One-piece tie having an internal cavity

Abstract

The invention relates to a concrete railway tie, the tie comprising a central portion (12) and two rail support portions (14) positioned to either side of the central portion (12), the tie having a longitudinal axis extending from one rail support portion to the other, and the tie having at least one empty internal cavity (60) extending along the longitudinal axis in the central portion.

Description

[0001] DESCRIPTION

[0002] TITLE: MONOBLOCK CROSS BEAM WITH AN INTERNAL CAVITY

[0003] FIELD OF INVENTION

[0004] The present invention relates to a one-piece concrete railway sleeper intended to be anchored in ballast and to support railway rails. The invention also relates to a railway track comprising such a sleeper.

[0005] EARLIER ART

[0006] Railway tracks are generally formed by two rails along which trains travel. The rails are fixed to sleepers that extend perpendicularly to the rails and are anchored in a bed of ballast. The ballast is made up of a multitude of pebbles, also called ballast grains.

[0007] As trains travel on railway tracks, they generate significant vibrations and exert considerable forces on the rails, particularly lateral forces on curves. The sleepers' function is to maintain the rails parallel to each other and to keep the sleeper / rail assembly firmly anchored in the ballast in a fixed and stable position, despite the vibrations and forces exerted on the rails. For trains traveling at high speeds, the sleeper / rail assembly is subjected to even greater vibrations and forces.

[0008] Sleepers can be made from various materials, such as wood, concrete, or, more recently, polymers or composites. However, wood, polymers, and composites are not heavy and / or strong enough for use on railway lines carrying high-speed trains and / or lines with long welded rails. Because these sleepers are lightweight, they are not sufficiently anchored in the ballast to ensure good stability for the sleeper / rail assembly. Concrete sleepers, with their high density (between 2 and 2.5) and good strength, are therefore preferred, especially for railway lines carrying high-speed trains and / or lines with long welded rails.

[0009] However, the manufacture of concrete sleepers involves the consumption of natural resources such as water, gravel, sand, and the components of cement (clay and limestone), resulting in a significant carbon footprint. For example, a sleeper conforming to the standard gauge used by the SNCF (French National Railways) has a length of 2260 mm and a trapezoidal cross-section with a base of 300 mm and a height of 170 mm. Such a standard sleeper weighs 290 kg, requiring 120 liters of concrete, and the concrete material within this sleeper generates a CO₂ impact of 35 kg. The carbon footprint of such a sleeper is therefore approximately 290 g of CO₂ per liter of concrete.

[0010] DESCRIPTION OF THE INVENTION

[0011] One objective of the invention is to reduce the carbon footprint associated with the manufacture of the concrete sleeper while maintaining, or even improving, its stability in functional position, and in particular its anchoring in the ballast.

[0012] For this purpose, the invention has as its first object a concrete railway sleeper, the sleeper comprising a central portion and two rail support portions positioned on either side of the central portion, the sleeper having a longitudinal axis extending from one rail support portion to the other, the sleeper having at least one internal cavity extending along the longitudinal axis in the central portion.

[0013] Preferably, the inner cavity is empty or filled with an additional material whose density is lower than the density of the concrete forming the sleeper and / or whose carbon footprint is lower than that of the concrete forming the sleeper.

[0014] The sleeper thus contains less concrete compared to a sleeper from the previous art and can therefore be lighter and / or have a lower carbon footprint than a sleeper from the previous art.

[0015] The carbon footprint of a material corresponds in particular to the total quantity of greenhouse gases (GHG, expressed in CO₂ equivalent) emitted during its life cycle, from production to disposal. The carbon footprint values ​​mentioned in the text come primarily from data in the Environmental Product Datasheet (EPD) database, whose data is certified compliant with standard NF EN 15804 +A1 and, where applicable, version NF EN 15804 +A2.

[0016] An empty cavity means that the cavity is filled with air or a gas. When the cavity is empty, it can, according to a first embodiment, form a void within the concrete and thus be surrounded by the concrete of the sleeper, and possibly by outside air if the cavity is open to the outside of the sleeper. According to a second embodiment, the cavity can be formed by an enclosure that completely or partially surrounds the cavity, depending on whether the cavity is fully enclosed in concrete or open to the outside of the sleeper. The enclosure is then positioned between an interior space within the sleeper and the concrete of the sleeper. The enclosure can be made of any type of material capable of withstanding the pressure of the liquid concrete during the manufacture of the sleeper.The material forming the envelope can, for example, be chosen from plastic, cardboard, steel, metal, resin, a composite material, wood, concrete, cellular concrete, wood concrete, and a mixture thereof.

[0017] When the additional material has a lower density than the concrete forming the sleeper, this means that the density of the additional material is at most 2 kg / L, preferably at most 1.5 kg / L, and even more preferably at most 1 kg / L. The additional material can then be chosen, for example, from foam; porous concrete; cellular concrete; biochar-based concrete; wood; wood-based concrete; a polymer material; a mixture of industrial waste such as cardboard or plastic residues; and a mixture thereof. The weight of the sleeper is thus reduced, and the quantity of materials used to manufacture it, particularly water, cement, or sand, can be decreased. The sleeper therefore has a lower carbon footprint while maintaining stability equivalent to a prior art sleeper, since its external shape can be similar to prior art sleepers.

[0018] When the additional material has a lower carbon footprint than the concrete, this means that its carbon footprint is at most 200 g / L of additional material, preferably at most 150 g / L of additional material, and even more preferably at most 100 g / L of additional material. The additional material can then be chosen, for example, from foam; porous concrete; cellular concrete; biochar-based concrete; wood; wood-based concrete; a polymer material; a mixture of industrial waste such as cardboard or plastic residues; and a mixture thereof. The sleeper therefore has a lower carbon footprint while maintaining stability equivalent to a sleeper of the prior art, since its external shape can be similar to sleepers of the prior art.

[0019] An internal cavity is defined as a cavity formed between two lateral sides of the sleeper and not opening onto either side. In cross-section, the cavity may be closed in all radial directions and thus completely surrounded by concrete, or it may be open on an upper or lower surface of the sleeper, forming a longitudinal trench. The cavity may also be closed along one longitudinal portion and open along another.

[0020] The concrete surrounding the cavity, either completely or partially, then forms the solid part of the sleeper, and the cavity's cross-section is chosen so that there is sufficient concrete around it to ensure the sleeper is strong enough. When terms like "upper," "lower," "above," or "below" are used, they refer to a sleeper in its operational position on a ballast bed.

[0021] The longitudinal axis extends through the sleeper from one section of rail support to the other, passing through the central section. When the sleeper is in its working position on ballast, the longitudinal axis is approximately parallel to the ground.

[0022] The cross member may have a single cavity or, conversely, several cavities distributed within it. When the cross member has several cavities, it may have several cavities along the longitudinal axis and / or several cavities along radial directions. The cavities may, for example, be positioned successively along the longitudinal axis, either staggered or aligned. The cavities may also be positioned successively in a radial direction, either staggered or aligned.

[0023] The crossbeam is preferably monolithic, meaning it is manufactured in one piece and from the same material for all its parts. However, the crossbeam may include additional internal or external elements such as reinforcements or fastening devices, which are integrated during manufacturing or attached to the crossbeam after it has been manufactured.

[0024] Preferably, the concrete sleeper should have dimensions corresponding to standard sleepers so that it can be handled and put in place according to the usual procedures.

[0025] According to particular embodiments of the invention, which may be taken alone or in combination:

[0026] - in cross-section, the cavity is closed in all radial directions;

[0027] - in cross-section, the cavity is open on an upper or lower surface of the cross member;

[0028] - the cavity is elongated along the longitudinal axis; the cavity can thus have a greater or lesser length without weakening the cross member; when the cross member has several cavities, at least some, or even all, of the cavities can be elongated along the longitudinal axis;

[0029] - a section of the cavity can be, for example, round, oval, rectangular, triangular... the cavity is profiled, preferably along the longitudinal axis; the surface of the cross section is then constant along the longitudinal axis, which avoids inducing areas of weakness in the cross member;

[0030] - The cavity, or at least one of the cavities, also extends into at least one of the support sections; this allows the cavity to be lengthened and thus its volume increased without excessively widening the cavity's cross-section, so as not to weaken the sleeper; according to a possible variant, the cavity, or at least one of the cavities, extends into both rail support sections; each rail support section terminates with an end face, the cavity opening onto at least one of the end faces; thus, the cavity length is optimized; furthermore, the opening on at least one of the end faces can allow ballast grains to position themselves spontaneously within the cavity, thus contributing to the stability of the sleeper; according to a possible variant, the cavity can open onto both end faces; the cavity has a cross-section with a surface area between 1,000 mm² 2 and 10,000 mm 2including limits; the cross-sectional area of ​​the cavity can be adapted to choose the volume of the cavity and obtain the desired lightness of the sleeper; the cross-section is a first cross-section and the two rail support portions each have a second cross-section, an area of ​​the first cross-section is between 5% and 50% inclusive of the area of ​​the second cross-section; this reinforces the advantage that the cavity is surrounded by enough concrete for the sleeper to have sufficient strength; the cross-section of the sleeper is thus chosen according to the desired lightness and in such a way as to maintain a minimum strength of the sleeper;

[0031] - Each of the two rail support sections has at least one external lateral recess; this recess allows ballast grains to be accommodated when the sleeper is installed in the operating position on a bed of ballast; the sleeper is thus firmly anchored in the ballast and is therefore more stabilized than a sleeper without a recess; indeed, the ballast grains which are arranged in the recess help to hold the sleeper which thus moves less easily under the effect of passing trains; moreover, points of contact between the ballast grains and also between each ballast grain and the sleeper create frictional forces which make the movement of the sleeper even more difficult;Furthermore, the presence of a recess reduces the amount of concrete used to manufacture the sleeper, which in turn reduces the amount of water and materials used to manufacture the sleeper, and also the amount of CO₂ emitted for this manufacture;

[0032] - the recess extends over at least 80% of the length of the rail support portion; the recess thus has an optimized length allowing to accommodate more ballast grains to stabilize the sleeper; moreover, the recess thus extends even below the rail, and on both sides of the rail, when the sleeper is installed, which allows to stabilize the sleeper as close as possible to the vibrations caused by the passage of trains;

[0033] - the recess has a depth greater than or equal to 30 mm, the depth being measured in a horizontal plane; the recess thus has a depth greater than half of a possible dimension of the ballast grains which can classically range from 31.5 to 50 mm, which makes it possible to guarantee that at least some ballast grains have their center of gravity positioned in the recess and that their weight contributes to ballasting the sleeper by creating weight in the recess;

[0034] - the central portion comprises two lateral sides and anchoring elements projecting from the respective lateral sides; the anchoring elements improve the stability of the sleeper in the ballast bed, particularly due to the ballast grains which position themselves on either side of these anchoring elements when the sleeper is in a functional position;

[0035] - the central portion has at least one ballast grain receiving housing, the housing being contiguous to the anchoring element or to at least one of the anchoring elements; the housing thus makes it possible to stabilize the sleeper by receiving ballast grains without adding weight to the sleeper; preferably the housing does not have a bottom face;

[0036] - the housing is delimited by two of the anchoring elements or by the anchoring element and one of the support portions; the ballast grains are thus retained in the housing; when the housing is delimited by two anchoring elements, they extend over the same width;

[0037] - the width of the central portion is less than the width of the rail support portions; the rail portions thus protrude from the central portion, preferably by a width equivalent to the width of the anchoring elements;

[0038] - the anchoring element(s) extend from one of the lateral sides over a width greater than or equal to 30 mm; this width ensures that the ballast grains have at least half of their dimension inside the housing; and

[0039] - the anchoring element(s) extend over at least 80% of the height of the sleeper; the housing is thus formed over at least 80% of this height, which allows several grains of ballast to be stacked according to the height.

[0040] The invention has as its second object a railway track comprising at least one sleeper according to the first object.

[0041] The railway track is thus more stable than a railway track consisting solely of sleepers according to the prior art. Preferably, the railway track comprises a plurality of sleepers such as those previously described, and even more preferably, only sleepers such as those previously described.

[0042] The third object of the invention is the use of a previously described sleeper in which the sleeper is installed on a railway track leaving the cavity empty.

[0043] The cavity is therefore not used for any purpose other than to lighten the crossbeam. At most, when the cavity opens onto one or both end faces, a few grains of ballast may enter one or both of the opening ends of the cavity.

[0044] However, the introduction of the ballast grains is spontaneous and unavoidable in this case and does not result from operator intervention. Furthermore, the majority of the cavity remains empty.

[0045] BRIEF DESCRIPTION OF THE FIGURES

[0046] Other features and advantages of the invention will become apparent from the following description, given solely by way of example and with reference to the accompanying drawings, in which:

[0047] - Figure 1a represents a schematic and perspective view of a cross member according to a first embodiment of the invention;

[0048] - Figure 1b represents a perspective and cross-sectional view of the cross member of Figure 1a;

[0049] - Figure 1c represents a schematic top view of the cross member in Figure 1a;

[0050] - Figure 1d represents a schematic side view of the cross member in Figure 1a;

[0051] - Figure 2a represents a schematic top view of a cross member according to a variant of the first embodiment of the invention;

[0052] - Figure 2b represents a schematic and perspective view of the crossbeam in Figure 2a;

[0053] - Figure 2c represents a schematic and cross-sectional view of a variant of the cross member of Figure 2a;

[0054] - Figure 3a represents a schematic perspective view of a cross member according to a second embodiment of the invention;

[0055] - Figure 3b shows a schematic top view of the cross member in Figure 3a; - Figure 3c shows a schematic side view of the cross member in Figure

[0056] 3a; and

[0057] - Figure 4 schematically represents, in top view, a railway track according to one embodiment of the invention.

[0058] DETAILED DESCRIPTION OF A PROJECT EXAMPLE

[0059] With reference to figures 1a to 1d, a railway sleeper 10A according to a first embodiment of the invention comprises a central portion 12 and two rail support portions 14 (or support portions) positioned on either side of the central portion 12. The support portions 14 are more particularly positioned at each end of the sleeper 10. The sleeper 10A has a longitudinal axis extending from one support portion 14 to the other.

[0060] The crossbeam 10A has an internal cavity 60, visible in Figure 1b, extending along the longitudinal axis (X). In this embodiment, this cavity is empty. The cavity 60 forms a hollow part of the crossbeam 10A, and the concrete surrounding the cavity forms a solid part 62 of the crossbeam.

[0061] However, the description also applies to a cavity filled with additional material having a lower density than the concrete surrounding the cavity and / or having a lower carbon footprint than the concrete surrounding the cavity.

[0062] In this embodiment, the internal cavity is described as "closed" because, in cross-section and longitudinal section, it is completely surrounded by concrete. However, according to a possible variant, the internal cavity could be open on an upper or lower surface of the crossbeam, or on one of its two ends. The cavity is also described as "closed" when the additional material is completely surrounded by concrete, and "open" when the additional material is in contact with the outside of the crossbeam.

[0063] The sleeper 10A is, in this case, a single-piece concrete unit with an elongated shape and an overall square cross-section. The density of the solid part 62 of the sleeper is, in this example, at least 1.8, preferably at least 2, and for example 2.4. In this way, the sleeper is sufficiently heavy and stable when in its working position and can therefore be used for railway tracks on which high-speed trains run.

[0064] The central portion 12 preferably has a width L2 less than a width L3 of the rail support portions 14, the width being measured in a horizontal direction and perpendicular to the longitudinal axis X. The separation between each support portion 14 and the central portion 12 is made in a narrowing zone 13, the central portion 12 corresponding to the whole part of the sleeper which is located between the support portions 14 and which has a width L2.

[0065] The reduced width of the central section 12 compared to the rail support sections 14 allows the sleeper 10A to be lighter than a sleeper with a width equal to that of the rail support sections along its entire length, while still being sufficiently anchored in the ballast. This sleeper shape thus reduces the amount of concrete used in its manufacture, thereby also limiting the amount of water and materials used, and the amount of CO₂ emitted during its production.

[0066] Cavity 60 is elongated along its longitudinal axis, allowing the void space to be distributed along the length of the sleeper. The length of the cavity can be adjusted to the desired void volume inside the sleeper. Specifically, the void volume is chosen to strike a balance between a weight sufficiently reduced to limit the amount of material used in the sleeper's manufacture and a weight sufficient to ensure the sleeper's stability on the ballast bed.

[0067] In this embodiment, the cavity 60 has a round and closed cross-section, as illustrated in particular in figure 1b, but the section can have other shapes and be for example oval, square or rectangular, and possibly open on the upper or lower surface of the cross-section.

[0068] The cavity 60 is profiled and thus has a constant cross-section along its entire length. Preferably, the cavity 60 is concentric with the longitudinal axis X so that the amount of concrete surrounding the cavity 60 is uniform along its entire length. Therefore, the crossbeam does not have any weak points where the amount of concrete surrounding the cavity could be insufficient.

[0069] The invention is not limited to a single cavity, and the cross member may comprise several cavities. The cavities may then be aligned along the longitudinal axis and / or in radial directions. When the cross member has several cavities, they may all be open, all closed, or some cavities may be open and some may be closed.

[0070] The cavity 60, or cavities if the sleeper has several, can also extend into at least one of the support sections 14, as shown in Figure 2a, or even into both rail support sections 14. The range of possible cavity lengths is therefore large, allowing for a wide choice of void volumes within the sleeper. When a sleeper of standard length 2260 mm has a single cavity, this cavity can have a length between 1000 mm and 2260 mm inclusive. Generally, the length of a cavity, or the sum of the lengths of several cavities aligned along the longitudinal axis, can be between 20% and 100% inclusive of a maximum length Im of the sleeper.

[0071] Each rail support section 14 terminates in an end face 15 that extends substantially perpendicularly to the longitudinal axis. According to an alternative embodiment shown in Figures 2a and 2b, the cavity 60 can then open onto at least one of the end faces 15. When the sleeper 10A has several cavities aligned along the longitudinal axis, at least one of the sleeper's cavities can then open onto at least one of the end faces 15. The cavity, or one of the cavities, thus forms an opening 63 on the end face. This opening 63 allows ballast grains to naturally position themselves in the cavity 60 without operator intervention, thereby helping to stabilize the sleeper 10A when it is in its operating position.

[0072] According to another possible embodiment, the cavity 60 can also open onto each of the end faces 15 and thus be through-hole. When the cross member 10A has several cavities aligned along the longitudinal axis, one of the cavities can open onto one end face 15 and another cavity can open onto the other end face 15.

[0073] Cavity 60 has a first cross-section which can have a surface area of ​​between 1000 mm 2 and 10,000 mm 2 terminals included. Such a cross-section ensures that the volume of the solid part 62 of the cross member 10A, which totally or partially surrounds the cavity 60, is sufficiently large to maintain the cross member's strength. The cavity volume can thus be chosen by determining the cavity length and the first cross-section, in order to achieve a compromise between reducing the cross member's weight and maintaining its strength.

[0074] When the cross member has several cavities in a radial direction, the sum of the areas of the first cross-section of the different cavities can be between 1,000 mm 2 and 10,000 mm 2 terminals included.

[0075] The solid part of the cross member 10A totally or partially surrounding the cavity 60 or cavities is then sufficiently thick to ensure the strength of the cross member.

[0076] In this case, the support portions 14 have a second cross-section, and the area of ​​the first cross-section can be between 5% and 50% (inclusive) of the area of ​​the second cross-section. The second cross-section corresponds to the entire cross-section, which therefore includes the solid part and the first cross-section. Furthermore, the central portion 12 has a third cross-section, and the area of ​​the first cross-section can be between 5% and 50% (inclusive) of the area of ​​the third cross-section. The third cross-section corresponds to the entire cross-section, which therefore includes the solid part and the first cross-section.

[0077] In addition, the sleeper 10A has two fastening devices 28 onto which iron rails can be conventionally fixed. In particular, one fastening device is positioned on the upper surface 26 of each rail support section 14.

[0078] The sleeper 10A is designed to be anchored conventionally in a ballast bed. When the sleeper 10A is in its working position in the ballast, it rests on ballast grains and its lateral faces are surrounded by ballast grains. In this position, the upper surface 26 of the sleeper 10A emerges from the ballast grains.

[0079] According to an alternative embodiment shown in the cross-section of the cross member 10A illustrated in Figure 2c, the cavity 60 can be opened on the upper face 26 of the cross member.

[0080] According to this embodiment, where the sleeper extends into one or both rail support sections, the cavity is interrupted or closed beneath the rail to prevent weakening the sleeper in the section most subjected to the weight of trains and the vibrations caused by their passage. Specifically, the cavity is interrupted at least between the two fastening devices 28, and preferably over a portion extending from 20% to 80% of the length of the rail support section(s) 14, this portion including the two fastening devices 28.

[0081] When the internal cavity 60 is open on the upper surface 26 of the crossbeam, it may include openings leading to one or both end faces, one or both lateral sides, and / or the lower surface of the crossbeam. The cavity then has a bottom with sloping portions leading down to the openings. These openings are designed to drain any water that may be present in the internal cavity, particularly rainwater.

[0082] In the embodiment illustrated in Figures 1a-d and 2a-c, the sleeper 10A has two external lateral recesses 16a, b on the sides of each support section 14. Each recess accommodates ballast grains when the sleeper is installed in its operating position on a ballast bed. The presence of ballast grains in the external lateral recesses 16a, b adds weight to each recess, thus increasing the weight of the support sections 14. The recesses 16a, b, which hold the ballast grains, therefore increase the anchorage of the sleeper 10A in the ballast, particularly the anchorage of the section of the sleeper most likely to move during train passage. Ballasting the sleeper with ballast grains at this support section 14 thus optimizes the stability of the sleeper 10A in the ballast.

[0083] In addition, points of contact between the ballast grains and also between each ballast grain and the sleeper 10A create frictional forces which limit, or even prevent, any movement of the sleeper.

[0084] Each recess 16a, b is formed by a lateral flank 18a, b of the support portion 14 as well as by three faces 20a, b, 22a, b and 24a, b projecting from the lateral flank 18a, b.

[0085] Advantageously, the recess 16a, b is positioned at the level of the support portion 14 because it is the portion of the sleeper 10A on which the railway rails rest when the latter is in its position of use, and therefore the portion of the sleeper 10A which particularly needs to be stabilized.

[0086] Face 20a of the recess forms a bottom face, face 22a is an outer lateral face, and face 24a is an inner lateral face. In this embodiment, the three faces 20a, 22a, and 24a extend laterally over a distance L1 greater than or equal to 30 mm. Thus, the recess has a height and depth substantially equal to or greater than the largest dimension of a ballast grain. In this way, at least some ballast grains have the majority of their volume within the recess, and the weight of each ballast grain contributes to the weighting of the sleeper by exerting pressure on the bottom face 20a. The depth L1 corresponds to the distance between the lateral flank 18a of the support portion 14 and a free edge 17a of the bottom face 20a.

[0087] Furthermore, the recess 16a has an average height He defined as the average vertical distance between the upper surface 26 of the cross member and an upper surface of the free edge 17a of the bottom face 20a. The height He is also greater than or equal to 30 mm, and preferably between 120 and 200 mm inclusive.

[0088] The bottom face 20a, particularly its upper surface, forms an angle of 120° with the side 18a. Advantageously, the inclination of the bottom face 20a is a compromise between an inclination shallow enough to allow the ballast grains to remain in place within the recess 18a and an inclination sufficient to reinforce the bottom face 20a and prevent it from breaking under the impact of the ballast grains or during handling. Furthermore, the inclination of the bottom face 20a allows it to be thicker in the portion positioned against the side 18a than at its free edge 17a, thus increasing its strength. According to possible embodiment variants, the inclination of the bottom face 20a can have a value between 95° and 150° inclusive, preferably between 100° and 135° inclusive, with respect to a vertical plane.

[0089] Each rail support section 14a has a length 11, and the bottom face, specifically the free edge 17a, b of the bottom face 20a, extends over a length 12 at least equal to 80% of the length 11. The length of the recess 16a, b is thus optimized to increase the weight of the sleeper over a large portion of the rail support section 14a, which is the section most prone to movement due to train traffic. In particular, the recess 16a, b even extends under the rail when the sleeper is in its operational position to form a railway track.

[0090] In this embodiment, the central portion 12 has two lateral sides 32a and 32b which are flat.

[0091] We will now present a second embodiment. Only the characteristics differing from those of the first embodiment will be described.

[0092] In the second embodiment shown in Figures 3a, 3b, and 3c, a sleeper 10B differs from the sleeper 10A in that it has two anchoring elements 40a, b that project from the lateral sides 32a, b of the central portion in a transverse direction. When the sleeper 10B is in its operating position on the ballast grains, ballast grains are arranged on either side of the anchoring elements 40a, b, thereby improving the stability of the sleeper.

[0093] The central portion 12 then has a width L2 which is measured between the anchoring elements 40a, b and which corresponds to the distance separating the two lateral sides 32a and 32b.

[0094] Sometimes, in the continuation of the description of this second embodiment, only the elements of one of the lateral faces of the cross member 10A will be described (elements indexed "a") but the description also applies to the other lateral face which is identical (elements indexed "b").

[0095] The two anchoring elements 40a allow three housings to be formed along the face of the lateral side 32a and 32b. A first housing 44a is formed between the two anchoring elements 40a and two housings 42a are formed between each anchoring element 40a and the support portion 14 which is juxtaposed to them.

[0096] In the case where the sleeper 10B has a single anchoring element 40a, two recesses are formed between the anchoring element 40a and each of the adjacent support sections 14. The recesses 42a, b and 44a, b formed along each lateral side 32a, b accommodate ballast grains and thus further improve the stability of the sleeper 10B when in use. Indeed, the points of contact between the ballast grains, and also between each ballast grain and the sleeper, create frictional forces that make it more difficult for the sleeper 10B to move when trains pass over it.

[0097] In this embodiment, a distance D2 between two anchoring elements 40a, b is greater than the distance D1 between an anchoring element and the inner face 24a. However, the anchoring elements can be distributed differently.

[0098] The sleeper 10B has an average height H that ranges from a maximum height Hm at the end of the sleeper to a minimum height in the middle of the sleeper, the minimum height being slightly less than the maximum height. The anchoring elements 40a, b extend over at least 80% of the height H of the sleeper 10A, the height being measured at the location of each anchoring element 40a, b. In this way, the contact surface between the anchoring elements 40a, b and the ballast grains positioned in the recesses 42a, b and 44a, b is optimized.

[0099] The anchoring elements 40a, b have a triangular shape in top view and extend over at least 80% of the height of the cross member 10B. However, the anchoring elements may have other shapes and be for example square, rectangular or semi-circular in section.

[0100] Furthermore, the anchoring elements 40a protrude from the lateral side 32a by a distance L4 which is greater than or equal to 30 mm. The housings 42a and 44a thus have a lateral depth sufficient to accommodate at least half the volume of the ballast grains so that the latter contribute to stabilizing the sleeper.

[0101] The cross member 10B is symmetrical on both sides of the longitudinal axis X. Thus, each anchoring element 40a of the first lateral flank 32a is aligned with an anchoring element 40b of the second lateral flank 32b. In other words, the anchoring elements of the two lateral flanks 32a, b are aligned in pairs. The cross member 10B is therefore stabilized identically on each of its lateral flanks 32a, b.

[0102] According to another possible embodiment not shown, the sleeper may have one or more anchoring elements on each lateral side of the central portion and may not have recesses in the rail support portions.

[0103] With reference to Figure 4, a railway track 50 according to one embodiment of the invention comprises a plurality of sleepers 10 as described according to the first or second embodiment and two rails 52 fixed to the fastening devices 28 of each of the sleepers 10.

[0104] The cavity characteristics described above apply to the sleepers of both embodiments described. The railway track is thus more stable than a railway track consisting solely of sleepers according to the prior art and allows for high-speed train operation.

[0105] During use, sleeper A or B is placed on the ballast bed and partially embedded in it, then the rails are fixed to the support sections. The cavity is then left empty.

[0106] When the cavity opens onto one or both end faces, ballast grains may occupy the opening end of the cavity, but the cavity is not intended to accommodate other elements.

Claims

DEMANDS 1. Railway sleeper (10A, 10B) made of concrete, the sleeper comprising a central portion (12) and two rail support portions (14) positioned on either side of the central portion (12), the sleeper having a longitudinal axis extending from one rail support portion to the other, the sleeper (1 OA, 10B) having at least one internal cavity (60) extending along the longitudinal axis (X) in the central portion (12).

2. Railway sleeper (10A, 10B) according to claim 1, wherein the cavity is filled with an additional material whose density is lower than the density of the concrete forming the sleeper and / or whose carbon footprint is lower than that of the concrete forming the sleeper.

3. Railway sleeper (1 OA, 10B) according to claim 1 or 2, wherein the inner cavity is empty.

4. Railway sleeper (1 OA, 10B) according to claim 1 to 3, in which, in cross-section, the cavity (60) is closed in all radial directions.

5. Railway sleeper (1 OA, 10B) according to claim 1 to 3, wherein, in cross-section, the cavity (60) is open on an upper (26) or lower surface of the sleeper (10A, 10B).

6. Cross member (10A, 10B) according to any one of the preceding claims, wherein the cavity (60) is elongated along the longitudinal axis (X).

7. Cross member (10A, 10B) according to any one of the preceding claims, wherein the cavity (60) or at least one of the cavities (60) also extends into at least one of the rail support portions (14).

8. Cross member (10A, 10B) according to any one of the preceding claims, wherein each rail support portion (14) terminates with an end face (15), the cavity (60) opening onto at least one of the end faces (15).

9. Cross member (10A, 10B) according to any one of the preceding claims, wherein the cavity (60) has a cross-section having a surface area between 1000 mm 2 and 10,000 mm 2 terminals included.

10. Cross member (1 OA, 10B) according to the preceding claim, the cross section being a first cross section, the two rail support portions (14) each have a second cross section, an area of ​​the first cross section is between 5% and 50% inclusive of the area of ​​the second cross section.

11. Cross member (10A, 10B) according to any one of the preceding claims, wherein each of the two rail support portions (14) has at least one external lateral recess (16a, b).

12. Cross member (10A, 10B) according to the preceding claim, wherein the recess (16a, b) extends over at least 80% of a length (11) of the rail support portion (14).

13. Cross member (10A, 10B) according to claim 11 or 12, wherein the recess (16a, b) has a depth greater than or equal to 30 mm, the depth being measured in a horizontal plane.

14. Cross member (10A, 10B) according to any one of the preceding claims, wherein the central portion (12) comprises two lateral flanks (32a, b) and anchoring elements (40a, b) projecting from the respective lateral flanks (32a, b).

15. Crossbeam (10A, 10B) according to claim 14, wherein the central portion (12) has at least one ballast grain receiving housing, the housing being contiguous to the anchoring element (40a, b) or to at least one of the anchoring elements (40a, b).

16. Cross member (10A, 10B) according to claim 15, wherein the housing is delimited by two of the anchoring elements (40a, b) or by the anchoring element (40a, b) and one of the support portions (14).

17. Cross member (10A, 10B) according to any one of claims 14 to 16, wherein the anchoring element or each anchoring element (40a, b) extends from one of the lateral sides (32a, b) over a width (L4) greater than or equal to 30 mm.

18. Cross member (10A, 10B) according to any one of claims 14 to 17, wherein the anchoring element or each anchoring element (40a, b) extends over at least 80% of a height H of the cross member (10A).

19. Railway track comprising at least one sleeper (10A, 10B) according to any one of claims 1 to 18.

20. Use of the sleeper (1 OA, 10B) according to any one of claims 1 to 18, wherein the sleeper (1 OA, 10B) is installed on a railway track leaving the cavity empty.

Images