GB2270938A - Earth support system for trench warfare - Google Patents

Abstract

A collapsible earth trench support structure is provided. It comprises side panels 14 for application to the sides of trench walls and cross bars for jacking the sides apart and onto the trench walls. The bars are provided to the side walls so that the structure can be collapsed for insertion and removal. The structure is made up of a metallic tubes and is clad with panels which are fire resistant, e.g. of Al - sheathed polyurethane. <IMAGE>

Description

Improvements in Earth Support Systems This invention relates to earth support systems which are especially suited for providing underground shelters or "dug outs".

The use of trenches for the protection of soldiers during battle is well established, and has been for over a century.

The first of such trenches were open diggings, and offered refuge to soldiers and protection from gun shot, but open trenches, if the sides are not to collapse, have diverging sloped walls. Trench support systems have been developed to enable trenches to have steeper sides (requiring less digging) to provide more protection.

Most modern trench support systems provide two "bays" namely a firing bay and a shelter bay. Occupants can fire weapons from the firing bay and when being fired upon, can take shelter in the shelter bay. Each of the bays has a roof covering, but the firing bay has a window or windows through which the occupants can fire their weapons, and the occupants will normally be standing when in the firing bay and seated or crouched when in the shelter bay.

The British army uses a system referred to as the 'Ridley Tin' to provide protective dug outs. In a Ridley Tin, a main earth support system consists of a housing made up of corrugated iron sheet supports formed with U-shape. The supports are variously arranged to support the sides of a trench which has previously been dug by soldiers or by a digger. For example, a trench might be designed to have one central shelter bay and a fire bay at each end. In this case, the sides of the trench at the shelter bay are supported by positioning corrugated supports so that the sides thereof engage and support the sides of the trench and curved portions define the roof whilst at the fire bay ends the supports are arranged with their sides again at the sides of the trench but with the curved sections supporting the ends of the trench.The curved roof of the shelter bay is covered'with sand bags and the fire bays have pickets, which define a raised roof, covered by more sand bags, but leaving at least one firing aperture.

The Ridley Tin has been used for a hundred years, and it is now considered outdated and ineffective. It takes on average fourteen hours to construct a dug out with Ridley Tin and during the process of digging out there is no support for the trench walls to protect the digger or diggers. Further, Ridley Tin dug outs have shown themselves not to be sufficiently effective against the effects of bomb-blasts.

Another trench support system in use consists basically of two thick metal sheets, which are placed in the trench and jacked apart into the trench walls so as to form a reinforced space in which soldiers can shelter. A major disadvantage of this system is that it is extremely bulky and heavy, and therefore is not well suited for transport and repeated installation, which are features which are highly desireable in a trench support system.

Ideally, a trench support system should be light, compact, adaptable, reusable, highly resistant to the various weapon effects to which it may be subjected to during battle; it should also, be easy to erect.

The present invention adopts an entirely new approach to trench support systems and seeks to provide at least in its preferred forms a system which incorporates these features and has numerous advantages over previously used systems.

According to the present invention, there is provided a collapsible earth support structure for a trench, wherein the structure comprises sides for application to the sides of the trench, said sides being pivotally connected to cross bars enabling the structure to be collapsed to a flattened state in which the sides are close together in which condition it can be transported and an opened out state in which the sides are jacked apart by the cross bars.

Preferably, the structure when erected has panels at said sides.

The framework may additionally comprise cross frames hinged to the sides and swingable between a stored position wherein they are close to the sides and a jacking position in which they extend between the sides.

The framework and cross frames may comprise tubes of metal which are connected to each other and/or to the panels by the use of connectors.

Preferably, the panels are attached to the exterior of the support structure so that pressure exerted on the exterior of the structure by the trench walls is transmitted directly to the framework.

The structure is collapsible to enable it to be conveniently handled and transported. Erection and installation of the structure is simple and quick.

The trench support structure is preferably designed to withstand weapon effects during warfare.

The structure may comprise a shelter bay portion and there may be an ancillary framework to define a fire bay portion.

To provide a complete dug out, the structure preferably is used with concertina-action containers which are filled to create blocks, as described in Patent Application No. WO 90/12160, in place of conventional sandbags, such blocks providing above-ground substantial walling arrangements.

These concertina-action containers shall be referred to in the remainder of this document as bastion blocks.

The panels should be highly resistant to weapon effects, while being as light as possible to allow the system to be carried and installed quickly with a minimum amount of human effort. Panels comprising aluminium alloy cladding and a fire-retardant polyurethane core can survive very large transient loads such as those delivered by buried bombs, and are therefore suitable for the structures of the invention.

Such panels can be used as roof panels and when so used may be provided with a further cladding of ceramic tiles to protect them against fragments of airborne projectiles.

An embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings, wherein Fig. 1 illustrates in exploded oblique view a trench support structure according to the embodiment of the invention; Fig. 2 shows in front view the framework and bastion block construction shown in Fig. 1; Fig. 3 shows in end view the framework shown in Fig. 1; Fig. 4 shows in plan view the framework shown in Fig. 2 but from which the bastion blocks have been removed; Figs. 5, 6 and 7 show in front, end and plan views respectively the framework and panel attachments shown in Fig. 1; Fig. 8 shows, to a enlarged scale and in oblique view, the framework shown in Fig. 1; Figs. 9A to 9H illustrate various connectors for use in the framework shown in Fig. 1;; Figs. 10A and 10B respectively show vertical sections of the side and roof panels shown in Fig. 1; Fig. 11 shows in cross section a connector for attaching panels to the framework shown in Fig. 1; Fig. 12 shows an unfilled bastion of a type which may be used in the present invention; Fig. 13 shows a sling whereby the trench support structure shown in Fig. 1 may be carried; and Fig. 14 shows in cross section another connector for attaching panels to the framework shown in Fig. 1; Referring to Fig. 1, a trench support structure according to an embodiment of the invention comprises a framework 2, illustrated in dotted lines, side panels 4, end door panels 5 and roof panels 6. The framework 2 comprises steel tubes and cast iron connectors.

The structure may be divided into two distinct portions; that of a shelter bay 8 and a fire bay 10. The shelter bay 8 comprises a framework 12 in the form of a rectangular prism, horizontal side panels 14, a (not shown) roof panel 16, end door panels 5 and floor panels. The fire bay 10 comprises a rectangular framework 20, vertical side panels 22, a roof panel 24, bastion blocks 26 and an end panel 28.

The framework structure is shown in Fig. 8. The shelter bay framework 12 and the fire bay framework 20 interconnect to form a complete and rigid box-like structure. The shelter bay framework 12 comprises cross bars or lateral supports 30, longitudinal rails or supports 32, and cross frames 34, 36 and 38, and optional vertical supports 40. The lateral and longitudinal supports are connected at the eight corners of the shelter bay by means of aluminium sand cast clamps 42 such as the four way clamp 43 shown in Fig. 9C.

The side panels 14 are attached to the lateral supports 30 by means of the peripheral connector 44 shown in Fig. 11, which consists of an L-shaped metal extrusion having a semi-tubular portion 46 and flat end portions 48 and 50. Each peripheral connector 44 encloses the lateral support 30 so that the tube 30 is held in the semi-cylidrical recess 52 and the connector ends 48, 50 are to opposite sides of and at the peripheral edge of the panel. To secure the connection, a bolt is inserted through bolt-holes present in the panel 14 and the end portions 48 and 50. The bolt has an allen-key head, and is fixed in place by the screwing on of a nut followed by tightening with an allen key, which is conveniently the only tool required for the erection of the complete trench support structure.

The frames 34, 36 and 38 each comprise four tube sections 54 and 56 connected to form a rectangle by for example a clamp 57 af the type shown in Fig. 9A at each corner. The vertical sections 54, 55 are slightly shorter than the height of the vertical supports 40, if present, so that the frames 34, 36, 38 34, 36 and 38 can lie between the longitudinal supports 32 in a stored postion. The frames 34, 36, 38 are attached to the side panels 14 by means of a surface connector 56, as shown in Fig. 14 also having a semi-tubular portion 58 and flat ends 60 and 62, which form coplanar flanges. Surface connectors 56 are fitted around one of the vertical sections 54 of the frames and are secured horizontally in place on the surface of the side panel 14.Two frames 36 and 38 are hinged to one side panel 14 in central and end positions, while the third frame 34 is hinged to the other side panel at the opposite end thereof. In the flattened condition of the framework, the frames are hinged, in a stowed position to lie parallel to the side panels 14.

Both the peripheral and surface connectors 44 and 56 allow the tube sections held therein to rotate freely in the connector for the purposes described below.

The basic trench support system described can be extended in that shelter bays and fire bays can be added in a plurality of configurations, to create a trench network of any desired length.

To achieve this end, all end panels 5 can function as doors which open outwards, so that added bays can be accessed.

Door panels 5 at end bays would not be openable due to the proximity of the trench wall.

In its flattened state, the shelter bay framework sides are closer together.

The corner clamps 42 allow rotational movement of the cross bars 30 around the axes of the longitudinal supports 32.

These features of the connectors 42 allow the shelter framework to proceed from rectangular to rhomboid section as the framework 12 moves to the collapsed condition.

Conversely the framework 12 and side panels 14 can be folded open from the flat condition, by reversing the operation.

To rigidify the structure in its open position, the frames 34, 36 and 38 are rotated from their stowed position to brace the open structure. The frames are swung out in the manner shown in Fig. 4, along the paths indicated by arrows 64, 66 and 68. In this position, the frames are braced against the surfaces of the four longitudinal supports 32 to lock the structure in its erected state. This structure is highly rigid, and is sufficient to withstand large loads from all sides without collapse.

The structure may if desired be further rigidified by the process of attaching the end doors 5 to the structure. Also, the frames 34, 38 at the ends of the shelter bay 8 are each provided with door hinge components 70 as shown in Fig. 9D on the vertical section 55, the side panel 14 being provided with corresponding hinge fittings 72 as shown in Fig. 9E.

The end door is provided with corresponding hinge pinning components 74 as shown in Fig. 9F. The insertion of the hinge pin 76 as shown in Fig. 9G through the circular apertures of the hinge counterparts 70 and 72 both serves to attach the end door to the framework 12 and attach the frame to the appropriate panel 14, thus preventing any further rotation of the end frames.

Alternative fixing of the end frames 34 and 38 in the panels, and fixing of the central frames 36 can be acheived by the positioning on the opposed panel of further and opening connectors similar to the surface connectors, except with one end 62 rotatable around a hinge provided at the corner 78.

The hinge allows the connector to be opened to receive the vertical section 55 of the frame and closed thereon, then secured by the fitting of a bolt through the connector and a hole provided in the panel, which is fixed in place by use of the aforementioned allen key.

In use, the entire trench support structure in flattened condition may be transported to the proposed site by any military transport vehicle. It will be of flooded in its flat condition, after which the trench is constructed by one or more soldiers or by a digger such as an excavator. A standard trench comprising one shelter bay 8 and one fire bay 10 may measure around 1.5m in depth, 75cm in width and 3.8m in length. If the trench is to be dug manually, the shelter bay portion 8 may be erected (in a matter of seconds) before the soldier begins to dig. It is positioned over the ground where the shelter bag is to be dug and then the soldier enters the shelter bag section 8 so that a degree of protection is provided, should there be for example enemy fire in the area.Roof panel 24, which has a ceramic cladding to deflect airborne projectiles, may be positioned against the side of the bay facing the enemy. The central frame 36 will remain in the stowed position whilst the soldier digs. As the soldier digs the trench, the shelter bay gradually falls down into the trench, thus also providing instant protection against collapse of the trench walls. As the shelter bay does not span the entire length of the trench, if it is to provide protection for the soldier at all times, the soldier must move the bay lenthwise of the trench.

When the trench is fully dug, the soldiers complete the structure as follows. An end door panel 5 is fitted at one end of the shelter bay 8, as described above. The shelter bay is then pushed into its desired position, to allow the fire bay framework to be constructed. This is acheived by the attachment of further lateral 78, vertical 80 and longitudinal 82 supports to the shelter bay using the four way clamp 43, followed by the attachment of vertical side panels 22 and a vertical end panel 28, by means of the peripheral connectors 44 and/or the door hinge connectors 70, 72 and 74, resulting in the rigid fire bay framework construction 10 shown in Fig. 8. Alternatively, the fire-bay framework 20 may be pre-assembled by a second soldier while the first soldier digs the trench, and it is then attached to the shelter bay framework in the trench.By using a variableangle joint 81 as shown in Fig. 9B and longitudinal supports of uneven length, the fire bay 10 can be attached to the shelter bay 8 at an angle if desired. As mentioned earlier, all connections are tightened by the use of a single allen key tool.

The fire bay framework 20 and panels 22, 28 extend above the top of the shelter bay 8, to ground level height 83 (Fig. 2).

The underground roof panel 16 is positioned on top of the shelter bay 12 and may be secured in place by means of suitable connectors. As shown in Figs. 2 and 3, two short lengths 84 of empty bastion blocks of the heavy quality type shown in Fig. 12 are inserted laterally in the trench on top of and at each end of the shelter bay roof 16. These are subsequently filled with soil, which conveniently be the soil dug out of the space between the bastion blocks is also filled with the diggings from the trench. This provides a strong and stable roof structure.

The fire bay above-ground roof, panel 24 is positioned on and supported by further lengths of soil-filled bastion blocks 88 at each side of the fire bay except one, which remains open to allow weapons to be fired therethrough. The structure is completed by the addition of similar lengths of bastion blocks 90 on top of the panel 24 as shown.

The fitting of a door panel 5 between the shelter bay 8 and the fire bay 10, on the fire bay side, and the fixing of floor panels to the lower longitudinal supports 32 completes the structure, of which the all-round panelling is illustrated in Figs. 5, 6 and 7.

The door panel 5 between the shelter bay 8 and the fire bay 10 provides increased protection for personnel inside the shelter bay, in that the effect of a projectile (possibly explosive) entering the fire bay through its firing aperture 92 may be deflected by the door 5.

The floor panels 18 are easily raised from one end, thus allowing storage thereunder.

As shown in Figs. 10A and 10B, each of the panels consists of 2mm aluminium alloy sheet outer cladding 94 and an injected fire-retardant polyurethane core 96, each panel being overall 40mm thick. This construction is both lightweight and highly resistant to weapon effects. Also, the panels being in contact with the frames 12 and 20 around their entire periphery, provide a means for evenly distributing loads.

The panels furthermore, being attached by connectors 44 allow the panels to twist slightly around the supports while they flex inwards in elastic response to loading.

The roof panels 16 and 24 are provided with an external layer of ceramic tiles 98, which may be held fast in place by a fibre reinforced resin coating. The tiles 98 provide increased protection against flying projectiles, which impinge upon the structure from above and might otherwise pierce an untiled panel.

The trench support system of the invention provides a system which is re-usable. Soldiers using the equipment will train to erect the system properly and in a minimum amount of time.

A further feature is that as the panels, and especially the roof panels 16 and 24, may be of an expensive nature, cheaper substitute panels may be for during training exercises to prevent accidental damage to the expensive panels.

Lifting slings 100 of the type shown in Fig. 13 may be wrapped around the shelter bay when in the flattened condition framework 12, both to aid the lowering of the framework into a trench which is pre-dug, and to enable the subsequent removal of the bay from the trench. The slings 100 are held in support guides 102 on the side panels, and the handles therof may protrude at ground level over the completed structure, to allow the structure to be conveniently removed by machine lifting without the need for further digging. Such slings could also be used to hoist the shelter bay structure 8 from the trench with an injured soldier inside.

It is also apparent that a trench structure according to the invention may collapse sideways rather than vertically. That is to say, the roof and floor panels may be permanently attached to the framework rather than side panels as described above. Frames, if used, would then fold up from the floor panels or down from the roof panels.

In a further embodiment, the flat condition of the structure may not involve collapsing, and would allow the shelter bay to be stored with one panel on top of the other. In this embodiment, the lateral supports are connected at one end and to one side panel only in the flat condition, and the subsequent erection of the shelter bay involves the further step of inserting and securing the opposite ends of the supports into clamps at the corners of the unattached side panel.

Where the depth of the trench is greater than the support system, longer vertical supports 40 and 80 may be used, and extra panel sections may be attached below the main panelling.

Any feature of the invention described herein can be used with any one or more of the other features of the invention as described herein.

It will be appreciated that the structure can be further strengthened against weapon effects by the use of further bracing in the framework and additional panelling. This is however thought to be undesirable, as it leads to a bulky structure which is not easily transportable and which takes longer to erect.

Claims (10)

1. A collapsible earth support structure for a trench, wherein the structure comprises sides for application to the sides of the trench, said sides being pivotally connected to cross bars enabling the structure to be collapsed to a flattened state in which the sides are close together, in which condition it can be transported, and an opened out state in which the sides are jacked apart by the cross bars.

2. A structure according to claim 1, wherein the structure when erected has panels at said sides.

3. A structure according to claim 1 or 2, wherein the framework additionally comprises cross frames hinged to the sides and swingable between a stored position wherein they are close to the sides and a jacking position in which they extend between the sides.

4. A structure according to claim 1, 2 or 3, wherein the framework and cross frames comprise tubes of metal which are connected to each other and/or to the panels by the use of connectors.

5. A structure according to any of claims 1 to 4, wherein the panels are attached to the exterior of the support structure so that pressure exerted on the exterior of the structure by the trench walls is transmitted directly to the framework.

6. A structure according to any preceding claim comprising a shelter bay portion and an ancillary framework to define a fire bay portion.

7. A structure according to claim 6, when used with concertina-action containers which are filled to create blocks, as described in Patent Application No. WO 90/12160, in place of conventional sandbags, such blocks providing above-ground substantial walling arrangements.

8. A structure according to any preceding claim wherein the panels comprise aluminium alloy cladding and a fire-retardant polyurethane core.

9. A structure according to claim 8, wherein said panels include roof panels provided with a further cladding of ceramic tiles to protect them against fragments of airborne projectiles.

10. An earth support structure for a trench substantially as hereinbefore described with reference tothe accompanying drawings.