HK1213610B - Mixing tool for treating a portion of soil - Google Patents

Description

The Commission has already adopted a proposal for a directive.

The present invention relates to the treatment of soil sections in order to improve their mechanical, physical and/or chemical characteristics.

In particular, the present invention relates to a device for the treatment of a portion of soil (hereinafter referred to as a treatment device) by mixing such soil with another material, and a soil treatment process performed using this device.

The present invention relates in particular to a treatment device of the type comprising a rotating shaft extending along a main axis and having an upward facing upper end and a downward facing lower end, at least one deployable mixer attached to the rotating shaft near its lower end, and a longitudinal line for the injection of a fluid near the mixer.

The first two are:

The first step is to drill a tubular cavity in the soil, which is extracted from the hole before the treatment device is introduced. The tubular cavity may take the form of a simple drill hole. Another solution is to introduce a pipe into the soil to drill inside the pipe to make the cavity.the treatment device is inserted into the cavity and moved inside until its lower end enters the portion of soil to be treated. The mixer is then deployed, the shaft is rotated and a fluid is injected simultaneously into the portion of soil from the lower end of the shaft. The first stage of the tubular cavity construction involves the use of drilling tools and requires time which is not actually used for the actual soil treatment operation.The Commission has already taken a number of steps to ensure that the information provided by the Member States is accurate.

Purpose and summary of the invention

One purpose of the invention is to provide a device and treatment process that substantially overcomes the disadvantages mentioned above.

This is achieved with a treatment device of the above type by the fact that it also includes a drilling tool at the lower end of the shaft, an external tubular element extending along an axis parallel to the main axis of the rotating shaft, the rotating shaft being located inside the said tubular element, and a coupling system between the rotating shaft and the tubular element, the coupling system being, in one configuration, capable of solidarising the tubular and rotating shaft around the main axis, in at least one rotation configuration, and of solidarising the rotating element and the translation along the main axis, at least in one direction of translation and translation, and in the second, capable of freeing the movements referred to in the said translation and translation system, and of cutting the rotation and translation.

The device according to the invention is both a drilling device and a soil mixing device with one or more other materials.

The drill is provided directly at the lower end of the rotary shaft, so that a drill hole can be made as the device progresses.

It is recalled that drilling is necessary when the portion of soil to be treated is separated from the soil surface by a layer of soil which is not to be treated, particularly when the columns of treated soil are to be carried out under a layer of soil on which no intervention is to be carried out.

The coupling between the shaft and the tubular element allows the rotary and translational processing device to be moved in the ground by means of a single drive head.

When the coupling system is brought into its second configuration, the relative rotational and translational motions between the rotating shaft and the tubular element are released.

The treatment apparatus according to the invention is then adapted to perform an operation generally called soil mixing which consists of de-structuring the soil and then mixing the de-structured soil with a fluid to change the characteristics of the treated portion of soil.

It is particularly suitable for in situ cleaning operations, where the mixer deconstructs the soil and then mixes it with a chemical reagent.

During the treatment, a certain amount of material may tend to escape to the surface of the soil by the injection of a fluid into the soil.

According to one example of implementation, the deployable mixing tool shall comprise at least one deployable mixing arm fixed at the lower end of the rotating shaft and extending laterally relative to the longitudinal direction of the shaft, with the arm in an unfolded and retracted position, such that in the unfolded position the wingspan of the mixing tool is greater than the outer diameter of the tubular element to allow the treatment of the ground portion by rotation of the shaft, and in the retracted position the mixing tool is suitable for insertion into the tubular element.

According to one example, the mixing tool also has springs to cause the mixing arm to be unfolded out of the tubular element and to allow it to return to a retracted position when the lower part of the shaft is inserted into the tubular element.

The position deployed is then the natural position of the retractable arm, i.e. in the absence of any external stress, the arm extends laterally in relation to the longitudinal direction of the shaft by being detached from it by means of springs.

In this exposition, unless otherwise specified, an axial direction is a direction parallel to the main axis of the rotating shaft. In addition, a radial direction is a direction perpendicular to the main axis and intersecting that axis. Unless otherwise specified, the adjectives and adverbs axial, radial, axially and radially are used in reference to the axial and radial directions above. Similarly, an axial plane is a plane containing the main axis of the rotating shaft and a radial plane is a plane perpendicular to that axis. Similarly, an axial section is a section defined in an axial plane, and a radial section is a section defined in a radial plane.

Unless otherwise specified, the adjectives internal and external are used in reference to a radial direction such that the internal (i.e. radially internal) part or face of an element is closer to the main axis than the external (i.e. radially external) part or face of the same element.

In addition, unless otherwise specified, the adjectives upper and lower are used in reference to the direction of introduction of the device into the ground i.e. the direction of drilling, the tool being introduced from its lower end and removed from the ground from its upper end.

The terms upstream and downstream are also defined in relation to the direction of introduction of the device into the soil, i.e. the direction of drilling.

The coupling system is conveniently located near the lower end of the rotary shaft and the tubular element, and it is understood that part of the lower end of the rotary shaft is then coupled to part of the lower end of the tubular element when the coupling system is in its initial configuration.

For example, the coupling system may be located directly upstream of the mixing tool or, if there are several, upstream of the most upstream mixing tool along the main axis.

In particular, where the rotary shaft and the tubular element are respectively a rod and a tube train, the coupling system shall preferably be jointed by the rod end of the rod train and the tube end of the tube train.

As indicated above, the coupling system allows the tubing element and the rotary shaft to be joined together by rotation in at least one direction around the main axis of the rotary shaft and translation at least downwards along the axis of the rotary shaft.

As is well known to the professional, in order to achieve the desired drilling depth, the rotating shaft of a drilling tool is usually made up of a set of drill rods, i.e. a plurality of rods mounted successively one after the other.

Similarly, the outer tubular element is usually made up of a set of tubes, i.e. a plurality of tubes mounted successively one after the other.

For the mounting of the tube and rod trains, a clamping device is usually provided, also known as a guillotine . This device is used to immobilize a first drill rod or first drill tube introduced into the ground so that a second rod - respectively a second tube - can be screwed onto its upper end. Otherwise, the rotation of the second rod - respectively the second tube - would cause the simultaneous rotation of the first rod - respectively the first tube - inside the drill hole, preventing a good screwing between the two elements.

Where, as described above, the rotating shaft consists of several rods joined together and connected by threaded links, the coupling system shall generally be suitable for binding the tubular element and the rotating shaft together at least in the direction of screwing of the rods, so as to prevent their unscrewing when the tool is rotated.

Since tubes and rods are joined in rotation, the tubes are held in rotation when the rods are so. Therefore, when at least one rod and at least one tube (preferably the lower end rod of the rotating shaft and the lower end tube of the tubular element) are coupled by the coupling system, it is sufficient that the said rod be held in place by the clamping device so that a new rod and a new tube can be assembled.

Depending on the embodiment, the coupling system may also be provided at the upper end of the rotary shaft and the tubular structure.

After the soil portion has been treated with the mixer, the tubular element may be removed together with the rotary shaft or left in the soil.

In particular, where the tubular element must be capable of being removed together with the rotary shaft and the mixer tool, the coupling system may also be adapted to consolidate the tubular element and the rotary shaft in translation upstream along the main axis.

The coupling system can thus include means of cutting adapted to cooperate with the rotary shaft so that the rotary shaft and the tubular element are made solid in translation in the upstream direction regardless of the angular position of the rotary shaft.

For example, the means of stopping include a collarette formed on the inner face of the tubular element, the inner diameter of which is less than the maximum diameter of the rotating shaft downstream of the collarette.

According to an advantageous design of the invention, the coupling system is a bayonet system.

A bayonet system is defined as any attachment system with one or more hinges rotating into specially designed crests.

According to one example, the coupling system includes at least one ergot formed on the inner face of the tubular element and a corresponding number of cranes formed on the rotating shaft, each ergot being adapted to come into collision radially and axially against a cran.

Conversely, according to another example, the coupling system may comprise at least one ergot formed on the outer face of the rotating shaft and a corresponding number of ridges formed on the tubular element, each ergot being adapted to come in collision radially and axially against a ridge.

The crane may be a simple housing with a single axial buttress and a single radial buttress.

In some configurations the rotary shaft and the tubular element are not removed from the borehole together, so the coupling system is configured so that the rotary shaft and the tubular element are not in a joint upstream translation.

In other configurations, the coupling system may have other means of making the two elements in upstream translation compatible, in particular means of making this possible regardless of the angular position of the rotating shaft inside the tubular element, such as the collar mentioned above.

The cranes can also be housing with two axial buttes and one radial butte, in which case the coupling system is started (i.e. brought to its first configuration) by a simple pivoting movement to ensure that each ergot is introduced between the said buttes and the rotational coupling is obtained for a single direction of rotation, each ergot being removed from its respective cranes in the event of reverse rotation.

In one variant, the cranes can be L-shaped housing, respectively equipped with a return allowing the locking of the cranes in both directions of rotation. In this case, the system is started by a rotational movement immediately followed by a translation to bring the cranes into the said back part of the cranes.

It is understood that the coupling system may be formed by elements forming an integral part of the rotary shaft or the tubular element.

The coupling system may also include additional components cooperating with the rotary shaft or tubular element, in particular attached to either of these components.

Some parts of the coupling system may also be removable, as will be explained below.

According to one example, the treatment device shall comprise at least two mixing tools spaced axially along the main axis.

For example, different mixing tools may have different wings when in the deployed position.

For this purpose, for example, the mixing arms of the different mixing tools may have different lengths, including progressively increasing lengths along the main axis.

The invention also relates to a process for the treatment of a portion of soil in which a treatment device as defined above is provided, and which also includes at least the following steps: the rotary shaft and the rotary shaft are solidified by bringing the coupling system into its first configuration,the rotary shaft is lowered into the ground together with the tubing element to the soil portion to be treated,the rotary shaft and the tubing element are dissolved by bringing the coupling system into its second configuration,the rotary shaft is moved relative to the tubing element until the mixer tool is introduced into the soil portion to be treated,the mixer tool is deployed,and the rotary shaft is operated while a fluid is injected into the soil portion by the soil line,thus the soil portion of said fluid is mixed with the longitudinal fluid.

The injected fluid is for example a cleaning agent or a hydraulic binder.

In one embodiment of the invention, after treatment of the soil portion, the tubular element is extracted from the soil together with the rotary shaft.

In the treatment process according to the present invention, the operations of drilling and mixing the soil with another material are performed one directly after the other, without removal of the drilling tool in between or introduction of a separate mixing tool.

This is particularly advantageous when the portion of soil to be treated is located deep. Drilling methods which consist of digging rods into the soil as the drill is done to reach the desired depth, is tedious.

The two steps of drilling and mixing, carried out directly after each other using the same device, greatly reduce the time taken to process the rods and tubes, which are assembled once instead of twice when drilling and mixing are done with different tools.

In addition, the invention allows the assembly of rods and tubes at the same time, thanks to the coupling system, without the need to lower the rods first and then the rods, as was the case with earlier devices.

Several embodiments are described in this paper, but unless otherwise specified, the characteristics described in relation to one embodiment may be applied to another embodiment.

A brief description of the drawings

The invention will be better understood by reading the following description of a method of realization of the invention given as a non-limiting example, by reference to the attached drawings, on which: Figure 1 is a cut-out view of a processing device according to an embodiment of the invention, the coupling system being in its first configuration; Figure 2 is a cut-out view according to A-A of Figure 1; Figure 3 is a cut-out view according to B-B of Figure 1; Figures 4 and 5 are partial views, respectively, from the front and in perspective,Figures 6 and 7 are partial views of the tubular element, respectively in perspective and in cut, showing a complementary part of the coupling system; Figure 8 is a partial, split view of the coupling system; Figures 9A to 9F show the successive steps of a process for treating a portion of soil according to an example of implementation of the invention; Figures 10A to 10F illustrate the steps of assembly of a processing device according to an example of implementation of the invention, in which the rotary coupling is a train of rods and the tubular coupling is a train of 11A and 11B; Figures 11A and 11B illustrate a coupling system which can be used in a second treatment mode; Figures 11A and 12B show a more detailed description of the operation of the coupling system according to the invention.

Figure 1 is a cut-out view taken in a vertical plane showing a treatment device 10 of the invention, intended to treat a portion of soil defined from a depth P below the surface S of the soil.

In the example, device 10 is moved vertically for a vertical drill, and device 10 could also be used for a horizontal drill or for an inclined drill.

As shown in Figure 1, the processing device 10 comprises a longitudinal rotating shaft 20 of main axis X attached to rotating means not shown here but otherwise known, and an elongated hollow or external tubular element 30, including a tube, here coaxial to and encircling the rotating shaft 20.

The treatment device 10 described in the example is used in the implementation of a soil mixing process.

Soil mixing is a process of treating a portion of soil by mixing the de-structured soil with a fluid, such as a slurry or a reagent, to change its mechanical, physical and/or chemical properties.

In the example shown, the rotary shaft 20 has a drilling tool 24 at its lower end, e.g. a thread, to drill the ground to ensure the progression of the device 10.

In addition, a longitudinal pipe 22 passes through the rotating shaft for the injection of a fluid of the above type near the lower end of the shaft 28 20. In the example, the longitudinal pipe 22 passes through the drilling tool 24 and terminates at an injection hole 23 at the lower end of the tool.

The outer tubular element 30 also has cutting teeth 39 at its lower end 38.

The rotary shaft 20 may, when the ground portion to be treated ST is deep, consist of a succession of rods screwed together.

In the example, as will be shown below, both the rotary shaft 20 and the tubular element 30 are formed by joining several successive sections together, in particular by screwing.

At the lower end of the shaft 20 is a deployable mixing tool 40 comprising two similar arms 42 arranged on either side of a diameter of the shaft 20.

When the deployable tool 40 is in the tubular element 30 as shown in Figures 9A to 9C, the inner wall of the tubular element 30 acts on the arms 42 to bring them into a retracted position in which they extend along the lower end of the shaft 20. In this position, the entire length of each arm 42 runs along the shaft 20.

As shown in Figure 9D, both arms 42 are mounted pivoting on the lower end 28 of shaft 20 around axes orthogonal to the longitudinal direction X of shaft 20.

Spring means 44 (see Figure 1) are arranged between the rotating shaft 20 and each of the two arms 42 in such a way that these arms 42 have a natural tendency to unfold relative to the X-axis of the shaft 20 by the action of the springs 44 when they are outside the tubular element 30.

Preferably, in their deployed position, arms 42 form an open angle to the lower end of the shaft, as shown in Figure 9D.

Understandably, when the 42 arms are in the open position, they can deconstruct the ground when the 20 shaft is rotated.

As can be seen more clearly in Figure 8, the rotary shaft 20 has a generally circular section of constant diameter, and the tubular element 30 has a generally ring section of constant internal and external diameters.

The outer diameter of the rotating shaft 20 is less than the inner diameter of the tubular element 30. A ring passage 60, as shown in Figure 1, is thus maintained between the two elements 20, 30. As will be described in more detail below, this passage 60 allows the removal of drilling waste, i.e. the disintegrated soil mixture and drilling fluid from the drilling operation.

As shown in Figure 1, the device 10 of the invention comprises a disengageable coupling system 50 between the rotating shaft 20 and the tubular element 30.

When the rotary shaft 20 is housed inside the tubular element 30, i.e. when the mixing tool 40 is in the retracted position, the coupling system 50 shall be located upstream of the mixing tool 40.

Generally, the coupling system 50 consists of first elements fixed to or integral to the tubular element 30 and second elements fixed to or integral to the rotary shaft 20.

In the example, the coupling system 50 has a plurality of 54 shear points formed on the inner wall of the tubular element 30 suitable for cooperation with a corresponding number of 52 housing points formed on the outer wall of the rotating shaft.

Figures 6 and 7 illustrate a section 31 of the tubular element 30 on which the ergots 54 are formed. This section 31 is threaded at each end 31a, 31b for attachment to a tube 32, 33, head and foot, respectively, of the tubular element 30.

Each ergot 54 in the example is like an angular sector of an internal collarette formed on the inner wall of the tubular element 30.

In the example, the coupling system has three 54-pin joints on the inner wall of the tubular element, forming angles of 120° between them.

As shown in Figures 4, 5 and 8, housing 52 is formed in projection 53 formed at the periphery of the rotating shaft 20.

Figures 4 and 5 in particular illustrate a section 21 of the rotary shaft 20 with these protruding parts 53. This section 21 is threaded at each end 21a, 21b for attachment to a complementary section of the rotary shaft 20.

The outer radial face of the protruding parts 53 runs along the inner face of the tubular element 30.

Between the protruding parts 53, the rotary shaft 20 has grooves 51 extending longitudinally (i.e. in the main X direction). Each groove 51 corresponds to one of the housing 52 and is wide enough to allow an ergot 54 to slide inwards in the axial direction.

Figures 2 and 3 show that the depth of grooves 51 is chosen to ensure a sufficient flow section for drilling waste, the protruding parts 53 constituting a flow restriction for the waste which can be compensated, at least in part, by the grooves.

To accommodate a 54-ergot, each housing 52 is presented in the form of a notch, here of a complementary profile to that of the 54-ergot, made in the outer wall of the 53 protruding parts of the rotating shaft 20.

The coupling system is said to be in its first configuration when each ergot 54 is housed inside a housing 52.

In this configuration, if the rotating shaft 20 is rotated around the X-axis in the F1 direction, the 54 ergots each come in a bump against the vertical wall 52c of their housing 52 (defined in a considerably axial plane).

When, at the same time, the rotating shaft 20 is moved downwards, i.e. downwards on the various figures (direction marked X1), the ergots 54 come into collision against the upstream horizontal wall 52b of their housing 52 (defined in a radial plane).

When the coupling system 50 is in its initial configuration and when, as in Figures 9A and 9B, the rotary shaft 20 is rotated clockwise F1 and moved downstream (X1), i.e. to the depth of the ground, it carries the tubular element 30 with it.

The soil is disassembled by the drill tool 24 in the centre and by the drill teeth 39 at the periphery of the device 10. At the same time, a drilling fluid, usually water, is brought into the soil near the drill tool 24 by the longitudinal pipe 22.

The soil and drilling fluid mixture is carried up through the ring passage 60 formed between the tubular element 30 and the rotating shaft 20.

The translation and rotation movements are continued until the lower end of the tubular element 30 reaches the ground part to be treated ST, i.e. depth P.

In order to allow the mixer 40 to be introduced into the ground portion ST to be treated, the coupling system 50 is brought into its second position as shown in Figure 9C.

While the tubular element 30 is held in place by ground friction or a clamp provided for this purpose, the rotating shaft 20 is rotated in the anti-clockwise direction F2 by about 45° so that the ergot 54 is removed from its respective housing 52 and introduced into grooves 51.

As shown in Figure 9D, the rotary shaft 20 is then moved downstream (X1) until the 54 spindles leave the 51 grooves.

The coupling system is then in its second configuration, in which the rotary shaft 20 and the tubular element 30 are no longer coupled in rotation or translation.

The rotary shaft 20 may then be moved downstream (X1) until its lower end, and in particular the mixer tool 40, is extracted from the tubular element 30 and enters the ground portion to be treated ST.

When the arms 42 are deployed, the shaft 20 is rotated while fluid is injected into the ST portion of the ground from the lower end of the shaft 20, thus circumscribing the treated area to the above portion of the ground.

Once the soil portion has been treated to the desired depth, the rotary shaft 20 is raised (X2) until the mixer tool 40 in particular is again housed inside the tubular element 30.

The rotary shaft 20 is moved upwards along the main X-axis and rotated simultaneously.

Inevitably, the external tubular element being fixed, the grooves 51 of the rotary shaft 20 come in front of the 54 handles, which automatically fit in.

To extract the tubular element in conjunction with the rotary shaft, it would be relatively difficult (although possible with sufficient precision) to re-introduce each ergot 54 into one of the housing 52s to link the rotary shaft 20 and the tubular element 30 in translation upwards.

Therefore, as can be seen more particularly in Figure 8, an inner collar 56 is formed upstream of the 54 ergots on the inner wall of the tubular element 30 and this inner collar 56 has an inner diameter less than the diameter of the rotating shaft 20 on its downstream portion, in particular the diameter of the circle into which the protruding parts fit 53.

The collar 56 forms a continuous ring edge, which ensures translational locking of the rotary shaft 20 in relation to the tubular element 30 regardless of the angular position of the rotary shaft 20.

The collar 56 provides for easy removal of the tubular element 30 simultaneously with the rotating shaft 20.

Figures 10A to 10F illustrate the assembly, in advance, of a device 10 of the invention in which the rotating shaft 20 and the tubular element 30 are respectively a rod train and a tube train.

In Figure 10A, a lower 201 (or first) rod of the rotary shaft 20 is attached to a displacement device with a rotation head 70 and surrounded by a lower 301 (or first) tube of the tubular element 30.

A coupling system 50 of the type described above is formed between the first rod 201 and the first tube 301 and brought into its first configuration, in which the first rod 201 and the first tube 301 are coupled in rotation in the direction of the rods' screw, which will also, for obvious reasons, correspond to the direction of rotation of the device during drilling operations.

As in the example described above, a drill tool 24 is provided at the lower end of the first 201 rod, and a mixing tool 40 is provided between the coupling system 50 and the drill tool 24.

Two guillotines, respectively upstream 81 and downstream 82, are arranged at the right of the location intended for the drilling, and therefore of the portion of soil to be treated.

In a first step, as shown in Figure 10B, the assembly is rotated by the rotation head 70 and moved downwards so as to penetrate the ground until the first tube 301 is facing the downward guillotine 82 and the portion of the first rod 201 leading out of the tube 301 is facing the upward guillotine 81.

The downward guillotine 82 is tightly wrapped around the first tube 301.

As the first tube 301 and the first rod 201 are rotated by means of the coupling system 50, the first rod 201 shall be held in the normal direction of rotation of the device.

A rotation of the 201 rod in the opposite direction would, on the contrary, disengage the coupling with the first tube 301.

To unwind the rotation head 70, as shown in Figure 10B, the first 201 rod is therefore in the same way held in place by the upstream guillotine 81.

Once un screwed, the rotary head 70 is raised and the upstream guillotine 81 is loosened (see Figure 10C) to allow a second rod 202 and a second tube 302 to be screwed on the first rod 201 and the first tube 301, respectively (see Figure 10D).

The assembly is once again rotated and inserted into the ground, as shown in Figure 10E. Once again, the two guillotines 81 and 82 are tightened.

Rotorhead 70 is unscrewed.

As shown in Figure 10F, the upstream guillotine 81 is again loosened and the rotation head 70 removed to allow screwing on the second rod 201 and second tube 301 of a third rod and a third tube (not shown) respectively.

All the above steps are repeated as many times as necessary to achieve sufficient depth of drilling.

A processing device 100 according to a second embodiment of the present invention is shown in Figures 11A, 11B and 12.

The mixing tool and the drilling tool remain in the same position as in the previous embodiment and their respective structures remain the same, so they are not represented or described again.

This method differs essentially from the previous one in that the coupling system 150 is located near the upper end of the device 100.

It is, however, as before, a bayonet system.

The coupling system 150 comprises a plurality of 154 (up to three) sheaves, this time formed on the outer wall of the rotating shaft 120, and a corresponding number of 152 housing units formed in the wall of the tubular element 130.

As the coupling system 150 is located at the upper end of the device, it is necessary that it can be dismantled in cases where the rotating shaft 120 and the tubular element 130 are respectively a rod train and a tube train.

In the example, the coupling system 150 therefore comprises two parts 158, 159 which are fixed removably at the upper end of the tubular element 130 and at the upper end of the rotating shaft 120, respectively.

A first piece 158, in the form of a socket, is fitted to cooperate with the upper end of a tube of the tubular element 130 by its threaded end 158a (see Figure 11A).

A second part 159, which is substantially cylindrical, is fitted to cooperate with the upper end of a rod of the rotary shaft 20 by its threaded end 159a (see Figure 11B).

It is understood that the three 154 ergots are suitable for sliding into the corresponding 152 slots formed on the first 158 piece.

In the example in Figure 11A, each slot 152 has a first section 155a extending longitudinally in the direction of the X-axis, a second section 155b extending transversely through the first section 155a, and a return 155c.

According to the same principle as described above in connection with the first embodiment, the coupling system 150 is said to be in its first configuration when each ergot 154 is positioned in a corresponding 155c return formed on the tubular element 130.

In this first configuration, the rotary shaft 120 and the tubular element 130 are coupled in translation downwards and in rotation clockwise F1 (see Figure 12).

Claims (17)

1. A device (10, 100) for treating a portion of soil (ST), comprising:

   a rotary shaft (20, 120) extending along a main axis (X) and presenting a top end (26) pointing upstream and a bottom end (28) pointing downstream;

   · at least one deployable mixer tool (40) fastened to the rotary shaft (20, 120) in the vicinity of its bottom end (28); and

   · a longitudinal pipe (22) for injecting a fluid into the proximity of the bottom end of the rotary shaft (20, 120);

   characterized in that it further comprises:

   · a boring tool (24) situated at the bottom end of the shaft;

   · an outer tubular element (30, 130) extending along an axis parallel to the main axis (X) of the rotary shaft (20, 120), the rotary shaft (20, 120) being arranged inside said tubular element (30, 130); and

   · a coupling system (50, 150) between the rotary shaft (20, 120) and the tubular element (30, 130), said coupling system (50, 150) being, in a first configuration, capable of constraining the tubular element (30, 130) and the rotary shaft (20, 120) to move together in rotation about the main axis (X), in at least one direction of rotation, and for constraining the tubular element (30, 130) and the rotary shaft (20, 120) to move together in translation along the main axis (X), at least in the downstream direction, and said coupling system (50, 150) being, in a second configuration, capable of releasing said movement in rotation and in translation.
2. A treatment device (10, 100) according to claim 1, wherein the mixer tool (40) is housed in the tubular element (30, 130) when the coupling system (50, 150) is in its first configuration.
3. A treatment device (10, 100) according to claim 1 or claim 2, wherein the mixer tool (40) is adapted to be extracted from the tubular element (30, 130) and to be introduced into a portion of soil to be treated (ST) when the coupling system (50, 150) is in its second configuration.
4. A treatment device (10, 100) according to any one of claims 1 to 3, wherein the coupling system (50, 150) is a bayonet system.
5. A treatment device (10, 100) according to claim 4, wherein the coupling system (50) includes at least one lug (54) formed on the inside face of the tubular element (30) and a corresponding number of catches (52) formed on the rotary shaft (20), each lug (54) being adapted to come into abutment radially and axially against a catch (52).
6. A treatment device (10, 100) according to any one of claims 1 to 5, wherein the deployable mixer tool (40) comprises at least one deployable mixer arm (42) fastened to the bottom end (28) of the rotary shaft (20, 120) and extending laterally relative to the main direction (X) of the shaft (20, 120), said arm (42) presenting a deployed position and a retracted position, such that in the deployed position the span of the mixer tool (40) is greater than the outside diameter of the tubular element (30, 130) to enable the portion of soil (ST) to be treated by rotating the shaft (20, 120), and in the retracted position, the mixer tool (40) is suitable for being inserted inside the tubular element (30, 130).
7. A treatment device (10, 100) according to claim 6, wherein the mixer tool (40) further includes spring means (44) suitable for causing the mixer arm (42) to deploy out from the tubular element (30) and for enabling it to return into its retracted position while the bottom portion (28) of the shaft (20, 120) is being inserted in the tubular element (30, 130).
8. A treatment device (10, 100) according to any one of claims 1 to 7, wherein the coupling system (50, 150) is suitable for constraining the tubular element (30, 130) and the rotary shaft (20, 120) to move together in rotation about the main axis (X) in both directions of rotation.
9. A treatment device (10, 100) according to any one of claims 1 to 8, wherein the coupling system (50, 150) is also adapted to constrain the tubular element (30, 130) and the rotary shaft (20, 120) to move together in translation along the main axis (X) in the upstream direction.
10. A treatment device (10, 100) according to claim 9, wherein the coupling system (50) further includes abutment means (56) adapted to co-operate with the rotary shaft (20) so that the rotary shaft (20) and the tubular element (30) are constrained to move together in translation in the upstream direction regardless of the angular position of the rotary shaft (20).
11. A treatment device (10, 100) according to claim 10, wherein the abutment means (56) comprise a collar formed on the inside face of the tubular element (30), the inside diameter of said collar (56) being smaller than the maximum diameter of the rotary shaft (20) on the portion of said shaft (20) that is situated downstream from said collar (56).
12. A treatment device (10, 100) according to any one of claims 1 to 11, including at least two mixer devices (40) that are spaced apart axially along the main axis (X).
13. A treatment device (10, 100) according to any one of claims 1 to 12, wherein the coupling system (50) is provided in the vicinity of the bottom end (28) of the rotary shaft (20) and of the tubular element (30).
14. A method of treating a portion of soil, wherein a treatment device (10, 100) according to any one of claims 1 to 13 is provided, said method further comprising at least the following steps:

    · constraining the tubular element (30, 130) and the rotary shaft (20, 120) to move together by bringing the coupling system (50, 150) into its first configuration;

    · lowering the rotary shaft (20, 120) into the soil (S) together with the tubular element (30, 130) until reaching the portion of soil to be treated (ST);

    · unconstraining the rotary shaft (20, 120) and the tubular element (30, 130) by bringing the coupling system (50, 150) into its second configuration;

    moving the rotary shaft (20, 120) relative to the tubular element (30, 130) until the mixer tool (40) is inserted into the portion of soil for treatment (ST);

    · deploying the mixer tool (40); and

    · rotating the shaft (20, 120) while injecting a fluid into the portion of soil via the longitudinal pipe (22), whereby the portion of soil (ST) is mixed with said fluid.
15. A method of treating a portion of soil according to claim 14, wherein, after the portion of soil (ST) has been treated, the tubular element (30, 130) is extracted from the soil together with the rotary shaft (20, 120).
16. A method of treating a portion of soil according to claim 14 or claim 15, wherein the injected fluid is a depolluting agent.
17. A method of treating a portion of soil according to claim 14 or claim 15, wherein the injected fluid is a hydraulic binder.