HK1112033A - Railway sleeper - Google Patents

Description

Track sleeper

Technical Field

[01] The invention relates to a rail sleeper (also called sleeper) of the type comprising:

[02] -a rigid block having a bottom face and a top face for receiving at least one longitudinal rail;

[03] -a casing for receiving said rigid block, in the form of a rigid shell comprising a bottom and a perimetric frame surrounding said bottom; and

[04] -an elastic pad arranged between the bottom surface of the rigid block and the bottom of the casing.

Background

[05] Such sleepers are often used for laying rails without ballast, for example in or on structures such as tunnels or viaducts, where the sleepers are supported by foundations or slabs.

[06] EP-A-0919666 describes ｃA sleeper of this type. The rigid casing is embedded in the concrete slab and forms a rigid device therewith.

[07] Each rail typically rests on a resilient support element arranged between each rail and the rigid block. These elastic support elements thus form a first elastic stage. They can be installed when the rails are laid, or they can be pre-installed, for example when the sleepers are assembled.

[08] The elastic pad placed between the block and the rigid casing forms a second elastic stage.

[09] Vibrations generated on the rail when the train passes are substantially damped in the first and second spring levels.

[10] However, the damping of mechanical vibrations as is known at present when a train passes on such a track system is not entirely satisfactory. For example, both the cut-off frequency and the intervening gain are greater than these parameters of the rail system on the float plate.

Disclosure of Invention

[11] It is an object of the present invention to improve the vibration damping properties of the aforementioned ties while limiting the fatigue and stresses to which the rail system is subjected, particularly in the frequency range up to 250 hertz (Hz), which is considered to be damaging to the surrounding structures.

[12] To this end, the invention provides a sleeper of the above-mentioned type, characterized in that the dynamic stiffness k2 of the resilient tie plate is between 6 kilonewtons per millimeter (kN/mm) and 10 kilonewtons per millimeter (kN/mm), preferably between 6kN/mm and 8 kN/mm.

[13] According to other features of the invention:

[14] -the resilient pad has a substantially flat top surface and a substantially flat bottom surface;

[15] -said rigid block has four perimetric surfaces connecting said top surface to said bottom surface, said sleeper comprising an elastic gasket arranged between each perimetric surface of said rigid block and the perimetric frame of said casing;

[16] -the elastic pads comprise at least two elastic pads with a longitudinal dynamic stiffness comprised between 20kN/mm and 25kN/mm, and at least two elastic pads with a transverse dynamic stiffness comprised between 15kN/mm and 18 kN/mm;

[17] -said sleeper has, on the top face of said rigid block, an elastic support element with a dynamic stiffness comprised between 120 and 300kN/mm, preferably between 200 and 300kN/mm, designed to receive a rail resting thereon;

[18] -said sleeper comprises a single block and a single casing;

[19] -the weight of said rigid block is between 350kg and 450kg, preferably between 400kg and 450 kg;

[20] -said sleeper comprises: two rigid blocks; two respective casings associated with said rigid blocks; and a lateral spacer interconnecting the two rigid blocks; and is

[21] -the weight of each rigid block is between 100kg and 150kg, preferably between 130kg and 150 kg.

[22] The invention also provides a rail section, characterized in that it comprises a tie as described above, and at least one rail supported on said tie.

Drawings

[23] The invention may be better understood by reading the following description, given by way of example and with reference to the accompanying drawings, in which:

[24] figure 1 is a schematic cross-section of a track section in a first embodiment;

[25] figure 2 is a more detailed schematic section view of the sleeper shown in section in figure 1;

[26] fig. 3 is a schematic longitudinal section of the sleeper shown in fig. 1 and 2;

[27] FIG. 4 is a view simulating the track section of FIG. 1;

[28] fig. 5 is a graph showing the acoustic performance of the tie according to the invention; and

[29] fig. 6 is a view similar to fig. 1 and showing a track segment of a second embodiment.

Detailed Description

[30] A track section 2 according to a first embodiment of the invention is schematically shown in fig. 1. The rail section 2 comprises two longitudinal rails 4 fixed to sleepers 8. The sleeper 8 comprises a single concrete block 9 and two elastic support elements 10 arranged between each track 4 and the concrete block 9.

[31] According to convention, the longitudinal rail 4 is determined to serve as a reference for the longitudinal direction.

[32] The resilient support element 10 is substantially in the form of a cuboid. In the embodiment shown in fig. 1, their width is substantially equal to the width of the base of the rail 4 and their length is substantially equal to the width of the block 9.

[33] The elastic support elements 10 are received in respective grooves 12 in the block 9. Each groove 12 has a substantially rectangular profile in cross-section. The width and length of each groove 12 is, in the embodiment shown in fig. 1, substantially equal to the respective width and length of the elastic support element 10.

[34] For example, the elastic support element 10 is adhesively connected to the sleeper 8.

[35] Each track 4 is coupled to the block 9 by means of a track fastener (not shown) which prevents any lateral movement of the track with respect to the block 9 and secures the track 4 with the block 9 and each resilient support element 10.

[36] Throughout the description below, the dynamic stiffness is always considered as constant and substantially equal to 130% of the static stiffness, based on the frequency range considered (less than or equal to 250 Hz).

[37] The resilient support member 10 forms a first resilient stage 14 with a vertical dynamic stiffness of k1 shown in the model of fig. 4. Each rail 4 is modeled to be suspended on a first end of a spring 16 with a dynamic stiffness k 1. A second end of the spring 16 is connected to the block 9.

[38] The dynamic stiffness k1 of each elastic support element 10 is in the range of 120kN/mm to 300kN/mm, and preferably in the range of 200kN/mm to 300 kN/mm. For example, the materials used for each elastic support element 10 are: rubber, polyurethane, or any other resilient material.

[39] The sleeper 8 shown in fig. 1 is shown in detail in fig. 2 and 3 and comprises a casing 20 for receiving the blocks 9, an elastic pad 22 arranged in a substantially horizontal plane between the blocks 9 and the casing 20, and four elastic pads 24, 26 arranged in a substantially vertical plane between the blocks 9 and the casing 20.

[40] The block 9 is substantially in the form of a rectangular parallelepiped and it essentially comprises: a top surface 32; a substantially flat bottom surface 34 with which it rests; and four peripheral surfaces 36, 38 connecting the top surface 32 to the bottom surface 34 by rounded edges 44 and beveled corners 46, respectively. The circumferential surfaces 36, 38 comprise two longitudinal circumferential surfaces 36 and two transverse circumferential surfaces 38.

[41] Each peripheral surface 36, 38 has a substantially planar lower portion 36A, 38A and a substantially planar upper portion 36B, 38B, and a substantially planar intermediate portion 36C, 38C interconnecting each lower portion 36A, 38A and its corresponding upper portion 36B, 38B. The longitudinal upper portion 36B and the lateral upper portion 38B converge upwardly toward each other. The longitudinal lower portion 36A and the transverse lower portion 38A converge downwardly toward one another. The longitudinal intermediate portion 36C and the transverse intermediate portion 38C converge downwardly toward each other to form an angle with respect to the vertical plane that is greater than the angle formed by each respective lower portion 36A, 38A.

[42] The block 9 is chosen to have a particularly high weight. Its weight is in the range of 350kg to 450kg, and preferably between 400kg to 450 kg. The weight of the block 9 is usually increased by adding metal elements in the concrete.

[43] The casing 20 is formed by a substantially rigid shell. The case 20 generally includes a base 48 and a continuous perimeter frame 50 surrounding the base 48.

[44] The bottom 48 has a substantially flat rectangular top surface 52.

[45] The perimeter frame 50 of the case 20 has four panels 54, 56. These four plates 54, 56 comprise two longitudinal plates 54 respectively associated with the longitudinal surfaces 36 of the block 9 and two transverse plates 56 respectively associated with the transverse surfaces 38. Each plate member 54, 56 has a respective inner surface 62, 64. Each inner surface 62, 64 includes a recess 66, 68, substantially rectangular in shape, each for receiving a respective resilient pad 24, 26.

[46] The housings 66, 68 are substantially parallel to the corresponding lower portions 36A, 38A of the peripheral surfaces 36, 38 of the block 9. Each pocket 66, 68 has a rectangular perimeter defined by a continuous perimeter shoulder 66A, 68A. Each pocket 66, 68 also has substantially the same height and the same length as its associated lower portion 36A, 38A.

[47] Each inner surface 62, 64 has an upper portion 62A, 64A which is flat and inclined with respect to the vertical, with an inclination substantially equal to or greater than that of the corresponding intermediate portion 36C, 38C of the peripheral surface 36, 38 of the block 9. The height of the upper portions 62A, 64A is substantially the same as the height of the associated intermediate portions 36C, 38C of the block 9.

[48] The upper portions 62A, 64A of the inner surfaces 62, 64 of the plate members 54, 56 are connected to a continuous top edge 70 of the bezel 50. In the embodiment shown in fig. 2 and 3, the top edge 70 has two fingers for holding a continuous sealing gasket 72. For example, the gasket 72 is made of natural or synthetic rubber. It implements a seal between the block 9 and the casing 20 without preventing the movement of the block 9 in the casing 20. The sealing gasket 72 may also be obtained by casting a material such as silicone or polyurethane in the form of a continuous bead.

[49] The rigidity of the sleeve 20 is enhanced by ribs 74 formed in a convex manner on the exterior of the plates 54, 56 and partially under the bottom 48. For example, they are integrally molded with the case 20. These ribs 74 may be of any suitable shape and position relative to the sleeve 20 in ｃA manner known in the art, in particular from EP- ｃA-0919666. In the embodiment shown in figures 2 and 3, they have notches 76 which enable the sleeve 20 to be fixed to the strength member. The ribs 74 are at least partially embedded in the concrete when the track is laid. They thus serve to fix the casing 20 to the filling concrete.

[50] In the embodiment shown in fig. 2 and 3, the casing 20 can be made as a one-piece moulding. In ｃA manner not shown, the case 20 can be made by assembling together ｃA plurality of partial shells, as disclosed in the prior art (for example EP- ｃA-0919066). As the monolithic sleepers 8 in the first embodiment of the invention, they may comprise, for example, two half shells at each end, and an intermediate shell interconnecting the two end half shells.

[51] The casing 20 is made of, for example, a molded thermoplastic material or resin concrete.

[52] The resilient pad 22 is substantially in the form of a rectangular parallelepiped and it has substantially flat top and bottom surfaces in order to minimize the mechanical stresses to which the resilient pad 22 is subjected and to avoid fatigue problems. Its length and width are substantially equal to the length and width, respectively, of the bottom surface 34 of the block 9.

[53] Its thickness is between 10 and 20 millimeters (mm), preferably between 16 and 20 mm. The elastic pad 22 is thus retained in the elastic region; which substantially corresponds to a maximum deformation of less than or equal to 40%. The amount of deformation is the ratio of the change in thickness of the resilient pad 22 between the free state and the loaded state.

[54] The resilient pad 22 forms a second spring stage 78 with a vertical dynamic stiffness of k2 as shown in the model of fig. 4. The rigid block 9 is modeled to be suspended on the first ends of two springs 80 with a dynamic stiffness k 2. A second end of the spring 80 is connected to the sleeve 20.

[55] The resilient pad 22 of the present invention has a dynamic stiffness k2 that is less than the dynamic stiffness of conventionally used devices. The dynamic stiffness k2 is between 6kN/mm and 10kN/mm, and preferably between 6kN/mm and 8 kN/mm.

[56] For example, the elastic pad 22 is made of a porous elastic material.

[57] In the preferred embodiment, the vertical dynamic stiffness k2 of the resilient pad 22 is substantially uniform throughout its area.

[58] In another embodiment, the vertical dynamic stiffness k3 of the resilient pad 22 in the middle region of the block 9 is less than or equal to k 2. The middle zone comprises the middle of the block 9 and extends over substantially half the area of said block 9 from each side of the middle of the block 9 laterally towards the ends. Since this intermediate region is less stressed, it is possible to use more elastic and therefore cheaper materials therein.

[59] The resilient pad 22 is free to rest against the bottom 48 of the case 20. It can be easily removed from the sleeve 20.

[60] Advantageously, tie 8 also has a substantially incompressible thickness member 82, as shown in fig. 2 and 3.

[61] The thickness member 82 is substantially in the form of a rectangular parallelepiped. Having a length and width substantially equal to the length and width of the top surface 52 of the bottom 48 of the sleeve 20. Its thickness is less than or equal to 10mm and preferably between 2mm and 4 mm.

[62] The thickness member 82 freely rests on the bottom 48 of the case 20. It can be easily removed from the sleeve 20 or it can be added to the sleeve 20 to adjust the flatness of the rail.

[63] Advantageously, the resilient pad 22 is freely supported on the thickness member 82.

[64] The surface of the thickness member 82 is rough enough to avoid the elastic pad 22 from sliding in the casing 20. Such roughness is obtained, for example, by serrations, diamond tips or barbs.

[65] Each resilient pad 24, 26 has an outer surface 24A, 26A and an inner surface 24B, 26B, and four peripheral surfaces.

[66] The outer surfaces 24A, 26A and the inner surfaces 24B, 26B are substantially the same size and their profile is substantially rectangular.

[67] The length and width of the outer surfaces 24A, 26A and the inner surfaces 24B, 26B are substantially equal to the length and width of the corresponding sockets 66, 68, respectively, in the perimeter frame 50 of the sleeve 20.

[68] The resilient pads 24, 26 face in the corresponding sockets 66, 68. For example, they are retained by friction between the peripheral surface of the resilient pads 24, 26 and the peripheral shoulder 66A, 68A of each socket 66, 68. The resilient pads 24, 26 can thus be easily removed.

[69] Each resilient pad 24, 26 may also be retained by a snap fit. For example, the sockets 66, 68 may have grooves and the resilient pads 24, 26 may have complementary grooves.

[70] The thickness of the resilient pads 24, 26 is greater than the thickness of the sockets 66, 68 so that they project relative to the shoulders 66A, 68A.

[71] The inner surfaces 24B, 26B are only pressed against the corresponding bottom portions 36A, 38A of the peripheral surfaces 36, 38 of the rigid block 9.

[72] As shown in fig. 2 and 3, the inner surfaces 24B, 26B are provided with grooves, thereby increasing their flexibility.

[73] The dynamic stiffness of the resilient pads 24, 26 is between 12kN/mm and 25 kN/mm. For example, they may be made of rubber, polyurethane or any other resilient material.

[74] The longitudinal pads 24 corresponding to the longitudinal peripheral surfaces 36 are subjected to a greater force than the transverse pads 26 corresponding to the transverse peripheral surfaces 38. Advantageously, therefore, the longitudinal spacers 24 may be selected to have a dynamic stiffness greater than that of the transverse spacers 26. Thus, for example, the longitudinal pads 24 have a dynamic stiffness of between 20kN/mm and 25kN/mm, while the transverse pads 26 have a dynamic stiffness of between 15kN/mm and 18 kN/mm.

[75] Under normal operating conditions, the elastic inserts 24, 26 keep the block 9 clear of the inner surfaces 62, 64 of the casing 20.

[76] The resilient pads 24, 26 thus provide horizontal cushioning for the block 9. This horizontal cushioning is separated from the vertical cushioning achieved by the resilient support member 10 and the resilient pad 22.

[77] It should be observed that: the number of elastic pads is not limited. For example, tie 8 may have two lateral pads 34 side by side on each side of block 9.

[78] Fig. 5 shows the acoustic performance of a prior art sleeper and a sleeper according to the invention. Fig. 5 shows the insertion gain as a function of frequency. The intervention gain in this embodiment is the ratio between the measured magnitude (velocity, acceleration, pressure, etc.) when the elastic pad is included and the magnitude obtained when the elastic pad is not included, this ratio being expressed in decibels (dB) (see french standard ISO 14837-1: 2005). In the embodiment described, this is the force exerted on the sleeve 20. The reduction in magnitude (value of the magnitude) is represented by the intervening gain with a negative sign.

[79] Further, the cutoff frequency is a frequency: above this frequency, a decrease in intervening gain is observed.

[80] k1dyn is the dynamic stiffness of the resilient support element 10, k2dyn is the dynamic stiffness of the resilient pad 22, and M is the weight of the block 9.

[81] A curve representing the insertion gain as a function of frequency-wherein: k2dyn 21.3 million newtons per meter (MN/M), M200 kg and k1dyn 150MN/M constitute a reference curve S1 showing the performance of the prior art. The second curve represents the tie performance of the present invention, where k2dyn is 8MN/M, M is 400kg, and k1dyn is 270 MN/M.

[82] In the range of 0 to 10Hz, the vibration damping performance is substantially the same. In the range of 10Hz to 25Hz, the insertion gain is slightly larger than the curve S1 by a few decibels (dB). In the range of 25Hz to 250Hz, the intervening gain ratio curve S1 is in decibels (dB).

[83] Furthermore, the cut-off frequency is lower than that of the curve S1 (the former is 20Hz instead of 32 Hz).

[84] Thus, the performance of the tie of the present invention is clearly superior in the range of 25Hz to 250 Hz.

[85] In a second embodiment shown in fig. 6, the tie 108 comprises two rigid blocks 109 interconnected by a spacer 184. Since two-piece sleeper 108 is very similar to single-piece sleeper 8, the same reference numerals as used in fig. 1 to 4 are used in fig. 6, but increased by 100.

[86] The shroud 120 is of a length suitable to receive the block 109. The same applies to the lateral spacers 126 and the elastic pad 122. Figures 2 and 3, which show a single block tie 8, are also fully applicable to the representation of tie 108.

[87] The main differences between the single block sleeper 8 and the two block sleeper 108 are: there is a spacer 184 that penetrates into both blocks 109.

[88] A decrease in the dynamic stiffness k2 of the resilient pad 122, and/or an increase in the weight of the block 109, produces a large longitudinal bending movement.

[89]Thus, the shape of the spacer 184 is adapted to obtain a large second area moment. For example, it may be in the form of an angle or a cylinder. For example, the spacers 184 have a dimension in the range of 800 square millimeters (mm)²) To a cross-sectional area in the range of 1500 square millimeters and a thickness of between 6mm and 10 mm. For example, it is made of steel in accordance with standard EN 13230-3.

[90] The weight of each block 109 is between 100kg and 150kg, preferably between 130kg and 150 kg.

[91] It should be observed that: monolithic sleeper 8 is particularly good at withstanding the additional mechanical stresses caused by the present invention.

[92] It should be understood that: for the tie of the present invention, the reduction of the dynamic stiffness k2 of the resilient pads 22, 122 serves to obtain better vibration damping performance, in particular by lowering the cut-off frequency and reducing the intervening gain between 25Hz and 250 Hz.

[93] For a given dynamic stiffness k2 of the resilient pad 22, 122, an increase in the weight of the mass 9, 109 may also lower the cut-off frequency and thus may improve the performance of the sleeper 8, 108 at low frequencies. Above a certain weight, however, the mechanical stresses to which sleepers 8, 108 are subjected will become too great.

[94] The increase in the dynamic stiffness k1 of the flexible support element 10, 110 reduces the insertion gain in the range of 200Hz to 250Hz and shifts the resonant frequency, which is the frequency at which the insertion gain is observed to increase, towards higher frequencies.

[95] The present invention can thus approach the vibration attenuation performance obtained with a floating plate with a cut-off frequency between 14Hz and 20Hz and an intervening gain of-25 dB at 63 Hz.

Claims (10)

1. Rail sleeper (8; 108), of the type comprising:

-a rigid block (9; 109) having a bottom face (34) and a top face (32) for receiving at least one longitudinal rail (4; 104);

-a casing (20; 120) for receiving said rigid block (9; 109) and in the form of a rigid shell comprising a bottom (48; 148) and a perimetric frame (50; 150) surrounding said bottom (48; 148); and

-an elastic pad (22; 122) arranged between the bottom face (34) of the rigid block (9; 109) and the bottom (48; 148) of the casing (20; 120),

the sleeper is characterized in that the dynamic stiffness k2 of the elastic tie plate (22; 122) is between 6kN/mm and 10kN/mm, preferably between 6kN/mm and 8 kN/mm.

2. Sleeper (8; 108) as claimed in claim 1, characterized in that said elastic pad (22; 122) has a substantially flat top face and a substantially flat bottom face.

3. Sleeper (8; 108) according to claim 1 or 2, characterized in that said rigid block (9; 109) has four peripheral surfaces (36, 38) connecting said top surface (32) to said bottom surface (34), said sleeper (8; 108) comprising elastic gaskets (24, 26; 124, 126) arranged between each peripheral surface (36, 38) of said rigid block (9; 109) and a peripheral frame (50; 150) of said casing (20; 120).

4. Sleeper (8; 108) according to claim 3, characterized in that said elastic pads (24, 26; 124, 126) comprise at least two elastic pads (24; 124) with a longitudinal dynamic stiffness comprised between 20kN/mm and 25kN/mm and at least two elastic pads (26; 126) with a transverse dynamic stiffness comprised between 15kN/mm and 18 kN/mm.

5. Sleeper (8; 108) according to any one of the preceding claims, characterized in that it has, on the top face (32) of the rigid block (9; 109), an elastic support element (10; 110) having a dynamic stiffness comprised between 120 and 300kN/mm, preferably between 200 and 300kN/mm, the elastic support element (10; 110) being designed to receive a rail (4; 104) resting thereon.

6. Sleeper (8) according to any one of the preceding claims, characterized in that the sleeper (8) comprises a single block (9) and a single casing (20).

7. Sleeper (8) according to claim 6, characterized in that the weight of the rigid block (9) is comprised between 350kg and 450kg, preferably between 400kg and 450 kg.

8. Sleeper (108) according to any one of claims 1 to 5, characterized in that said sleeper (108) comprises: two rigid blocks (109); two respective casings (120) associated with said rigid blocks; and a lateral spacer (184) interconnecting the two rigid blocks (109).

9. Sleeper (108) according to claim 8, characterized in that the weight of each rigid block (109) is comprised between 100kg and 150kg, preferably between 130kg and 150 kg.

10. Rail section (2; 102), characterized in that it comprises a tie (8; 108) according to any one of the preceding claims, and at least one rail (4; 104) supported on the tie (8; 108).