Patent Publication Number: US-8523485-B2

Title: Flotation structure for buoyant flood protection barrier and barrier incorporating, such a structure

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of prior Application No. GB 0803927.3, filed 1 Mar. 2008. 
     BACKGROUND OF THE INVENTION 
     This invention relates to a flotation structure for a buoyant flood protection barrier. The invention also relates to a buoyant flood protection barrier incorporating such a flotation structure. 
     A buoyant flood protection barrier is known, for example, from GB-A-2 397 086 and comprises flotation structure including a flotation body to which is secured a flexible, waterproof barrier. The flotation body is provided with guide wheels which run in guide rails which are positioned around a property to be protected. 
     One problem that arises with the known flotation structure is that the flexible panels do not always open in an ideal manner, which can lead to distortion and jamming of the hinged panels. 
     BRIEF SUMMARY OF THE INVENTION 
     It is therefore an object of the present invention to provide a flotation structure for a buoyant flood protection barrier which overcomes or at least ameliorates the abovementioned disadvantage. 
     According to one aspect of the present invention there is provided a flotation structure for a buoyant flood protection barrier comprising: 
     a flotation body adapted to rise and fall with flood water; 
     a flexible membrane sealed at an upper region thereof to the flotation body and sealed at a lower region thereof; 
     a plurality of panels hinged by means of hinge pins about substantially parallel horizontal axes, a topmost panel being hinged to the flotation body, a lowermost panel being hinged substantially at ground level, and intervening panels being hinged to each other; and
 
a scissor arrangement pivotably mounted at an upper end to the flotation body and pivotably mounted at a lower end and provided with a pivot pin at a crossing point of arms of the scissor arrangement, the pivot pin being secured to a member provided on at least one of the hinge pins.
 
     The length of the arms of the scissor arrangement may be selected such that the arms cross at a point adjacent to each of the horizontal axes which is adjacent to the scissor arrangement. One or more intermediate crossing points may be provided if desired. 
     The member provided on at least one of the hinge pins may be rotatable about the hinge pin and/or may be slidable along the hinge pin. 
     The flotation structure may include one or more support posts provided on that side of the panels remote from the membrane. The support posts may be movable upwardly and downwardly in a sleeve set in the ground. A lower end of the or each support post may be provided with at least one roller adapted to bear against an inner surface of the sleeve. A plurality of rollers may be provided, spaced around the periphery of the support post. An upper end of the sleeve may be provided with at least one roller adapted to bear against an outer surface of the support post. A plurality of rollers may be provided, spaced around the periphery of the sleeve. 
     According to another aspect of the present invention there is provided a buoyant flood protection barrier comprising at least two flotation structures as hereinbefore defined and including a plurality of flexible rods extending between the end of one flotation structure and the end of an adjacent flotation structure for supporting the membrane between the two flotation structures. 
     The flexible rods may be connected to the outer region of the flotation structures. 
     The flexible rods may be arranged to be connected to the two flotation structures at different levels. When connected to the outer regions of the hinged panels the angle of the rods changes relative to the horizontal as the barrier is raised and lowered. 
     For a better understanding of the present invention and to show more clearly how it may be carried into effect reference will now be made, by way of example, to the accompanying drawings in which: 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         FIG. 1  is a perspective view of one embodiment of a flotation structure for a buoyant flood protection barrier according to the present invention; 
         FIGS. 2 and 3  show part of the flotation structure shown in  FIG. 1 , but to a larger scale; 
         FIG. 4  is a perspective view showing a corner arrangement of a buoyant flood protection barrier incorporating flotation structures shown in  FIG. 1 ; 
         FIGS. 5 to 7  are plan views of the corner arrangement shown in  FIG. 4 ; and 
         FIGS. 8 and 9  are diagrammatic perspective views illustrating support posts forming part of the flotation structure according to the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  shows a flotation structure for a buoyant flood protection barrier which includes an elongate flotation body  1  which is adapted to rise and fall, floating on the surface of the water, as flood levels rise and fall. Attached to the bottom of the flotation body  1  is a flexible, waterproof membrane  3 , the membrane being sealed in the upper region thereof to the flotation body  1  and at the lower region thereof around a property or area to be protected. For example, the membrane  3  may be sealed to a housing (or trench)  4  in which the flotation structure is stored when not in use. The membrane  3  extends entirely around the outer perimeter of the barrier and is supported by a plurality of substantially rigid panels  5  which are hinged about substantially parallel horizontal axes. The topmost panel  5  is hinged to the flotation body  1 , the lowermost panel is hinged substantially at ground level, and the intervening panels are hinged to each other. The panels in turn are supported against a plurality of support posts  7  to reduce deflection of the panels. 
       FIGS. 2 and 3  illustrate in more detail a mechanism for ensuring even opening of the hinged panels  5 . A scissor arrangement  9  is positioned alongside the panels  5  and rises and falls with the panels. Arms  11 ,  13  of the scissor arrangement are pivotably mounted at the upper end of the arrangement to the flotation body  1  and are pivotably mounted at the lower end substantially at the level of the bottom of the membrane  3  (which may be below ground level in housing  4 . The length of the arms  11 ,  13  is selected such that the arms cross at a point  15  adjacent to each of the axes about which the panels pivot relative to each other and which is adjacent to the scissor arrangement, although one or more intermediate crossing points may be provided if desired to avoid the use of arms of excessive length. That is, the panels  5  are each hinged to one another, with the result that when folded, or partially folded, the hinge between one pair of panels will be adjacent to the scissor arrangement  9 , while the adjacent hinge will move progressively away from the scissor arrangement as the panels are folded and will move progressively towards the scissor arrangement as the panels are unfolded. 
     Each crossing point  15  is also a pivot point for the arms  11 ,  13  and a pivot pin  17  is secured to or formed integrally with a panel support member  19 . The panel support member extends in the axial direction of the hinge between two panels  5  and is generally cylindrical in shape, while the axis of the pivot pin  17  is substantially perpendicular to the axis of the member  19 . The member  19  is formed with a bore  21  and is mounted on a hinge pin  23  which secures adjacent panel members together. The panel support member  19  is preferably rotatable about the hinge pin  23  and slidable along the hinge pin to accommodate any relative movement between the panels  5  and the scissor arrangement  9 . 
     As the flotation body  1  rises it pulls both the panels  5  and the scissor arrangement  9  upwardly. However, the scissor arrangement ensures that the hinge pins  23  are all spaced apart by the same distance, thereby minimising buckling and the risk of jamming of the panels. The equal spacing is also maintained as the flotation body falls. 
       FIGS. 4 to 7  illustrate the manner in which corners of a buoyant flood protection barrier comprising two flotation structures are bridged by the membrane  3 . Without any physical support, the membrane  3  (only part of which is shown in  FIGS. 5 to 7 ) would bulge inwardly between the ends of each flotation structure and could tear or become trapped and be damaged. To prevent this, a plurality of rods  25  flexible material, for example a flexible or resilient synthetic material, extends at the outer edge of the flotation body  1  or a panel  5  from the end of one flotation structure to the end of an adjacent flotation structure. The rods  25  need not extend substantially horizontally, but instead may be arranged at an angle to the horizontal whereby each rod is secured at the end of a predetermined panel in one flotation structure and is secured one panel apart (up or down) at the end of an adjacent flotation structure. 
     As the barrier rises, the panels rotate, the effect of rotation being shown in  FIGS. 5 to 7 . Initially, with the panels  5  substantially horizontal, the rod  25  is substantially arcuate. However, as the barrier rises and the panels rotate, the rod  25  moves from a relatively horizontal configuration to a relatively upright configuration. At the same time, the ends of the rod move towards the inner hinge pins  23  at which the panels are supported relative to the scissor arrangement  9  (not shown in  FIGS. 4 to 7 ).  FIGS. 5 ,  6  and  7  show the barrier in progressively raised configurations. The combined effect of these two movements is to cause the middle region of the rod  25  to move outwardly from the corner between the two flotation structures. At the same time, because the distance around the perimeter of the barrier is decreasing (due to the inward movement of the panels) the membrane  3  becomes pinched by water pressure against the outside of the barrier, but is supported by the rods  25  and guided into “noses” or protrusions which are unable to collapse inwardly through any gap at the junction between the two flotation structures. 
     As the barrier falls, the rods  25  move back to a relatively horizontal configuration and take a more arcuate shape and continue to support the membrane  3  which assumes a more rounded shape across the gap between the two flotation structures. 
       FIGS. 8 and 9  show a support post  27  which rises and falls with the flotation body  1 . The figures show the arrangement from opposite sides of the flotation body. Support posts are positioned at intervals along the length of each flotation structure on the internal side of the flotation body and serve two primary functions. The support posts prevent the barrier as a whole being moved to and fro by any current that may be present in the flood water surrounding the barrier. In addition, the support posts provide support to the flotation structure and prevent or reduce inward bowing or other deformation due to water pressure. This is particularly a problem as the barrier extends towards its maximum height and the area of the barrier exposed to flood water increases, while the support attributable to the hinged panels  5  (which form a corrugated structure) diminishes. 
     Each support post  27  is mounted within a sleeve  29  which is set into the ground when the barrier is installed, the support post rising and falling within the sleeve as required. As illustrated, the support post is made of material of substantially square cross section. A plurality of outwardly extending rollers  31  are positioned around the lower end of the support post  27 , for example four rollers, one on each face, so as to facilitate movement of the support post. In addition, as shown in  FIG. 8 , a plurality of inwardly extending rollers  33  are positioned around the upper end of the sleeve  29  so as to facilitate movement of the support post  27  relative to the upper end of the sleeve  29 . In practice, the length of the support posts  27  will be determined by the anticipated maximum depth of any flood water. 
     Alternatively, a fixed support post  7  may be provided.