EP0450154B1 - Use of a protecting element for the protection of sealing layers in landfills, and a method for sealing landfills. - Google Patents

Abstract

A protection course for sealing layers in landfills is to be capable of being produced quickly and is to guarantee reliable protection even on slopes. To this end, a protection element (1, 15, 21, 33) is proposed according to the invention. The protection element (1, 15, 21, 33) is designed as a flat container of essentially uniform height which contains a filling of sand (10, 36) or sand-like bulk material and extends in such a way that a large proportion of it can be laid in a continuous bond to form a protection course. <IMAGE>

Description

The invention relates to the use of a protective element for protecting sealing membranes in landfill construction and to a method for producing a protective layer

When building landfills, it must be ensured that the landfill floor is absolutely tight. In the prior art, this is achieved in that a mineral base seal and a polymeric sealing membrane is placed on the existing floor, the sealing membrane consisting of sealing membranes laid next to one another, which are sealed together at their film edges. So that the sealing membrane does not suffer any mechanical damage from the material lying above it, in particular not being perforated, it is known in the prior art to apply protective elements to the sealing layer before a gravel layer is then installed as a surface drainage in the grain size 16/32 mm.

Protective elements are known which are designed as a composite material and consist of a carrier fabric with high strength and punch penetration force and a nonwoven fabric needled thereon. So they form a needle felt with high-strength carrier fabric and are placed on the sealing membrane with the fabric side up. They are used to carry and bear part of the loads that occur to distribute. As a rule, however, a 10̸ cm thick protective layer of sand must then be heaped up.

However, a layer of sand is still an ideal protection against damage to the waterproofing membrane due to the layer of gravel to be applied and the garbage. However, the installation of the protective layer made of sand causes considerable problems, since the use of construction machinery is not possible due to the risk of damage to the sealing layer, but on the other hand the installation with a wheelbarrow and shovel is too expensive. In addition, this installation by hand does not guarantee that the desired minimum thickness is present everywhere, so that, for safety's sake, more sand is applied than is necessary for the protective effect. In addition, the layer of sand is displaced by the people entering it and their footprints in such a way that the thickness is too small in places. There are also problems with keeping the sand in the necessary thickness on the sloping side slopes of the landfill pit. In many cases it slips, so that the protection of the waterproofing membrane on the embankments is insufficient.

From BE-A-560̸ 165 a protective element for use in hydraulic engineering is known, with which the unprotected bottom of a body of water is to be protected against the action of the flow forces in such a way that washing away of the soil material is prevented. The protective element is designed as a closed sack with limp walls and contains a filling made of sand-like material. Distance limiters ensure that the sack has a substantially constant height.

The invention has for its object to provide a protective layer made using sand-like bulk material for the protection of waterproofing membranes in landfill construction, which can be produced quickly and which ensures reliable protection against damage to the waterproofing membrane even on embankments.

According to the invention, this object is achieved by the use of a protective element designed as a flat container with a substantially constant height, in which a filling of sand or a sand-like bulk material is filled and which has such an extent that a large number of it can be laid in a seamless bond to form a protective layer , solved to protect waterproofing membranes in landfill construction.

The use of the protective element according to the invention is characterized by enormous advantages. The protective element can be quickly and easily laid to form a protective layer by laying out the protective elements next to one another in a seamless connection. The size of the protective elements should be such that they can be carried by one or a maximum of two people. In particular if the flat container is designed to be closed on the top, no changes in the thickness of the sand layer are brought about by entering the person who is laying out the protective elements. In this way, the sand layer has the same thickness everywhere, so that the height of the sand layer and thus the protective element can also be reduced to the level that is just required, which leads to lower material consumption. The protective element has particular advantages when covering embankments, since the sand cannot slide off. The same thickness of sand layer is also guaranteed there.

As tests have shown, by using the protective element according to the invention, the height of the sand layer can be increased get along, which is much less than piled-up layers of sand. An excellent protective effect is achieved with heights of less than 5 cm, even with a height of 2 cm.

In an embodiment of the basic idea of the invention, it is provided that the flat container is a closed, preferably completely filled sack with limp walls. A flat container designed in this way can be produced simply and inexpensively from various materials. Spacers should be distributed over the interior of the sack, for example in the form of limiting tapes, so that the sack does not change its flat shape during filling and also during subsequent transport, i. H. not dented. Correspondingly tear-resistant films are suitable as materials. The sacks are particularly suitable if the walls consist of a textile material which is impermeable to the filling, for example a woven or knitted fabric, in particular a Raschel fabric. Their threads should consist of polypropylene (PP) or high density polyethylene (HDPE) or a mixture thereof, since these plastics are particularly resistant. It has proven to be favorable for the dimensional stability of the flat containers made of textile material if the textile material is provided with a stabilizing coating, for example made of polyethylene (PE), in particular LLDPE or HDPE. This avoids the tendency of textile material to stretch and thread displacements and improves the sealing against the filling material. In addition, the walls become relatively impermeable, as a result of which flushing out of the filling material is avoided.

The spacer tapes are expediently made of polyester, since this material is particularly low-stretch and thus ensures a constant height.

In a further embodiment it is provided that the flat container designed as a sack has overlapping strips projecting laterally on its end faces. When the protective elements are laid, these overlap strips each lie above or below the adjacent protective element and in this way bridge the gap between the protective elements, thereby preventing gravel from penetrating into this gap and thus penetrating as far as the sealing membrane. The overlap strips can be glued to the adjacent protective element or - if they consist of weldable material - welded by means of hot air or other heat. This further improves the bond between the protective elements. The width of the overlap strips is based on considerations of expediency. Widths of 8 to 15 cm have proven effective.

It is particularly favorable if the overlap strips are continuations of the walls which lie flat one above the other, since the production is then particularly simple. The two layers of the overlap strip can be welded, glued and / or woven together or knitted together.

As an alternative to designing the flat container as a sack, there is also the possibility of designing the flat container as a flat trough with upstanding side edges, the trough preferably being closed on the top and essentially completely filled. Such a trough can also be quickly and easily laid to form a protective layer in the complete bond.

The tub should be essentially completely filled. It is particularly advantageous if the tub has dividers in the interior, because this keeps the sand in place even better. This also gives the tub a high height Dimensional stability that simplifies installation and transport. This is particularly the case when crossing separators are provided, where they should preferably cross at right angles to one another. Advantageously, the dividers are perpendicular to the floor and at least have the height of the side walls.

The tub should have a flat bottom and, in its simplest version - as well as the sack-shaped flat container described above - have a cuboid shape. Of course, other shapes that can be combined with one another to form a complete covering can also be provided.

So that no gravel can slip between the protective elements, the side walls of the tubs should be designed so that they partially overlap when laying. This can be done in that opposite side walls are designed to be correspondingly complementary, so that they fit together when they are placed against each other and overlap. This can be achieved, for example, by inclining the opposite side walls at the same angle. It is even better if the side walls are designed in a complementarily stepped manner so that the steps are stacked on top of one another when they are placed against one another. It is useful if the gradation of the side walls is halfway up.

A material is recommended for the tub which on the one hand gives the protective element sufficient stability for its transport, but on the other hand is so flexible or soft that it does not endanger the sealing layer itself. Plastics such as rigid foams made of polystyrene or the like are particularly suitable for this.

The manufacture of the aforementioned protective elements can run in such a way that a trough which is open at the top is first formed from plastic and then a layer of sand is continuously filled in at a uniform height. It is particularly advantageous that upstanding webs are formed at right angles to one another, the first webs running in one direction projecting beyond the second webs running transversely thereto, which corresponds to the spacing of the first webs, and then after Backfilling the sand, the protruding areas of the first webs are bent over onto the second webs, so that there is a closed upper side. Of course, there is also the option of simply closing the tub with a lid.

Finally, the invention relates to a method for producing a protective layer on a sealing sheet placed on a landfill floor, in which the protective layer of sand or a sand-like bulk material is applied to protect the sealing layer against damage. According to the invention, the sand or the sand-like bulk material is initially to be poured into flat containers with a substantially constant height, and these flat containers are then to be laid next to one another in a seamless bond. The flat containers can have the configurations for the protective element described above. The protective layer is expediently white or metal-colored on the top side, so that the protective layer does not heat up too much when exposed to sunlight, which could lead to warping of the sealing membrane. Of course, a protective layer made of geotextile can also be laid between the protective layer and the sealing membrane. Such a sheet can also be applied to the installed protective elements, which is useful for separating the sand layer and the gravel above if the flat container consists of a plastic that dissolves over time. The geotextile should be made of a durable plastic, e.g. HDPE.

Figur (1)

eine Schrägansicht eines Schutzelements in der Herstellungsphase;

Figur (2)

eine Schrägansicht eines anderen Schutzelements und

Figur (3)

einen Querschnitt durch mehrere Schutzelemente der in Figur (2) gezeigten Art.

Figur (4)

eine Schrägansicht eines als Sack ausgebildeten Schutzelements und

Figur (5)

einen Querschnitt durch zwei nebeneinandergelegte Schutzelemente gemäß Figur (4).

In the drawing, the invention is illustrated in more detail using exemplary embodiments. Show it:

Figure (1)

an oblique view of a protective element in the manufacturing phase;

Figure (2)

an oblique view of another protective element and

Figure (3)

a cross section through several protective elements of the type shown in Figure (2).

Figure (4)

an oblique view of a protective element formed as a bag and

Figure (5)

a cross section through two side-by-side protective elements according to Figure (4).

In figure (1) a protective element (1) is shown, which has a cuboid shape with a bottom (2) and four low side walls (3, 4, 5, 6). They are vertical from the floor (2).

At equal intervals, parallel to the short side walls (3, 4), the first webs projecting vertically from the floor (2) - designated by way of example with (7) - initially extend by an amount over the side walls (3, 4, 5, 6 ) project upwards, which corresponds to the distance between the first webs (7). Transversely to this and parallel to the long side walls (5, 6) run second webs - designated by way of example with (8) - the height of which corresponds exactly to the height of the side walls (3, 4, 5, 6). The first and second webs (7, 8) extend over the entire length between the side walls (5, 6) and (3, 4) delimiting them, so that there is a cuboidal division in the interior of the protective element (1).

Above the protective element (1) there is a sand funnel (9) which is filled with sand (10̸). Its width corresponds to that of the protective element (1). A roller (11) is also provided which can be rotated about an axis (12) which is mounted horizontally and extends parallel to the side walls (3, 4). The roller (11) is arranged so that its circumference on the underside is approximately at the level of the side walls (5, 6).

The protective element (1) is first manufactured in such a way that all of the first webs (7) project upwards in the manner described. It will then help in the direction of arrow A a conveyor device not shown here first move under the sand funnel (9). At the sand funnel (9), lower pouring valves, not shown here, are then opened. The protective element (1) is then moved so slowly under the sand funnel that the outflowing sand fills the interior up to the upper edge of the side walls (3, 4, 5, 6) one after the other.

As the process continues, the protective element (1) gets under the roller (11). This roller (11) then bends the upwardly projecting sections of the first webs (7) downward, thereby closing the upper side of the protective element (1) in sections. The roller (11) can be heated in order to facilitate bending and to allow the bent sections to be welded to the upper edges of the second webs (8). In the example shown, four protruding sections of the first webs (7) are already bent over, while the rear part of the protective element (1) is still filled with sand (10̸). When the protective element (1) has passed completely under the roller (11), its top is closed.

After completion of such protective elements (1), they can be laid next to each other on a sealing membrane to seal a landfill floor. For safety reasons, an additional geotextile can be placed between the protective elements (1) and the sealing membrane. A fabric can also be placed on the top.

In the figures (2) and (3) a protective element (15) is shown, which is characterized by the special design of its side walls (16, 17, 18, 19). The side walls (16, 17, 18, 19) are stepped at half height. The adjacent side walls (16, 18) jump back upwards by a certain amount, while the side walls (17, 19) project upwards by the same amount. The long side walls (16, 17) and the short side walls (18, 19) each have a complementary, ie complementary design.

This can be seen even more clearly from the illustration in FIG. (3), which represents a vertical section through several protective elements (15) placed next to one another. It can be seen that the sections projecting from the side walls (16, 17, 18, 19) complement each other so that there is no gap at the transition from two protective elements (15).

Otherwise, the illustration in FIG. 3 shows that the protective element (15) has the same internal division as the protective element (1) according to FIG. H. here, too, webs are provided in the interior - for example designated (20̸) - for dividing the interior.

Another protective element (21), which is designed as a closed sack, is shown in FIG. The protective element (21) consists of two superimposed textile webs (23, 24). Both textile webs (23, 24) are designed as ribbon fabrics made of HDPE, a stabilizing coating ensuring that the textile webs (23, 24) are low-stretch and resistant to displacement.

The two textile webs (23, 24) form overlap strips (25, 26, 27, 28) on all edges. In the area of the overlap strips (26, 28) on the long side, the textile webs (23, 24) are interwoven with one another, while in the area of the overlap strips (25, 27) on the transverse side they have transverse seams (29, 30). On the inside of the overlap strips (25, 26, 27, 28), the textile webs (23, 24) are arched apart and have a substantially constant distance of approximately 2.5 cm. The interior formed in this way is filled with sand with a grain size of 0̸ to 3 mm.

In the diagonally opposite corners, incisions (31, 32) are provided, which go from the outer edges of the transverse overlap strips (25, 27) to the transverse seams (29, 30̸), namely in continuation of the inner edges of the longitudinal overlap strips (26, 28). Instead of these incisions (31, 32), diagonal incisions can also be provided, as indicated by dashed lines in the other two corners.

This protective element (21) is produced in such a way that the textile webs (23, 24) are produced endlessly by tubular weaving and the longitudinal overlap strips (26, 28) are woven flat with one another. This textile tube is then cut through at appropriate intervals and the transverse seam (30̸) is first sewn. The interior is then filled with the sand from the opening formed by the overlap strip (25) up to the height of the transverse seam (29). The opening there is then sewn directly adjacent to the fill level through the seam (29). Finally, the incisions (31, 32) are provided.

The sectional view according to FIG. 5 shows - in each case partially - two protective elements (21, 33) placed next to one another. Both protective elements (21, 33) each consist of a top and a bottom textile web (23, 24) or (34, 35), which are essentially the same distance apart and are filled with sand (36). The distance between the textile webs (23, 24) or (34, 35) is limited by delimiting ribbons - denoted by (37) for example. They have already been woven in during the weaving process - initially at an incline - and have straightened up when the sand (36) is filled in due to its displacement effect. The latter has the result that - in the exemplary embodiment according to FIG. 4 - the transverse overlap strip (27) is essentially flush with the Textile web (23) comes to rest, while the opposite overlap strip (25) lies flush with the underside textile web (24). In addition, the limiting tapes (35) ensure that the protective elements (21, 33) have the same height over the filling area of the sand (36), since they each have the same length.

The protective elements (21, 33) are placed close together on their end faces. The overlap strips (27, 38) present there lie over or under the adjacent protective element (21, 33), i.e. one overlap strip (27) on the top of the protective element (33) and the other overlap strip (38) under the underside of the protective element (21). This will bridge the gap between the two protective elements (21, 33). In addition, they are welded to the respective textile webs (24) or (34) by the action of hot air.

Claims (14)

1. The use of a protective element (1, 15, 21, 23) constructed as a flat container of substantially constant height, into which a charge of sand (10, 36) or a sand-like bulk material is poured and which has an extent such that a plurality of such elements can be laid in combination without gaps to form a protective layer for the protection of sealing courses in waste dump construction.
2. A use according to claim 1, characterised in that the flat container is a closed sack (21, 33) with limp flexible walls (23, 24, 34, 35).
3. A use according to claim 2, characterised in that distance delimiters (37) are disposed distributed over the interior space of the sack (21, 33).
4. A use according to claim 3 , characterised in that the distance delimiters are constructed as boundary strips (37).
5. A use according to any one of claims 2 to 4, characterised in that the walls consist of a textile material (23, 24, 34, 35) which is impermeable to the charge.
6. A use according to claim 5, characterised in that the textile material (23, 24, 34, 35) is provided with a stabilising coating.
7. A use according to any one of claims 2 to 5, characterised in that the sack (21, 33) has laterally projecting overlap strips (25, 26, 27, 28, 38) on its faces.
8. A use according to any one of claims 2 to 6, characterised in that the overlap strips (25, 26, 27, 28, 38) are continuations of the walls (23, 24, 34, 35) which lie flat one on top of another.
9. A use according to claim 1, characterised in that the flat container is constructed as a trough (1, 15) with raised side edges (3, 4, 5, 6; 17, 18, 19).
10. A use according to claim 9, characterised in that the trough (1, 15) is closed on its upper side.
11. A use according to claim 9 or 10, characterised in that the trough (1, 15) preferably has intersecting separating webs (7, 8, 20) in its interior space.
12. A use according to any one of claims 9 to 11, characterised in that the opposite side walls (16, 17, 18, 19) are of complementary construction in each case, so that two protective elements (15) placed side by side overlap.
13. A method of producing a protective layer on a sealing course placed on the base of a waste dump, in which a protective layer of sand or sand-like bulk material is deposited to protect the sealing course from damage, characterised in that the sand (10, 36) or the sand-like bulk material is first poured into a flat container (1, 15; 21, 33) with a substantially constant height and the said flat containers (1, 15; 21, 33) are then laid side by side in combination without gaps.
14. A method according to claim 13, characterised in that a geo-textile course is placed on the protective layer.

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