EP0663470B1 - Process for obtaining a superstructure for railway tracks - Google Patents

Abstract

The structure of a railway permanent way, esp. for high speed rail traffic and heavy loadings, has a concrete trough (2) below the rails (3) of a reinforced concrete material. It has two laying surfaces (5) for the sleepers, projecting over the sole surface plane of the trough (2). When the track has been aligned, the hollow zones are filled with a compressed ballast (9) together with a mortar suspension (14), to give a rigid ballast bed (9a). Pref. the concrete trough (2) has a min. concrete rating of B 25. The sleeper support surfaces (5) have a defined laying surface, at least 20 mm over the sole surface plane. A barrier agent (10) is a sprayed material such as bitumen, at the inner surface (2a) of the trough (2) to prevent durable adhesion contact between the mortar suspension (14), or it is a thin polyethylene film which allows force transmission between the ballast bed (9a) and the inner surface (2a) of the concrete trough (2).

Description

The invention relates to a method for producing a superstructure for railway tracks, in particular for lines for high speeds and loads, with a concrete trough laid in the track direction with a U-shaped cross section and a ballast bed and track grating arranged therein.

A known method of this type according to DE 41 00 881 A1 discloses prefabricated parts which can be lined up in the track direction and can be laid in a curve, which form the concrete trough, in which the track grating is arranged on a resilient ballast bed. The resilient ballast bed is compacted with plastic at least on its surface. An expensive synthetic resin or a multi-component adhesive is proposed as plastic. This superstructure is associated with the disadvantage of a homogeneity which changes as a result of slurries, and with a bond between the ballast bed and the inner surface of the concrete trough, which considerably hampers repair work.

The method of manufacture of this superstructure is essentially based on the construction principle of the "Rheda / Sengeberg" type. When manufacturing the Rheda superstructure, a Prefabricated track grate, consisting of rails, prestressed concrete sleepers and reinforcement, aligned with the help of spindles on a previously prepared concrete support plate and concreted in. The rail deflection required to distribute the traffic load over several sleepers is achieved by means of an elastic rail fastening. The modification of this superstructure, which was installed for the first time in the Sengeberg tunnel of the new Hanover-Würzburg line, is that the concrete slab made with a slipform paver is trough-shaped, so that the side cheeks serve as abutments for the horizontal spindles, as formwork for the filling concrete and as a running surface serve for the concreting device for the installation of the filling concrete. A film is inserted or a release agent is sprayed on between the cast-in track grate and the concrete support plate designed as a trough, which makes it possible to lift the carriageway plates when repairing or renewing. However, this system is associated with the disadvantage of consistently costly and time-consuming concreting of the track gratings, which not only requires special machines, but also prevents preloading from rolling traffic.

From AT-PS 370 461 a method for the production of a superstructure of the type mentioned is known, in which the concrete trough consists of prefabricated reinforced concrete parts of approximately 2 m in length, in which a concrete insole as a support and thereafter for absorbing transverse forces after the use of an internal formwork from pre-cast reinforced concrete parts in-situ concrete is used to stiffen the side walls. This time-consuming production does not only require at least four individual parts for the concrete trough, but also a very precise surface of the concrete inner shell as a support for the track grate. The ballast bed, which is resilient due to its cavities, requires regular maintenance, especially at high speeds and loads, since the position of the track grate and / or the homogeneity of the ballast bed changes due to slurries. In addition, the overlying dust of the ballast bed affects the eddy current brakes of high-speed trains when braking.

From DE-OS 23 06 428 a method of a different type has become known, in which a first layer of ballast is rolled on a substructure and then small stones divided on its surface fill the gaps. Two elastically hardened layers of a fast-curing injection material running parallel to this and relatively large area are applied to this layer underneath the track areas and large, plate-shaped sleepers are placed thereon, to which the tracks are attached. The space between these plate-shaped sleepers, which are laid in the longitudinal direction, and the drainage trenches which are arranged equidistantly on both sides and have a U-shaped cross section are filled by an upper layer of ballast with a height of approximately 15 cm to 25 cm. This layer of gravel is then covered with another waterproof layer. This superstructure has the disadvantage of a complex production which can only be carried out with special machines, with a fast-curing injection material also being introduced into the lower area of the ballast must and therefore the construction and the work must be carried out not only in sections, but also in stages.

From DE 37 36 943 C1, a method for producing a superstructure of a different type has become known, in which a separating layer in the form of an applied film is applied to a concrete substructure, on which then reinforced in-situ concrete is applied with joints that run transversely to the longitudinal direction of the tracks and that is made of prestressed concrete existing thresholds can be used in the lower area in the in-situ concrete. After the in-situ concrete has set, an airborne sound-absorbing layer of aggregate concrete that ends below the upper edge of the sleepers is applied. This superstructure, which is expensive to manufacture, also requires regular reworking of the aggregate concrete, which also favors settling of dust and other dirt particles and thereby affects the eddy current brakes of high-speed trains. Due to the lack of a concrete trough, this superstructure requires costly and time-consuming formwork, offers less security against lateral forces and can only be driven on by rolling traffic after the in-situ concrete slab in the superstructure has set.

Finally, from DE-OS 20 63 727 a method for stabilizing a ballast bed has become known, with which the individual stones of the ballast structure are glued flat by a plastic that fills the cavities between the stones. As a plastic, a two-component resin is called, the under Foam cures so that the cavities between the stones are completely filled. This method is very expensive due to the plastic used and requires a gradual backfilling and / or formwork, because otherwise the plastic can flow into the environment outside the ballast bed. Repairs are extremely time consuming and difficult. Furthermore, the elasticity of the ballast bed is retained due to the plastic used, which is by no means desirable for high-speed trains.

Starting from this prior art, the invention has for its object to provide a method for producing a superstructure for railway tracks of the type mentioned, which can be installed and repaired with the conventional superstructure equipment, in which all work can be carried out without using a second track are, which allows a preload by rolling traffic and guarantees a final completion within a relatively short period of time.

This complex task is achieved in connection with the generic term mentioned at the outset in that the concrete trough consisting of reinforced in-situ concrete is provided below the tracks with a respective threshold support projecting from the level of the sole surface of the concrete trough and that after the alignment of the track grate, the cavities in the compacted crushed stone with a mortar suspension to form a rigid Ballast bed are filled. Due to the threshold supports protruding from the bottom surface of the concrete trough, the track grate can be placed very precisely on a defined base surface and the route can be traveled on the same track section with the conventional superstructure equipment in the form of measuring, straightening and adjusting wagons as well as the usual tamping machines, without a parallel one Neighboring tracks are required. The special wagons with the ballast are pulled over this track grate, and the concrete trough is filled with ballast as far as is necessary to be passable. No particular requirements are placed on the grain size of the ballast. All grits that are common in the DB area can be used. They are only to be installed oil-free and dust-free. A tamping machine then travels over the track that has been ballasted in this way and pulls the track grate up only 5 cm, so that the first ballast stones fall under the sleepers which are advantageously made of prestressed concrete. The raised track is then brought to an exact, predetermined height using a tamping machine using a tamping lift. In this operation, the ballast is compacted to such an extent that driving on it does not result in any changes in the track position and that a preload due to rolling traffic is possible.

The ballast masses are advantageously profiled, that is to say the ballast is distributed in such a way that it is flush with the upper edge of the threshold, if this is desired. However, it is also possible to add a few centimeters to the upper edge of the ballast bed to end below the top edge of the prestressed concrete sleeper and to allow the level of the mortar suspension to form a closed, flat surface with the surface of the ballast bed and the adjoining surfaces of the side walls.

As soon as the ballast bed with the track grate has been checked and approved by the client, the mortar suspension is filled in to form a rigid ballast bed. In contrast to the prior art, this creates a vibration system with a large mass and high internal damping, because the elasticity is removed from the superstructure and only that of the substructure is effective, which is known not only on slippery ground, but overall as a very "hard spring" can be viewed. Hard springs have the advantage of high internal damping, so that the stress caused by high-speed trains does not lead to negative vibrations.

A minimum concrete quality of B 25 is advantageously used for the concrete trough. The sleeper support has a defined bearing surface and protrudes at least 20 mm above the level of the sole surface of the concrete trough. This means that it can be handled comfortably with conventional superstructure equipment during ballast.

The concrete trough is advantageously provided on its underside for anchoring with the substructure with dowel teeth. The side walls of the concrete trough are at the level of the sole surface with openings that can be closed by plugs for drainage during the Gravel provided. Before filling the cavities in the ballast bed by filling in a mortar suspension, these openings must be closed by the plugs. Dowel-like sealing plugs made of an elastomeric material are suitable for this.

To compensate for thermal expansion, the concrete trough is provided with expansion joints that run transversely to the direction of the track and are sealed watertight with a sealant. The sealant advantageously consists of an elastomeric and polymeric joint tape, as is common in construction technology.

The superstructure obtained in this way is largely maintenance-free, but repairs may be necessary by washing the substructure or by using special forces that are not in accordance with the intended use. According to the request of the Deutsche Bundesbahn, these repairs must be carried out in as short a time as possible in order to avoid a complete closure of the route in question. In order to be able to leave the concrete trough in its original condition during such repair work and only to be able to quickly remove the ballast bed with the track grate cast into it, a release agent that does not hinder the interlocking or clawing between these is arranged between the inner surface of the concrete trough and the ballast bed (see Rheda / Sengeberg system). In the invention, this release agent is intended to be a hydraulic connection between the mortar suspension and the Prevent the inside surface of the concrete pan. This release agent will advantageously be formed from a permanent contact of the mortar suspension on the inner surface of the concrete trough, for example from a bitumen, or from a thin PE film that allows a force transmission of the ballast to the inner surface of the concrete trough, which, however, also makes contact the mortar suspension with the inner surface of the concrete pan prevented.

Due to this release agent, in the event of a repair, the section in question within the concrete trough, which consists of a layer of ballast bound by mortar suspension and the track grate, can be completely removed after cutting with a diamond saw or a similar separating device and replaced with a new track grate with new gravel and a new mortar suspension filling will.

After using the track grating and the ballast, the route can be used again by train traffic with a minimum height of 10 cm below the prestressed concrete sleepers. During this repair phase, the earth's body can re-compact under railway conditions. In the event of any settlement or displacement, the ballast bed can be corrected again by correcting it. Only then is the ballast filled with the mortar suspension. This ensures that the adjustment options of the rail fastening are not fully utilized at an early stage. Only after waiting for the settlement time can then in relative short construction time of only a few hours with, for example, a quickly hardening grout, the cavities of the ballast bed are poured or filled in the manner already described.

The level of the mortar suspension is generally level, both for such repair work and for a new installation. For this reason, the mortar suspension must be introduced in sections into the ballast bed in the case of track systems with a high cant to ensure even filling of the cavities.

According to an advantageous alternative embodiment, it is also possible to introduce ballasted gravel into the concrete trough. In this case, the mortar suspension retains a setting agent which prolongs its setting process, so that operations - aligning the track grating and compacting the ballast - can be carried out in a timely manner before the setting process of the mortar suspension begins.

In order to avoid an abrupt lowering of the track grate if the concrete trough or the substructure breaks, the ballast bed is provided with reinforcement according to an advantageous development of the invention. This reinforcement advantageously consists of several rows of steel bars that are laid in the direction of the track and run parallel to one another and penetrate the sleepers in recesses or through openings. The steel bars are endless welded together and arranged so that they cannot be damaged by the tamping machine.

• Figuren 1 bis 3 den Querschnitt durch eine auf einem Unterbau angeordnete Betonwanne während unterschiedlicher Fertigungsabschnitte der Erstellung des Oberbaus,
• Figur 4 die Querschnittsansicht gemäß den Figuren 1 bis 3 nach Verfüllung des Schotterbettes mit einer Mörtelsuspension sowie mit einer Oberflächenform in Schotterstruktur,
• Figur 5 die Querschnittsansicht der Figuren 1 bis 3 nach Verfüllung der Mörtelsuspension in das Schotterbett mit glatter Oberfläche,
• Figur 6 die Querschnittsansicht von zwei nebeneinander verlaufenden Gleisstrecken,
• Figur 7 die Draufsicht auf eine Gleisstrecke gemäß Fig. 5 mit den Querfugen und
• Figur 8 die Querschnittsansicht gemäß dem Schnitt VIII-VIII von Fig. 7,
• Figur 9 den Querschnitt von Fig. 2 mit in die Betonwanne eingesetztem Gleisrost und einer ungeschnittenen Schwelle mit Durchgangsöffnungen,
• Figur 10 den Querschnitt von Fig. 9 mit in die Betonwanne eingefülltem Schotter und in die Durchgangsöffnungen eingesetzten Stahlstäben zur Bewehrung des Schotterbettes,
• Figur 11 die Draufsicht von Fig. 10 nach Einbringung der Mörtelsuspension.

Several exemplary embodiments of superstructures produced by the method according to the invention are shown in the drawings. Show:

• FIGS. 1 to 3 show the cross section through a concrete trough arranged on a substructure during different production stages in the construction of the superstructure,
• 4 shows the cross-sectional view according to FIGS. 1 to 3 after filling the ballast bed with a mortar suspension and with a surface shape in a ballast structure,
• 5 shows the cross-sectional view of FIGS. 1 to 3 after filling the mortar suspension into the ballast bed with a smooth surface,
• FIG. 6 the cross-sectional view of two track sections running side by side,
• 7 shows the top view of a track section according to FIG. 5 with the transverse joints and
• 8 shows the cross-sectional view according to the section VIII-VIII of FIG. 7,
• FIG. 9 shows the cross section from FIG. 2 with the track grating inserted into the concrete trough and an uncut threshold with through openings,
• 10 shows the cross section of FIG. 9 with ballast poured into the concrete trough and steel bars inserted into the through openings for reinforcing the ballast bed,
• 11 shows the top view of FIG. 10 after the mortar suspension has been introduced.

On a base 1 of conventional construction with a minimum thickness of the frost-proof construction (planning protection layer and frost protection layer in the base) of at least 60 cm, a concrete trough 2 is arranged in the track direction according to arrow 3a, which is known in its U-shaped cross-sectional shape from the "Rheda" system. In contrast to the known prior art, the concrete trough made of reinforced in-situ concrete with a minimum concrete quality of B 25 below the tracks 3 is provided with a threshold support 5 protruding from the level 4a of the surface of the concrete base 4. This sleeper support 5 has a defined bearing surface 5a, which projects at least 20 mm beyond the level 4a of the sole surface of the concrete trough 2. On this sleeper support 5, the general reference number 6 is placed on the grid, which consists of the rails 3, the prestressed concrete sleepers 7 and the rail fastening 8. 1, a separating agent 10 which does not prevent the ballast bed 9a from being clamped or clawed (see FIG. 3) with this inner surface 2a is arranged on the inner surface 2a of the concrete trough 2. This release agent 10 is said to consist of one permanent contact of the mortar suspension 14 on the inner surface 2a of the concrete trough 2 preventing spraying agents, e.g. a bituminous layer, or are formed by a thin PE film, which allows a force transmission of the ballast bed 9a to the inner surface 2a of the concrete trough 2, but which is likewise not permanent Allows contact of the mortar suspension 14 on the inner surface 2a of the concrete trough 2.

On its underside 2b, the concrete trough 2 is connected to the substructure 1 by means of dowel teeth 11 in a square truncated pyramid shape (see FIGS. 1 to 5 in connection with FIG. 7).

Only after the application of the separating layer 10 to the inner surface 2a of the concrete trough 2, the track grating 6 according to FIG. 2 is placed on the sleeper supports 5.

In the side walls 2c of the concrete trough 2, openings 12 are provided for drainage at the level of the plane 4a of the sole surface with openings 12 that can be closed by elastomeric plugs 13. Through these openings 12, the concrete trough 2 can be drained during the construction phase. However, before the mortar suspension 14 according to FIGS. 4 and 5 is introduced, these openings 12 must be closed by these plugs 13 in order to prevent the mortar suspension from flowing off.

The track gratings 6 are only put on when these reinforced concrete troughs 2 have reached the necessary strength, which is usually the case after 28 days. In addition, these concrete troughs 2 are provided with expansion joints 18 (see FIG. 7) which are sealed with known elastomeric and polymeric joint tapes.

Track gratings 6 are installed in the concrete trough prepared in this way. The track gratings 6 are installed with the conventional superstructure equipment, all of which can be moved on the track. The track grate 6 consists of the rail shape specified by the client and the prestressed concrete sleepers 7 located on these rails 3. These prestressed concrete sleepers 7 also require no special pretreatment. As soon as the intended section is equipped with the track gratings 6, they are lashed. In the next step, the special wagons with the ballast 9 are then pulled over this track grating 6 and the concrete trough 2 is filled with the required ballast height, which is at least 10 cm below the prestressed concrete sleepers 7. All grits can be used in accordance with DB regulations. They are only to be installed oil-free and dust-free in order to ensure intensive contact and thus complete filling of the cavities of the ballast 9 with the mortar suspension 14.

A tamping machine travels over the track grate 6, which is so ballasted, and pulls the track grate up only 5 cm, so that the first ballast stones can fall under the sleepers. The raised track grate 6 is now with a tamping machine by one The tamping operation has been raised to the exact prescribed height. In this operation, the ballast 9 is compacted to such an extent that driving on the track grille 6 does not result in any change. The ballast 9 is profiled, that is to say it is distributed until it ends with the upper edge 7a of the prestressed concrete sleepers 7. Thereafter, the ballast bed 9a formed by the ballast 9 is checked and removed by the client. Only after this decrease, the cavities in the introduced, compacted ballast 9 are poured with the mortar suspension 14 to form a rigid ballast bed 9a and thereby filled. This mortar suspension 14 can consist of a cement suspension or another suitable hydraulic binder. The following design variants are possible when backfilling the ballast 9 and backfilling or casting the mortar suspension 14:

According to a first embodiment according to FIG. 4, the ballast bed 9a closes on its surface 9b both with the upper edge 7a of the prestressed concrete sleeper 7 and with the upper edge 2d of the two side cheeks 2c of the concrete trough 2. In this case, the ballast bed 9a is poured with the mortar suspension 14 in such a way that the ballast structure remains visible in the vicinity of the surface 9b and thus has a sound-absorbing effect.

According to a second embodiment according to FIG. 5, the ballast 9 is not installed up to the upper edge 7a of the prestressed concrete sleeper 7, but ends a few centimeters below the surface 7a of the Prestressed concrete sleeper 7. Thereby the mortar suspension 14 can be provided with a level 14a after it has been cast, which forms a closed, flat surface 2d, 7a, 14a with the surface 7a of the prestressed concrete sleeper 7 and the adjacent surfaces 2d of the side walls 2c.

In FIGS. 4 and 5, the level 14a of the mortar suspension 14 is horizontal. With such a position of the concrete trough 2, after the openings 12 have been closed by means of the plugs 13, the cavities within the ballast bed 9a to form a rigid ballast bed 9a can be completely filled with a quickly hardening grout 14. In the case of track systems with large ridges, the mortar suspension 14 is to be introduced in sections into the ballast bed 9a.

According to FIG. 6, the superstructure according to the invention requires a drainage device 15 on multi-track lines, which is either of conventional design or can consist of a ballast 16 without grout with the usual drainage channels 17. The particular advantages of the superstructure according to the invention are that all work can be carried out without using a second track as shown in FIG. 6. The installation of the track gratings 6 can be used with the existing equipment without changing the way the track builders work. Aligning the track grate 6 in the ballast bed 9a is known to all track construction companies and is carried out using state-of-the-art equipment. The bringing in the ballast 9 in the concrete trough 2 is done with the special wagons of the railway companies. Conventional crushed stone that does not require special treatment can be used. The possibilities for reworking are given until the ballast bed 9a is mortared. In contrast to the entire state of the art, this load can be preloaded by rolling traffic. When using known, fast-hardening grout, driving operation on the superstructure can be started after only 3 to 4 hours.

To transmit longitudinal and transverse forces, the superstructure is provided with dowel teeth 11, which consist of square truncated pyramids 11a on the underside 2b of the concrete trough 2, which positively engage in correspondingly designed recesses 11b of the substructure 1 (see FIGS. 1 to 5 and 7 ).

In the event of a repair, the tracks 3 including the ballast bed 9a to the separating layer 10 are cut in sections by means of diamond saws, cutting discs etc. and lifted out by known lifting devices. After renewed application of a separating layer 10, new track gratings 6 are arranged on the sleeper supports 5, the tracks 3 are welded at the joints and the ballasting of these track gratings 6 is carried out as in the new construction described. Subsequently, the ballast 9 is filled into a rigid ballast bed 9a by means of a quickly hardening grout 14. Since the tracks 3 after Filling the ballast 9 into the concrete trough 2 can already be preloaded by rolling traffic and afterwards the ballast bed 9a can be finished with the fast-curing grout 14 in a second repair phase, an advantageous second alternative solution during the repair is the possibility of already pre-grouted Insert gravel, which is then provided with a setting retarder, in order to be able to carry out the repair work for aligning and compacting before the setting process begins. Particularly in the case of short-distance repair work, this can then be carried out in a single time interval.

The method according to the invention ensures a superstructure both on bridges and in tunnels, which due to its low overall height forms a particularly advantageous alternative to the embodiments of the prior art.

In order to prevent an abrupt lowering of the track grating 6 in the event of a break in the concrete trough 2 or the substructure 1, the prestressed concrete sleepers 7 in the exemplary embodiment of FIGS. 9 to 11 are provided with a plurality of through openings 19 running parallel to one another in the track direction according to the double arrows 3a, through which the Steel rods 20 are passed through and then welded together endlessly. These steel bars 20 are shown in FIG. 11 with bold, dashed lines.

As soon as the intended section is equipped with the track gratings 6 and the reinforcement consisting of the steel bars 20, the track gratings 6 are lashed and filled with ballast in the manner described above.

This reinforcement in the form of the steel bars 20, after filling in the mortar suspension 14, brings about a composite system consisting of the track grating 6 with the prestressed concrete sleepers 7, the reinforcement formed by the steel bars 20, the ballast bed 9a and the mortar suspension 14. In this way, a superstructure with reinforced ballast bed 9a and track grating 6 is created.

If the reinforced concrete trough 2 and / or the substructure 1 break, e.g. as a result of undermining and subsequent loading, this composite system 6, 7, 9a, 14, 20 prevents an abrupt lowering of the track grating 6.

Instead of the through openings 19 in the prestressed concrete sleepers 7, recesses on the underside 7b of the prestressed concrete sleepers 7 can also occur if and insofar as the resulting notch effects are compensated for either by reinforced reinforcement of the prestressed concrete sleepers 7 themselves or by a greater thickness or by other measures.

Reference symbol list:

• Substructure 1
• Concrete pan 2
• Inner surface of the concrete trough 2 2a
• Bottom of the concrete trough 2 2b
• Sidewalls of the concrete trough 2 2c
• Surface of the side cheeks 2c 2d
• Track 3
• Track direction 3a
• Concrete base 4
• Sole surface of the concrete base 4 4a
• Threshold support 5
• Storage area of the sleeper support 5 5a
• Track grid 6
• Prestressed concrete sleepers 7
• Surface of the prestressed concrete sleepers 7 7a
• Rail fastening 8
• Gravel 9
• Ballast bed 9a
• Surface of the ballast bed 9a 9b
• Separating layer 10
• Dowel teeth 11
• square truncated pyramids 11a
• Recesses of the substructure 1 11b
• Breakthroughs 12
• Stopper 13
• Mortar suspension 14
• Level 14a
• Drainage device 15
• Ballast 16
• Drainage channels 17
• Expansion joints 18
• Through openings 19
• Steel bars 20
• Height of the ballast bed 9a below the prestressed concrete threshold 7 h

Claims (21)

1. Method for the purpose of producing a surface structure for railway lines, in particular for stretches of track subjected to high speeds and loads, comprising a reinforced concrete cradle laid in the direction of the track and having a U-shaped cross-section and comprising a bed of broken stones and track gridiron disposed therein, characterised in that the concrete cradle (2), consisting of reinforced site mixed concrete, below the tracks (3) is provided in each case with a sleeper support (5) which protrudes out of the plane (4a) of the base surface of the concrete cradle (2), and that after aligning the track gridiron (6) the hollow spaces between the deposited and compacted broken stones (9) are filled using a mortar suspension (14) for the purpose of forming a rigid bed of broken stones (9a).
2. Method according to claim 1, characterised in that the concrete cradle (2) comprises a grade of concrete which is at least B 25.
3. Method according to claim 1 or 2, characterised in that the sleeper support (5) is provided with a defined bearing surface (5a) and protrudes at least 20mm beyond the plane (4a) of the base surface of the concrete cradle (2).
4. Method according to any one of the claims 1 to 3, characterised in that between the inner surface (2a) of the concrete cradle (2) and the bed of broken stones (9a) is disposed a separating means which does not restrict the manner in which the inner surface (2a) and the bed of broken stones (9a) clamp and mesh together.
5. Method according to claim 4, characterised in that the separating means is formed from a spray means (10), for example bitumen, which prevents any permanent contact of the mortar suspension (14) on the inner surface (2a) of the concrete cradle (2) or is formed by a thin PE-film which permits a transfer of force from the bed of broken stones (9a) to the inner surface (2a) of the concrete cradle (2).
6. Method according to any one of the claims 1 to 5, characterised in that the concrete cradle (2) is provided on its underside (2b) with a dowel pin toothing (11) for the purpose of being anchored to the lower structure (1).
7. Method according to any one of the claims 1 to 6, characterised in that the lateral faces (2c) of the concrete cradle (2) are provided at the height of the base surface with through-openings (12), which can be closed by elastomer stoppers (13), for the purpose of providing water drainage.
8. Method according to any one of the claims 1 to 7, characterised in that the concrete cradle (2) is provided with expansion joints (18) which extend in a transverse manner with respect to the direction of the track (arrow 3a) and are sealed in a watertight manner using a sealing means.
9. Method according to claim 8, characterised in that the sealing means consists of an elastomer and polymer joint band.
10. Method according to any one of the claims 1 to 9, characterised in that the track grid iron (6) comprises prestressed concrete sleepers (7).
11. Method according to any one of the claims 1 to 10, characterised in that the bed of broken stones (9a) terminates both at the surface (7a) of the prestressed concrete sleeper (7) and at the upper edge (2d) of the two lateral faces (2c) of the concrete cradle (2).
12. Method according to any of the claims 1 to 10, characterised in that the surface (9b) of the bed of broken stones (9) ends a few centimetres below the surface (7a) of the prestressed concrete sleeper (7) and after pouring in the mortar suspension (14) its level (14a), together with the surface (7a) of the prestressed concrete sleeper (7) and the adjacent surfaces (2d) of the lateral faces (2c), forms a closed planar surface (2d, 7a, 14a).
13. Method according to any one of the claims 1 to 12, characterised in that the height (h) of the bed of broken stones (9a) below the prestressed concrete sleeper (7) is at least 10 cm.
14. Method according to any one of the claims 1 to 13, characterised in that the level (14a) of the mortar suspension (14) is aligned in a horizontal manner.
15. Method according to any one of the claims 1 to 13, characterised in that in the case of track installations comprising greater cambers, the mortar suspension (14) can be poured in stages into the bed of broken stones (9a).
16. Method according to any one of the claims 1 to 15, characterised in that the mortar suspension (14) consists of a rapidly hardening pourable mortar.
17. Method according to any one of the claims 1 to 15, characterised in that during repair work the mortar suspension (14) contains a retarding agent which prolongs its setting process.
18. Method according to any one of the claims 1 to 17, characterised in that the bed of broken stones (9a) is provided with a reinforcement (20).
19. Method according to claim 18, characterised in that the reinforcement consists of several rows of steel bars (20) which are laid in the direction of the track (arrow 3a) and extend parallel with each other.
20. Method according to claim 19, characterised in that the steel bars (20) penetrate the sleepers (7) in recesses or in through-going orifices (19).
21. Method according to any one of the claims 18 to 20, characterised in that the steel bars (20) are welded together so as to be continuous.

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