FR2664307A1 - RAIL SUPPORT, AND RAIL TRACK OBTAINED WITH SUCH SUPPORTS. - Google Patents

Abstract

The railway track comprises a relatively hard permanent way, a ballast arranged on the latter, rail supports comprising at least one concrete element (1), and two lengths of rail (3) arranged and fixed parallel on the said supports on one side of the concrete elements, characterised in that a method which is known per se is used for connecting the elements (1) by their lower face (1b) lying opposite the rail (3) to a visco-elastic base pad (4), the novelty being that the visco-elastic material is a substantially non-porous material having a density greater than 0.9 and a resistance to fragmentation and abrasion which is expressed by a weight loss in the concrete cubes coated with the said material of less than 0.2% after 1,500 revolutions of a test-machine drum, the test procedure used here being a routine Los Angeles-type procedure.

Description

RAIL SUPPORT, AND RAIL TRACK OBTAINED WITH SUCH SUPPORTS

  The present invention relates to rail supports, and railways

obtained with these supports.

  More specifically, the invention relates to concrete rail supports, that is to say those comprising at least one concrete part or element, on which a rail is fixed on one side, with the interposition of a elastic sole, and placed on the other side, by its substantially flat underside, on the ballast. Such supports include, according to this definition

  the sleepers which are pieces placed under the rails and perpendicular to

  lairement to these; they are intended to ensure the transmission of loads on the ballast, to maintain the spacing and the inclination of the two rows of rails; a distinction is made between: two-piece sleepers which consist of two pikes in reinforced concrete, connected by a metal spacer, and one-piece sleepers which consist of a single pre-stressed or post-stressed concrete trap, supports for switches and crossings, which are parts placed perpendicular to the track, on which the constituent elements of said devices are fixed; they are intended to ensure the transmission of loads on the ballast and to maintain the geometry of the switchgear; a distinction is made between: monobloc supports which consist of a single piece of prestressed or post-stressed concrete, multiblock supports which consist of two or more reinforced concrete blocks, connected by metal spacers, pikes, studs or stringers; these parts are intended to ensure the transmission of loads on the ballast, to maintain the inclination of the rail, to fix the constituent elements of the switches and crossings, but they do not ensure

  maintaining the spacing of the two rail lines of the same track.

  In the case of a track on ballast, these rail supports rest on a layer of broken stone ballast, itself on a hard foundation layer, or platform This ballast provides the following functions: distribution of concentrated loads on the platform that it receives rail supports,

  vibration damping thanks to its rheological properties.

  Under the action of rolling loads, the friction of the underside of the aforementioned supports, and more specifically of the concrete parts, on the hard stone ballast and with sharp edges, causes attrition of the concrete, with the

  risk of exposing iron or steel frames.

  Such attrition can be limited by placing a sole made of visco-elastic material, of the rubber type, between the ballast and the concrete parts, in contact with their undersides. And this is the starting point for

the present invention.

  The object of the present invention is to determine the technical characteristic or characteristics capable of leading to the desired result, namely to reduce or eliminate the attrition of the concrete parts of the rail supports.

previously defined.

  According to the present invention, it has been discovered that the desired result can be obtained by the combination of two technical characteristics, the first relating to the actual construction of the concrete supports, with the use of a visco-elastic sole, and the second relating to the qualification

  or characteristic of the retained viscoelastic material.

  By viscoelastic material is meant any material having mechanically the properties of a rubber, that is to say both flexible, significantly deformable, and elastic. According to the first characteristic, it appears essential that the sole in viscoelastic material is bonded to the underside of the concrete parts of the support, by at least one adhesion zone in which the material

  visco-elastic is secured to the substrate of the concrete part.

  According to the second characteristic, the visco-elastic material must pre-

  feel a very specific resistance to wear by fragmentation and abrasion, demonstrated or expressed by a "Los Angelès" type test procedure, defined below. According to this procedure, the retained visco-elastic material must have a resistance such that the weight loss of the concrete cubes used according to the above-mentioned procedure, and coated with the visco-elastic material tested, is less than 0.2%, after 1500 revolutions of the

  rotating drum of the testing machine.

  These two characteristics cooperate with each other, to trans-

  effectively put the vibrations or stresses induced by the sole

  rolling loads, and dissipate them in the viscous material

  elastic, due to its good intrinsic resistance characterized as above. In fact, using the test procedure described below and called "unidirectional vibrator", after 200 hours of testing, the support sole according to the invention exhibits no detachment, no tearing or wear leaving

appear the concrete substrate.

  Surprisingly, and as demonstrated by the so-called "unidirectional vibrator" test procedure, supports conforming to this

  invention have also brought the following decisive advantages, with respect to

  screw rolling loads: 1) they significantly reduce the wear of the ballast, that is to say the attrition of the stones against each other

  2) they reduce the compaction of the ballast.

  In total, with supports according to the invention, everything happens as if the energy induced by the rolling loads was absorbed in

  almost all in the pad of elastomeric material according to the invention.

  Reducing ballast wear and packing seems essential for the operation of current railways, on which convoys that are becoming heavier, or faster and faster, such as high-speed trains. Normally, for concrete rail supports, wear is increased compared to that of other types of support, due to the greater inertia of concrete parts or elements, and in particular on hard platforms, or engineering structures with a concrete deck This wear normally causes a deterioration of the geometry of the track, more and more rapid between each leveling-dressing operation, and eventually requires the renewal of the ballast, even that for him

  restore suitable Theological and drainage properties.

  With supports according to the invention, with equal thickness or volume of ballast, the frequency of these operations is reduced, or at equal frequency of

  these operations, the thickness or volume of the ballast can be reduced.

  Finally, the solution according to the invention provides a complete stage

  of elasticity to the railway track, in addition to that already existing between the rail and the sleeper This contributes to reducing the overall stiffness of the rail / sleeper / ballast system This also makes it possible to dissipate in the aforementioned system the vibratory energy generated by rolling loads, in particular when 2 IÉ 4 Ci cannot be absorbed by the platform, for example if the latter

  is a concrete deck of a work of art.

  The present invention also has the additional features

  following, considered individually or in combination: the viscoelastic material is an elastomeric material, natural or synthetic the elastomeric material is a polyurethane, for example as obtained by direct polymerization of a polyetherpolyol and a diisocyanate-dyphenyl methane (DMI) the sole of elastomeric material rises, without discontinuity of material, on the lateral face of the concrete part the adhesion zone of the sole extends along the entire underside of the concrete part

  the sole has a thickness at least equal to 3 mm.

  The supports according to the invention can be obtained without difficulty.

  particular cultivation, according to any one of the following techniques: if the visco-elastic material is a synthetic elastomer, it can be sprayed or cast, applied with a roller brush, in the factory or on a site, on the elements or concrete parts of the supports, possibly

  after deposition of a primer on them, for example a polyurea

  thanne single-component polymerizing on contact with air humidity; for such an application, we prefer a surface finish of concrete of the fine float type of prefabricated plates of visco-elastic material, can be integrated into concrete, during the manufacture of the support, by molding and finally prefabricated plates can be glued on concrete,

  with any suitable adhesive, for example a putty adhesive.

  The present invention is now described in detail, starting with

  by the description of the test procedure used according to the present invention,

  "Los Angeles" type which means that this procedure is similar but not identical in certain respects to the standard procedure of the same name, under the reference NF P 18-573 of AFNOR, the content of which is

  nevertheless incorporated into the present description as necessary.

  This procedure generally consists in rotating in a steel drum, steel balls, calibrated elements of ballast and, concrete cubes uniformly coated, without joints, with a layer of visco-elastic material , especially elastomer, to be tested, and to observe the

  weight loss of these cubes, depending on the number of revolutions of the drum.

  More precisely, the rotated load comprises: 18 steel balls, each having a weight between 0.42 and 0.445 kg 9 concrete blocks, coated with a layer of 5 mm of the material to be tested, each comparable to a cube ; the total weight of these cubes is P a weight P 'of ballast, made of hard silica, equal to P, having a compressive strength of 4000 bars The load is then introduced into a steel drum of a testing machine, with a rotation speed of 33.33 revolutions / minute At regular intervals, for example every 500 revolutions, the machine is stopped, the ballast and the concrete blocks are weighed, and their weight loss is noted, as a percentage relative at P 'and P respectively. The visco-elastic materials suitable according to the invention must lead to a loss of weight of the concrete cubes, according to the procedure explained above, of less than 0.2%, after 1500 turns of the

drum of the testing machine.

  Such a material is for example identified and retained in accordance with the table below according to the procedure described above:

:: CONCRETE: BALLAST: TOTAL WEIGHT

  : covered for 5 min: material: el astom Tre :::

: BAYIR

  Initial weight 2795 g: 500 turns: 2793 g 2790 g: 2625 g 5585 g: 5418 g:: 1000 turns: 1500 turns: 2000 turns: 2500 turns 2793 g 2792 g: 2792 g 2790 g 2530 g 2439 g: 2376 g 2312 g 5323 g 5231 g: 5168 g 5102 g It is, for example, a two-component polyurethane, as sold by the

  BAYER company under the names BAYTEC 308/309 and BAYTEC 310/309.

  This polyurethane is obtained directly, that is to say without solvent, by

  direct polymerization of a polyetherpolyol and DMI (disocyanatedipheny-

  methane) It has a micro-cellular structure This polyurethane can be used with any suitable material for hot spraying, with drying of the spraying air, for example branded material

UNIPRE.

  The use of the visco-elastic material retained in accordance with the test procedure described above is explained by reference to the appended drawings, in which: FIG. 1 represents a crosspiece according to the invention, in two-piece concrete, in cross section the Figure 2 shows a side view of the cross member shown in Figure 1 Figure 3 shows a solid concrete cross member according to the present invention, in cross section Figure 4 shows a side view of the cross member shown in Figure 3 la FIG. 5 represents a support for a track apparatus made of concrete, in accordance with the invention, in cross section. According to Figure 1, a sleeper according to the invention, or rail support, comprises two pieces 1 of reinforced concrete, or blocks, spaced from one another, and connected by a metal spacer 2 On the upper side of the two pikes are fixed respectively two rails 3, in suitable recesses recessed slightly inclined towards each other, and with fixing means not shown An elastic sole not shown is interposed between the

rail and each pike.

  On the lower side 1b of the two pikes 1 respectively, two soles 4 of viscoelastic or elastomeric material are fixed, according to an adhesion zone corresponding to the entire surface of the lower face 1b of the two pikes 1 Consequently, the two blocks 1 are placed on the two flanges 4 respectively, the latter being in contact with the ballast 5; and along the entire underside lb of the pikes 1, the elastomeric material

  retained is integral with the substrate or concrete of said blocks.

  In accordance with FIGS. 3 and 4, the lower face of a single-piece concrete cross member 1 is coated on its lower face 1b with a sole 4 made of elastomeric material, adhering to the substrate of the cross member in two separate adhesion zones, corresponding to two buffers 4 a and 4 b, arranged opposite the two rails 3 respectively. In accordance with FIG. 5, it is a concrete support 1 for a track apparatus. The lower face 1b of support is partially covered by a sole 4 made of visco-elastic material, consisting of different buffers 4 a, 4 b and 4 c, arranged vertically above the rails 3 of the track apparatus respectively. According to FIG. 6, it is a simple concrete block 1, coated on its underside 1b with a sole 4 of elastomeric material. , adhering on one side to the concrete substrate, and in contact with the other

side with ballast 5.

  Supports or crosspieces in accordance with the present invention, as shown in FIG. 1, and coated with BAYTEC material with a thickness of 0.5 cm, were tested according to the procedure known as "unidirectional vibrator",

  explained with reference to Figure 7.

  In a concrete pit 50, there is a ballast load 51, having a minimum DRG hardness coefficient of 17 according to the standard

  NF F 53695 A crosspiece 52 with its pikes 53 is arranged horizontally

  Lement in the pit on the ballast Two rails 54 of limited length are

  each mounted on a pike, parallel to each other, and perpendicular to

  lairement à la traversée Two loads 55 are applied to the two ends respectively of the same rail, five meters on either side of the traverse, to give each rail an arrow of approximately 10 cm, and for

  represent a preload of 40 k N on the cross member A unidirectional vibrator

  tional then transmits to the sleeper to be tested, via a beam and two rails 54, a sinusoidal vertical force of 45 k N, at the

frequency of 50 Hz.

  The test consists in putting the cross-member in vibration, for 200 hours, at the rate of 5 hours per day, and in cycles of 30 minutes, followed by minutes of rest. At the end of the test, the state of the element is observed. tested, in

  the occurrence of the underside of the concrete pike.

  At the end of this test, it is observed that the pad of elastomeric material is partially started by the ballast, but without rupture of the layer of said material, that is to say by preserving the underside of the blocks from any

  contact with the ballast The desired result is therefore obtained.

  This being the case, we observe in passing two essential and surprising results.

  nants: 1) the wear of the ballast remained very limited 2) there was no settlement of the ballast; it was therefore not necessary to restore the initial deflection of the rails by stuffing the ballast.

Claims (5)

CLAIMS II / Rail support comprising at least one concrete part (1), on which a rail (3) is fixed on one side, and placed on the other side, by its substantially flat underside (lb), on a sole (4) of visco-elastic material, characterized in that on the one hand the sole (4) is linked to the underside (lb) of the concrete part, by at least one adhesion zone in which the viscoelastic material is integral with the substrate of said concrete part, and on the other hand said material has a resistance to fragmentation and abrasion, expressed by the loss of weight of concrete cubes coated with said material, according to a procedure of 'Los Angelès' type test, less than 0.2%, after 1500 revolutions of the test machine drum.   2 / Support according to claim 1, characterized in that the material   visco-elastic is an elastomer.   3 / support according to claim 2, characterized in that the elastomer is a polyurethane.   41 Support according to claim 3, characterized in that the polyurea-   thanne is obtained by polymerization of a polyetherpolyol and diisocyanate- diphenylmethane (DMI).   / Support according to claim 1, characterized in that the sole (4) of visco-elastic material rises, without discontinuity of material, on the   side face of the concrete part.   6 / Support according to claim 1, characterized in that the area   adhesion extends along the entire underside (lb) of the concrete part.   7 / Support according to claim 1, characterized in that the se-   melle (4) has a thickness at least equal to 3 mm.   8 / Railway track obtained with supports according to any one of   Claims i to 7, characterized in that it comprises a platform   relatively hard, a ballast placed on the latter, a multiplicity of rail supports distributed in the direction of said rail track, and spaced from each other, and two rows of rail arranged and fixed in parallel on said supports.