Underground impermeable wall and process for producing thereof

(54) Underground impermeable tent and method of its production;

The underground impermeable tent for demarcation, especially of the hazardous waste landfill area, is composed of vertical elongated barrier members (3, 3a), which are fitted with their lower ends and the lower impermeable layer of soil are placed side by side and are connected to each other by their profile longitudinal connecting The ribs (1, 4) projecting from the two mutually mutually circumferential sides of the elongate shift plates (3, 3a) and containing thrusts (7) in the joints. When creating underground impermeable tents, the overlapping shafts (9) are first excavated into the soil groove (9) by successive dredging and partially overlapping shafts. 9) and First. serves for guiding the elongate damper dies (3, 3a), and after the damper dies (3, 3a) have been fitted. the groove (9) covers.

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The invention relates essentially to a storage system for the storage of hazardous waste and in particular to a method for preventing leakage and seepage of hazardous liquid components of waste materials into groundwater, the invention also providing an embodiment of a wall element from which an impermeable underground wall is formed.

The invention also relates to a device for assembling an underground impermeable wall from a system of interconnected and interlocking vertical wall elements of elongated shape. The individual vertical elongate wall elements are provided with interlocking connecting means which comprise sealing elements to form an impermeable seal preventing the penetration of liquid.

According to the invention, when opening an underground impermeable wall, vertical openings with a prescribed depth, width and / or diameter are first formed in the terrain surrounding the landfill, then vertical wall elements are fitted into the openings, sealing the joints between the vertical wall elements elements are filled with backfill and the entire created wall is covered with backfill on both sides.

According to the invention, the solution can also be used to prevent the leakage of different materials to the sides from their storage, while it is possible to prevent the leakage of both liquid and gaseous substances, while the solution can be used in different terrain and soil conditions with similar favorable results.

The solution according to the invention represents an efficient and cost-effective storage system, as will be seen from a more detailed description of the advantages of the invention.

An alternative method of finishing a subsurface impermeable wall according to the invention involves interconnecting the screening wall elements and welding the joints of the wall element fasteners together to achieve greater structural integrity of the wall and better sealing of the joints.

The invention also relates to a method of laying an underground impermeable wall, in which guide box templates are used for fitting wall elements or components, which is intended to ensure correct guiding of sliding wall elements into the wall system and which comprises means for assembling the wall even in soil conditions where there is danger. occurrence of underground cavities.

State of the art

Hitherto, the sealing underground walls are formed from elongate profile panels, mounted next to one another in a vertical position and connected to one another by connecting locks formed on the lateral contact surfaces of the wall profile panels. Some of these underground screening structures are described and illustrated, for example, in U.S. Pat. No. 2,101,285, 2,937,065, 2,961,731, 3,202,412, 3,411,305 3,848,855, 3,866,705 and 4,808,039. However, these solutions are completely different from the essence of the invention and also the purpose and field of their application has a different focus.

From a cursory comparison of the contents of these patents with the essence of the invention, it is clear that the prior art represented by these solutions is different from the subject matter of the invention. Most, if not all, of these documents contain completely different constructional and procedural features.

U.S. Pat. No. 2,101,285 discloses a cylindrical locking pile provided with longitudinal locks on opposite sides for interengagement.

It is clear from the description of this document that these bar piles are used to form sheet pile walls around pits in the construction of dams, bridge piers and similar objects. It is clear from the description that these elements are not suitable for the formation of barrier impermeable underground walls, although it is possible to form retaining walls for said structures. These profile piles are not primarily adapted for inserting seals into joints.

U.S. Pat. No. 3,302,412 describes a profile pile or sheet pile with connecting locks and also a method of fitting it, in which sealing elements are inserted in the direction of their axes to seal the joints between them. This system is also different from the wall according to the invention and is of several

- 3 reasons also less advantageous. The solution according to U.S. Pat. No. 3,302,412 is directed to rolled profiled sheet piles from a profiled platform for forming sheet pile walls or pits, but is not applicable for forming sealing screens in the field. Installation of these sheet piles is impractical, expensive and would not be suitable for use in various types of soils and rocks.

For example, the gripper 24 of FIG. 3, used to extract uncoupled soil particles, is not useful for removing material from the cavity 16 during plowing of the sheet pile. It is not possible to get the captured soil from the excavated space in sufficient quantity, because the tolerance in the connection of the grapple edge with the cavity is very small to assume material fall into the grab reach area. with grown .land soil.

Although these tolerances of the trapping system are too small to allow aggregated material to be raking, they are, on the other hand, large enough to allow free leakage of liquid sealants, and leakage occurs to such an extent that it is not possible with this design. achieve an impermeable seal at a traceable level.

The wall elements according to U.S. Pat. No. 3,302,412 are provided with brackets 30, shown in FIG. Tolerances must be left between the individual parts of the lock, ie between the rib and the groove, otherwise the connected parts could not be pushed together smoothly. The construction of these parts is very expensive and highly impractical, the individual elements must be provided with a large number of holes during production and perfect alignment of the holes against each other in both grooves or cavities must be achieved. and mounting and guiding the mining tool as described in this document is very difficult and time consuming. Thus, although this system is applicable in practice, its operation is associated with considerable costs and its production is complex.

U.S. Pat. No. 3,886,705 comprises an hollow component made of extruded plastic and also a structure composed of these components, which hollow component is shaped to form partition walls and partitions or similar structures and is dimensioned to transfer vertical loads from the upper part. parts of the structure. Although the described construction envisages the use of sealing tapes in order to prevent snow or rain from entering the structure, the design of the contact and sealing details is not suitable for use for the purpose for which the impermeable wall according to the invention is solved. In addition, the construction according to U.S. Pat.

U.S. Pat. No. 3,411,305 discloses a cylindrical pilot with connecting locks for forming folded walls, which is an alternative to more conventional profiled sheet piles with connecting locks, and its basic difference compared to these conventional sheet piles is its greater bending stiffness, so that this pilot is suitable for finishing. temporary barriers, walls, smaller dams, pillars, bank pillars and retaining walls and the like, where it is necessary to create a more load-bearing structure.

This document also describes a cylindrical pile unit of sufficiently strong material to form higher strength load-bearing and retaining walls, but it is not apparent from the entire description of this unit that the formed wall or other structure is impermeable to fluids. Therefore, this solution is not suitable for use according to the invention, and in addition the structure according to the invention is not aimed at achieving high wall structure strength, since such a requirement is unnecessary in the solution according to the invention, whereas in said known solution the strength requirement is paramount.

U.S. Pat. Nos. 2,937,065 and 2,961,731 contain two completely different sealing systems for ensuring impermeability to fluids which have nothing to do with the solution according to the invention.

Another method for storing and storing hazardous waste is also known, in which a clay slurry screen is set up around the landfill to prevent contaminated liquids from escaping from the landfill. In this known process, a groove is formed in the terrain around the waste disposal site, extending to a sufficient depth up to an impermeable natural soil layer, for example to a clay layer.

The basic problem in creating sufficiently deep ditches and furrows is the insufficient cohesion of the grown soil and usually the small angle of the natural slope of the soil, which so often tends to flood the excavated furrow. Therefore, it was usually necessary to use pile or sheet piles and other elements in this method to fasten and strengthen the groove walls. However, since most known sheet piles are not able to prevent leakage penetrating the sheeting thus formed, the filling of the excavated grooves with other expensive material, such as bentonite or natural clay, has been used to form an underground impermeable barrier against leakage of stored substances.

The underground impermeable wall according to the invention should be more cost-effective than the cheapest clay slurry system because it does not need load-bearing pile elements or other means to absorb and prevent soil pressure, since the system according to the invention does not present this danger.

Also, the additional acquisition costs of the system of the invention should be substantially less because approximately one-hundredth of the original amount of bentonite or similar sealing material is sufficient to seal the screen; Although bentonite prices have fluctuated considerably recently, they can go hand in hand with significant transport costs.

The system according to the invention should also not require the equipment necessary for driving piles or sheet piles, heavy lifting and conveying equipment and a large amount of work on site as is the case with the known systems described.

- 6 Summary of the Invention

The disadvantages of the hitherto known underground walls are eliminated by the solution according to the invention, comprising a reliable impermeable system which is relatively economical and less dangerous for its surroundings.

As the previous analysis has shown, the prior art does not contain an inexpensive and at the same time sufficiently impermeable boundary system for the perfect closure of a hazardous waste landfill. substances that would be able to prevent the escape of toxic materials from the storage area of ​​this material. The only system capable of perfectly preventing undesired leaks is a system with a sealing screen made of sealing slurry, which is also the only system comparable to the solution according to the invention, but which is considerably more expensive because it also needs to form a sheet pile wall from profile sheet piles.

The essence of the underground impermeable wall according to the invention lies in the fact that the underground wall is composed of a set of barrier members, each consisting of an extruded cylindrical core part provided on its circumferential surface on opposite sides with profile connecting longitudinal ribs spaced apart by center angle 180 °. The profile connecting longitudinal ribs are formed in the profile in a complementary shape, i.e. one longitudinal rib has a plug-in shape and the second longitudinal rib has a sleeve shape for the first longitudinal rib, the two connected profile ribs being shaped for connecting the barrier members by longitudinal sliding in an independent direction.

Each of the connecting longitudinal ribs of the barrier elements is provided with a groove for forming a vertical through cavity or chamber after the two connecting longitudinal ribs have been assembled into each other. This vertical chamber can be filled with sealing material in order to prevent the escape of undesirable harmful substances from the landfill area into the surroundings and thus also into the surrounding groundwater.

However, the two connecting longitudinal ribs do not have to be arranged at a central angle of 180 ° to each other, i.e. they do not have to be exactly opposite each other on opposite sides of the core part, but can be

- 7 placed in any circumferential position, for example they can be spaced apart at a central angle of 90 ° in order to form corners of the underground wall, while of course barrier barriers with different angular distances of longitudinal ribs can also be used to delimit oval, kidney-shaped and similar storage areas, or for creating various necessary geometric floor plan shapes of underground walls. Thus, the storage area does not have to be circular or square, but can have any floor plan. By interconnecting differently arranged connecting longitudinal ribs of the barrier members, carried out by inserting one longitudinal rib into the adjacent longitudinal ribs of the connecting barrier member, the necessary system of the underground wall is formed.

The underground impermeable wall according to the invention is to be designed so that the lower ends of the vertical barriers extend to a depth in which they extend into the clay vegetation layer at ground depth or another impermeable layer to form a closed storage boundary on all sides. Thus, different sites will require different depths of underground walls, created from different lengths of barrier members. Under normal conditions, it is generally not necessary to lay this underground wall at depths greater than 12. It is therefore possible to use conventional means of transport and assembly by assembling the underground wall according to the invention. Clay is not the only impermeable soil and rock, and the system according to the invention can also be used in combination with other impermeable layers.

Another operation in forming an impermeable subterranean wall according to the invention is to incorporate a sealant into the foundations delimiting the subterranean wall in order to prevent the leakage of fluids below the lower end of the subterranean wall.

In a preferred embodiment of this process, clayey bentonite, which has hitherto been used in the installation of sealing screens in the soil, is introduced into this base area, but in this case the bentonite slurry is deposited in a substantially small amount. The foundation seal should be formed only to the extent necessary to fill the penetration area of ​​the underground wall with a horizontal impermeable layer of soil, for which, for example, a sealing layer height of about 10 cm is sufficient. In some cases, it is not even necessary to create this seal.

The system according to the invention also comprises further alternative or optionally additional operations to increase the structural integrity of the underground impermeable wall and to increase the sealing capacity.

These additional operations include, in particular, the welding of the joints between adjacent barrier barriers in the region of the vertical sealing chambers, this welding being carried out before the sealing material is injected into the chambers. The welding is preferably performed by means of a specially designed and constructed welding probe, which is lowered into the sealing continuous chamber after the assembly of the barrier parts. After welding the contact surfaces, a sealing material can be inserted or injected into the vertical continuous chamber to fill the remaining space of the cavity.

In order to install the system according to the invention in incoherent soils, where there is a risk of the excavation walls slipping, guide boxes are used in the solution according to the invention, reaching to the bottom of the excavated groove. The guide box of the system according to the invention has five important tasks, firstly it forms a supporting structure which is able to absorb the pressure of the soil or the collapsing soil into the trench and which prevents clay from entering the area into which the barrier elements are to be inserted. complications in the mutual assembly of individual barrier parts in a row. The second function of the guide box is to create a guide template for the correct fitting of the new barrier part during insertion and to guide it in the correct position during the entire insertion. Thirdly, the guide box protects the pre-assembled baffles against damage by the twist drill when holes are made for the other baffles by this tool, the fourth task of the guide box being to protect and guide the helical bore when digging the hole. The last, no less important task of the guide box is to enable and ensure the gradual controlled backfilling of the excavation when pulling out the guide box according to the invention.

The system according to the invention envisages digging a trench for the underground sealing wall by dredging or excavating the soil with grabs, but other digging methods and means can be used just as well to achieve satisfactory results.

Thus, the solution according to the invention comprises a hazardous waste storage system which is efficient, useful, very cost-effective and which provides sufficiently reliable protection against the escape of impurities into the surrounding groundwater in particular and into the surrounding soil.

The system according to the invention represents a system for keeping hazardous waste in the scope of a selected landfill, formed of individual barrier elements, connected to each other by a form engagement in connecting locks.

The invention addresses the storage of hazardous substances, especially waste, in landfills, the creation of which can be easily adapted to the nature of the site available for the establishment of the landfill.

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Another object of the invention is to provide a system for storing hazardous waste which ensures the safe storage of these materials for a period of time which is as long or longer than in the landfills used hitherto.

The system of the invention has the ability to keep hazardous wastes safe until such wastes can be disposed of or neutralized as needed.

The invention also solves the sealing of the joints between the adjoining adjacent barrier members, in which the joints are closed very perfectly by welding the abutting parts by means of a specially designed welding tool lowered into a continuous vertical sealing chamber.

The invention also relates to a method of setting up a storage system for the storage of hazardous waste, comprising a circumferential impermeable screen of barrier elements, which method also comprises a method of using a guide box for mounting these barrier elements.

Overview of figures in the drawings

Exemplary embodiments of the invention are shown in the drawings, in which Fig. 1 shows an axonometric view of a preferred embodiment of an impermeable screen in the form of an underground non-load-bearing wall in the form of a guide box as a template or a guide device, before the final backfilling of the groove, FIG. 2 a vertical section of a part of an exemplary embodiment of an impermeable wall shield according to the invention, showing the sealing function of the lower impermeable soil layer, forming an impermeable fluid barrier and preventing leakage of toxic calf waste by the bottom of the system, and also showing the use of a clay seal in the heel area of ​​the impermeable sealing wall. . 3 an axonometric view of an exemplary embodiment of a vertical barrier barrier for providing an impermeable screen, provided on its circumferential surface with two mutually opposite connecting longitudinal ribs in a plug-in and embracing embodiment for interlocking, arranged at a central angle of 180 ° to each other, FIG. from above to the barrier element of FIG. 3, showing more specifically an exemplary embodiment of connecting longitudinal ribs, one of which is always adapted to be inserted into the longitudinal rib of an adjacent barrier member and the other longitudinal rib is adapted to receive an opposite adjacent barrier member; FIG. 5 is a top view of another exemplary embodiment of the barrier member. , similar to the example of FIG. 3, but the two opposite connecting longitudinal ribs are arranged at a central angle other than 180 [deg.] with respect to one another; FIG. 6 axonometric view of a solidified seal according to the invention, which may arise in the sealing cavity or chamber and in adjacent cavities around the sealing chamber, arising from tolerances in joining the baffles if the contact surfaces are not welded to each other, Fig. 7 , showing a possible adaptation of the formation of the impermeable screen to specific local conditions and the floor plan of the land for the establishment of a landfill, FIG. 8 Fig. 8a is a view of a first operation involving digging a hole with a screw drill with the desired diameter and length to create a sufficiently deep hole; 8b shows a top view of a second operation in which an exemplary system according to the invention is fitted by means of a guide box placed in a hollow hole, FIG. 8c is a top view of a third operation in which two barrier members are fitted and interconnected by inserting connecting longitudinal ribs into each other, which have been placed in holes in a guide box located in the first excavated hole next to the newly excavated adjacent hole, and FIG. 8d is a top view of a fourth operation of the underground impermeable wall assembly method in which the first guide box was removed and replaced with a second guide box in such a way as to catch one barrier member of the original pair together with connecting locks of these barrier members and still unfilled sealing chambers. Giant. 9 is a view of a plug that can be inserted into the lower end of the core portion of the elongate barrier vertical member; FIG. 10 Fig. 11 is a vertical sectional view of the lower end of the core portion of the baffle with the stopper fitted of Fig. 9; and Fig. 11 is a horizontal section of the joint area of ​​two adjacent elongate baffles, mutual welding of the joint area and filling the sealing cavity with sealing material.

Examples of embodiments of the invention

As can be seen in Fig. 1, the storage system according to the invention comprises an impermeable underground wall in the form of a non-load-bearing screen delimiting the storage space and composed of a group of interconnected elongate barriers which are interconnected by slidingly sliding the interlocks in the longitudinal direction to form a continuous underground vertical barrier, which is then perfectly sealed, this underground wall being formed in the groove 2 in the terrain surrounding the waste disposal area. The method of making this wall and also the equipment for carrying out this method will be described in the next section.

Giant. 3 quite clearly illustrates an exemplary embodiment of a barrier part 2 according to the invention, which consists of a hollow cylindrical core part 6 of, for example, polyethylene, polyvinyl chloride, polypropylene, polyurethane and similar plastics and two profile connecting longitudinal ribs 2, 4 formed on two mutually opposite parts. the circumferential surfaces of the cylindrical core part 6, located for example in positions corresponding to a central angle of 180 °. The first connecting longitudinal rib comprises a shaped insertable portion of the locking connecting system which, in the connected position, is slidably longitudinally inserted into the second connecting longitudinal rib 4 of the adjacent barrier member J provided with a sleeve portion to receive the insertion portion of the first connecting longitudinal rib 2 to form an impermeable barrier.

A groove 2 or cavity is formed in the face of the insertion portion of the first connecting longitudinal rib 2 to form a sealing cavity for accommodating a seal. The construction of this sealing chamber will be described in the next part of the description.

The second connecting longitudinal rib 4 is provided at its front with a receiving and embracing part of the locking connecting system, comprising a profile groove 4a for inserting the insertion part of the first connecting longitudinal rib 2 ». ⁱⁿ at the bottom of which a groove pocket is also formed for accommodating a seal. As can be seen from Fig. 3, the basic part of the elongate barrier member 6 is a hollow cylindrical core part 6.

Giant. 4 and 5 show in greater detail various structural details of the elongate barrier member 3 according to the invention, intended to form an impermeable screen wall.

The insertion first connecting longitudinal rib 23 in addition to the groove 2 for accommodating the seal is provided with guide arms 21 »which are guide elements during insertion and which are in sliding contact with the guide arms 10 of the second connecting longitudinal rib to ensure a perfect connection of the connecting lock within tolerances and, in addition, a further improvement in the sealing of the joint area between the side panels placed next to one another has been achieved in order to prevent fluid leakage. Retractable first connecting longitudinal rib 2 j^E provided between the guide arms 22 ^and the core part 6 by a locking constriction 12, which is in sliding engagement with the ends of the snap-in flanges 13 at the edge of the profile groove 13a of the second connecting longitudinal rib 4.

As shown in Fig. 5, the first connecting longitudinal rib 2 and the second connecting longitudinal rib 4 of the alternative exemplary embodiment of the elongate barrier member 3a need not be arranged exactly opposite each other while maintaining a central angle of 180 °. Both of these longitudinal ribs 2, 4 can be spaced at a distance corresponding to a central angle of 45 ° to form corners for underground walls with a triangular floor plan, 90 ° to form corners for walls with a square or rectangular floor plan, or other_him center angle.

The elongate baffles% can be connected to additional elongate baffles 3a, the connecting longitudinal ribs 24 of which have a mutual distance corresponding to a central angle other than 180 °, and thus it is possible to form baffle underground walls of a plan shape other than rectangular. For example, it is possible to form underground impermeable walls with a kidney-shaped floor plan, shown for example in FIG.

As can also be seen in FIG. than necessary, which significantly increases costs.

Giant. 1 also shows a process for preparing an impermeable underground wall according to the invention; the first operation of this process is to dig a trench £ around the perimeter of the land on which the landfill is to be created. The groove 6 has a sufficient width to accommodate the elongate barrier members 2 »3a without being caught by the rock on the walls of the groove 2, so that the soil does not slip. The groove £ must also be of sufficient depth for its bottom to extend into a water-impermeable layer of soil, for example a layer of clay or material with similar properties.

The vertical elongate barrier parts J, 3a are connected to each other by inserting their locking elements in the longitudinal direction into each other in order to

14 the first connecting longitudinal rib 6 is inserted into the second connecting longitudinal rib 4. After the locking parts of the elongate barrier parts 5, 5a have been connected to each other, an expanding and hardening sealing compound, for example silicone, can be injected into the sealing chamber 35. The sealing chamber 33 is formed by the inner space of the groove 2 in the first connecting longitudinal rib 6 and the groove pocket 6 in the second connecting longitudinal rib 4, which define a continuous hollow space. The sealing compound fills the inner space of the sealing chamber 33 and penetrates by injection pressure into the curved tolerance slots remaining between the first connecting longitudinal rib 6 and the inner wall of the profile groove 4a of the second connecting longitudinal rib 4, where the solidified sealing mass forms sealing flaps 7a on both sides , formed by solidification of the sealing compound, as can be seen in FIG. 6.

To form the corner of the underground impermeable wall, an auxiliary partition 5a is used, the second connecting longitudinal rib 4 of which is arranged at an angle of 90 ° to the first connecting longitudinal rib 7.

As can be further seen from FIG. When filling the core part 6 of the infill before the mounting member 6 can be fitted, the weight of the infill 8 can help to insert the newly fitted vertical barrier member 6 into engagement with the previously fitted vertical barrier member £.

Fig. 1 also shows the use of the guide box 16, which has already been mentioned in the previous description. The guide box 16 is used in those cases where it is necessary to ensure precise guidance of the installed vertical barrier parts £, £ or where it is necessary to prevent the soil from sliding off the excavation walls when installing the underground wall elements. The guide box 16 has the shape of an elongate hollow body and a number of vertical guide cavities 16a of profile cross-section, which are guide openings for guiding the fitted vertical barrier parts 5, 5a. The method of mounting these vertical barrier members 3, 5a will be described in more detail in the explanation of the examples of Figs. 8a to 8d.

Fig. 2 is a vertical section of a vertical underground impermeable wall in the form of a non-load-bearing barrier against the penetration of toxic fluids, shown in a finished state next to a storage area with landfilled waste material from which harmful substances can be leached in the direction of arrows 24.

As can be seen in Figure 2, the boundary impermeable wall is installed in a vertical position below ground level to a depth sufficient for its heel to be formed in the impermeable, fluid-impermeable layer 20, which is a clay layer or layer with similar properties. The underground vertical impermeable wall, together with the clay horizontal impermeable layer 20, forms a perfectly closed container on all sides.

In the exemplary embodiment shown, the deposited toxic waste material 25 contains a contaminated liquid or suspension which may seep in the direction of the arrows 24 through the deposited toxic waste material 23 and the growing soil 22 into the aquifer 21 where groundwater is contaminated and if the landfill area is not perfectly sealed on all sides by a barrier, such polluted groundwater could leak into the environment and pollute watercourses, lakes and water sources. However, in an exemplary embodiment of the invention, the contaminated groundwater from the aquifer 21 cannot escape to the sides either in the direction of the arrow 24 or the lower impermeable layer 20 deeper into the subsoil.

The solution according to the invention prevents the escape of impurities in the direction of the arrows 24 and also interrupts the flow of water in the aquifer 21 below the contaminated area.

The underground wall, provided with a seal made of sealing strips J, perfectly prevents the escape of dirt from the defined space and also does not allow the leakage of degraded water. To prevent the leakage of contaminants through the joint between the base of the vertical impermeable wall and the horizontal impermeable layer 20, a layer 25 of bentonite or similar material can be placed on the bottom of the groove 6 before installing the vertical barrier members 3a, into which the lower faces j $ b of the vertical barrier members ^ a. To further secure this contact area against leakage, the underground wall can be slightly sunk into the impermeable layer 20 in order to further improve the sealing of the system into the underlying impermeable layer 20 of soil.

The excavation of the trench% for the construction of the impermeable underground wall according to the example of Fig. 1 can be carried out without sheeting or other aids only in very cohesive soil, but is not feasible in irrigated soils, sandy soils and other loose soils.

In these difficult conditions, where excavation is a significant problem, other excavation methods must be used, which must be properly designed with regard to the considerable depth of the underground impermeable wall, which is often around 12 m or more, and the prepared excavation must be clean and not backfilled before mounting the vertical partition members 5, 5a «

Collapsed sand, stones or similar particles could be a significant obstacle for assembling the individual barrier members 2 »5a into a continuous wall. In addition, the soil particles attacked at the bottom of the groove 2 during the installation of the barrier members 2, 3a could disrupt the perfect connection of the vertical screen with the horizontal impermeable layer 20 and thus the contaminated fluid could escape through the gap between the two parts or under the underside of the bentonite layer 25.

For these reasons, an alternative vertical wall finishing method has been proposed that is particularly suitable for these conditions. This alternative mounting method is shown in Figures 8a to 8d and is based on the use of a guide box 15 of a similar type to the guide box 16 of Figure 1.

Giant. 8a shows a first operation carried out during the construction of an impermeable vertical wall according to the invention, in which a cylindrical shaft 18 is excavated in the soil with a helical drill or other tool. This type of excavation has been found to be less prone to wall slippage compared to vertical straight grooves, as the walls of the cylindrical shaft 18 form vaults on all sides, which maintain better material cohesion, with gentle mining having a significant effect on keeping the soil in the growing position. a helical drill, which, when engaged, to some extent compacts the soil around the borehole and does not disturb it as when digging a straight trench with an excavator.

A problem with this digging process, in which the space for the vertical wall is created by a system of cylindrical shafts 18, is the excavation of mined soil from the drilled adjacent well into the previous cylindrical shaft 18, as seen in Fig. 8c, which is connected to the new cylindrical shaft. shaft 18.

Therefore, after excavating the first cylindrical shaft 18 with a twist drill, the first two-hole guide box 15 shown in Fig. 8b, which is the initial guide and ejecting element, which is fitted to the first cylindrical shaft, must be inserted into the first cylindrical shaft 18 when performing this alternative procedure. 18 and which also serves as a guide template for interconnecting two adjacent vertical elongate barrier members 2 into each other. As already mentioned, the first two-hole guide box 15 also serves to guide the two vertical barrier members 2 inserted into each other during their assembly into a part of the underground wall and at the same time prevents complications associated with the sliding of the soil from the excavation walls.

and

Fig. 8c is a top view of the third and fourth operations of this alternative fitting procedure, showing the fitting of the vertical elongate barrier members 2 into the first two-hole guide box 15 and the excavation of an adjacent cylindrical shaft 18. The first two-hole guide box 15 is used for initial insertion into the first. cylindrical shaft 18, which generally has a diameter of about 75 cm.

The barrier members 2 can be installed in the excavation area after the first two-hole guide box 15 has been inserted by inserting into the guide profile recesses of the first two-hole guide box 15 and inserting the locking parts together, or by inserting the barrier members 2 into the first two-hole guide box 15 before inserting it. into the trench, so that the first two-hole guide box 15 | is already inserted into the cylindrical shaft 18 together with the barrier parts 2 ·

The insertion of the barrier parts 2 into the first two-hole guide box 15 outside the excavation has the advantage of easier handling and easier storage of the system thus formed in the cylindrical shaft 18.

The barrier members J, which are connected to each other and inserted together in the first two-hole guide box 15 outside the excavation, can be filled with sand with another filling material, so that the first two-hole guide box 15 gains more weight and is easier to lower into the excavation. they connect the barrier parts 2 to each other.

As can be seen from Fig. 8c, the closed side of the first two-hole guide box 15 faces the second cylindrical shaft 18a and prevents the closed part of the second connecting longitudinal rib 4 of the supporting member J from falling by the closed side and at the same time allows undisturbed and free excavation of adjacent cylindrical shafts 18a.

Giant. 8d shows a top view of a fourth, fifth and sixth operation of an alternative subassembly installation procedure, comprising removing the first two-hole guide box 15, fitting the second three-hole guide box 17 in such a way that one of the holes slides onto one of the installed barrier members. 2 and the remaining part of the second three-hole guide box 17 extends into the second cylindrical shaft 18a, and finally the fitting of further vertical baffles 5 and their interconnection by insertion into each other.

As can be seen in Fig. 8d, the open side of the second three-hole guide box 17 surrounds the interconnected connecting longitudinal ribs 24 of the first two vertical baffles 5A, 5B and the opposite closed end of the second three-hole guide box 17 faces the area where it is to continue. excavation of another shaft,&gt; a is located next to the next mounted JD barrier.

Three further continuations of this alternative method of assembling the underground wall in the incoherent soil, the steps of Figures 8c and 8d are repeated until the entire wall is completed.

In the example in FIG. In this example, the corner guide box £ 6 is shown in FIG. 1 provided with a side opening for connecting the first connecting longitudinal rib χ of the corner barrier member 3a, perpendicular to the longitudinal plane of the corner guide box 16, with the previous row of barrier members 2 »assigned to the newly assembled group of barrier members 2 ⁷ angle other than 180 °.

After inserting the connected vertical elongate barrier members 2 &amp; apos; &amp; apos; into the joint, the sealing chambers 33 are filled with a seal and the hollow core parts 6 of the vertical elongate barrier members 2 &amp; apos; 3 &amp; apos; The excavated groove £ around the finished underground wall is then included. It is advantageous if the vertical elongate barriers J are not completely sunk below ground level after they have been installed and the groove 2 has been included, but it is more appropriate to allow part of the vertical wall to rise above the ground so that surface water cannot overflow from the landfill area over the vertical wall crown. even run-off rainwater can absorb dirt in the landfill area. The upper end of the barrier members 2 can be closed with a cap or similar element in order to prevent the core part 6 from being filled with water, which could freeze inside the barrier members 2 and tear the walls of the barrier member 2 in winter.

Giant. 9 shows an exemplary embodiment of a lower plug 19, which is intended to be inserted into the lower end of the vertical elongate barrier members 2 ,. The lower plug 19 is welded to the lower end of the barrier member 15 after welding into the core part 6. The lower plug 19 is necessary in particular when inserting the barrier members 2.^d° guide boxes 15, 16, 17 after previous filling with sand or other filling 8 and before placement in the excavation area.

The lower plug 19 may be fitted entirely at the lower end of the core part 6 of the barrier members 2 or may be welded at a small distance from this lower end, for example at a distance of 1.25 cm to 12.5 cm, so that the lower end of the heavy and loaded barrier the part 2 could sink in the clay impermeable layer 20 of the soil and could thus ensure a more effective sealing of the joint. The barrier members 2 may also have chamfered faces or may be fitted with the application of vibration to achieve further pushing into the impermeable layer 20.

Giant. 11 shows another alternative embodiment of the system according to the invention, specifying the position and design of the heat-sealed seam or weld 27 in the space of the groove pocket 5 before grouting the sealing compound 28. The weld 27 ensures complete tightness of the joint between the first connecting longitudinal rib 1. and the second connecting longitudinal rib 4 and eliminates the adverse effect of any tolerances that may occur in the joint, and at the same time increases the integrity of the structure by permanently connecting the vertical elongate barrier members 2, 3a.

Although an exemplary embodiment of the invention is aimed at creating an impermeable sump for storing hazardous wastes above the impermeable bedrock, the solution according to the invention can also be used for other purposes, for example for creating soil protective and screening dikes and barriers etc.

The design features of the underground impermeable wall according to the exemplary embodiments represent only some of the possible features that can be varied both in their particular construction, mutual arrangement and use, and in their conceptual use. Thus, the exemplary embodiments of the foregoing description and drawings serve primarily to illustrate the invention, but are not intended to be limiting in any way.