FR2492864A1 - Water-stop sheets assembled using twin sliding fastener tracks - to positively seal large and/or deep construction faces - Google Patents

Abstract

Modular sheets for use as waterstop linings are made as long strips having pairs of sliding clasp fastener tracks welded onto each border and suitable for linking adjacent strips to seal a wider area. Opt. the seal is ensured by subsequent introduction of an adhesive or a hot gas into the local cavity between each pair of tracks. Opt. the sealed fasteners are consolidated during sequential lay-up in situ by applying pneumatic or hydraulic back pressure from a local pressure tube backed by a suitable steel profile, and opt. covered with a layer of clay, bentonite and/or cement. The strips may be of polyolefin, PVC, polyamide or polyester film or sheet. Applicable to vertical, sloping or horizontal faces on dam walls, canal basins, major plant cooling systems, fuel storage tanks etc.

Description

 The present invention relates to watertight cuts of gran of dimension in the basement under the phreatic nsppe such as for example the cores or dams of dams or the watertightness ithos of channels or tanks. If the invention is especially designed for vertical screens, the product used can be used for horizontal screens with even more ease of application.

At present, the majority of vertical screens are made by digging with a dumpster a continuous wall whose dimensions range from several meters to several tens of meters in depth and from several tens to several hundred meters in length. this trench is sealed using clay, bentonite or cement, or finally a mixture of the three
Because of the iragility of these walls or of their too great flexibility, the risks of discontinuity or their lack of tightness, finally of the raw materials, many people have thought of reinforcing them with a waterproof plastic membrane. Unfortunately, this always comes in the form of rolls of finite dimensions out of proportion to those of the trench.
Soldering or gluing them underwater is not easy, assembling them on the surface to lower them in one go is very delicate. Most of the existing patents actually concern the different ways of partially superimposing the leaves but without ensuring a real connection, both mechanical and waterproof0
D'invention proposes a means of restoring continuity by a stapling system possibly supplemented by a hot or cold bonding in situ. It also offers a very economical implementation process.

 The basic products are rolls of plastic films of the polyethylene, polyvinylchloride, polypropilene, nylon, polyester type and, in general, of any current or future heat-sealable material. The previous list is presented in order of increasing tensile strength. final choice will depend on this resistance but also on other characteristics such as the resistance after welding price ratio, tear resistance on stones, adhesion of adhesives, chemical resistance, resistance to bacteria and rodents.

The width of the rollers will be as large as possible.
and others of these rollers are welded in the factory along the length of the
tape a plastic zipper such as those existing on the market and generally used for closing plastic bags. If the tightness of these closures is insufficient, a water resistance to 20 meters may be required, welded then a second closure on or next to the previous one so that after stapling two neighboring films there remains a small central channel as shown in Figure I. In this channel will be injected after backfilling either a cold glue or a current of hot air which will cause a start of heat sealing of the two lips of the closure.

 The assembly of these films under a fluid is relatively easy. For a vertical trench, for example perforated with a retaining fluid of the clay, bentonite or mud type.

with bentonite-cement, we successively unroll the rollers horizontally from top to bottom and side by side, then we assemble them using the appropriate slider after having ballasted them. In the simplest method but also the most incubating the rest of the trench will be filled with a cement bentonite grout which will perfect the watertightness of the slides and the film in general.

 We will, however, describe with the help of Figure 2 a process which allows backfilling with less costly materials than cement grouts and in particular using cuttings in progress. We understand that the difficulty of this backfilling the help of solid materials is to avoid that in their fall and their installation they tear, deform or unclip the membranes in place. In addition it cannot be tolerated in the trench an angle of slope of the embankments which would come hinder the installation of new membranes and the perforation in progress.

 There is therefore a double necessity, that of compartmentalizing the cleaning and that of protecting and securing the films as best as possible during this operation.

 FIG. 2 shows the phasing of the operations In zone I the perforatin is in progress under bentonite mud at the wing of a clamshell machine or any other equivalent machine. In zone 2 a new roll fitted with its closure is unrolled in the trench at the edge of the previous one already in small plots two films are then stapled under the mud using a weighted slider.

To fix the ideas, this zone 2 is located at least 5 meters from zone I in order to prevent blocks and waves from the bucket from disturbing the installation. We also have an interest in ballasting the film in the bottom as long as it has not been pressed against the ground by a partitioning cheek.These cheeks are constituted by metallic profiles ootportzat two-heels. One enters the ground and pockets the sliding of the profile under 11 influence the other is provided with an inflatable sleeve which is pressed against the membrane. In sDne 9 we can see how these two sections are fairly efficient in dividing up the embankments and temporarily maintaining the membrane. When backfilling the area 3 is finished the cheek placed last is left in place and the other is extracted, after deflating the sleeve, as if it were the extraction of a sheet pile. We can see that the shape given to the profiles pockets these come to fret against the membrane when extraction.

The profile thus recovered is then lowered into zone 2 to come and press the last film put in place against the ground.

 In the case where the embankments are dangerous in nature for the membrane either because of their shape or because of the low resistance of the membrane, it will be possible to protect the latter by a cover, not shown in the figure, and which may further for example a very resistant roll of synthetic woven fabric which will be recovered as the embankment rises.

 In the finished zone 4 the void left by the profiles is filled all by itself by a slight compaction of the backfill but without causing significant slip harmful to the membrane due to the small volume of the profiles. or welding the slide fasteners through the central channel as described above.

 Finally, the backfill can also be completed by filling with cement grout in the interstitial spaces. This is not, however, an obligation since it may be advantageous in certain applications for the backfill to be draining.

For the use of these membranes as a cover mat on horizontal or inclined bottoms such as channel beds or dams, the installation method is obvious.
The rollers are deployed underwater edge to edge, a diver or even a simple boat using a cable comes to slide the cursor in the slides and it only remains to protect the membrane by an embankment.

Claims (4)

 I. Semi-finished product of the plastic film roll type with factory manufacturing dimeneions and characterized by the fact that it has been provided by heat-sealing, along the length of the two longitudinal edges of the fastening zippers, continuous and in plastic material, with the sole aim of being able to reconstitute, by edge-to-edge stapling of different strips, a waterproof, flat membrane, of larger size and of definitive character  2.Product according to claim I characterized in that each edge of the strip is provided with at least two sidereal glue closures superimposed or slightly offset so that after stapling with another strip there remains between the two closures a small sheath intended to allow perfect sealing of closures by injection of glue or hot gas0  3.Uses of the product of claims I and 2 in public works to constitute dee sealed vertical cuts in large continuous trenches, or sealing mats at the bottom of canals, dams and various reservoirs, of water drinking water, cooling power stations, chemicals such as petroleum, and finally in a general way wherever the usual means of reconstituting large waterproof membranes are difficult to implement.  4. Means for the implementation, in a vertical trench, of the product of claim I or 2, characterized by the fact that after placement of the strips from top to bottom in the trench and stapling edge to edge, a profile metal plate presses the membrane against the ground using an inflatable sleeve and delimits a compartment allowing backfilling with solid materials.