GB2456394A

GB2456394A - Flood defence system

Info

Publication number: GB2456394A
Application number: GB0800859A
Authority: GB
Inventors: Matthew Smyth
Original assignee: Individual
Current assignee: Individual
Priority date: 2008-01-18
Filing date: 2008-01-18
Publication date: 2009-07-22
Also published as: GB0800859D0

Abstract

A self rising flood defence system comprising two conjoined buoyant walls 7 and 9 each hinged to opposite sides of a concrete liner 5 and held in place, when subjected to flooding, by a continuous impermeable flexible membrane 10 secured to each side of the concrete liner 5 and to two slab walls (2 figure 1) forming the extreme ends of the barrier (1 figure 1). The resultant triangular shape offers resistance to hydrostatic loading and impact damage. When floods recede both walls 7 and 9 and membrane 10 retreat into the concrete liner 5 with wall 9 resting on the arch shaped wall 7 thereby increasing the flexural resistance of wall 9 allowing it to withstand loads.

Description

2456394

Self rising, double wali flood defence system

This invention relates to a flood defence system which consists mainly of two conjoined barrier walls and a membrane which rise automatically due to rising flood levels to form a triangular shaped flood defence wall capable of withstanding load and impact. The invention also relates to sealing systems at either end of the wall.

Many systems exist to contain rising water levels and thus prevent flooding of land and property. These systems mainly fall into one of the following categories;

a) Permanent barriers such as walls, dams, bunds and similar which are fixed and in situ whether or not there is flooding.

b) Temporary barriers such as demountables, sandbags and similar which are often put in place after flooding begins and removed when it stops.

c) Semi-permanent barriers which are wholly or partially buried, moving into a flood containment position by mechanical, manual or automatic means when flooding threatens and returning to their original position by the same means when the threat recedes.

Permanent barriers are disadvantageous in flood prone areas of high amenity such as waterfronts, riversides and areas of natural beauty particularly where scenic landscapes and views would be otherwise obscured by such barriers.

Temporary barriers have to be obtained and moved from storage, taken to the endangered site and erected before or during flooding.

Semi-permanent barriers which require mechanical and manual operational systems are often dependant on human and/or powered intervention which can not always be guaranteed to be available particularly during the type of weather which leads to flooding in the first place. Automatic systems of the self lifting type often employ flotation devices which are raised and lowered independently by the flood waters but these tend to have a float fixed to a single wall which is hinged to the 'dry' side of a trench. During rising and at full height the wail is tethered by straps or cables on the flood side but these can be broken or dislodged when impacted upon by flood debris such as trees or similar heavy floating objects. Straps and cables will also catch lighter debris such as branches which will build up and ultimately, like the heavier objects, present a threat to the integrity of the flood defence system causing it to fail. Furthermore, to operate efficiently such single walls must be angled to face into the flood thereby increasing stress and consequent load on the wall and tethering. Few existing systems adequately address sealing methods at extreme ends of the wall.

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This invention is in the semi-permanent, automatic category and seeks to overcome such deficiencies by the introduction of;

i) a second wall to increase the defensive properties,

ii) a continuous membrane to provide a seal and retain both walls in raised position over the length of the barrier and iii) leak resistant seal assemblies for either end of the barrier.

These aspects will now be described as follows with reference to the accompanying drawings in which;

Figure 1 illustrates a typical flood prevention barrier application.

Figure 2 shows a view in cross section of the flood barrier in closed position prior to flooding.

Figure 3 shows a view in cross section of the flood barrier in raised position during flooding.

Figure 4 shows a three stage system designed to seal each end of the flood barrier.

Figure 5 shows a view in cross section of the three stage sealing system.

In figure 1, a flood barrier 1 - shown hatched in the raised position - is located between two vertical slabs 2 which are constructed ideally from masonry products - concrete, brick or similar. Slabs 2 require having a smooth, flat rendered surface which faces on to the end of barrier 1. All of this is installed in an area in proximity to a stretch of water 3, typically river, lake or similar, which is prone to flood. The barrier can be made to suit a wide range of lengths and contours by the placing of the essential components as described below.

In figure 2 a trench 4 is partly filled with concrete and shaped to form a concrete liner 5. After curing, the concrete surface 6 is sealed with suitable water resistant materials. These can either be solid, such as polymeric mouldings or bituminous linings which can be bonded to the concrete, or liquid such as silicates or polymers which can set to form a surface coating thus providing an adequate seal. A plurality of floats 7, each composed of a core of water resistant buoyant material - such as low density polymeric foam - encased completely with a skin of rigid polymeric material such as GRP (fibreglass) composed of glass strands with reinforcing polymeric resins such as epoxy, vinyl ester, phenol, acrylic or similar, are fixed with hinges 8 to the flood side of the concrete liner 5. The floats 7

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require being arch shaped on the top surface to assist in the barrier rising operation in addition to providing improved resistance to flood debris impact and hydrostatic loading applied by the flood waters. A plurality of trench lids 9 are fixed with hinges 8 to the dry side of the concrete liner 5. The lids 9 are made to fit neatly into the recess in concrete liner 5 and require being of a weight capable of being lifted with minimum effort by the float 7. Varying the depth of concrete liner 5 and the volume of float 7 will vary the lifting power of float 7. This will permit lids 9 to be constructed in materials applicable to the intended utilisation of lids 9 when in the closed position. This use may range from pedestrian to vehicular traffic and cognisance of these factors must be taken when choosing materials for lid 9 construction. In the closed position the central area of the underside of the lid 9 requires to rest on the central area of the upper side of the arched float 7 thus providing resistance to deflection of the lid 9 when a load is applied.

A waterproof membrane 10 made from high strength flexible impermeable materials is fixed with one long edge to the 'dry' side and the opposite edge to the 'flood' side of concrete liner 5. The amount of membrane 10 between these two edges is measured such that the membrane 10 will be at full stretch when the barrier 1 is in the fully opened position. The membrane 10 is secured in part to the underside of the lid 9 and in part to the top side of the float 7. The remaining unsecured membrane 10 is folded and located in a gap between the lid 9 and the float 7 when the barrier 1 is in the closed position. The membrane 10 is also secured at either end of the barrier 1 to both slabs 2 and forms part of an end seal apparatus (described later).

Pluralities of water inlets 11 are located such that water will enter from the exterior surface opening of each inlet 11 and pass through a right angle bend into the concrete liner 5 below the hinged edge of float 7. Inlets 11 may also have horizontal entries which will allow earlier operation of the flood barrier 1 and also double as a water exit when the flood recedes.

When water enters the concrete liner 5 the float 7 will start to rise lifting the lid 9 until the process is completed by membrane 10 being fully extended. Thus float 7, lid 9 and concrete liner 5 forms a triangular barrier designed to resist impact from flood debris and provide a secure flood defence system as shown in Figure 3. Anti-flotation/drain holes 12 are located in the base of concrete liner 5. These allow rising underground water to enter the concrete liner 5 thereby preventing lifting and potentially displacing the barrier system while also permitting drainage to a soakaway or similar when the floods recede.

A three part end seal system is shown in closed position in Figure 4 and in cross section in Figure 5.

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The first part involves a predetermined amount of membrane 10 extended beyond the end of the outermost lid 13. Lid 13 has a vertical protective shield adjacent to the slab 2 to prevent damage, accidental or malicious, to the extended membrane 10 which is located behind shield. A portion of membrane 10 extension is fixed to the slab 2 with the remainder allowed to hang loose inside the vertical portion of lid 13 when in the closed position. The purpose of this is to allow the loose portion of membrane 10 to unfold and rise with the lid 13 to form a partial seal.

The second part improves the end seal further and involves the use of heavy duty brush strips such as those used for draught proofing and weather sealing applications. Brush strip 14 is fixed to the inner horizontal edge (in closed position) of lid 13 with the bristles firmly pressed against the membrane 10 portion which is fixed to the slab 2. A second brush strip 15 is fixed to the outer angled top face of the lid 13 with the bristles firmly pressed against the slab 2. When the barrier 1 rises brush strip14 will sweep the membrane 10 against the slab 2 and brush strip 15 will sweep against slab 2 finishing in a vertical position with its highest point at or above maximum barrier 1 height.

The third and final part of the seal system involves the application of two-part rubber seals typically with male/female contact. Male seal 16 is fixed to brush strip 15. Female seal 17 is fixed in a vertical position to the slab 2. It can be seen that when the barrier 1 rises to full height both seals 16 and 17 engage. By combining the extended membrane 10, brush strips 14, 15 and seals 16,17 a suitable three part sealing system results in minimising or eliminating flood waters passing the barrier 1 where it meets slabs 2.

While references throughout this document have related to water flooding the system entailed herein can also be used as a semi-permanent bund to contain all manner of liquids released accidentally or otherwise.

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Claims

1. A flood defence system having two conjoined walls with one or both constructed of buoyant materials that cause the system to open and rise automatically when subjected to flood conditions.

2. A flood defence system according to claim 1, in which one wall, hereinafter described as a lid, overlaps and rests on the other, hereinafter described as a float, when closed and in the horizontal plane.

3. A flood defence system according to any of the preceding claims, in which the I id may serve an alternative purpose as a walkway or a path when in the horizontal plane.

4. A flood defence system according to any of the preceding claims, in which the float contains sufficient buoyancy materials to lift both walls and is designed in the shape of an arch to assist in the lift and also to resist flood debris impact when raised.

5. A flood defence system according to claim 1, in which an impermeable membrane tailored to suit is secured to each side of a concrete liner and partially secured to slabs located at either end of the concrete liner.

6. A flood defence system according to claim 5, in which the membrane is partially secured to both lid and float with the unsecured part of the membrane folded and located between lid and float when in the closed position.

7. A flood defence system according to claim 1, in which the membrane forms a conjoining link between lid and float.

8. A flood defence system according to claim 1, in which a concrete liner, sealed on the internal surfaces with suitable materials to minimise escape of water, houses both walls and a membrane.

9. A flood defence system according to claim 1, in which both walls are hinged to opposite sides of the concrete liner thus forming a triangular shape with the membrane when raised due to flooding.

10. A flood defence system according to claim 1, in which flood waters enter the concrete liner at lowest level via vertical or horizontal inlets and exit through the same as waters recede.

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11. A flood defence system according to claim 1, in which an outlet is installed in the centre of the concrete liner base to permit water ingress in the event of rising ground water and also to assist in drainage as waters recede.

12. A flood defence system according to claim 1, in which the components can be modular and made to suit particular applications.

13. A flood defence system according to claim 1, in which the system can be installed to suit a range of lengths and contours.

14. A flood defence system according to claim 1, in which a seal is obtained at each end of the barrier by incorporating a protective moulded lid and a sealing apparatus.

15. A flood defence system according to claim 14, in which a sealing apparatus is an extension of the membrane and a brush strip inside the lid holding the membrane in place against a vertical wall.

16. A flood defence system according to claim 14, in which a sealing apparatus is a second brush strip outside the lid and pressed firmly against the slab.

17. A flood defence system according to any of the preceding claims, in which the system is not limited to flood waters but can be used for other liquids.

17. A flood defence system according to claim 14, in which a sealing apparatus is a two part moulded male/female system which interconnect fully when the barrier is raised to maximum height.