EP0928947B1 - Opto-pyrotechnic demolition application of an installation. - Google Patents

Abstract

Explosives are detonated by outputting a laser signal through fiber optic circuits to the detonators, providing secure and individual firing.

Description

Technical area

The invention relates to an installation designed to ensure demolition or destruction, using explosives, constructions such as buildings, industrial buildings, engineering structures, rocks and generally any structure natural or having been the subject of an edification preliminary (buildings, public works, works underground, quarries, etc.).

State of the art

When constructions, structures, materials, etc. are destroyed with explosives, a large number of small explosive charges is placed in holes drilled in the structures of the works to demolish.

Currently, these small charges are initiated by medium or high electric detonators intensity, which are ignited electrically using of blasting.

More specifically, in order to limit nuisance such as vibration, breath, noise, etc. the global explosion is broken down into a multitude of small explosions spaced apart in time.

For this purpose, we usually use electric micro-delay detonators, grouped by series (for example of twenty units). Spacing over time (e.g. 25 thousandths of a second) is provided between each detonator of the same series.

Explosives are also usually used sequential, ensuring the ignition of several detonator lines spaced over time. Several sequential exploders can then be mated.

When they are intended to ensure the demolition of an apartment building, the existing installations operating on this principle include 1500 to 2000 detonators per shot. Due to spacing of explosions triggered by installation, the shot can last up to 3 to 4 seconds. This shot follows mining work and priming which can last 3 to 4 days, even a week.

With current installations, primers nuisance or damage may occur during the entire duration of the preliminary mining work and boot.

The main risk of untimely priming results from stray currents that may occur around the initiated charges. These stray currents can have different origins such as the lightning, and currents from networks electrical overhead or located in the ground, currents from neighboring electrical installations in service (electrical transformers, catenary lines of railways or trams, lighting lamps etc.) and the natural currents flowing underground in the case of tunnel drilling.

Unintentional ignition of charges can also originate from the use of devices electronics such as radios, walkie-talkies, cell phones, etc. close to these loads.

An inadvertent firing of detonators may also occur during transport or during storage, for example due to stray currents or accidents of various origins.

Since the mining works can last 3 to 4 days or even a week, there are also a risk that previously charges installed are intentionally ignited, using a simple electric battery or a drums.

On the other hand, when the building to be demolished concerns the nuclear industry, as is notably the case for the demolition of a nuclear power plant, the existing fired demolition facilities cannot be used, given the disturbances that exist in a radioactive medium intense.

The existing demolition facilities in electric fires are also prone to failures that can affect the demolition work. These failures are mainly caused by sons cut or in contact with earths metal such as protective mesh, metallic equipment of buildings to be demolished, etc. When the building to be demolished is an important metal structure such as a thermal power plant, failures can also originate from fields electrics produced by the huge mass of scrap metal building.

In addition, the electric detonators used in existing demolition facilities can be stolen and easily reused as well when their transport or their storage only after their placing in place in the building to be demolished.

Finally, it should be noted that when such a demolition facility has anomalies in circuits, these anomalies are very long and dangerous to detect. Indeed, if it is possible to find out which line is faulty, the exact location of the rupture of the circuit, cannot be known with precision.

Document US-A-5 206 455 describes a system able to destroy a launcher in the event of a malfunction. Laser diodes or bar laser sources pumped solids are used to ignite pyrotechnic charge initiators, through fiber optic cables.

Document US-A-5 031 187 proposes to carry out a planar array of laser diodes arranged in a matrix, so that they can be ordered selectively.

Exhibition of the invention

The subject of the invention is precisely a demolition facility, whose original design allows it to remove all the disadvantages of existing electrical installations, in eliminating in particular any risk of accidental ignition or malicious, both during work mining and priming than during storage and prior transportation of the system components, when said installation is applied to the demolition of buildings or natural structures.

• une centrale de commande à plusieurs sorties, comportant au moins une source laser et au moins un interrupteur de commande de ladite source laser, dont une fermeture provoque l'émission, par la source laser, d'un premier faisceau laser à au moins l'une desdites sorties ;
• des initiateurs pyrotechniques à commande optique, disposés en des emplacements déterminés d'une structure à détruire ; et
• des fibres optiques reliant chacun des initiateurs pyrotechniques à l'une des sorties de la centrale de commande.

According to the invention, this result is obtained by means of an application to the demolition of buildings or natural structures, of an installation comprising at least two independent groups of components, each including:

• a central control unit with several outputs, comprising at least one laser source and at least one switch for controlling said laser source, the closure of which causes the emission by the laser source of a first laser beam at at least the one of said outputs;
• optically controlled pyrotechnic initiators, arranged in determined locations of a structure to be destroyed; and
• optical fibers connecting each of the pyrotechnic initiators to one of the outputs of the control unit.

In an installation thus designed, the fire of the pyrotechnic initiators takes place only optically through fibers optics. This firing is therefore totally insensitive to stray currents. This provides a optimal safety, especially when construction demolish is located in or near posts electrical, or under catenary lines. Else apart, a stormy weather has no influence on progress and safety of works.

The aforementioned characteristic also makes it possible to safely demolish buildings located in large urban centers despite the large number of electronic devices present in these centers.

In addition, a firing started by malicious people is excluded because it would that these people have a laser and that this one compatible with the precise frequency of the laser employed in the installation.

Since the firing control is done optically, no metallic mass may disrupt priming. Security during transport and during storage of the components is also insured.

In addition, detonators with optical control do not can be used in case of theft.

Finally, a calculator makes it possible to determine easily the place of a possible break in the optical fiber.

In a first embodiment of the invention, laser sources are rod sources solid pumped, operating in relaxed mode. Each plant control unit then includes a single laser source and a first optical splitter coupler having a primary optical input capable of receiving the beam laser emitted by the laser source and several outputs forming the outputs of the control unit.

In each group, at least some of the optical fibers then connect several initiators pyrotechnics at one of the central power station exits control through at least a second coupler optical divider.

Advantageously, each control center includes a secondary optical input and first return means capable of directing towards the entrance of the first optical splitter coupler an additional laser beam entering the control unit by its secondary optical input. An additional laser source common to all groups is then provided, so as to emit the additional laser beam, when necessary as a result of a laser source failure at one of the plants control.

Each control unit can also include an auxiliary control input and second return means, capable of establishing a route derivative optics between the auxiliary control input and the input of the optical splitter coupler of this central control. This arrangement makes it possible in particular to control the integrity of optical fibers by means of a visible light source placed in front of the entrance control assistant.

Each control unit includes this preferably a retractable shutter capable of being placed between the laser source and the input of the splitter coupler optical.

The second return means are formed on this retractable shutter, when the latter occupies a active shutter position.

Each control unit can also include a standard safety switch with the laser source control switch.

In a second embodiment of the invention, the laser sources are laser diodes. Each control unit then includes as many laser diodes as outputs and each laser diode is optically connected to one of these outputs.

In this second embodiment of the invention, each of the laser diodes can be mounted in series with a separate control switch in each of the control units. In this case, a common safety switch is fitted in series with all the laser diodes of each control unit.

As a variant, in each of the control units, the laser diodes form a matrix of n rows and m columns, the laser diodes of each line being connected in series with a first control switch and the outputs of the laser diodes of each column being connected to a second control switch.

Brief description of the drawings

• la figure 1 représente schématiquement une installation de démolition de constructions, illustrant une première forme de réalisation de l'invention ;
• la figure 2 représente schématiquement les éléments constitutifs de l'un ces blocs de commande de l'installation de la figure 1 ;
• la figure 3 est une vue schématique comparable à la figure 1, illustrant une deuxième forme de réalisation de l'invention ;
• la figure 4 est une vue qui représente schématiquement une première réalisation possible d'une centrale de commande dans l'installation de la figure 3 ; et
• la figure 5 est une vue comparable à la figure 4, illustrant schématiquement une variante de réalisation d'une centrale de commande équipant l'installation de la figure 3.

Various embodiments of the invention will now be described, by way of nonlimiting examples, with reference to the appended drawings, in which:

• Figure 1 schematically shows a building demolition installation, illustrating a first embodiment of the invention;
• FIG. 2 schematically represents the constituent elements of one of these control blocks of the installation of FIG. 1;
• Figure 3 is a schematic view comparable to Figure 1, illustrating a second embodiment of the invention;
• Figure 4 is a view which schematically shows a first possible embodiment of a control unit in the installation of Figure 3; and
• FIG. 5 is a view comparable to FIG. 4, schematically illustrating an alternative embodiment of a control unit equipping the installation of FIG. 3.

Description of preferred embodiments of the invention

In the first embodiment of the invention illustrated in FIGS. 1 and 2, the demolition facility includes several groups completely independent, each comprising a control center 10 a number pyrotechnic initiators 12 with optical control, as well as optical fibers 14 connecting each of the pyrotechnic initiators 12 at one of these outputs 18 of the control unit 10 of the corresponding group.

In Figure 1, only two are shown independent groups of a demolition facility according to the invention. In practice, the number of installation independent groups is not limited and can be any number greater than or equal to 2. By convention, we call K the number of groups independent of the installation.

Each of the control units 10 comprises in this case a single laser source 16, constituted by a laser source with a solid pumped rod, operating in relaxed mode, i.e. without triggering at using Pockels cells or any other means similar. The characteristics of such a source laser are those of a relatively pulse train long (about 150 µs), capable of delivering a instantaneous power of the order of a few tens optical kilowatts.

This power level of laser sources 16 allows the laser beam to be divided, successively inside each control center 10, then possibly downstream of this plant.

Inside each of the command 10 and as illustrated more specifically the Figure 2, the division of the laser beam is ensured by a first optical splitter coupler 22. This first optical splitter coupler 22 has an input single, located on the optical path of the laser source 16, so as to receive the laser beam emitted by this source. The optical splitter coupler 22 includes also N outputs forming the outputs 18 of the control unit 10.

In practice, the number of exits 18 from each of the control units 10 is understood, by example, between four and twelve. It should be noted that the number of outputs 18 of control units 10 of each group can be the same or different from one group to another, without going outside the framework of the invention.

As shown schematically and only partially in Figure 1, the optical fibers 14 allow each of the outputs 18 of the control units 10 as the case may be one or more of the pyrotechnic initiators 12 of the group considered.

So, we represented at the top of the FIG. 1 the case of a pyrotechnic initiator 12 of which the optical input is connected directly to one of these outputs 18 of the corresponding control unit 10 by an optical fiber 14, without any organ being interposed on the path of the optical fiber.

On the contrary, all the other links represented between the outputs of the control 10 and the optical inputs of the initiators pyrotechnics 12 are designed to connect several pyrotechnic initiators 12 to the same output 18. For this purpose, the outputs are interposed 18 concerned and the initiators 12 scheduled to be connected to these outputs of the second dividing couplers optics 20.

More specifically, each of the second optical splitter couplers 20 has one input single, which is connected to one of the outputs 18 of the corresponding control center 10 by a first fiber optic 14, as well as several outputs each of which is connected to one of the pyrotechnic initiators 12 by a corresponding optical fiber 14.

The second optical splitter couplers 20 used in the installation can be all identical or different types. Their number of outputs is for example, between 4 and 12.

By choosing the number of outputs splitter couplers 22 and 20, we must ensure that the power and energy supplied to each of the pyrotechnic initiators 12 is sufficient to ensure ignition. Indeed, the power and the energy supplied depend on the characteristics of the laser source 16 contained in the central command 10 and the total attenuation arising from the cascading of several splitter couplers on the or the routes considered.

• PS représente la puissance délivrée par la source laser (en dB_ω) et
• Σ représente la somme des pertes imputables à la liaison optique et aux coupleurs optiques.

This observation is confirmed by the approximate expression of the power PD (in dB _ω ) available for any initiator 12, which is given by the following formula, in the case of a group comprising a control unit with N outputs 18 and a second optical divider cutter 20 with M outputs interposed between one of the outputs of the control unit 10 and the pyrotechnic initiator 12 considered: PD = PS + 10 log 1 NOT + 10 log 1 X + Σ, or

• PS represents the power delivered by the laser source (in dB _ω ) and
• Σ represents the sum of the losses attributable to the optical link and to the optical couplers.

The pyrotechnic initiators 12 are optically controlled detonators, capable of controlling the initiation of explosive charges placed in holes drilled in the structures of the structure to demolish. Optically controlled detonators can be constituted as appropriate either by detonators to classic delays to which an entry has been adapted optical, either by existing opto-detonators designed for the space industry such as those who are described, for example, in documents FR-A-2 615 609 and FR-A-2 646 901.

In the architecture of the installation of demolition thus conceived, all the initiators of the same group are ignited simultaneously. On the other hand, independence between groups allows them order separately with scheduled delays. Of even, it is thus possible to ensure redundancy pyrotechnic initiators by placing in neighboring locations of the initiators belonging to different groups.

As Figure 2 illustrates more specifically, each of the control units 10 comprises a laser source power supply circuit 16. This electrical supply circuit comprises, in series between an input connector able to be connected to an external source (not shown) and the source laser 16, a safety switch 24, a low voltage / high voltage converter 26, as well a switch 28 for controlling the laser source 16. When this supply circuit is connected to the external electrical power source, setting work of the laser source 16 supposes the closing of each of switches 24 and 28.

The laser beam emitted by the laser source 16 during its implementation is transmitted to the input of the optical splitter coupler 22 by an optical adaptation 30.

Upstream of the adaptation optics 30, a retractable shutter 32 is placed on the way optic which connects the laser source 16 to the input of the optical splitter coupler 22. This shutter retractable 32 is controlled by a motor 34 which allows to move it between a retracted passive position, in which the shutter 32 is not placed on the aforementioned optical path, and an active position shutter, shown in Figure 2, in which the shutter is placed on this optical path.

The retractable shutter 32 and the switch security 24 constitute two security organs eliminating any risk of inadvertent ignition by following an unexpected closing of the command 28.

As shown schematically in Figure 2, the retractable shutter 32 has a face tilted reflective 32a, turned towards optics adaptation 30 when the shutter occupies its position active shutter. This inclined reflecting face 32a of the retractable shutter 32 constitutes means of dismissal, likely to direct towards the entry of optical splitter coupler 22 a light beam entering the control unit 10 through a auxiliary control input (not shown) or, at otherwise, direct to this auxiliary input of controls a light beam coming from one or many of the lines formed by optical fibers 14.

This arrangement makes it possible to control, different ways, the integrity of the installation. Thus, a known, limited power, can be injected by the auxiliary control input. Measurement of the fraction returned on each of the outputs optics can then be compared to the calculation forecast to carry out a first check.

Conversely, the measurement can be carried out in injecting a known power from the end of the supposedly faulty line, using possibly a conventional reflectrometry means placed opposite the auxiliary input. Possible fault can thus be located since each line is independent in the direction of its end towards the control unit 10.

The auxiliary control input can also be used by the operator making the connection these pyrotechnic initiators 12, to verify that it this is the right line, by simple visualization a light source 36 (Figure 2) placed opposite the auxiliary control input and selected in the visible domain.

In addition, each of the control units 10 has a secondary optical input 40 and deflection means for directing a beam additional laser to the input of the splitter coupler optics 22, through the adaptation optics 30, in the case where the laser source 16 of this central command would be faulty.

As illustrated schematically on the Figure 2, the secondary optical input 40 is provided an appropriate adaptation lens and the means to return include a fixed return member such as a mirror 42, as well as a movable deflection member such than a mirror 44.

The movable return member 44 is controlled by a motor 46 which allows it to be moved between a position passive retracted (Figure 2) and a position active. In this latter position, the mobile deflection 44 directs the additional laser beam, which enters the control center 10 by its secondary input 40, towards the input of the splitter coupler optics 22. More precisely, the laser beam additional entering the control unit 10 through secondary input 40 is returned by the device fixed return 42 to the return device mobile 44 and the latter is interposed between the output the laser source 16 and the retractable shutter 32, when placed in its active position.

The entire installation also includes an additional laser source 48 (FIG. 1) common to all groups, and can be used when of a shot if the laser source 16 of one of the central 10 is faulty. To this end, the additional laser source 48 is brought in front of the secondary optical input 40 of the central corresponding command.

We will now describe, with reference to the figures 3 to 5, a second embodiment of the invention.

This second embodiment stands out essentially from the first by the nature of laser sources, which consist of diodes laser 16. Since the power and energy delivered by a laser diode are significantly lower to those issued by a source pumped solid rod laser, as in the first described embodiment, in this case we use a separate laser source for each pyrotechnic initiator 12 and the presence of dividing couplers optics is excluded.

As illustrated in Figure 3, the architecture of the installation remains very close from that described above with reference to the figure 1. Thus, the installation is formed of a certain number of independent groups each comprising a control unit 10 with several outputs 18, pyrotechnic initiators 12, and optical fibers 14 connecting outputs 18 of each central command to the pyrotechnic initiators 12. More specifically, the number of outputs 18 is equal in this case to that of the pyrotechnic initiators 12 and a fiber optics 14 connects each of the outputs individually 18 to one of the pyrotechnic initiators 12.

In the basic solution of this second embodiment of the invention, illustrated in the Figure 4, each of the control units 10 comprises as many laser diodes 16 as outputs 18, the beam laser from each diode being directed towards a corresponding output. In addition, all the diodes laser 16 are electrically connected in parallel in an electrical supply circuit intended to be connected to an external power source low voltage, illustrated at 49 in Figure 3.

More specifically, a control switch 28 is mounted in series on each of the laser diodes 16, upstream of these. In other words, if we designate by N the number of outputs 18 of the central control 10, the electrical circuit includes N branches parallel successively including a switch control 28 and a laser diode 16. Inside the control unit 10, all these branches are connected on a common power line which includes a safety switch 24. Downstream, the different parallel branches are connected on a return line 25 which loops the circuit towards the source low voltage power supply 49.

For each of the laser diodes 16 considered individually, the safety switch 24, the switch 28 corresponding to this diode and the laser diode itself are connected in series.

In the architecture illustrated in Figure 4, each of the laser diodes 16 is controlled so independent by a separate control switch 28. There are therefore as many control switches as pyrotechnic initiators 12 to be ordered. This presents the advantage of authorizing the order of updates completely free fire.

FIG. 5 shows a variant of the second embodiment of the invention, making it possible to reduce the number of control switches 28. In this case, each control unit 10 always comprises as many laser diodes 16 as there are outputs 18. However, instead of being mounted on separate parallel branches in the electrical circuit, the laser diodes 16 are electrically connected together so as to form a matrix of n rows and m columns.

More specifically, the laser diodes 16 of each line are connected in series with a first switch 28a and the outputs of the laser diodes 16 of each column are interconnected and connected to a return line 25 including a second control switch 28b.

In this arrangement, it is possible to order individually the laser diodes 16 of the column leftmost by closing the switch 28a of the corresponding line and switch 28b connected to the output of this column. However, the command individual laser diodes 16 located in the others columns is not possible. So, the command of any laser diode in the array cannot by controlling all the diodes simultaneously laser located on the same line and upstream, that is to say to the left of the laser diode considered on Figure 5.

The arrangement which has just been described with reference in Figure 5, however, has the advantage of significantly reduce the number of switches command, since instead of being equal to the total number diodes (for example, about 100 for each group) it is equal in this case to the sum of the number of rows and number of columns of the diode array laser (for example, about 20).

In the second embodiment which comes to be described with reference to Figures 3 to 5, a suspected failure of one of the lines can be detected from the end thereof, by means of devices this conventional control (reflectrometry, echometry).

Claims (12)

1. Application to the demolition of buildings or natural structures of an installation including at least two independent groups of components, each comprising:

   a control unit (10) with several outputs (18), each comprising at least one laser source (16) and at least one control switch (28) for the said laser source, in which closure will cause the laser source to emit a laser beam at one or more of the said outputs (18);

   optically controlled pyrotechnic initiators (12) placed at determined locations in the structure to be demolished; and

   optical fibres (14) connecting each of the pyrotechnic initiators (12) to one of the outputs (18) of the control unit (10).
2. Application according to claim 1, in which the laser sources (16) are sources with a pumped solid rod, operating in relaxed mode, each control unit (10) comprising a single laser source and a first optical divider coupler (22) with a primary optical input (30) capable of receiving the laser beam emitted by the laser source, and several outputs forming outputs (18) from the control units (10).
3. Application according to claim 2, in which at least some optical fibres (14) in each group connect several pyrotechnic initiators (12) to one of the outputs of the control unit (10) through at least one second optical divider coupler (20).
4. Application according to either of the claims 2 and 3, in which each control unit (10) comprises a secondary optical input (40) and feedback means (42, 44) capable of steering an additional laser beam penetrating into the control unit through its secondary optical input (40), to the primary optical input (30) of the optical divider coupler (22) for this control unit, an additional laser source (48) common to all groups being capable of emitting the said supplementary laser beam.
5. Application according to any one of the claims 2 to 4, in which each control unit (10) comprises an auxiliary control input and second feedback means (32), capable of setting up a bypass optical path between the auxiliary control input and the primary optical input (30) to the optical divider coupler (22) in this control unit.
6. Application according to any one of the claims 2 to 5, in which each control unit (10) comprises a retractable shutter (32) that may be placed between the laser source (16) and the primary optical input (30) to the optical divider coupler (22).
7. Application according to claims 5 and 6 combined, in which the second feedback means are formed on the retractable shutter (32) when the shutter occupies its active closed position.
8. Application according to any one of the claims 2 to 7, in which each control unit (10) comprises a safety switch (24) installed in series with the laser source control switch (16).
9. Application according to claim 1, in which the laser sources are laser diodes (16), each control unit (10) comprising one laser diode (16) for each output, and each laser diode (16) being optically connected to one of these outputs.
10. Application according to claim 9, in which each laser diode (16) in each control unit (10) is installed in series with a separate control switch (28).
11. Application according to claim 10, in which a common safety switch (24) is installed in series with all laser diodes (16) in each control unit (10).
12. Application according to claim 9, in which the laser diodes (16) in each control unit (10) form a matrix of n rows and m columns, the laser diodes in each row being installed in series with a first control switch (28a) and the outputs of the laser diodes in each column being connected to a second control switch (28b).

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