GB2081766A - Blastproof shelter - Google Patents

Abstract

An underground shelter consists of an airtight tubular or spherical shell divided into two compartments 11, 12. Each compartment is accessible from the other compartment, and each can be entered from outside the shell via its own hatch. One has two successive covers 21, 22, the outer of which can only be opened from the main living compartment of the shell, the other compartment serving as an entry and decontamination compartment. <IMAGE>

Description

SPECIFICATION Blastproot shelter The invention relates to blastproof shelters.

The'invention is particularly applicable to shelters which are intended to be located underground and whose primary purpose is to protect their occupants from the effects of a nuclear blast and the subsequent fallout.

Known forms of shelter intended for this purpose are made of thick concrete blocks or panels: they are heavy, expensive, they have to be assembled and installed on site rather than being able to be assembled under controlled conditions in a factory, and they are not wholly waterproof.

The invention seeks to provide a shelter which will provide protection to its occupants whilst at least reducing the drawbacks listed above.

The inventive concept springs from the realisation that a satisfactory blastproof shelter can be constructed in the form of a sealed curvedsurface pressure vessel. The criteria governing the design of such vessels are well known and have been precisely evaluated: they can thus be applied with precision to the construction of a blastproof shelter, and the resulting shelter will exhibit optimum efficiency of construction and performance. The shelter can be manufactured under closely controlled conditions, in a factory specially equipped for the purpose and well removed from the eventual site of installation. A shelter based on the design of a steel pressure vessel is considerably lighter than the known concrete shelters, and can thus be transported easily from factory to site. It can also be more easily installed.Given the current advanced state of the art of forming sealed-shell pressure vessels, the shelter can be more easily rendered airtight and waterproof than can the concrete shelters of known design. There is also far greater scope for internal fitting out of such steel shelters, since it is far easier to weld and bolt fitments onto the internal shell of a steel vessel, once inside the shell, than it is to attempt similar operations on the inside walls of a concrete block or panel structure.

The inventive concept envisages a shelter which is basically in the form of an airtight tubular or spherical shell internally divided into two compartments each of which is accessible from the other; each of which can be entered from outside the shell via its own hatch; each hatch incorporating means to lock it shut from beneath; at least one hatch being reopenable only from beneath; and a filtration system which can be operated from within the shell and can be completely closed off from within the shell, to allow air in the main living compartment to be changed at a controllable rate; the whole construction being such that when the hatch covers and the filtering system are closed, the shell is substantially airtight.

In its broadest aspect the invention provides a shelter, primarily intended for use as an underground shelter to protect its occupants against the effects of a nuclear blast and the subsequent fallout, the shelter comprising a curved-surface steel sheel (for example an elongate tube closed at each of its ends, or a closed sphere) divided internally into two compartments by a partition which is normally closed to form a sealed dustproof division between the compartments but which (or part of which) can be opened to allow occupants to pass from one compartment to another; separate hatches affording respective means of access to each compartment from outside the shell and enabling respective occupants of either compartment to leave the shell from within that compartment without first having to pass through said partition (or part thereof) into the other compartment; each hatch having its own selectively openable and closeable external cover; each hatch incorporating means to lock it shut from beneath; at least one hatch being reopenable only from beneath; and means, operable from within the shell to expel air from the compartment accessible via said further cover and to draw air into that compartment, in each mode at a controllable rate and, at least in the last mentioned mode, via a filtering means which can be selectively opened and closed from within the shell; the construction being such that when the hatch covers and the filtering means are closed, the shell is substantially airtight.

Where the shell takes the general form of an elongate tube closed at each of its ends, the end closure caps may be in the form of ellipsoids since this form will most readily withstand the external pressures to which the shell, in use, is subjected.

Preferably the external hatch covers are in the form of ellipsoids, since these hatch covers, in use may be at ground level when the shell is submerged beneath the ground; and the hatch covers will then most readily withstand the external pressures to which they are subjected.

Two shelters each embodying the invention are shown, by way of example only, in the accompanying drawings. Each shelter will now be described with reference to those drawings, in which: Figure 1 is a cutaway perspective view showing the first shelter; and Figure 2 is a similarly cutaway perspective view showing the second shelter.

Referring initially to figure 1, the shelter shown therein consists essentially of an elongate cylindrical pressure vessel closed at each of its opposite ends by respective ellipsoidal caps. The entire tubular vessel is formed from sheet steel approximately 10 mm thick: it could be rolled and then seam-welded, or the main tube could instead be formed as a seamless tube and then subsequently capped and welded around the juncture of the tube ends with the respective caps.

The precise way in which the basic tubular closed vessel is formed is a skilled art, well known to pressure vessel designers, and the precision to which the art has advanced is a major contributory factor towards the design and constructional efficiency of shelters embodying the invention.

The basic tubular vessel shown in figure 1 is approximately 4 metres long from end cap to end cap, and nominally 2 metres in diameter. As shown, it is reinforced by external steel bands which are spaced apart along the vessel from one another and which, in each case, extend wholly around the external circumference of the vessel.

Such reinforcing bands may take one of several known cross sections and are usually stitch welded in place. They are not to be taken as being essential features of the invention.

The vessel is divided internally into two adjacent compartments, given the respective reference numerals 11 and 12. The first compartment 11 serves, as will shortly be explained, as an entry and decontamination compartment: the second compartment 1 2 is considerably larger than the first compartment, and is the main living compartment of the shelter.

The compartments are defined and separated from one another by a circular cylindrical sheet steel partition 13 which is welded around the internal circumference of the vessel to form a substantially dustproof seal between the two compartments 11, 12.

The partition 13 is a flat plate and is approximately 6 mm thick. A square opening, large enough for a man of average size to crawl through, is cut out of one region of the partition 13. A cover 14 is hinged to the partition 13 so as to overlie this opening. The cover 14 can be selectively opened and closed: when opened, it allows occupants of the shelter to go from the compartment 11 to the compartment 12 and vice versa, and when closed it forms a substantially dustproof seal over the opening in the partition 13.

Two sections of rectangular floor plate, referenced respectively 15, 16, are stitch-welded along one internal wall of the vessel. These plates 15, 16 act as floor plates in use. They define the way in which the vessel will be orientated when it is eventually submerged beneath the ground. They are shown as solid sheet steel plates, but they could take the form of a perforated mesh.

Because the partition 1 3 is welded wholly around the internal surface of the vessel, to give a substantially dustproof seal, separate sections 1 5, 16 of plate are provided and are welded to the internal wall of the vessel and to each respective face of the partition 13.

A steel circular cylindrical hatch 1 7 projects from the external surface of the vessel towards one end of the vessel. A second hatch 1 8, also circular cylindrical, projects from the external surface of the vessel towards the other end of the vessel. Both hatches project in the same direction, generally away from the floor 1 5, 1 6 of the vessel.

Openings (not referenced) are cut into the walls of the vessel so that the hatches afford a means of access into, respectively, the compartments 11 and 12.

Each hatch has its own hinged cover, referenced respectively 19, 21. Both these covers are ellipsoids, that is to say, they are dished in a direction outwardly from the interior of the vessel.

Each cover, when closed, forms a substantially airtight seal around the top of its corresponding hatch. Both covers can be locked shut from beneath. When so locked, they cannot be reopened from above until the locks are released from beneath. Hatch 1 8 incorporates a further cover 22. This further cover is again hinged to the hatch, but is in the form of a flat circular steel plate. It is mounted inside the hatch, approximately in the plane of the surface of the vessel. The hatch covers 21,22 are each approximately half as thick in cross section as the material of cover 19.

An interlock, not shown in any detail but referenced generally 23, prevents the hatch cover 21 from being opened unless the cover 22 has first been closed. The same interlock prevents the cover 22 from being opened unless the cover 21 has first been closed. This interlock is optional.

The outer cover 21 can only be opened from beneath (i.e. from within space 12). The optional interlock may be wholly mechanical or it can take any one of a number of other forms such d5 electro-mechanical or pneumatic interlocks. It need not be described in detail, since the precise features of its design can be left to the man skilled in the art.

An air inlet pipe 24 projects through the surface of the vessel and into the main living compartment 12 towards one end thereof. An air outlet pipe 25 projects similarly into the main living compartment 12 but towards the other end thereof. The inlet pipe 24 reaches almost down to the floor 16; the outlet pipe 25 projects only a few centimetres into the compartment 12. Both pipes project away from the vessel in the same general direction as the hatches 17, 1 8, but the pipes 24, 25 reach slightly higher than the tops of the hatch covers 19,21.

Although each pipe 24, 25 is normally fully open for ventilation, end caps (not shown) are screwed to the lower end of each pipe and enable the pipes to be sealed in a substantially airtight manner from within the compartment 12.

A further pipe 26 also projects from the main compartment 12 and reaches through approximately the same height as the two pipes 24, 25. This further pipe 26 is the combined intake and outlet for a hand operated filter system referenced generally 27 by means of which the occupants of the compartment 12 can, at a controllable rate, draw air into that compartment from outside the shell and expel air from the compartment. The filter system 27 is described in brief detail later on: it can be used alone, or in conjunction with the ventilation pipes 24, 25, to change the air in the compartment 12. The pipes 24, 25 would of course normally incorporate filters of their own, and the filter system 26, 27 can, like these pipes 24, 25, be completely sealed off in an airtight manner by the occupants of the compartment 12 should they desire to do so.

The two hatch covers 19,21, achieve airtight seals by using a sealing gasket of soft asbestos rope impregnated with wax. The covers 1 4, 22 seal by this same method. The hatches 1 7, 1 8 are each approximately 0.6 metres tall and approximately 0.75 metres in diameter. The covers 14, 22 form dustproof, not airtight, seals.

A steel step ladder 28 is stitch-welded down one face of the partition 13, so that persons entering via the hatch 1 7 can more easily reach the floor plate 1 5 of the decontamination compartment 11.

Lugs 29, 31, 32 are welded at a distance below each of the respective covers 1 9, 22, 21. A small hydraulic ram, incorporating its own hydraulic pump, is referenced generally 33 and is provided as part of the shelter. One end of the unit 33 can be detachably secured to any of the lugs 29, 31, 32: the other end can bear against the respective hatch cover 19, 22, 21. When the hand pump is operated to extend the ram, the appropriate hatch cover can be opened, thus saving the extreme physical effort of lifting the relatively heavy steel covers by hand.

In use, the shelter in the form described thus far is transported to site; elongate steel channels respectively 34, 35 are welded, on site, so as to project laterally of the vessel as shown; the assembly is then lowered into a previously excavated pit; lengths of steel mesh (referenced 36) are spot-welded so as to span each of the channels 34, 35 and extend longitudinally along either side of the vessel; and a layer 37 of concrete is poured around each steel mesh and is allowed to set. Further concrete, not shown, can if desired be poured around the vessel itself, followed by earth until the vessel is fully embedded and submerged beneath the ground with the covers 1 9, 21 approximately at ground level.

The channels 34, 35, the grids 36 and the concrete 37 prevent the shelter from inadvertently being displaced in areas where the ground frequently becomes waterlogged.

The interior of the vessel is largely unfitted, since the occupants will want to choose the articles they take with them and will also want the minimum of obstruction inside the vessel. Lighting means, beds, chemical toilet facilities etcetera are left to the choice of the occupants. the interior of the vessel would be finished for example in a light green paint so that any lighting brought by the occupants would be reflected to maximum advantage without the interior surfaces appearing too stark. The exterior surfaces, including the hatches and the air filter pipes, are coated with a bituminous coating to render them waterproof.

The shelter shown in figure 2 is similar in construction to that of figure 1. The same reference numbers have therefore been allocated to corresponding features in each of the two figures. The main difference between the structure of figure 2, and that of figure 1, is that the figure 2 structure takes the general form of a closed steel sphere.

Although parts such as the interlock 23, and the mesh plates 36, are not shown in figure 2, they are nevertheless present. The pipes 24, 25, 26 have in figure 2 been combined into a single pipe; and there are two channels 34, 35 instead of the four channels of the structure of figure 1. The lugs 29, 31, 32 are also appropriately positioned on the figure 2 structure although they are not specifically referenced in the figure.

The filtering system 27 referred to previously consists basically of a hand operated rotary impeller which, when rotated, draws air down the pipe 26 and through a sealed filtering box from whence it is expelled into the compartment 12.

To expel air (or to take in fresh air when there is no danger of the air being contaminated) the filter box can be uncoupled so that the fan draws air down the pipe and directly through its impeller before expelling it into the compartment 12. The unit containing the fan and filter box is portable, and its intake can be uncoupled from the lower end of the pipe 26 and can be selectively coupled to either of the pipes 24 and 25 instead of the pipe 26.

A suitable unit is made by the firm of Andair Limited of Thurtalstrasse, Ch 8450 Andelfingen, Switzerland, and is known as the type Va 20.

The unit 27 illustrated in figures 1 and 2 can be made to expel air from the compartment 12 by connecting the units to the lower end of the air outlet pipe 25 and rotating the fan in the opposite direction to that which causes air to be drawn in through the unit.

The locks for the external covers 19, 21 need not be described in detail. They are mounted on the underside of each cover: they do not pierce the cover.

The hatch 1 7 could be provided with a second cover, similar to the cover 22, to serve as a radiation shield (as the cover 22 does). Any such radiation cover (including the cover 22) must be sufficiently thick to satisfy current regulations.

Claims (18)

1. An underground shelter comprising a curvedsurface closed steel shell divided internally into two compartments by a partition which is normally closed to form a sealed dustproof division between the compartments but which (or part of which) can be opened to allow occupants of the shelter to pass from one compartment to another; separate hatches affording respective means of access to each compartment from outside the shell and enabling respective occupants of either compartment to leave the shell from within that compartment without first having to pass through said partition (or part thereof) into the other compartment; each hatch having its own selectively openable and closeable external cover; each hatch incorporating means to lock it shut from beneath; at least one hatch being reopenable only from beneath; and means, operable from within the shell, to expel air from the compartment accessible via said one hatch and to draw air into that compartment, in each mode at a controllable rate, and, at least in the last-mentioned mode, via a filtering means which can be selectively opened and closed from within the shell; the construction being such that when the hatch covers and the filtering means are closed, the shell is substantially airtight.

2. A shelter according to Claim 1, in which the external hatch covers are generally ellipsoidal in form.

3. A shelter according to Claim 1 or Claim 2, in which the curved-surface closed steel shell comprises an elongate tube closed at each of its ends, and the end closure caps of the tube are generally ellipsoidal in form.

4. A shelter according to Claim 3, in which said partition runs generally across the axis of the elongate tubular shell and divides the shell into two longitudinally accessible compartments.

5. A shelter according to any of Claims 1 to 4, in which said compartment accessible via said one hatch is substantially larger than the other compartment.

6. A shelter according to any of Claims 1 to 5, in which a single means draws air into said compartment and expels air therefrom.

7. A shelter according to any of Claims 1 to 6, in which the air-indrawing and/or air-expelling means comprises a hand-operable rotary fan.

8. A shelter according to any of Claims 1 to 7, in which at least one hatch projects from the outer surface of the shell.

9. A shelter according to Claim 8, in which both hatches project generally upward from the outer surface of the shell when the shelter, in use, is installed in its normal position for occupancy.

10. A shelter according to any of Claims 1 to 9, in which at least one hatch has a further openable and closeable cover between its external cover and its compartment.

11. A shelter according to any of Claims 1 to 10, in which reinforcing bands external at least part-way round the external surface of the shell.

12. A shelter according to any of Claims 1 to 11, in which a part of said portion between the compartments can be opened to allow occupants to pass from one compartment to another, and said part comprises a hinged door in the partition

13. A shelter according to any of Claims 1 to 12, in which the compartment other than said compartment accessible via said one hatch affords a decontamination chamber when the shelter is used as a nuclear fallout shelter.

14. A shelter according to any of Claims 1 to 13, in which the air-indrawing and/or air-expelling means incorporates a gas filter.

15. A shelter according to any of Claims 1 to 14, in which a one-way valve is incorporated into the air-expelling means.

16. A shelter according to any of Claims 1 to 15, in which a ladder hangs substantially vertically from the hatch into the compartment other than said compartment accessible via said one hatch.

1 7. A shelter substantially as described herein with reference to, and as illustrated in, Figure 1 of the accompanying drawings.

18. A shelter substantially as described herein with reference to, and as illustrated in, Figure 2 of the accompanying drawings.