METHOD AND STRIP FOR ALIGNING A SOUNDPROOF RAILWAY

Abstract: The invention concerns a method for laying a railway with rails (3) which rest on a support (4) over practically their entire length, whereby a vibration-isolating strip (1), containing at least a first and a second layer (7, 8) lying on top of one another and having a different rigidity, is provided between the rails (3) and the support (4), and whereby, when the rails (3) are laid and/or aligned, mainly said first layer (7), having the lowest rigidity, is compressed until its rigidity is of at least the same order of magnitude as that of said second layer (8).

Description: METHOD AND STRIP FOR ALIGNING A SOUNDPROOF RAILWAY The invention concerns a method and a vibration-isolating strip for laying a railway with rails which rest on a support over almost their entire length, whereby the strip, containing at least a first layer and a second layer with a different rigidity, situated on top of one another, is provided between the rails and the support. According to the state of the art, a strip is used consisting of a first layer with a low rigidity for the isolation of the vibrations, whereas a second layer mainly functions as a protective layer for the first layer. Such strips are described for example in EP-A-0 726 359 and US-A-5 011 077. In order to obtain a railway whereby as little sound or vibrations as possible are transferred to the environment via the rails, it is important that the upper surface of the rails is made almost entirely fiat, whereby the rigidity of the rail is almost constant over its entire length. According to the methods applied until now, or by means of the known vibration-isolating strips, it is not possible, however, to lay a railway with an almost perfectly flat upper surface in a simple manner. The vertical tolerances which are reached up to now are in the order of magnitude of 3 mm. By perfectly aligning the upper surface of the rails of a railway, we can moreover reduce the wear of the rails. The differences in height which may occur in the upper surface of the rails are among others due to tolerances in the height of the rails themselves, the bearing capacity of the base and the thickness of the support of the rails. The invention aims to remedy these disadvantages by introducing a method and a vibration-isolating strip which make it possible to lay a railway in a simple manner whereby the upper surface of the rails is very precisely aligned. Moreover, the method and the strip according to the invention offer an additional advantage in that rails can be easily replaced by new rails which are very precisely aligned, without the necessity of breaking away the support for the rails. To this aim, when the rails are laid and/or aligned, mainly said first layer, having the lowest rigidity, is compressed until its rigidity is at least of the same order of magnitude as that of said second layer. Practically, the first layer is compressed until its thickness amounts to 25 to 50%, and in particular 30 to 40%, of its original thickness. According to a special embodiment of the method according to the invention, a material is selected for said first layer whose rigidity is at least five times smaller than the rigidity of said second layer. According to a specific embodiment of the method according to the invention, a material is selected for said first layer having a rigidity between 10 and 25 MN/rn 3 , and which amounts in particular to almost 20 MN/m 3. According to a preferred embodiment of the method according to the invention, a material is selected for said second layer with a rigidity between 3 3 50 and 150 MN/m , and which amounts in particular to almost 110 MN/m . The strip according to the invention has at least a first layer and a second layer situated on top of one another whereby, when not compressed, the rigidity of said first layer is smaller than that of said second layer. This strip can be compressed between the rails of a railway and the support for these rails, whereby, in the compressed strip, the rigidity of said first layer is at least of the same order of magnitude as that of the second layer. According to a preferred embodiment of the strip according to the invention, said first layer mainly consists of a material having a rigidity which is at least five times smaller than the rigidity of said second layer. According to a special embodiment of the strip according to the invention, said first layer mainly consists of a material with a rigidity situated between 10 and 25 MN/m , and which amounts in particular to almost 20 MN/m 3 . Preferably, said second layer mainly consists of a vibration- 3 isolating material with a rigidity situated between 50 and 150 MN/m , and which amounts in particular to almost 110 MN/m . Other particularities and advantages of the invention will become clear from the following description of a few special embodiments of the invention; this description is given as an example only and does not restrict the scope of the claimed protection in any way; the reference figures used hereafter refer to the accompanying drawing. This figure is a schematic cross section of a rail from a railway with a strip according to the invention. For clarity's sake, the part of the figure to the left of line I-I represents a situation in which the rail rests on the strip when it is not compressed, whereas the part of the figure to the right of line I-I represents the strip when it is compressed. The same reference figures refer to identical or analogous elements. The strip according to the invention is mainly used for laying a continuously supported track. These are rail systems whereby the rails rest on a support over their entire length. Such a continuous support may for example consists of a concrete base or of connecting sleepers placed next to one another. The strip 1 according to the invention, as represented in the figure, has almost the same width as the foot 2 of a rail 3 and is provided between this foot 2 and the support 4 of the rail 3. Further, the rail 3 is fixed to the support 4 via the foot 2 by means of mounting clips 5 and 6 known as such. The strip 1 represented in the figure consists of two layers 7 and 8 situated on top of one another. A first layer consists of an adjusting layer 7 made of a very flexible material which, as will be further described, is considerably compressed as the rail 3 is aligned. The second layer forms a damping layer 8 which makes sure that vibrations of the rail 3 are damped and that the transfer of vibrations to the support 4 is strongly reduced. The adjusting layer 7 has what is called a static bed module which, when not compressed, is smaller than that of the damping layer 8. For the sake of convenience, the quantity static bed module will be referred to in short by the term rigidity. For the adjusting layer 7 is preferably selected a material with a rigidity which is at least five times smaller than the rigidity of the damping layer 8. Thus, the rigidity of the adjusting layer 7 amounts to for example 20 MN/m , whereas the rigidity of the damping layer amounts to for example 110 MN/m . In general, a material is preferably selected for the adjusting layer 7 with a rigidity situated between 10 and 25 MN/m , and a material is used for the damping layer 8 having a rigidity which is preferably situated between 50 and 300 MN/m 3 , in particular between 50 and 150 MN/m 3 . When a railway is laid according to the method of the invention, the rail 3 will be aligned during or after the positioning of the latter on the strip 1. This implies that the mounting clips 5 and 6 are tightened via bolts, which are not represented in the figure, so as to firmly connect the rail 3 to the support 4, whereby, near the corresponding mounting clips 5 and 6, a specific vertical movement is imposed on the rail 3 so as to make the upper surface 9 of the rail 3 completely flat over its entire length. By thus providing a clamping force on the mounting clips, the adjusting layer 7 is compressed until its rigidity amounts to at least the same order of magnitude as that of said damping layer 8. The compressed layer 7 is preferably more rigid than the damping layer 8. The compression of the adjusting layer 7 makes sure that possible vertical deviations of the support 4 or of the thickness of the rails 3 are compensated for by a corresponding compression of the adjusting layer 7. In particular, the adjusting layer 7 is compressed to a thickness which amounts to 25 to 50%, and in particular to 30 to 40% of its original thickness. In the figure, the strip 1 is represented in a non-compressed condition to the left of line I-I. The mounting clip 5 is situated in a corresponding position and is sufficiently tightened to connect the rail 3 to the support 4 in a provisional manner. To the right of line I-I, the strip 1 is represented as compressed. The mounting clip 6 is hereby tightened such that the rail 3 is firmly connected to the support 4, whereas the upper surface of the rail 3 is aligned. As can be clearly derived from this figure, the adjusting layer 7 is compressed to almost 40% of its original thickness, whereas the damping layer 8 is subjected to a relatively small compression. In order to make the isolation of the rail 3 in relation to the support 4 optimal, a connecting piece which is not represented in the figure is provided between the mounting clips 5 and 6 and the foot 2, forming an acoustic partition. This connecting piece is made for example of a cork/rubber elastomer which is internally reinforced with synthetic fibres known under the brand name "Kevlar". In a particularly interesting embodiment of the method and the strip according to the invention, the adjusting layer 7 consists of a microcellular rubber having a rigidity of 20 MN/m , whereas, for the damping layer 8, an elastomer known as such is used having a rigidity of 110 MN/m . The thiclcness of the damping layer 8 amounts for example to 12 mm, whereas that of the adjusting layer 7 in a non-compressed condition amounts to 10 mm. When the rails 3 are laid, the adjusting layer 7 is compressed to almost 4 mm. When the rails 3 have to be replaced due to wear, one only has to remove them from the support 4 and mount new rails 3 instead without breaking away the support 4. It is sufficient to mount the new rails again by means of the strip 1, according to the invention, and to align them by tightening the mounting clips 5 and 6, such that a suitable compression of the adjusting layer 7 is obtained. Naturally, the invention is not restricted to the above-described method and strip according to the invention. Thus, the strip according to the invention may consist for example of more than two layers lying on top of one another, which may either or not all have a different rigidity, or it may have standing edges which enclose the foot of the rail at least partially. Of course, the width of the strip is not necessarily equal to the width of the rails. The different layers of a strip according to the invention may also continuously merge into one another, such that a strip is obtained which has a varying rigidity fluctuation according to a vertical direction. Further, contrary to what is represented in the figure, the adjusting layer may also form the top layer of a strip.

Claims: 8 v» i t μ «, w ' / V u y y ^ CLAIMS 1. Method for laying a railway with rails (3) which rest on a support (4) over practically their entire length, whereby a vibration-isolating strip (1), containing at least a first and a second layer (7,8) lying on top of one another and having a different rigidity, is provided between the rails (3) and the support (4), characterised in that, when the rails (3) are laid and/or aligned, mainly said first layer (7), having the lowest rigidity, is compressed until its rigidity is of at least the same order of magnitude as that of said second layer (8). 2. Method according to claim 1, characterised in that said first layer (7) is compressed until its thickness amounts to 25 to 50%, and in particular 30 to 40%, of its original thickness. 3. Method according to claim 1 or 2, characterised in that microcellular rubber is used for said first layer (7). 4. Method according to any of claims 1 to 3, characterised in that an elastomer is used for said second layer (8). 5. Method according to any of claims 1 to 4, characterised in that a material is selected for said first layer (7) having a rigidity which is at least five times smaller than the rigidity of said second layer (8). 6. Method according to any of claims 1 to 5, characterised in that a material is selected for said first layer (7) having a rigidity which is situated between 10 and 25 MN/m , and which amounts in particular to almost 20 MN/m 3 . 7. Method according to any of claims 1 to 6, characterised in that a material is selected for said second layer (8) having a rigidity which is situated between 50 and 150 MN/m 3 , and which amounts in particular to almost 110 MN/m 3 . 8. Strip, in particular to be applied in the method according to any of the preceding claims, having at least a first layer (7) and a second layer (8) situated on top of one another, whereby the rigidity of said first layer (7), when not compressed, is smaller than that of said second layer (8), characterised in that the strip (1) can be compressed between the rails (3) and the support (4) for the rails (3), whereby, in the compressed strip (1), the rigidity of said first layer (7) is at least of the same order of magnitude as that of the second layer (8). 9. Strip according to claim 8, characterised in that said first layer (7) has a material with a rigidity which is at least five times smaller than the rigidity of said second layer (8). 10. Strip according to claim 8 or 9, characterised in that said first layer (7) mainly consists of a material with a rigidity situated between 10 and 25 MN/m , and which in particular amounts to almost 20 MN/m . 11. Strip according to any of claims 8 to 10, characterised in that said second layer (8) mainly consists of a vibration-isolating material with a 3 rigidity situated between 50 and 150 MN/m , and which amounts in particular to almost 110 MN/m 3 . 12. Strip according to any of claims 8 to 11, characterised in that said first layer (7) is at least partially made of microcellular rubber. 13. Strip according to any of claims 8 to 12, characterised in that said second layer (8) is at least partially made of an elastomer. 14. Strip according to any of claims 8 to 13, characterised in that said first layer (7), when it is not compressed, has a thickness between 10 mm and 25 mm.

Inventors: CARELS PATRICK, CARELS, PATRICK
Applicants: CARELS PATRICK, COMPOSITE DAMPING MATERIAL NV, CARELS, PATRICK, COMPOSITE DAMPING MATERIAL N.V., IN HET KORT "CDM"
Application year: 2001
Main classification: E01B9
IPC codes: E01B9, E01B19