WO2007099358A1

WO2007099358A1 - Barrier apparatus

Info

Publication number: WO2007099358A1
Application number: PCT/GB2007/000758
Authority: WO
Inventors: Fiona Meikle
Original assignee: Meiklewall Scotland Limited
Priority date: 2006-03-03
Filing date: 2007-03-05
Publication date: 2007-09-07
Also published as: GB2435664B; GB2435664A; GB0604257D0

Abstract

A barrier apparatus comprising one or more barriers, the or each barrier comprising: a trough section; and a wall section movable between a first position in which the wall section is substantially contained within the trough section and a second position in which the wall section extends substantially vertically from the trough section, wherein the wall section includes: a barrier membrane, wherein at least one portion of the barrier membrane is flexible such that the wall section is in a collapsed state when the wall section is at the first position; and a plurality of first beam members for laterally supporting the barrier membrane when the wall section is at the second position, wherein the first beam members are vertically spaced apart when the wall section is at the second position.

Description

Barrier Apparatus

The present invention relates to barriers. In particular, but not exclusively, the invention relates to flood prevention barriers and impact resistant barriers which can be selectively raised or lowered.

It is known to provide flood walls adjacent to water courses, such as rivers or streams, where there is a risk of an increase in water level following heavy rainfall. Such flood walls often take the form of in situ concrete walls or earthwork structures such as bunds. However, permanent walls can be visually obtrusive when the water course is at its normal level.

It is also known to provide flood walls which rise as the level of water in the water course increases. For instance, PCT/GB99/02116 discloses a flood prevention barrier which includes a number of rigid floating flood walls, each contained within a trough. The depth of the trough corresponds to the height of each flood wall. The trough communicates with the water course so that the trough fills with water as the level of the water course rises beyond a predetermined level, thereby causing the floating flood wall to rise and preventing the rising water from flowing beyond the flood prevention barrier apparatus into the surrounding area. However, such barriers typically require a deep trough section for the wall when it is lowered. This adds to the complexity and cost of installing the barrier.

It is typical in the prior art for the flood wall to provide both the barrier surface for containing flood water and the structural resistance to the significant lateral loads imparted by the flood water.

According to a first aspect of the present invention, there is provided a barrier apparatus comprising one or more barriers, the or each barrier comprising: a trough section; and a wall section movable between a first position in which the wall section is substantially contained within the trough section and a second position in which the wall section extends substantially vertically from the trough section, wherein the wall section includes: a barrier membrane, wherein at least one portion of the barrier membrane is flexible such that the wall section is in a collapsed state when the wall section is at the first position; and a plurality of first beam members for laterally supporting the barrier membrane when the wall section is at the second position, wherein the first beam members are vertically spaced apart when the wall section is at the second position.

The term "collapsed" is intended to cover wall sections having a barrier surface which is folded or rolled or telescopically retracted when the wall section is at the first position. The term "membrane" is not intended to imply any limitations on thickness. The barrier apparatus may be a flood prevention barrier apparatus. At least a portion of the wall section may be buoyant such that, as the water level in the trough rises beyond a predetermined level, the wall section rises under the action of buoyancy with the water level in the trough section.

The barrier apparatus may provide a barrier against other hazards such as fire, landslide, avalanche or the like. Actuation means may be provided to move the wall section between the first position and the second position. The actuation means may be mechanical, hydraulic or electrical or a combination. The actuation means may be manually operable. Alternatively or in addition, the barrier apparatus may include one or more sensors. The actuation means may be operable in response to the signal from the or each sensor.

The barrier apparatus may be substantially linear. Alternatively, the barrier apparatus may form a continuous boundary so as to provide a container for substances within the boundary when the wall section is at the second position. The substances may be solid, liquid or gas. The substances may be hazardous.

The barrier apparatus may provide protection from invasion or attack. The apparatus may be intended to repel terrorist attacks. The barrier membrane may be formed from a material which is resistant to attacks or impacts, such as a bullet-proof material. The barrier membrane may be formed from a Kevlar material.

Alternatively, the apparatus may be located at homes or business premises to prevent intruders from entering these buildings. Preferably the barrier apparatus includes a support member adapted to support the extended wall section. Preferably the support member is provided at the trough section. Preferably the support member comprises one or more rigid columns.

Preferably the support member is vertically extendible from the trough section. Preferably the trough section includes one or more bores extending into the ground from the base of the trough section and at least a portion of the support member is provided within the or each bore when the wall section is at the first position.

Preferably the support member comprises one or more cylindrical shafts. Preferably a sleeve is provided in the or each bore and the or each shaft is slideable relative to the or each sleeve. Preferably the outer diameter of the or each shaft is less than the internal diameter of the or each sleeve such that an annulus is defined. Preferably one or more guide members are provided at the annulus.

Alternatively, the support member comprises one or more fixed columns which extend vertically from the trough section and the wall section is movably supported by the support member.

Preferably the wall section is provided within an insert or cassette which is insertable into the trough section. Preferably the insert has a width which substantially corresponds to the width of the trough section. Preferably the insert has a length which substantially corresponds to the distance between two columns. The provision of the insert simplifies transportation and installation. Preferably at least a portion of the support member is buoyant. Preferably the support member is coupled to the wall section and moves with the wall section as it moves from the first position to the second position. Preferably the support member comprises one or more hollow cylindrical shafts which are closed at at least the lower end. Preferably water is free to enter the bore annulus and then act upon the closed end of the or each shaft.

Preferably one or more channels are provided at the base of the trough section for dissipating water entering the trough section. Preferably the or each channel is in fluid communication with a drainage member provided exterior to the trough section.

Preferably the plurality of first beam members are substantially horizontal. Preferably each of the first beam members is structurally coupled to the support member. Preferably each of the first beam members is slidably coupled to the support member. Preferably each of the first beam members is buoyant.

Preferably the wall section comprises a sheet material to provide the barrier membrane. Preferably the barrier membrane is formed from a polyethylene or polyvinylchloride material. Preferably the barrier membrane is formed from a material which inhibits biological growth on the surface of the barrier membrane. Preferably the barrier membrane is formed from a material such as lko Spectraplan™.

In a first embodiment of the invention, preferably the membrane is fixed at a fixing location to each of the plurality of first beam members. Preferably the lower end of the membrane is sealably fixed at the base of the trough section. Preferably the distance between the fixing locations defines the vertical spacing of the first beam members when the wall section is at the second position.

Preferably each of the first beam members comprises a plate member which, in use, is substantially horizontal. Preferably each plate member includes an aperture at each end for receiving the columns of the support member.

Preferably the membrane comprises a plurality of stiffening members attached to a first flexible sheet. Preferably each stiffening member comprises a plate which is substantially vertical when the wall section is at the second position. Preferably each stiffening member is vertically spaced when the wall section is at the second position, thus defining a foldable portion interposing adjacent stiffening members. Preferably a foldable portion is provided at each fixing location and at a location between adjacent first beam members.

The membrane may comprise a second flexible sheet such that the plurality of stiffening members are sandwiched between the first and second flexible sheets. Preferably a membrane is provided at each longitudinal edge of the first beam members.

In a second embodiment of the invention, preferably the membrane comprises a flexible sheet reliable on a winding drum. Preferably the winding drum is buoyant and movably supported to the fixed support member. Alternatively, the winding drum is rotatably supported within the trough section and an upper edge of the membrane is fixed to a float member. Preferably the fixed support member includes a vertical gearing rack and the winding drum includes a corresponding pinion such that the membrane is unwound as the wall section moves towards the second position. Preferably the sizing of the rack and pinion gearing is selected such that the membrane unwinds at a rate which corresponds to the rate at which the winding drum rises as the wall section moves towards the second position.

Preferably the winding drum is coupled to a top beam. Preferably the top cover is movably supported to the support member. Preferably the wail section includes a cable having an upper end attached to the top cover.

Preferably each of the plurality of first beam members are attached at a predetermined distance along the cable to define the vertical spacing.

Preferably each first beam member is threaded on the cable. Preferably each first beam member is cylindrical.

Preferably a plurality of wall sections are provided. Preferably a plurality of support members are provided. Preferably each wall section is operationally independent from the other wall sections. Alternatively, each wall section may be operationally coupled to one or more of the other wall sections.

Preferably a second beam member is provided at the upper end of each support member for structurally connecting each support member.

According to a second aspect of the present invention, there is provided a method of erecting a collapsible barrier comprising: providing a wall section within a trough section such that the wall section is substantially contained within the trough section, wherein the wall section includes a barrier membrane and at least one portion of the barrier membrane is flexible; providing means for moving the wall section to a position in which the wall section extends substantially vertically from the trough section; laterally supporting the wall section, using a plurality of first beam members, at the extended position; and vertically spacing apart the first beam members when the wall section is at the extended position.

Preferably the moving means comprises a buoyant wall section such that, as the water level in the trough rises beyond a predetermined level, the wall section rises under the action of buoyancy with the water level in the trough section.

Alternately or in addition, the moving means may comprise actuation means for moving the wall section to the extended position. The method may include providing one or more sensors and the actuation means is operable in response to the signal from the or each sensor.

Preferably the method includes providing a support member adapted to support the extended wall section.

Preferably the trough section includes one or more bores extending into the ground from the base of the trough section and at least a portion of the support member is provided within the or each bore when the wall section is at the first position. Preferably at least a portion of the support member is buoyant. Alternatively, the support member comprises one or more fixed columns which extend vertically from the trough section and the wall section is movably supported by the support member. Preferably the method includes dissipating water entering the trough section. Preferably the method includes providing a drainage member which is in fluid communication and exterior to the trough section.

Preferably each of the first beam members is buoyant.

In a first embodiment of the invention, preferably the method includes unfolding the membrane as the wall section moves to an extended state. Preferably the step of unfolding the membrane includes providing the membrane with a plurality of stiffened portions and foldable portions.

In a second embodiment of the invention, preferably the method includes unrolling the membrane from a winding drum as the wall section moves to an extended state. Preferably the winding drum is buoyant.

Preferably the support member includes a vertical gearing rack and the winding drum includes a corresponding pinion such that the membrane is unwound as the wall section moves towards the second position.

An embodiment of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

Fig. 1 is a front view of a barrier apparatus according to a first embodiment of the invention with the wall section at the second position and the membrane removed for clarity;

Fig. 2 is a plan view of the trough section and support member of the barrier apparatus of Fig. 1 ; Fig. 3 is a side view of the barrier apparatus of Fig. 1 with the wall section (a) at the second position, (b) at the first position, and (c) at the first position and showing the external drainage member;

Fig. 4 is a front view of a first beam member of the barrier apparatus of Fig. 1 ;

Fig. 5 is a plan view of the first beam member of Fig. 4;

Fig. 6 is a detailed front view of a portion of two first beam members and a portion of the membrane of the barrier apparatus of Fig. 1 ;

Fig. 7 is a side view of a barrier apparatus according to a second embodiment of the invention which includes an insert;

Fig. 8 is a plan view of the trough section and support member of the barrier apparatus of Fig. 7;

Fig. 9 is a front view of a barrier apparatus according to a third embodiment of the invention with the wall section at the second position and the membrane removed for clarity;

Fig. 10 is a plan view of the trough section and support member of the barrier apparatus of Fig. 7;

Fig. 11 is a side view of the barrier apparatus of Fig. 7 with the wall section (a) at the second position, and (b) at the first position; and

Fig. 12 is a detailed plan view of a portion of the barrier apparatus of Fig. 7. Fig 1 shows a barrier apparatus according to a first embodiment of the invention. The apparatus comprises a number of barriers 10 connected together. The apparatus may be attached at one or both ends to a building 100.

Each barrier 10 comprises a section of trough 20 and a wall section 30. The wall section 30 is movable between a first position, as shown in Fig 3(b) and 3(c), in which the wall section 30 is contained within the trough 20, and a second position, as shown in Fig 1 and Fig 3(a), in which the wall section 30 extends vertically from the trough 20.

The apparatus includes five first beam members 32 which are slidably connected at each end to a support member 40 and vertically spaced when the wall section 30 is at the second position.

The wall section includes a flexible barrier membrane 50 adjacent to each longitudinal edge of the first beam members 32, which is shown in Figs 3 and 6. The membrane 50 provides a barrier surface and includes portions 52, 54 which are flexible such that the wall section 30 may collapse as it moves to the first position. This is best seen in Fig 6.

The first membrane 50 on the far side of the apparatus with respect to the water level 100 provides the barrier surface. The second membrane 50 on the near side of the apparatus with respect to the water level 100 is primarily intended to prevent damage to the apparatus, such as from debris in the water.

The membrane 50 is typically formed from a polyethylene material. The membrane 50 can be formed from a material which inhibits biological growth on the surface of the membrane 50. An example of a suitable material is lko Spectraplan™.

The support member 40 structurally supports the wall section 30 when the wall section 30 is at the second position. The support member 40 comprises a rigid hollow cylindrical column provided at each end of the first beam members 32. Each support member 40 typically is formed from steel and has a length of around 5 m. Adjacent support members 40 are spaced apart at a typical distance of 3 m. The trough 20 includes a number of bores 22 which extend into the ground from the base 24 of the trough 20 to a depth of around 5.5 m. A shaft 40 is provided in each of the bores 22 and is extendable from the bore 22. A sleeve (not shown) is provided in each bore 22 and guide members 26 are provided between the shafts 40 and sleeves to ensure smooth sliding.

Each shaft 40 has a capped lower end 42. Since each shaft is hollow, the shafts have a buoyancy when the lower end 42 is acted upon by water within the bore 22.

The trough 20 typically has an internal depth of around 900 mm. The top edge of the trough 20 is slightly higher than ground level. The trough 20 includes a number of channels 28 at the base 24 of the trough 20 for dissipating water which enters the trough 20. A drainage member 60, which is in fluid communication with the channels 28, is provided exterior to the trough 20.

As shown in Figs 4 and 5, the first beam members 32 are substantially horizontal plates. The plates are formed from a lightweight material such as a composite or a foamed plastic. An aperture 34 is provided at each end for receiving a shaft 40. The end portions are only half as thick as the rest of the beam member so that two beam members can overlap and connect to a single shaft 40. Spacers 36 are provided so that there is a gap between the beam members when the wall section is at the first position.

The membrane may be formed from two flexible sheets which sandwich a number of stiffening members 56. However, a single flexible sheet is sufficient in most applications. Adjacent stiffening members 56 are vertically spaced apart when the wall section is at the second position and this defines the flexible portion 54 of the barrier membrane. The membrane 50 is fixed to each of the first beam members 32, such as by welding. The fixing of the membrane to the first beam members defines the vertical spacing of the first beam members when the wall section 30 is at the second position.

The membrane is sealably fastened to the base of the trough 20. As the wall section 30 moves to the first position, the membrane 50 folds in a concertina manner and is stored within the trough 20 as shown in Fig 3b and 3c.

A top beam 70 is connected to the upper end of each of the shafts 40. This top beam 70 closes the trough 20 when the wall section 30 is at the first position. The top beam 70 is also formed from a lightweight material such as a composite or a foamed plastic.

Each shaft 40 typically has a mass of 350 kg and a gross buoyancy of 560 kg. Each first beam member 32 typically has a mass of 60 kg and a gross buoyancy of 190 kg. The top beam 70 and membrane 50 typically have a mass of 200 kg and 10 kg respectively and a have substantially no buoyancy. In use, the wall section 30 is at the first position as shown in Fig 3b and 3c. The top beam 70 closes the trough 20 and provides a walkway. If the water level 100 begins to rise, water will first be communicated to within the trough 20 via the drainage member 60. The channels 28 will dissipate the water within the trough 20. Water is free to enter the bores 22 and, as the water level rises, water will act upon the lower end 42 of the shafts 40 such that the wall section 30 will begin to rise.

As the level of water 100 on the ground increases, water will flow over the top of the trough walls. The trough 20 will begin to fill and the buoyancy of the first beam members 32 will also assist in raising the wall section 30.

Water will be contained on one side of the wall section. This water will impart a significant lateral load upon the barrier apparatus. The shafts 40 and first beam members 32 and top beam 70 provide the structural resistance to this loading. The first membrane 50 need only provide the barrier surface for containing the water. The second membrane 50 prevents damage to the barrier apparatus.

When the water level 100 decreases, the wall section 30 will lower towards the first position. Water remaining in the bore 22 will tend to seep away into the ground if the barrier apparatus is a sufficient distance from the water course. At the first position, the membrane 50 is folded and compact such that the depth of the trench 20 may be significantly less than the height of the wall section when extended.

Figs 7 and 8 show a barrier apparatus according to a second embodiment of the invention. Like features are given like reference numerals. The barrier apparatus is similar to the first embodiment except that the support member 40 comprises a fixed column. Also, the wall section 30 is provided within an insert or cassette 28 which is inserted into the trough 20. The insert 28 has a width which corresponds to the width of the trough 20, and a length 29 which is slightly less than the distance between two columns or between one column 40 and a facing wall 41 (as shown in Fig 8). The arrangement of the second embodiment allows each wall section 30 to be operationally independent from any other wall sections provided. Also, the provision of the insert 28 simplifies transportation and installation.

Fig 9 shows a barrier apparatus according to a third embodiment of the invention. Like features are given like reference numerals.

As before, the apparatus comprises a number of barriers 10, and each barrier 10 comprises a section of trough 20 and a wall section 30. The wall section 30 is movable between a first position, as shown in Fig 11(b), in which the wall section 30 is contained within the trough 20, and a second position, as shown in Fig 9 and Fig 11(a), in which the wall section 30 extends vertically from the trough 20. The apparatus includes five first beam members 32 which are slidably coupled at each end to a support member 40 and vertically spaced when the wall section 30 is at the second position. The wall section also includes a flexible membrane 50.

In this embodiment, each first beam member 32 comprises a hollow cylinder formed from a lightweight material such as glass reinforced plastic. The diameter of each cylinder is typically 220 mm. The flexible membrane 50 is located adjacent to the first beam members 32 and each first beam member 32 laterally supports the membrane 50 when the wall section 30 is at the second position. The membrane 50 provides a barrier surface and is fully flexible such that the membrane 50 is reliable as the wall section 30 moves to the first position.

The support member 40 extends vertically from the base of the trough 20 and is immovable. The spacing between adjacent support members 40 is typically 5 m. The support member 40 structurally supports the wall section 30 when the wall section 30 is at the second position. The support member 40 may comprise a box section column or a number of connected I or C section columns or the like. The columns provide a guide channel 42 in which the first beam members 32 may move vertically.

In this embodiment, the apparatus includes a buoyant winding drum 80 which is movably supported to the fixed support member 40. The winding drum 80 comprises a capped hollow cylinder formed from a lightweight material such as glass reinforced plastic and having a typical diameter of 500 mm. An additional capped cylinder 84 formed from the same material and having the same diameter may be provided for additional buoyancy. However, the additional cylinder 84 may not always be necessary.

A lower edge of the membrane 50 is sealably attached to the base of the trough 20. An upper edge of the membrane 50 is attached to the outer surface of the winding drum 80. A pinion 82 is provided at each end of the winding drum 80 which engages with a vertical gearing rack 44 provided at the support member 40. As the winding drum 80 moves vertically, the rack 44 and pinion 82 cause the membrane 50 to be wound or unwound. The sizing of the rack and pinion gearing can be selected such that the membrane 50 winds or unwinds at a rate which corresponds to the rate at which the winding drum 80 falls or rises. The winding drum 80 is movably coupled to a top beam 70 which is movably supported to the support member 40. This top beam 70 closes the trough 20 when the wall section 30 is at the first position. The top beam 70 includes a water inlet to allow water to enter the trough 20 when the wall section 30 is at the first position.

The wall section 30 includes a cable 72 attached at one end to the top beam 70 and at the other end to the base of the trough 20. Each of the first beam members 32 are attached at a predetermined distance along the cable 72. This defines the vertical spacing between the first beam members 32 when the wall section 30 is at the second position.

The top edge of the trough 20 is slightly higher than ground level. The trough 20 includes a number of drainage holes 29 at the base 24 of the trough 20 for draining water within the trough 20 during normal conditions. The apparatus may include the drainage member of the first embodiment.

In use, the wall section 30 is at the first position as shown in Fig 11 (b). The top beam 70 closes the trough 20 and provides a walkway. The membrane 50 is substantially fully wound on the winding drum 80. If the water level begins to rise, water will enter the trough 20. As the water level rises, water will act upon the buoyant winding drum 80 which will begin to rise. As the winding drum 80 rises, the membrane 50 is unwound.

The top beam 70 also rises and pulls the cable 72 and thus the first beam members 32 upwards. The membrane 50 is therefore adequately supported during movement to the second position. At the second position, the membrane 50 provides the barrier surface for containing water on one side of the wall section 30. The support member 40 and first beam members 32 and top beam 70 provide the structural strength of the apparatus.

When the water level decreases, the wall section 30 will lower towards the first position. At the first position, the membrane 50 is rolled on the winding drum and is compact such that the depth of the trench 20 may be significantly less than the height of the wall section when extended.

Various modifications and improvements can be made without departing from the scope of the present invention. For example, the wall section need not be raised using buoyancy. In anti-terrorism applications, the membrane can be formed from a different material which is impact resistant such as Kevlar. Alternatively or in addition, the beam members can be formed from an impact resistant material. The beam members can be arranged to be close together when the wall section is at the second position to limit the likelihood of an impacting object passing between adjacent beam members. Alternatively or in addition, a top portion of the wall section may be rigid and non-collapsible and impact resistant. This still allows an apparatus which is compact and has a wall section that may be stored in a trough which is of a depth less than the height of the wall section.

Claims

1. A barrier apparatus comprising one or more barriers, the or each barrier comprising: a trough section; and a wall section movable between a first position in which the wall section is substantially contained within the trough section and a second position in which the wall section extends substantially vertically from the trough section, wherein the wall section includes: a barrier membrane, wherein at least one portion of the barrier membrane is flexible such that the wall section is in a collapsed state when the wall section is at the first position; and a plurality of first beam members for laterally supporting the barrier membrane when the wall section is at the second position, wherein the first beam members are vertically spaced apart when the wall section is at the second position.

2. A barrier apparatus as claimed in Claim 1 , wherein the apparatus is a flood prevention barrier apparatus, and wherein at least a portion of the wall section is buoyant.

3. A barrier apparatus as claimed in Claim 1 , wherein the apparatus is adapted to provide protection from invasion or attack.

4. A barrier apparatus as claimed in Claim 3, wherein the barrier membrane is formed from a material which is resistant to attacks or impacts.

5. A barrier apparatus as claimed in any preceding claim, including actuation means for moving the wall section between the first position and the second position.

6. A barrier apparatus as claimed in any Claim 5, including one or more sensors, and wherein the actuation means is operable in response to the signal from the or each sensor.

7. A barrier apparatus as claimed in any preceding claim, including a support member adapted to support the extended wall section.

8. A barrier apparatus as claimed in Claim 7, wherein the support member is vertically extendible from the trough section.

9. A barrier apparatus as claimed in Claim 7 or 8, wherein the trough section includes one or more bores extending into the ground from the base of the trough section and at least a portion of the support member is provided within the or each bore when the wall section is at the first position.

10. A barrier apparatus as claimed in Claim 7, wherein the support member comprises one or more fixed columns which extend vertically from the trough section and the wall section is movably supported by the support member.

11. A barrier apparatus as claimed in any preceding claim, wherein the wall section is provided within an insert which is insertable into the trough section.

12. A barrier apparatus as claimed in any of Claims 7 to 11 , wherein the support member is coupled to the wall section and moves with the wall section as it moves from the first position to the second position.

13. A barrier apparatus as claimed in any of Claims 7 to 12, wherein the support member comprises one or more hollow cylindrical shafts which are closed at at least the lower end.

14. A barrier apparatus as claimed in any preceding claim, including one or more channels provided at the base of the trough section for dissipating water entering the trough section.

15. A barrier apparatus as claimed in Claim 14, wherein the or each channel is in fluid communication with a drainage member provided exterior to the trough section.

16. A barrier apparatus as claimed in any preceding claim, wherein the barrier apparatus forms a continuous boundary so as to provide a container for substances within the boundary when the wall section is at the second position.

17. A barrier apparatus as claimed in any preceding claim, wherein the barrier membrane is formed from a polyethylene material.

18. A barrier apparatus as claimed in any preceding claim, wherein the barrier membrane is formed from a material which inhibits biological growth on the surface of the barrier membrane.

19. A barrier apparatus as claimed in any preceding claim, wherein the barrier membrane is fixed at a fixing location to each of the plurality of first beam members, and wherein the distance between the fixing locations defines the vertical spacing of the first beam members when the wall section is at the second position.

20. A barrier apparatus as claimed in any preceding claim, wherein each of the first beam members comprises a plate member which, in use, is substantially horizontal.

21. A barrier apparatus as claimed in any preceding claim, wherein the barrier membrane comprises a plurality of stiffening members attached to a first flexible sheet.

22. A barrier apparatus as claimed in Claim 21 , wherein each stiffening member is vertically spaced when the wall section is at the second position, thus defining a foldable portion interposing adjacent stiffening members.

23. A barrier apparatus as claimed in any of Claims 1 to 18, wherein the barrier membrane comprises a flexible sheet reliable on a winding drum.

24. A barrier apparatus as claimed in Claim 23, wherein the winding drum is buoyant and movably supported to the support member.

25. A barrier apparatus as claimed in Claim 23 or 24, wherein the fixed support member includes a vertical gearing rack and the winding drum includes a corresponding pinion such that the membrane is unwound as the wall section moves towards the second position.

26. A barrier apparatus as claimed in Claim 25, wherein the sizing of the rack and pinion gearing is selected such that the membrane unwinds at a rate which corresponds to the rate at which the winding drum rises as the wall section moves towards the second position.

27. A barrier apparatus as claimed in any of Claims 23 to 26, wherein the winding drum is coupled to a top beam, and wherein the wall section includes a cable having an upper end attached to the top cover, and wherein each of the plurality of first beam members are attached at a predetermined distance along the cable.

28. A method of erecting a collapsible barrier comprising: providing a wall section within a trough section such that the wall section is substantially contained within the trough section, wherein the wall section includes a barrier membrane and at least one portion of the barrier membrane is flexible; providing means for moving the wall section to a position in which the wall section extends substantially vertically from the trough section; and laterally supporting the wall section, using a plurality of first beam members, at the extended position; and vertically spacing apart the first beam members when the wall section is at the extended position.

29. A method as claimed in Claim 28, wherein the moving means comprises a buoyant wall section such that, as the water level in the trough rises beyond a predetermined level, the wall section rises under the action of buoyancy with the water level in the trough section.

30. A method as claimed in Claim 28 or 29, including unfolding the membrane as the wall section moves to an extended state.

31. A method as claimed in Claim 30, wherein the step of unfolding the membrane includes providing the membrane with a plurality of stiffened portions and foldable portions.

32. A method as claimed in any of Claims 28 to 29, including unrolling the membrane from a winding drum as the wall section moves to an extended state.

33. A method as claimed in Claim 32, wherein the winding drum is buoyant.

34. A method as claimed in Claim 32 or 33, including providing a support member, and wherein the support member includes a vertical gearing rack and the winding drum includes a corresponding pinion such that the membrane is unwound as the wall section moves towards the second position.

35. A barrier apparatus as claimed in any of Claims 1 to 27, wherein a plurality of wall sections are provided, and wherein each wall section is operationally independent from at least one other wall section.