GB2456878A

GB2456878A - Automatic flood barrier system

Info

Publication number: GB2456878A
Application number: GB0801855A
Authority: GB
Inventors: Matthew Smyth
Original assignee: Individual
Current assignee: Individual
Priority date: 2008-02-01
Filing date: 2008-02-01
Publication date: 2009-08-05
Also published as: GB0801855D0

Abstract

The invention relates to a flood barrier system which is reliant on flood conditions to raise the system from or near ground level to a predetermined height. Flood water enters the concrete trench 1 which houses a float 4 over which is draped a flexible, impermeable membrane 5 tailored to size and secured to both sides of the trench 1 and the float 4. The flood water raises the float 4 which, in turn, lifts the membrane 5. At maximum height the membrane 5 will be tense thereby strengthening the barrier. Covers 8, which are hinged to the dry side of the trench, are also tethered to the flood side by straps 10 which hold the cover 8 against the float 4, further adding to the strength of the system. The system is suitable for use in flood situations where hydrostatic loading and impact from flood borne debris would cause inferior systems to fail.

Description

Self Rising Flood Barrier This invention relates to a flood barrier system which rises automatically due to the presence of flood waters.

Flood defence systems already exist to contain rising water levels in rivers, lakes and similar thereby preventing consequent damage to surrounding land and property. Some of these systems are permanent, most notably walls, dams, bunds or similar and can be visually prohibitive when floods recede. Additionally, permanent systems may not be practical where thoroughfares and access points are located.

Alternative systems can be of a temporary nature such as sandbags and demountables which require being taken from storage to a site and erected before or during a flood. The procedure is reversed when floods recede.

Further systems of a semi-permanent nature are known to rise from ground level and driven by rising water levels to a predetermined height. Typically, these depend on buoyant members fixed to lids which generally cover trenches. The trenches fill with flood water, raise the buoyant members and consequently lift the lids which are intended to provide the flood barrier. Other systems have similar operation but also include separate moving buoyant members coupled with a membrane apparatus. All such systems tend to operate from shallow trenches aimed at reducing installation and manufacturing costs. Such systems generally result in flood barriers of low strength and poor resistance to hydrostatic load and impact from floating debris which is very common during flooding. The consequent costs of a failed system tend to be many times greater than the aforementioned savings.

The present invention provides an unobtrusive flood defence barrier which is self rising under the influence of rising flood waters and comprises: a continuous concrete trench; and a continuous impermeable, flexible membrane fixed and sealed to the top of the trench on all sides; and a plurality of float members sited in the trench and under the membrane and; a plurality of interlocking trench covers hinged to one side and resting on the other side of the trench above the membrane and float members.

The resultant height of the raised barrier is achieved by the height of the float when raised by the flood waters. Flood waters, on entering the trench, lift the buoyant floats to a height limited by fixed stops in the trench. The membrane, having been tailored to predetermined dimensions, is raised by the floats. At maximum height the membrane is under tension thus contributing to the structural stability of the barrier. The hinged covers are also raised by the floats and pivot upwards to a height similar to that achieved by the floats. At maximum height the covers are restrained by tethers anchored to the concrete trench on the flood side. The raised covers provide additional stability to the floats and protection against damage to the dry side of the membrane.

An embodiment of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 shows an end view in cross section of the flood barrier at rest in the closed position.

Figure 2 shows an end view in cross section of the flood barrier at work and in the raised position.

In figure 1 an excavated site is partially filled with concrete and shaped to form a concrete trench 1. The concrete surface 2 is sealed with suitable water resistant materials which may range from liquid polymeric coatings to solid reinforced polymeric mouldings.

Float 4 is composed of a core of lightweight buoyant material preferably low density, polymeric foam encased completely with a rigid polymeric material, preferably GRP, composed of glass or mineral based fibres reinforcing a type of polymeric resin. Float 4 has an inbuilt GRP base with projections 3.

A flexible impermeable membrane 5, tailored to predetermined dimensions, is placed on the float 4 with the centre lines of both coinciding. The membrane 5 is then secured by fasteners 6 part way down each side of the float 4. The opposing edges of membrane 5 are anchored to the trench 1 with rigid stop plates 7 which assist in forming sealed sides. Correct location of the membrane 5 at this point permits the float 4 to sit freely on the base of trench 1.

Interlocking trench cover 8 is fixed with suitable hinges 9 to the dry side of the trench 1 and is made to a dimension that will allow the cover 8 to pivot to the same height as the raised float. Flexible water resistant tethering straps 10 are fastened in a preset location to the underside of the cover 8 and anchored to the flood side of the trench I in a position that permits full opening of the system and follows the contour of the membrane 5.

Figure 2 shows the barrier system in raised position. Flood waters initially gather in trough 11 before entering trench I at the base through pluralities of vertical inlet pipes 12. Alternatively, and preferably, the inlet pipes 12 may run in a more horizontal axis towards the flood source thereby commencing the filling of trench I at an earlier stage in the flood event. The geography and terrain of the site will determine this.

Float 4 will continue to rise until impeded by; firstly, the float projections 3 engaging with stop plates 7; secondly, the membrane 5 unravelling to full height and under tension; thirdly, the tethering straps 10 also unravelling to full height and under tension.

Under normal conditions in the absence of flooding, cover 8 may be utilised for pedestrian and light traffic. The underside of cover 8 should be close to, or rest upon, membrane 5 which, in turn, rests on float 4. This minimises deflection of cover 8 when a load is applied. During flooding cover 8 will protect membrane 5 against malicious or accidental damage from the dry side.

The covers 8 would preferably be of an interlocking design to minimise unauthorised interference under normal conditions and to rise together when flooding commences.

In the raised position the side of membrane 5 facing the flood will be smooth and streamlined sufficiently to minimise detrimental effects of fast flowing waters.

Vents 13 are made at selected points in the top of the membrane 8 to permit air to be expelled during flooding and water to be expelled after flooding recedes.

Holes 14 are located in the base of trench I to prevent buoyant movement of the trench I in the event of rising ground water. The holesl4 also assist in drainage to the subsoil after flooding.

The barrier system is modular and pluralities of floats 4 and covers 8 can be located in a single trench I with a single membrane 5 and configured to suit a wide range of contours and dimensions While references throughout this document have related to water flooding, the system entailed herein can also be used as a semi-permanent fluid retention system to contain a wide variety of liquids released accidentally or otherwise.

Claims

Claims 1. A flood barrier system which rises automatically due to the presence of flood waters.
2. A flood barrier system according to claim 1, which is structurally stable enough to withstand excessive loads and impact inflicted by flood waters.
3. A flood barrier system according to claims 1 and 2, in which a continuous concrete trench is cast in an excavated site.
4. A flood barrier system according to claim 1, in which the concrete trench exposed faces are sealed to provide a water resistant surface.
5. A flood barrier system according to claim 1, in which a plurality of float members rise out of the trench when flooding occurs.
6. A flood barrier system according to claim 1, in which a continuous membrane is fixed uniformly over the upper portion of the float members.
7. A flood barrier system according to claim 1, in which the continuous membrane is under tension when fully raised.
8. A flood bamer system according to claim 7, in which membrane tension is achieved by the upward thrust of the float members on one part and fixings forming a seal between the membrane and the concrete trench on the other part.
9. A flood barrier system according to claim 1, in which a plurality of interlocking trench covers are hinged to dry side of the concrete trench and rest on the wet side.
10.A flood barrier system according to claim 1, in which a plurality of tethering straps have one end fixed to the underside of the trench covers and the other end anchored to the wet side of the concrete trench.
11. A flood barrier system according to claim 10, in which the tethering straps unravel and atlain tension when the barrier system is fully raised.
12.A flood barrier system according to claims 2 and 11, in which the tethering straps hold the trench cover firmly against the membrane and float assembly thus protecting the membrane from damage.
13. A flood barrier system according to claim 1, in which the float members have a base designed to add weight to the bottom of the float thus ensuring the float remains in an upright position.
14. A flood barrier system according to claim 13, in which the base is extended beyond each side of the float so as to engage with fixed stops on the concrete trench thereby limiting the upward movement of the float and membrane.
15. A flood barrier system according to claim 1, in which inlets with entry points lower than the closed cover, permit flood water to enter the concrete trench.
16.A flood bamer system according to claim 1, in which holes are provided in the base of the concrete trench to allow entry of rising ground water and to assist drainage to subsoil after floods recede.
17.A flood barrier system according to claim 1, in which venting holes are made at the top of the membrane at selected locations to assist in air removal when the barrier is rising and to allow water removal as the barrier is descending.
18.A flood barrier system according to claim 1, in which the cover can be used for pedestrian traffic when the system is closed.
19.A flood barrier system according to claimi and 18, in which the centre line of the underside of the covers rests on or close to the centre line of the top of the floats to minimise deflection on the covers when loads are applied.
20.A flood barrier system according to all previous claims, which may be manufactured in modular sections.
21.A flood barrier system according to all previous claims, in which alterations, modifications and improvements can be made without departing from the scope of the present invention.