EP3754154A1 - Machine for drilling a floor covered with a porous layer, and corresponding method - Google Patents

Abstract

The invention relates to a machine for drilling, under circulation of fluid, a ground (S) covered with a porous layer (P) in which the machine comprises: - a drive head (14) for rotating a rod of drilling (18), and - means for circulating a drilling fluid configured to inject a drilling fluid through the drill pipe (18). The machine is also configured to insert, through the porous layer (P) , a protection tube (22) extending around the drill rod (18) and leaving an intermediate tubular space (29) between the drill rod (18) and the protection tube (22), and in which the machine also comprises first means for collecting (30) the drilling fluid configured, during the insertion of the protection tube (22) through the porous layer (P), to suck, from the upper end of the protection tube (22), the drilling fluid coming from the drill pipe and present at the lower end of the protective pipe ection (22). The invention also relates to a work train comprising such a machine for drilling, and the corresponding drilling method.

Description

Technical area

The present invention relates to the field of drilling techniques in the ground, and more particularly to the so-called small perforation drilling techniques under fluid circulation.

Prior art

It is known, in order to install an anchor, that is to say a micro-pile, in a ground, to first perform a borehole by rotating a cutting tool which will excavate the ground. During drilling, a liquid, called drilling fluid, is usually injected to cool and lubricate the cutting tool and to remove cuttings.

A reinforcement is then placed in the borehole, or else the tool is left in the borehole with its drive rod, before injecting a sealing grout therein.

However, such a technique of drilling under fluid circulation can damage the ground of the workplace, or platform, in particular because of the infiltration of the drilling fluid all around the borehole and because of the mechanical stresses exerted on the layer. of surface. This is particularly problematic in the case of soils having a porous layer which must be preserved all around the borehole, such as boreholes on railway installations which have an upper layer of ballast.

One solution to protect a platform against infiltration is to recover the fluid at the drilling head. Such a solution is usually done by digging a pit in which a suction (pump) is immersed. Alternatively, there are also bins drilled to the right of the borehole and fitted with a suction mouth, which makes it possible to avoid the digging of the pit.

However, the digging of a pit or the installation of drilled trays in line with the borehole is restrictive and makes the borehole dependent on the proper completion of previous steps.

Furthermore, in order to protect the surface layer of land, it is also possible to use casing on the layer concerned.

However, for the sealing by casing to be effective, it is generally necessary to use a material provided with a double head, that is to say allowing independent rotation of the tube and the rod. However, such a double-headed equipment is expensive and bulky, which limits its ease of movement.

Disclosure of the invention

The present invention aims to solve the various technical problems mentioned above. In particular, the present invention aims to provide a machine making it possible to limit the infiltration of drilling fluid and to preserve the upper layer of the drilled soil. More specifically, the present invention aims to provide a drilling machine which does not allow the platform to be destructured and which does not require the installation of a recovery tank.

Thus, according to one aspect, there is proposed a machine for drilling, under fluid circulation, a ground covered with a porous layer, for example a layer of ballast. The machine includes a drive head for rotating a drill pipe, and means for circulating a drilling fluid configured to inject a drilling fluid through the drill pipe.

The machine is also configured to insert, through the porous layer, a protective tube extending around the drill pipe and leaving an intermediate tubular space between the drill pipe and the protective pipe. The machine also comprises first means for recovering the drilling fluid configured, during the insertion of the protection tube through the porous layer, to suck, from the upper end of the protection tube, the drilling fluid coming from the drill rod, present at the lower end of the protective tube and rising, preferably, via said intermediate tubular space.

Thus, the machine according to the present invention uses a protective casing, in addition to the drill rod, without using a double head, to maintain the integrity of the platform, and in particular of the porous layer, and ensures sealing by continuous suction at the top of the casing. It is then possible to have an autonomous use of the machine not requiring a previous step, such as that the establishment of a pit or drilled tanks, while limiting the infiltration of drilling fluid, in particular in the porous layer.

Preferably, the machine also comprises second means for recovering the drilling fluid, the second recovery means being configured to evacuate the drilling fluid coming from the drill rod and coming out through the upper end of the protection tube, preferably via said intercalary tubular space, when the protective tube is positioned through the porous layer.

When the porous layer has been crossed, the protective tube remains in place, to continue to isolate the borehole, and in particular the circulation of drilling fluid, from the porous layer. Moreover, the protective tube is detached from the machine, and in particular from the drive head. At the same time, the drilling tool continues to dig, under the porous layer, with a circulation of fluid: the latter is then recovered through the tubular space interposed between the protection tube and the drilling rod.

Preferably, the first and second recovery means comprise a common pump and a connecting means configured to connect the common pump to the first recovery means during the insertion of the protection tube through the porous layer, and to connect the common pump. to the second recovery means when the protective tube is positioned through the porous layer.

As indicated previously, the drilling fluid is not recovered in the same way in the different stages of drilling, in particular because the protection tube is gradually inserted with the drill rod at first, then remains static in a second. time, when positioned through the drill bed. Thus, the recovery means used are different according to the drilling stages, but can be connected to the same pumping means in order to limit the costs and the volume of the machine.

Preferably, the second recovery means are configured to be positioned at the upper end of the protection tube when the protection tube is positioned through the porous layer, the second recovery means comprising a reservoir, preferably in the form of a crown, into which the drilling fluid coming out of the protection tube is poured, and a peripheral seal, preferably circular, creating a seal between the reservoir and the outer wall of the protection tube.

Once the protective tube has been positioned through the porous layer, the upper end of the latter generally comes flush with the surface of the drilled soil. Thus, the drilling fluid injected at the level of the drilling tool can go up alone, under the effect of the pressure and / or the flow, to said upper end of the protective tube. In order to recover this drilling fluid, it is then no longer sufficient to collect it in a reservoir situated at the upper end of the protection tube, and to suck it up with a pump.

Preferably, the peripheral seal is an inflatable seal. The inflatable seal allows easy installation at the upper end of the protection tube, while ensuring a desired seal by controlling the pressure applied in the inflatable seal.

Preferably, the drive head is configured to also drive the protection tube in rotation, preferably at the same time as the drill rod, during the insertion of the protection tube through the porous layer.

The rotational drive of the protective tube makes it easier to insert it into the ground, and in particular through the porous layer, at the same time as the drill rod. Such a drive does not require double head equipment, but can be done simultaneously with the drill rod. Once the protection tube is positioned, it is then sufficient to detach it from the drive head to leave it in place, and to continue only with the drill rod.

Preferably, the drive head comprises means for mounting the drill rod, having a first determined diameter, and means for mounting the protection tube, having a second determined diameter greater than the first determined diameter.

In such an embodiment, the drill rod and the protective tube are mounted on the head by mounting means which may differ only in their diameter. This facilitates the use of the machine, allowing installation and removal procedures which are similar for the protection tube and the drill pipe.

Preferably, the first means for recovering the fluid are mounted on the drive head, for example above the means for mounting the protection tube.

Such a mounting of the first recovery means on the drive head makes it possible to keep the suction at the upper end of the protection tube throughout the duration of the insertion of said protection tube through the porous layer and the sub-layer. underlying.

According to another aspect, there is also proposed a work train comprising a machine for drilling a ground covered with a porous layer as described above.

As indicated above, the drilling machine has been designed so as to allow the use of standard equipment, and not heavy equipment such as a double head or specific duplicate equipment for the protective tube on the one hand and for the drill rod on the other hand. It then becomes possible to install it on a railway vehicle, such as a work train, in order to be able to move it along the site, as the work progresses.

Preferably, the work train comprises a drilling fluid reservoir connected to the drive head, means for sucking up the drilling fluid configured to be connected to the recovery means, and means for supplying a cement grout configured. to be connected to the drive head.

Such a work train can thus transport the various elements necessary for the operation of the machine for drilling and for carrying out the work.

Preferably, the works train also comprises a sludge recovery system, for example a settling tank, mounted downstream of the recovery means.

In particular, the sludge recovery system can be configured to operate with the sludge from the first recovery means and sludge from the second recovery means. The sludge recovery system makes it possible in particular to recover part of the drilling fluid directly on the work train for reuse in situ, and makes it possible to store the material removed during drilling in order to limit the impact of the work on the site.

According to another aspect, there is also proposed a method for drilling, under circulation of fluid, in a ground covered with a porous layer, for example a layer of ballast. According to the method, a drill pipe is rotated, and a drilling fluid is injected through the drill pipe, preferably during the rotation of the drill pipe.

During a first step, a protective tube extending around the drill pipe and leaving a tubular space between the drill pipe and the protective pipe is inserted through the porous layer, and suction is carried out from there. the upper end of the protection tube, the drilling fluid coming from the drill rod, present at the lower end of the protection tube and rising, preferably, via said intermediate tubular space, during the insertion of the protection tube through the porous layer.

Preferably, during a second step, when the protection tube is positioned through the porous layer, the protection tube is left in place and the drilling fluid coming from the drill rod and emerging through the upper end of the tube is evacuated. protection, preferably via said intermediate tubular space.

Preferably, during the first step, the protective tube is driven at the same time as a first part of the drill rod equipped, at its end, with a tool, then, during the second step, a second part of the rod is assembled. to the first drill pipe part and the two drill pipe parts are rotated while injecting a drilling fluid through and discharging the fluid exiting through the upper end of the protection tube, preferably via said intercalary tubular space.

Brief description of the drawings

• [ Fig. 1 ] The figure 1 shows a perspective view of the machine for drilling according to the invention;
• [ Fig. 2 ] The figure 2 details the flow of fluids from the machine for drilling during the installation of the protection tube;
• [ Fig. 3 ] The figure 3 illustrates the two machine configurations for drilling when installing the protection tube and when the protection tube is installed;
• [ Fig. 4 ] The figure 4 illustrates the different successive steps in implementing the drilling method with the machine for drilling illustrated on figure 1 ; and
• [ Fig. 5 ] The figure 5 illustrates part of a work train with a drilling machine as illustrated on figure 1 .

Description of embodiments

On the figure 1 , there is shown a machine for drilling 1 according to the present invention. The machine for drilling 1 thus comprises a support 2 on which a frame 4 is mounted.

The support 2 is intended to come, integrally, on a railway carrier (not shown), conventionally a railway car, making it possible to transport and route the machine for drilling 1 along the rails R of a railway track. Such an embodiment is particularly advantageous when the drilling machine 1 is used to install catenary pylon micropiles along the railway track, through the ballast layer.

In order to deploy and store the machine for drilling 1 on the wagon, the frame 4 is rotatably mounted on the support 2, relative to a vertical axis: it is thus possible to position the drilling tool next to the rail carrier , or else above the rail carrier, depending on whether the drilling machine 1 must install a pylon micro-pile or else must be moved.

The drilling machine 1 also comprises a mast 6 extending in a longitudinal direction, and mounted to pivot on the frame 4, relative to a horizontal axis, for example via jacks 8. The jacks 8 thus make it possible to position the mast 6 horizontally, in particular above the rail carrier, when the drilling machine 1 is to be moved, or else vertically, as illustrated in the figure figure 1 , when the machine for drilling 1 needs to install a pylon micro-pile.

In the drilling position, as shown in figure 1 , the mast 6 has a lower end 6a intended to come to rest on the surface to be drilled.

The drilling machine 1 further comprises a carriage 10 slidably mounted along the mast 6. The carriage 10 can be moved along the mast 6 by means known elsewhere and not shown here.

The carriage 10 comprises in particular a rotation table 12 configured to drive in rotation a drive head 14 on which the drilling tool will be mounted. As will be explained below, the drilling tool of the present machine for drilling 1 comprises on the one hand a drilling rod and on the other hand a protective tube independent of the drilling rod and surrounding the latter at the level of the upper portion of the borehole.

In particular, and as illustrated in figure 2 , the drive head 14 comprises in particular first mounting means 16, for example an internal thread, configured to allow the mounting of a drill rod 18, comprising a corresponding external thread, on the drive head 14. The head drive 14 also comprises second mounting means 20, for example an external thread, configured to allow the mounting of a protection tube 22, comprising a corresponding thread, on the drive head 14.

As can be seen, the first mounting means 16 and the second mounting means 20 are arranged coaxially on the drive head 14, in order to obtain a mounting of the drill rod 18 parallel to the mounting of the protection tube 22. , and include different diameters corresponding to those of the drill rod 18 and the protection tube 22. In particular, the drill rod 18 and the protection tube 22 are driven simultaneously, together, by the drive head 14 when ' they are mounted on the means 16 and 20 respectively.

In order to facilitate drilling, the drilling machine 1 also comprises a circuit for circulating a drilling fluid. The drilling fluid can for example be water, and is circulated by the drilling machine 1 in the drilling zone in order to extract the drilled material therefrom.

The drive head 14 thus comprises a supply channel 24 for drilling fluid connected to means for supplying and circulating under pressure a drilling fluid (not shown). The drill pipe 18 also includes an axial channel 26 which comes into fluid communication with the supply channel 24 of the drive head 14 when the drill pipe 18 is mounted on the drive head 14. The drilling fluid is thus injected under pressure inside the drilling rod 18, in order to come out at the other end of the drilling rod 18 on which is mounted a cutting tool 28 (see figure 3 ).

In order to protect the platform in which the drilling is carried out, and in particular in order to prevent the drilling fluid, with the material which it entrains, from spreading around the drilling zone, and in particular the porous layer P ballast, the protection tube 22 is designed with an inner diameter greater than the outer diameter of the drill rod 18, so as to create, when the drill rod 18 and the protection tube 22 are mounted on the drive head 14, an intermediate tubular space 29 extending from the lower end of the protection tube 22 to the first and second mounting means 16, 20 of the drive head 14.

Furthermore, the drive head 14 is configured to extend the intercalary tubular space 29 beyond the first and second mounting means 16, 20, to the first means 30 for collecting drilling fluid. As illustrated in the configuration (1) of the figure 3 , the first recovery means 30 are mounted on the drive head 14, above the first and second mounting means 16, 20, and make it possible to recover, or to suck thanks to suction means not shown , the drilling fluid loaded with drilled material and rising from the bottom of the borehole via the intercalated tubular space 29. This recovery, or suction, of the drilling fluid loaded with drilled material takes place as it goes, and throughout the descent of the drill rod 18 and of the protective tube 22 in the ground, and more particularly in the porous upper layer P of ballast.

Moreover, and as illustrated in the configuration (2) of the figure 3 , the machine for drilling 1 also comprises second recovery means 32 mounted at the lower end 6a of the mast 6 and configured to recover, or suck, the drilling fluid loaded with drilled material leaving the tube protection 22 when the latter is positioned through the porous layer P of ballast and is detached from the drive head 14. In particular, the machine for drilling 1 can comprise suction means (not shown), for example a single pump configured to be connected to the first recovery means 30 and / or to the second recovery means 32 according to the stage of the drilling process. For example, the suction means can comprise a connection means to come to be connected to the first recovery means 30 then to the second recovery means 32.

The second recovery means 32 may for example comprise a reservoir in the form of a ring mounted around the protection tube 22, and a circular seal, preferably inflatable, configured to create a seal between the outer wall of the protection tube 22 and the reservoir of the second recovery means 32. The drilling fluid, loaded with drilled material, exiting through the upper end of the protection tube 22 then flows into the reservoir of the second recovery means 32 before being, for example , sucked towards a treatment means (not shown) such as a settling tank making it possible to separate the drilling fluid and the drilled material then to reuse the drilling fluid.

• A l'étape (A), le mât 6 est positionné verticalement avec son extrémité inférieure 6a en appui sur la surface à forer. Le chariot 10 entraînant en translation la tête d'entraînement est positionné en haut du mât 6, avec la tête d'entraînement 14 située au droit de la zone à forer.
• A l'étape (B), la tête d'entraînement 14 est pivotée, au niveau du chariot 10, de 90° afin de libérer l'accès à la zone à forer.
• A l'étape (C), le tube de protection 22 est positionné au-dessus de la zone à forer, à l'extrémité inférieure 6a du mât 6 formant un guide pour le tube de protection 22.
• A l'étape (D), la première portion de la tige de forage 18, qui comporte à son extrémité l'outil de coupe 28 et qui constitue une armature avec outil perdu, est positionnée à l'intérieur du tube de protection 22, comme cela est visible sur la portion représentée en coupe de l'étape (D).
• A l'étape (E), la tête d'entraînement 14 est à nouveau pivotée, au niveau du chariot 10, de 90° pour revenir au droit de la zone à forer, au-dessus du tube de protection 22 et de la tige de forage 18.
• A l'étape (F), le chariot 10 est descendu de manière à permettre le montage de la tige de forage 18 sur les premiers moyens de montage 16 correspondant, puis le montage du tube de protection 22 sur les deuxièmes moyens de montage 20 correspondant.
  Une fois le tube de protection 22 et la tige de forage 18 montés sur la tête d'entraînement 14, ceux-ci sont mis en rotation par la tête d'entraînement en même temps que le chariot 10 descend le long du mât 6. La tige de forage 18 et le tube de protection 22 commencent donc à forer la couche poreuse P de ballast et à s'enfoncer à l'intérieur, jusqu'à ce que le tube de protection 22 soit enfoncé dans et à travers la couche poreuse P de ballast (étape (G)). Pendant toute l'étape (F), le fluide de forage est, d'une part, injecté, via la tête d'entraînement 14, à travers la tige de forage 18 pour ressortir au niveau de l'outil de coupe 28, puis, d'autre part, ré-aspiré depuis l'extrémité supérieure du tube de protection 22, via l'espace tubulaire intercalaire, par les premiers moyens de récupération 30 montés sur la tête d'entraînement 14. En effet, le fluide de forage devant « remonter » toute la longueur du tube de protection 22 jusqu'à la tête d'entraînement qui peut se situer très au-dessus de la surface à forer, la pression d'injection du fluide de forage peut s'avérer insuffisante, de sorte qu'une aspiration forcée au niveau des premiers moyens de récupération 30 est alors nécessaire. Ainsi, tout au long de l'étape (F), le fluide de forage est récupéré au fur et à mesure de son injection dans la tige de forage 18, ce qui permet de limiter l'impact de sa circulation sur la zone entourant le forage.
• A l'étape (G), le tube de protection 22 est positionné au travers de la couche poreuse P de ballast, et peut alors être désolidarisé de la tête d'entraînement 14. Une fois désolidarisé, les deuxièmes moyens de récupération 32 peuvent être solidarisés sur le tube de protection 22, par exemple le joint annulaire gonflable peut être gonflé de manière à rendre étanche la liaison entre le tube de protection 22 et le réservoir des deuxièmes moyens de récupérations 32.
• A l'étape (H), le chariot 10 portant la tête d'entraînement 14 est d'abord remonté partiellement de manière à faire remonter la tige de forage 18 suffisamment pour pouvoir la désolidariser à son tour de la tête d'entraînement 14, puis le chariot 10 est remonté en haut du mât 6.
• A l'étape (I), la tête d'entraînement 14 est pivotée, au niveau du chariot 10, de 90° afin de libérer l'accès à la zone à forer, et une deuxième portion de la tige de forage 18 est positionnée puis montée sur la première portion de la tige de forage 18.
• A l'étape (J), la tête d'entraînement 14 est à nouveau pivotée, au niveau du chariot 10, de 90° pour revenir au droit de la zone à forer, au-dessus de la tige de forage 18 (qui comporte à présent deux portions), et celle-ci est alors montée sur la tête d'entraînement 14.
• A l'étape (K), la tige de forage 18 est mise en rotation par la tête d'entraînement 14 en même temps que le chariot 10 descend le long du mât 6. La tige de forage 18 continue donc à forer le sol S, au-delà de l'extrémité inférieure du tube de protection 22. Pendant toute l'étape (K), le fluide de forage est, d'une part, injecté, via la tête d'entraînement 14, à travers la tige de forage 18 pour ressortir au niveau de l'outil de coupe 28, puis, d'autre part, circule, via l'espace tubulaire intercalaire, jusqu'à l'extrémité supérieure du tube de protection 22. L'extrémité supérieure du tube de protection 22 étant libre et se situant légèrement au-dessus de la surface forée, le fluide de forage chargé en matière forée peut alors ressortir tout seul, sous l'effet de la pression d'injection, et venir couler dans le réservoir des deuxièmes moyens de récupération 32 pour être aspiré ensuite par les moyens d'aspiration. Ainsi, tout au long de l'étape (K), le fluide de forage est récupéré au fur et à mesure de son injection dans la tige de forage 18, ce qui permet de limiter l'impact de sa circulation sur la zone entourant le forage.
• A l'étape (L), le chariot 10 portant la tête d'entraînement 14 est d'abord remonté partiellement de manière à faire remonter la tige de forage 18 suffisamment pour pouvoir la désolidariser de la tête d'entraînement 14, puis le chariot 10 est complètement remonté en haut du mât 6 de manière à pouvoir reproduire, autant de fois que souhaitées, les étapes (I) à (L).

Using the figure 4 , we will now describe an example of a method of drilling, under circulation of fluid, a soil S covered with a porous layer P, for example ballast.

• In step (A), the mast 6 is positioned vertically with its lower end 6a resting on the surface to be drilled. The carriage 10 driving the drive head in translation is positioned at the top of the mast 6, with the drive head 14 located to the right of the zone to be drilled.
• In step (B), the drive head 14 is rotated, at the level of the carriage 10, by 90 ° in order to free access to the zone to be drilled.
• In step (C), the protection tube 22 is positioned above the zone to be drilled, at the lower end 6a of the mast 6 forming a guide for the protection tube 22.
• In step (D), the first portion of the drill rod 18, which comprises at its end the cutting tool 28 and which constitutes a reinforcement with lost tool, is positioned inside the protection tube 22, as can be seen on the portion shown in section of step (D).
• In step (E), the drive head 14 is again rotated, at the level of the carriage 10, by 90 ° to return to the right of the zone to be drilled, above the protection tube 22 and the rod drilling 18.
• In step (F), the carriage 10 is lowered so as to allow the mounting of the drilling rod 18 on the first corresponding mounting means 16, then the mounting of the protection tube 22 on the second corresponding mounting means 20. .
  Once the protective tube 22 and the drill rod 18 mounted on the drive head 14, they are rotated by the drive head at the same time as the carriage 10 descends along the mast 6. The Drill rod 18 and the protection tube 22 therefore start to drill the porous P layer of ballast and sink into it, until the protection tube 22 is pushed into and through the porous P layer ballast (step (G)). Throughout step (F), the drilling fluid is, on the one hand, injected, via the drive head 14, through the drilling rod 18 to exit at the level of the cutting tool 28, then , on the other hand, re-sucked from the upper end of the protection tube 22, via the intermediate tubular space, by the first recovery means 30 mounted on the drive head 14. In fact, the drilling fluid having to "go up" the entire length of the protective tube 22 up to the drive head which may be located far above the surface to be drilled, the injection pressure of the drilling fluid may prove to be insufficient, from so that a forced suction at the first recovery means 30 is then necessary. Thus, throughout step (F), the drilling fluid is recovered as it is injected into the drill rod 18, which makes it possible to limit the impact of its circulation on the area surrounding the drilling.
• In step (G), the protection tube 22 is positioned through the porous layer P of ballast, and can then be separated from the drive head 14. Once separated, the second recovery means 32 can be separated. secured to the protection tube 22, for example the inflatable annular seal can be inflated so as to seal the connection between the protective tube 22 and the reservoir of the second recovery means 32.
• In step (H), the carriage 10 carrying the drive head 14 is first partially reassembled so as to raise the drill rod 18 sufficiently to be able to separate it in turn from the drive head 14, then the carriage 10 is reassembled at the top of the mast 6.
• In step (I), the drive head 14 is rotated, at the level of the carriage 10, by 90 ° in order to free access to the zone to be drilled, and a second portion of the drill rod 18 is positioned then mounted on the first portion of the drill rod 18.
• In step (J), the drive head 14 is again pivoted, at the level of the carriage 10, by 90 ° to return to the right of the zone to be drilled, above the drill rod 18 (which comprises now two portions), and this is then mounted on the drive head 14.
• In step (K), the drill rod 18 is rotated by the drive head 14 at the same time as the carriage 10 descends along the mast 6. The drill rod 18 therefore continues to drill the soil S , beyond the lower end of the protection tube 22. During the entire step (K), the drilling fluid is, on the one hand, injected, via the drive head 14, through the rod. drilling 18 to emerge at the level of the cutting tool 28, then, on the other hand, circulates, via the intermediate tubular space, to the upper end of the protection tube 22. The upper end of the protection tube protection 22 being free and located slightly above the drilled surface, the drilling fluid loaded with drilled material can then come out on its own, under the effect of the injection pressure, and flow into the reservoir of the second means recovery 32 to then be sucked by the suction means. Thus, throughout step (K), the drilling fluid is recovered as it is injected into the drill rod 18, which makes it possible to limit the impact of its circulation on the zone surrounding the drilling.
• In step (L), the carriage 10 carrying the drive head 14 is first partially reassembled so as to raise the drill rod 18 sufficiently to be able to separate it from the drive head 14, then the carriage 10 is completely reassembled at the top of the mast 6 so as to be able to reproduce, as many times as desired, steps (I) to (L).

Once the installation steps of the drill rod 18 have been carried out, a cement grout can then be injected into the drill rod in order to seal the latter in the soil S and thus obtain a catenary pylon micro-pile.

Thus, a micropile is obtained formed on the one hand by a drill rod and on the other hand by a protective tube which reinforces the retention of the drill rod in the ground. The protection tube is positioned in the ground, through a layer of ballast, without the latter or the surface of the zone to be drilled being impacted by the drilling carried out.

Moreover, thanks to its compactness, in particular because of its simple head, and its limited weight, the drilling machine 1 is suitable for being installed on a railway wagon and for moving quickly, with significant bends. Thus, it is possible to obtain a work train 34, part of which is illustrated on the figure 5 , comprising a machine for drilling 1 as described above, and making it possible to install the micro-piles of catenary pylons along the railway track on which it runs.

The work train 34 can thus comprise, in addition to the machine for drilling 1, means for supplying and circulating, under pressure, a drilling fluid (not shown), connected to the drive head, means Cement grout supplies (not shown) configured to connect to drive head 14 when sealing drill rod 18 in the borehole.

The work train 34 may also include suction means 36 for the drilling fluid loaded with drilled material, configured to be connected to the first or to the second recovery means 30, 32, as well as a settling tank 38 mounted downstream of the suction means 36 and allowing separation of the drilling fluid and the drilled material, in order to allow reuse of the drilling fluid.

Thus, thanks to the drilling machine and the work train comprising such a drilling machine, it becomes possible to easily install micro-piles of catenary pylons, along a railway track, while preserving the upper layer of ballast, and more generally the environment of the railway.

Claims (14)

Machine for drilling (1), under circulation of fluid, a ground (S) covered with a porous layer (P), for example a ballast layer, in which the machine (1) comprises: - a drive head (14) for rotating a drill rod (18), and - means for circulating a drilling fluid configured to inject a drilling fluid through the drill rod (18), in which the machine (1) is also configured to insert, through the porous layer (P), a protective tube (22) extending around the drill rod (18) and leaving an intermediate tubular space (29) between the drill rod (18) and the protection tube (22), and in which the machine (1) also comprises first means (30) for recovering the drilling fluid configured, during the insertion of the protection tube (22) through the porous layer (P), to suck, from the upper end of the protective tube (22), the drilling fluid coming from the drill rod (18) and present at the lower end of the tube protection (22). Machine (1) according to claim 1, also comprising second means for collecting (32) the drilling fluid, the second means for collecting (32) being configured to discharge the drilling fluid from the drill pipe (18) and protruding through the upper end of the protection tube (22) when the protection tube (22) is positioned through the porous layer (P). Machine (1) according to Claim 2, in which the first and second recovery means (30, 32) comprise a common pump and a connection means configured to connect the common pump to the first recovery means (30) during the insertion of the protection tube (22) through the porous layer (P), and to connect the common pump to the second recovery means (32) when the protection tube (22) is positioned through the porous layer (P). A machine according to claim 2 or 3, wherein the second collecting means is configured to be positioned at the upper end of the protection tube when the protection tube is positioned through the porous layer, the second collecting means including a reservoir , preferably in the form of a ring, into which the drilling fluid coming out of the protection tube is poured, and a peripheral seal, preferably circular, creating a seal between the reservoir and the outer wall of the protection tube. Machine (1) according to claim 4, in which the peripheral seal is an inflatable seal. Machine (1) according to one of claims 1 to 5, in which the drive head (14) is configured to also drive the protection tube (22) in rotation, preferably at the same time as the drill rod ( 18), when inserting the protective tube (22) through the porous layer (P). Machine (1) according to Claim 6, in which the driving head (14) comprises means (16) for mounting the drill rod (18), having a first determined diameter, and mounting means (20) of the protection tube (22), having a second determined diameter greater than the first determined diameter. Machine (1) according to Claim 7, in which the first means (30) for collecting the fluid are mounted on the drive head (14), for example above the mounting means (20) of the protection tube (22). ). Work train (34) comprising a machine (1) for drilling a ground (S) covered with a porous layer (P) according to one of claims 1 to 8. Work train (34) according to the preceding claim, comprising means for supplying a drilling fluid connected to the drive head (14), means for sucking the drilling fluid (36) configured to be connected to the recovery means (30, 32), and cement slurry supply means configured to be connected to the drive head (14). Work train (34) according to the preceding claim, also comprising a sludge recovery system, for example a settling tank (38), mounted downstream of the recovery means (30, 32). A method of drilling, under circulation of fluid, in a ground covered with a porous layer, for example a layer of ballast, in which: - A drill rod (18) is rotated, and - a drilling fluid is injected through the drill rod (18), preferably during the rotation of the drill rod (18), in which, during a first step,: - Inserting, through the porous layer, a protective tube (22) extending around the drill rod (18) and leaving an intermediate tubular space (29) between the drill rod (18) and the tube of protection (22), and - Is sucked from the upper end of the protection tube (22), the drilling fluid from the drill rod (18) and present at the lower end of the protection tube (22), during insertion of the protective tube (22) through the porous layer. Drilling method according to the preceding claim, wherein, during a second step, when the protective tube (22) is positioned through the porous layer, the protective tube is left in place. protection (22) and the drilling fluid from the drill rod (218) and exiting through the upper end of the protection tube (22) is discharged. A method according to claim 13, wherein during the first step, the protective tube (22) is driven together with a first part of the drill rod (18) equipped at its end with a tool (28) , then, during the second step, a second drill pipe part is assembled to the first drill pipe part and the two drill pipe parts (18) are rotated while injecting a drilling fluid through and by evacuating the fluid coming out through the upper end of the protection tube (22).

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