EP0952307B1 - Method for the construction of a structure under an embankment supporting a railway track or a roadway - Google Patents

Abstract

The procedure is carried out by constructing or laying a flat guide platform (2) on at least one side of the embankment excavation to support a concrete tunnel structure or frame (13) and connecting it to traction cables (6) inserted through channels in the platform. One end of each cable is connected to a fixed anchoring point (12) on the platform, while the other is connected to a power cylinder (21) which enables the structure to be slid into position inside the embankment excavation on a layer of a lubricating agent between the structure's base slab (14) and platform.

Description

The present invention relates to a method for the realization of a passage or tunnel reserved for the circulation of pedestrians or vehicles under a railway line or a road or motorway pavement in activity, which requires only a limited interruption in time traffic on this lane, the structure defining the passage to be built being prefabricated, if necessary made next to the lane before it is momentarily cut to allow the excavation of the ground forming the support slope of this lane , said work being then set up in the excavation thus created before the road or the roadway is reconstituted on the top of this work.

The invention is more particularly a method which, once the excavation cleared after severing the track, to bring the work under the location of the latter in extremely short time, while allowing a remarkable accuracy of its positioning the sub-layers or the ballast are then reconstituted on the structure before the track is reformed, allowing the immediate resumption of traffic.

More particularly, the invention relates to a construction method in which the work to be done in under the track consists of a means of one or two frames, hollow and concrete, developed in situ, the frame being arranged in the first case on one side of the slope carrying the track and in the case of two homologous frames symmetrically to each other on each side of the median plane of this slope, parallel to the track, the single frame being placed transversely in the excavation or the two frames meeting in the median plane so as to ensure continuity of passage under the path from one frame to another.

The European patent EP-A-0 611 848 is known on behalf of the applicant, a process known as autoripage, allowing the supply of a work developed in situ reinforced concrete through a slope supporting a railway, an active road or highway pavement.

This method uses, for moving bridges or structures developed in-situ reinforced concrete, at least one base plate support and guide for a concrete frame. The frame is carried by the raft and is provided laterally with anchor points for traction cables. The traction cables are secured at the front of the guide raft to at least one fixed anchoring point, while the other end is engaged with cylinders carried by the frame, so that the tensile force exerted on the cables by the jacks is reflected, as a result of reaction, a sliding of the frame on the floor and then on the ground.

The main disadvantage of this method lies particularly in the fact that it is insufficient to move large volume structures. Indeed, the anchoring points which are located laterally and at the front of the guide raft in a spade, tend to bend and tear from the ground under the effect of the traction of the jacks and because of the friction important between the contacting faces respectively of the frame, the floor and the floor.

Also known from British Patent GB 1 491 100, a method of elevating a structure employing a system similar to an air cushion. It is actually a bladder that is filled with a fluid that, under the effect of pressure, causes the swelling of the bladder and the elevation of the work. In this method, there is no injection of fluidifying agent under the frame of the frame to be transported, to facilitate its sliding.

The present invention aims to overcome these disadvantages, by proposing a method that allows on the one hand, to distribute the tensile force on multiple anchor points judiciously distributed at the end of the front of the guide raft in at least one spade buried in the ground perpendicular to the axis of traction, and secondly, advantageously, to distribute with the aid of a fluid mattress, contained between the slab of the structure and the sole of the raft or the ground, the pressure of this work on the support.

For this purpose, the subject of the invention is a process as defined by appended claim 1.

In a preferred mode of implementation of the method according to the invention, the flat guide bed is arranged so as to make it comprise at least one boss or solid constituting the passive anchor point of the traction cables, this boss being disposed in the vicinity of the end of the guide raft directed towards the inside of the excavation, at the level of at least one transverse spade.

Similarly, there is arranged at the rear of the base of the frame, at least one boss or massive constituting the active anchor of the jacks which cooperate with the traction cables.

Under these conditions, the method consists in associating via the passive and active anchoring points, each structure supported by the base of the frame to at least one or more parallel cables, extending below the latter at the level of longitudinal passages made within the guide raft.

According to a particular characteristic, the anchoring protrusions of the cables are formed in the front part of the guide raft, closer to the sides of the excavation in the embankment, the traction cylinders being mounted on the base of the frame.

Advantageously, the active anchoring bosses comprise, at the level of the zones of attachment of the cylinders, orifices whose penetration axis is inclined relative to the horizontal by an angle α, by means of deflectors, so as to deflect the traction cables towards the bottom of the frame raft, in the grooves of reservation of the guide raft.

Advantageously, in a similar manner, the passive anchor bosses located in the "spade" zone of the guide raft, at the zones of fastening of the ends of the cables, comprise orifices whose penetration axis is inclined relative to horizontally at an angle β, so as to deflect the traction cables running in the guide raft to the "spade" zone.

Preferably, the cables used are multi-wire cables, the strands of which are secured at one of their ends to a bearing plate abutting the opposite face of the anchoring boss.

• la figure 1 est une vue en perspective d'un dispositif permettant la mise en oeuvre du procédé, objet de l'invention ;
• la figure 2 est une vue en coupe et en élévation latérale d'un dispositif pour la mise en oeuvre du procédé, objet de l'invention ;
• la figure 3 est une vue en coupe et en élévation frontale de la figure 2 ;
• la figure 4 est une vue en coupe et en vue de dessus du radier du cadre ;
• la figure 5 est une vue en coupe et en élévation latérale, à plus grande échelle, du radier du cadre ;
• la figure 6 est une vue en coupe et en élévation latérale, à plus grande échelle, d'un autre point de détail du radier du cadre ;
• la figure 7 est une vue en coupe et en élévation frontale d'un dispositif pour la mise en oeuvre du procédé, dans lequel les saignées de réservation pour le passage des câbles sont réalisées dans le radier du cadre ;
• la figure 8 est une vue de détail, en coupe et en élévation frontale, des saignées de réservation réalisées dans le radier du cadre.

Other features of a method for the construction of structures under a railway line and means for implementing this method will become apparent from the following description of an exemplary embodiment, given for information only and not limiting, with reference to the accompanying drawings in which:

• Figure 1 is a perspective view of a device for carrying out the method, object of the invention;
• Figure 2 is a sectional side elevational view of a device for carrying out the method object of the invention;
• Figure 3 is a sectional and front elevational view of Figure 2;
• Figure 4 is a sectional view and a top view of the base of the frame;
• Figure 5 is a sectional view and side elevation, on a larger scale, of the base of the frame;
• Figure 6 is a sectional and side elevational view, on a larger scale, of another detail point of the base of the frame;
• Figure 7 is a sectional front elevational view of a device for carrying out the method, wherein the reservation grooves for the passage of the cables are made in the base of the frame;
• Figure 8 is a detail view, in section and in front elevation, of the reservation grooves made in the base of the frame.

According to the invention, the realization of such a passage is carried out as follows, the example given below being relative to the implementation of a passage consisting of two prefabricated concrete frames, homologous and arranged symmetrically on both sides of the slope, these frames meeting substantially in the median longitudinal plane of the slope extending parallel to the track. Of course, the method applies just as well when the passage to be made is constituted by means of a single frame which extends entirely through the slope to form alone the passage in question.

Firstly, two support and guide rafts 1 are built on either side of the embankment, these rafts being arranged opposite one another with respect to the median plane of the track. .

Each guide raft 1 consists of a concrete flat sole 2, preferably cast in situ and having projecting parts such as extending under this sole 2 to form spades 3 for immobilizing the raft 1 in the ground . Where appropriate, the slab is associated with tie rods whose one end is secured to the edge of the slab and the other, which is buried in the ground, is locked relative to the latter being embedded in a solid mass of concrete. On its lateral sides, the sole 2 comprises flanges 4 whose role will be specified later.

The sole 2 is provided with a plurality of reservation grooves 5 which are adapted to allow the passage of traction cables 6. These reservation grooves 5 are arranged along the longitudinal axis of the guide raft 1, they allow the horizontal path traction cables 6 between the two ends 7, 8 facing deviators 9, 10 respectively from active anchoring points 11 and passive 12.

In a second step, on each guiding slab 1 thus produced and immobilized on the ground, there is disposed a hollow frame 13 forming the framework of the concrete structure, generally of rectangular cross section and comprising a lower slab 14, on the sides 15 and an upper slab 16, parallel to the lower slab 14, the width of the frame 13 being substantially equal to that which separates, on the guide slab 1, the flanges 4 thereof, so that once the frame cast on the guide raft 1, this frame 13 can slide on the latter 1, this sliding can be facilitated in particular by an injection between the sole 2 and the slab 14, between their opposite faces, a lubricating agent , in particular a bentonite slurry or other similar product, providing a lubrication that may be useful during the relative displacement of the frame 13 on the guide slab 1, and then on the ground, in front of the slab as and when as the frame 13 moves away from it, as explained hereinafter.

The lubrication agent injection wells open into a plurality of Ω sections placed in directions substantially transverse to the direction of movement of the structure.

According to an advantageous characteristic of the invention, an annular belt 17 is produced on the slab 14 of the slab of the frame 13, at the level of the face opposite the guide slab 1. The latter is intended to receive a bladder 18 or chamber preferably made of a deformable material, in particular of the plastic material type, under the action of a fluid under pressure.

Thus, during the casting process of the lower slab 14 of the slab of the frame 13 of the concrete structure, the material reserve forming the annular belt 17 is filled by a chamber 18 which is filled with a fluid under pressure. incompressible type of water, so as to expand it in the volume of the annular belt 17 and to form a mattress that will be able to withstand the compressive forces during the pouring of concrete from the structure on the base of the frame 13.

During the phase of shifting of the raft of the frame 13 relative to the guide raft 1, the fluid contained in the bladder 18 is driven out and is replaced by a gaseous fluid under pressure (compressed air).

According to another characteristic, the face of the bladder 18 facing the face of the guide raft 1 has a plurality of raised areas 19, so as to form a lip which retains the fluid which is injected between the sole 2 and the slab lower 14.

It is thus possible, thanks to this bladder 18 filling the annular belt 17, to contain between the sole 2 and the lower slab 14, a substantially constant thickness of a fluid mattress of a lubricating agent, intended to support the structure on the guide raft 1, then on the ground, during the sliding of the structure, and without risk of lateral leakage of lubricating agent given the presence of the lips.

The pressure of the structure on the guide raft 1, then on the ground, taking into account the order of magnitude of the facing surfaces, is maintained, thanks to this device, in a very reasonable range, of the order of 0.3 to 1.5 bar, which allows the lifting of the structure for a fluid injection pressure, on the one hand inside the chamber 18 (of the order of 1.5 to 2 bars), and secondly between the lower slab 14 and the sole 2, the intensity of the injection pressure of the lubricating agent being of the order of 0.3 to 1.5 bar.

In order to prevent the lubrication agent from escaping through the reservation grooves 5 made in the guiding raft 1, in the intersecting zones between the reservation grooves 5 and the injection wells 5 the lubricating agent, a plate 20 partially closing the section in Ω at this level.

The cables 6 may, depending on the case, be manufactured on site or may be prefabricated and brought already trained on site. The lateral sides 15 of each frame 13 may optionally also comprise external bosses 11, arranged above the flanges of the guide raft 1 when the frame 13 rests on it, being in these conditions substantially vis-à- screw and in the extension of the passive anchoring bosses 12 of the guide raft 1, provided at the end of the flanges at the end of the slab facing the slope.

The active bosses 11 of the frame 13 are arranged so as to allow the mounting and the support of hydraulic jacks 21, intended to cooperate with traction cables 6 such that each of the possible lateral cables and cables located between the base of the frame 13 and the guide raft 1, respectively along the lateral sides and the front edge of the frame, having an end fixed on the one hand to the corresponding passive anchor 12 buried in the ground at the spade 3 and being engaged with secondly with the jack 21 so that the tensile force on the cable 6 exerted by this jack 21 causes, by reaction on the frame 13, a corresponding displacement of the latter vis-à-vis the guide slab 1 in direction of the slope.

The cables 6 are multi-wire cables, formed of a plurality of strands arranged such that, at the end of the cable in the passive anchor 12, they develop in a recess thereof to be fixed to the means of locking keys on a support plate 22, ensuring a suitable distribution of the forces created by the corresponding traction cylinder 21.

The zone of expansion of the cable 6 inside an orifice 23 made in the passive anchor 12 is effected within a trumpet 24. The main axis of this orifice 23 is inclined by an angle β relative to the horizontal axis, this angle being between 5 and 15 ° and preferably close to 10 °.

Similarly, at the bosses of the frame 13 constituting the active anchoring points 11, it is expected that each orifice 24 through which each pulling cable 6 opens, is inclined at an angle α with respect to the horizontal axis, this angle being between 5 and 15 ° and preferably close to 10 °.

In addition each of the orifices 23, 24 made within the active anchoring points 11 and passive 12 is provided with a deflector 23 '. This deflector 23 'is made from a tube, in particular metal, which is additionally bent.

It thus forms a guiding sheath for each of the traction cables 6 between the anchoring points 11, 12 and the reservation grooves 5 made in the guide raft 1.

The frame 13 cast on its guide raft 1, with a similar arrangement on each side of the slope in the example especially considered, being again recalled that the same process can be implemented with a single frame and a single slab laid out of one side of the embankment, we proceed then to the momentary sectioning of the track and to the realization across the embankment of a excavation whose dimensions transversely are substantially those of the frames which, once put in place in this excavation, will delimit the passage realized under the track.

Each of these frames 13 is progressively and mutually ripened towards each other on the guiding rafts 1 which support them, until such time as these cables, which run horizontally within the reservation grooves 5, meet in the median plane of the embankment, ensuring continuity of passage underlayers or ballast on top of the upper slab 16 of each frame 13 can be quickly replaced, before the track is reconstituted to allow recovery traffic that was only interrupted during the skipping operations of frames 13, as indicated above.

This ensures the realization of a passage under a railway or if necessary a roadway or other, in a simple, fast and efficient way, with a time traffic interruption on this route as limited as possible. The guidance of the frames and their sliding on the two rafts is made very easy by the design of the latter and in particular the presence of the side edges they contain, allowing to obtain a very precise positioning of the frames towards each other as and when they come together. In addition and as already stated, their sliding may be facilitated if necessary by proper lubrication of the sole of the slab and the lower slab frames, but in any case without requiring the use through the excavation of sills or other rails support as used in conventional solutions and whose implementation is long and delicate, and therefore requires a greater interruption of traffic.

In addition, since the tensile forces of the cylinders on the cables 6 are distributed in a transverse plane of the spade 3, there is more risk of tearing and bending thereof.

It is thus possible, thanks to this method, to set up prefabricated concrete structures of considerable mass, because of the joint action of a plurality of action points having to move the structure and a joint annular which maintains between the sole 2 and the slab 14 a mattress of a lubricating agent supporting the weight of the structure during its sliding, the force exerted on the frame 13 being exercised in a distributed manner on a sill beforehand buried in the ground.

Note also that, the ground pressure due to the frames 13 sliding on their guide rafts 1 is less than that created by the mass of soil removed in the excavation, the risk of soil compaction as they are encountered in a process of shifting frames on longrins previously made across this excavation, are eliminated, which allows a safer implementation of the frames.

Of course and as it follows from the foregoing, the invention is not limited to the example of implementation more specifically described above with reference to the accompanying drawings; on the contrary, it embraces all the variants falling within the scope of the following claims, in particular when the passage to be arranged under the track is formed by means of a single frame and no longer as above with the aid of two counterparts in the median plane of the embankment in the middle of the excavation. Also, as an alternative embodiment, provision can be made for the traction cables to travel within the reservations provided in the base of the frame rather than in the guide raft, these cables going down into these reservations via diverters. positioned transversely with respect to the guide raft. This variant embodiment is illustrated in FIGS. 7 and 8.

Particularly, as illustrated in FIG. 8 which represents a detail of construction of the passage of the cables 6 within a groove made in the base of the frame, it may be noted that this guide groove in the base of the frame 13 is formed by the assembly of angles previously secured to the guide bed 1, using plastic screws which will be cut during the movement of the work, these angles being coated with a metal section which is welded to them after having walked in the housing delimited by the two lateral angles, the strands of the cables 6.

Claims (6)

1. Method of constructing a structure beneath an embankment supporting a railway track or a roadway, consisting in temporarily cutting the track/roadway in line with the intended location in the embankment supporting the track/roadway for the passage that is to be produced, in digging a trench by excavating the ground in that location, in previously producing or arranging, on at least one side of the trench, at least one flat guide bed (1) supporting at least one bed of the concrete frame (13) of the structure, in arranging traction cables (6) which are each fixedly connected at one end to a fixed anchoring point (12) and the other end of which is in engagement with at least one traction jack (21) carried by the bed of the frame (13) in the region of an active anchoring point (11), in such a manner that the pull exerted on the cables (6) by the jacks (21) is converted, as a result of the reaction on the passive anchoring points (12), into a thrust effect on the bed of the frame (13), which gradually slides on the guide bed (1), then on the bottom of the trench, in order directly to ensure its penetration into said trench, in front of said guide bed (1),
   characterised in that the cables (6) are located beneath the frame (13) inside clearance grooves (5) formed in the guide bed (1) or in the bed of the frame (13), in that the passive anchoring points (12) are distributed at the front end of the guide bed (1) in the width of at least one spade (3) which is connected to said bed and is buried in the ground perpendicular to the axis of traction, and, in the buried portion of that spade (3), in that the active anchoring points (11) are distributed over the width of the frame (13), and in that curved deflectors (9, 10) are incorporated into the active anchorages (11) and passive anchorages (12), which deflectors constitute guide sheaths for each of the traction cables (6) between the anchoring points (11, 12) and the clearance grooves (5).
2. Method according to claim 1, characterised in that an annular belt (17) containing a bladder (18) which is deformable under the action of a pressurised fluid is provided within a lower plate (14) of the concrete structure and facing the base (2) of the guide bed, then the bladder (18) is filled with a fluid in such a manner as to form a joint between the base (2) of the guide bed (1) and the lower plate (14), the dilated bladder (18) maintaining, between the lower plate (14) and the base (2), a mattress of a lubricating agent previously introduced through the plate (14), during the sliding of the frame (13) of the structure relative to the guide bed (1), then on the ground.
3. Method according to either claim 1 or claim 2, characterised in that there are provided within bosses forming the active anchoring points (11) orifices (24) which open inclined by an angle α relative to the horizontal axis, that angle being from 5 to 15°.
4. Method according to claim 3, characterised in that the orifice (24) is inclined by an angle α close to 10°.
5. Method according to any one of the preceding claims, characterised in that there are provided within bosses forming the passive anchoring points (12) orifices (23) which open inclined by an angle β relative to the horizontal axis, that angle being from 5 to 15°.
6. Method according to claim 5, characterised in that the orifice (23) is inclined by an angle β close to 10°.