Untitled record

Method of constructing a railway line comprising an anti-vibration bed

The present invention relates to a method of constructing a railway track of the type comprising a concrete track slab and anchoring elements for rails of the railway track, said anchoring elements being inserted into said track slab.

From EP-A-1 178 153 is known a method of constructing a railway track in which a track slab is poured and, while the concrete is still fresh, saddles for anchoring the rails of the railway track to. the track slab are inserted into the track slab. The saddles are inserted by means of an inserter straddling the track slab and moving along the track slab.

However, in the railway track obtained by this process, the track slab rests directly on the support slab. When a vehicle takes the railway track, the vibrations caused in the track slab by the passage of this vehicle are thus directly transmitted to the support slab and, by this intermediary, to the environment of the railway track. This is particularly problematic when the railroad tracks along a place sensitive to vibrations, such as a hospital, a school or any other sensitive building such as a concert hall, or a house.

To solve this problem of transmission of vibrations to the environment of the railway track, it is known, in particular from EP-A-1 251 204, to build railway tracks comprising a concrete track slab resting on an anti-vibration bed. . The track slab is then commonly called a “floating slab”.

The method of constructing such a railway line is generally as follows.

The ground is first leveled, then the concrete support slab, known as “clean concrete”, is poured. This support slab serves as a stable support for subsequent work.

Secondly, metal, wooden or concrete formwork is formed on either side of the railway.

Thirdly, a resilient mat is placed on the support slab, between the formwork.

In a fourth step, a separation panel is arranged along the side of each formwork oriented towards the other formwork.

In a fifth step, a first layer of concrete, called a foundation slab, is poured between the forms. This layer is intended to protect the resilient mat, to prevent heavy weight exerted on a localized region of the resilient mat, or a sharp object or tool, from damaging it.

In a sixth step, the rails of the railway, integral with their anchoring elements, are placed at the places they are intended to occupy, and are held in place by means of templates resting on the first layer of the slab. way. At the same time, a metal frame is placed between the formwork.

Finally, a second layer of the track slab is poured between the formwork, so as to envelop the metal reinforcement and to coat the anchoring elements. The templates are removed after the concrete has hardened.

Such a construction method has the drawback of being very slow. In addition, the resilient mat may repeatedly be damaged during construction work, thereby reducing the vibration absorption performance of the mat. Finally, the adjustment of the resilient mat with the damping panels is difficult to achieve, and there is a significant risk of leaving a gap between the resilient carpet and the damping panels, a gap through which the concrete could infiltrate, forming a vibratory bridge. between the track slab and its environment.

An objective of the invention is to allow rapid construction of a railway line comprising an anti-vibration bed. Another objective is to reduce the transmission of vibrations between the track slab and its environment.

To this end, the invention relates to a method of the aforementioned type, in which the railway track further comprises an anti-vibration bed on which the track slab rests, and the method comprises the following steps:

- making the anti-vibration bed,

- casting of the track slab on the anti-vibration bed, and

- Insertion of the anchoring elements into the freshly cast track slab by means of a device for inserting the anchoring elements straddling the track slab and moving along an axis of the railway track.

According to particular embodiments of the invention, the method also has one or more of the following characteristics, taken in isolation or in any technically possible combination (s):

- the method comprises an additional step of producing at least one cracking line of the track slab, oriented substantially perpendicular to the axis of the railway track, after the insertion of the anchoring elements in the track slab,

- the or each cracking line is produced on the surface of the track slab,

- the or each cracking line is produced by sawing the track slab,

- the method comprises an additional step of installing at least one separation panel along a peripheral edge of the track slab,

- the track slab is cast so that an outline of the anti-vibration bed protrudes at the periphery of the track slab and, after the step of installing the or each separation panel, said outline is raised so at least partially covering the or each separation panel,

- the track slab is formed from a single layer of concrete,

- the track slab has no metal reinforcement,

- the step of making the anti-vibration bed includes the following sub-steps:

o providing a resilient mat, o cutting the resilient mat into resilient slabs, each resilient slab having a reference axis parallel to the direction of elongation of the resilient mat, and o laying resilient slabs so that they are juxtaposed together. to each other along the axis of the railroad track, the reference axis of each resilient slab being oriented substantially perpendicular to the axis of the railroad track,

- the anti-vibration bed has a width, taken in a direction perpendicular to the axis of the railway track, less than the narrowest track of the insertion device,

- the track slab is poured using a slipform paver,

- the anti-vibration bed has a width, taken in a direction perpendicular to the axis of the railway track, less than the narrowest track of the slipform paver,

the method comprises an additional step of guiding the insertion device, said guiding step comprising the following sub-steps:

o establishment of topographic points and recording of the coordinates of these points in a reference frame, o setting up of a measuring station near the railway track and determination of the position of the measuring station in the reference frame, taking as reference to the at least one of said topographic points, o determination, using said measuring station, of the distance and of the angle separating the insertion device from the measuring station, o calculation of the position of the insertion device using the measured distance and the determined position of the measuring station, and o displacement of the insertion device so that each anchoring element is opposite an insertion position of the anchoring element in the track slab,

- The or each separation panel is a damping panel.

Other characteristics and advantages of the invention will become apparent on reading the description which follows, given solely by way of example and made with reference to the appended drawings, in which:

Figure 1 is a schematic sectional view of a railway track obtained by means of a construction method according to the invention, Figure 2 is a perspective view of the railway track of Figure 1, during a first step of the construction process, Figure 3 is a view similar to that of Figure 1, during a second step of the construction process, and Figure 4 is a perspective view of the railway track of Figure 1, during construction. 'a third step of the construction process.

In the following, the terms of orientation are to be understood with reference to an orthogonal reference mark represented in Figures 1 to 4, and in which one distinguishes:

a longitudinal direction X, horizontal, oriented from the rear to the front and parallel to an axis 2 of the railway track 10, a transverse direction Y, horizontal, oriented from the right to the left and perpendicular to the longitudinal direction X, and a vertical direction Z, oriented from the bottom to the top.

The railway track 10, shown in Figure 1, comprises a support slab 12, called a cleanliness slab, made of concrete, an anti-vibration bed 14, placed on the support slab 12, a concrete track slab 16, resting fully on the anti-vibration bed 14, and a plurality of anchoring elements 18 for the rails 20 of the railway 10, inserted in the track slab 16. In the example shown, the railway track 10 further comprises environmental concrete 22, transversely framing the track slab 16, and partition panels 24, each interposed between the track slab 16 and the environmental concrete 22 .

The support slab 12 has a lower face 30, in contact with the ground S, and an upper face 32, opposite the lower face 30, which is substantially flat. It has a small thickness, taken between its lower 30 and upper 32 faces. It has sufficient rigidity to allow the maneuvering of construction machinery on its upper surface 32 without breaking.

The anti-vibration bed 14 is adapted to prevent the transmission of vibrations between the track slab 16 and the support slab 12. For this purpose, the anti-vibration bed 14 is formed of a plurality of resilient slabs 34 (Figure 2 ) juxtaposed to each other. Each tile 34 is for example cut from a DFMA-L10-RR-F carpet, marketed by CDM.

The anti-vibration bed 14 is continuous, and does not have a through orifice.

The track slab 16 has a lower face 40 in contact with the anti-vibration bed 14, an upper face 42, opposite and substantially parallel to the lower face 40, and a peripheral edge 44 connecting the lower face 40 to the upper face 42 The track slab 16 thus has the shape of a prism.

The track slab 16 is formed from a single layer of concrete, and is, in the example shown, devoid of metal reinforcement. It should be noted that, since the Pavement Structures Sizing Manual (LCPC / SETRA 1994) does not present a configuration with a single-layer slab, it was necessary to design a specific track slab 16 adapted to the anti-vibration bed 14 to limit the transmission of vibrations through the anti-vibration bed 14, while ensuring good resistance and good aging of the track slab 16. Satisfactory performance of track slab 16 was obtained by making a track slab 16 40 cm thick, with class C35 / 45 concrete.

Each anchoring element 18 is, in the example shown, an anchoring saddle, comprising a plate 50 of rigid material, such as cast iron or a plastic material, two anchors (not shown) each having a threaded rod allowing to fix a rail 20 on the saddle 18 by nuts (not shown), and two sealing rods 54 each having a generally cylindrical shape adapted to ensure the retention of the saddle 18 in the track slab 16 once it has hardened . The saddles 18 are aligned transversely in pairs, each pair comprising a right saddle and a left saddle. The right saddles are aligned longitudinally with each other, and the left saddles are aligned longitudinally with each other.

As a variant, each anchoring element 18 is a cross member.

Each rail 20 is oriented substantially longitudinally. It is fixed to the anchorages 52 of each saddle 18 by means of nuts (not shown).

The rails 20 are equidistant from the axis 2 of the railroad 10.

The environmental concrete 22 is made in a single layer. It has a thickness substantially equal to that of the track slab 16.

Each separation panel 24 is attached to the peripheral edge 44 of the track slab 16. It extends from the support slab 12 to the upper face 42 of the track slab 16, and protrudes above said face. upper 42. The meeting of the separation panels 24 covers the entire peripheral edge 44.

Each separation panel 24 typically consists of a damping panel, for example a polystyrene panel preferably having a thickness between 10 and 15 mm.

A contour 56 of the anti-vibration bed 14 protrudes at the periphery of the track slab 16, preferably over more than 90% of the periphery of the track slab 16. This contour 56 is oriented substantially vertically and covers a lower section 58 of each partition panel 24. Thus, there is no orifice left free between the anti-vibration bed 14 and the separation panels 24, so that the track slab 16 is perfectly isolated from its environment thanks to the anti-vibration bed 14 and the partition panels 24.

In the example shown, the railway track 10 further comprises a surface coating 60. This surface coating 60 defines an upper surface 62 of the railway track 10. It covers the track slab 16 and the surrounding concrete 22. In the example shown, the surface coating 60 is made of concrete. As a variant, it is made of bitumen or paving stones or grass.

Each rail 20 is flush with the top surface 62.

Each partition panel 24 separates the part of the surface covering 60 covering the track slab 16 from the part of the surface covering 60 covering the environmental concrete 22. In other words, each partition panel 24 extends between the part of the surface coating 60 covering the track slab 16 and the part of the surface coating 60 covering the surrounding concrete 22. This prevents vibrations caused by the passage of a vehicle on the track 10 from being transmitted to the environment of the track slab 16 via the surface coating 60.

A seal 64 covers each partition panel 24. This seal 64 is flush with the upper surface 62. It is housed between the part of the surface covering 60 covering the track slab 16 and the part of the surface covering 60. covering environmental concrete 22.

A method of constructing the railway track 10 will now be described, with reference to Figures 2 to 4.

First, the ground S is leveled. Then concrete is poured on the leveled ground S, so as to form the support slab 12. A rule (not shown) is passed over the freshly poured support slab 12, so as to ensure the flatness of the upper face 32.

It will be noted that the expression “freshly cast” used here and in the following is to be understood as designating a concrete slab in which the concrete remains sufficiently fluid to be easily shaped. In the case of a concrete slab cast by means of a slipform paver, said slab can generally be considered to have been freshly poured up to about an hour after the slab has been poured.

A resilient mat (not shown), for example a DFMA-L10-RR-F resilient mat from CDM is then provided. This mat is cut to form the resilient tiles 34.

Each slab 34 is cut along the length of the resilient mat. In other words, each slab 34 is constituted by a longitudinal section of the resilient mat, taken between two lines of cutouts, each oriented in a transverse direction of the resilient mat. Each slab 34 is thus substantially rectangular and has a first dimension, taken in the transverse direction of the resilient mat, equal to the width of the resilient mat.

Each slab 34 has a reference axis, corresponding to the direction of elongation of the resilient mat before cutting said slab 34. Each slab 34 is cut so that its dimension along said reference axis, called second dimension, is substantially equal to the second dimension of each other slab 34. Said second dimension is in particular chosen so as to be slightly greater than the width of the track slab 16.

As visible in Figure 2, the resilient slabs 34 are then placed on the support slab 12. Each resilient slab 34 is oriented so that its reference axis extends substantially transversely, being centered on axis 2 of the railway track 10. Each resilient slab 34 is juxtaposed with another resilient slab 34 laid previously, preferably so as to partially cover the other resilient slab 34, and said resilient slabs 34 are linked to one another by a connecting means 66, typically an adhesive tape.

The anti-vibration bed 14 is thus obtained, said anti-vibration bed 14 having a width equal to the second dimension of each resilient slab 34, and a length substantially equal to the sum of the first dimensions of the resilient slabs 34. By virtue of this process For making the anti-vibration bed 14, it is easy to control the width of the anti-vibration bed 14. In addition, this method simplifies the making of the anti-vibration bed 14 in the bending zones of the railway track 10.

Optionally, the anti-vibration bed 14 is fixed to the support slab 12.

Referring to Figure 3, the track slab 16 is then cast on the anti-vibration bed 14.

For this purpose, a sliding formwork machine 70 is brought to the site. This machine 70 comprises a sliding formwork 72, means (not shown) for feeding the concrete sliding formwork 72, a frame 74, and means 76 for moving the machine 70 along the railway track 10. The displacement means 76 comprise support members 78, movable relative to the frame 74 and defining a contact surface of the machine 70 with the ground S, and a mechanism (not shown) for driving said support members 78. In the example shown, each support member 78 is a caterpillar. As a variant, at least one support member 78 is a wheel.

The slipforming machine 70 is adapted to overlap the anti-vibration bed 14. For this purpose, the narrowest track of the machine 70, that is to say the smallest transverse component of the distances of the support members 76 to each other, is greater than the width of the anti-vibration bed 14.

The slipforming machine 70 is arranged at one end of the anti-vibration bed 14 so as to overlap the anti-vibration bed 14, that is to say so that its support members 76 rest on the support slab 12. transversely on either side of the anti-vibration bed 14. Concrete is poured by gravity upstream of the slip formwork 72, and the machine 70 is advanced along the axis 2 of the railroad 10 so that the slip form 72 comes to mold the poured concrete, thus forming the track slab. 16.

The track slab 16 is cast so as to leave the contour 56 of the anti-vibration bed 14 free.

The anchoring elements 18 are then inserted into the freshly cast track slab 16. For this purpose, a device 80 (Figure 4) for inserting the anchoring elements 18 is brought to the site.

Referring to Figure 4, the insertion device 80 comprises a frame 82, a member 84 for inserting the anchoring elements 18, mounted on the frame 82, support members 86, movably mounted on the frame 82 and defining a contact surface of the device 80 with the ground S, and a mechanism (not shown) for driving at least part of the support members 86. In the example shown, each support member 86 is a wheel. As a variant, at least support member 86 is a caterpillar.

The insertion device 80 is adapted to overlap the anti-vibration bed 14. For this purpose, the narrowest path of the device 80, that is to say the smallest transverse component of the distances of the support members 86. to each other, is greater than the width of the anti-vibration bed 14.

The insertion member 84 is mounted at the rear of the frame 82. It is, in the example shown, constituted by a motorized arm in rotation and in translation along the three axes X, Y, Z, provided with a mechanism allowing movements of the arm 84 with great precision.

The arm 84 has a general H shape and supports on its lower part two jacks (not shown) at the end of which are fixed two of the anchoring elements 18 intended to be inserted into the track slab 16. The two elements d 'anchor 18 are maintained by the arm 84 at a distance from each other corresponding to the template of the railroad 10. The arm 84 is equipped with a double inclinometer (not shown) permanently measuring the orientation of the arm 84 with respect to the X and Y axes.

The arm 84 carries on its rear face at least two, in the example shown three, reflectors 90 intended to cooperate with a measuring station 92 installed at the edge of the railway track 10. A reflector 90 is also mounted on the roof of the device. 80.

The measuring station 92 is, in the example shown, installed on a tripod vertically to a terminal 94 for a topographic survey. The positioning of the measuring station 92 on the terminal 94 is carried out very precisely, by placing the measuring station 92 in line with the terminal 94, and the coordinates of the measuring station 92 are determined by measuring the distance vertical separating the measuring station 92 from the terminal 94 using a rod (not shown).

The measuring station 92 comprises a laser distance measuring device equipped with an emitting optic and a receiving optic making it possible to know with very high precision the distance and the angle separating the measuring station 92 from each reflector 90. The laser measuring device used is for example the device marketed under the reference TC / TCA 2003 by the company LEICA.

The measuring station 92 also comprises a radio transmitter 96 for sending the results of the measurements carried out at each instant by the laser measuring device in the direction of a receiver 100 carried by the device 80. This receiver 100 is connected to an on-board computer 102. on device 80.

The computer 102 is programmed to calculate the exact position of the arm 84 in space from the information sent by the measuring station 92 and the known position of the topographic survey terminal 94. It comprises a memory (not shown) storing the coordinates of the insertion points of the anchoring elements 18 in the track slab 16. It is connected to a controller (not shown) which controls the movement of the arm 84 and the jacks, as well as the drive mechanism of the support members 86.

The insertion device 80 is positioned so as to overlap the freshly cast track slab 16 and the anti-vibration bed 14, i.e. so that its support members 86 rest on the support slab 12 transversely. on either side of the anti-vibration bed 14 and of the track slab 16. The laser distance measuring device is then oriented towards the insertion device 80, so as to measure the distance and the angle separating the measuring station 92 from each reflector 90.

The result of these measurements is sent immediately by radio waves from the transmitter 96 to the computer 102, which then calculates the exact position of the insertion device 80 in space from the data sent by the measuring station 92 and of the known position of the measuring station 92.

The computer 102 compares this position of the insertion device with the coordinates of the insertion points of the anchoring elements 18 stored in its memory, and accordingly controls the drive mechanism of the support members 86 so as to move the device. insertion 80 along the railway track 10 until bringing the arm 84, stationary in a rest position, substantially in line with the insertion points of the anchoring elements 18.

Once the insertion device 80 immobilized, the computer 102 verifies the position of the arm 84 in space, from the data transmitted by the measuring station 92, and implements the method described in FR-A-2 897 622 to control the movement of the arm 84 along the six degrees of freedom so as to bring, with very great precision, the anchoring elements 18 to the right of their insertion points. The jacks are then actuated to insert the anchoring elements 18 into the track slab 16 not yet hardened according to a method described in EP-A-0 803 609.

Once the two anchoring elements 18 have been inserted, the arm 84 is returned to the rest position. The computer 102 then searches its memory for the coordinates of the next points where the anchoring elements 18 are to be inserted, then repeats the previous steps.

When all the anchoring elements 18 have been inserted into the track slab 16, the latter is left to stand for a few hours. Then, between four and twenty-four hours after the casting of the track slab 16, a plurality of crack lines 110 (for the sake of clarity, a single crack line 110 is shown in Figure 4) are made in the slab. track 16.

Each cracking line 110 is oriented transversely and is located between two anchoring elements 18 arranged successively in the longitudinal direction X.

Each cracking line 110 is produced on the surface of the track slab 16, by sawing the track slab 16.

The cracking lines 110 are produced at regular distance intervals in the track slab 16. Preferably, for each pair of consecutive cracking lines 110, the distance separating said cracking lines 110 is less than 10 m, in particular less than 6 m.

These cracking lines 110 make it possible to control the location of the cracks occurring in the track slab 16 during the drying of the concrete constituting it.

Later, the partition panels 24 are arranged along the peripheral edge 44 of the track slab 16. The partition panels 24 are juxtaposed to each other, so as not to leave a gap between the panels 24. The panels 24 are juxtaposed. panels 24 are attached to track slab 16, typically by means of an adhesive (not shown).

The contour 56 of the anti-vibration bed 14 is then straightened and applied against the separation panels 24, so as to cover the lower section 58 of each separation panel 24. The contour 56 is immobilized in this position, typically by being fixed to each partition panel 24.

The environmental concrete 22 is then poured transversely on one side and the other of the track slab 16, according to a method known to those skilled in the art, the rails 20 are fixed to the anchoring elements 18, and the seals 64 are positioned.

Finally, the surface coating 60 is applied to the track slab 16 and to the environmental concrete 22.

By virtue of the method described above, the railway line 10 can be constructed easily and quickly.

In addition, by virtue of this method, the anti-vibration bed 14 does not run the risk of being damaged during the construction work of the railway. The railway track 10 can therefore have good acoustic properties.

Finally, this method makes it possible to ensure precise positioning of the railway track 10.