AU2005291055A1 - Scour protection system - Google Patents

Abstract

A scour protection system comprising one or more bags placed in an underwater location to prevent scour caused by the flow of water, wherein the bags can be filled with matter in situ to form interconnecting blocks, and the visible upper surfaces of the bags resemble rocks or other features.

Description

WO 2006/037976 PCT/GB2005/003787 Scour protection system The invention to which this application relates is a system for protecting structures exposed to water from the scouring action of the water. Scour is caused by the wearing action of moving water, for example along the bed and banks of rivers, and can have serious consequences to structures exposed thereto such as the supports of bridges, due to undermining of the structure's foundations. This can result in the catastrophic collapse of many structures, leading to potential loss of life and significant rebuild costs. Structures can however be protected against these effects and there are several forms of protection currently in use around the world, in both fluvial and marine situations. One such method of scour protection is the use of fabric formwork mattresses (also known as filter-point or constant thickness mattresses). These mattresses have been used within the construction industry for approximately 40 years for protecting riverbanks, river beds, and sea beds from scour and erosion, particularly around structures. Fabric formwork mattresses essentially form a hard layer of protection, which is designed to resist the effects of scour and as such, protect structures from being undermined, and/or river banks from lateral erosion. They consist of a sandwich of high strength, generally porous, typically woven, synthetic fabric, into which micro-concrete, grout or aggregate concrete is pumped. Mattresses placed below water are laid and filled in-situ, using divers. Typically they form extensive mats, similar in shape to bedding mattresses, ranging in thickness between 100 and 350mm. The result, once the concrete has set, is a solid layer of protection that can be very effective and resistant to scour.

WO 2006/037976 PCT/GB2005/003787 2 Fabric formwork bags are also available, for underpinning works, or to provide support and/or protection to structures such as pipelines. These bags are amorphous in shape, and resemble sand-filled bags, and as such do not fit together particularly well. Articulated mattresses are also available, and are similar in most respects to filter-point mattresses but allow settlement due to flexible seams. Again, these are generally amorphous in shape, which is disadvantageous as hereinbefore described. These bags are smooth textured and when formed are white/light grey in colour, which is characteristically unnatural in appearance. There also exists preformed concrete blocks, which can be articulated or interlocking concrete blocks, but these do not enable the placement of wet concrete below water. The advantage of fabric formwork protection is that it enables the placement of concrete or grout below water, without significant risk of environmental pollution that would otherwise occur if concrete were allowed to freely enter the river, or marine environment. The use of concrete can be very effective protection against scour, but in most instances concrete cannot be placed without complete dewatering (drainage) of the area to be protected, to protect against fouling and environmental pollution from the concrete otherwise, and to provide the necessary formwork. The ability to place concrete without the need for dewatering has significant advantages over many other forms of scour protection and can lead to significant cost savings for any scour protection scheme. In addition to forming an effective means of protecting a structure, river bank or indeed any interface between water and land, the mattresses form a relatively thin form of protection, which has the WO 2006/037976 PCT/GB2005/003787 3 advantage of requiring minimal excavation to form, and is relatively quick to install. The disadvantages of fabric formwork mattresses however are significant and have resulted in this method of protection becoming unfavourable over the last 10 years or so, particularly within the UK. A disadvantage with this method of scour protection is that it forms a hydraulically smooth surface (a low mannings n value), which typically results in the scour being deflected elsewhere. Smooth surfaces will not absorb any of the erosive force of the river and can even exacerbate the scour problem elsewhere. In addition, this method produces a very un-natural appearance, being smooth, dimpled, 'sand-bag like' or mattress-like, the colour of which is off-white/concrete looking, particularly when first placed. Similarly, extensive mats are relatively inflexible and the extremities are particularly vulnerable to undermining and cracking, reducing the protection. Furthermore this method provides no environmental benefits, and the mattresses are very difficult to form protection for anything other than simple flat surfaces. Non-standard shapes/designs can be custom made but require significant time to manufacture. Mattresses are also very difficult to repair and the benefits gained by using extensive mattresses can be lost if small repairs are needed. These disadvantages make the use of fabric formwork mattresses unfavourable with consenting organisations around the world and as a result are presently of limited use as a method of protecting structures or river banks against scour.

WO 2006/037976 PCT/GB2005/003787 4 Consequently, alternative forms of protection such as rock armour or rip-rap, which are coverings of loose rocks, are usually preferred, as they are environmentally more natural and largely preferred by numerous environmental consenting groups. An aim of the present invention is to provide a scour protection system which overcomes the above disadvantages. In a first aspect of the invention, there is provided scour protection apparatus comprising one or more containment means, said containment means placed in a location to prevent scour, each of said containment means substantially filled with matter to form blocks, characterised in that at least a portion of the outer surface of said containment means is adapted to have an appearance sympathetic with at least one feature of the location. In one embodiment the containment means are bags. Typically the bags are made of fabric with a specific base shape, and are formed by connecting seams by sewing, studs, heat-welds and/or the like. Typically the bags are manufactured from any or any combination of polypropylene, polyester, nylon, hemp, elasticated fabrics, and/or the like. Thus fabric with a specific base shape is used to provide the formwork for the matter, to form a block which can be used to provide a system of interconnecting blocks. Typically the base shape and thus each block is one square metre in area, or fractions or multiples thereof to allow discontinuity of blocks. This form of construction means that the blocks can be used universally, and can be manufactured and stockpiled as empty fabric bags and thus always be available 'off the shelf'. The overall scour protection scheme is easier to design and is more flexible to accommodate and remove variations in bed profile WO 2006/037976 PCT/GB2005/003787 5 around any scour feature than with conventional systems. In addition, individual blocks can be removed and replaced if damaged for example, without having to remove any other blocks. Typically one or more blocks have an increased depth compared to the other blocks so as to be suitable for placement around the edges of the location. In one embodiment one or more sections of the bags are reinforced, stiffened and/or restrained to ensure the blocks are formed in the correct shape and shape is maintained. In one embodiment the bags are formed of foldable sheet material to allow the bags to be moved between a flattened folded configuration and an erect configuration. Typically the matter is any or any combination of grout, concrete, sand, stones, and/or other aggregate material. In one embodiment the containment means is substantially filled with the matter after being placed at the location. Typically a hose is connected to the containment means to fill the same with matter and/or release trapped air, water and/or matter. In one embodiment the containment means is provided with valve means and/or filter means to prevent escape of the matter placed therein. In one embodiment the containment means is provided with an outer layer and one or more inner layers. In one embodiment the WO 2006/037976 PCT/GB2005/003787 6 outer layer is permeable and one or more of the inner layers is impermeable. Typically the location is underwater, including any or any combination of riverbanks, river beds, sea beds, and/or the like. In one embodiment the location features are rocks, and the top surface of the containment means resembles rock armour. Typically the top surface is adapted by physical or mechanical impact and/or by the application of heat such that when the containment means has been filled with the matter, the top surface has a rough, irregular, rock-like shape. Other surfaces of the containment means can be adapted in a similar fashion as required. Alternatively, the appearance can be achieved by tailoring the fabric forming the top surface of the individual blocks to produce a rough and irregular surface, by physical restraints to the expansion of the top surface, and/or by post expansion deformation of the concrete bags after placement. The provision of this deformation and irregular surface creates a more natural appearance, and also creates a high mannings 'n' value so that the protection acts more like rock armour scour protection in absorbing some of the energy of the flow. Typically at least a portion of the containment means is coloured and/or textured to resemble features of the location. The texturing and/or colouring is of particular importance for areas that are easily visible, as discolouration of the blocks occurs naturally over time. In one embodiment, connection means are provided to connect adjacent containment means. Typically the connection means WO 2006/037976 PCT/GB2005/003787 7 includes any or any combination of zips, ties, nuts, bolts, washers, plates, hook and loop fastenings, and/or the like. In a second aspect of the invention, there is provided scour protection apparatus comprising one or more containment means, said containment means placed in an underwater location to prevent scour, each of said containment means substantially filled with matter to form blocks, characterised in that the containment means is substantially filled with the matter after being placed at the underwater location. In a third aspect of the invention, there is provided scour protection apparatus including at least one containment means formed by a sheet material defining a cavity into which matter is placed to substantially fill the same and characterised in that at least one surface if the containment means is adapted so as to have a higher mannings 'n' value than the remainder of the containment means' surfaces. In a fourth aspect of the invention, there is provided a method of providing scour protection to a location, comprising the steps of: placing containment means in a location to prevent scour; substantially filling said containment means with matter to form blocks, characterised in that at least a portion of the outer surface of said containment means is adapted to have an appearance sympathetic with at least one feature of the location. In one embodiment the adaptation also increases the mannings 'n' value of said portion. Specific embodiments of the invention are now described wherein:- WO 2006/037976 PCT/GB2005/003787 8 Figure 1 illustrates a schematic view from the side of the containment means of a scour protection system in accordance with one embodiment of the invention. Figure 2 illustrates a perspective view of the containment means of figure 1. Figure 3 illustrates a side schematic view of the containment means of figure 1 being filled. Figure 4 illustrates a plan view of a scour protection system (a) under construction with offset blocks in the location; (b) with in-line blocks; (c) with variable sized blocks; (d) as an example of a complete system. Figure 5 illustrates a side schematic view of an edge toe detail block. Figure 6 illustrates a side sectional view of a scour protection system. Figure 7 illustrates a side schematic view of adjacent blocks (a) with a butt join; (b) with an alternative butt join; (c) connected by a zip; (d) connected by an alternative zip; (e) connected with nuts and bolts; (f) connected with nuts and looped-end bolts. Figure 8 illustrates a side schematic view of a bag with a folded edge. With reference to Figures 1-2, there is illustrated containment means in the form of an individual fabric bag 1 filled with matter 5 to form a block, designed to interconnect with other blocks to cover an area and provided with a top surface 3 to act WO 2006/037976 PCT/GB2005/003787 9 like and resemble rock armour. Of course, other surfaces can be configured to resemble rock armour as required. The rock armour has an appearance sympathetic to the natural rock features of the location in this example a river bed. The shape of the bag 1 defines the bag formwork. In this example the fabric is manufactured from high strength synthetic material such as polypropylene or polyester and in this example is permeable to allow the escape of trapped air or water within the bag. Heavy duty cotton, hemp, or a similar type of fabric can also be used. However the ability to heat or physically deform such fabrics is limited and it is likely that at least the top surface 3, would need to be tailored by a variety of methods including, but not exclusively, stitching or various physical restraints. A mixture of fabrics can be used to form the bag. For example, the base portion of the bag can be made from nylon, and the irregular top surface can be formed from an elastic fabric. The bags 1 have a specific base shape such that the individual blocks include a uniformed and regular basal section 2, to allow regular joining and coverage of numerous blocks to cover an area (in the same way a blocked driveway could be laid for example). The depth of the basal section 2 can vary, typically between 0.1m and 1.0m, depending on the degree of protection required and velocity of the flow experienced by the protection. The seams of the fabric are joined either by sewing, with thread for example, a process of heat welding if using synthetic fabric, gluing, stud attachments, zipper, or similar. The fabric can also be tailored internally to help retain the desired shape of the basal section 2, using internal restraints and/or stiffeners made from fabric, metal or plastic to form a suitable framework.

WO 2006/037976 PCT/GB2005/003787 10 The top surface 3 of each individual block, in accordance with the invention, is irregularly shaped to resemble rock armour and provide a less artificial appearance. This may be achieved by using a stretchable fabric to form the top surface 3. A selection of restraining methods can also be utilised to allow or restrict expansion of the fabric as it is being filled with matter 5, to create an irregular surface. The fabric can be coloured with dye or a surface coating, and textured using a sand/grit type coating, which greatly improves the natural appearance of the individual blocks. The fabric forming the individual blocks incorporates valve means 4 to which a filling hose 23 can be attached, once the block is placed in location below the water surface 24 as shown in Figure 3. The valve means 4 incorporates a one way or cut off valve to prevent escape of concrete once the hose 23 has been removed and the valve is exposed to the water. Valves can be situated on the basal section 2 and/or on the top surface 3 of the individual blocks. The bags 1 are filled with matter 5 to form the blocks, as indicated by arrows 25, the matter 5 comprising grout (fine consistency), micro-concrete, regular concrete, specialist underwater concrete, sand, stones, and/or similar material. In particularly environmentally sensitive areas the attachment of the hose 23 to the bag 1 can be made out of the water to reduce the possibility of leakage from the hose 23 between filling of a number of bags below water. Additional bleed valves or outlet hoses can be included on any part of the bags to aid filling with matter and/or allow the escape of air and/or water from the bag. As shown in figure 3, the bags can include an impermeable inner layer 6, to provide better control of the matter 5 and reduce the likelihood of environmental pollution from concrete fines for example which can leak through permeable fabric.

WO 2006/037976 PCT/GB2005/003787 11 Impermeability may be achieved by application of a fabric coating such as rubber, or be an inherent property of the fabric. The fabric may be of high tenacity, or be stretchy in nature to achieve the desired effect. The use of hemp or other natural product can also be used and has the added benefit of being an environmentally more preferable material. In this example the inner layer includes a bleed valve to allow the escape of any trapped air or water from within, as voids within the concrete would otherwise weaken the concrete protection. Figures 4a-d shows an example of how the individual blocks 9 are arranged to form the scour protection system. The blocks 9 can be arranged offset in rows and/or columns as shown in Figure 4a, similar to the arrangement of bricks in a wall, or in regular rows or columns, i.e. not offset, as shown in Figure 4b. The system is assembled by interconnecting the blocks 9. As shown in Figure 4c, the use of varied sized blocks can be used to create a varied, more natural, appearance, for example using standard 1m blocks 9 with 0.5m blocks 9'. The system can be configured individually depending on the size of the scour feature, orientation of the bed and of the structure, or of the desired appearance. Referring to Figures 4a and 4d, a scour protection system is shown protecting a bridge abutment 7 from the scouring action of water flowing thereby which has resulted in a scour feature 8, in which individual blocks 9 are formed to cover the bed and prevent undermining of the abutment 7. A special edge toe detail block 10, as indicated in more detail in Figure 5, is included at the extremities of the system to reduce the possibility of undermining of the extremities of the protection by the flowing water. This edge toe detail block 10 is typically deeper than the regular blocks 9, with a significantly extended WO 2006/037976 PCT/GB2005/003787 12 base 15, such that the depth of the block typically exceeds 1m. An optional rock armour falling apron, 11, can be also included, surrounding the block protection. With reference to Figure 6, there is shown a typical arrangement of the system in section, showing how the blocks interact and work to form the protection. The individual formed fabric formwork blocks 9 protect the bed from further erosion and scour, with the edge toe detail blocks 10 forming and protecting the extremities. This system of protection protects the abutment 7 from being undermined by the scouring action of the flow of water, which has resulted in the scour feature 8. Figure 6 also shows a typical pre-scour bed profile 13, and the scoured bed profile 14 for comparison. Figures 7a-f show a range of optional connecting arrangements of the individual bags forming the blocks. The blocks can be unattached to one another, shown in Figure 7a, forming a simple butt join 16, between the individual blocks, although in reality this butt join will more closely resemble the simple butt join 16' shown on Figure 7b, due to some deformation of the bags as they are being filled, which will provide some degree of interlocking of the individual blocks. Figures 7c-d show two possible zip attachment arrangements, incorporating a zip, 17, which is formed from nylon, but can also, less suitably, be formed from metal. Figure 7e shows a possible bolt style attachment 18 including a backing plate 19 with attached bolt onto which is placed a washer 20 and nut 21. Similar configurations using butterfly or looped tie type ends 26 to a bolt fixing are possible and may be more practical as shown in Figure 7f, or possibly using flexible ties to allow a small movement due to settlement. The bolt style WO 2006/037976 PCT/GB2005/003787 13 attachment is fed through pre-formed holes within the bags and allows joining of the empty bags. The bolt arrangement would then be cast into the block as the bag is filled with concrete or other matter. Alternatively, these attachments can be used to attach any style of bag, where holes through the bags, through which the bolts are inserted, could be formed on site, during construction. A number of bags can thus be joined above water, placed, and then filled with matter a number at a time. Referring to Figure 8 there is shown a block 9 where the bag has a folded edge 22 forming a concertina or bellows effect to the fabric. By including this folded edge 22 within the fabric of the base, a regular and controllable expansion of the bag is allowed as it is being filled. This accommodates some degree of flexibility in the filling of the bags, to better accommodate irregularities in the ground profile beneath the block and allow a range of thicknesses of the block that can be created on site. It will be appreciated by persons skilled in the art that the present invention may also include further additional modifications made to the device which does not affect the overall functioning of the device.

Claims (22)

1. Scour protection apparatus comprising one or more containment means, said containment means placed in a location to prevent scour, each of said containment means substantially filled with matter to form blocks, characterised in that at least a portion of the outer surface of said containment means is adapted to have an appearance sympathetic with at least one feature of the location.

2. Scour protection apparatus according to claim 1 characterised in that the containment means are bags with a specific base shape.

3. Scour protection apparatus according to claim 2 characterised in that the bags are formed from fabric with connecting seams.

4. Scour protection apparatus according to claim 2 characterised in that the bags include one or more reinforced sections, stiffeners, and/or frame sections to help form and/or maintain the shape of the block.

5. Scour protection apparatus according to claim 2 characterised in that the bags are formed of foldable sheet material, to allow the bags to be moved between a flattened folded configuration and an erect configuration.

6. Scour protection apparatus according to claim 2 characterised in that the specific base shape is square.

7. Scour protection apparatus according to claim 1 characterised in that the matter is any or any combination WO 2006/037976 PCT/GB2005/003787 15 of grout, concrete, sand, stones and/or other aggregate material.

8. Scour protection apparatus according to claim 1 characterised in that valve means and/or filter means are provided to prevent escape of the matter placed in the containment means.

9. Scour protection apparatus according to claim 1 characterised in that a hose can be provided to connect to the containment means, to fill the same with matter and/or release trapped air, water and/or matter.

10. Scour protection apparatus according to claim 1 characterised in that the containment means is provided with an outer layer and one or more inner layers.

11. Scour protection apparatus according to claim 10 characterised in that the outer layer is permeable and one or more of the inner layers is impermeable.

12. Scour protection apparatus according to claim 1 characterised in that the system includes regular blocks and deep blocks, said deep blocks for placement around the edge of the location.

13. Scour protection apparatus according to claim 1 characterised in that the containment means are substantially filled with the matter after being placed in the location.

14. Scour protection apparatus according to claim 1 characterised in that the location is under water. WO 2006/037976 PCT/GB2005/003787 16

15. Scour protection apparatus according to claim 1 characterised in that the features are rocks.

16. Scour protection apparatus according to claim 1 characterised in that the portion is coloured and/or textured to resemble said features.

17. Scour protection apparatus according to claim 1 characterised in that the containment means is adapted by physical or mechanical impact and/or by the application of heat such that the top surface of the block has a rough irregular shape.

18. Scour protection apparatus according to claim 1 characterised in that at least a part of the containment means is formed from elasticated or deformable fabric which is adaptable such that the top surface of the block has a rough irregular shape.

19. Scour protection apparatus according to claim 1 characterised in that connection means are provided to connect adjacent containment means.

20. Scour protection apparatus comprising one or more containment means, said containment means placed in an underwater location to prevent scour, each of said containment means substantially filled with matter to form blocks, characterised in that the containment means is substantially filled with the matter after being placed at the underwater location.

21. Scour protection apparatus including at least one containment means formed by a sheet material defining a cavity into which matter is. placed to substantially fill the WO 2006/037976 PCT/GB2005/003787 17 same and characterised in that at least one surface if the containment means is adapted so as to have a higher mannings 'n' value than the remainder of the containment means' surfaces.

22. A method of providing scour protection to a location, comprising the steps of: placing containment means in a location to prevent scour; substantially filling said containment means with matter to form blocks, characterised in that at least a portion of the outer surface of said containment means is adapted to have an appearance sympathetic with at least one feature of the location.