This invention relates to a method for consolidating railway roadbeds in general and an apparatus for implementing the method.

An aspect of particular importance in terms of work directed towards railway operation improvement, with regard both to increased train speed and to increased passenger and goods carrying capacity, is the consolidation of railway roadbeds, which with continuous use and the passing of time tend to degrade due to vibration, freezing and thawing, water absorption, swelling, excessive deformation, etc-

This consolidation work, which can be either localized or systematic along the entire railway line, is currently done on an artesan basis and involves a series of drawbacks which the present invention proposes to overcome. One of the drawbacks of current methods is the excessive time required for their implementa ion, this time often not being compatible with the requirement of regular railway operat ion.

A further drawback is the need for access areas external to the embankment to be consolidated, such areas not always being available and in any event requiring expropria ion or at least the obtaining of the necessary authoriza ion. In addition, for particular types of embankment such access

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areas are not available with the result that the work involved requires the total interruption of the railway line-

A further drawback is that current consolida ion operations often require the embankment to be cut away to form a. working surface from which the work can be carried out, this inevitably further disturbing the stability of the embankment and resulting in long periods of limited train speed along a structure which is already in a state of unstable equilibrium. The object of the invention is to effect consolidation of railway roadbeds and embankment in general in a very simple, rapid, effective and economical manner, which in part icular:

- does not require ecternal access areas, and instead merely uses the railway line itself,

- can be totally automated,

- can be implemented without any removal of the railway superstructure,

- prevents any contamina ion of the ballast with fine material .

This and further objects which will be apparent from the desσriprion given hereinafter are attained according to the invention by a method for consolida ing railway roadbeds and

embankments in general, characterised by:

- forming holes at predere ined distances apart in the embankment to be consolidated, the hole dimensions depending on the particular work to be carried out,

- feeding a hydraulic concrete mix into each hole; and

- progressively compacting the concrete mix from the lower layers towards the upper opening of the hole.

To implement the aforesaid method the invention provides for the use of an apparatus comprising a truck mobile along the rails of the railway line and provided with:

- at least one lower unit mounted on a mobile arm,

- a boring unit comprising a substan ially cylindrical boring tool provided with a boring bit,

- means for inctroducint a hydraulic concrete mix into each hole formed by said boring tool,

- means for compacting said concrete mix from the lower layers upwards-

Two preferred embodiments of the present invention are described hereinafter with reference to the accompanying drawings in which:

Figure 1 is a. side view of a railway truck provided with a first embodiment of the apparatus for implementing the method of the invention, shown during

transportation, Figure 2 is a plan view thereof, Figure 3 shows the rear end of the truck, with the apparatus in its working state, Figure 4 is an enlarged view of the boring tool and its support structure, Figure 5 is a plan view of the end of the railway truck on the line V-V of figure 3, Figure 6 is the same view as figure 5 during automatic advancement ,

Figure 7 is a cross-sec ion through the automatic truck moving device during its operation, Figure 8 shows it during its recovery,

Figure 9 is a side view of a railway truck provided with a second embodiment of the apparatus for implementing the method of the invention, shown during transportation, Figure 10 is a plan view thereof,

Figure 11 is the same view as figure 10 but showing a modification thereto,

Figure 12 is a side view thereof in the working state,

Figure 13 is a plan view thereof,

Figures 14 to 17 are enlarged vertical sections showing four

successive stages in the implementa ion of the second e hos, Figure 18 is a plan view of railway line embankment comprising piles and miσropiles according to the inven ion, and

Figure 19 is a vertical section on the line XVI 11 -XVI11 of figure 18- As can be seen from the figures the pile insertion apparatus acording to the inven ion is mounted on a railway truck 1, for transposr t ion along the railway line 2. In the embodiment shown in figure 1 to 8 this apparatus, provided for effecting consolida ion by "miσropiles", ie piles having a length of between 100 cm and 150 cm and a diameter of about 15 cm, comprises two hydraulic boring units 3, each comprising a tubular support 4 which can be adjusted longitudinally relative to a counter-support 5, under the control of a hydraulic cylinder-piston unit 6-

The counter-support 5 is hinged to a frame 7, to which it is also conneσted via a hydraulic cylinder-piston unit 8 or its inclination in the vertical plane, and is rotatable about the floor of the fruck 1 together with said frame 7 under the control of a third hydraulic cylinder-piston unit 9.

A hydraulic cylinder-piston unit 11 provided with a boring bit is slidable along the support 4, which is provided lowerly with a plate 4 for resting on the ground during working. Below the floor of the railway truck 1 there is provided a device for moving the truck- It comprises a telescopic frame 12 vertically mobile under the control of a hydraulic cylinder-piston unit 13 and provided with a lower cross- member 14 to which four self-centering hydraulic clamps 15 are applied to act on the rails of the railway line 2- The telescopic frame 12 is also connected to the railway truck 1 via a further longitudinal cylinder-piston unit 16, for its longitudinal movement.

The opera ion of this embodiment of the apparatus according to the invention is as follows: the railway truck is firstly positioned on the railway line 2 to correspond to the section to be consolidated. During this stage it is advantageous for the railway truck to form part of a train which also comprises further truσks for material, equipment and personnel transport, to provide total self- sufficiency in operation.

During this transfer, the supports 4 for the two boring units 3 lie horizontally on the floor of the truck 1.

When the truck has reached the line section to be consolidated, the cylinder-piston units 8 are firstly operated to arrange the tubular supports 4 in their vertical working position. The cylinder-piston units 6 are then operated to lower the supports 4 relative to the counter- support 5, until their lower plate 10 rests on the ballast of the railway line 2.

If necessary, the σyl inder-pis on units 9 are then operated to horizontally rotate the corresposnding frames 7 until the boring bit of each boring unit 3 is in the correct position for inserting a. micropile-

At this point the corresponding hydraulic cylinder- piston unit 11 is operated, by which it causes the bit to penetrate progressively firstly into the ballast and then into the embankment. The penetration into the ballast is accompanied by the penetration of a jacket 17 which surrounds the bit and prevents possible slippage of the ballast when the bit is extracted for filling the hole. This problem does not arise for the underlying embankment because of its cohesion and self-sustaining characteristics.

On termination of boring, the hole is filled by pouring into it through the metal jacket 17 catalyzed mix prepared separately by suitabl mixing together one or more types of

sand, blast furnace slag and a specific setting agent- This filling is accomplished in several pourings, after each of which the previously poured mix is compacted by the boring bit . When the pouring and compacting of the catalyzed mix is complete, the bit of the boring unit 3 is extracted and the jacket 17 withdrawn, leaving in place a cylindrical mϊcropile of the desired length, with its upper end at the level of the ballast under-surface- After the jacket has been extracted the cylinder-piston unit 13 is operated to lower the cross-member 14 such that the clamps 15 are able to clamp it to the rails 2- When clamped, the longitudinal cylinder-piston unit 16 is operated to move the truck 1 along the railway line by a predetermined distance, after which the clamps 15 are released from the rails 2, the cross-member 14 is raised and the telescopic frame 12 returned to the truck 1, to arrange the apparatus for the next operating σyσle-

To insert the next iσropile, or rather the next pair of miσropiles by the two boring units 3, it may be necessary depending on the position of this next pair relative to the previous pair (longit dinally aligned or at an angle) to rotate the rotatable frame 7 about the longitudinal axis of

the truck 1, this being achieved by operating the cylinder- piston units 9.

To automate the various operations it is preferable for the operating sequence of the various cylinder-piston units to be controlled by computer, which would then provide the various σommands required for the σhosen operating cycle, the truck advancement movement and the mutual arrangement of successive miσropiles.

From the aforegoing it is apparent that the method according to the invention and the apparatus for its implementation are extremely advantageous, in that:

- they enable the ground immediately below the ballast to be reclaimed and consolidated without having to remove any of the railway superstructure, - they eliminate the intermediate stage of other methods, ie the operations involved from the formation of the pile to the hardening of the mix, with consequent elimination of the risk of possibile dislodging of the track, resulting in slow-down and irregularity of railway traffic, - they prevent contamination of the ballast by fine material during consolidation, and

- they enable considerable economy to be obtained over convention methods.

Figure 9 to 17 show a different embodiment of the apparatus according to the invention, suitable for inserting larger piles generally of between 300 and 750 cm in length and between 20 and 30 cm in diameter- The apparatus in this case comprises on a. railway truck

21 two hydraulic telesσopiσ jib cranes 22- Each of these is mounted on a frame 23 slidable on transverse guides 24 and moved therealong by a pair of hydraulic cylinder-piston units 25- The frame 23 is also provided with two telescopic legs 26 for stabilizing the frame when in its working state, ie projecting laterally from the truck 21 -

The two cranes can be disposed on each side of the truck 21 (see figure 10) or on one and the same side (see figure 11) acσording to the partiσular form of the railroad- Eaσh crane supports a vibrator 27 and a forming tube 28 for the pile to be formed. The lower end of the forming tube is provided with a double-valved closure deviσe 29 (see figure 14-17).

The operation of this seσond embodiment of the apparatus according to the invention ia as follows: the railway truck preferably together with other trucks forming a train to allow totally self-sufficient operation is transferred onto the section of railway line to be

consolidated, after which the two cranes are moved along together with their frames 23 by the respective cylinder- piston units, and then stabilized by the legs 26 on reaching their working position. The position of the truck 21 on the rails 2 and the position of each crane on the truck 21 are such that the two suspended forming tubes are vertical exactly above the point at which a pile is to be inserted-

After the lower end of the forming tube has been rested on the surface of the ground, the vibrators 27 are operated so that each of these by acting on the underlying forming tube 28 drives it into the fround to the required depth, but without removing material- On reaching this depth, the catalyzed mix composed as in the previous case of one or more types of sand, blast furnace slag and a setting agent, and made up preferably in a truck forming part of the train, is fed into the forming tube- These operation are simplified if the upper end of said forming tube is provided with a charging hopper 30-

Having completed the charge, the forming tube is extracted through successive distances, this lifting causing the lower valve device to open and a quantity of catalyzed mix to emerge corresponding to the extend of lifting. After each lifting step the forming tube 28 is slightly lowered to

close the two valves and allow them to compact the underlying mix- In practice, when extraction is complete a pile will have been obtained which is completely fixed into the ground and cooperates with other piles to provide the desired degree of consolidation.

The piles can be formed si ul aneousl on both sides of the embankment (in the σase of single track lines) or firstly on one side and then on the other (in the σase of double track 1 ines) - For more effective consolidation, piles and micropiles can be used simultaneously, the former being generally inserted into the embankment in a position below the ballast, and the latter also being inserted into the embankment but outside the ballast, as σan be seen in figures 15 and 16.