EP0245155A1 - Process for carrying out works under railway tracks in operation - Google Patents

Abstract

1. A process of constructing civil engineering works under lines of rails which are being used, especially of constructing an underpass or a pedestrians'subway traversing a dam or like embankment which supports the rails, characterised in that the process comprises : forcing beneath the dam (1), in a manner known per se, two pairs of hollow half-abutments (3, 4) which are disposed in respective opposed pairs on either side of the subway to be constructed and which leave beneath the lines of rails a limited thickness of dam material (24) between said rails and the top of said abutments, causing two respective ones of said half-abutments to abut each other substantially in the central longitudinal plane of the dam (1), joining these half-abutments in their mutual abutting zones on either side of said central plane, mounting stiffeners (19, 20) beneath said lines of rails (2) along a length thereof which is somewhat greater than the distance between the two pairs of half-abutments, removing either before or after forcing of said half-abutments the dam material beneath the stiffeners between the lines of rails and the half-abutments to be joined, placing two supporting girders (22) on top of each pair of said two pairs of half-abutments, removing the stiffeners and subsequently cutting the lines of rails along a length corresponding to the width of the subway, removing the dam material remaining between said supporting girders to a thickness which is required for mounting two prefabricated semi-slabs (12, 13) which are inserted from each side or from only one side of the subway, said two semi-slabs being moved sideways onto the supporting girders or onto the top of said half-abutments so that they rest thereon with their ends abutting each other, reconstructing the lines of rails above said semislabs, and clearing the subway (25) between the two pairs of half-abutments beneath the lines of rails.

Description

The present invention relates to a method allowing the construction of works such as railway, motorway, road or pedestrian crossings through any embankment or earthworks supporting one or more railways, without requiring the prolonged stopping of traffic flowing on these tracks.

A process is already known which authorizes the construction of works of the kind of road crossings under railways the direction of which is generally transverse to that of this passage, which consists in using prefabricated elements delimiting the latter and put in place through the embankment or the like supporting the tracks after having provided therein a trench of appropriate dimensions. However, this solution has the major drawback of requiring the sectioning of the tracks over the length corresponding to the passage, then after earthwork of the slope to clear through it the adequate space, to make the prefabricated elements rip, before being able to finally, once these elements are assembled and the whole consolidated, reconstruct the tracks. With such a method, the stopping of traffic is necessarily prolonged, at least 48 hours under the best conditions and for a structure of relatively limited dimensions. Such an extended stop is particularly detrimental, especially if the railways concerned provide heavy traffic during normal periods.

Another solution consists in putting in place auxiliary aprons routed by wagons or other means of transport, resting on concrete or wooden camels. After earthworks under these auxiliary decks, the structure is built in successive sections, requiring a longitudinal displacement of the auxiliary decks. Again, this process, which requires very significant means of implementation, leads to prolonged immobilization of traffic, with the drawbacks which result from this, even if the work is carried out at night or during the weekend.

Finally, reference can be made, in the known state of the art, to a so-called jacking method, which consists in forcing a hollow structure constituting a hollow structure constituting the framing of the passage to be produced, this structure being pushed gradually into the ground, the earth of the embankment being gradually withdrawn from the interior of this structure. Force penetration of the latter is achieved by means of jacks which bear on one side of the structure and on a solid abutment fixed of sufficient dimensions to be able to offer a suitable reaction to the thrust of the jacks. In this case, however, it is obvious that the efforts to be developed are considerable, especially as soon as the structure to be put in place has significant dimensions, which leads to particularly high implementation costs. In addition, the method in question requires prior reinforcement of the tracks, which is also costly and time-consuming, again causing the need to slow down or even interrupt traffic for a relatively long period.

The present invention relates to a method which makes it possible to avoid the drawbacks of the solutions recalled above, by ensuring the realization under the embankment or more generally the support structure of railways or the like, of a road or pedestrian crossing without require a long-term interruption of traffic, which is easy to implement and which entails only reduced costs, whatever the transverse dimensions of the structure to be produced.

To this end, the process considered is characterized in that it consists of driving transversely in a manner known per se, under the slope, two pairs of half-abutments or straight hollowed feet, arranged two by two opposite one another and on the other side delimiting the passage to be produced and providing beneath the tracks, between them and the upper face of the half-abutments, a limited fill thickness, to bring the half-abutments two by two in abutment substantially in the plane longitudinal median of the slope, to wedge these half-abutments in their mutual junction zone on either side of this median plane, to be fitted in place under the stiffener tracks over a length of these slightly longer than that which separates the two pairs of half-abutments, before or after driving them, to remove the fill between the tracks and the abutments abutting under the stiffeners, to be placed on the two pairs of half-abutments respectively two support bases resting on these half-abutments, to remove the stiffeners and then cut the tracks over a length corresponding to the width of the passage, to level the embankment remaining between the box springs to a thickness necessary for the casing of two prefabricated half-decks placed on each side or d '' only one side of the passage, these half-aprons being ripped laterally on the box springs or on the top of the abutments, to make them rest joined at their ends, to reconstitute the tracks on the half-aprons and to complete the earthwork of the passage between the two pairs of half-abutments under the tracks.

According to a particular characteristic of the method of the invention, the driving of the two half-abutments of each pair is carried out using cables crossing the slope, each fixed at one end to a half-abutment and secured to the other end of a jack bearing on the other half-abutment and exerting on the cable a tensile force ensuring the mutual approach of the half-abutments.

Advantageously and according to another characteristic also, the two half-decks are produced by pouring concrete on either side of the slope on scaffolding extending parallel to the tracks and surmounting the two half-abutments of the two pairs, arranged on each sides of the slope. Preferably, the casting and drying of the half aprons are made during the sinking operations of the half-abutments in the slope.

The method according to the invention thus allows an optimal organization of the successive operations to be carried out, among which the cutting of the tracks and the interruption of the traffic which results therefrom are reduced to the minimum, corresponding to the only installation of the half-decks, them - Same previously constructed to the dimensions exactly provided on either side of the slope during the prior operations of sinking the half-abutments, strengthening the tracks and making the box springs intended to receive these decks.

In particular, the method of the invention makes it possible, without having to cut the tracks, to produce under them, in the limited space available between the upper face of the half-abutments once joined and the tracks themselves, the box springs support for aprons.

Depending on the case, the box springs are poured in place or the prefabricated box springs are sealed on the half-abutments so as to make up for any misalignment of the contiguous faces of the half-abutments. Alternatively, the half-decks are previously built on the two box springs which are ripped with the decks on the half-abutments under the tracks.

The invention consequently provides both a very great economy in the handling and manufacturing means necessary for the implementation of various stages of the envisaged process, and also a speed in the accomplishment of these stages, by therefore authorizing a particularly significant reduction in the total cost of these operations. It should be emphasized that all these stages enter into the final construction of the structure, which is an additional factor of economy, compared to all the other methods which introduce additional stages which affect the overall cost of the structure. In addition, it should be emphasized that the nature and the sequence of these operations are in no way dependent on the transverse and even longitudinal dimensions of the passage to be carried out. under the tracks, perpendicular to them, the process could just as well be applied for works requiring several successive spans, based on as many pairs of parallel transverse half-abutments, the decks supported by these half-abutments two by two being able to have longitudinal dimensions as large as necessary.

• - La figure 1 est une vue en coupe transversale d'un talus supportant des voies de chemin de fer sous lesquelles est à réaliser, selon l'invention, un passage routier ou piétonnier, illustrant la mise en place préliminaire de deux demi-culées.
• - La figure 2 est une vue analogue à la figure 1, expliquant le processus de fonçage des deux demi-culées.
• - Les figures 3 et 4 sont à nouveau des vues analogues aux précédentes mais destinées à expliciter diverses étapes ultérieures de la mise en oeuvre du procédé.
• - La figure 5 illustre en deux demi-coupes longitudinales selon la direction des voies ferrées, respectivement à gauche sur le dessin de la réalisation des sommiers de support des tabliers, et à droite le montage de ces derniers sur ces sommiers.
• - La figure 5a illustre une variante de réalisation des sommiers et des tabliers.
• - La figure 6 est une vue en perspective partielle des moyens de renforcement fixés sous les voies.
• - La figure 7 est une vue en perspective permettant de préciser l'ensemble des opérations réalisées selon l'invention.
• - Les figures 8 et 9 illustrent une variante de mise en oeuvre du procédé selon l'invention au moyen de paires de demi-culées perfectionnées.
• - La figure 10 enfin, représente à plus grande échelle l'avant-bec d'une des demi-culées, muni d'un perfectionnement facilitant son déplacement dans le talus à travers lequel s'effectue le fonçage de cette demi-culée.

The invention will be more clearly explained through the following description of an example of implementation of the process under consideration, given by way of non-limiting example, with reference to the appended drawings in which:

• - Figure 1 is a cross-sectional view of an embankment supporting railway tracks under which is to be produced, according to the invention, a road or pedestrian crossing, illustrating the preliminary establishment of two half-abutments.
• - Figure 2 is a view similar to Figure 1, explaining the sinking process of the two half-abutments.
• - Figures 3 and 4 are again views similar to the previous but intended to explain various subsequent stages of the implementation of the method.
• - Figure 5 illustrates in two longitudinal half-sections in the direction of the railways, respectively on the left in the drawing of the production of the support bases of the aprons, and on the right the mounting of the latter on these bases.
• - Figure 5a illustrates an alternative embodiment of the bed bases and aprons.
• - Figure 6 is a partial perspective view of the reinforcing means fixed under the tracks.
• - Figure 7 is a perspective view to specify all of the operations performed according to the invention.
• - Figures 8 and 9 illustrate an alternative implementation of the method according to the invention by means of pairs of improved half-abutments.
• - Figure 10 finally, shows on a larger scale the front spout of one of the half-abutments, provided with an improvement facilitating its movement in the slope through which the sinking of this half-abutment takes place.

In FIGS. 1 to 7, an embankment for supporting one or more railway tracks has been designated under the reference 1. Of course, it goes without saying that the particular shape of this embankment, as well as the nature or the arrangement tracks 2 have no direct impact on the implementation of the method according to the invention, which can be applied identically to make a passage under any earthwork supporting different tracks, even if its application to railways seems particularly advantageous.

In order to provide a free passage under these routes, for example for road and / or pedestrian use, pairs of hollow half-abutments or straight feet 3 and 4 respectively are used, arranged on either side of the slope 1, these half -cuts with a hollow structure 5 (Figure 5) allowing in particular, once the work is completed and as we will see later, pedestrian traffic for example, the space between the abutments of two neighboring pairs being reserved for vehicles . In particular, it should be considered here that the method according to the invention, described below in relation to an example using two pairs of half-abutments of the preceding type, could be adapted with a larger number of such pairs, by particularly if the width of the passage to be made is very large, the pairs of half-abutments then constituting two by two of the neighboring spans.

The half-abutments 3 and 4 in each pair are joined in pairs through the slope 1 by means of prestressing cables 6, each fixed at one end 7 to one of the half-abutments 3 and to the other on a hydraulic or other cylinder 8, carried by the facing half-abutment. The number of cables 6 thus connecting the two half-abutments is chosen according to the efforts to be developed to ensure the sinking of one towards the other through the ground of the slope 1 so as to bring these elements together and gradually one the other. The soil 9 which progressively fills the internal hollowed out part 5 of the half-abutments during their respective advances is continuously evacuated by an excavator belt 10 or by any other suitable earthmoving means. It will be noted in this regard that this technique of mutual sinking of hollow structures towards each other is now known in the art but results from work and publications of the applicant.

Parallel to the installation of the half-abutments 3 and 4 on each side of the slope 1, there are above them, parallel to the tracks 2 and on the abutments belonging to two adjacent pairs, scaffolding 11 which thus overcome two half-abutments 3 or 4 depending on the side where they are provided, these scaffolding being intended to support respectively two half-decks 12 and 13, which will be adapted to constitute, once the work is completed, the deck or the support cross-member of track 2 above the transverse passage to be made under the slope 1. These half-decks 12 and 13 can be made in any manner known in the building technique, in particular be cast in formwork on site at the exact dimensions of the span to be obtained between the abutments which will form the lateral sides of the passage. It should be noted that, depending on the case, the two half-decks can be manufactured either on the same side or on either side of the slope.

The shape and structure of these half-aprons is again without direct impact on the implementation of the method. In particular, they can be partially or totally prefabricated and brought directly by suitable handling equipment to their scaffolding, or else be built directly on these, in taking advantage of the time necessary for the sinking of the abutments for their manufacture and in particular if they are made of poured concrete for sufficient drying thereof.

When the two half-abutments 3 and 4 in each pair are sufficiently driven into the slope 1, in particular when their end point 14 comes into junction from one to the other substantially in the median longitudinal plane of the slope 1, we continues the removal of the earth until the continuity of the conduit materialized by these abutments is thus achieved face to face. At this instant, they are claved together in their inclined pan regions 15 provided between them or merlons, the point shape of each half-abutment being generally adopted to avoid a landslide during sinking. During this keying operation, this is ensured by placing and sealing concrete sheets of suitable profile or more simply by filling the space thus delimited by a layer of concrete poured into a formwork or projected, in continuity with the walls of the abutments themselves, the extension of one and the other of these which then delimit through the slope and two by two a continuous corridor open at its two ends, the upper face 16 of the half abutments which are arranged in a horizontal plane if the sinking has been carried out under optimal conditions but which may, if necessary, have a slight offset in height from one to the other, which, as will be seen, has no drawbacks but only requires a backlash by an appropriate concrete connection.

In the following phase, we then reinforce the tracks 2 on a longitudinal dimension of these a little greater than that which separates the pairs of half-abutments previously abutted as said above. As a variant, the stiffening can be carried out before the half-abutments are driven. This reinforcement is advantageously carried out as shown in FIG. 6 by arranging on the wooden crosspieces 17 carrying the rails 18 of the tracks 2 of the longitudinal irons in H or in 1 19, fixed on these crosspieces and under which are welded or bolted transversely of other irons 20, giving the assembly a suitable stiffening power. Naturally, it It is clear that the structure of these irons and more generally the manner in which the strengthening of the tracks 2 is carried out has no direct impact on the invention, the only imperative being to be able to stiffen them sufficiently to allow, without creating unacceptable deflection, to evacuate under the tracks to the right of the abutments 3 and 4 parallel to the upper surface 16 thereof, holding the fill to leave free a space 21 of limited height.

It should be noted that during this operation, as indeed during all of the above, the rail traffic had at no time to be stopped, the strengthening of the tracks being able to be easily carried out between two successive train passages. In addition, the excavation of the space 21 is limited to sufficient dimensions for this reinforcement to be able to provide the necessary rigidity without having to interrupt the traffic.

Once the space 21 has been made free, there is on the surface 16 of each pair of half-abutments a box spring 22 transverse to the tracks, if necessary having a lateral reinforcement 23 preventing the earth cuttings from coming to fall on the box spring itself. This box spring 22 can be produced by means of a prefabricated element riped on site or manufactured in situ with adequate dimensions corresponding to the width of the two half-decks 12 and 13. Possibly, and as already said, the installation of the bed base 22 can be carried out with a backlash at the junction of the two corresponding half-abutments 3 and 4.

In the next step, the tracks 2 are then sectioned between the box springs 22 thus produced on the half-abutments of the two adjacent pairs delimiting the width of the passage to be carried out, then the fill 24 is removed above the plane 16 of the abutments in order to allow, by any suitable conventional means, - to make the half-aprons 12 and 13 slide towards each other by bringing them, at the end of the race, to rest on the box springs 22 whose spacing has been exactly determined beforehand (FIGS. 3 and 4). As a variant, and as schematically illustrated in FIG. 5a, the box springs 22 and the aprons 12 and / or 13 can be made both outside the track and then, once these aprons resting on the box springs, ripped together under tracks 2 on the corresponding half-abutments.

The half-decks 12 and 13 being thus in place and contiguous under the location of the tracks, these can then be immediately reconstituted, the implementation of the process having therefore interrupted the actual traffic on them only for one very short period of time, a few hours at most, just essential for cutting the tracks and removing them from earthwork, shifting the decks and restoring the continuity of the rails, ballast and other ordinary accessories constituting the tracks.

With the rail traffic resumed, the finishing of the structure can then be undertaken without interfering with the traffic, consisting on the one hand of laying out the edges of slope 1 at right and beyond the outcrop of the half-abutments and terracing the floor under the half-decks to clear the space 25 constituting the passage thus made under the tracks (Figure 5).

A work of art is thus produced, in particular a passage under rolling tracks, under conditions which, while providing security for the subsequent flow of traffic on these tracks, allow a saving of time and an economy of means particularly appreciable. The invention can naturally be adapted to particular geometries of works and / or railways, without modifying the general principles of its implementation which in all cases lead to a quite significant reduction in the time when the tracks are unavailable, all operations before and after this single step in the process being carried out without interrupting traffic.

Consequently, it should be considered that the invention is not limited to the single example of implementation more especially described and represented; it embraces all its variants. Thus, and as illustrated in FIGS. 8 and 9, it is advantageous to implement, in particular when the configuration of the slope requires it, the use of half-abutments of great height, structures which, while remaining in one piece, are divided into several staggered parts, for example 3a and 3b for the half-abutment 3 and 4a and 4b for the half-abutment 4. Each of these parts thus has a front spout or point 26 , the two front spouts of each abutment being located in the same vertical plane 27. The average inclination of the front spouts 26 is here chosen equal to 45 ^* , which makes it possible to keep a slope of 3/2 during the earthwork of the cutting face during sinking of the half-abutments in the manner specified above. This results in a significant reduction in the depth theoretically necessary in the case of a single slope forearm, in order to ensure the stability of the slope 1 during this driving.

Once the two half-abutments 3 and 4 have been docked (FIG. 9), the keying thereof as and when the earthworks in the central part or merlons 15 are carried out by shielding the side walls of the half -culated. These earthmoving and shielding operations are carried out from top to bottom, the particular shape of the front spouts 26 of these half-abutments making it possible to significantly reduce the length and the surface of this shielding.

It should be noted that the production of stepped half-abutments in accordance with the above characteristics provides two other advantages. Firstly, each half-abutment comprises at the level of the separation of its successive stages 3a, 3b or 4a, 4b, an intermediate slab 28, suitable for serving as a strut when the half-abutments are approached and keyed together, allowing reduce the amount of steel required to hold the right feet. Secondly, thanks to the splitting of the half-abutments with serrated front-beaks 26, it can be seen that only the lower tooth 26 penetrates, at the start of the sinking operation in the slope 1. The backfill load at - Above this front spout is therefore relatively limited, which entails a risk of lifting when the force necessary for driving is exerted. With the proposed solution, the upper front spout 26 provides by itself a permanent overload on the lower stage directed downwards, which avoids the risk of lifting when advancing the corresponding half-abutment.

Another improvement usefully envisaged, whatever the method of carrying out the method of the invention according to the variants envisaged above, consists in arranging the front-nozzles 26 of the half-abutments 3 and 4 so as to facilitate the advance of these in the thickness of the slope 1, during the sinking operation of these half-abutments.

For this purpose, the front spout is constituted, as illustrated in FIG. 10, by means of a T-section 29, on which is welded at one of its ends a flat iron 30, slightly sloping with respect to the profiled, so as to compact the ground over a limited thickness, for example of the order of 2 cm. In the space thus cleared behind the front spout, can then be injected a liquid mud 31, of the thixotropic mud kind or other liquid, of the kind of a gel for example, which ensures a certain lubrication of the walls of the half abutment, during its advance. This mud is advantageously brought into place by a tube 32, embedded in the concrete 33 of the half-abutment, between the reinforcing bars 34, and connected at its opposite end (not shown) to a low pressure pump.

Claims (12)

1- Method for the construction of engineering structures under railway tracks in operation, and in particular of a road or pedestrian crossing through an embankment or similar earthwork supporting the tracks, characterized in that it consists of running transversely from in a manner known in itself, under the embankment (1), two pairs of half-abutments (3, 4) or hollowed-out straight feet, arranged in pairs opposite each other on the sides delimiting the passage to be made and providing under the tracks, between them and the upper face of the half-abutments, a limited fill thickness (24), to bring the half-abutments two by two in abutment substantially in the median longitudinal plane of the slope (1), to wedge these half-abutments in their mutual junction zone on either side of this median plane, to mount in place under the tracks (2) of the stiffeners (19, 20) over a length of these slightly greater than that which separates the two pairs of half-abutments, before or after sinking of these half-cu lées, to withdraw the fill between the tracks and the abutments abutting under the stiffeners, to have on the two pairs of half-abutments respectively two support bases (22) resting on these half-abutments, to remove the stiffeners and then to cut the tracks over a length corresponding to the width of the passage, to level the embankment remaining between the box springs to a thickness necessary to enclose two prefabricated half-decks (12, 13) placed on each side or on one side only of the passage, these two half-aprons being ripped laterally on the box springs or on the top of the half-abutments, to make them rest joined by their ends, to reconstitute the tracks on the half-aprons and to complete the earthwork of the passage (25) between the two pairs of half-abutments under the tracks. 2- Method according to claim 1, characterized in that the driving of the two half-abutments (3, 4) of each pair is carried out using cables (6) crossing the slope, each fixed at one end (7) to one half-abutment and secured to the other end of a jack (8) bearing on the other half-abutment and exerting on the cable a tensile force ensuring the mutual bringing together of the two half-abutments. 3- A method according to claim 1, characterized in that one realizes by pouring concrete the two half-decks (12, 13) on either side of the slope (1) on scaffolding (11) extending parallel to the tracks (2) and surmounting the two half-abutments (3, 4) of the two pairs arranged on each side of the slope. 4- Method according to claim 3, characterized in that the casting and drying of the half-decks (12, 13) are carried out during the sinking operations of the half-abutments (3, 4) in the slope (1). 5- Method according to claim 1, characterized in that the box springs (22) are poured in place or one proceeds to the sealing on the half-abutments (3, 4) of prefabricated bed bases, so as to make up for a possible defect in alignment of the contiguous faces of the half-abutments. 1 6- A method according to claim 1, characterized in that the two half-aprons (12, 13) are previously mounted on the two bases (22) which are ripped with the two aprons on the half-abutments under the tracks. 7- Device for implementing the method according to any one of claims 1 to 5, characterized in that it comprises a self-driving assembly of hollow half-abutments two by two opposite share and other of the slope, means for manufacturing two longitudinal half-decks extending laterally between and above two half-abutments of two adjacent pairs, means for producing and placing transverse bed bases receiving the half-decks and each extending over two half-abutments of the same pair and members for temporarily stiffening the tracks to support them during the production of the box springs. 8- Device according to claim 7, characterized in that the half-abutments (3, 4) made in one piece, are divided into several stepped parts (3a, 3b, 4a, 4b). 9- Device according to claim 8, characterized in that the half-abutments (3, 4) have at each level, front spouts (26) located in the same vertical plane. 10- Device according to one of claims 8 or 9 characterized in that, in each half-abutment (3, 4) the stages are separated by intermediate slabs (28) forming a strut. 11- Device according to any one of claims 7 to 10 characterized in that each half-abutment (3, 4) has in its front spout (26) a T-profile (29) on which is welded a flat iron ( 30) disposed on a slope on this profile, delimiting behind the front spout a space into which is injected a liquid mud (31). 12- Device according to claim 11, characterized in that the liquid slurry supply is effected by a tube (32) embedded in the concrete (33) of the half-abutment and connected to a low pressure pump.

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