Abstract:
A pair of webs each extending over a large area and disposed in a vertical orientation in a suspension are interconnected by a pair of telescoping tubes attached to juxtaposed edges of the respective barrier webs. Material of the suspension is removed from the space within the inner tube to provide a hydraulic trap for liquid entering the connection or coupling between the two tubes. A device is provided for inspecting the level of the liquid collected in the hydraulic trap or for removing the collected liquid. The barrier webs are advantageously made of synthetic resin material such as high-density polyethylene.

Description:
BACKGROUND OF THE INVENTION 
     The invention relates to a plug connection for planar barrier webs. 
     Large-area sealing measures in foundation and hydraulic engineering, as well as for encapsulating contaminated locations such as depositories and the like, must comprise, as a rule, sections with finite dimensions if foils, plates or membranes are used. The connection of these sections to each other should be so tight that no appreciable effect on the barrier action occurs at the connecting points. If flat barrier layers of foils, plates or membranes are built-in horizontally, the connection is usually made by welding or cementing at the overlap edges. In contrast, the preparation of vertical barrier layers generally necessitates a production method in which the foils or plates or membranes are placed section by section in a slot filled with suspension. For this method of fabrication, no connection elements are known which assure a reliable and controllable barrier action at the connection point. 
     It is therefore an object of the invention to provide a device for connecting large-area barrier layers which are positioned section by section in suspension-filled slots, which device is reliably tight and has a sealing action which remains controllable for a long term after fabrication is completed. 
     SUMMARY OF THE INVENTION 
     A plug connection according to the present invention comprises telescoping tubes which are rigidly attached to the edges of the respective barrier layer sections to be connected. After the tubes are pushed together, the interior of the plug connection is cleaned out. Possible circulation of liquids in the space between the slotted outer tube of the plug connection and the inner plug-in pipe is interrupted by openings into the interior of the inner pipe so that the cleaned-out interior acts as a &#34;hydraulic trap&#34; for liquids that may have penetrated. By level measurements or drawing-off of the liquids which have entered the interior of the inner pipe, the barrier action of the plug connection can be controlled for a long time after construction is completed. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     FIG. 1 is a transverse cross section through a plug connection in accordance with the invention. 
     FIG. 2 is a transverse section through a sealing assembly with a plug connection according to the invention. 
     FIG. 3 is a schematic longitudinal section through a sealing assembly at a depository. 
     FIG. 4 is a schematic longitudinal section through a plug connection in accordance with the invention. 
     FIG. 5 is a transverse section through another plug connection in accordance with the invention. 
     FIG. 6 is a transverse section through another plug connection pursuant to the present invention. 
     FIG. 7 is a transverse section through a yet another plug connection pursuant to the present invention. 
     FIG. 8 is a transverse section through a further plug connection in accordance with the invention. 
    
    
     DETAILED DESCRIPTION 
     At juxtaposed edges of a pair of large-area barrier webs in the form of foils, plates or membrane sections 1.1 and 1.2, as shown in FIG. 1, a slotted outer tube 2 and an inner plug-in tube 3 are arranged tightly and continuously one within the other. In the particular embodiment shown here, the edge of barrier web 1.1 is welded to a slot in outer tube 2 and the edge of barrier web 1.2 in the inner plug-in tube 3. These connecting seams 15 can be fabricated, however, without a slot or by cementing. The inside diameter of the slotted outer tube 2 is larger than or equal to the outside diameter of the inner plug-in tube 3. As a rule, the outside diameter of the inner plug-in tube 3 is larger than slot 6 in the slotted outer tube 2, so that a forced guidance of the inner plug-in tube 3 is provided when the inner plug-in tube 3 is inserted into the slotted outer tube 2. Positioning the barrier layer section 1.2 with the inner plug-in tube 3 takes place in the suspension 5 of the slot. A space 16 between the inner plug-in tube 3 and the slotted outer tube 2 and an interior space within inner plug-in tube 3 is filled initially with the material of suspension 5. After a certain degree of initial hardening of the material of suspension 5, interior space 4 is cleaned out. This cleaning out can be accomplished by, for instance, high-pressure water jets and pumping-off. In the inner plug-in tube 3, openings 7 are provided opposite the respective connecting seam 15. If a liquid 14 in suspension 5 penetrates through slot 6 into space 16, this liquid 14 is conducted through openings 7 into interior space 4 and is thereby prevented from further circulation in space 16. The interior space 4 and its openings 7 to space 16 thus act as a &#34;hydraulic trap&#34; for liquids 14 which may have penetrated into space 16. 
     FIG. 2 shows in schematic cross section a vertical sealing barrier formed of webs 1.1, 1.2 and 1.3. Into a slot filled with suspension 5 and defined by wall boundaries 8.1 and 8.2, barrier webs, foils, plates or membrane sections 1.1, 1.2 and 1.3 are placed. The sections 1.1, 1.2 and 1.3 are connected to one another via plug connections according to the invention. Each plug connection includes slotted outer tube 2 and inner plug tube 3 as well as cleaned-out interior 4. 
     To prevent seepage water from a depository body 9 illustrated schematically in FIG. 3 from escaping, a vertical sealing wall is disposed in the vicinity of permeable soil layers 11, which wall leads to an impermeable soil horizon or layer 10. The vertical sealing wall comprises a slot which is defined by boundaries 8.1 and 8.2 and is filled with a hardening suspension 5. A barrier 1 of at least one layer of webs, foils, plates or membranes is disposed in the suspension. In the interior space 4 of the plug connection shown in FIG. 3 is disposed a device 12 for taking off liquid or for leveling out the liquid level in the interior space. 
     In an embodiment of the invention shown in FIG. 4, the lower end of the inner plug tube 3 is closed off by a bottom plate 13. Liquid 14 which has penetrated into intertube space 16 is conducted via openings 7 into interior space 4 of inner plug tube 3 and is collected there. The collected liquid 14 can be suctioned off and/or leveled out via a device 12, including a pipe and, for depths greater than 8 m, a pump (not shown). Inner plug tube 3 is surrounded by slotted outer tube 2. To tubes 2 and 3 are attached the respectively adjacent barrier layer sections 1.1 and 1.2. 
     In an advantageous embodiment of the invention shown in FIG. 5, the inside diameter of slotted outer tube 2 is equal to the outside diameter of the inner plug tube 3 so that an accurately fitting seat is provided. A first advantage of this design is the direct sealing surface between the inner plug tube 3 and the slotted outer tube 2. A further advantage is the geometrical, unambiguous boundary of interior space 4 when the latter is flushed out, so that no material of suspension 5 can follow through space 16. This makes an evacuation of space 4 possible even if the suspension is not of a hardening type. 
     FIG. 6 shows the plug connection comprising inner plug tube 3 and slotted outer tube 2. Before inner plug tube 3 is put in place in outer tube 2, a hose 17 is placed in interior space 4 and is filled with air or advantageously with a liquid, so that interior space 4 is completely filled and no material of suspension 5 can enter. After the connection is made, the hose is emptied and removed and interior space 4 is cleaned out. To enhance the barrier effect, space 16 can additionally be filled under pressure with a suitable sealing compound 18. 
     FIG. 7 shows inner plug tube 3 provided with longitudinal beads which engage the inside surface of slotted outer tube 2. These sealing beads 19 have such a height or depth that a certain contact pressure is preserved over the long term. A space 16.1 outside the sealing beads is filled with suspension 5. An inner space 16.2 is flushed out together with interior space 4 and openings 7. If the sealing beads are permeable, liquid 14 which has passed through the beads is collected in interior space 4 and discharged from there in accordance with the invention. 
     As illustrated in FIG. 8, as an alternative to sealing beads 19, sealing profiles of rubber-elastic materials 25 may be either slipped-in or advantageously fastened, cemented or welded in slots or directly on the surface of inner plug tube 3. 
     The materials for laminar barrier webs or sections 1.1, 1.2 and 1.3 and the connecting elements are a preferably plastic and advantageously high-density polyethylene (HDPE). The geometric dimensions are variable. In an advantageous design, the following dimensions are conceivable: the thickness of the barrier webs 1.1, 1.2 and 1.3 is 1 to 10 mm; the wall thickness of slotted outer tube 2 and inner plug tube 3 is 5 to 20 mm; the mean diameter of inner plug tube 3 is 50 to 200 mm; the mean diameter of slotted outer tube 2 is 70 to 250 mm; width of slot 6 is 10 to 50 mm and of openings 7 is 6 to 30 mm; and the thickness of space 16 is 0 to 20 mm.