EP1035402A2

EP1035402A2 - Device and method for artificially causing an avalanche

Info

Publication number: EP1035402A2
Application number: EP00103199A
Authority: EP
Inventors: Roberto Vassale
Original assignee: Monterosa SpA
Current assignee: Monterosa SpA
Priority date: 1999-03-11
Filing date: 2000-02-17
Publication date: 2000-09-13
Anticipated expiration: 2020-02-17
Also published as: EP1035402B1; EP1035402A3; ES2231059T3; DE60014993D1; ITMI990493A1; IT1311085B1; DE60014993T2; ATE280384T1

Abstract

The device for artificially causing an avalanche, comprises an explosive mass (2) and an actuation system (3) thereof, which comprises an actuator (4) provided with first safety means (5) insensitive to all types of electric currents, and to environmental stresses, and at least second safety means (6) that can be actuated by said first safety means only when the device is placed on the fixed point of the mass of snow.

Description

The present invention relates to a device and a method for artificially causing an avalanche.
As known, avalanches - that prevalently form in wintertime and that hurtle down to the valley in areas where tourist or sports activities are carried out, or where there are human settlements - are a serious problem
In fact, said phenomenon frequently originates dangerous situations for people, since they can be suddenly swept away by huge snow masses. In addition, it often affects the practicability of ski tracks or installations since the latter can be remarkably blocked by the avalanche masses.
Avalanches are generally originated by large amounts of snow that usually settles in the valleys below the mountain crest-line, where slopes are more marked and that, due to thermal variations or other stress, suddenly break off and fall downstream at increasing speed.
Snow masses, which can potentially cause avalanches, for reasons depending on the meteorological situations of the environment, can be essentially made up of masses of powdery snow possibly covered with a superficial icy layer originated by low temperatures.
Normally, after a heavy snowfall, or whenever the environmental situation leads to believe that dangerous avalanches may occur, a visual inspection is carried out to locate the sites where said phenomenon may occur.
Then, through the blasting of explosive charges placed on the surface of the snow mass, avalanches are caused in the sites thus determined.
Currently, for this purpose, the explosive charges used are made up of nitro-glycerine explosives, primed with a traditional method with detonator and fuse, placed on the surface of the snow mass by one or two operators who, after having reached the site for laying the charge on foot or by helicopter, and having lighted the fuses, remain on site, in most cases insecurely sheltered from the explosion, until the avalanche thus caused completes its course.
Said method presents several disadvantages among which the fact that the nitro-glycerine explosives used are especially shock-sensitive, above all at low temperatures; additionally, when handled, they cause illness such as strong migraines and vomiting.
Moreover, the operators are compelled to stay in the proximity of the charge explosion area; thus, they can be involved in the explosion or in the caused avalanche itself.
Last but not least it must be noted that, since in some countries explosives and detonators are not allowed for transport on helicopter, these interventions are carried out by the operators on foot, thus greatly increasing the operating time.
Another method for artificially causing an avalanche consists in using an explosive charge with an electronic timer, which can be launched from a helicopter thanks to a small parachute with which it is provided.
Nevertheless, the weight of the explosive mass of said device has a fixed value, and the explosive with which it is made, must be made up by the operator, right before use, by mixing two special substances, and inserting afterwards said explosive into a special container.
This method also presents significant disadvantages among which the fact that electric/electronic devices, although suitably controlled, are subject to accidental explosions as a consequence of stresses due to extraneous currents, such as electromagnetic inductions, electrostatic currents, stray environmental currents or currents produced during storms.
In addition, the explosive charge in question is provided with a single detonator and thus, in case of malfunction of the same, there are no other possibilities of making it blast at the desired moment.
Additionally, always with reference to the explosive charge in question, should it fail to blast, moving close to it because potentially it can still contain electric energy adapted to cause it to explode.
Another system consists in using an apparatus transported by helicopter, adapted to launch explosive charges on the snow.
This apparatus is extremely expensive, very bulky and unsafe.
In addition, in some cases fixed systems are used, called "gas-exp", which are capable of causing avalanches as a consequence of the explosion of a particular gas.
Nevertheless, being said systems fixed, they do not feature flexibility of use.
In this situation, the object of the present invention is that of solving the above-mentioned disadvantages of the prior art.
Within the scope of this technical task, an important purpose of the present invention is that of devising a device and a method for artificially causing an avalanche, which could be extremely safe in that they are not subject to environmental stresses and are provided with an actuation system having two different safeties, an ignition-based one and a mechanical one, operating in cascade.
Another purpose of the present invention is that of manufacturing a device and a method for artificially causing an avalanche, using a type of explosive especially insensitive to any type of stress and which, in addition, should be provided with a double system for priming the explosive charge instead of a single one so as to guarantee a complete operation safety.
A further purpose of the present invention is that of providing for a device and a method for artificially causing an avalanche, which allow the recovery of the explosive charge, in the very remote case of explosion failure, in total safety conditions since the charge is not capable of accidentally blasting because of external pressures such as, for example, extraneous currents or shocks.
Another purpose of the present invention is that of providing for a device and a method for artificially causing an avalanche, which would be extremely easy to use and have great flexibility of use since the explosive mass can be of different weight according to the situation.
A further purpose of the present invention is that of providing for a device and a method for artificially causing an avalanche, which allow to transporting the explosive charge by helicopter and releasing it in extremely fast and safe way, allowing to placing the explosive charge in the selected point, thus optimising the effects of the explosion and preventing the explosive charge from moving from where it has been placed, even in case of very leaning slopes and icy snow.
Another purpose of the present invention is that of providing for a device and a method for artificially causing an avalanche, which is completely safe and prevents possible undesired explosions also in the remote case of accidental shocks or falls from the helicopter used to transport the explosive charge.
Last but not least, a further purpose of the present invention is that of providing for a device and a method for artificially causing an avalanche, to be used in a range of temperatures comprised between -40 and +70 °C, having an extremely simple structure together with a valid functionality and having a reasonable price, so as to be widely used at low prices.
These objects, as well as the other purposes, are substantially achieved by a device for artificially causing an avalanche, comprising an explosive mass and a system for activating the same, characterised in that said actuation system comprises an actuator provided with first safety means insensitive to all types of electric currents, and to environmental stresses, and at least second safety means that can be actuated by said first safety means only when said device is placed on the fixed mass of snow.
Object of the present invention patent is also a method for artificially causing an avalanche, characterised in that it consists in determining the point for laying down an explosive charge made up of an explosive mass and in a system for activating the same; of arming said actuation system by inserting at least one detonator into at least one special seat; of bringing an explosive charge into a non-alignment position - in contrast to the action of a mechanical timer - with respect to said detonator; of holding said explosive charge into said position by means of a locking member; of associating said actuation system to said explosive mass; of igniting at least one fuse having a fixed combustion time and connected to said detonator; of arranging said explosive charge in said fixed point; and of removing said locking member so that said explosive charge aligns, after a fixed time, with at least said detonator and with said explosive mass.

Brief description of the drawings

Further features and advantages of the present invention will appear more clearly from the following detailed description of a preferred but not exclusive embodiment of a device and a method for artificially causing an avalanche, made by way of a not limitative example with reference to the attached drawings.
In such drawings:

Figure 1 shows a perspective exploded view of the actuation system according to the invention;
Figure 2 shows a perspective exploded view of the device according to the invention, wherein it is possible to see the container containing the explosive mass and the actuation system of the same according to the invention;
Figure 3 schematically shows the assembled device with the anti-rolling devices according to the invention;
Figures 4, 5 and 6 schematically show how the device is arranged on the mantle of snow to artificially cause an avalanche according to the invention;
Figure 7 shows a plan view of the armoured container for detonators according to the invention;
Figure 8 shows a sectioned side elevation view of the armoured container shown in Figure 7 according to the invention;
Figure 9 shows a detail of the armoured container according to the invention;
Figure 10 shows a different type of embodiment of the device according to the invention; and
Figure 11 shows a different type of embodiment of the container according to the invention.

With reference to the above figures, the device for artificially causing an avalanche according to the invention, referred to as a whole with the reference numeral 1, comprises an explosive mass, as a whole referred to with numeral 2, and an actuation system of the same, referred to as 3, as shown in figure 2.
Advantageously, the actuation system 3 comprises an actuator 4, provided with first safety means 5, insensitive to all types of electric current, and to environmental stresses, and at least second safety means 6, which can be actuated by the first safety means only when the device is arranged in the selected point of the mantle of snow so as to cause an avalanche in optimum conditions.
Actuator 4 is provided with a hollow body having a cylindrical shape 7, suitably made of a biodegradable material, which can be closed on the upper side with an upper plate 8 and on the lower side with a lower plate 9 through a "bayonet" joint 19.
In particular, the body 7 of the actuator is made of an extremely stiff and resistant material having a coefficient of thermal expansion which is practically equal to zero, and the ignition temperature is equal to about 430 °C.
Body 7 does not shrink at low temperatures, and thus it allows adjusting the operation of the mobile mechanisms with minimal dimensional tolerance.
In addition, the low ignition temperature causes an immediate combustion of the material on the explosion, and the formation of micro-fragments originated by the collapse of the structure, thus preventing environmental pollution.
In particular, the operation of the first safety means 5 is ignition-based, free from any type of stress, including those due to electric currents.
The first safety means 5 is defined by an igniter, and in particular by two frictioned igniters 9 that are connected to at least one fuse, and in particular, to two respective fuses 10, connected in turn to at least one detonator, and more precisely, to two detonators 11.
Suitably, each of the two portions of safety fuse 10 has a length of 100 centimetres and a combustion rate equal to 0.4 centimetres/second.
In this way, each of them burns within 4 minutes and 10 seconds.
Respective end portions of fuses 10 are connected to the frictioned igniters 9 inserted into respective holes 12 located on the upper plate 8.
After exiting the body 7 of the actuator, fuses 10 are externally wound around it, and are housed at their opposed ends into horizontal cylindrical seats 13, where they are fixedly held inside the same seats as detonators 11.
Also detonators 11 are provided in pairs to guarantee an ignition safety in at least one of them, and seats 13 are in reciprocal communication with one another so as to allow the blasting of both detonators also in the case one of them is not actuated by the relating fuse 10.
Once detonators 11 have been inserted into seats 13, the latter are closed through two rubber plugs 14.
The second safety means comprises a throttle element 15 having an elongated shape, which is provided with at least one explosive charge, or "booster", referred to with 16, in one end portion.
On its face, the lower plate 9 is provided with an aperture 20, which is occluded by the throttle element 15.
In particular, the throttle element 15 is mobile from a first position wherein the explosive charge 16 is not aligned with the two detonators 11, and at least a second position wherein the explosive charge 16 is aligned with detonators 11.
More precisely, the throttle element is mobile from the second position to the first position and vice versa in contrast to and for the action of a mechanical timer 21.
Timer 21 is provided with a quadrangular shaft 22 which engages in the relating seat 23 of the throttle element 15, which can rotate around pivot 24 located on the lower plate 9.
The throttle element is held into the first position of non-alignment of the explosive charge 16 with detonators 11 thanks to the engagement of a split pin 25, which passes through hole 26 of the upper plate 8 and of the housing seat 27 of timer 21 to engage with a hole 28 located on the throttle element.
When the split pin 25 is extracted from hole 28, timer 21 aligns the throttle element and thus, the explosive charge 16 with detonators 11, and consequently, with the explosive mass inserted by fusion into a cylindrical container 31 inside which, into seat 32, actuator 4 is housed.
In particular, the explosive mass 30, which can be made up of trinitrotoluene or tritolite, is actuated by detonators 11 through the explosive charge 16 present on the throttle element 15 when the latter is in the second alignment position, through aperture 20, also with the explosive mass 30.
Advantageously, the device also comprises some means to release container 31 from a helicopter, as a whole referred to with numeral 40, see figures 4 and 5, in the selected point of the mantle of snow, and adapted to cause the avalanche.
Additionally, the release means 40 is adapted - as it will be better detailed hereafter - to actuate the mechanical timer 21, thus bringing the throttle element 15 into an armament position.
In particular, the release means 40 comprises a "throwaway" cable 41, also made with a biodegradable material, and wound around a special roller arranged on the helicopter, which is provided at one end with the split pin or gudgeon 25 adapted to lock the throttle element 15 into the second position of non-alignment with detonators 11 and with the explosive mass 30.
In the proximity of the split pin or gudgeon 25, the cable is provided with a slot 42 adapted to engage with a hook 43 hinged on the edge of container 31 and mobile in contrast to and for the action of a pre-calibrated spring 44.
In this way, once the device has been laid on the mantle of snow, slot 42 disengages from hook 43, which returns to its initial position thanks to spring 44.
At this point, as it can be seen in figure 6, the split pin or gudgeon 25 is disconnected from the device through a traction of the cable operated from the helicopter and, as already pointed out, this operation will allow the rotation of the throttle element and thus, the alignment of the explosive charge 16 with the explosive mass 30 and detonators 11.
Finally, the cable is cut onboard of the helicopter and is released on the snow.
In addition, the device comprises anti-rolling means for the container; in particular, two bars 45 that are inserted into respective through holes 46 present on the same so as to create a hindrance to the rolling of container 31 along the mass of snow.
In addition, detonators 11 are advantageously contained into safety containment means of the same that is provided with a container 50 capable of preventing in the case of undesired explosion of detonators 11 consequences outside the container.
Advantageously, container 50 is adapted to cause the dissipation of the energy freed by the explosion of the detonators through the deformation of the structures wherein detonators 11 are inserted.
In particular, the detonators are arranged in groups of three inserted in a glass of soft steel 52 in which lead 53 has been introduced by fusion.
In turn, glasses 52 are arranged into special pits 54 obtained in a soft-wood parallelepiped 55.
Parallelepiped 55, between glasses 52, is provided with some chambers 56 having the purpose of disintegrating the residual shock wave of the possible explosion of the detonators, which occurs into the glasses themselves.
Advantageously, the outer surfaces of the container are internally covered with a neoprene layer 57 for the purpose of protecting it from vibrations.
Additionally, a wooden cover 58 is provided in the upper side; in its lower side, said cover is provided with lowered areas 59 in correspondence with the upper side of glasses 52.
In these lowered areas 59 there is a cork disk 60 which is laid on the three detonators 11 so as to hold them fixed, thus preventing any type of movement.
Also the cover is externally coated with neoprene.
Afterwards, the entire container is inserted into a primary container, not shown, made up of steel sheets welded to one another, and also provided with a cover that is fixed to the body thereof through suitable means.
The method for artificially causing an avalanche consists in the following operating sequence.
Before embarking the container of the explosive mass and of the actuation system of the same on a helicopter, the throttle element is made rotate from the second position to the first position, non-aligned with respect to the seats of detonators 11.
Then, the operation of the mechanical timer is tested to check whether it is adapted to bring the explosive charge, located inside the throttle element, into an alignment position with respect to said seats.
Afterwards, the explosive charge 16 is manually brought back, through aperture 20, in a non-aligned position, and is held in said position through the insertion of split pin 25 inside hole 28 thereof.
Now, it is possible to load on the helicopter, in three separate parts, the container 31 with the explosive mass 30, the actuation system 3 without detonators 1, and the container 50 containing the detonators.
Once the exact point for laying the device has been determined, bars 45 are inserted into the through holes 46 of the container; the actuation system is removed from the relating container; two detonators are taken from the armoured container 50, and are inserted into the respective seats 13, which are then occluded with plugs 14.
Afterwards, the actuation system is inserted into container 31 through, for example, a bayonet joint 60 located on the lower plate 9.
At this point, the explosive charge is ready to be released and, should the detonators explode, though it is an extremely remote event, the explosive mass would not explode since the explosive charge 16, or "booster", is not aligned with the detonators and with the explosive mass.
Slot 42 is applied onto hook 43, and the end of cable 41 is fastened through a simple knot, to split pin 25.
Finally, the frictioned igniters 9 are actuated, and the booster is released by unwinding the cable until it lays on the snow.
The explosive charge is freed from the hook as soon as it touches the snow; then, a traction is effected on the cable so as to extract the split pin from its seat, thus leaving the throttle element freely rotate so as to align the explosive charge, or "booster", with the detonators; the cable is cut onboard of the helicopter, and it is released.
At this point, after about 60 seconds after the extraction of the split pin, the explosive charge will be in the second position of alignment with the detonators by virtue of the rotation operated by the mechanical timer.
After about 4 minutes and 10 seconds from the ignition of the fuses, the detonators will explode, thus causing the cascaded blasting of the explosive charge, or "booster", and of the underlying explosive mass.
The invention achieves the proposed purposes, obtaining several important advantages.
In fact, a device and a method for artificially causing an avalanche have been invented which carry out the priming steps in a totally mechanical-igniferous way, so as to prevent the explosive charge from running the risk of untimely explosions caused by all types of extraneous currents that can generate in high-mountain environments and in a helicopter.
The laying method through the use of a (throwaway) cable and of a release hook at the end of the traction allows positioning the explosive charge exactly in the point selected, thus optimising the effect of the explosion.
In addition, thanks to the presence of two ignitions that operate concurrently, there is a complete operation safety.
Always as regards to safety, should the device according to the invention not explode once positioned on the snow, it would not have any other chance of blasting since it is not provided with mechanisms that may cause it to explode.
Additionally, the explosive charge is available with different weights of the explosive mass.
The invention thus conceived can be subject to several modifications and variants, all falling within the scope of the concept of the present invention.
For example, an alternative of embodiment, shown in figure 10, actuator 4 is provided with an additional safety made up of a split pin 80 adapted to hold the throttle element 15 into position, locked into the first position.
Additionally, container 31 can be provided with horizontal ribs 81 for the purpose of having a greater surface resistance and for holding the explosive it contains, inserted by fusion, with greater efficacy.
In a different embodiment, a metal mass 83, weighing about 1 kg, is provided at the end of cable 41, and a half ring 84 is provided in the lower side of said metal mass.
Spaced from the metal mass, the cable is also provided with three safety hooks 85, the first two of which are connected to igniters 9 so as to actuate them when the explosive charge is laid on the snow through cable 41, instead of activating it onboard of the helicopter.
The third hook is connected to split pin 80, which is disconnected from its seat during the cable recovery and the actuation of the igniters.
Container 50 can also be manufactured so as to be provided, in place of the steel glasses 52, with a wooden parallelepiped 86, wherein the detonators are housed, immersed into a honeycomb structure 91, as shown in figure 11.
In the container, in barycentric position, there is provided a parallelepiped 86, made of soft wood (fir), horizontally divided into two parts 89 and 90.
The latter are held in place by as many "honeycomb" structures 91 and 92, which are in turn fastened to the bottom of the box and to the cover through a special adhesive.
In the lower side of the above parallelepiped, it is possible to see 12 holes 93, adapted to house as many detonators for 2/3 of their height; the remaining third part needed to extract them is enclosed into small cells 94, located in a structure that can be extracted from the assembly and arranged in the lower part of the other side of the parallelepiped, in the case of transport of fuse-detonators.
With reference to the transport of electrical detonators, the above-mentioned extractable structure is removed, and in the opening thus obtained, the rheophores of the electrical detonators are arranged.
The box is laterally provided with two handles 95 and two coupling systems for fastening it to the loading platform of the helicopter.
The capability of the container of absorbing and dissipating the energy freed from the detonator blasting is due both to its strong outer structure, and to the particular "honeycomb" configuration of its inner structure.
In fact, since the latter breaks as the shock wave and the gases generated by the detonator blasting pass through it, it deducts a considerable amount of energy from the two particular phenomena, thus causing a rapid decay of their typical parameters.
Finally, it must be pointed out that the metal structure of the containers acts as a FARADAY cage, and that its inner part is totally made of wood.
Thus the detonators, with particular reference to electrical detonators it houses, cannot be in any way subject to stresses due to electric, induction, contact or electrostatic currents.
Additionally, all parts can be replaced with technically equivalent elements.
The materials, shapes and dimensions used can be of any type according to the needs.

Claims

Device for artificially causing an avalanche, comprising an explosive mass and an actuation system of the same, characterised in that said actuation system comprises an actuator provided with first safety means insensitive to all types of electric currents, and to environmental stresses, and at least second safety means that can be actuated by said first safety means only when said device is placed on the fixed point of the mass of snow.
Device according to claim 1, characterised in that said actuator is provided with a substantially hollow body made of a biodegradable material, closed by an upper plate and by a lower plate.
Device according to claim 1 or 2, characterised in that the operation of said first safety means is ignition-based.
Device according to any one of the previous claims, characterised in that said first safety means comprises at least one frictioned igniter connected to at least one fuse, connected in turn to at least one detonator.
Device according to one or more of the previous claims, characterised in that said second safety means comprises a throttle element having an elongated shape, which is provided with at least one explosive charge in one end portion.
Device according to one or more of the previous claims, characterised in that said lower plate is provided with an aperture occluded by said throttle element.
Device according to one or more of the previous claims, characterised in that said throttle element is mobile from a first position wherein said explosive charge is not aligned with said detonator, and at least a second position wherein said explosive charge is aligned with said detonator.
Device according to one or more of the previous claims, characterised in that said throttle element is mobile from said second position to said first position and vice versa in contrast to and for the action of, a mechanical timer.
Device according to one or more of the previous claims, characterised in that said actuator is housed into a container wherein said explosive mass made up of a blasting explosive is inserted by fusion.
Device according to one or more of the previous claims, characterised in that said explosive mass is actuated by said detonator through said explosive charge present onto said throttle element.
Device according to one or more of the previous claims, characterised in that it comprises means for releasing said container in said selected point, said release means being adapted to actuate said mechanical timer.
Device according to one or more of the previous claims, characterised in that said release means comprises a "throwaway" cable provided at one end with a split pin for locking said throttle element and, in the proximity of said split pin, a slot adapted to engage with a hook associated to said container and mobile in contrast to, and for the action of, a spring.
Device according to one or more of the previous claims, characterised in that it comprises anti-rolling means for the container onto said mantle of snow.
Device according to one or more of the previous claims, characterised in that said anti-rolling means comprises at least two bars inserted into respective through holes present on said container.
Device according to one or more of the previous claims, characterised in that it comprises safety enclosure means of said at least one detonator, provided with a container adapted to prevent external effects in the case of explosion of said detonator.
Device according to one or more of the previous claims, characterised in that said container comprises at least one glass of soft steel containing fused lead, inside which said at least one detonator is housed.
Device according to one or more of the previous claims, characterised in that said glass is arranged in at least one special pit obtained in a soft-wood parallelepiped.
Device according to one or more of the previous claims, characterised in that said soft-wood parallelepiped is provided with some chambers arranged around said glass and adapted to make the residual shock wave of the explosions occurring inside said glasses decay.
Device according to one or more of the previous claims, characterised in that said outer surfaces of said container are internally covered with neoprene for the purpose of protecting it from vibrations, and that its cover is provided with a lowered area arranged on the upper part of said glass, housing at least one cork disk adapted to hold at least said detonator into said glass.
Device according to one or more of the previous claims, characterised in that said actuator is provided with an additional safety made up of a split pin adapted to hold said throttle element into said first position.
Device according to one or more of the previous claims, characterised in that said container is provided with horizontal ribs for the purpose of having a greater surface resistance and for holding the explosive it contains, inserted by fusion, with greater efficacy.
Device according to one or more of the previous claims, characterised in that one end of said release cable is provided with a metal mass, provided in turn with a half ring at its lower side; and, at a certain distance therefrom, with three safety hooks of which the first two are connected to said igniters so as to activate them when the explosive charge is laid on the snow, instead of activating it onboard of the helicopter; and in that the third hook is connected to said additional split pin which is disconnected from its seat during the recovery of said cable and the actuation of said igniters.
Device according to one or more of the previous claims, characterised in that said container is provided with a wooden parallelepiped, wherein said detonators are housed, immersed into a "honeycomb" structure.
Method for artificially causing an avalanche, characterised in that it consists in determining the point for laying down an explosive charge made up of an explosive mass and of a system for activating the same; of arming said actuation system by inserting at least one detonator into at least one special seat; of bringing an explosive charge into a non-alignment position with respect to said detonator - in contrast to the action of a mechanical timer - of holding said explosive charge into said position through a locking member; of associating said actuation system to said explosive mass; of igniting at least one fuse having a fixed combustion time and connected to said detonator; of arranging said explosive charge into said fixed point; and of removing said locking member so that said explosive charge aligns, after a fixed time, with at least said detonator and with said explosive mass.
Method according to claim 20, characterised in that the combustion time of said fuse is greater than the time for laying said explosive mass and said actuation system, added to the alignment time of said explosive charge with said detonator.
Method according to one or more of the previous claims, characterised in that the alignment time of said explosive charge with said detonator and said explosive mass is enough for the operators to move away after having laid it down.