EP0370889A1 - Method for the construction of a protection facing for works such as a slope, a bank or the like, and facing thus obtained - Google Patents

Abstract

The facing comprises, covering the sloping revetment (6) of the work (1), concrete beams (18) sheathed with flexible pipes (16) connected to one another and placed on a filtering cloth (17), these sheathed beams defining between them small underlying tunnels collecting the filtered water and channels lying on top conveying the surface water. <IMAGE>

Description

The present invention relates to a method for the construction of a protection structure for a structure such as a bank, a pier or the like.

Up to now, the perré has consisted of cut and masonry granite or alternatively stones filled with bituminous mastic. This coating is generally placed on a rockfill in various materials covering the slope formed from the natural ground. The foot of the perré abuts against the foundation and is covered like this one by a reinforcement embankment.

The structure thus formed generally withstands the stresses to which it is subjected by moving water: current, waves, trunnions, tide ... whether it is sea water or water from sensitive rivers. at the tide.

However, its repair or its construction step by step raises major difficulties. First of all, a competent workforce is no longer in sufficient quantity, the working conditions are painful and tiring, the cost of repairing is too expensive. Then and above all, it is only possible to work economically when the water is uncovered, that is to say three to four hours per tide and never at the same time, which implies a practically permanent availability of the workforce.

In addition, it is imperative that the water which flows on the perré returns to the sea or the river without staying and without deteriorating anything. In addition, the water which infiltrates despite everything between the riprap and the riprap must also be able to return to the sea or the river without entraining fines as this would undermine the riprap and could cause rapid deterioration of the structure. and perré.

Finally, it is essential that the riprap is strong and rigid, that it is one with the foundation, that it is reliable.

Of course, the execution of the pier must be fast, efficient and inexpensive. It must be able to be interrupted without damage when the water rises. It should only require a reduced number of staff.

The present invention aims to achieve this goal by implementing the teaching provided by European patent application No. 0 138 259 to produce a filter bed on a reinforced embankment embankment. The solid mass is then constituted by a sheath with multiple conduits extending along the slope and filled with an injectable material such as expanded clay granules.

In accordance with the invention and for the abovementioned purpose, the method also consists in:
- to deposit freely on the riprap before the sheath, a filter cloth (17) letting the water pass but not the fines,
- to close the conduits against the foundation (10) and to file (in 19) the upper part at least of the sheath and the canvas in the structure,
- pouring concrete into said conduits,
- and to close them when they are full.

Unconsolidated concrete thus enclosed in the sheath therefore does not risk being diluted in seawater or river water when the riprap is covered. He therefore continues to take hold of the low water containers.

Advantageously, the method consists in providing:
- between the pipes filled with concrete and the filter cloth of small tunnels collecting the water which filters through it and directing it downwards,
- and between the concrete-filled conduits on the side of their visible part of the channels carrying the flowing water.

The method can also consist in introducing into each of the conduits of the sheath a reinforcement by providing means for keeping the latter spaced from the walls of the conduit considered during the pouring of the concrete.

Furthermore, to ensure the embedding of conduits filled with reinforced concrete and a reinforced concrete foundation beam, the reinforcements of said conduits are fixed to transverse reinforcement elements inserted in said beam and projecting from this parallel to the slope.

The invention also extends to the riprap obtained by the implementation of the aforementioned process and in accordance with the invention, this riprap comprises, in recovery of the steep riprap of the structure, concrete beams coated with conduits flexible joined together and placed on a filter cloth, these coated beams delimiting between them small underlying tunnels collecting filtering water and overlying channels conveying runoff water.

Advantageously, the sloping beams wrapped in concrete contain at least one reinforcement intended to be fixed on at least one reinforcement element plugged into a foundation beam.

The reinforcements of the wrapped concrete sloping beams are provided with spacers making it possible to separate them from the wall of the flexible conduit enveloping said beams.

Various other characteristics and advantages of the invention will also emerge from the detailed description which follows.

An embodiment of the object of the invention is shown, by way of nonlimiting example, in the accompanying drawing.

• - la figure 1 est une coupe transversale d'un ouvrage sur lequel le perré de l'invention est installé,
• - la figure 2 est une vue en plan d'une gaine telle qu'elle peut être déroulée sur la chaussée ou la surface en pente de l'ouvrage,
• - la figure 3 est une coupe prise à plus grande échelle suivant la ligne III-III de la figure 1,
• - la figure 4 est une vue analogue à la figure 2 illustrant une variante avec armatures,
• - la figure 5 est une vue partielle analogue à la figure 1 montrant la mise en oeuvre de cette variante.

On this drawing :

• FIG. 1 is a cross section of a structure on which the riprap of the invention is installed,
• FIG. 2 is a plan view of a sheath such that it can be unwound on the roadway or the sloping surface of the structure,
• FIG. 3 is a section taken on a larger scale along the line III-III of FIG. 1,
• FIG. 4 is a view similar to FIG. 2 illustrating a variant with armatures,
• - Figure 5 is a partial view similar to Figure 1 showing the implementation of this variant.

As can be seen from FIG. 1, the structure to which the method of the invention applies is a pier 1 on which a pavement 2 is built, bordered at least on one side by a sidewalk 3 and a concrete parapet 4. The jetty is built in the form of an embankment with natural terrain 5 which is covered by riprap 6. The sloping surface 7 of riprap which connects the traffic surface of the carriageway 2 to bottom 8 of the river or the sea, is coated with a riprap 9, the foot of which abuts against a foundation 10. The bottom of the riprap 9, the foundation 10 and the neighboring part of the bottom 8 are covered by a reinforcing fill 11 intended to protect this area from the devastating action of the sea or the river. The water level on the river rises and falls with the tides and this movement of ebb and flow, is added that of waves, eddies, currents ... At low tide, the river 9 and the foundation 10 are discovered and there are then only three to four hours to work "dry".

As shown in Figures 1 to 3, the pierced 9 is constructed by means of a flexible sheath 12 formed by two sheets 13 and 14 connected together by fixing lines 15 parallel. The single or multiple fixing lines are, in the example chosen, seams, but can also be stapling, welding, gluing lines ... The sheets 13 and 14 are advantageously made of woven polypropylene fabric.

Anyway, the sheath 12 delimits parallel conduits 16 and is spread over a filter cloth 17 covering the sloping surface 7 of the riprap of the structure so that said conduits extend along the slope and are open at the top , closed at the bottom.

The lower edge of the sheath 12 can be sewn to close the lower end of the conduits 16 and the latter is brought to abut against the foundation 10, while the said sheath is laid flat and freely on the filter cloth 17 fixed to the riprap 6.

During the formation of the riprap, certain conduits 16 are filled with concrete 18 and follow the shape of the riprap through the filter cloth 17. The upper end of the conduits full is closed by any suitable means, such as staples, and the sheath 12 is fixed on the riprap 6 for the filled part only by means of plugs 19 planted at the head (FIG. 1) and possibly on the sides.

The first empty duct which presents itself is free to inflate and deform; its upper mouth can then be opened to introduce the pipe of a concrete pump and the filling of the conduit with concrete can be carried out; the mouth is closed and fixing cards 19 are planted. This filling method progresses step by step and the riprap is thus formed by "molding" on the riprap.

Construction work can be continued as long as the sea or river remains low. By cons, as soon as it begins to cover, it is necessary to interrupt said work. However, the sloping beams 18 of concrete not yet set and not consolidated, are protected by the sheath 12 and withdrawn from the particularly devastating action of the sea or the water which covers.

At the next tide, work resumes and as time passes, the beams 18 consolidate and form a solid and resistant structure.

As can be seen from FIG. 3, the beams 18 delimit between them tunnels collecting the water which re-emerges from the riprap 6 and crosses the filter cloth 17, which opposes the passage of fines and prevents degradation of the work. True protection of the structure is accomplished.

Furthermore, the beams 18 delimit between them overlying channels 21 which apparently and downwardly convey the reflux and runoff water.

Of course, it may be advantageous to arm the beams 18 in order to form a structure which is even better resistant to the onslaught of the flow and the waves.

To this end, the variant according to Figures 4 and 5 can be implemented. First, one or more frames 22 are slid into the conduits 16 while the sheath 12 is deployed step by step either on the sloping surface 7 of the riprap, or on the roadway 2 before it is placed on said surface.

In order for the reinforcements 22 to extend within the concrete, various means can be used. For example, and as is apparent from FIG. 4, the frames 22 are fitted with spacers 23 suitably spaced and perforated, before being inserted into the conduits 16.

Furthermore, it is particularly advantageous to constitute the foundation 10 by a reinforced concrete beam (FIG. 5). The latter then comprises a plurality of aligned sections of concrete 24, filling flexible envelopes 25 and placed under pressure against one another. Longitudinal reinforcements 26 extend through said sections. The envelopes are closed.

This beam 10 is bristling with reinforcing elements 27 protruding above and parallel to the sloping surface 7 of the riprap 6 of the structure. The elements 27 are inserted into the wrapped sections 24 of the foundation beam 10, before setting the concrete and are centered on the locations which the lower ends of the conduits 16 of the sheath 12 will occupy.

During the installation of this sheath, the lower edge of the latter is disjointed in the center of each conduit to exit from the conduit considered the armature 22 and connect it by a ligature or staples 28 to the corresponding element 27. Then, all the conduits are re-threaded on the reinforcement thus joined. The sheath is stretched upwards. Concrete is poured into the conduits one after the other. The beams thus formed are inserted.

When the riprap is finished, a fitting 29 (FIG. 1) is placed between the parapet 4 and the upper ends of the beams 18.

Claims (7)

1.- Method for the construction in low water of a riprap (10) for the protection of a work (1) such as a bank, a pier or other, consisting, for its execution during the very short time of low water , to cover the sloping surface of the riprap (6) of the structure, with a flexible sheath (12) delimiting multiple conduits (16) extending along the slope of said surface and intended to contain a material of filling,
characterized in that it also consists:
- to deposit freely on the riprap before the sheath, a filter cloth (17) letting the water pass but not the fines,
- to close the conduits against the foundation (10) and to file (in 19) the upper part at least of the sheath and the canvas in the structure,
- pouring concrete into said conduits,
- and to close them when they are full. 2.- Method according to claim 1, characterized in that it consists in providing:
- between the conduits (16) filled with concrete (18) and the filter cloth (17) of small tunnels (20) collecting the water which filters through it and directing it downwards,
- And between the conduits (16) filled with concrete (18) on the side of their visible part of the channels (21) conveying the flowing water. 3.- Method according to claim 1 or 2, characterized in that it consists in introducing into each of the ducts of the sheath a frame (22) by providing means (23) to keep it spaced from the walls of the duct considered when pouring concrete. 4.- Method according to claim 3, characterized in that to ensure the embedding of the conduits (16) filled with reinforced concrete (18) and a foundation beam (10) in reinforced concrete, the reinforcements (22) of said conduits are fixed to transverse reinforcing elements (27) plugged into said beam and projecting therefrom parallel to the slope. 5.- Perré for the protection of a structure such as a bank, a pier or other obtained by the implementation of the method according to any one of claims 1 to 4 and characterized in that it comprises, in overlap of the steep riprap (6) of the structure (1), concrete beams (18) coated by flexible conduits (16) joined together and placed on a filter cloth (17), these coated beams delimiting between them small underlying tunnels (20) collecting the filtering water and overlying channels (21) carrying the runoff water. 6.- Perré according to claim 5, characterized in that the sloping beams wrapped in concrete (18) contain at least one frame (22) intended to be fixed on at least one frame element (27) inserted in a beam of foundation (10). 7.- Perré according to claim 6, characterized in that the frames (22) of the wrapped concrete sloping beams (18) are provided with spacers (23) making it possible to separate them from the wall of the flexible conduit enveloping said beams.

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