EP0611848A1 - Process for the construction of structures under an embankment of a railroad or the like - Google Patents

Abstract

Process for constructing a structure under an embankment of a railway (1) or of a roadway, consisting in temporarily cutting the track (road) (1) in line with the intended location in the embankment (2) of this track for the passage to be produced, and in digging a ditch (25) by excavating the ground at this location, characterised in that it consists in manufacturing or arranging, in advance, on at least one side of the ditch (25), optionally in both of the sides of this ditch, on either side of the embankment and opposite each other, at least one flat support and guide reinforcement (3) for a hollow concrete frame (13), the frame (13) being borne by the reinforcement (3) outside the ditch (25), in fitting, parallel to the side edges of the hollow frame (13), at least one traction cable (20), this cable (20) being solidly attached at one end to a fixed anchoring point (12, 28), while the other end engages with a jack (actuator) (19) borne by the frame (13), so that the traction force exerted on the cable (20) by the jack (19) is converted, owing to the reaction on the anchoring boss (12, 28), into a thrust effect on the frame (13), which progressively slides over the reinforcement (3) then over the ground in the ditch (25), in order to cause it to penetrate directly into this ditch, in front of the reinforcement (3).

Description

The present invention relates to a method for making a passage or tunnel reserved for the movement of pedestrians or vehicles under a railroad or a working road or motorway roadway, which requires only a time-limited interruption of traffic on this track, the structure defining the passage to be constructed is prefabricated, if necessary carried out next to the track before it is temporarily cut to allow the excavation of the land forming the embankment of this track , said structure then being placed in the excavation thus created before the track or the roadway is reconstructed on top of this structure.

The invention relates more particularly to a process which allows, once the excavation cleared after sectioning the track, to bring the structure under the location of the latter in extremely short time, while allowing remarkable precision of its positioning , the land then being reconstituted on the structure before the track is reformed, allowing immediate resumption of traffic.

More particularly still, the invention relates to a construction method in which the structure to be placed under the track is formed by means of one, or even two frames, hollow and concrete, prefabricated, 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 of 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 else the two frames meeting in the median plane so as to ensure the continuity of the passage under the track from one frame to another.

To this end, the process considered, consisting of temporarily cutting the track to the right of the location provided in the embankment supporting this track for the passage to be carried out, and carrying out an excavation by excavating the ground in this location, is characterized in that it consists in previously manufacturing or disposing, on at least one side of the excavation, if necessary in each of the two sides of the latter on either side of the embankment and opposite it one from the other, at least one flat support and guide raft for each hollow concrete frame, the frame being carried by the raft outside the excavation, to be put in place, parallel to the lateral sides of the hollow frame , at least one traction cable, this cable being secured to one end of a fixed anchoring point while the other end is engaged with a jack carried by the frame, so that the traction force exerted on the cable through the jack translates, pa r following the reaction on the anchoring boss, by a pushing effect on the frame which gradually slides on the raft then on the ground of the excavation, to directly insure its penetration in this one, in front of the raft.

The process according to the invention thus consists in creating between the raft carrying the frame, the traction cables and the jacks which exert a force on these cables to move the frame with respect to the raft, a closed system of forces, allowing progressive and autonomous advance of the frame in the search until it is finally installed, by completely crossing this excavation in the embankment before the track is then reconstituted on top of the frame, or in the case of two symmetrical frames previously arranged on either side of this excavation , their mutual rapprochement until the moment when these executives meet in the middle of the work.

In particular, the method according to the invention makes it possible to eliminate the prior production in the excavation, on the ground thereof, of beams transverse to the direction of the track extending through the slope and on which, according to the conventional process, the frame is slid, the production of these stringers, to give them a suitable straightness, being complex, long and expensive.

In a first embodiment of the method according to the invention, the flat base is arranged so as to make it comprise at least one boss constituting the anchoring point of the traction cable, this boss being arranged in the vicinity of the end of the raft facing the excavation.

In another embodiment, the anchoring point is constituted by means of at least one solid mass, immobilized in the ground, disposed on the other side of the excavation relative to the raft, the traction cable extending through the excavation.

Under these conditions and whatever the variant more particularly chosen, the method consists in associating each frame with at least two first parallel cables, extending respectively along each of the lateral sides of this frame. However and as a variant, each of the frames can be made to cooperate with four parallel cables, two to two symmetrical on either side of the median plane of the frame, the first two cables being arranged along its lateral sides outside the frame, while the second two freely pass through longitudinal passages provided inside the lower slab of the frame.

In particular and as the case may be, two anchoring points constituted by bosses provided on the raft on each side of the frame for a pair of parallel cables, and two other anchoring points constituted by two solid masses immobilized in the ground for the other pair of cables. In particular, the cables of one of the pairs may be the first cables and those of the other pair the second, or vice versa.

Preferably, the frame is associated with two first parallel cables, extending respectively along each of the lateral sides of this frame. According to a variant, however, the frame can cooperate with four parallel cables, two to two symmetrical on either side of the median plane of the frame, the first two cables being arranged along its lateral sides outside the frame, while the two seconds pass freely through longitudinal passages provided inside the lower slab of the frame.

According to a particular characteristic, the cable anchoring bosses are formed in the front part of the slab, as close as possible to the sides of the excavation in the slope, the traction jacks being mounted in the rear part of the frame supported by this slab.

According to another characteristic, the raft comprises a sole, of rectangular profile, the width of which is substantially equal to that of the frame.

Advantageously, the raft is immobilized on the ground, on the side of the embankment supporting the track, by means of projecting parts suitable for being buried in the ground so as to constitute "spades" for anchoring this raft. The case where appropriate, the raft is associated with anchor rods, one end of which is secured to the edge of the raft opposite the slope and the other end of which is embedded in a mass of concrete buried in the ground.

According to yet another characteristic, the frame, made of concrete, laterally comprises external bosses allowing the mounting of the traction jacks, each external boss provided on the frame being disposed substantially opposite an anchoring boss of the apron carrying this frame. .

Preferably, the cables used are multi-wire cables, the strands of which are integral at one of their ends with a bearing plate in abutment on the opposite face of the anchoring boss.

Preferably also, each raft has laterally raised edges for guiding the sliding frame thereon under the effect of the traction cables. Advantageously and to facilitate this sliding if necessary, a layer of bentonite or other similar material is permanently injected between the lower face of each frame and the upper face of the raft, capable of lubricating the facing surfaces mutually.

• La Figure 1 est une vue schématique en perspective d'un talus de support d'une voie ferrée et à travers lequel est aménagée une fouille pour la mise en place d'un ouvrage délimitant un passage sous la voie, au moyen du procédé selon l'invention.
• La Figure 2 représente une vue en perspective d'un radier plat, construit sur un des côtés du talus en regard de la fouille et sur lequel est mis en place un cadre creux, propre à constituer selon le cas le passage à réaliser ou seulement une moitié de ce passage, ce cadre étant alors associé à un cadre homologue symétrique.
• Les Figures 3 et 4 sont des vues respectivement en coupes longitudinale partielle et transversale d'un radier et du cadre porté par celui-ci.
• Les Figures 5 et 6 sont des vues à plus faible échelle, respectivement en coupe longitudinale et en coupe transversale du passage réalisé sous la voie, permettant de mieux expliciter les diverses étapes de mise en oeuvre du procédé.
• La Figure 7 est une vue en perspective analogue à la Figure 2, relative à une autre variante de réalisation.
• La Figure 8 illustre un perfectionnement apporté au radier de support du cadre, pour améliorer sa résistance aux efforts de traction exercés sur ce cadre par les divers câbles. Sur la Figure 1, la référence 1 désigne une voie ferrée d'un type en lui-même classique, construite à la partie supérieure d'un talus 2, à travers lequel doit être réalisé un passage pour piétons ou véhicules, ce passage s'étendant sous la voie.

Other characteristics of a process for the construction of works under a railway track and of the means for the implementation of this process will become more apparent from the following description of an exemplary embodiment, given by way of indication and not limiting, with reference to the accompanying drawings in which:

• Figure 1 is a schematic perspective view of an embankment supporting a railroad track and through which is arranged a dig for the establishment of a structure delimiting a passage under the track, by means of the method according to the invention.
• Figure 2 shows a perspective view of a flat raft, built on one side of the embankment facing the excavation and on which is placed a hollow frame, suitable to constitute, as the case may be, the passage to be carried out or only a half of this passage, this frame then being associated with a symmetrical homologous frame.
• Figures 3 and 4 are views respectively in partial longitudinal and transverse sections of a raft and the frame carried by it.
• Figures 5 and 6 are views on a smaller scale, respectively in longitudinal section and in cross section of the passage made under the track, to better explain the various stages of implementation of the method.
• Figure 7 is a perspective view similar to Figure 2, relating to another alternative embodiment.
• Figure 8 illustrates an improvement made to the frame support raft, to improve its resistance to the tensile forces exerted on this frame by the various cables. In Figure 1, the reference 1 designates a railroad of a type in itself conventional, built at the top of an embankment 2, through which must be made a passage for pedestrians or vehicles, this passage s' extending under the track.

According to the invention, the realization of such a passage is carried out in the following manner, the example given below relating to the implementation of a passage consisting of two precast concrete frames, homologous and arranged symmetrically on either side of the slope, these frames substantially joining in the median longitudinal plane of this slope extending parallel to the track. Of course, the method applies equally well when the passage to be made is constituted by means of a single frame which extends entirely across the slope to form the passage in question on its own.

As a first step, two support and guide rafts 3 are constructed on either side of the slope 2, only one of which is shown in FIGS. 1 to 3, these rafts being arranged facing one of the another vis-à-vis the median plane 4 of channel 1, as shown schematically in Figures 5 and 6.

Each raft 3 (Figure 1) consists of a flat concrete base 5, preferably cast in situ and comprising projecting parts such as 6 extending under this sole to constitute spades for immobilizing the raft in the ground 7. Where appropriate, the raft is associated with anchor rods 8, one end 9 of which is secured to the edge of the raft and the other of which, which is buried in the ground, is blocked with respect to the latter by being submerged in a concrete block 10. On its lateral sides, the sole 5 includes flanges 11 whose role will be explained below. In its front part, facing the slope 2, the slab 3 comprises, at the end of each rim 11, an anchoring boss 12.

In a second step, there is on each guide raft 3 thus produced and immobilized on the ground, a hollow frame 13 (see FIGS. 2 and 3), generally of rectangular cross section and comprising a lower slab 14, lateral sides 15 and 16 and an upper slab 17, parallel to the slab 14, the width of the frame 13 being substantially equal to that which separates, on the raft 3, the flanges 11 thereof, so that, once the frame 13 is put in place on the raft, this frame can slide on the latter, this sliding can be facilitated in particular by an injection between the sole 5 and the slab 14, between their opposite faces, of a bentonite grout or other similar product, ensuring a possibly useful lubrication during the relative displacement of the frame on the raft, then on the ground in front of the raft as the frame moves by moving away from it, as explained below after.

The frames 13 can, depending on the case, be manufactured on site or even be prefabricated and brought already formed on the site. The lateral sides 15 and 16 of each frame 13 also have external bosses 18, disposed above the flanges 11 of the raft 3 when the frame rests thereon, in these conditions being substantially opposite and in the extension of the anchoring bosses 12 of this raft, provided at the end of the flanges, at the end of the raft facing the slope 2.

The bosses 18 of the frame are arranged so as to allow the mounting and the support of hydraulic jacks 19, intended to cooperate with traction cables such as 20, each of these cables, along the lateral sides 15 and 16 of the frame, having a end fixed to the corresponding boss 12 and being engaged with the jack 19 so that the tensile force on the cable exerted by this jack causes, by reaction on the frame, a corresponding displacement of the latter vis-à-vis the apron in the direction of the slope 2.

Advantageously and as shown schematically in Figure 4, the cables 20 are multi-wire cables, formed of a plurality of strands 21 arranged so that, at the end of the cable in the boss 12, they flourish in a recess 22 thereof to be fixed by means of locking keys 23 on a support plate 24, ensuring an adequate distribution of the forces created by the corresponding traction cylinder 19.

The frame 13 being placed on its slab 3, with a similar arrangement on each side of the slope 2 in the example more especially considered, being again reminded that the same process can be implemented with a single frame and a slab single arranged on one side of the slope, one then proceeds to the momentary sectioning of the track 1 and to the realization through the slope of a dig 25 whose transverse dimensions are substantially those of the frames 13 which, once put in place in this excavation, will delimit the passage made under the track.

Figures 5 and 6 make it easy to understand how the positioning of the two frames 13 is carried out on each side of the slope in the excavation 25, each of these frames being gradually and mutually ripped towards each other on the rafts 3 which support them, until these cables meet in the median plane 4 of the slope 2, ensuring the continuity of the passage, the ground on top of the upper slab 17 of each frame being able to be quickly replaced, before the channel 1 is reconstituted so as to allow the resumption of the traffic which was only interrupted during the operations of shifting of the frames 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 manner, with a time of interruption of traffic on this track 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 lateral flanges which they comprise, making it possible to obtain a very precise positioning of the frames towards each other. as they come together. Furthermore and as already specified, their sliding can be if necessary facilitated by suitable lubrication of the base of the raft and the lower slab of the frames, but in all cases without requiring the use through the excavation of sills or other supporting rails such than used in conventional solutions and whose implementation is long and delicate, and consequently requires a greater interruption of traffic.

Note also that, the ground pressure due to the frames sliding on their rafts being lower than that created by the mass of earth removed in the excavation, the risks of compaction of the soil as they are encountered in a process of shifting the frames on sills previously made across this excavation are eliminated, which allows a more secure installation of the frames.

In addition, if as a general rule the use of cables 20 arranged along the lateral sides 15 and 16 of each frame is sufficient to ensure satisfactory shifting of the latter, provision may be made according to other variants to improve the distribution of forces. pushing on the frames using other traction cables, for example such as 26 (see Figures 2 and 3), arranged in holes provided in the lower slab 14 of the frame 13 and anchored at the front of the slab 3 on abutment plates 27, arranged so as not to hinder the advance of the frame in the excavation 25.

Of course and as follows from the above, the invention is not limited to the example of implementation more particularly described above with reference to the accompanying drawings; on the contrary it embraces all the variants coming within the scope of the claims below, in particular when the passage to be arranged under the track is formed by means of a single frame and no longer as above using two homologous frames joining in the median plane of the slope in the middle of the excavation.

Thus and as shown in Figure 7, one can not only provide for the implementation of a single frame 13 to slide by sliding on its raft 3 inside the excavation 25 formed in the slope 2, but arrange the anchor points of the traction cables 20 and, where appropriate, 26 (here not shown), no longer on the front part of the raft but on the other side of the slope relative to the latter.

In this variant, the bosses provided in the previous example in the front part of the raft 3, are replaced by massifs 28, previously put in place in the ground 7, in line with and in the extension of the raft, but opposite to this vis-à-vis the location of the raft.

These solid masses 28 consist in particular of two parallel bars, respectively 29 and 30, buried in the ground and provided at their upper part which is flush therewith with means for attaching the end of the cables 20, possibly 26, which allow , in the manner already explained, to exert on the frame 13 its progressive advance inside the excavation 25 by sliding on the raft 3. These bars 29 and 30 can advantageously be immobilized in position by means of tie rods 31 whose ends are joined to blocks 32 of concrete or other, preventing their displacement and consequently the tilting of the blocks 28 under the reaction force due to the traction created by the cables 20 and 26.

Depending on the case, the pairs of cables, respectively 20 and 26, provided along the sides and outside the frame 13 on the one hand, in the sole 14 of the frame on the other hand (Figures 2 and 3 in particular) can be anchored at their ends directed towards the excavation 25, or on the bosses 12 provided on the strike off 3 as far as the cables 20 are concerned, the cables 26 being joined to the supports 28, that is to say all of them together on these supports, the strike off being in this case free of bosses 12 as shown in FIG. 7.

It is also possible to anchor the cables 20 on the foundations 28 and the cables 26 on the bosses 12 or vice versa.

In all cases, the force exerted by the traction on the cables 20 (and 26), creates on the raft 3 a tensile force which tends to pivot the latter and in particular to tear it from the ground 7, notwithstanding its immobilization by the spades 6 provided at the front of the raft, in the direction of the excavation.

This is why and according to an improvement advantageously coming within the scope of the present invention, provision can be made, during the installation of the raft 3 in line with the excavation 25 and as shown in FIG. 8, an additional table 33, stretched at one end 34, against the front part 35 of the raft and, at its opposite end 36, in the vicinity of the lower part of the sheet 6 disposed in front of this raft, so as to exert a torque on the latter , balanced by the tensile force exerted on the cable 20 to ensure the displacement of the frame 13 on this raft.

Claims (16)

Method for the construction of a structure under a support slope of a railroad track (1) or a carriageway, consisting in temporarily cutting the track in line with the location provided in the support slope (2) of this track for the passage to be carried out, and to carry out an excavation (25) by excavating the ground in this location, characterized in that it consists in previously manufacturing or disposing, on at least one side of the excavation, if necessary in each on both sides thereof, on either side of the slope and opposite one another, at least one flat raft (3) for support and guide for a hollow frame (13 ) in concrete, the frame being carried by the raft outside the excavation, to put in place, parallel to the lateral sides of the hollow frame, at least one traction cable (20), this cable being secured at one end d '' a fixed anchor point (12, 28) while the other end is engaged with a jack (19) port é by the frame, so that the tensile force exerted on the cable by the jack is translated, as a result of the reaction on the anchoring boss, by a pushing effect on the frame which gradually slides on the raft then on the ground of the excavation (25), to ensure its direct penetration into it, in front of the raft. Method according to claim 1, characterized in that the flat base (3) is arranged so as to make it include a boss (12) constituting the anchoring point of the traction cable (20), this boss being disposed in the vicinity from the end of the raft directed towards the excavation (25). Method according to claim 3, characterized in that the anchoring point is constituted by means of a block (28), immobilized in the ground (7), disposed on the other side of the excavation (25) relative to the raft (3), the traction cable (20) extending through the excavation. Method according to any one of Claims 1 to 3, characterized in that it consists in associating each frame (13) with two first parallel cables (20), extending respectively along each of the lateral sides (15, 16) of this frame. Method according to any one of claims 1 to 4, characterized in that each frame (13) is made to cooperate with four parallel cables (20, 26), two by two symmetrical on either side of the median plane of the frame , the first two cables (20) being arranged along the lateral sides outside the frame, while the second two (26) pass freely through longitudinal passages provided inside the lower slab (14) of the frame. Method according to claim 5, characterized in that two anchoring points are provided, formed by bosses provided on the base on each side of the frame (13) for a pair of parallel cables (20), and two other points of anchoring formed by two solid masses (28) immobilized in the ground (7) for the other pair of cables (26). Method according to claim 6, characterized in that the cables of one of the pairs are the first cables (20) and the cables of the other pair are the second cables (26), or vice versa. Method according to any one of Claims 1 to 7, characterized in that the anchoring bosses (12) of the cables (20) are arranged in the front part of each slab (3), as close as possible to the sides of the excavation (25) in the slope (2), the traction cylinders (19) being mounted in the rear part of the frame (13) supported by the raft. Process according to any one of Claims 1 to 8, characterized in that each raft (3) is made to comprise a sole (6), of rectangular profile, the width of which is substantially equal to that of the frame (13). Process according to any one of Claims 1 to 9, characterized in that the raft (s) (3) is immobilized on the ground (7), on each side of the slope (2) supporting the track (1), by means of projecting parts (6), suitable for being buried in the ground so as to constitute "spades" for anchoring each raft. Method according to claim 10, characterized in that the raft (s) (3) are placed in compression by means of an additional cable (33), stretched between one of the projecting parts (6) in the vicinity of the end of the raft , directed towards the excavation (25) and the opposite end (35) of this raft, this cable exerting a prestressing force on the raft which is opposed to that created by the traction cables (20, 26). Method according to any one of Claims 1 to 11, characterized in that each lateral frame (13) made of concrete has external bosses (18) allowing the mounting of the traction cylinders, each of these external bosses being provided opposite a boss (12) or an anchor block (28). Method according to any one of Claims 1 to 12, characterized in that multi-wire cables formed from strands (21) are used, the ends of which are integral with a support plate (24) which abuts on the opposite face of the anchoring boss (12). A method according to any one of claims 1 to 13, characterized in that laterally housed on each raft (3) raised edges (11) for the lateral guidance of the frame (13) carried by this raft. Method according to any one of Claims 1 to 14, characterized in that a layer of bentonite or other similar material is injected between the lower face of each frame (13) and the upper face of the base (3). lubricate each other's facing surfaces to improve the sliding of the frame. Work constructed under a railroad track or the like, by implementing the method according to any one of claims 1 to 16.

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