BLAST DEFENCE BARRIER

Field of the Invention

The present invention relates to a barrier assembly for the protection of personnel and property against attack and more particularly to a modular barrier assembly formed of barrier elements adapted to attenuate or eliminate the effects of an adjacent explosion or forced vehicle entry. The invention further relates to a method of assembling barrier elements and a method of forming a barrier assembly or enclosure utilising the barrier elements.

Background to the Invention

It is well appreciated that in the current global security environment and in future predicted scenarios that there is a requirement for highly mobile expeditionary armed forces and for peace keeping forces to be deployed in highly volatile environments. As these forces tend to be small there is greater need for them to have fortified positions and a means of physically protecting personnel and equipment against armed factions, insurgencies and other irregular forces in addition to guerrilla attacks and other techniques associated with terrorist organisations, for example in what has become to be known as asymmetric warfare. Additionally, such expeditionary armed forces may be forced to engage regular forces to prevent incidences of ethnic cleansing and genocide. In each of these scenarios it is vital to reduce casualties of off-duty and security personnel and to decrease the risk of losing vital equipment that would be difficult or time- consuming to place in a time-critical situation.

The fortification of a position or base of operations is considered essential and

ease of deployment of a means of fortification is of particular concern to these highly mobile forces. Traditionally concrete blocks, either imported or made in situ, or sand bag barriers are used to protect such fortified positions and are often used to surround gun emplacements and ammunition dumps. In the case of concrete blocks, these need to be of a particularly large size to provide adequate protection and there is a significant risk of secondary shrapnel being produced when the barrier is hit by a projectile from any one of a number of sources. The logistics involved in the deployment of concrete block based protective barriers is significant. Despite their cost, they are often left in situ when the forces move on or when the local unrest has settled. In many instances, the formation of barriers _. using sand bags is easier, however, it is also extremely time-consuming and there are instances when the required raw material is not available. It is also well appreciated that the number of filled sand bags required to make an effective barrier against missile attack, "truck bomb" and any other attack using an "Improvised Explosive Device" (IED) makes them an unrealistic- proposition unless there is sufficient manpower and time to assemble such barriers.

While there is an existing great need for a cost effective, flexible and efficient method of protecting personnel and property against the risk of loss of life or injury or damage to buildings, equipment and other resources, respectively, there does not exist presently a rapidly deployable blast attenuating and ballistic proof barrier with protective qualities exceeding those of known concrete and sand bag barriers. Traditionally, these barriers have been used for several applications including blast, ballistic and radiation barriers or shields. The barriers are used in many diverse situations and are considered essential to enhance the capability of both security forces and non-governmental organisations (NGO' s) who provide policing and humanitarian aid in adverse security situations. These barriers may also be used for the protection of strategic installations, such as military encampments and supply depots, buildings such as police barracks, prisons, seats of government and embassies, and national infrastructure including power generation plants, petro-chemical works, telecommunication centres and the media. Additionally, during decommissioning of nuclear power stations, there is a requirement for temporary protection of personnel and local environment from ionising radiation produced by low-grade nuclear material being removed.

With the rise of international terrorism and disparate factions launching terrorist attacks and inciting civil unrest, there is a recognition for the requirement of rapidly deployable barriers which can be adapted to meet varying requirements, including defence against suicide bombers, assassins and individuals or groups utilising "home made" explosive devices or so-called improvised explosive devices.

As previously discussed, barrier assemblies made from concrete block elements have well-appreciated disadvantages including those associated with rapidity of deployment and the possibility of fragmentation causing secondary collateral damage to buildings, equipment and injury to personnel. Additionally, there is a problem of ricochet with small arms munitions and shrapnel.

Filling and stacking sand bags is a slow and labour intensive operation requiring huge amounts of manpower, time and materials. Geotextile bags can be used to speed up this operation, however, they require a metal frame to hold open during filling and the frame is an integral part of the final barrier. One of the major advantages of sand bags is that there is no ricochet or harmful secondary material thrown off upon impact, however, with the integral frames, metal fragments can be ejected from the barrier causing collateral damage.

It will be _. seen therefore that there exists a need for a cost-effective, flexible and efficient apparatus for and method of protecting personnel and property against damage from projectiles and blasts. There is also a need, particularly in the nuclear reprocessing industry for a lightweight barrier to protect life, property and the surrounding environment against (usually) low-level ionising radiation during operations to remove contaminated materials. Currently, this industry shields against radiation using materials comprising concrete, lead and water. The disadvantages of these traditional shielding materials are weight, deployment difficulties and the need for large mechanical equipment to move this type of shielding resulting consequently in long deployment times and significant expense.

In the description that follows, a reference to "attenuating media" is intended to

-A- include the singular and is directed to any material that provides the required reduction or elimination of the effects of incident ballistics, blast forces or radiation energy. The specific examples of water, sand, concrete or lead are not intended to be limiting and it should be appreciated that other suitable materials are or may become available.

It will be appreciated by the skilled reader that although the description of the present invention is directed to blast defence barriers, the invention is not so limited and may be used for defining an area or enclosure within which personnel and certain property or materials may be retained or protected or from which attack or unwanted intrusion may be excluded, at least to some degree.

Considered amongst the things to be excluded arc light arms fire, heavy machine gun fire, attacking forces, blasts from explosions, impact from vehicular assault and ionising radiation. The invention will be described in more detail hereinbelow and may include some of these examples without limitation in further detail.

It is an object of the present invention to seek to alleviate the disadvantages associated with the prior art and to provide a rapidly deployable ballistic and blast defence barrier.

It is further an object of the present invention to provide a barrier element that is conveniently storable and transportable and does not require skilled labour to assemble.

It is a yet further object of the present invention to provide a flexible barrier assembly which may be modified or adapted for a large number of scenarios arising in the field of military endeavour, peace keeping and having additional uses such as that proposed herein for the nuclear industry.

It is a yet further object of the present invention to provide a method of forming a barrier element from component parts and a method of forming a barrier assembly from a plurality of such barrier elements.

Summary of the Invention

According to a first aspect of the present invention there is provided a defence barrier element comprising:

a front wall and a rear wall spaced therefrom by two side walls to form a hollow body;

a base component; and

a top component,

wherein the base and top components are operationally coupled to each of the walls so as to form a self-supporting hollow barrier element and

wherein the barrier element defines an enclosed chamber within which attenuating media is operationally disposed.

In a first construction of the invention, the walls and base and top components of the barrier element are integrally formed, wherein at least one of said walls and top components has at least one aperture defined therein so as to allow the passage of attenuating media into said chamber.

This first construction of the invention provides a barrier element which is immediately ready for deployment and is sufficiently light so at to be manually manoeuvred into position. The attenuating media is added by opening an aperture and filling the chamber, thus providing ballast to the element to resist movement under impact and to enhance the ballistic proofing and blast attenuating or mitigating characteristics of the barrier element.

It will be appreciated that numerous manufacturing techniques may be applied to the formation of unitary hollow articles, one preferred technique used with plastics materials being a rotational moulding technique, referred to as "rota- moulding".

In a second construction, the front, rear and side walls are integrally formed with one of said base component and top component, so as to form an open-mouthed container defining the chamber therein, the barrier element being so sized and shaped as to be nestable for storage and transportation.

In this second construction of the invention, the barrier element has either an open top portion or an open base portion which, in a storage or transportation mode, receives a second barrier element which in turn receives another barrier element, and so on.

In an operational mode either the base component is located in the required position and an open base barrier element is coupled thereto or an open top barrier

• element is located and the top component is secured thereon. The chamber is filled with the selected attenuatin ^χ g& m • edia.

In a third construction of barrier element, the front, rear and side walls are integrally formed as a tubular body to which base and top components are subsequently attached.

In a preferred fourth construction of the invention, the barrier element is constructed from separate front, rear and side wall components and base and top components, each of which may be flat-packed for storage and transportation.

Conveniently, in a storage mode, the top component is nestable within the base component.

Advantageously, each of the components of the barrier element is formed from a plastics or a thermoplastics material having impact characteristics designed to attenuate and propagate the effects of ballistic materials and blast waves impacting thereon.

Conveniently, the components are manufactured from medium or high-density polyethylene or polypropylene which optionally include reinforcing materials therein, for example, polyaramid fibres.

Disposed within the chamber defined within the barrier element, there is provided a bladder for filling with an attenuating material, most preferable water, so as to increase substantially the inertia of the barrier element.

In an alternative arrangement, a honeycomb or similar structure is disposed within the chamber so as to provide cells for said attenuating media. The structure further mitigates blast and ballistic effects and reduces fragmentation of a solid attenuating medium.

The honeycomb or similar structure may be selected from the following forms: a series of vertically disposed columns having a substantially .constant cross- sectional profile; a thin metal or plastics material mesh; a plurality of discrete cells each individually tillable or pre-filled with attenuating media; and an open- celled foam material.

Conveniently, a ballistic deflection or blast attenuation surface is located to abut the front wall component to provide protection thereto and optionally a further ballistic deflection or blast attenuation surface is located to abut the rear wall component of the barrier element.

Alternatively, the front wall component of the barrier element is so shaped as to provide a ballistic deflection surface angled to reduce substantially the impact force incident on the barrier element as a whole. The rear wall of the barrier element may be profiled to attenuate or slow down incident ballistics ideally without ricochet or fragmentation. The rear wall may also be so shaped as to provide an elevated platform for personnel within an enclosure formed by a barrier wall assembly.

Additional ballistic deflection or blast attenuation surfaces may be added to the front and optionally the rear wall components.

Conveniently, the or each ballistic deflection or blast attenuation surface is disposed in a ramped position against said front and/or rear wall components.

A first side wall is provided with an external concave profile and the

corresponding opposite side wall is provided with an external convex profile, the profiles being of a radius to abut or interact with the side wall of an adjacent barrier element and to provide sufficient overlap of barrier wall material without exposing '"weak points". The interaction of adjacent convex and concave side ' wall profiles allows a barrier wall assembly to be shaped at will and to form enclosures.

In an additional arrangement of the fourth construction of barrier element, selected components are profiled to have "'dual purpose'", so that fewer component constructions are required to assemble a barrier element. In this arrangement, the base component may also be used as a top component; the profile of the front wall can be inverted and used as a rear wall; and the first side wall, having an external concave profile, may be used also as the second side wall, where an internal convex profile of said first side wall, corresponding to the external concave profile, becomes the external convex profile of the second side wall.

In a second aspect of the present invention there is provided a method of assembling a barrier element, the method comprising;

positioning a base component on an operational surface; and

locating front, rear and side wall components to engage with the base component, so as to form a chamber.

Preferably, the method includes filling said chamber with attenuating media.

In one particular arrangement of the second aspect of the invention, the method comprises:

positioning a base component having coupling elements for engaging front, rear and side walls, such that when in position the front wall faces the direction of a perceived threat;

locating a profiled front wall component in or against the base so as to engage coupling means therebetween;

positioning a first concave and a second convex side wall in or against the base so as to engage coupling means between each of said side walls, the base and the front wall; and

locating a rear wall component in or against the base to engage respective coupling means therebetween and between said rear wall component and the side wall, so as to form an open mouthed chamber into which is fitted a reinforced bag or bladder suspended within said chamber via lugs, hooks or straps retained at or adjacent the open mouth of the chamber; and

locating a top component or cap to the open mouth of the chamber and receiving or otherwise engaging with coupling means of the front, rear and side wall components of the barrier element and trapping the lugs, hooks or straps of the bag or bladder so as to ensure it remains suspended within the chamber thereof.

Optionally, the base component may be secured to the operational surface.

Advantageously, the operational surface may be prepared or conditioned before the or each base component is positioned thereon.

The operational surface is prepared or conditioned so that the base component lies substantially horizontally to ensure the or each barrier element is substantially vertical in use.

Conveniently, the method includes securing a ballistic deflection or blast attenuation surface to the front wall component and optionally to the rear wall component of said barrier element.

In a third aspect of the present invention, there is provided a barrier wall assembly formed using a plurality of barrier elements, said barrier elements comprising a front wall and a rear wall spaced therefrom by two side walls to form a hollow body and base and top components profiled to engage each of the walls, so as to form self-supporting hollow barrier elements,

wherein the barrier elements define a series of enclosed chambers within which attenuating media is operationally disposed and

wherein components of one barrier element overlap with those of an adjacent barrier element to provide continuity of protection along the length of the barrier wall assembly.

In a first construction of barrier wall assembly, each barrier element is positioned as a discrete element which abuts an adjacent barrier element, the shape of the barrier element overlapping with the shape of the adjacent element to provide said continuity of protection along the length of the barrier wall assembly.

The simplicity with which each barrier element of the assembly may be erected _^ and positioned against an adjoining barrier element facilitates rapid deployment of a barrier wall assembly.

In a second construction of barrier wall assembly, each barrier element comprises a plurality of inter-engaging components, whereby selected components from one barrier element are coupled to corresponding components of an adjacent barrier element so that said adjacent barrier elements are locked together in a barrier wall assembly.

The wall assembly is particularly suitable as a barrier to protect personnel and equipment from incident ballistics and against the effects of incident or adjacent explosions and may be used as an anti-ramming wall to prevent ingress of land vehicle borne bomb ^' attacks. Further applications include as a shield against low- level radiation of the kind encountered, for example, in the decommissioning of nuclear power plants. In a yet further application, a barrier wall assembly may be used as a detonation separator being operationally disposed between fuel or munitions dumps, aircraft or used for any other scenario where ignition may be triggered by deliberate or accidental ignition of an adjacent source.

In a fourth aspect of the present invention, there is provided a method of forming, a barrier wall assembly so as to form a wall or enclosure, the method comprising:

positioning a plurality of barrier element base components such that base component profiles, corresponding to the profiles of side wall components, are closely abutting the adjacent base component so that the desired shape of the barrier wall assembly is at least partially mapped out; and

locating front, side and rear wall components to engage with respective base components so as to form a series of chambers.

Preferably, the method includes filling said chambers with attenuating media.

In a first particular arrangement of the fourth aspect of the invention, the method comprises:

positioning a plurality of base components on an operational surface such that the base component profiles, corresponding to the convex and concave side wall component profiles, closely abut the adjacent base component profiles so that the desired shape of the barrier wall assembly is at least partially mapped out;

coupling the front, side and rear wall components to the respective base components so as to form a series of open-mouthed chambers;

filling said chambers with attenuating media, and

closing the open mouth of each chamber by positioning a top component to the front, rear and side walls thereof so as to complete the sequential barrier elements within a barrier wall assembly.

In this arrangement of barrier wall assembly, each barrier element is positioned as a discrete element which abuts an adjacent barrier element, the shape of the barrier element overlapping with the shape of the adjacent element to provide continuity of protection along the length of the barrier wall assembly.

Preferably, each barrier element is positioned with respect to an adjacent one so as to be angularly displaceable relative to the other along the curved surface of the

respective side walls. In one arrangement, each barrier element is connected via connecting means to an adjacent element. At least one groove is optionally provided parallel to the arcuate length of the curved wall (that is, parallel to the ground or surface on which the barrier elements are located) to receive a connecting runner. The connecting runner is preferably slideably received in the groove formed in the side wall of the barrier element.

Thus, the barrier elements are connectable to one another in a side-by-side relationship and are angularly displaceable relative to one another along said connecting runner parallel to the plane of the surface on which they are located.

Conveniently, the connecting runner has an arcuate portion complementary in shape to the groove in which it is received. The connecting runner may be elongate and conveniently extends an arcuate length commensurate with the depth of the barrier from front wall to rear wall.

In a second particular arrangement of the fourth aspect of the invention, the method comprises:

positioning a plurality of base components on an operational surface in close abutment to the adjacent base component to define a length of barrier wall assembly; and

locating front, side and rear wall components to form a series of chambers,

said front, rear and side wall components being located so as to couple successive adjacent base components and define chambers which overlie at least one of said base components.

In this arrangement, the barrier wall assembly is formed using a plurality of inter- engaging components without relying on the formation of discrete barrier elements.

Conveniently, the attenuating media comprises sand which may be operationally loaded into the chamber of a barrier element via the open-mouth thereof when, the

top component is not in place or via an aperture disposed in said top component.

Preferably, the attenuating media comprises water. Optionally, where additional weight is required, the attenuating media comprises wet sand.

An aperture may be provided in the side or rear walls to allow the attenuating media to escape on decommissioning the barrier wall assembly.

Conveniently, a bag or bladder is suspended in the chamber for sealingly retaining the attenuating media.

The bag or bladder provides a simple and convenient way of retaining water or similar liquid attenuating media within the barrier chamber without leaking and can be retrieved for subsequent use. In one arrangement, a food-grade bag ma}' be used so that potable water is stored within the chamber for emergency or relief use.

Optionally, the attenuating material is concrete. In tins arrangement, a lining membrane is provided within the barrier chamber to prevent concrete adhering to the components of the barrier. Thus, when the barrier is being disassembled on decommissioning, the barrier components may be recovered and removed . Plain concrete barriers may then be left in place. It will be appreciated by the skilled reader that these concrete barrier elements will retain the arcuate side wall profiles and can be formed into (somewhat smaller) barrier wall assemblies.

Optionally, the base component may be secured to the operational surface.

Advantageously, the operational surface ma)' be prepared or conditioned before the or each base _, component is positioned thereon.

The operational surface is prepared or conditioned so that the base component lies substantially horizontally to ensure the or each barrier element is substantial I)' vertical in use.

Where the barrier element is to be located on uneven ground, staging means may

be provided on which the base component is located so as to ensure the barrier element is disposed in a substantially vertical orientation. The staging means, which may comprise a material mat or wedge portions, allows adjacent barrier elements to be in close abutment along the full height of the respective side wall components.

An anchor member may be provided for restricting movement of the barrier element relative to a surface on which it is located. The anchor member may comprise at least one sheet of non- slip material affixed to the barrier so as to engage said surface.

The anchor member may further or optionally comprise at least one ground- engaging anchor adapted to fix the base component in position. The or each ground-engaging anchor may comprise a spike or auger member.

Ideally, the base component is provided with one or more apertures through which the or each ground-engaging anchor passes, thereby fixing said base component to the ground.

Advantageously, the barrier element components include means for securely fastening each component to its adjacent component. This arrangement ensures the barrier element is self-supporting and can be moved as a single unit.

Preferably, each barrier element has at least one attachment member, which may be a lifting eye, so that any suitable lifting means can be attached to said barrier element.

A barrier wall assembly as described enables significant flexibility of deployment. Each individual barrier element component is relatively light and a barrier element can be sited and assembled manually by as few as one person. Where available, a mechanical lifting means can be used to deploy assembled barrier elements into a wall assembly. The attenuating medium loaded within the chamber of the barrier element is normally sufficient to provide the ballast required to hold the element in position, even against impact. If the ballast provided is not sufficient to prevent

moveraent of the barrier when in use, then alternative ballast material can be used, for example, wet sand, concrete or any other suitably dense material.

It will be understood that numerous modifications can be made to the embodiment of the invention described above without departing from the underlying inventive concept and that these modifications are intended to be included within the scope of the invention.

Brief Description of the Drawings

The present invention will now be described more particularly with reference to the accompanying drawings, which show, by way of example only, three embodiments of blast defence barrier in accordance with the invention. In the drawings:

Figure 1 is a side elevation of a first embodiment of blast defence barrier element, comprising front, rear and side walls retained between a ground engaging base component and a top component, each interlocking to form the blast defence barrier element in its operational mode;

Figure 2 is an exploded perspective view of the first embodiment of blast defence barrier element, illustrating the interconnecting arrangement of the front, rear and side walls to the base and top components;

Figures 3a to 3d are a top plan view, a front elevation, a side elevation and a perspective view, respectively of the barrier element, together with further step- height barrier elements having a cross-sectional profile substantially similar to the top component of the blast defence barrier element;

Figure 4 is a perspective view of a barrier wall assembly comprising blast defence barrier elements and step-height barrier elements, arranged so that side walls of successive barrier elements abut one another to present a substantially continuous barrier wall assembly;

Figures 5a to 5f are perspective views of a base component, a front wall

component, a rear wall component, first side wall component, a second side wail component and a top component of a second embodiment of blast defence barrier element;

Figure 6 is a perspective view of the second embodiment of barrier element in an operational mode but with its top component removed to illustrate a chamber therein to be filled with weighting or blast attenuating media;

Figure 7 is a perspective view of a barrier wall assembly comprising blast barrier elements of the second embodiment, arranged as a corner section of a wail, and having components removed so as to illustrate the location of liners within the chambers for containing the weighting or blast attenuating media;

Figures 8a to Sf are a top perspective view, a cross-sectional side elevation and. a detailed view of the cross-sectional side elevation of a dual purpose base and top component; a perspective view of a dual purpose front and rear wall component; a perspective view of a dual purpose side wall component and a bottom perspective view of a blast attenuating surface of a third embodiment of blast defence barrier element;

Figures 9a to 9d are views of additional components for constructing step-height barrier elements including: a perspective view of a dual purpose front and rear wall component; a perspective view of a dual purpose side wall component; a top perspective view of a first upper intermediate component for use with discrete barrier element formation; and a top perspective view of a second upper intermediate component for use with formation of inter-engaging barrier elements; ¹ and

Figure 10 is a perspective view of a barrier wall assembly comprising blast defence barrier element components and step-height barrier element components, arranged so that successive components interlock with corresponding adjacent components to form chambers defined over one or more adjacent base components to present a substantially continuous barrier wall assembly.

Detailed Description of the Preferred Embodiment

Referring to the drawing and initially to Figures 1 and 2, a first embodiment of blast defence barrier element 1 is shown. The barrier element 1 comprises six major components which, when assembled together, form a barrier element having an enclosed chamber C. The barrier element 1 comprises a ground- engaging base component 2, a front wall 3, a rear wall 4, a concave first side wall 5, a convex second side wall 6 and a top component 7, each of which have profiled portions adapted to engage with adjacent components so that the element is self-supporting.

The components are fabricated? using ballistic and blast resistant or attenuating materials selected from any one or more of a number of suitable materials known to those skilled in the art, including plastics materials, such as polyethylene or polypropylene, and composite materials, including those incorporating high tensile strength polyaramid fibres, for example, Kevlar ™.

The base component 2 is formed as a tray having peripheral walls 10 and lands 11 so sized and shaped as to retain the correspondingly shaped engaging portions of the front, rear and side wall components 3,4,5,6. The peripheral walls 10 and lands 11 corresponding to the front and rear walls 3,4 are parallel to one another and spaced apart by arcuate sections of the peripheral walls and lands corresponding to the spaced apart side walls 5,6. The side wall radii are chosen as being equal for engaging and moving against abutting barrier elements.

The front wall component 3 includes an external blast face 4 upon which expected projectile impact or blast force is incident. The front wall component 3 includes side wall engagement profiles 15 along each of its upright edges and lower and upper locating tabs 16,17 for abutting and engaging with the base and top components 2,7, respectively.

The rear wall component 4 is of similar size and shape to the front wall component 3 and includes a major face which optionally includes recesses such as hand and foot holds. Optionally or additionally, the rear wall component includes

a platform on which a person may stand. As will be described hereinbelow, the reai- lace component may also be designated as an incident blast face or may comprise materials adapted to absorb incident projectiles or shrapnel, lessening the risk of injury from ricochet and rebound. The rear wall component 4 also is provided with side wall engagement profiles 20 along its upright edges and lower and upper locating tabs 23,24 for engaging with the base and top components respectively.

The first and second side walls 5,6 are formed ideally of the same material as the front and rear walls 3,4 and include front and rear wall engagement profiles 26 along each of their upright edges. Each side wall also includes lower and upper locating tabs 29,30 for abutting and engaging with the base and top components 2,7, respectively. The first side wall 5 is profiled to present a concave major outer surface and the second side wall 6 is correspondingly profiled to present a convex major outer surface. The radii of these surfaces are chosen as being equal so that the concave side wall of a one barrier element receives, in an abutting arrangement, the convex side wall of an adjacent barrier element, as will be described in more detail with respect to Figure 4.

The top component 7 is of a similar configuration to that of the base component 2 but of smaller dimension corresponding to the distance between the front and rear walls 3,4 and is adapted to receive the upper engagement tabs 17,24,30 of the front, rear and side walls 3,4,5.6. In addition to the peripheral wall 32, the top component is also provided with a second "inner" peripheral wall (not shown) spaced from the "Outer" peripheral wall 32, so that the upper engagement tabs 17,24,30 are constrained therebetween.

The barrier components may be stored as a kit of parts so that individual barrier elements may be taken from storage and assembled one at a time, however, where there is a requirement for multiple barrier elements to be erected, the barrier components may be stored for transportation in multiples so as to maximise storage space. With reference to Figures 2 and 3a to 3d, it will be appreciated that a barrier element 1 .may be erected by a single person, although ^' the job is more easily accomplished with two. Assembly is commenced by positioning the base

component 2 in the required position and setting it substantially horizontally.

This may be accomplished by either fixing the base component on ^' a hard horizontal plane, such as pavement, or positioning it in relatively soft material, such as sand, and manipulating or "bedding in" the base until it is substantially horizontal. Measurement may be taken by spirit level or, in an un-illustrated embodiment, a pair of securely bonded spirit level vials are secured in the lands 11 of one of the shaped peripheral walls 10 for engaging the front and rear components and in the lands 11 of one of the shaped engaging peripheral walls 10 for engaging the side wall components, to provide immediate visual indication that the base is horizontal. One or more holes 34 may be provided in the inner tray portion of the base component 2 so that ground engaging spikes or threaded auger elements (not shown) can be used to secure the base component to the ground. Where it is not possible to bed the base component into a horizontal position, staging mats or wedges (also not shown) may be used to ensure horizontal orientation. Once the base is properly positioned and/or secured, the remaining assembly of the barrier element is exceptionally straightforward. As each of the front, rear and side walls include engagement profiles 15,20,26 along each of their upright edges, so as to secure each wall component to their adjacent wall component, visual inspection of the respective engagement profiles will indicate the most appropriate form of assembly. In most instances, it will be preferable to erect one of the side walls 5,6 which, due to their convex or concave shape, will stay in an upright position when positioned in the base component. Either the rear wall 4 or front wall 3 is then positioned in the base 2 and its engagement profile 15,20 is received by or couples with the engagement profile 26 Of the side wall which, being disposed at substantially 90° to one another, are together again self-supporting. The second one of the side walls is then put in position so that it's base engaging profile 29 engages the corresponding profile 10, 1 1 of the base component 2 and it's edge profile 26 couples with the corresponding edge profile 15,20 of said rear or 'front wall. The other of said rear or front walls is then brought into position and either coupled with the upright edge profiles 26 of the spaced apart side walls and slid downwardly so that it's base engaging profile 16,23 locks with the corresponding edge profile 10,1 1 of the base component 2 or said remaining one of the rear and front walls is coupled to the upright edge profile 26 of one of the side walls and to the base component

before being manipulated so as to engage the upright edge profile 26 of the other side wall to form an open- mouthed chamber C. The upper locating tabs 17,24,30 of each of the front, rear and side walls protrude from the respective wall components and are arranged to be sliding received between the outer and inner 32 peripheral walls of the top component 7 which is positioned to close the open- mouthed chamber C.

Before the top component 7 is put in position, the chamber C is filled with attenuating or blast mitigating media which can be selected from a number of convenient materials including, for example, water, sand or concrete. Each medium can present it's own set of challenges, however, sand or water tend to be the most readily available blast attenuating media in most environments. WiLh sand, the chamber C can be filled manually or by tipping bucket loads into the open mouth via a powered lifting means, such as a conveyor arrangement or, most conveniently, a general purpose work vehicle, for example, a tractor or digger. When the barrier element is to be disassembled, the reverse procedure described above is used and the sand is simply released, at which stage the base component is dug out and retrieved. Where concrete is used as the attenuating medium, lining material may be used to separate the base, front, rear and side wall components from the concrete which is poured into said open-mouthed chamber C. When the barrier element is decommissioned, the top and wall components of barrier element may be removed without the . concrete adhering to them and, advantageously, the resultant moulded concrete shape maybe used as a barrier element in it's own right. Water may also be used as an attenuating medium, however, unless the respective base front, rear side walls and top components are sealingly engaged to one another, the water will leak out of the barrier element or, over time, with evaporate from the chamber C.

Where supply and deployment conditions allow, alternative attenuating media can be used accordingly to the application considered. For example, water ma)' be substituted for a liquid having a higher density or better blast energy mitigating properties or radiation absorbing characteristics. Further materials or arrangements of material may be placed in the chamber, including lead composite material plates disposed parallel to the front wall component or honeycomb or cell

stmctures within which different media may be located.

In a preferred arrangement of the invention, a media containing bag is positioned within the chamber and filled in situ. Where water is used as the attenuating medium, the bag may be sealed to prevent evaporation. In certain scenarios, for example, where troops are deployed in remote desert environments or where relief agencies are positioned, it would be advantageous that the media containing bags are food-grade bags so that potable water is stored within the barrier elements and can be used if other stocks become depleted.

The media containing bags are retained in position by providing loops or straps thereon for engaging with the upper locating tabs 17,24,30 or slots cut therein of at least one of said front, rear and side walls 3,4,5,6. Conveniently, when the media is to be loaded into the bags, the bags are held in an open-mouthed configuration using said locating tabs.

Figures 3a to 3d schematically illustrates a completed barrier element 1, including additional step-height barrier units 50 which, essentially comprise mini barrier elements which can be formed as solid units, open tubular constructions, open- _, mouthed containers or as elements assembled from individual components in a manner similar to that of the preferred embodiments of barrier element described herein. The step-height barrier units 50 normally have a cross-sectional profile identical to that of the top lid component 7 of the barrier element and may be provided to add significantly to the height of a barrier wall assembly, such as that illustrated in Figure 4. The step-height units 50 may simply sit on the top component 7, on each other or may be fixed in position by a locking mechanism (not shown). Optionally, a unitary open tubular step-height unit, having an end profile adapted to engage or receive the upper locating tabs 17,24,30 of the barrier element walls, may be positioned in place of the barrier lid component 7 which may be used to close the upper open end of said open step-height unit. Alternatively, an open-mouthed. step-height unit is placed on the open mouth of the barrier element chamber or the open end of said open tubular step-height unit.

Where the step-height unit is formed as a unitary body, it can be hollow with

apertures for filling and emptying. Where the unit is a solid unit, it must of sufficient density to attenuate blast effects while being resistant to movement. With open or assembled step-height units, appropriately sized media containing bags are provided. These bags either sit loose into the step-height units or are secured therein as described hereinabove.

Although not specifically illustrated, locking mechanisms are optionally provided for securing each of the components together and for securing step-height units to the assembled barrier element or to one another. Ideally, plastics material over- lever lockin ^x ga devices are used.

The lid component 7 and/or the ^' uppermost surface 52 of a step-height unit may be provided with threaded holes 54 for receiving a lifting eye, so that complete barrier elements (with or without step-height units) can be lifted and placed in position by a mechanical lifting means. Optionally, gripping bars are moulded into the upper regions of the front and rear wall components for receiving lifting hooks or straps.

Referring now to Figure 4, a barrier wall assembly is illustrated comprising a plurality of barrier elements 1 , including step-height barrier units 50, which have been placed in close abutment to one another so as to form a substantially impermeable wall. By placing the concave side wall 5 of one barrier element against the convex side 6 wall of an adjacent barrier element, said barrier elements interlock to provide stability, strength and flexibility to the barrier wall assembly. By virtue of the rounded profiles of said interlocking convex and concave walls 5,6, the barrier wall assembly may be formed in a wide range of shapes, including enclosures-.- This is of particular relevance for protecting buildings, troop encampments, gun emplacement, ammunition stores and fuel dumps. When providing radiation shielding the barrier wall assembly may be formed around, for example, containment vessels or a collection of barrels filled with low-grade nuclear _. waste awaiting transport for reprocessing or burial.

Referring now to Figures 5a to 5f and Figures 6 and 7, a second embodiment of blast defence barrier element 100 is shown. As with the first embodiment, the

second embodiment of blast defence barrier element 100 comprises a gromid- engaging base component 102, a front wall 103, a rear wall 104, a concave first side wall 105, a convex second side wall 106 and a top component 107, each of which have profiled portions adapted to engage with adjacent components so that the element is self-supporting and which forms a barrier element having an enclosed chamber C.

The components are again fabricated using blast resistant or attenuating materials selected from any one or more of a number of suitable materials known to those skilled in the art. Accordingly, manufacturing techniques may be one or more of the many techniques available to the skilled addressee, including rotational moulding and, in the case of constant cross-sectional components, such as the front, reai- and side wall components, extrusion.

The base component 102 is formed as a block having a pair of rectangular receivers 110 for receiving correspondingly shaped engaging portions of the front and rear wall components 103, 104. Further circular receivers 111 are provided to engage with lower locating tabs of the side wall components 105, 106.

The front wall component 103 includes an external blast face 114 upon which expected projectile impact or blast force is incident. The blast face 114 is ideally integral, however, a separate blast face attachable to the front wall component 103 and rear wall component 104 is realisable and thus facilitates the manufacture by extrusion of the front and rear wall component 103,104. A separate blast face 114 also allows for more convenient storage and transportation. The front wall component 103 further includes side wall engagement profiles 115 along each of its upright edges' and lower and upper locating tabs 116, 117 for abutting and engaging with the base and top components 102, 107, respectively.

The rear wall component 104 is of similar size and shape to the front wall component 103. The rear face component may also be designated as an incident blast face and is optionally provided with a blast face portion. As with the front wall component 103, the rear wall component 104 includes side wall engagement profiles 120 along it's upright edges and lower and upper locating tabs 123,1.24

for coupling with corresponding receivers in the top and base components. The first and second side walls 105,106 are formed ideally of the same material as the front and rear walls 103,104 and include front and rear wall engagement profiles 126 along each of their upright edges. Each side wall also includes lower and upper locating tabs 129,130 for abutting and engaging with the base and top components 102,107, respectively. The top component 107 is configured to sit onto the upper edges of the front, real- and side wall components 103,104,105,106 and is provided with a number of receivers 132 configured to align with the upper locating tabs 117,124, 130 of said front, rear and side walls.

With reference to Figure 6, it will be appreciated that a barrier element 100 may be erected by a single person. Assembly is commenced by positioning the base component 102 in the required position and setting it substantially horizontally. One or more holes (not shown) may be provided in the base component 102 so that ground engaging spikes or threaded auger elements can be used to secure the base to the ground. Staging mats or wedges may also be used. As each of the front, rear and side walls 102,103,104,105 include engagement profiles 115,120,126 along each of their upright edges, so as to secure each wall component to their adjacent wall component, visual inspection of the respective engagement profiles will again indicate the most appropriate form of assembly.

As will be seen from Figure 6. the edge profiles 115,120 of the front and rear walls 103,104 are trapped by the edge profiles 126 of the side wall components 105,106 when the barrier element 100 is assembled. Thus, assembly will often begin with one of either the front or rear walls 103, 104. It is suggested that the front wall component 103 and blast face 114 is first fixed to the base component 102 by inserting the lower locating tab 116 of said front wall 102 into the corresponding receiver 1 10 in the base 102. As the blast face 114 has a ground- engaging surface approximately in line with the ground-engaging surface of the base 102, the front wall component 103 is self-supporting in most circumstances. A first one of the two side ^' walls components 105,106 is then fitted by coupling the upright edge profile 126 to the corresponding edge profiles 115 of the front wall component and inserting the lower locating tab 129 thereof into the

corresponding receiver 11 1 in the base component 102.

The reai- or front wall component 104 is then brought into position and coupled with the upright edge profile of the selected side wall and the lower locating tab 123 locks with the corresponding receiver 110 in the base component 102. The remaining one of the side walls 105,106 is positioned against the upright edge profiles 115,120 of the front and rear walls before being manipulated or slid downwardly so that the lower locating tab 129 thereof engages the corresponding receiver 111 in the base component 102 to form an open- mouthed chamber C. The upper locating tabs 117,124,130 of each of the front, rear and side walls protrude from the respective wall components and are arranged to be sliding received within the corresponding shaped receivers 132 of the top component 107 which is positioned to close the chamber C.

As before, barrier elements may be positioned to form a wall or enclosure and may be disposed in arrangements such as that illustrated in Figure 7, so as to round a comer without presenting a "weak point".

As with the first embodiment of blast defence barrier, the chamber C is ideally filled with attenuating media. As before, a sealing arrangement may allow for water to be used without leaking, however, the preferred arrangement is to use a media containing bag B, as illustrated in Figure 7. A plurality of tab engaging straps S is fixed to the upper region of the bag B to prevent it collapsing into the chamber C. A port P is provided in the bag to allow the bag to be filled and

• emptied by coupling a feeding tube thereto. The bag B may also be provided with internal chambers to prevent explosive dispersal of attenuating media in the event of wall penetration or blast rupture.

Although not illustrated or described specifically in the foregoing, the invention is intended to encompass in its remit, unitary hollow blast defence barrier elements defining a chamber therein for filling with attenuating media. For example, a shaped body formed by a rotational moulding technique is provided with filling and, optionally, draining holes for the attenuating media, irrespective of whether water, sand, concrete or any other medium is chosen. As described hereinabove,

any appropriate manufacturing techniques may be applied, however, some constructions are more appropriate to particular techniques. For example, where the front, rear and side walls are formed as a single tubular body, extrusion would be a convenient manufacturing process. Indeed, an interior cell-like (honeycomb) structure could be extruded with the body, thus providing a means • of using different attenuating media within a barrier element without mixing them. It is thought that a cellular structure within the barrier element chamber provides enhanced blast mitigation or attenuation.

The barrier element may also be made as an open-mouthed container with either the base component or the top component omitted. Each arrangement will have its own advantages and disadvantages, primarily relating to the ease with which the base component may be secured to the ground and the manner in which the chamber is filled. An open-mouthed construction also raises the issue of nesting for storage and transportation. Where the barrier element has a consistent cross- sectioned profile, nesting is not an option, however, certain constructions of barrier element will allow this.

In another unillustrated arrangement, the barrier elements are provided in pairs, the first being larger than the second barrier element so that in a storage or transportation mode, the second barrier element is nestable within the first. Ideally, where the barrier elements have concave or converse side walls, as with the illustrated embodiments, the radii of said walls remains constant but the width of the front, rear and . side walls are reduced. This allows for a barrier wall assembly to be constructed as before with every alternate element in the wall being slightly recessed, when viewed from the front or the rear.

The barrier element components may be formed with a single wall thickness or

•may comprise double skin components, depending on the strength-to-weight characteristics required. Where a single skin wall component is used, the wall thickness is usually in the region of 10mm. Double skinned wall components will have thicknesses ranging from 5mm to 10mm, with 6mm being typical. The current exemplary material for said wall components is medium-density polyethylene.

Again, it will be appreciated that there are significant opportunities for adapting the , barrier elements described herein and the step-height barrier unit 50 for additional functionality. This is particularly so of the step-height units which can be function-specific. In one arrangement, gun sight slots are formed in the units to allow security personnel to survey beyond a barrier wall assembly without undue exposure. Additionally, slots, holes, handles and other cavities within the side or top surfaces of a step-height unit or a top component of a barrier element allow for further elements to be attached to a barrier element or wall assembly. For example, step-height units having shaped receivers can be used to support roof truss elements to which roof plates may be secured. Such roof plates are ideally formed from the barrier element material and provide protection from sniper fire and shrapnel. The roof plates are particularly useful where a cordon or corridor is provided for protecting personnel, "VIPs" or witnesses walking from one safe environment to another, for example, from an armoured vehicle to a building.

Referring now to Figures 8 a to 8f, a third embodiment of blast defence barrier element 200 is formed from as few as three separate components, that is, a dual purpose base and top component 202, a dual purpose front and rear wall component 203 and a dual purpose side wall component 205. The components are again fabricated using blast resistant Or attenuating materials selected from any one or more of a number of suitable materials known to those skilled in the art. In this embodiment, the components are double-skinned, blow moulded components, however, other manufacturing techniques are available to the skilled addressee.

The base component 202 is formed as a shaped platform having a first pair of receiving apertures 210 for receiving frusto-conically shaped locators of the front wall components 203 and a second pair for the rear wall component. A series of three receiving apertures 211 is provided to locate a side wall component 205 at a number of different positions along the base component, as will be described in more detail hereinbelow. The underside of the base component has corresponding side wall and front and real' wall receives therein, as illustrated in Figure 8b. This allows the base component 202 to act also as a top component. Between the front and rear wall receives 210 on the underside of the base component a slot 213, as

detailed in Figure 8c, is provided for receiving a coupling portion of a blast deflection or attenuating surface 214, as will be described in more detail with reference to Figure 8f.

The front wall component 203 includes side wall engagement profiles 215 along each of its upright edges and lower and upper locating tabs 216, 217 for engaging with corresponding receivers 210 of the base and top components 202. The front wall component 203 is shaped so that it can be inverted to form the rear wall component also.

The side wall component 205, illustrated in Figure 8e, also has a dual purpose in that it can present a concave major outer surface when positioned at a corresponding -concaved edge profile of the base component 202 and a converse major outer surface at the opposite corresponding convex edge profile of the base component and includes lower and upper locators 229, 230 for engaging with the corresponding receivers 210 of the base and top components. The side wall component 205 also includes front and rear wall engagement profiles 226 on the concave surface thereof and further front and rear wall engaging profile 227 on the convex surface thereof.

The blast deflection or attenuating surface 214 comprises an additional optional component having a substantially triangular cross-section. This component can be placed before the front and rear walls 203 to provide ballistic and blast protection thereto. The deflection surface 214 is secured to the base component 202 by trapping a rectangular projection 235 within the receiving slot 213 of said base component 202.

To form a discrete barrier element 200 from these components, the following steps are made: if deflection or attenuating surfaces 214 are required these are positioned on the selected surface so that the projections thereof are trapped within the receiving slots 213 before a base component 202 is located on said surface and optionally secured thereto; a first side wall component 205 defining an outer concave surface is secured to the base 202 by engaging frusto-conical locators 229 into corresponding receivers 21 1 in the base component along its

corresponding concave edge. A front wall component is then positioned either as the front wall or as the rear wall of the barrier element 200 by securing locator tabs 216 into the corresponding receivers 210 of the base component 202 and a side wall engaging profile 215 into the corresponding receiver profiles 227 of the side wall. The other of said front or rear walls is then positioned. The convex second side wall 206 is then secured to the base component and to the front and rear walls by inserting the locator tabs 229 into the corresponding receivers 21 1 along the converse edge of the base component and receiving the front and rear wall engagement profiles 215.

A second base component 202 is then utilised as a top component by positioning it over the open-mouthed container thus formed, and engaging the respective upper locating tabs 217, 230 of the front, real" and side wall components in the corresponding receiver apertures 210, 211 to form a barrier element having an enclosed chamber C.

Referring to Figures 9a and 9b, step-height barrier units 250 may be added to the discrete barrier elements 200 by adding a dual purpose front and rear wall component 253 and a dual purpose side wall component 255 to the existing barrier element 200 by coupling the step-height components 253, 255 to the top component 202 thereof and completing the unit by adding a further top component 202 thereto. As an alternative, as intermediate component 260 as shown in Figure 9c is used in place of the top component 202 of the barrier element 200 and the dual purpose step-height wall components 253, 255 are secured to the intermediate component. Additional step-height units may be built up in this way before the increasingly large chamber C is closed using a top component 202.

By having discrete barrier elements, a barrier wall assembly may be constructed substantially as described hereinabove with respect to the fist and second embodiments. Accordingly, a barrier wall assembly may be formed as an enclosure or of any convenient shape.

Where flexibility of formation of a barrier wall is not critical or where a straight

run of barriers is required, an alternative barrier wall configuration may be considered. As before, a series of base components 202 are set down and deflection surfaces 214 fitted, as required. A first side wall component is slotted into the receivers adjacent the concave edge of the base portion and front and rear wall components 203 are secured thereto by coupling the edge profiles 215 thereof in the slotted receiving profiles 227 of the side wall 205. The second side wall component is then fitted and receives the front and rear edge wall profiles 215 in the inner slotted profile 226 to complete the open-mouthed container configuration. Subsequent front and rear wall components are used to form additional open-mouthed containers which can then be closed by placing top components thereon. It will be appreciated that as each additional container is formed, it will be offset with respect to the base and top components.

Step-height barrier units 250 may also be formed in the same manner as the above barrier elements 200. In such a construction, as substantially U-shaped intermediate component 270, as shown in Figure 9d, is used in preference to the intermediate component 260 having a substantially identical peripheral profile to that of the base or top component 202. The U-shaped intermediate component includes a coupling profile 272 at the end of each leg of the U-shape and corresponding profile receivers 274 on the convex edge thereof so the component may be coupled to an adjacent one in a barrier wall assembly.

Finally, with respect to Figure 10, a barrier wall assembly comprises a plurality of barrier elements 200 and step-height barrier units 250. Each barrier element comprises a base component 202, front and rear wall components 203 and side wall components 205 to define a chamber C. Step-height units 250 comprise U- shaped intermediate components 270 which operationally couple the front, rear and side walls components of the barrier elements to the corresponding front, rear 253 and side 255 wall components of the step-height units 250 which are capped off by top components 202. Deflective surfaces 214 are also positioned along the front wall side of the barrier.

As with the first and second embodiments of blast defence barrier, the chamber C is ideally filled with attenuating media. As before, a sealing arrangement -may

allow for water to be used without leaking, however, the preferred arrangement is to use a media-containing bag B.

It will of course be understood that the invention is not limited to the specific details described herein, which are given by way of example only, and that various modifications and alterations are possible within the scope of the appended claims.