GB2592950A

GB2592950A - Barrier for preventing liquid entry to an area

Info

Publication number: GB2592950A
Application number: GB2003546.5A
Authority: GB
Inventors: Toumazis Antonios
Original assignee: Individual
Current assignee: Individual
Priority date: 2020-03-11
Filing date: 2020-03-11
Publication date: 2021-09-15
Also published as: GB202003546D0

Abstract

A barrier for preventing the entry of liquid 20 into an area 10, with a buoyant body and a roll-up shutter (110 figure 1a) that has an upper end rotatably fixed relative to the buoyant body 130 and a lower end fixed relative to the ground, so that when the buoyant body is raised the shutter is unrolled. The barrier may have a guide for the shutter and the buoyant body may be in front of the shutter. The barrier may have a housing 200 below ground which may have a cover 140 over the shutter that supports traffic, and upright elements 132 to transfer traffic load to the ground. The barrier may have a structure 150 that expands vertically that resists horizontal movement when the shutter is unrolled. The vertically expandable structure may be connected to the buoyant body and be at the rear of the shutter and may be formed from a scissor lift (150 figure 5c) or telescopic shafts (152 figure 5d). The barrier may have a roll-up seal (160 figure 1d) and a prop (170 figure 4b) with a ratchet mechanism (172 figure 4b) that resists downward movement. A method of use is also claimed.

Description

Barrier for preventing liquid entry to an area The invention relates to a barrier to be disposed in front of an area for preventing the entry of liquid into said area, for example flood water or liquid spill.

The invention also relates to a method of protecting an area by using such a barrier.

Flooding is the covering by water of land not normally covered by water. Flooding is expected to be more intense and more frequent due to climate change. Living with the floods is a policy already adopted by the European Union and other states. Flood damage may be reduced by the use of flood barriers. Flood barriers should be strong enough to resist the horizontal actions such as hydrostatic pressure, current, wave and wind actions, object impact. Flood barriers should also be sufficiently watertight so that any leakage of water past the barriers is acceptable. When on stand-by flood barriers should withstand traffic action.

Flood barriers can typically be installed at a location where flooding is common and used to protect houses or other important locations.

Examples of automatic, or self-closing, or self-activating, or self-operated vertical rising flood barriers are disclosed in a number of documents. EP 2315880 Al discloses such a barrier in which, a vertical buoyant dam is forced upwards out of a chamber whenever the chamber fills up with water. The dam is normally underground and invisible to the surrounding environment.

GB 2524874 A discloses a self-activating barrier which has a low-friction surface or roller to prevent jamming. The barrier may contain secondary means for deploying the gate for example airbags and a compressor and may contain sensors for checking deployment.

Another example of a vertically rising flood barrier is shown in US 5460462, in which a vertical barrier recessed into the ground is elevated between vertical posts when water rises within a subterranean housing containing the barrier. GB2386144 B discloses a vertical rising flood barrier moving inside a trough which does not require a second chamber. The gate is buoyant and it is urged upwards by water entering the trough. The gate is held in the vertical plane by vertical posts inside the trough.

WO 00/01892 discloses a flood barrier which has a buoyant gate inside a casing and seals are provided to prevent water surrounding the lower part of the wall to pass the wall. 2 -

WO 201 5/1 20516 Al discloses another vertical buoyant gate placed inside a chamber with pivot seals to prevent leakage.

GB2374108 A discloses a roller shutter door having a flexible waterproof sheet which is normally rolled inside a roller box. This invention requires a frame fixed adjacent to the opening, the frame being made up of channels on two sides and one end whilst having the roller box on the opposite end. The flood door is activated by a float which engages an electric motor to raise the barrier. Sealing is achieved by inflating the inflatable margins of the waterproof sheet. This invention has the limitation of finite width of opening and the need for a power source to raise the barrier. The float is merely used as a method of activating the power source.

052380218 B discloses a barrier comprising a roller shutter for deployment at the opening of a building. This document discloses the use of float however this is also used to activate a power means such as compressed air.

GB2514879B by the inventor of this invention discloses a self-operated flood barrier in which a normally horizontal gate rotates to the upright position by buoyancy action from an operating member disposed below the gate and rotating in the opposite direction to the gate. Traffic may pass over the barrier by providing vertical rigid members inside the buoyant operating member. This barrier has the disadvantage that it requires horizontal space in front of the protected area longer than the height of barrier.

082549319 also by the inventor of this invention discloses a self-operated vertical rising barrier which comprises a buoyant protruding body at the crest of the flood gate, thus avoiding the need of a second chamber and the need to have a pump to empty the housing after the flood event. This barrier has the disadvantage that it requires the formation of a trench deeper than the design flood height.

For cases where an opening of large width is required to allow unobstructed passage of traffic, to provide an automatic operation of a barrier preventing the passage of liquid, the allowable depth of excavation is shallower than the flood depth, and the allowable horizontal distance in front of the opening is shorter than the flood depth then the above barriers do not fulfil all the requirements simultaneously.

Viewed from a first aspect, there is provided a barrier to be disposed in front of an area for preventing the entry of liquid into said area, comprising a roll-up shutter and a buoyant body, the roll-up shutter comprising a lower end portion which in use is to be fixed relative to ground and an upper end portion rotatably -3 -mounted relative to the buoyant body and arranged to move up or down therewith, so that in use as the buoyant body moves upwardly when liquid acts thereon the upper end portion of the roll-up shutter moves upwardly with the buoyant body and the shutter is unrolled, whereby the shutter prevents the entry of liquid into said area.

By the arrangement in which the upper end portion of the roll-up shutter is rotatably mounted relative to the buoyant body and arranged to move up or down therewith, the shutter can unroll as a result of liquid acting on the buoyant body. No electrical devices or alternative power sources are required, which would have to be carefully insulated and lead to increased installation and maintenance costs. In addition, the lower end portion of the roll-up shutter is to be fixed relative to ground, so it is easy for passage of liquid underneath the shutter at ground level to be prevented when installed.

Thus there may be provided a self-operated roll-up vertical rising barrier for protecting an area from the entry of liquid, for example flood water or liquid spill.

It will be noted that the barrier is to be disposed in front of an area for preventing the entry of liquid into said area. Thus, in this specification a forward direction is considered as the direction from the area where liquid entry is prevented (the dry or protected area) to an area where liquid accumulates when stopped by the shutter (the flooded area). A rearward direction is opposite to the forward direction. The shutter may be considered as extending laterally, transverse to the forward and rear directions.

The upper end portion of the shutter may be mounted on a roller arranged to move up or down with the buoyant body. In use, as the buoyant body moves upwardly the roller moves upwardly therewith and the shutter is unrolled from the roller.

The barrier may further comprise a guide arranged to move up or down with the buoyant body, the guide being configured to guide the shutter at a position intermediate between its lower and upper end portions during unrolling of the shutter.

It will be appreciated that the radius of the shutter in the rolled-up configuration will decrease as the buoyant body moves upwards and the shutter is unrolled. By providing a guide, this can maintain a constant position in the forward direction during rolling or unrolling. Thus the shutter may extend between its lower -4 -end portion and the guide in a substantially constant plane during rolling or unrolling. The guide may be positioned so that the shutter when unrolled extends vertically from the lower end portion to the guide.

In use, when the unrolled shutter is subject to the hydrostatic pressure of the liquid, it may be supported at its lower end portion by being fixed relative to ground and at its intermediate position by the guide, spanning in the up and down direction between the lower end portion and the guide.

The guide may be disposed forwardly of the rotatably mounted upper end portion, i.e. nearer the flooded area.

The guide may comprise a guide roller.

The buoyant body may be disposed forward of the shutter.

The shutter may comprise a plurality of hinged horizontal elements and seals located between adjacent hinged horizontal elements, and wherein in use hydrostatic pressure of the liquid acting on the shutter tends to cause compression of the seals.

The horizontal elements may be wound around the roller when in the rolled-up configuration. The hinges may all be positioned on one side of the shutter, preferably the rearward side of the shutter. By positioning the hinges on the rearward side of the shutter, hydrostatic pressure of the liquid will tend to cause adjacent edges of the horizontal elements to compress the seals and thus prevent liquid entering the area to be protected.

When the barrier is installed, the buoyant body and rolled up shutter may be located in a recess within the ground so that they are below ground level. The size of the recess in the forward direction has to be sufficient to accommodate the buoyant body and the rolled up shutter. As the recess formed in the ground is only required to contain the components of the barrier, i.e. no additional pumps, side walls or power sources, the excavation required is minimal. Thus the installation works may be limited both in the forward and rearward directions and in depth below ground level.

The barrier may further comprise a cover extending above the shutter and the buoyant body to allow traffic to be supported on the cover when the shutter is rolled up.

When no liquid is present the flood barrier will normally be at ground level. The cover may form a flush surface with the ground level to provide a smooth, level, surface for traffic to pass over. If flooding occurs, water may enter the recess in the ground surface and urge the buoyant body upwards. -5 -

The buoyant body may comprise a plurality of upright elements for transferring traffic load to ground. The space between the upright elements can be filled with a buoyant material such as polystyrene or polyurethane. The upright elements can ensure that the traffic load exerted when the barrier is in the collapsed configuration does not damage the buoyant body.

The barrier may comprise a housing for containing the shutter when rolled up and the buoyant body below ground level. The housing may be located in the recess in the ground. The housing may have the same shape and size as the recess formed in the ground.

The barrier may comprise a liquid entry portal to allow liquid to flow into contact with the buoyant body. This may be a liquid entry portal to the housing. The entry of liquid via the liquid entry portal causes initial urging of the buoyant body in the upward direction due to hydrostatic forces. There may be a grill or gully located in front of the protected area. When the barrier is installed, the housing may be connected to a drainage system. During mild rain conditions, storm water enters the housing and escapes to the drainage system without accumulation of water. In extreme events or when the drainage system is full, flood water piles up in the housing and causes the buoyant body to start to move upwardly.

One or more shutters may be positioned side by side in the lateral direction.

Each of the one or more shutters may be connected to separate buoyant bodies.

Alternatively, each of the one or more shutters may be connected to the same buoyant body. Thus a plurality of shutters can be provided to protect an area as required, depending on the lateral extent of the area.

The barrier may further comprise a vertically expandable structure comprising a first end connected to a base of the barrier, wherein the vertically expandable structure is configured to resist horizontal movement of the shutter when it is unrolled and subjected to hydrostatic pressure of the liquid.

By using a vertically expandable structure to support the shutter in this way, it is not necessary to rely on walls or the like to provide support at the lateral ends of the barrier. Thus there is no limitation to the lateral extent of the area to which entry of liquid is to be prevented.

Plural vertically expandable structures can be located at various points along the lateral extent of the barrier. This allows them to resist horizontal movement at various points along the lateral extent of the shutter.

The vertically expandable structure may comprise one or more rigid members.

The vertically expandable structure may comprise a second end connected to the buoyant body so as to move upwards with the buoyant body when liquid acts -6 -thereon. The vertically expandable structure is therefore able to expand at the same rate as the shutter unrolls.

The vertically expandable structure may be disposed to the rear of the shutter when unrolled and may extend from its first end at the base of the barrier to its second end connected to the buoyant body at a rearward spacing from the unrolled shutter.

The hydrostatic pressure of the liquid will inherently force the shutter to move in the rearward direction. Therefore, by placing the vertically expandable structure on the rear side of the shutter, this force can be effectively resisted. The vertically expandable structure may support the buoyant body, and preferably also the roller and the guide, against rearward movement when the buoyant body is located upwardly, away from the ground.

In use, it is preferable that there is no contact between the shutter and the vertically expandable structure. Thus, in embodiments, the unrolled shutter may extend from its lower end portion to the guide, and the vertically expandable structure may be at a rearward spacing from the unrolled shutter. The shutter may be prevented from bending significantly by providing the hinges on the rearward side of the shutter. Furthermore, the thickness of each horizontal element of the shutter, in conjunction with the seals between horizontal elements may prevent further bending of the shutter.

The vertically expandable member may comprise a scissor lift. The scissor lift may comprise two sections that are spaced apart in the forward direction. Each section of the scissor lift may be connected by one or more forwardly extending members. The scissor lift may comprise a plurality of rigid members which are hinged together and allowed to collapse and expand in the vertical direction.

At a first end of the scissor lift, one of the rigid members may be fixed in the lateral direction to the base of the barrier. A second rigid member at the first end may be free to move in the lateral direction along the base. Similarly, at a second end of the scissor lift, one of the rigid members may be fixed in the lateral direction to the buoyant body. A second rigid member at the second end may be free to move in the lateral direction along the underside of the buoyant body. The rigid members may be pivotally mounted such that they are allowed to pivot in a vertical plane. This arrangement allows the scissor lift to expand as the buoyant body is urged upwards due to hydrostatic pressure.

The barrier may comprise multiple scissor lifts. Each scissor lift may have the same width in the lateral direction. Alternatively, each scissor lift may differ in width in the lateral direction.

Alternatively, or in addition to the scissor lift, the vertically expandable structure may comprise one or more telescopic shafts. Each shaft may be -7 -connected to the base of the barrier at a first end and the buoyant body at a second end.

Each telescopic shaft may be regularly spaced along the lateral length of the barrier to provide support to the shutter against horizontal movement under hydrostatic pressure. Each telescopic shaft may comprise two or more shaft sections located within each other. Each corresponding section of each telescopic shaft may be equal in diameter.

The vertically expandable structure preferably sufficiently supports the barrier so that no side walls or additional vertical posts are required to support the barrier. This further reduces the size and excavation requirements of the barrier.

The vertically expandable structure can be made of any suitable material. For example, it may be made of metal such as steel or aluminium.

The barrier may further comprise a roll-up seal located at a lateral end of the shutter.

The roll-up seal may comprise a first end which in use is to be fixed relative to ground, and a second end fixed to a seal supporting roller, wherein the seal supporting roller is arranged to move with the buoyant body so that in use as the buoyant body moves upwardly the roller moves upwardly therewith and the seal is unrolled.

In use the hydrostatic pressure acting on the shutter may tend to cause compression of the roll-up seal. This can be achieved by the roll-up seal being located forwardly of the shutter. The seal supporting roller may also be located forwardly of the shutter.

The roll-up seal may be used to seal the space between a shutter and a wall or the like at the lateral end of the shutter. Alternatively, or additionally, the roll-up seal can be used to seal the space between two adjacent shutters.

The roll-up seals mean that each lateral end of the shutter will be effectively sealed to walls or the like which the barrier is extended between. No additional features are required to attach the barrier to the walls or the like. In embodiments, the barrier is supported by the vertically expandable structure and sealed by the roll-up seal at each lateral end of the shutter under the force caused by the hydrostatic pressure.

The barrier may further comprise a prop configured to engage with one of a plurality of protrusions.

The prop may have a first end pivotally mounted so as to move upwardly with the buoyant body, and a second end configured to engage with a respective protrusion dependent on the height to which the buoyant body moves upwardly. The prop and the plurality of protrusions may form a ratchet mechanism. -8 -

The prop may be configured to allow the buoyant body to move in an upward direction when liquid acts thereon but to resist movement in a downward direction.

The hydrostatic pressure is intended to support the buoyant body in the vertical direction, but the prop can provide additional vertical support. The prop can be configured so that as the buoyant body moves upwards, the second end of the prop is angled so that it passes over the plurality of protrusions. Once the buoyant body has reached a given height, the angle of the prop means that it engages with one of the plurality of protrusions and cannot move in the opposite direction.

Eventually the liquid level will reduce and the hydrostatic pressure will no longer urge the buoyant body in the upward direction. At this point the prop can provide the vertical support and maintain the barrier in the raised position by engaging with one of the plurality of the protrusions.

This allows for any debris that may have accumulated in and around the shutter to be cleared. The shutter and the seals can also be cleaned. The prop can be released from the protrusion with which it is engaged, and the shutter can then be rolled up. This can be done for example by manually winding the plurality of horizontal elements of the shutter around the roller as the buoyant body is manually lowered.

According to a second aspect, there is provided a method of protecting an area by using the barrier as set out in the first aspect.

According to a third aspect, there is provided a barrier, as set out in the first aspect, disposed in front of an area for preventing the entry of liquid into said area. Certain embodiments of the invention will now be described, by way of example only, and with reference to the accompanying drawings, in which: Figs. 1-5 show an exemplary embodiment of a barrier preventing the entrance of liquid into a protected area for example a barrier protecting the entry of flood water or spill to through a step free opening; Figs. la and lb show the exemplary embodiment in vertical cross section through the middle of the barrier, in normal position and in raised position and Figs. lc and ld show the same arrangement but with the section at the edge of the barrier; Fig. 2a shows the same exemplary embodiment in axonornetric sectional view at a raised position as seen from the front side without illustrating the edge seals and Fig. 2b shows the same arrangement with the edge seals; Fig. 3a shows the same exemplary embodiment but from the rear side without the prop and fig. 3b shows a detail of the shutter and hinges; -9 -Fig. 4a shows the same arrangement as fig. 3a but without the restraining vertically expandable structure and instead it shows the prop for preventing downward movement, and Fig. 4b shows a detail of the one way restraint of the prop bottom end; and Figs. 5a, 5b and 5c show the same embodiment in plan, front elevation and rear elevation when the barrier is in elevated position, and Fig. 5d shows an alternative embodiment of the restraining vertically expandable structure. In this embodiment the restraint is provided by retractable columns, the bottom columns embedded in the ground below the barrier.

The drawings, details and descriptions of the embodiments are non-limiting ways in which the concepts of the invention may be applied. Their aim is to illustrate to skilled persons the use of the present invention in any appropriate system, method, apparatus or construction.

Reference in this document to "an embodiment" means that a particular feature, structure, or characteristic is included in at least one embodiment and it does not necessarily refer to the same embodiment. Particular features, structures, or characteristics may be combined in one or more embodiments. Variations may be made within the scope of the invention and parts shown in the drawings or described may be implemented in a more separated or integrated manner, or removed or rendered as inoperable. Numerous alternative and different embodiments may be made using concepts of this invention. Drawings, details and descriptions are interpreted as illustrative and not as limiting the invention.

The figures are illustration examples of embodiments of the invention. The figures are not to scale. Like or similar parts are marked on the figures and referred in the descriptions with the same numbers. Groups of parts are referred as a whole with numbers and are marked in the figures with arrowheads.

For the sake of clarity some parts in the figures are shown exaggerated, smaller or schematically, some are omitted and some details are not shown. In the exemplary embodiment illustrated in figures 1 to 5, the barrier is disposed in front of an area 10, so that the barrier protects area 10 from the entry of liquid 20. A roll-up shutter 110 is comprised of a plurality of horizontal elements 112 pivoted to each other by means of hinges 114 so that when the shutter is unrolled and pressed from the opposite side of said hinges 114 said horizontal elements 112 form a planar rigid impermeable curtain. Said horizontal elements 112 may for example be aluminium or stainless steel rectangular hollow sections.

-10 -The one end of said shutter 110 is affixed to a pivot axis in the form of a roller 122 disposed inside a rigid roller box 120 housing the shutter when said shutter 110 is rolled. The other end of said shutter 110 is affixed to partition element 230, said shutter 110 rolling around pivot 124, said pivot 124 being affixed to said roller box 120.

A buoyant body 130 is affixed to the front of said roller box 120 so that when in normal position said buoyant body 130 is below ground level and when wetted by liquid 20 said buoyant body 130 urges said roller box 120 to move upwardly. Said buoyant body 130 comprises a plurality of upright columns 132 and the voids within said body 130 are filled with light weight material 134 such as polystyrene or polyurethane.

A vertically expandable structure 150 which provides horizontal restraint is affixed to the lower side of said upper portion 120 so that when hydrostatic action urges said shutter 110 to move towards the rear side said structure 150 prevents the barrier from sliding and or overturning.

In normal use the above components are hidden below grade housed inside a rigid housing 200. The lower edge of said shutter 110 is affixed to the partition element 230, said element 230 separating the forward housing 210 from the rear housing 230. Said buoyant body 130 is normally resting inside forward housing 210 and said structure 150 is affixed to said rear housing 220.

During normal use, top surface 140 is flush with the ground level, said surface 140 being affixed to both roller box 120 and buoyant body 130. Said top surface 140 transfers traffic load to rear step 222 and to said upright columns 132.

On liquid pile up inside forward housing 210, buoyant body 130 urges said roller box 120 upwardly. As said roller box 120 moves upwardly shutter 110 unrolls and hydrostatic pressure urges said horizontal elements 112 towards the rear. Hinges 114 restrain said elements 112 thereby a planar rigid curtain is formed preventing the passage of liquid 20 to protected area 10. Seals 166 affixed to the sides in between horizontal elements 112 may for example close any gaps that may exist in between said horizontal elements 112.

The resistance to horizontal movement is provided by said structure 150.

Said horizontal restraint may for example be a scissor lift 150 or a plurality of telescopic shafts 152.

The barrier further comprises a roll up seal 160 closing the gap at the edges of said shutter 110. Said edge seal 160 is rolled around pivot axis 162, said pivot axis in the form of a roller 162 being affixed on the side of said buoyant body 130. The other end of said seal 160 is affixed to said partition element 230. Said seal 160 rolls around pivot 164, said pivot 164 being affixed to said buoyant body 130 adjacent to said shutter 110.

The barrier comprises a prop 170 for preventing the barrier from moving downwards when the hydrostatic pressure decreases. Said prop 170 is pivoted below top surface 140 and in normal position said prop 170 rests on rear step 222. The upper surface of said step 222 is configured so that it has a ratchet shape 172 allowing said prop 170 to slide as barrier rises but preventing sliding as liquid level comes lower.

It will be seen that there is disclosed herein an upward rising barrier which is automatically self-closing. The barrier is for preventing the passage of flood water, chemical spills or other liquids from one area to an adjacent one. A barrier is provided between the two areas so that the barrier top surface rests flush with grade level.

At least in the preferred embodiment of the invention the following advantages are obtained: 1. The barrier is self-operated requiring no power or human intervention; 2. The barrier is normally flat with grade, requiring no threshold, no frames or vertical posts; 3. The barrier is self-supported, having resistance to both vertical and horizontal actions, being able to protect openings of wide widths; 4. The barrier top surface may accommodate heavy traffic load. 25

Claims

-12 -CLAIMS1. A barrier to be disposed in front of an area for preventing the entry of liquid into said area, comprising a roll-up shutter and a buoyant body, the roll-up shutter comprising a lower end portion which in use is to be fixed relative to ground and an upper end portion rotatably mounted relative to the buoyant body and arranged to move up or down therewith, so that in use as the buoyant body moves upwardly when liquid acts thereon the upper end portion of the roll-up shutter moves upwardly with the buoyant body and the shutter is unrolled, whereby the shutter prevents the entry of liquid into said area.
2. A barrier as claimed in claim 1, wherein the upper end portion is mounted on a roller.
3. A barrier as claimed in claim 1 or 2, comprising a guide arranged to move up or down with the buoyant body, the guide being configured to guide the shutter at a position intermediate between its lower and upper end portions during unrolling of the shutter.
4. A barrier as claimed in claim 1, 2 or 3, wherein the buoyant body is disposed forward of the shutter.
5. A barrier as claimed in any preceding claim, wherein the shutter comprises a plurality of hinged horizontal elements and seals located between adjacent hinged horizontal elements, and wherein in use hydrostatic pressure of the liquid acting on the shutter tends to cause compression of the seals.
6. A barrier as claimed in any preceding claim, comprising a cover extending above the shutter and the buoyant body to allow traffic to be supported on the cover when the shutter is rolled up.
7. A barrier as claimed in claim 6, wherein the buoyant body comprises a plurality of upright elements for transferring traffic load to ground.
8. A barrier as claimed in any preceding claim, comprising a housing for containing the shutter when rolled up and the buoyant body below ground level.
9. A barrier as claimed in any preceding claim, comprising a liquid entry portal to allow liquid to flow into contact with the buoyant body.
10. A barrier as claimed in any preceding claim, further comprising a vertically expandable structure comprising a first end connected to a base of the barrier, wherein the vertically expandable structure is configured to resist horizontal movement of the shutter when it is unrolled and subjected to hydrostatic pressure of the liquid.
11. A barrier as claimed in claim 10, wherein the vertically expandable structure comprises one or more rigid members.
12. A barrier as claimed in claim 10 or 11, wherein the vertically expandable structure comprises a second end connected to the buoyant body so as to move upwards with the buoyant body when liquid acts thereon.
13. A barrier as claimed in claim 12, wherein the vertically expandable structure is disposed to the rear of the shutter when unrolled and extends from its first end at the base of the barrier to its second end connected to the buoyant body at a rearward spacing from the unrolled shutter.
14. A barrier as claimed in any of claims 10 to 13, wherein the vertically expandable structure comprises a scissor lift.
15. A barrier claimed in any of claims 10 to 14, wherein the vertically expandable structure comprises one or more telescopic shafts.
16. A barrier as claimed in any preceding claim, further comprising a roll-up seal located at a lateral end of the shutter.
17. A barrier as claimed in claim 16, wherein the roll-up seal comprises a first end which in use is to be fixed relative to ground, and a second end fixed to a seal supporting roller, wherein the seal supporting roller is arranged to move with the buoyant body so that in use as the buoyant body moves upwardly the roller moves upwardly therewith and the seal is unrolled.
18. A barrier as claimed in claim 16 or 17, wherein in use hydrostatic pressure acting on the shutter tends to cause compression of the roll-up seal.
19. A barrier as claimed in any preceding claim, further comprising a prop configured to engage with one of a plurality of protrusions.
20. A barrier as claimed in claim 19, wherein the prop has a first end pivotally mounted so as to move upwardly with the buoyant body, and a second end configured to engage with a respective protrusion dependent on the height to which the buoyant body moves upwardly.
21. A barrier as claimed in claim 19 or 20, wherein the prop and the plurality of protrusions form a ratchet mechanism.
22. A barrier as claimed in claim 19, 20 or 21, wherein the prop is configured to allow the buoyant body to move in an upward direction when liquid acts thereon but to resist movement in a downward direction.
23. A method of protecting an area by using a barrier as claimed in any preceding claim.
24. A barrier as claimed in any of claims 1 to 22, disposed in front of an area for preventing the entry of liquid into said area.