GB2454540A - Blast and shrapnel mitigation apparatus - Google Patents

Abstract

An apparatus for blast mitigation comprising a layer 40 of blast mitigating substance contained by a frangible mantle 3 and a layer of anti-ballistic substance 13, 15, 17 adjacent the mantle. The frangible mantle 3 encloses a cylindrical compartment 1; a plurality of which are arranged into interconnected layers 40 having tubes 4 which allow fluid flow there between. The tubes are filled with blast mitigating substance such as water, gel, viscous liquid or sand. Antiballistic layers 13, 15, 17 are arranged with increasing antiballistic resistance comprising polyamide, aramid and HPPE materials respectively. The apparatus may comprise modular units which can be coupled to adjacent units to form a safety screen.

Description

BLAST MITIGATION

FIELD OF THE INVENTION

The present invention relates generally to the field of blast mitigation that results in a decrease of the damage associated with explosives.

BACKGROUND OF THE INVENTION

Terrorist attacks which target civilians and public places by using charges and bombs, as well as ordnance and explosives in storage, etc., are common in today's world. When such a bomb or charge explodes, it can damage nearby buildings and structures and may result in injuries and even fatalities. The damage, which originates from the blast, is caused by two main phenomena: the air shock waves and the shrapnel, which propagate following the blast. The air shock waves are short duration compressive waves, which move radially outward through the air from the blast source. These high pressure waves, which propagate immediately, create a shock wave which causes devastation through their propagation. The shock waves also heat the air to extremely high temperatures, a phenomenon known as the fireball effect. The shrapnel, which is spread following the blast, gains its high kinetic energy from the blast's energy and, therefore, is another source of damage and devastation.

Blast mitigation has been addressed in the past by a number of methods and systems. In times past, sandbags were piled up to absorb some of the blast energy. In most recent cases, liquid, and especially water, was used for the blast mitigating device. The water is used to suppress a large proportion of the energy of the bomb blast. An example of this can be seen in Barrett, U.S Patent No. 4,836,079, which describes a frangible container filled with liquid positioned so as to cover a bomb.

When the blast occurs, the container is broken by the detonation and the released liquid limits the shock wave propagation and the fireball effect.

Another approach involves a sensor-activated water suppression system. This type of system has been designed to suppress the blast and the incendiary effects ( from the blast by means of the rapid combustion of liquid. Examples of such a system can be found in Burky et al, U.S Patent No. 6,119,574.

Liquid foams were also suggested as means for blast mitigation. An example of this approach is disclosed in Moxon et al, U.S Pat. No. 4,964,329.

In all these systems, a liquid substance is the main material utilized for blast mitigation. However, liquids are effective mainly for the suppression of the shock wave originating from the blast and for the decrease of the high temperature. The effect of the water is limited with regard to shrapnel which originates from the charge and follows the shock wave. Thus, when the shrapnel interacts with the mitigating material, such as water, which is present in the prior art systems, this mitigating material has already interacted with the shock waves and, therefore, the effectiveness of the liquid with regard to stopping the energetic shrapnel is significantly reduced.

The inability of existing devices to effectively mitigate both the shock wave energy and the shrapnel energy is becoming more and more of a liability, as terrorists' charges deliberately contain metal nails and other sharp metal debris.

Accordingly, it is the purpose of this invention to provide an apparatus and method, which will mitigate more effectively, first the shock wave and the temperature increase caused by a blast and, in addition, will entrap the high-energy shrapnel which is scattered following the air shock wave, while providing a flexible method of placing the apparatus at the required location.

SUMMARY OF THE iNVENTION

There is provided according to the present invention an apparatus and a method for mitigation of the effects associated with both blast and shrapnel. The mitigating apparatus is designed with alternating layers of blast mitigating substance, preferably liquid or gel or other viscous fluid, and anti-ballistic substance, preferably a textile, to treat the two main causes of damage originating from a detonation or explosion, namely, the air shock wave, which is the first to propagate after the explosion, and the bomb-generated fragmentation and shrapnel, which propagate following the air shock wave. The fluid suppresses the air shock wave, absorbing some of its energy, and the anti-ballistic textile layers inhibit continued movement of the shrapnel.

Preferably, the anti-ballistic textile layers covering the apparatus' blast mitigating compartments are designed with varying anti-ballistic performance and arranged such that they allow the portion of the shock wave's energy not absorbed by the apparatus to be released in a defined direction.

The blast mitigation substance of the apparatus is held in at least one closed compartment, which surrounds the explosive charge. The lower or inner wall of the compartment is placed on top of or around the explosive and is made of a material which is ruptured by the air shock wave created in the explosion. The upper andlor external walls of the compartment are covered with or made of anti-ballistic textile.

In this way, the apparatus absorbs the shock wave's energy without being completely dismantled, and is still able to suppress the shrapnel's kinetic energy and decrease the damage it can cause.

According to one embodiment of the invention, the apparatus is made of several layers of blast mitigation compartments, where an anti-ballistic textile layer covers each blast mitigation compartment layer. The anti-ballistic layers are preferably arranged such that the outer layers have better anti-ballistic impact performance than the inner layers.

Preferably, a special section of the most external layer, or certain sections of other layers, are specially designed to allow the remainder of the shock wave's energy not absorbed by the liquid, to be released in a defined direction. In one embodiment of the invention, this design includes at least one layer of an anti-ballistic textile sheet attached to the outer cover of the apparatus only on one side thereof. This facilitates release of the remainder of the high pressure shock wave along the other side of the sheet, in a pre-selected upward direction.

In another embodiment of the invention, the layers of the anti-ballistic substance are arranged such that they have higher anti-ballistic performance in certain sections than in other sections, both in the inner layers and in the outer layers.

This design routes the air shock wave through the sections having lower anti-ballistic performance to release them to the environment. One example includes providing a "window" in the anti-ballistic layer directly above each liquid compartment layer.

The apparatus may be provided with the blast mitigating substance already inside its compartments, or it may be provided empty and be filled on site with the blast mitigating substance. When the blast mitigating substance is a gel, powdered gel may be provided inside the compartments, and the compartments can be filled with water on site. The fact that the apparatus may be filled with the blast mitigating substance on site enables it to provide protection also against large size explosive charges. In such cases, the empty apparatus is considerably lighter (and smaller) than the filled apparatus, and can be carried by a single person. The apparatus is positioned on top of or around the explosive charge, and following that, can be filled with water or other fluid using a filling connection.

There is thus provided, according to the present invention, an apparatus for blast mitigation of an explosive charge, the apparatus including at least one layer of blast mitigating substance contained by a frangible mantle; at least one layer of anti-ballistic substance disposed adjacent the mantle; the layers of blast mitigation substance and of anti-ballistic substance being adapted and constructed for placement in proximity to the explosive charge so as to absorb both blast and shrapnel from the charge. Preferably, the apparatus includes at least two layers of blast mitigating substance in a frangible mantle, alternating with at least two layers of an anti-ballistic substance.

According to one embodiment of the invention, the layers of blast mitigating substance and anti-ballistic substance are concentric annular layers.

According to an alternative embodiment of the invention, the layer of blast mitigating substance includes at least one modular unit adapted and configured for coupling to another modular unit, the anti-ballistic substance being disposed adjacent at least part of the modular unit.

There is also provided, according to the invention, a method of forming an apparatus for blast mitigation of an explosive charge, the method including providing at least one layer of blast mitigating substance contained by a frangible mantle; and disposing at least one layer of anti-ballistic substance adjacent the mantle; the layers of blast mitigation substance and of anti-ballistic substance being adapted and constructed for placement in proximity to a explosive charge so as to absorb both blast and shrapnel from the charge.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be further understood and appreciated from the following detailed description taken in conjunction with the drawings in which: Figure 1 depicts a cross section of one embodiment of the proposed apparatus for suppressing the blast of a charge.

Figure 2 is a schematic illustration of an arrangement of anti-ballistic layers in an apparatus according to one embodiment of the invention.

Figure 3 is an exploded view of the apparatus of Figure 1.

Figure 4a is a top sectional view of an apparatus according to an alternative embodiment of the invention, for suppressing blast of a charge.

Figures 4b and Ic are cut-away perspective and side sectional views, respectively of the apparatus of Figure 4a.

Figure 4c is a top sectional view of an apparatus according to another alternative embodiment of the invention.

Figures 5a, Sb and 5c are top, perspective and side sectional illustrations of a blast mitigating modular unit constructed and operative according to an alternative embodiment of the invention.

Figure Sd is a schematic illustration of a number of modular units fitted together to form a blast mitigating wall.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a system and method for mitigating the damage incurred by the blast of a charge. More particularly, the invention deals with an apparatus and a method for mitigation of the effects associated with blasts adjacent the apparatus, both shock wave and shrapnel. This is accomplished by providing an apparatus containing alternating layers of anti-ballistic sheets and at least one compartment which contains a blast mitigating substance, preferably a liquid or gel or other viscous fluid, which is arranged to be disposed on or around the charge. This particular architecture enables mitigation of damage caused both by the shock wave and shrapnel associated with exploding charges. It will be appreciated that the apparatus chiefly provides protection against lateral propagation of the shock wave and shrapnel, permitting channeling of excess energy of the blast upwards, above the exploding charge.

In Figs. 1 and 3, there are shown cross sectional and exploded illustrations, respectively, of' a blast mitigating apparatus constructed and operative in accordance with one embodiment of the invention. In this embodiment, the apparatus 10 includes a bottom cover 6, an upper cover 2, a side cover 2', and a plurality of substantially cylindrical compartments 1. Each cylindrical compartment 1 includes a frangible, water resistant mantle 3 filled with an appropriate blast mitigating substance (preferably water, gel or viscous fluid suited for absorbing kinetic energy, although alternatively, sand or powdered material or any other blast mitigating material can be utilized). Mantle 3 is preferably made of a thin layer of a material, such as polyethylene, arranged to contain the blast mitigating substance. The mantle is ruptured when the explosion occurs, causing the blast mitigation substance to absorb a portion of the generated shock wave and consequent high temperature wave.

Cylindrical compartments 1 are arranged in a plurality of layers 40, 40', and 40". The cylindrical compartments in each layer are interconnected via tubes 4, 4' and 4", permitting fluid flow therebetween. The cylindrical compartments are filled ( with blast mitigating substance, as via tubes 12. Interconnecting tubes 4, 4' and 4" permit the rapid filling of the entire apparatus.

The apparatus further includes a plurality of anti-ballistic material layers 13, 15, and 17 disposed between layers 40, 40' and 40", and preferably extending from one side to another of side cover 2'. Apparatus 10 may also include additional anti-ballistic material layers 22, 24, 26 and 28, which are connected only to one side of side cover 2'.

The apparatus 10 is designed so that, upon blast, the alternating layers will mitigate both the shock wave and the shrapnel. It will be appreciated that the shrapnel generated by a blast often has such high kinetic energy that it can cut right though a sheet of anti- ballistic fabric. The blast mitigating substance and internal anti-ballistic layers of the apparatus of the invention absorb some of this kinetic energy, so that high energy fragments can be trapped in one of the outer layers of anti-ballistic material.

Preferably, anti-ballistic layers 13, 15 and 17 are designed with an increasing level of anti-ballistic properties. Thus, the upper anti-ballistic substance layer 17 will have better anti-ballistic impact performance than the next lower anti-ballistic substance layer 15, which, itself, has better anti-ballistic performance than anti-ballistic layer 13. This can be implemented by using, for example, a Polyamide-type material as the anti-ballistic substance layer 13, using an Aramid-type material, which is known to provide better anti-ballistic mitigation over Polyamides, in layer 15, and then integrating an even stronger anti-ballistic substance in layer 17, such as High Performance Polyethylene (HPPE). This design maximizes the interception of flying shrapnel and still allows the shock wave to propagate through the apparatus while mitigating its energy. Side cover 2' is made of a high impact performance anti-ballistic substance and is preferably an arcuate, woven anti-ballistic sheet, impeding laterally flying shrapnel, and is coupled to the bottom wall 6 and top cover 2. lop cover 2 preferably is made of a high impact anti-ballistic material, such as HPPE.

Beyond the upper level 40" of blast mitigating cells, there are additional layers ( 28, 26, 24 and 22 of substance, preferably anti-ballistic material, which serve to stop flying shrapnel while still enabling the remainder of the shock wave to be released in a defmed direction, i.e., upwards over the charge. A schematic illustration of an arrangement of anti-ballistic layers 22, 24, 26 and 28 in apparatus 10, according to one embodiment of the invention, is shown in Figure 2. These layers are connected to the side cover 2' of the apparatus only along a single edge, so that the remaining shock wave energy can be released along the opposite edge. Thus, layer 28 is illustrated as being coupleable via edge 27 to one side of side cover 2' (not shown).

Layer 26 is disposed for coupling to the opposite side of side cover 2', via edge 25.

Layer 24 is disposed to be coupled to another side of side cover 2', via edge 23, in 900 rotation relative to edge 27. Layer 22 can be coupled to side cover 2' via edge 21, opposite edge 23. This architecture of anti-ballistic layers allows the shock wave to propagate in the vertical direction, while forcing it to pass along the longest possible route through the blast mitigating apparatus, thus substantially reducing its energy.

In an alternative embodiment of the invention, at least one of layers 13, 15 and 17 includes at least one portion coupled to the rest of the layer along only one edge, creating an area with an effective lower anti-ballistic perfonnance and thus functioning as a window for releasing the remainder of the shock wave created in the blast. Preferably, this portion is located above at least one liquid compartment.

The apparatus of the embodiment of Figure us utilized by placing it on the explosive charge 50. When the charge explodes, the special design of the apparatus mitigates damage caused by the explosion in the following manner: First, the bottom wall 6 of the apparatus, made of a low anti-ballistic performance material, is dismantled by the first high pressure air shock wave. The mantle 3 of the bottom blast mitigating compartments layer 40 then is ruptured by the air shock wave and the following high temperature gases generated by the explosion, causing a release of the blast mitigating substance, which interacts with the high temperature and pressure gases. Then, the first anti-ballistic substance layer 13 interacts with the somewhat quenched shock wave, by absorbing some of its remaining energy, and trapping some of the shrapnel which are spread following the shock wave, whose kinetic energy has been reduced by the blast mitigating fluid. Layer 13 is preferably chosen such that it absorbs part of the energy while being dismantled, so that the high-pressure wave can propagate through it to the upper layers of the apparatus. The upper layers 40', 40" function in the same manner as the first liquid compartment layer 40, but they interact with a lower energy shock wave and with gases which were partially suppressed already by the bottom layers of the apparatus. Layers 15 and 17 preferably are also chosen such that they will absorb the explosion energy while being torn, leaving the pressure wave to continue propagating in the upwards direction by shifting layers 28, 26, 24 and 22 upwards, while their edges remain coupled to the apparatus' external side cover 2'. The shock wave energy is released from the upper external cover 2 of the apparatus, while the anti-ballistic layers 28, 26, 24 and 22, as well as the side external cover 2' absorb the laterally propagating shrapnel, while leaving its remaining energy to disperse mainly in the vertical direction. The side cover 2' of the apparatus, which is made of a strong anti-ballistic sheet, blocks the pressure wave from expanding laterally and, therefore, forces the remaining energy of the explosion to propagate mainly in the vertical direction.

Thus, the apparatus is able to alternately absorb and quench the blast energy, which becomes smaller while passing through each layer, and to direct the remaining energy for release in a preferred direction while blocking most of the blast energy in other directions and stopping the flying shrapnel. While a device having a plurality of alternating layers, as described above, is preferred for larger charges, it will be appreciated that the apparatus of the invention may, alternatively, have only one layer of blast mitigating material and one layer of anti-ballistic material.

With reference to Figures 4a, 4b and 4e, there is shown an apparatus 60, according to an alternative embodiment of the invention, for mitigating the blast of a charge 62. Apparatus 60 includes an internal, annular or elliptical layer 64 of anti-ballistic substance, preferably Kevlar�, surrounded by an external annular or elliptical layer 66 of blast mitigating substance (e.g., water, gel, highly viscous energy absorbing fluids, sand, powder, etc). In this embodiment, layer 66 consists of a single closed compartment having a frangible mantle 68 formed, for example, of polyethylene. A second layer 70 of anti-ballistic substance is preferably provided outside the blast mitigating substance layer 66, for entrapping fragments that were not entrapped by internal layer 64, whose kinetic energy has been somewhat dissipated by the fluids in blast mitigating substance layer 66. It will be appreciated that layers 64, 66 and 70 are preferably concentric. A top cover layer 72 of blast mitigating substance 71 held in a frangible mantle is provided covering layers 64, 66 and 70. In addition, additional outer layers of blast mitigating substance 74 and anti-ballistic material 76 may be provided around layer 70, for providing protection against larger charges, as shown in Figure 4c. Top cover 72 is generally only a blast mitigating layer to facilitate release of the unabsorbed energy of the explosion in a preferred direction, i.e., in an upwards direction over the charge, although a layer of anti-ballistic material (not shown) may be provided on or under cover layer 72. It will be appreciated that the apparatus preferably is filled with the blast mitigating substance in situ, for ease of transportation and assembly.

Operation of the apparatus of this embodiment is as follows. The apparatus is disposed around charge 62, which is contained in the cavity formed inside internal layer 64. Apparatus 60 is designed to be placed over or around the charge, with inner layer 64 being closest to the charge. Internal layer 64 is made of an anti-ballistic material that breaks upon interaction with a propagating shock wave and shrapnel, absorbing some of their energy in the process and entrapping the lower energy fragments. According to a preferred embodiment of the invention, internal layer 64 is formed of at least one full circle of Keviar� sheet wrapped around itself. The mantle 68 of the blast mitigation substance in layer 66 breaks upon interaction with the propagating shock wave, releasing the blast mitigating substance and absorbing more of the shock wave's energy. Anti-ballistic layer 70 is designed to intercept flying shrapnel not trapped by internal layer 64. If additional mitigation is required, as in Figure 4c, the apparatus may include one or more additional alternating layers of blast mitigating substance surrounded by anti-ballistic fabric. In this case, the blast and shrapnel mitigation process, as described above, is repeated.

The apparatus of the present invention can be used as a screen, to protect people and objects (buildings, cars, etc.) from a charge which explodes in their vicinity. Thus, the apparatus can be erected in advance, for example, to form a protecting screen adjacent an entrance to a building, such as a hotel entrance, or erected as needed to cover a charge or to form, for example, an evacuation screen or safety comdor for safe passage in dangerous surroundings, check points, and so on.

With reference to Figures 5a, 5b and 5c, there is shown a schematic illustration of a modular blast mitigating unit 80, constructed and operative according to an alternative embodiment of the invention. Modular unit 80 includes a top wall 86, a bottom wall 88 and a side waIl 82, defming a compartment 90 for holding a blast mitigating substance. Modular unit 80 is shaped to enable fitting of a number of units closely together in an interlocking relationship. A sheet 83 of anti-ballistic material may be affixed to any or all of the outer walls of the modular units. Modular unit 80 further includes filling elements 84, that may be closed using an appropriate cap, for filling space 90 with a blast mitigating substance. Preferably, filling elements 84 protrude from top wall 86 for use also as coupling elements, for coupling to additional modular units 80' seated on top. Complementary recesses 89 are preferably provided in the bottom wall 88' of modular units 80, 80' for coupling the modular units like Lego� blocks.

An advantage of the irregular shape of the modular unit 80 of this embodiment is that it eliminates line-of-sight gaps between adjacent units. Such gaps, if they exist, could serve to permit the unwanted passage of blast radiation.

In Figure 5d, there is shown a schematic illustration of a blast mitigating wall formed by a number of modular units 80, fitted together. The fitted modular units 80 preferably are separated from one another by anti-ballistic sheets 83 (e.g., Keviar� sheets) that line the outside walls of the modular units. The outer walls of the constructed screen or apparatus may be lined with anti-ballistic sheets, so to further improve shrapnel interception.

It will be appreciated that a plurality of such safety screen elements can be combined with others, so as to form a V or U shaped apparatus for use in protecting against the effects of an explosive charge.

The modular units may be filled with the blast mitigating substance just before or after assembly, providing maximum mobility and ease of assembly. It will be appreciated that water or other easily disposable liquid, is the preferred blast mitigation substance for one-time use. However, gel is preferred in cases where the protective screen is expected to be in use as a protective screen for a relatively long time. This is due to the fact that, even if a small hole develops in the mantle, the semi-solid gel will not leak out, so the protective barrier will remain intact.

According to a preferred embodiment of the invention, the gel is a polyacrymalide.

More preferably, the gel is a non-toxic biodegradable polyaciymalide. Most preferably, the gel is a non-toxic polyacrymalide that biodegrades to C02, nitrogen and water. Alternatively, any other suitable gel can be utilized.

When water is the blast mitigating substance, it may be desirable to add bleach or other antimicrobial material to the water to prevent the growth of mold, mildew, algae, and microbes in the water when the water is left in the blast mitigating apparatus for extended periods of time. In addition, it will be appreciated that sometimes terrorists put biological substances in with their explosives, e.g., HCV or HIV infected blood. If desired, the blast mitigating substance (particularly when in liquid form) may include biological warfare-mitigating substances, which mist the entire area of the blast with the chosen anti-biological substance upon detonation.

Bleach also serves as such a biological warfare mitigating substance. Alternatively, or in addition, the internal compartments of the blast mitigating apparatus may be provided with substances which provide radiological weapon mitigating protection.

Such substances are those which reduce or eliminate alpha., beta and gamma rays prior to explosion of the charge.

According to another embodiment of the invention, the innermost layer of the device can be fitted with a light source, such as light-emitting film, and mirrors and/or remotely operated robotic tools (not shown). These devices would permit examination and/or dismantling of the explosive charge while it is inside the blast mitigating apparatus, without endangering an operator.

While the invention has been described with respect to a limited number of embodiments, it will be appreciated that many variations, modifications and other applications of the invention may be made. It will further be appreciated that the invention is not limited to what has been described hereinabove merely by way of example. Rather, the invention is limited solely by the claims which follow.

Claims (26)

1. An apparatus for blast mitigation of an explosive charge, the apparatus comprising: at least one layer of blast mitigating substance contained by a frangible mantle; at least one layer of anti-ballistic substance disposed adjacent said mantle; said layers of blast mitigation substance and of anti-ballistic substance being adapted and constructed for placement in proximity to the explosive charge so as to absorb both blast and shrapnel from said charge.

2. The apparatus according to claim 1, wherein said layers of blast mitigating substance and anti-ballistic substance are concentric annular layers.

3. The apparatus according to claim 1, wherein said layer of blast mitigating substance comprises at least one modular unit adapted and configured for coupling to another modular unit, said anti-ballistic substance being disposed adjacent at least part of said at least one modular unit.

4. The apparatus according to claim 3, further comprising a plurality of said modular units coupled to one another to form a safety screen element

5. The apparatus according to claim 1, wherein said layer of blast mitigating substance includes a plurality of interconnected compartments.

6. The apparatus according to any of the preceding claims, comprising at least two layers of blast mitigating substance in a frangible mantle, alternating with at least two layers of an anti-ballistic substance. (

7. The method of claim 6, wherein said at least two layers of anti-ballistic substance have different anti-ballistic characteristics.

8. The apparatus according to any of the preceding claims, further comprising a top layer of blast mitigating substance in a frangible mantle.

9. The apparatus according to claim 8, further comprising at least one top layer of anti-ballistic substance disposed on top of said top layer of blast mitigating substance.

10. The apparatus according to claim 9, wherein said at least one top layer includes a plurality of layers disposed on top of said top layer of blast mitigating substance.

11. The apparatus according to any of the preceding claims, wherein said blast mitigating substance is water.

12. The apparatus according to any of claims I to 10, wherein said blast mitigating substance is a gel.

13. The apparatus according to claim 12, wherein gel powder is disposed in said mantle for formation on site of said gel by the addition of water.

14. The apparatus according to any of the preceding claims, wherein said blast mitigating substance is a viscous liquid.

15. The apparatus according to any of the preceding claims, further comprising a least one filling element for each said layer of blast mitigation substance.

16. The apparatus according to any of the preceding claims, wherein said anti-ballistic substance is selected from the group consisting of Polyamide-type material, Aramid-type material, High Performance Polyethylene (HPPE) and Keviar�.

17. A method of forming an apparatus for blast mitigation of an explosive charge, the method comprising: providing at least one layer of blast mitigating substance contained by a frangible mantle; and disposing at least one layer of anti-ballistic substance adjacent said mantle; said layers of blast mitigation substance and of anti-ballistic substance being adapted and constructed for placement in proximity to a explosive charge so as to absorb both blast and shrapnel from said charge.

18. The method according to claim 17, further comprising the step of adding said blast mitigating substance after placement.

19. The method according to claim 18, further comprising providing gel in powder form in said mantle for filling with liquid on site to form a gel.

20. The method according to any of claims 18 to 19, further comprising arranging alternating layers of blast mitigating fluid in a frangible mantle, and anti-ballistic substance, for placement adjacent an explosive charge so as to absorb both blast and shrapnel from said charge.

21. The method according to claim 20, wherein said layers of the anti-ballistic substance have different anti-ballistic characteristics. (:4

22. The method according to any of claims 18-21, wherein said blast mitigating substance is water.

23. The method according to any of claims 18 to 21, wherein said blast mitigating substance is gel.

24. The method according to any of claims 18 to 21, wherein said blast mitigating substance is a viscous liquid.

25. The method according to any of the preceding claims, wherein said anti-ballistic substance is selected from the group consisting of Polyamide-type material, Aramid-type material, High Performance Polyethylene (HPPE) and Keviar�.

26. A method for mitigation of effects of a blast of a charge, the method comprising: alternately disposing, adjacent the charge, layers substantially for shock wave absorption and layers for mitigation of shrapnel dispersion.