EP3591119A1

EP3591119A1 - Method and system for the rehabilitation of the base of a railway line

Info

Publication number: EP3591119A1
Application number: EP19183796.2A
Authority: EP
Inventors: Alberto Majer; Roi Bernard
Original assignee: Ivecos SpA
Current assignee: Ivecos SpA
Priority date: 2018-07-03
Filing date: 2019-07-02
Publication date: 2020-01-08
Anticipated expiration: 2039-07-02
Also published as: SI3591119T1; IT201800006890A1; EP3591119B1

Abstract

A method for the rehabilitation of the base of a railway line (1) having a horizontal layer (6) of compact material positioned below the tracks (4), the method comprising a step of removing, on both sides of the tracks (4), a continuous longitudinal portion (6a) of the horizontal layer (6) to form a relative continuous longitudinal cavity (11), a step of injecting a resinous material in a fluid form in the longitudinal cavity (11), the resinous material being such as to reconstitute, after hardening, the continuity of the horizontal layer (6) of compact material.

Description

This invention relates to a method for the rehabilitation of the base of a railway line.
In particular, the invention relates to a method for the rehabilitation of the base of a railway line having a horizontal layer of compact material positioned below the tracks.
In the past, most of the railway lines were made by placing a stone ballast on the one on which the sleepers designed to support the actual tracks were positioned.
As an alternative to this long-established technique, in some circumstances with difficult construction and costly and complex maintenance, in tunnels and on viaducts, a reinforced concrete base foundation has been used on which are positioned in succession pre-compressed reinforced concrete platforms, designed to directly support the tracks.
This type of construction is used, for example, in some tunnels with a length of more than 2000 metres on European railway lines in which, also with the aim of making the tunnel suitable for use by vehicles with rubber tyres, such as rescue vehicles, the stone ballast has been eliminated.
A compact solid layer, advantageously made of bituminous mortar, is normally interposed between the base foundation and the pre-compressed reinforced concrete platforms is normally interposed, designed to support and regularise the contact between the two above-mentioned components, as well as absorbing the stresses of the railway loads. Unfortunately, due to the presence of very aggressive water circulating along the tracks, in general due to the infiltrations always present in the tunnels, this layer of bituminous mortar is exposed to a deterioration which is sometimes even rapid.
The consequence of the deterioration of the bituminous mortar layer is an instability on the railway structure, with generation, with the transit of the railway trains, of harmful vibrations which in the long term can cause dangerous failures.
At present, the only known method for overcoming the problem of the deterioration of the bituminous mortar layer consists in removing it after removal of the railway tracks and the removal of the pre-compressed reinforced concrete platforms which overly the layer of bituminous mortar. This operation, as well as being particularly onerous in operational terms, is sometimes difficult to perform on account of the long railway traffic stoppage which it requires.
The technical times necessary for all the above-mentioned operational steps, as well as the necessary re-positioning of the parts removed, is not in fact compatible with the required operations for normal railway lines. The aim of this invention is to overcome the drawbacks of the prior art by means of a method for rehabilitation of the base of the railway line which allows the effectiveness of the compact solid layer interposed between the base foundation and the pre-compressed reinforced concrete platforms to be restored.
A further aim of the invention is to provide a method for rehabilitating the base of the railway line which is able to limit the necessary intervention times.
Another aim of the invention is to provide a method for rehabilitating the base of the railway line which allows the operations to be performed at the site to be simplified.
The technical features of the invention, with reference to the above aims, can be easily inferred from the appended claims, in particular claim 1, and preferably any of the claims that depend, either directly or indirectly, on claim 1.
The advantages of the invention are more apparent from the detailed description which follows, with reference to the accompanying drawings which illustrate a preferred, non-limiting example embodiment of the invention and in which:

Figure 1 is a schematic perspective view, with some parts transparent and others cut away for simplicity, of a step of the method for the rehabilitation of the base of a railway line according to the invention;
Figures 2 and 3 are schematic perspective views of a portion of railway line during two different operating steps of the method according to the invention;
Figure 4 is a schematic cross-section of the railway line during a further step of the method according to the invention;
Figure 5 is a schematic side elevation view of a component of the system used for implementing the method according to the invention.

As illustrated in Figure 1, the reference numeral 1 denotes in its entirety a railway line of the type comprising a base foundation 2 made of reinforced concrete and a plurality of pre-compressed reinforced concrete platforms 3, positioned in succession on the base foundation 2.
The railway line 1 also comprises tracks 4 which are fixed to the above-mentioned platforms 3 by means of respective clips 5 of known type.
The tracks 4 extend longitudinally along a first predetermined direction D1. A horizontal layer 6 of compact material is interposed between the base foundation 2 and the pre-compressed reinforced concrete platforms 3. The above-mentioned horizontal layer 6 of compact material has a thickness of several centimetres.
The material with which the horizontal layer 6 is made is normally a bituminous mortar.
The method according to the invention comprises the removal, on both sides of the tracks 4, of a continuous longitudinal portion 6a of the horizontal layer 6 of compact material.
Figure 1 shows an apparatus 7 designed for the removal of the continuous longitudinal portion 6a of the horizontal layer 6 of compact material and comprising a carriage 8 slidable along the tracks 4 of the railway line 1, an operating head 9 for removing the compact material of the above-mentioned horizontal layer 6, the operating head 9 having a blade 10 having a substantially flat extension.
The apparatus 7 designed for removing the above-mentioned continuous longitudinal portion 6a forms the object of a parallel patent application in the name of the same Applicant to which reference should be made for completeness and it will not therefore be described in detail herein.
The method according to the invention relates to the rehabilitation of the base of a railway line 1 having a horizontal layer 6 of compact material positioned below the tracks, and comprises, as mentioned, a step of removing, on both sides of the tracks 4, a continuous longitudinal portion 6a of the horizontal layer 6 to form a respective continuous longitudinal cavity 11, shown in Figures 2 and 3.
Following the above-mentioned removing step, which is carried out by means of a sort of milling of the material, waste material is produced, not illustrated in the accompanying drawings, in the form of dust and debris of various dimensions.
A suction step is actuated in order to remove the dust and debris.
Advantageously, a suction system, not illustrated, is located on board a suitable railway wagon which comprises one or more suction inlets, not illustrated, operated by operators in the proximity of the longitudinal cavity 11 for completely cleaning the zone processed.
The dust and debris sucked is then accumulated in a wagon and then conveyed to the outside of the site and disposed of in accordance with the relevant regulations.
A step of blowing pressurised air is then actuated, again close to each longitudinal cavity 11, in order to remove even the smallest traces of dust from the cavity 11.
Advantageously, the removal of the dust, even that with small grain size, has the aim of improving the adhesion of new resinous material in a fluid form to the walls of the cavity 11.
On a suitable railway wagon, not illustrated, there is an air compressor which supplies one or more blower openings, not illustrated, which are operated by operators in the proximity of the longitudinal cavity 11.
The rehabilitation method according to the invention comprises the step of injecting a resinous material 12 in a fluid form in the above-mentioned longitudinal cavity 11, in such a way as to reconstitute, as described in more detail below, following hardening of the resinous material 12, the continuity of the horizontal layer 6 of compact material.
The above-mentioned longitudinal cavity 11 thus constitutes the zone to receive new resinous material 12 in a fluid form.
Once the longitudinal cavity 11 constituting the zone designed to receive new resinous material 12 in a fluid form has been cleaned, there is a step of placing, inside the longitudinal cavities 11, a plurality of spacers 20 made of compact material distributed longitudinally.
The above-mentioned spacers 20 are distributed equidistant along the railway line 1 and are configured to guarantee the stability of the overlying tracks 4.
In other words, the main function of the spacers 20 is to guarantee, once the continuous longitudinal portions 6a of the horizontal layer 6 of comact material have been removed, the necessary stability for the tracks 4, whilst awaiting the rehabilitation of the horizontal layer 6.
Advantageously, the spacers 20 are made to support the passage of trains along the railway line 1 even in the absence of the resinous material 12 for filling the cavities 11.
The above-mentioned step of positioning the spacers 20 made of a compact material advantageously comprises the step of momentarily and locally lifting the part above said continuous longitudinal cavity 11, that is to say, the set of platforms 3 and tracks 4, for inserting the spacers 20 with interference.
In short, this lifting is performed locally, at the zone for inserting each spacer 20, advantageously by means of a hydraulic lift not illustrated. Advantageously, in order to rapidly guarantee the overall stability, there is the step of gluing the spacers 20 to the lower surface of the continuous longitudinal cavity 11.
In other words, the spacers 20 define supports with mechanical properties and elasticity comparable with the hardened resinous material 12, designed for the safety of the platforms 3 made of pre-compressed reinforced concrete.
Once the above-mentioned spacers 20 have been inserted along the longitudinal cavity 11 which constitutes the zone to receive new resinous material 12 in a fluid form, suitable panels 13 are arranged designed to contain the resinous material 12 in a fluid form.
According to the preferred embodiment illustrated in Figure 3, the above-mentioned panels 13 are made in the form of sheets with longitudinal extension, advantageously made of aluminium or steel, having a transversal "L" section.
The horizontal part of the L is fixed to the base foundation 3 made of reinforced concrete by means of suitable screws 14 which are suitably spaced from each other.
Advantageously, the screws 14 used are of the self-tapping type, in such a way as to simplify their application.
In short, the sheets defining the above-mentioned panels 13 are positioned one after the other longitudinally along the first direction D1, so as to form a continuous barrier, parallel to the above-mentioned longitudinal cavity 11 made below the tracks 4 and the pre-compressed reinforced concrete platforms 3.
Advantageously, the above-mentioned panels 13 are positioned at a predetermined distance d from the outer limit of the above-mentioned continuous longitudinal cavity 11, in such a way as to allow and facilitate the injection of the resinous material 12 in a fluid form inside the longitudinal cavity 11.
As clearly indicated in Figure 3, the predetermined distance d is to be measured along a direction D2 transversal to the above-mentioned first direction D1.
After setting up the above-mentioned panels 13, the step of injecting the resinous material in a liquid form is actuated, in such a way as to fill the longitudinal cavities 11, as illustrated by way of example in Figure 4.
In accordance with a preferred embodiment of the method according to the invention, the above-mentioned resinous material 12 in fluid form is advantageously obtained from two separate components.
Preferably, the above-mentioned resinous material 12 is defined by an elastic thixotropic two-component resin.
In order to proceed to the step of injecting resinous material 12 in a fluid form inside the longitudinal cavity 11, there is the step of mixing in-situ the components of the mixture which define the above-mentioned resinous material 12.
Advantageously, the step for mixing the two components is actuated at the same time as the injecting step.
With reference to Figure 5, a specially prepared railway carriage 15 is set up inside which respective tanks 16, 17 are placed for each of the two components of the mixture.
The railway wagon 15 is slidably engaged on the tracks 4 of the section of railway line 1 being processed.
Each tank 16, 17 has, at the bottom of it, a screw feeder type pushing element 18 which directs the single component of the mixture to an electronically controlled mixing unit 19.
At the mixing unit 19, respective flow meters, not illustrated, adjust the exact flow rate of each of the components of the mixture, so as to have a resinous material 12 in a fluid form at the outlet which is exactly as desired.
The thrust provided by the above-mentioned pushing means 18, also due to the viscosity of the resinous material, has been found experimentally to be sufficient to transfer the resinous material up to relative injection openings.
Preferably, according to the embodiment illustrated, also in order to increase the operating capacity of the plant, the tanks 16, 17 are duplicated inside the wagon 15.
Leading from the mixing unit 19 there are one or more flexible conduits, not illustrated, leading to the above-mentioned injection outlets which are advantageously operated by operators having the task of distributing the injection of resinous material along the longitudinal cavities 11. Advantageously, in order to simplify the placing of the resinous material 12 in a fluid form, especially in stretches of the railway line 1 which are non-perfectly flat, longitudinal pouring sections are defined, in such a way as to optimise the filling.
In other words, since the resinous material 12 is injected in a fluid form, it tends to level itself and, if the filled section is on a slope, there would be the risk of a non-uniform filling of the longitudinal cavity.
The formation of distinct longitudinal sections allows any possible nonuniformity to be limited.
For the purposes of this description, the expression "reconstruct the continuity of the layer of compact material" means that the new layer of resinous material 12 which is injected, once it has hardened, is able to withstand the loads supported by the previous horizontal layer 6 of compact material which the volume occupied.
Advantageously, the mixture of resinous material 12 used to inject in the continuous longitudinal cavity 11 offers better mechanical performance levels than the pre-existing material; in particular, in terms of compression strength, a resin has been advantageously selected which guarantees the perfect withstanding of the overlying load even without considering the portion of the layer 6 of compact material between the two longitudinal portions 6a removed.
In other words, for reasons of safety, the resinous material 12 injected has been selected in such a way as to guarantee, even only with the extension of the two lateral longitudinal portions 6a, at least the same compression strength guaranteed with the previous horizontal layer 6 in its entire extension.
This allows the actual conditions of the central part of the horizontal layer 6 of compact material to be ignored, which is not affected by the removal step according to the method. Even when this central part is under critical conditions, the optimum compression strength of the railway line is in any case ensured by the two longitudinal portions defined by the new injected resinous material 12.
The method according to the invention achieves the preset aims and brings important advantages.
The main advantage linked with use of the method according to the invention is due to the fact that it is possible to restore the effectiveness of the compact solid layer interposed between the base foundation and the pre-compressed reinforced concrete platforms without having to remove the tracks, thus reducing both the costs and the time connected with the operation.
Another advantage linked to the method according to the invention is due to the fact that the different steps can also be actuated even some time apart, in the meanwhile the railway line still being used.
For example, once the spacers 20 have been positioned inside the longitudinal cavities 11, the railway line 1 can withstand the passage of the trains and this advantageously allows the remaining steps to be performed also in successive stages, possibly with short interruptions to railway traffic, for example during the night.
All this makes it possible to rehabilitate the railway line in sections, a few steps at a time, without the need to carry out a prolonged stoppage of the operation of the line itself.

Claims

A method for the rehabilitation of the base of a railway line (1) having a horizontal layer (6) of compact material positioned below the tracks (4), comprising:
- a step of removing, on both sides of the tracks (4), a continuous longitudinal portion (6a) of the horizontal layer (6) for defining a relative continuous longitudinal cavity (11),

- a step of injecting a resinous material (12) in a fluid form in the longitudinal cavity (11), the resinous material (12) being such as to reconstitute, after hardening, the continuity of the horizontal layer (6) of compact material.
The method according to claim 1, characterised in that the step of removing the continuous longitudinal portion (6a) of compact material is actuated by a operating head (9) comprising a blade (10) with a substantially flat extension.
The method according to claim 2, characterised in that it comprises the step of taking away the material removed in the removal step, the step for taking away comprising the step of sucking the material removed.
The method according to any one of the preceding claims, wherein the resinous material (12) is obtained from at least two separate components, characterised in that it comprises a step of mixing the at least two components of the resinous material (12), the mixing step being actuated simultaneously with the injecting step.
The method according to claim 4, characterised in that the mixing step comprises the step of drawing the at least two separate components from respective tanks (16, 17) in situ.
The method according to any one of the preceding claims, characterised in that it comprises the step of placing, in the continuous longitudinal cavity (11), a plurality of spacers (20) made of compact material distributed longitudinally and configured for guaranteeing the stability of the overlying tracks (4).
The method according to claim 6, characterised in that the step of placing the plurality of spacers (20) made of a compact material comprises the step of momentarily lifting the part above the continuous longitudinal cavity (11), for inserting the spacers (20) with interference.
The method according to claim 6 or 7, characterised in that the step of placing the plurality of spacers (20) made of compact material comprises the step of gluing the thicknesses (20) to a lower surface of the continuous longitudinal cavity (11).
The method according to any one of the preceding claims, characterised in that it comprises the step of placing, along the continuous longitudinal cavity (11), a succession of rigid panels (13) configured for containing, during its hardening, the resinous material (12) injected in the liquid form.
A system for the rehabilitation of the base of a railway line (1) having a horizontal layer (6) of compact material positioned below the tracks, comprising:
- an apparatus (7) having a carriage (8) slidable along the tracks (4) of the railway line (1), an operating head (9) for removing at least partly the horizontal layer (6) of compact material, with the operating head (9) having a blade (10) having a substantially plane extension, the apparatus (7) being configured for making a continuous longitudinal cavity (11) in the base;

- a railway wagon (15) configured for housing inside it respective tanks (16, 17) containing components of a mixture constituting a resinous material (12) to be injected in a liquid form inside the longitudinal cavity (11).