42, 43 are distributed over the contact lines 44 situated on the sides of the corrugated sheets 9 and 10. The sheets 9 and 10 are fixed together and with the tensile reinforcement 39, in the vicinity of the ends of the sheets in the direction of the width of the corrugations, by the rivets 41, 42, 43. The tensile reinforcement sheet 39 is stretched between the end fixing points 41, 42. The contact lines 40 define a series of parallel volumes 45, traversed by the reinforcement 39, surrounded by sheets and curved in the shape of an arc. The tensile reinforcement 39 opposes the flattening of the corrugations. The two subassemblies 20 and 25 are assembled separately at the factory and then stacked one on the other by fasteners 46.

The two subassemblies 20 and 25 are radially offset and their assembly keeps in contact opposite corrugations of the sheets. Thus, volumes 47 are isolated and parallel to each other. The volumes 36 and 45 of the subassemblies as well as the volumes

47 between two subsets are rounded in the shape of an arc around the axis Z which is the bending axis of the sheets. The subassembly 15 has a structure identical to that described for the subassembly 20.

The fastener 46 positions the subassembly 15 so that all the sheets taken as a whole form a honeycomb structure. The alignment of the subassemblies between them and assemblies between them may be provided by other positioning means such as bolts or angles.

The honeycomb structure is particularly effective in dissipating the energy of a blast effect from an explosion that propagates in the form of a mechanical compression wavefront. The alveolar structure flattens under the effect of compression. Tensile reinforcement

39 increases the stiffness of the honeycomb structure. Likewise, the fact that the angles 26, 27, 28, 29 close off the air volumes 36, 45,

47 allows to take advantage of the compressibility of the air and to make these volumes have their own stiffness. The tensile reinforcement 39 may be a wire mesh, or transverse flat bars with respect to the corrugations.

The reinforcement may also be of ballistic aramid, which allows the device to have a high bursting property that the corrugated sheet would not have taken alone. Indeed, if a bullet enters the device, it passes through the sheets to the ballistic aramid reinforcement which is then strongly stressed and in turn pulls on the honeycomb structure. Thus, the energy of the ball is dissipated by the entire honeycomb structure, which stops the ball. It is the same for exploding explosives.

FIG. 3 illustrates how the device 1 is modular and will be able to be coupled with another device 1a located downstream and already installed. The angle 27 extends over the entire width of the inner assembly 3. It is the same for the right angle 26.

On the other hand, the left-hand angle 29 of the outer assembly 4 extends over a portion 47 of the sub-assembly 25 and protrudes therefrom by a portion 48 of length equal to the axial offset of an assembly relative to the other. It is the same for the right angle 28 which protrudes from the outer assembly 4 on a portion 50 of length equal to the axial offset of the two sets 3 and 4.

The downstream device already installed also has an angle bracket 29a of which a portion 48a is free and will be able to receive the portion 49 of the outer assembly 4 without bracket 29. Also on the right edge, an angle of the device la, similar at the angle 28 of the device 1 surrounding the assembly 4a protrudes from a portion similar to the portion 50 of the bracket 28 and will be able to receive the portion 51 of the outer element 4.

Angles 28 and 29 are U-shaped, making them very effective guide rails for assembling two devices. Thus, once threaded into the portion 48 of the bracket 29a of a downstream device 1a, a light 52 of the outer assembly 4 will coincide with a light 53a of the downstream device 1a. Similarly, a light 54 of the outer assembly 4 will coincide with a light 55a of the downstream device 1a. The attachment can then be carried out simply by bolts or other fastening device.

The two sets 3 and 4 are axially offset by an integer number of corrugations.

Figure 4 illustrates how two devices 1 and the same can be assembled one above the other. The height difference between the angles 26 and 28 being equal to the offset in height between the angles 27 and 29, a simple rotation of a half - turn of the device around the Z axis makes it possible to match the complementary shapes of the devices 1 and 1a. Thus, the angle 28 is opposite the bracket 29a, the angle 26 facing the bracket 27a. Similarly, the bracket 27 of the device 1 is opposite the bracket 26a of the device la and the bracket 29 opposite the bracket 28a of the device la.

In a particular embodiment, the device uses eight corrugated sheets whose corrugations are separated by 76 mm and have an amplitude of 18 mm, the width of the corrugated sheet is 890 mm and the unfolded length of the corrugated sheet used for this purpose. device is two meters. Thus, once assembled, the outer assembly comprises two subsets of two sheets and the inner assembly also includes two subsets of two sheets. The bending form is an arc of a circle with a height of about 770 mm. The axial offset between the outer assembly and the inner assembly is 152 mm. The inside diameter is substantially 1.25 meters and the outside diameter less than 1.55 meters.

Tests were carried out to protect an 11 mm pipeline portion of pipe sparer. A voussoir according to the particular embodiment surrounds the pipeline. The load was placed in contact with the voussoir. The explosion did not damage the pipeline, while without the protective device, the same charge sprayed the wall of the same pipeline.

The means of obstruction of the air volumes can be achieved by flattening the ends of the two sheets of the same subassembly and fixing or riveting them to one another.

Figure 5 shows a second embodiment where corrugated sheets are stacked on each other helically. Sheet metal corrugated are inclined relative to the Z axis of a helix angle α, a sheet 56 is supported on a sheet 57, the valleys 58, 59, 60 of the sheet 56 are in contact with the vertices 61, 62, 63, 64 of the sheet 57. The two sheets are supported by a multitude of points 65, 66 through which the sheets 20 can be fixed to one another and together form a sandwich capable of dissipating the energy.

In FIG. 6, corrugated sheets 67 and 68 sandwich another corrugated sheet 69 with the same pitch but of smaller amplitude. The set of three sheets forming a subset fixed at points 70 and 71 near the ends in the direction of the width of the corrugations. In another variant, the sheet 69 is a flat plate sandwiched between two identical corrugated sheets. Such a structure is capable of dissipating energy, for example by being flattened.

Claims

Protective device for an elongate object (2), in particular a pipe, characterized in that it is modular and comprises at least one subassembly (15, 20, 25) provided with two corrugated sheets ( 5,6) fixed to each other, the subassembly having a rounded curved shape with a generally concave surface (14) to be arranged around the elongate object (2), and a surface generally convex opposite (1 1), the device having between the concave and convex surfaces a dissipative energy structure so that the elongate object is protected against an external explosion.

2. Device according to claim 1 characterized in that the corrugations of the two sheets of said subassembly are in opposition to each other to form a series of parallel volumes (36) surrounded by sheets, said two sheets overlapping in part.

3. Device according to claim 2 characterized in that said parallel volumes comprise a compressible fluid.

4. Device according to any one of claims 2 to 3 characterized in that it comprises means for obstructing (26) at least one end of at least one of said parallel volumes.

5. Device according to any one of claims 2 to 4 characterized in that said subassembly comprises a tensile reinforcement (39) between the corrugated sheets (9, 10), the reinforcement and the plates being fixed together at least to near the ends of the sheets in the direction of the width of the undulations.

6. Device according to any one of claims 2 to 5 characterized in that it comprises a bent sub-assembly, the axes said parallel volumes being arranged in the shape of a circular arc perpendicular to the bending axis or in a helix around a bending axis.

7. Device according to any one of claims 1 to 6 characterized in that it comprises at least two subsets

(20,25) offset radially with respect to the axis of the bending, and fixed to one another, the undulations in contact with each other being in oppositions so that the space between said subsets form a series of parallel volumes.

8. Device according to claim 7 characterized in that said two subsets (15,20) are offset axially along the axis of bending by a distance corresponding to an integer number of corrugations.

9. Device according to any one of claims 1 to 8 characterized in that it comprises fixing means (52a, 53a) with another identical device (la), each side of the device along the axis bending.

10. Device according to any one of claims 1 to 9 characterized in that a ballistic protection element (39) is inserted between the convex and concave surfaces.

11. Device according to any one of claims 1 to 10 characterized in that it comprises an angle bracket (26) attached to at least one end of the laminations of said subassembly in the direction of the length of the corrugations.

12. A method of protecting an elongate object comprising a step of installing and assembling voussoirs over the elongate object, including a pipe, deposited in trench, and a step of covering said voussoirs by plugging the trench.

13. A method of protecting an elongated object comprising a step of laying and assembling voussoirs over an elongate object, including a pipe, a segmenting step beneath said elongate object, and a step assembly of voussoirs from below (la) with those from above (1).