EP0248725B1 - Method of rendering a hydraulic structure made of compacted concrete or filled earth water-tight - Google Patents

Abstract

1. Method for rendering waterproof a roller compacted concrete hydraulic structure such as a dam wherein an impermeable membrane (2) is placed on the side of said structure (1) in contact with the water, wherein said membrane (2) is made up from a staggered series of worked and assembled thick plastics material with scales (3) interlocked with each other and then welded together in a continuous way and fixed into the structure (1) by vertical fixings (11, 13) and separated from said structure (1) by a geotextile complex (4), enabling movement of the scales (3) and initiating microfissures spread regularly through the structure (1).

Description

The present invention relates to a method for making watertight a hydraulic structure in compacted concrete or in embankments with a steep upstream slope (such as a ladder wall).

For economic reasons, there is currently a tendency to carry out hydraulic works such as dams by means of compacted concrete (Roller compacted concrete). The construction of compacted concrete dams is the subject of numerous publications and in particular a communication from the ACI Committee 207 published in ACI Journal (1980, July-August, pp. 215-235).

However, it appears that the body of compacted concrete dams may have excessive water permeability, especially at the level of the recoveries between successive layers. This permeability can lead, in the long run, to an attack of the cement constituting the concrete, especially in the presence of water of an aggressive nature.

In order to remedy this drawback, various means have already been proposed for rendering the face of such works which is in contact with water impermeable.

Thus, it has been proposed (Concrete International 1964, May, p. 42), to cover this face with vertical elements of precast concrete bolted into the massif. However, the effectiveness of this technique is limited by the longevity of the fixings. In addition, this technique makes it difficult to ensure sealing of the joints, in particular of the horizontal joints.

It has also been proposed (Highway & Heavy Construction, 1985, January, p. 39), to place a layer of conventional concrete on this face. However, this concrete is subject to cracking which is increased by the absence of shrinkage joints. Given its reduced thickness, this facing is, moreover, subjected to a coloration with a strong gradient which is all the more detrimental as the water retained is aggressive.

It has also been proposed (Concrete International 1983, March, p. 21) to cover this face with a sheet of stainless steel, but such a solution turns out to be very expensive.

Finally, it has been proposed to provide this waterproofing by applying to this face a continuous membrane of reinforced butyl rubber (ibid fig. 3). The production, installation and holding in place of such a continuous membrane, however, pose serious problems and this solution has therefore been proposed only as an indication.

An economical process has now been developed for making the upstream face of such a structure watertight by mounting a membrane of impermeable plastic on this face.

The present invention therefore relates to a method for making watertight, inter alia, a hydraulic structure of compacted concrete such as a dam in which there is provided on the face of the structure in contact with water, an impermeable membrane which characterized in that said membrane is produced by staged series of plastic scales, welded together edge to edge, and anchored in the structure by vertical anchors allowing possible movement of the scales and initiating regular microcracks distributed in the structure. In the present description, the word "GEOSELLS" will be used to designate a set of worked and assembled materials, the word "tortoiseshell" being reserved for the upstream side only.

In a preferred embodiment of the method according to the invention, the edge-to-edge welds of the scales can advantageously be supplemented by thick joint covers, welded and arranged on the side of the structure.

The plastic GEOSELLS can be of any geometric shape, the rectangular shape being preferred. For practical reasons of construction, handling and installation, it is generally preferred that these scales, of rectangular shape, have a thickness of 1 to 50 mm, preferably 2 to 30 mm, a width of 2 to 8 m. , preferably 2 to 4 m, and a height of 1 to 6 m, preferably 1 to 2 m.

GEOSELLS can be made from any waterproof plastic. However, it is preferred to produce these from resins based on vinyl chloride and polyolefins. By vinyl chloride-based resins is meant polymers and copolymers containing at least 50% by weight of monomeric units derived from vinyl chloride, polyvinyl chloride being preferred. By polyolefins is meant polymers and copolymers containing at least 50% by weight of monomeric units derived from an olefin containing from 2 to 8 carbon atoms in its molecule, high density polyethylene being preferred. It is understood that the material constituting the GEOSELLS can contain usual additives such as stabilizers and in particular anti-UV agents and reinforcing agents.

In the method according to the invention, it turns out to be advantageous to provide drainage behind the impermeable membrane formed by the plastic scales. This drainage is part of the GEOSELLS.

This drainage can be ensured by vertical collectors arranged along the structure near the membrane and spaced apart, for example, from 1 to 2 m. These collectors can advantageously be produced as will be explained later, during the vertical anchoring of the scales. Preferably, each collector comes out individually in the collection gallery, which makes it possible to precisely locate any defective zone.

According to an embodiment which is preferred, this drainage is also ensured by interposing a geotextile between the structure and the membrane. Advantageously, this geotextile coats the vertical anchors of the scales which will be described later, it is included in the expression "GEOSELL".

• - désolidarisation entre la membrane et la structure dans le sens vertical ;
• - récupération des eaux ou des gaz et transit vers les collecteurs ;
• - absorption élastique des chocs éventuels sur les écailles.

The geotextile performs three advantageous functions:

• - separation between the membrane and the structure in the vertical direction;
• - recovery of water or gas and transit to collectors;
• - elastic absorption of possible shocks on the scales.

Preferably, the geotextile is fixed locally on the membrane during the implementation; it separates the scales and the anchors, after backfilling, from the mass to be sealed, and it allows the drains to be saved during possible injection by use in double thickness.

The vertical anchoring of the scales is carried out so as to leave the impermeable membrane a possibility of vertical displacement and to induce microcracks in the surface region of the structure in order to avoid the need to provide expansion joints by sawing in the structure. of compacted concrete.

According to an embodiment which is preferred, the vertical anchoring of the scales is carried out at intervals, for example, from 1 to 2 m and so as to ensure, at the same time, the formation of vertical drainage collectors.

To this end, and according to a first advantageous embodiment, the vertical anchoring is ensured by means of plates welded orthogonally and vertically on the face of the scales facing the structure, said plates being inserted into the structure, a drainage pipe. being provided at the level of the plates (plastic tube cut in half longitudinally and fixed to the plate, perforated cylindrical profile welded to the plate, etc.). The plates extend over the entire height of the scales and the vertical anchors of the superimposed scales are made in such a way that the pipes constitute vertical collectors for continuous drainage. This embodiment also has the advantage of promoting the initiation of the desired microcracking in a uniformly distributed manner.

The tubular profiles can advantageously be equipped with a profile with a cutting edge on their generatrix opposite the orthogonal bands so as to promote microcracking, this blade also entering the name "GEOSELL".

In addition, it is advantageous to provide, at the level of the plates, a tube allowing the injection of an area having defects. The width of the plates is generally from 100 to 500 mm and preferably from 200 to 400 mm.

The constituent elements of the vertical anchors are preferably made of a material identical to that constituting the scales, so as to favor their prior positioning on the scales, for example by welding.

The geotextile interposed between the scales and the structure must surround the vertical anchors and this, according to a thickness and an identical system (geotextile complex) in order to avoid, at compression due to upstream water or impacts, any risk of concentration. constraints.

The scales constituting the membrane are preferably also held in place by horizontal anchors constituted by at least one tab welded horizontally opposite the structure and forming an integral part of the GEOSELL, said tab being sealed in the structure works in shearing so as to regain the weight of the GEOSELLS. In general, the legs are placed away from the anchoring tube, which can then serve as stiffening reinforcement for the GEOSELL.

The face of the GEOSELLS in contact with water can advantageously be protected by a layer of resin concrete (30 to 60 mm thick) so as in particular to reinforce their resistance to impacts which may be, for example, caused by bodies floating. According to an advantageous process and when the constituent material allows it (for example with high density polyethylene), pebbles or tiles or even wood are laid hot (followed by cooling), which promotes local melting of the support. , hence a partial incorporation. Such integrated protection is part of the GEOSELL and completes it in aesthetic value as well as protection against ultraviolet rays (UV).

During the production of the membrane in accordance with the process according to the invention, the GEOSELLS are put in place as the structure stretches and can advantageously serve as lost formwork. Preferably, the GEOSELLS are arranged as climbing formwork-type supports, anchored in the structure through the lower GEOSELLS already in place, with the help of expansion tools called here "GEOTOOLS". These tools, according to this advantageous process, do not exist on the market. They are of the expansion type and penetrate into each GEOSELLS tube, favoring a blocking then a centering and finally allowing the adjustment of the positioning of the new GEOSELL thus creating the waterproof structure which is the subject of the present invention.

• - la figure 1 est une vue partielle, en perspective, d'une structure en béton compacté équipée d'une membrane imperméable obtenue conformément au procédé selon l'invention, assemblage en multipla- ques par haute fréquence ou par induction, avec incorporation de grillage métallique ou PVC, ou par tout autre procédé de soudure ou même de collage suivant les matériaux constitutifs ;
• - la figure 2 est une vue agrandie de la partie A de la figure 1 ;
• - la figure 3 est une vue agrandie de la partie B de la figure 1 ;
• - la figure 4 est une vue d'ensemble de réalisation pour la partie B de la figure 1 ;
• - la figure 5 est une vue de principe de l'outil "GEOTOOL" comportant une coupe horizontale du système came-expansion ;
• - la figure 6 est un exemple d'application de la structure permettant de voir la mise en place selon un procédé différent en radier et applicable en galeries ou ailleurs (murs de soutènement ou de constructions...).

To allow the continuous placement of the scales and the backfill in compacted concrete, it is possible either to backfill by zones by finishing the layers as a whistle, or to backfill continuously but with a slight slope. The overlaps between layers are no longer a real problem as soon as the upstream mask is waterproof and it has an immense associated draining capacity. This is a powerful advantage associated with this new process. The resumes will therefore have more of a mechanical nature (possible and random dropouts) than a character of continuity, moreover usually imposed, as is also the case of sealing. The process according to the invention is further illustrated by the figures of the appended drawings given purely by way of illustration and in which:

• - Figure 1 is a partial perspective view of a compacted concrete structure equipped with an impermeable membrane obtained in accordance with the method according to the invention, assembly in batches by high frequency or by induction, with incorporation of mesh metallic or PVC, or by any other welding or even bonding process depending on the constituent materials;
• - Figure 2 is an enlarged view of part A of Figure 1;
• - Figure 3 is an enlarged view of part B of Figure 1;
• - Figure 4 is an overall embodiment for part B of Figure 1;
• - Figure 5 is a principle view of the tool "GEOTOOL" comprising a horizontal section of the cam-expansion system;
• - Figure 6 is an example of application of the structure to see the establishment by a different process to write off and applicable in galleries or elsewhere (retaining walls or buildings ...).

As it appears in FIG. 1, the structure 1 of compacted concrete is coated on its face in contact with water with an impermeable membrane 2 constituted by series of GEOSELLS in plastic material with the interposition of a geotextile 4. As it appears more particularly in FIG. 2, the GEOSELLS are fixed to each other by continuous welds 5 on thick joint covers 6, welded in the workshop either by penetrating heating tip 7, or by high frequency welding heating an inclusion metallic or PVC 8.

Still on FIG. 2, one can see pebble inclusions 9. The horizontal anchoring of the GEOSELLS is carried out by the stiffening tabs 10 placed at the head of the cheeks 11 equipped with the anchoring holes 12 and securing the tube 13 with the membrane 2.

A cuff tube for possible injections can be placed at 14 and benefit from a double thickness protective bonding 15 of the geotextile complex 4. According to an embodiment illustrated in FIGS. 1 and 4, the vertical anchoring of the GEOSELLS 3 is ensured by tubular sections 13 ensuring drainage and fixed vertically on the scales 2 by strips 11 orthogonal to the scales 2. The fastenings between the scales 2, the strips 11 and the tubular sections 13 are provided by welding. The tubular sections 13 and the strips 11 are inserted into the structure 1 when it is put in place. The geotextile 4 completely surrounds the vertical anchors so as to ensure a partial separation between the structure 1 and the membrane formed by the scales 2. Profiles with a sharp edge 16 are fixed by clipping onto the ends of the vertical anchors surrounded by the geotextile 4. During the installation of successive GEOSELLS, it is also advisable to ensure the alignment of the tubular profiles 13 between the superimposed GEOSELLS so as to constitute vertical drainage collectors.

The alignment of the tubular sections 13 is carried out at the same time as the installation of successive GEOSELLS since the GEOTOOL tool 20 illustrated in FIG. 5 allows centering of continuity at the same time as the blocking in the lower part already in place. These actions are carried out from the tubular body 17 and the expansion shoe 18 allowing the centering on the recovery and anchoring of the order of 1 m inside the structure 1 in place. The expansion is carried out by half-turn of an axis carrying two cams 19, a return spring system 23 allows the tool to be removed after stabilization of the embankment making GEOSELL captive. Drainage slots 21 are produced by sawing and have a capacity calculated as a function of the immense capacities of the tube 13. In the upper part of the GEOTOOL 20, a system of two screws 22 allows the adjustment of the new GEOSELL set up. The holes 12 left in the cheeks 11 allow, in addition to handling or various hooking, to achieve using plastic tubes easy anchors for grids called "GEOGRILLES", when using embankments reinforced by GEOGRILLES. The use of GEOGRILLES for any backfill can be imposed on the surface to avoid any crack initiation.

According to Figure 6, it is advantageous to reduce the footprint of a structure by stiffening the slopes while leaving freedom to the waterproof structure. It is likewise advantageous to use on flexible foundations a flexible backfill ("TEXSOL" (a registered trademark) or other backfill reinforced with GEOGRILLES) by using an anchoring tube and the holes located in the cheeks 11 instead of, or with a compacted concrete structure.

• - cuvelage de patinoire (avec drainage des gaz) ;
• - revêtement interne de galeries (drainage, continuité d'étanchéité, strickler avantageux, élasticité permettant la conservation de l'étanchéité en mauvais terrains surtout...) ;
• - confection de murs anti-sismiques, pour maisons ou immeubles, en continuité soudée et avec remplissage léger (polyuréthanne expansé ou béton léger ...) ;
• - murs de soutènement (aspect habillé et drainage) ;
• - construction de piscines avec habillage carrelé posé en usine à chaud sur les GEOSELLS (intégré aux GEOSELLS) ;
• - remise en état de parements amont de barrages.

There are other specific examples of use of the method according to the invention, and which are numerous, such as:

• - skating rink casing (with gas drainage);
• - internal lining of galleries (drainage, continuity of waterproofing, advantageous strickler, elasticity allowing the conservation of the waterproofing in bad ground especially ...);
• - manufacture of anti-seismic walls, for houses or buildings, in welded continuity and with light filling (expanded polyurethane or light concrete ...);
• - retaining walls (dressed appearance and drainage);
• - construction of swimming pools with tiled cover placed in a hot factory on the GEOSELLS (integrated into the GEOSELLS);
• - restoration of upstream facing of dams.

Claims (15)

1. Method for rendering waterproof a roller compacted concrete hydraulic structure such as a dam wherein an impermeable membrane (2) is placed on the side of said structure (1) in contact with the water, wherein said membrane (2) is made up from a staggered series of worked and assembled thick plastics material with scales (3) interlocked with each other and then welded together in a continuous way and fixed into the structure (1) by vertical fixings (11, 13) and separated from said structure (1) by a geotextile complex (4), enabling movement of the scales (3) and initiating microfissures spread regularly through the structure (1).

2. Method according to claim 1, wherein said plastics material is 1 to 50 mm thick, preferably 2 to 30 mm.

3. Method according to claim 1 or 2, wherein the assemblies with scales (3) are welded together on the inside meaning the side facing said structure (1) on a thick support after having been interlocked in a continuous way.

4. Method according to claim 1, 2 or 3, wherein the assemblies with scales (3) are made from a high elastic resistance polyolefin or from any other similar product that is resistant to fatigue and wherein the weldings (5 or 7) can be obtained by a high frequency process which heats a metallic or polyvinylchloride inclusion (8).

5. Method according to anyone of claims 1 to 4, wherein a thick continuous and draining complex comprising a geotextile (4) and separating the membrane (2) from the structure (1) is disposed.

6. Method according to anyone of claims 1 to 5, wherein the membrane (2) is further fixed horizontally by at least one lug (10) welded horizontally to the top of each strip (11) of each assembly with scales (3), said lug (10) being embedded in said structure (1) and functioning in relative shear.

7. Method according to anyone of claims 1 to 6, wherein said membrane (2) is fixed vertically by tubular draining members (13) fixed vertically to the side of the assemblies with scales (3) facing said structure (1) by an orthogonal strip (11).

8. Method according to claim 6, wherein said membrane (2) is fixed vertically by means of tools (20) achieving by their expanding system the locking, the centering and the adjusting of the assemblies with scales (3) to be fitted at each level.

9. Method according to claim 7, wherein a tube (14) is further provided at the level of the strips (11) to enable the injection in an area featuring defects, said tubular draining member (13) being protected from such an injection by a geotextile (4) bonded on strips (11).

10. Method according to claim 7, wherein a profile (16) with a cutting edge is disposed on the tubular profile (13) covered with geotextile (4).

11. Method according to anyone of claims 1 to 10, wherein a layer of resin concrete or another coating such as hot grids or optionally tiles or even wood is applied to the side of the membrane (2) in contact with the water.

12. Method according to anyone of claims 1 to 11, wherein said assemblies with scales (3) are fitted in layers as the structure (1) is built-up and are used as non-reuseable shuttering by means of tools (20).

13. Method according to anyone of claims 1 to 12, wherein said structure (1) may be a rubble stiffened by a binder other than cement or its derivatives (roller compacted concrete) such as resins or even textiles creating a structure that can be better adapted to flexible foundations, and wherein said rubble may be also reinforced by grids.

14. Method according to anyone of claims 1 to 5, wherein the fixing disclosed in claim 6 or 7 may be replaced, in the case of foundation slaps, walls or galleries, by a continuous draining tube in an horizontal or even curved arrangement without entailing the use of tools (20).

15. Method according to claim 14, wherein the welding for continuity (5) may be achieved on the outside of the structure (2), namely on the side in contact with the water also on thick support (6) with a cold smoothed surface.

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