EP1279770A2 - Railway support system for rails - Google Patents

Abstract

The supporting system consists of a base slab (15) laid on a bed (17) of stabilised sand, sleepers (13) for the rails (11), and anti-vibration soles (12) between the rails and sleepers. There are road surface slabs or beams (21) extending along the outsides of the rails, and slabs (22) between them, with the gaps filled by spacers (25) with static and dynamic rigidity selected to be less than the sole plate. The spacers can be made with portions that pass beneath the rails, and the system can incorporate an anti-vibration layer between the base slab and sand bed.

Description

The present invention relates to the installation of railways on roads and in particular the installation of railways for trams.

• a) Au niveau de la stabilité de la voie, les voies ballastées classiques posent un problème en voirie du fait de leur tassement dans le temps et de la destruction de la voirie dans la zone des voies ;
• b) Au niveau de l'environnement, l'impact des vibrations et des bruits par suite du tassement de la voirie et de l'augmentation de la raideur dynamique du ballast provoque des transmissions vibratoires vers les fondations des immeubles avoisinants ;
• c) Au niveau de la maintenance de la voie, les tassements localisés du ballast provoque une déflexion locale importante de la voie, ce qui entraîne une usure plus importante de l'infrastructure et du matériel roulant ;
• d) Au niveau de la mise en oeuvre de la voie ferrée et du temps d'exécution et d'accès pour assurer la maintenance.

The installation of railways for street trams poses a problem which is located at different levels:

• a) In terms of track stability, conventional ballasted tracks pose a problem on the roads due to their settlement over time and the destruction of the roads in the track area;
• b) In terms of the environment, the impact of vibrations and noises as a result of the compaction of the roads and the increase in the dynamic stiffness of the ballast causes vibration transmissions to the foundations of neighboring buildings;
• c) In terms of track maintenance, localized settling of the ballast causes significant local deflection of the track, which leads to greater wear of the infrastructure and rolling stock;
• d) At the level of the implementation of the railway and the execution and access time to ensure maintenance.

The problem of track stability is solved by installing the track on a concrete slab slab. Such a railroad installation is described in publication WO 98/51863. In this known installation, however, no measure is planned to reduce the transmission of the acoustic and vibratory waves generated by the passage of vehicles on the railway towards the foundations of neighboring buildings.

The invention relates in particular to the problem of acoustic and anti-vibration insulation of railways installed on roads. In order to solve this problem in a global manner, the inventors set out to analyze the static behavior and the dynamic behavior of the railway track when a vehicle passes over the rails. A car traveling on the rails produces two impacts on the rails. The first is due to the mass of all the cars in the train: it is the static load transferred to the bogies; the second impact is due to the mass not suspended from the bogie: it is this mass which produces the dynamic impulses by the wheels on the rails and it is these impulses which are transmitted towards the environment.

• a) Une composante vibratoire constituée des ondes de chocs émises par le passage de la rame et propagées par le sol: la propagation de ces vibrations est fonction des caractéristiques intrinsèques du sol ;
• b) Des bruits solidiens résultant des vibrations des constructions produites par les ondes vibratoires transmises par le sol ;
• c) Des bruits aériens résultant de phénomènes ondulatoires transmis directement par l'air.

Overall, the acoustic and vibration phenomena that arise when a train passes over the rail supports include several components, among which we can cite:

• a) A vibratory component consisting of shock waves emitted by the passage of the train and propagated by the ground: the propagation of these vibrations is a function of the intrinsic characteristics of the ground;
• b) Solid noises resulting from the vibrations of constructions produced by the vibratory waves transmitted by the ground;
• c) Airborne noise resulting from wave phenomena transmitted directly by the air.

The transmission of acoustic and vibration waves generated during the passage of a tram on a railroad track is illustrated in Figure 1. The vibration waves A are propagated by the ground and are generated by the impact of the wheels of the cars of the tram on rails. Solidiens noises B result from the vibrations of neighboring constructions receiving the vibratory waves A transmitted by the ground. C waves are air noises resulting from wave phenomena transmitted directly by the air. The rail support system according to the invention aims to reduce to a minimum the transmission of these wave phenomena.

The first flexural resonance frequency of the wheel / rail assembly is conditioned by the dynamic stiffness of the soles placed under the rails and, if necessary, by that of the cushions placed under the saddles or crosspieces. This resonant frequency is inversely proportional to the anti-vibration performance of the rail fastening system. A low resonant frequency provides better vibration isolation than a high resonant frequency. However, there is a lower physical limit below which the dynamic stiffness of the soles used cannot go down because the dynamic stiffness of the soles is directly related to their static stiffness and the static stiffness of the soles cannot be too low because it influences the rail deflection directly when a vehicle passes over the rails. Insulation performance Better antivibration is obtained by decoupling the fixing function and the insulation function.

To solve the problem of acoustic and anti-vibration insulation which arises during the operation of a railway track on roads, it is therefore necessary to provide an appropriate anti-vibration support system, which is adapted to the characteristics of the ground and to the transmissibility acoustic and vibratory waves to the environment. In order to develop such a support system so as to optimize the performance of sound insulation and antivibration, the inventors have devised a method and a device for analyzing the static behavior and the dynamic behavior of a railway track and determining the frequency specific to the track system, deflections to the right of the supports and damping of rail vibrations. These analyzes have led the inventors to determine the features to be incorporated into the rail support system in order to optimize the acoustic and anti-vibration insulation and reduce the transmission of vibratory waves to the environment.

The invention thus provides a railroad support system in which the rails of the track are fixed to a slab slab of prefabricated reinforced concrete or poured on site, placed on a bed of stabilized sand placed on the bottom of the trunk of the site and, on each outer side of the track, is placed a prefabricated road slab or beam sealed at a lateral edge of the slab slab. Between the rails of the track is placed a prefabricated reinforced concrete road slab. With the aim of separating the rails from the road network and not neutralizing the dynamic behavior of the rails, each rail is separated from the concrete road slabs by separation elements which isolate the rail from the neighboring slab. These separating elements, consisting of prefabricated elements or of a waterproof and flexible filling product, are chosen so that the static and dynamic stiffnesses of the assembly are less than those of the flanges placed under the pads of the rails. The rails are thus completely independent of the roads, which has the consequence of considerably reducing the transmission of vibrations to the foundations of neighboring buildings at the same time as sealing is ensured along the rails.

A system in which the rail is coated with a very compact resilient material to give it better mechanical resistance to expansion and to the forces generated by the movement of cars on the rail does not have the static and dynamic characteristics required to ensure effective vibration isolation and, therefore, the transmission of vibration waves to the foundations of neighboring buildings is maximum.

In the railroad support system according to the invention, the rails can be fixed to the slab slab in different ways: by means of saddles or crosspieces or even by direct laying on the slab slab. Under the pad of each rail is usually interposed a rigid or anti-vibration sole. Often below and underneath each saddle or cross member is an anti-vibration pad.

The anti-vibration soles are chosen with static and dynamic stiffnesses such that the first resonance frequency of the wheel-rail-support system is located below approximately 60 Hz. This provides a more effective anti-vibration filter to dampen the vibration waves to the environment. For comparison, the first resonance frequency of a conventional ballasted track (wheel-rail-ballast system) can vary from 60 to 110 Hz. A high-performance antivibration isolation is obtained with anti-vibration devices made so that the rigidity static is less than 2x10 ⁷ N / m and that the dynamic rigidity is less than 4x10 ⁷ N / m.

To limit the deflection of the rail during the passage of the wheels to a tolerable value of 1 to 2 mm, it is necessary to choose for the soles or the anti-vibration supports static and dynamic stiffnesses such that the successive supports along each rail are alternately a support relatively rigid and relatively flexible support.

• a) une fréquence de résonance plus basse qu'avec un système à raideur uniforme ;
• b) un amortissement amélioré des ondes de chocs ;
• c) une réduction des vibrations transmises dans le sol ;
• d) une limitation de la déflexion statique des rails lors du passage des roues ;
• e) une flexion des rails plus courte, ce qui entraîne une réduction du rayonnement acoustique ;
• f) l'absence de superposition des vibrations dues aux deux roues d'un bogie.

This alternation of stiffness along the track has the advantageous consequences:

• a) a lower resonant frequency than with a uniform stiffness system;
• b) improved damping of shock waves;
• c) a reduction in vibrations transmitted to the ground;
• d) a limitation of the static deflection of the rails during the passage of the wheels;
• e) shorter bending of the rails, which results in a reduction of the acoustic radiation;
• f) the absence of superposition of vibrations due to the two wheels of a bogie.

On the other hand, to further reduce the first resonant frequency and further improve the antivibration insulation performance, the rail fastening devices advantageously include adjustable fastening means applying an adjustable prestressing force to the anti-vibration soles. Prestressing means can also be provided in the case of direct laying of the rails on the slab slab in order to apply a prestressing force to the web of the rails.

In a railway track support system, the acoustic and anti-vibration insulation performances are linked to an optimal combination of the characteristics of the elements involved in the production of anti-vibration devices. In order to develop the correct support system for the railway, it is therefore essential to be able to check and correctly measure both the static and dynamic behavior of the wheel / rail / support assemblies of a railway. This requires both an appropriate railway test device and an appropriate test procedure.

An additional aspect of the invention therefore relates to a test bench for verifying the static and dynamic behavior of a railroad track and a method of implementing this test bench in order to allow the optimal development of the supports. anti-vibration of a railroad track in order to optimize its acoustic insulation and anti-vibration performance.

• La figure 1 illustre la transmission des ondes acoustiques et vibratoires à partir d'une voie ferrée de tramway vers les immeubles avoisinants ;
• La figure 2 est une vue en coupe transversale d'un tronçon de voie ferrée en voirie, installé avec une forme de réalisation du système de support de rails suivant l'invention ;
• La figure 3 représente, à échelle agrandie, une variante d'exécution d'un détail de la figure 2 ;
• La figure 4 est une vue en coupe semblable à celle de la figure 2, mais illustrant une deuxième forme de réalisation du système de support de rails suivant l'invention ;
• La figure 5 illustre une troisième forme de réalisation du système de support de rails suivant l'invention ;
• La figure 6 illustre un exemple de dispositif de fixation de rail ;
• La figure 7 illustre une quatrième forme de réalisation du système de support de rails suivant l'invention ;
• La figure 8 illustre un dispositif de mise en précontrainte d'un rail dans le système de support suivant l'invention ;
• La figure 9 représente schématiquement un banc d'essai permettant d'analyser le comportement statique et dynamique d'une voie ferrée en tenant compte des charges par essieu et de la masse non suspendue du bogie.

Other features and advantages of the invention will appear on reading the description of a few examples of embodiments illustrated in the attached drawings.

• Figure 1 illustrates the transmission of acoustic and vibration waves from a tramway track to neighboring buildings;
• Figure 2 is a cross-sectional view of a section of railroad track, installed with an embodiment of the rail support system according to the invention;
• Figure 3 shows, on an enlarged scale, an alternative embodiment of a detail of Figure 2;
• Figure 4 is a sectional view similar to that of Figure 2, but illustrating a second embodiment of the rail support system according to the invention;
• FIG. 5 illustrates a third embodiment of the rail support system according to the invention;
• FIG. 6 illustrates an example of a rail fixing device;
• FIG. 7 illustrates a fourth embodiment of the rail support system according to the invention;
• FIG. 8 illustrates a device for prestressing a rail in the support system according to the invention;
• FIG. 9 schematically represents a test bench making it possible to analyze the static and dynamic behavior of a railroad track by taking account of the axle loads and the unsprung mass of the bogie.

In the drawings, the same reference designates an identical element or a similar or equivalent element. The embodiments illustrated in these drawings are given by way of nonlimiting examples. Variants of execution are possible according to the particular desiderata in each case.

Referring to Figure 2, there are shown two rails 11 of a tram track laid in accordance with the invention. In this exemplary embodiment, each of the rails 11 is fixed to crosspieces 13 with the interposition of a sole 12 which may be rigid or made of an anti-vibration material as a function of the loads provided per axle. The sleepers 13 of the two rails are anchored in a slab slab 15 of reinforced concrete, prefabricated or poured on site.

To this end, the slab slab has bowls to receive the lower part of the sleepers. The slab slab 15 rests on a layer of stabilized sand 17 placed on the bottom of the trunk (ground) 19. On the layer of stabilized sand 17 is preferably laid a draining layer 16 intended to drain water infiltration towards draining pipes 18 arranged at intervals along the track with a diameter and a spacing which are a function of the geographical location of the road. The slab slab ensures the stability of the installation. Optionally, a layer of anti-vibration material can also be placed between the stabilized sand bed and the slab slab.

Along the outer sides of the rails 11 extend slabs or road beams 21 which partially rest on the crosspieces 13 of the two rails and are sealed to the lateral edges 23 of the slab slab 15. Between the rails 11 are slabs of prefabricated roads 22 which rest on supports of level 24 adjustment consisting of very rigid resilient supports or anti-vibration supports defined according to the environment and the traffic planned on the road. A longitudinal closing flange 26 of poured concrete is inserted under the lateral edges of the slabs 22.

The spaces between the rails 11 and the road slabs 21 and 22 are filled with prefabricated separating elements 25 or made up of a waterproof and flexible filling product, the static and dynamic rigidities of which are chosen according to the anti-vibration soleplate under the rail.

More specifically, the static and dynamic stiffnesses of the separating elements 25 are chosen so that the static and dynamic stiffnesses of the entire support are less than those of the flanges placed under the rails. The rails are thus completely independent of the roads, which has the consequence of considerably reducing the transmission of vibrations to the foundations of neighboring buildings at the same time as sealing is ensured along the rails.

The vacuum between the road slab 22 and the slab slab 15 is preferably filled by injection of a suitable filling product 28 chosen according to the degree of insulation required by the environment.

FIG. 3 shows, on an enlarged scale, an alternative embodiment for the separation elements 25 which separate the rails from the road slabs. In this embodiment, the two separation elements surround the shoe of a rail 11, each element having a lower part 251 which extends under at least one part of the shoe. The lower parts of the two elements 25 are contiguous along faces 252 which extend in an oblique plane relative to the base of the shoe of the rail 11. In this way, the laitance which occurs during the pouring of concrete during the installation of road slabs 22 between the rails of the track cannot infiltrate and go back up into the gap between the cooperating faces 252, which avoids the formation of a concrete bridge which would transmit the vibrations of the rail to the foundations like this happens when the end faces of the bottom are vertical. In addition, the perfect junction between the lower parts of the separation elements under the rail pad stabilizes the seat of the rail.

In an advantageous embodiment, the successive supports along the track are made so as to alternately constitute a support relatively rigid and relatively flexible support. The advantages of this embodiment have been explained above.

As indicated above, the rails can be fixed in different ways depending on the size or the technique desired in the envisaged application or according to the degree of environmental protection that the owner wants to ensure.

FIG. 4 illustrates a case where the rail 11 is fixed to saddles 33 sealed in the slab slab 15, using an epoxy mortar, for example. On each saddle, the rail rests on a rigid or anti-vibration sole 12. The reference 31 designates a device for fixing a rail with joint bars. On the stabilized sand 17 are arranged, for example, a draining layer 35 and an anti-vibration isolation mat 37. According to the invention, the spaces between each rail 11 and the road slabs 21 and 22 are filled with separation elements 25 made of material having predetermined static and dynamic rigidities.

FIG. 5 illustrates a case where the rail 11 is also fixed to saddles 43 but where these are found fixed to the slab slab 15 by means of bolts. The road slab 22 here rests on leveling supports 24 which may be rigid or be made of an anti-vibration material. Note that an anti-vibration cushion can be interposed between each saddle and the slab slab. The void between the road slab and the slab slab can if necessary be filled by injecting an appropriate filling product.

FIG. 6 shows in particular an example of attachment 47 for fixing the shoe of a rail 11 on a saddle 43 with a protective cap 48 for attachment. The shoe of the rail rests on an anti-vibration sole 12.

FIG. 7 illustrates the fixing of a rail 11 on a saddle 43 which is itself fixed to the slab slab 15 by means of an adjustable fixing device 41 applying an adjustable preload to the anti-vibration sole 42 disposed under the saddle 43 This fixing device provides antivibration isolation at low resonance frequency. The fixing device illustrated comprises a prestressing spring 45 held between two abutment washers around a threaded rod 44. The spring 45 is compressed by the clamping nut 46 which adjusts the prestressing force. The fixing device may also include two springs having rigidities different and held between two washers around the threaded rod 44, the springs being compressed by the clamping nut 46 which adjusts the prestressing force.

FIG. 8 illustrates an arrangement locally maintaining the core of the rail 11 and applying to it an adjustable preload which gives the track a static and dynamic behavior ensuring perfect isolation of vibrations. The prestressing arrangement comprises a threaded rod 51 crossing the web of the rail 11 and extending between two resilient stops 53 applied against the lateral faces of a groove 14 formed in the slab slab 15. Springs 52 are arranged around the ends of the rod 51 and are adjusted in an adjustable manner against the resilient stops 53 by nuts 54. The core of the rail is held between two nuts 56 wedged on the rod 51. The adjustment of the nuts 54 and 56 adjusts the preload applied to the rail. After adjusting the nuts, the groove 14 is filled with a filling material, the characteristics of which are determined as a function of the stiffness of the anti-vibration sole 12 on which the rail 11 rests and as a function of the preload applied to the rail. The characteristics of the springs 52 are chosen as a function of the axle loads and the width of the groove 14. According to the invention, the spaces between each rail 11 and the road slabs 21 and 22 are filled with separation elements 25 in matter having predetermined static and dynamic rigidities.

In a railway track mounted on supports provided with anti-vibration elements, in particular when the anti-vibration elements are arranged at different levels, the acoustic and anti-vibration insulation performances are linked to an optimal combination of the characteristics of the elements involved in the production of the devices vibration. In order to develop the appropriate support system according to the real operating conditions, that is to say the characteristics of the soil from the point of view of the transmissibility of the vibratory waves to the environment, and according to the level insulation performance, it is essential to be able to measure and correctly analyze both the static and dynamic behavior of the wheel / rail / support assemblies of a railroad track.

To this end, the inventors have devised a measurement method by which the effects of the total static load applied to an axle of a vehicle having to travel on a railway track are decoupled from the equivalent of the unsprung mass of a bogie. The implementation of this method can be carried out, for example, using a test bench as shown diagrammatically in FIG. 9.

Figure 9 schematically shows a longitudinal view of an exemplary embodiment. The test bench comprises a frame on which are mounted at regular spacing springs with low resonance frequency 62. On these springs are fixed anti-vibration supports 61 used to carry a section of rail track to be tested. A mobile carriage 63 is mounted on wheels whose spacing is adjustable as a function of the spacing of the bogie axles of a vehicle. The mass of the carriage 63 simulates the unsprung mass fixed to the axle of a vehicle which is to travel on the railway. On the carriage 63 is mounted a load cell 64 consisting of a plate 66 supported by a compressible device 65. On the plate 66 is fixed a hydraulic cylinder 67 for applying a variable static load representing the weight of a vehicle on an axle. The supports 61 are produced with static and dynamic stiffness chosen according to the actual operating conditions and the desired level of performance. For example, in the case where it is desired to optimize the antivibration isolation and limit the deflection of the rail, the supports 61 will be produced with alternating stiffnesses so as to be alternately a relatively rigid support R and a relatively flexible support S.

To verify the anti-vibration behavior of a particular railroad, anti-vibration supports are chosen having static and dynamic stiffness calculated to take into account the actual operating conditions of the railway and they are fixed on the springs 62. On the anti-vibration supports chosen 61 is then arranged a section of track and on this one places the carriage 63 after having adjusted the spacing of the wheels to correspond to the actual spacing of the axles of a bogie of a real rolling vehicle. Sensors connected to conventional measurement and / or recording devices are then installed in a manner known per se to measure the static and dynamic performance of the track: natural frequency, static deflections at the level of the supports, damping of the rail vibrations.

By applying to load cell 64, a load in stages ranging from 0 to 250 kN, for example, and by moving the carriage along the section of track, it is possible to detect the static deflection of the rail to the right of each support.

By applying a static load to the load cell 64 in stages and by shock pulses or vibratory pulses and by moving the carriage along the section of track, the natural frequency of the track system can be noted, the deflections in line with the supports and vibration damping of the rails to the right of each support. The analyzes thus carried out allow the designer of a railway track to be installed to determine in an optimal manner the particularities of the acoustic and anti-vibration insulation elements to be incorporated in the railroad support system in order to optimize the acoustic and anti-vibration insulation. and reduce the transmission of vibration waves to the environment.

Claims (18)

Support system for railroad tracks on roads comprising a slab slab (15) on which the rails (11) of the railroad track are fixed, characterized in that the slab slab (15) rests on a stabilized sand bed (17 ) placed on the bottom of the site trunk, an anti-vibration sole (12) is arranged between each rail and the slab slab, said anti-vibration sole having predetermined static and dynamic stiffness, slabs or road beams (21) extend the along the outer sides of the rails, said road beams being sealed at the edges of the slab slab (15), road slabs (22) are arranged between the rails, and dividing elements (25) fill the spaces between the rails (11) and the road slabs (21, 22), said separation elements being made of a material having static and dynamic rigidities chosen so that the static and dynamic rigidities of the assembly are inf eriors to those of the sole (12) disposed under the rails. Rail support system according to claim 1, characterized in that the separating elements (25) surround the rail shoe (11), each of the above-mentioned separating elements having a lower part (251) which extends under a part of the rail shoe. Rail support system according to claim 2, characterized in that the lower parts (251) of the partition elements (25) are contiguous along oblique faces (252) which extend in an oblique plane with respect to the base of the rail pad. Rail support system according to any one of the preceding claims, characterized in that the road slab (22) between rails rests on leveling supports (24), the void between the road slab and the slab slab being filled by injection of a filling product suitable for the environment. Rail support system according to any one of the preceding claims, characterized in that a layer of anti-vibration material (35) is arranged between the stabilized sand bed (17) and the slab slab (15) Rail support system according to any one of the preceding claims, characterized in that a draining layer (37) is arranged under the slab slab (15). Rail support system according to any one of the preceding claims, characterized in that the rails (11) of the railroad track are fixed on sleepers (13) anchored in the slab slab (15). Rail support system according to claim 7, characterized in that the road slab (22) between rails rests on each side on a crosspiece (13), the void between the road slab and the slab slab being filled by injection of '' a filling product suitable for the environment. Rail support system according to any one of Claims 1 to 6, characterized in that the rails (11) of the railway track are fixed on saddles (33) anchored in the slab slab (15). Rail support system according to any one of Claims 1 to 6, characterized in that the rails (11) of the railway track are fixed on saddles (43) fixed to the slab slab (15), each rail resting on each saddle with possibly the interposition of an anti-vibration cushion. Rail support system according to claim 10, characterized in that each rail (11) rests on each saddle (43) with the interposition of an anti-vibration sole (12) and is fixed to the slab slab (15) by means of devices adjustable fasteners (41) applying an adjustable preload to the anti-vibration sole (12). Rail support system according to claim 11, characterized in that the adjustable fastening devices (41) consist of spring devices (s) reinforced by clamping means. Rail support system according to any one of the preceding claims, characterized in that the elements made of anti-vibration material are chosen so that the successive rail support devices along the track alternately constitute a relatively rigid support and relatively flexible support. Rail support system according to any one of the preceding claims, characterized in that it further comprises at least one prestressing device (51-56) for holding the core of a rail (11) of the railway track and apply to it a predetermined adjustable prestressing force. Method for developing a railroad support system according to any one of the preceding claims, characterized in that it comprises the following steps: (a) placing anti-vibration supports on a support, said anti-vibration supports having predetermined static and dynamic stiffnesses, (b) placing a section of track on the aforementioned anti-vibration supports, (c) application to the track section, of a static load simulating the weight of a vehicle in front applied to an axle, (d) displacement of the load along the section of track, (e) superimposition on said static load of a variable load simulating predetermined loads applied to an axle during the passage of a vehicle on the railway, (f) displacement of the static load combined with the variable load along the track section, (g) recording of the static and dynamic performance of the entire system at the level of each anti-vibration support, the measurements obtained serving to determine the characteristics of the anti-vibration elements to be incorporated in the support devices of the railway. Test bench for implementing the method according to claim 15, characterized in that it comprises a frame carrying a set of equidistant springs (62) each having a low resonant frequency, a set of anti-vibration supports (61) fixed to the springs (62), said anti-vibration supports (61) serving to carry the section of track to be tested, a carriage (63) arranged to be moved along the section of track, a load cell (65) comprising an element compressible and means (67) for applying a variable load to said load cell. Test bench according to claim 16, characterized in that the carriage (63) is mounted on wheels whose spacing is adjustable. Test bench according to either of Claims 16 and 17, characterized in that the anti-vibration supports (61) are produced with alternating stiffnesses so as to be alternately a relatively rigid support and a relatively flexible support.

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