FR2639379A1 - PROCESS FOR THE CONSTRUCTION OF A PERRE OF PROTECTION OF A STRUCTURE SUCH AS A BANK, A JET OR THE LIKE, AND PERRE SO OBTAINED - Google Patents

Abstract

The riprap comprises, covering the sloping 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 tunnels under -jacents collecting the filtering water and the overlying channels conveying the runoff water.

Description

Process for the construction of a protection structure for a structure

  such as a bank, a pier, or the like, and a pier thus obtained.

  The present invention relates to a method for the construction of a protection structure of a structure such as a

bank, pier or whatever.

  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

  as well as this by a reinforcement embankment.

  The structure thus formed generally withstands the stresses to which it is subjected by moving water: current, waves, trunnions, tide ...

  sea water or water from rivers sensitive to 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

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 that infiltrates despite everything between the riprap and the riprap must also be able to return to the sea or the river without causing fines because this would undermine the riprap and could cause rapid deterioration of

the work and the pierced.

  Finally, it is essential that the riprap be resistant and

  rigid, be one with the foundation, be 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 one

reduced staff.

  The present invention aims to achieve this object and for this purpose, the proposed method consists, for its execution during the very short time of low water, to apply to the sloping surface of the riprap of the structure, a filter cloth leaving pass the water but not the fines and cover them with a flexible sheath with multiple conduits extending along the slope of said surface, close the conduits against the foundation and file at least the upper part of the sheath in the structure, pour concrete into the said conduits and 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

  by getting rid of low water containers.

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

  visible part of the channels carrying the flowing water.

  The method can also consist in introducing a reinforcement into each of the conduits of the sheath, providing means for keeping the latter away from the walls of the conduit.

  considered when pouring 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 fitting canvas, these coated beams delimiting between them small underlying tunnels collecting the filtering water and overlying channels conveying

runoff water.

  Advantageously, the sloping beams wrapped in concrete contain at least one reinforcement intended to be fixed to the

  minus a reinforcement element stuck in a foundation beam.

  The frames of the wrapped concrete sloping beams are provided with spacers to separate them from the wall of the

  flexible conduit enveloping said beams.

  Various other features and benefits of

  the invention will moreover emerge from the detailed description which

  follows. One embodiment of the subject of the invention is

  shown, by way of nonlimiting example, in the accompanying drawing.

  In this drawing: - Figure 1 is a cross section of a structure on which the riprap of the invention is installed, - Figure 2 is a plan view of a sheath as it can be unwound on the floor or the sloping surface of the structure, - Figure 3 is a section taken on a larger scale along line III-III of Figure 1, - Figure 4 is a view similar to Figure 2 illustrating a variant with reinforcement , Figure 5 is a partial view similar to the 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 pier is constituted in the form of an embankment with the natural terrain 5 which is covered by a riprap 6. The sloping surface 7 of the riprap which connects the circulation surface of the carriageway 2 to the bottom 8 of the river or the sea, is coated with a riprap 9 whose foot 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 embankment It intended to remove this area from the devastating action of the sea or the river. The water level on the river rises and S05 lowers with the tides and this movement of ebb and flow, is added that of waves, eddies, currents ... At low tide, the perré 9 and the foundation 10 are discovered and we only have 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 constituted by two sheets 13 and 14 connected together by parallel fixing lines. 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 it 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 in

up, closed down.

  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 solid conduits is closed by any appropriate means, such as staples, and the sheath 12 is fixed to the riprap 6 for the part filled 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 swell 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. However, as soon as

  it begins to overlap, 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 action

  particularly devastating of the sea or the covering water.

  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 book. A real protection of the work is accomplished.

  Furthermore, the beams 18 delimit between them overlying channels 21 which convey apparently and towards the

  low reflux and runoff water.

  Of course, it may be advantageous to arm the beams 18 in order to form an even better structure resistant to assault

flow and waves.

  To this end, the variant according to Figures 4 and 5 can be implemented. First of all, one or more reinforcements 22 are slid into the conduits 16 while the sheath 12 is deployed step by step either on the steep 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 can be seen from FIG. 4, the frames 22 are fitted with spacers 23 suitably spaced and perforated, before being

inserted into the conduits 16.

  In addition, it is particularly interesting to

  build the foundation 10 with a reinforced concrete beam (Figure 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 reinforcement 26

  extend through said sections. The envelopes are closed.

  This beam 10 is bristling with reinforcing elements 27 projecting above and parallel to the sloping surface 7 of the riprap 6 of the structure. The elements 27 are inserted in the wrapped sections 24 of the foundation beam 10, before the setting of the concrete and are centered on the locations which will occupy

  the lower ends of the conduits 16 of the sheath 12.

  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 conduits one

  after another. The beams thus formed are inserted.

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

beams 18.

Claims (7)

R E V E N D I C A T I 0 N S   i.- Process for the construction in low water of a riprap (10) for the protection of a structure (1) such as a bank, a pier or other, characterized in that it consists, for its execution during the very short time of low water, to apply on the sloping surface of the riprap (6) of the structure, a filter cloth (17) allowing water to pass but not the fines and to cover it with a flexible sheath (12) with multiple conduits (16) extending along the slope of said surface, closing the conduits against the foundation (10) and fitting (at 19) the upper part at least of the sheath in the structure , pouring concrete   in 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 filter 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) carrying 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 during 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) inserted in said beam and making   protrusion thereof 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 process   according to any one of claims 1 to 4 and characterized in   what it comprises, covering the sloping 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 channels   overlying (21) conveying 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 element   of reinforcement (27) plugged into a foundation beam (10).   7.- Perré according to claim 6, characterized in that the frames (22) of the sloping wrapped concrete beams (18) are provided with spacers (23) making it possible to separate them from the   wall of the flexible duct enveloping said beams.