EP3887603B1 - Method for treating soil - Google Patents

Description

Technical area

The present invention relates to the field of treatment of a floor in order to modify its physical properties such as, for example, waterproofing or solidity. The invention relates more precisely to a process for treating such soil.

Prior art

It is known to inject injection fluids such as sealing or stiffening products into a soil. In particular, when a stiffening product is injected into a ground, it fills the roughness of said ground or the cracks present in the case of rocky ground, in order to consolidate the latter.

To treat soil at depth, methods are known in which a drilling is carried out and then the injection fluid is injected from an injection zone inside the drilling, towards the side wall of said drilling. The injection fluid then spreads into the soil, so that a portion of soil is then treated. However, in the presence of heavily fractured or very unstable ground, it may be necessary to reinforce the side wall of the borehole. Also, to prevent this wall from collapsing and blocking the borehole, a tube is traditionally inserted into the borehole, above the injection zone, at the level of the unstable soil portions.

This tube makes it possible to maintain the side wall of the borehole and to carry out soil treatment independently of the state of the soil at the different depths considered along the borehole. When the fluid injection is completed, the tube is extracted from the borehole.

A disadvantage of this type of process is that during injection, the injection fluid is projected partly towards the tube so that it covers said tube and infiltrates between the tube and the wall of the borehole. The injection fluid increases the friction between the tube and the ground, which makes it very difficult to move or extract the tube from the borehole. In the worst case, the injection fluid solidifies so that the tube is caught in the injection fluid, especially when it is a stiffening product. The tube is then blocked in the borehole by the injection fluid, in which case it must be left in the borehole, which is not desirable.

It is known for example from the document FR2529612A1 to use a shutter placed between the bottom of the borehole and the tube, in order to delimit an injection zone. The obturator prevents the projection of the injection fluid directly onto the tube and therefore limits the risk of the tube blocking in the drilling.

However, we understand that once injected, the injection fluid percolates and spreads step by step in the ground so that it bypasses the shutter. The injection fluid, possibly mixed with soil particles, then forms cuttings which finally infiltrate between the tube and the side wall of the borehole. The shutter is therefore insufficient to overcome the blockage of the tube in the drilling, caused by the injection fluid.

Presentation of the invention

An aim of the present invention is to propose a method of treating soil which remedies the aforementioned problems.

• on fournit un tube ayant une extrémité distale ;
• on réalise un forage dans le sol, le forage ayant un fond, une paroi latérale, une profondeur de forage et s'étendant selon une direction de forage;
• on positionne le tube dans le forage à une première profondeur prédéterminée inférieure à la profondeur de forage ;
• on introduit au moins un premier élément d'obturation dans le forage à une deuxième profondeur prédéterminée comprise entre la première profondeur prédéterminée et la profondeur de forage, de sorte qu'il s'étend entre l'extrémité distale du tube et le fond du forage, ledit au moins un premier élément d'obturation étant configuré pour obturer le forage afin de définir une zone d'injection située entre ledit au moins un premier élément d'obturation, le fond du forage et la paroi latérale du forage ; puis
• on injecte un fluide d'injection dans la zone d'injection tout en réalisant une étape d'évacuation des déblais situés entre le tube et la paroi latérale du forage, l'étape d'évacuation des déblais comprenant le nettoyage de la surface extérieure du tube, l'étape de nettoyage de la surface extérieure du tube comprenant l'injection d'un fluide de lavage autour du tube.

To do this, the invention relates to a method of treating soil comprising the following steps:

• providing a tube having a distal end;
• drilling is carried out in the ground, the drilling having a bottom, a side wall, a drilling depth and extending in a drilling direction;
• the tube is positioned in the borehole at a first predetermined depth less than the drilling depth;
• at least one first sealing element is introduced into the borehole at a second predetermined depth between the first predetermined depth and the drilling depth, so that it extends between the distal end of the tube and the bottom of the borehole , said at least one first shutter element being configured to close the borehole in order to define an injection zone located between said at least one first shutter element, the bottom of the borehole and the side wall of the borehole; Then
• an injection fluid is injected into the injection zone while carrying out a step of evacuating the cuttings located between the tube and the side wall of the drilling, the step of evacuating the cuttings comprising cleaning the exterior surface of the tube, the step of cleaning the outer surface of the tube comprising the injection of a washing fluid around the tube.

The method according to the invention makes it possible to treat one or more selected portions of soil using the injection fluid having physical properties adapted to the desired treatment.

Drilling is preferably carried out using a drilling machine comprising a ground cutting tool. It has substantially the shape of a cylinder having a diameter. The drilling advantageously includes a edge in the upper part, opening out of the borehole. The drilling is preferably carried out so as to pass through the portion of soil to be treated, and the drilling depth is chosen so that the portion of soil to be treated is located between the bottom and the edge of the drilling.

The drilling direction may be substantially vertical or inclined relative to the vertical.

The tube preferably has the shape of a cylinder having a diameter slightly smaller than the diameter of the borehole, so that it can easily be introduced into said borehole. It preferably has a length less than the drilling depth.

The tube is preferably configured to be placed in the borehole facing a portion of unstable or fractured soil, likely to collapse. It then makes it possible to maintain the side wall of the borehole at a height equal to the first predetermined depth, in order to prevent said side wall from collapsing.

The distal end of the tube is configured to face the bottom of the borehole when the tube is inserted into the borehole. The first predetermined depth is the depth to which said distal end of the tube extends when placed in the borehole.

Additionally, the tube preferably includes a proximal end configured to extend outside the borehole.

Preferably, the drilling tube can be moved in the drilling so as to successively support the side wall of the drilling at different depths. In particular, the tube can be moved in a direction opposite to the bottom of the borehole, so as to gradually increase the height of the injection zone.

The injection fluid can be injected successively at different depths in order to treat a plurality of portions of soil.

Without departing from the scope of the invention, the method may comprise the supply and positioning of a plurality of tubes at different depths in order to consolidate the side wall of the borehole at said different depths.

The injection fluid is injected from the injection zone, inside the borehole, preferably towards the side wall of the borehole.

The first shutter element advantageously has a cylindrical shape and a diameter substantially equal to the diameter of the borehole. When introduced into the borehole, it preferably forms a barrier airtight to prevent the projection of fluid outside the projection zone and therefore directly towards the tube.

However, we understand that the injection fluid risks infiltrating into the ground and spreading there by percolation. Also, the injection fluid, possibly mixed with soil particles, risks bypassing the first sealing element and coming into contact with the drilling tube, via the soil. The injection fluid, possibly mixed with the soil particles, then forms cuttings infiltrating between the tube and the side wall of the borehole. These cuttings disrupt the movement and extraction of the tube in relation to drilling.

The cuttings evacuation step then makes it possible to remove all or part of these cuttings and therefore the injection fluid in contact with the tube. An advantage is to prevent the tube from being caught in the injection fluid, particularly if it is a stiffening product such as cement. The cuttings evacuation step also makes it possible to lighten the tube and reduce the friction between the tube and the side wall of the drilling, generated by said cuttings.

The cuttings evacuation step therefore facilitates the movement of the tube in the drilling as well as the extraction of said tube out of the drilling. The cuttings are evacuated outside the borehole and can be treated and reused later.

In a non-limiting manner, the evacuation of the debris can be carried out from the start of the injection of the injection fluid or in a delayed manner. The cuttings evacuation step is preferably carried out before solidification of the injection fluid in contact with the tube, particularly when it is a grout, for example cement.

According to the invention, the step of removing the debris comprises cleaning the exterior surface of the tube. An advantage is to remove all or part of the injection fluid having infiltrated between the side wall of the borehole and said exterior surface of the tube. Cleaning the outer surface of the tube makes it possible to remove and evacuate the cuttings until the outer surface of the tube is significantly lightened with injection fluid and cuttings. This further reduces friction between the tube and said side wall of the borehole so as to further facilitate the movement or extraction of the tube from the borehole.

We preferably clean the part of the tube which is placed in the ground.

In a non-limiting manner, the step of cleaning the exterior surface of the tube can be carried out by suction of the cuttings, by rubbing the exterior surface of the tube or by any other technique making it possible to reduce the quantity of debris covering said exterior surface of the tube.

Advantageously, the step of cleaning the exterior surface of the tube comprises rotating said tube around the drilling direction. This rotation makes it possible to avoid the solidification of the injection fluid in contact with the tube and therefore the blocking of the tube in the drilling. In addition, rotating the tube tends to move the debris towards the ends of the tube and therefore clean the exterior surface of the tube. Furthermore, rotating the tube generates friction between the outer surface of the tube and the side wall of the borehole making it possible to remove the cuttings covering said outer surface of the tube.

The speed of rotation of the tube is preferably relatively slow, of the order of a few revolutions per minute. The rotation speed of the tube can advantageously be controlled, monitored and recorded.

Tube rotation can be manually controlled by an operator or triggered automatically in response to a trigger signal. Preferably, the step of rotating the tube is carried out using a displacement device configured to cause the tube to rotate around the drilling direction.

In a non-limiting manner, the movement device can also be configured to move the tube in translation, in particular according to the drilling direction. This makes it possible to easily introduce the tube into the borehole and to easily adjust the first determined depth to which the tube extends in the borehole, while rotating said tube.

The displacement device is advantageously arranged outside the borehole and cooperates with the tube so that the proximal end of the tube also extends outside the borehole. The torque applied to the tube when it rotates can advantageously be controlled.

Advantageously, the distal end of the tube carries a cutting member, and the step of drilling the ground is carried out using the tube moved in the ground in the drilling direction up to the drilling depth. An advantage is to carry out the drilling and the introduction of the tube into the drilling in a single step. This eliminates the need for a drilling tool separate from the tube and a step of introducing the tube subsequent to drilling. This saves time and reduces the number of tools necessary for implementing the treatment process.

Advantageously, the diameter of the tube is substantially equal to the diameter of the borehole, whereby the tube substantially matches the shape of the borehole. An advantage is to minimize the subsidence of the side wall of the borehole towards the interior of the borehole. The risk of collapse of the side wall of the borehole is further reduced.

Preferably, the method comprises the steps according to which a torque sensor is provided, the resistant torque applied to the tube is measured using the torque sensor, and a possible presence of cuttings in contact with the tube is detected, thanks to the torque resistance measured.

The presence of cuttings, and in particular injection fluid, in contact with the tube induces friction opposing the rotation of said tube. This generates a resistant torque opposing the driving of the rotating tube. Also, by detecting the presence of such a resistant torque, or a resistant torque greater than a predetermined threshold, applied to the tube, using the torque sensor, we can deduce the presence of cuttings disturbing the rotation of the tube .

An advantage is to be able to trigger the rotation of the tube only in the presence of debris in contact with said tube. This reduces wear on the tube as well as the fuel costs required to rotate it.

Preferably, said at least one first shutter element has a retracted position in which it can be moved in the borehole and an deployed position in which it cooperates with the side wall of the borehole to seal the borehole in order to define said zone of injection. An advantage is to be able to easily introduce the sealing element into the borehole. It is preferably introduced into the borehole in the retracted position, moved to the second predetermined depth then placed in the deployed position.

Another advantage is to be able to adjust the position of the first shutter element at any time, for example when it is necessary to successively treat different portions of soil at different depths. In this case, the first shutter element is placed in the retracted position, moved, then placed again in the deployed position. This also makes it possible to adjust the dimensions of the injection zone.

Advantageously, said at least one first shutter element is inflatable. In the retracted position, the sealing element is deflated while it is inflated when placed in the deployed position. An advantage is to be able to easily and quickly place the first obturation element in the retracted position or in the deployed position. Another advantage is that the first sealing element matches the side wall of the borehole more effectively once inflated, which reduces the risk of leakage and therefore infiltration of injection fluid between said side wall of the borehole and said first element. shutter.

In a non-limiting manner, the sealing element can be connected to an inflation member placed outside the borehole, allowing it to be inflated or deflated from outside the borehole.

Preferably, the introduction of said at least one first shutter element into the borehole comprises the introduction of said first shutter element, in the retracted position, into the tube and the movement of said first shutter element along the tube until at the second predetermined depth. The tube is therefore placed in the borehole before introducing and positioning the first sealing element. An advantage is to reduce the risk that said first sealing element is damaged due to a collapse of the side wall of the borehole. In addition, the tube makes it possible to guide the movement of the first shutter element in the drilling. The transverse dimensions of the first shutter element in the retracted position are less than the diameter of the tube.

Advantageously, the injection of the injection fluid is carried out using an injection device comprising an injection channel extending inside the tube and opening into the injection zone.

The injection channel is preferably connected to an injection fluid supply source located outside the borehole and makes it possible to bring the injection fluid from outside the borehole into the injection zone. The tube helps protect the injection channel against the collapse of the side wall of the borehole and reduces the risk of damage to said injection channel.

Preferably, the injection device comprises an injection nozzle disposed at the distal end of the injection channel and configured to be introduced into the injection zone, at a desired depth. The injection device is preferably moved along the borehole, in the injection zone, in order to treat a plurality of portions of soil at different depths.

Advantageously, the injection channel passes through said at least one first sealing element, whereby the injection fluid can be easily injected into the injection zone, between the first element shutter and the bottom of the borehole. The first sealing element therefore extends radially around the injection channel. When it is in the deployed position, the first shutter element substantially matches the shape of the injection channel, so as to reduce the risk of injection fluid infiltration between said first shutter element and said injection channel. injection.

Preferably, the first sealing element and the injection channel are introduced simultaneously into the borehole.

Preferably, the treatment method comprises a step according to which a second sealing element is introduced into the drilling at a third predetermined depth between the second predetermined depth and the drilling depth, so that it is between said at least a first sealing element and the bottom of the borehole, said second sealing element being configured to seal the borehole so that the injection zone extends between the first sealing element, the second sealing element and the side wall of the borehole.

The second sealing element prevents the injection of fluid directly between the bottom of the borehole and said second sealing element. An advantage is to delimit an injection zone of reduced height, considered according to the drilling direction. This makes it possible to treat a small and localized portion of soil. This avoids treating the soil all the way to the bottom of the borehole, if this is not necessary.

The second shutter element is preferably identical to the first shutter element. It is preferably inflatable and can be easily moved inside the borehole. Advantageously, the first and second shutter elements are fixed relative to each other so that the distance separating them remains constant and they can be moved together.

According to a non-limiting variant, the first and second shutter elements can be movable relative to each other. Also, in this variant, the height of the injection zone, considered according to the drilling direction, can be adjusted by moving the first and second shutter elements relative to each other, in order to modify the distance separating them.

Advantageously, the first and second sealing elements are introduced into the borehole at the same time. They are preferably both introduced into the tube in the retracted position, positioned in the borehole then placed in the deployed position.

Preferably, the injection fluid is chosen from a sealing product and a hardenable mud configured to consolidate the soil. The waterproofing product is particularly suitable when it is necessary to treat the ground to reduce water infiltration, for example under a dam. The use of a hardenable mud is particularly suitable for reinforcing the ground, when it is intended to support a building.

Alternatively, the injection fluid may be a grout or a concrete.

The injection fluid is preferably a fluid capable of infiltrating and percolating in porous soil, in order to spread there to treat an extended portion of soil around the borehole.

According to the invention, the step of cleaning the exterior surface of the tube comprises the injection of a washing fluid around the tube. An advantage is to effectively eliminate the cuttings having infiltrated between the drilling tube and the side wall of the drilling. The washing fluid carries away the cuttings between the tube and the side wall of the borehole and effectively cleans the outer surface of the tube. The risk of the tube getting stuck in the borehole is further reduced.

The washing fluid is advantageously projected evenly over the entire exterior surface of the tube. The injection of the washing fluid can be triggered as soon as the injection fluid is injected or in a delayed manner.

The step of cleaning the outer surface of the tube includes injecting the washing fluid or rotating the tube simultaneously with the injection of the washing fluid.

Preferably, the washing fluid is injected if the presence of cuttings in contact with the tube is detected using the torque sensor. An advantage is not to inject the washing fluid unnecessarily, in the absence of debris in contact with the tube. This reduces the amount of washing fluid needed and therefore the costs associated with cleaning the tube.

In a non-limiting manner, the injection of the washing fluid can be triggered when the quantity of cuttings detected in contact with the tube is greater than a predetermined threshold.

Advantageously, the washing fluid is injected through the distal end of the tube towards the bottom of the borehole. The tube is used as a conduit, such that fluid is introduced into the tube from its proximal end, then brought to the distal end of the tube and finally injected into the borehole through its distal end. The washing fluid fills then an upper part of the borehole located above the first sealing element and infiltrates between the exterior surface of the tube and the side wall of the borehole. The cuttings present in this upper part of the drilling then mix with the washing fluid and are carried towards the upper end of the drilling. The washing fluid then flushes the cuttings out of the borehole. This step allows the debris to be evacuated and the exterior surface of the tube to be effectively cleaned.

Preferably, the step of injecting a washing fluid is carried out using an injection head configured to inject the washing fluid into the tube, the injection head comprising a fixed part and a pivoting part, the pivoting part being configured to cooperate with the tube. The injection head is preferably configured to be connected to a washing fluid supply source.

The injection head can advantageously be removably mounted at the proximal end of the tube, so that the pivoting part cooperates with said proximal end of the tube. The fixed part can be integral with a device for moving the tube.

The injection head advantageously comprises a hole passing through the fixed and pivoting parts in the drilling direction. The hole therefore passes through the injection head, preferably right through. Said hole is configured to receive an injection channel. Furthermore, the first sealing element can advantageously be introduced through said through hole and guided into the borehole via the injection head then the tube.

The injection head advantageously comprises a side wall in which an orifice is provided. Said orifice passes through the fixed part and the pivoting part and opens into the through hole. Said orifice is configured to be connected to a washing fluid supply source. Also, the fluid is injected into the hole passing through the injection head, via the orifice made in its side wall. The washing fluid is then guided into the tube. The washing fluid flows advantageously between the tube and the injection channel.

• un tube ayant une extrémité distale, ledit tube étant configuré pour être positionné dans le forage à une première profondeur prédéterminée inférieure à la profondeur de forage ;
• au moins un premier élément d'obturation configuré pour être introduit dans le forage à une deuxième profondeur prédéterminée comprise entre la première profondeur prédéterminée et la profondeur de forage, ledit au moins un premier élément d'obturation étant configuré pour obturer le forage afin de définir une zone d'injection située entre ledit au moins un premier élément d'obturation, le fond du forage et la paroi latérale du forage ;
• un dispositif d'injection configuré pour injecter un fluide d'injection dans le forage ; et
• un dispositif d'évacuation des déblais configuré pour évacuer les déblais situés entre le tube et la paroi latérale du forage lors de l'injection du fluide d'injection dans le forage, par nettoyage de la surface extérieure du tube en injectant un fluide de lavage autour du tube.

The invention also relates to a device for treating soil in which a borehole is made having a bottom, a side wall, a drilling depth and extending in a drilling direction, the treatment device comprising:

• a tube having a distal end, said tube being configured to be positioned in the borehole at a first predetermined depth less than the drilling depth;
• at least one first shutter element configured to be introduced into the borehole at a second predetermined depth between the first predetermined depth and the drilling depth, said at least one first shutter element being configured to seal the borehole in order to define an injection zone located between said at least one first sealing element, the bottom of the borehole and the side wall of the borehole;
• an injection device configured to inject an injection fluid into the borehole; And
• a cuttings evacuation device configured to evacuate the cuttings located between the tube and the side wall of the borehole when injecting the injection fluid into the borehole, by cleaning the outer surface of the tube by injecting a washing fluid around the tube.

Preferably, the cuttings evacuation device comprises a displacement device configured to rotate the tube around the drilling direction.

Advantageously, the debris evacuation device comprises an injection head for injecting a washing fluid around the tube.

Brief description of the drawings

• [Fig. 1]La figure 1 illustre une première étape d'un procédé de traitement d'un sol conforme à l'invention;
• [Fig. 2]La figure 2 illustre une deuxième étape du procédé de traitement d'un sol conforme à l'invention;
• [Fig. 3]La figure 3 illustre une troisième étape du procédé de traitement d'un sol conforme à l'invention;
• [Fig. 4]La figure 4 illustre une quatrième étape du procédé de traitement d'un sol conforme à l'invention;
• [Fig. 5]la figure 5 illustre une cinquième étape du procédé de traitement d'un sol conforme à l'invention;
• [Fig. 6]La figure 6 illustre une sixième étape du procédé de traitement d'un sol conforme à l'invention;
• [Fig. 7]La figure 7 illustre une septième étape du procédé de traitement d'un sol conforme à l'invention;
• [Fig. 8]La figure 8 illustre une huitième étape du procédé de traitement d'un sol conforme à l'invention;
• [Fig. 9]La figure 9 illustre une neuvième étape du procédé de traitement d'un sol conforme à l'invention;
• [Fig. 10]La figure 10 illustre une variante de la neuvième étape du procédé de traitement d'un sol de la figure 9 ;
• [Fig. 11]La figure 11 illustre le sol traité suite à l'étape illustrée en figure 10 ;
• [Fig. 12]La figure 12 illustre une tête d'injection d'un dispositif de traitement selon l'invention ; et
• [Fig. 13]La figure 13 illustre une vue en coupe de la tête d'injection de la figure 12 .

The invention will be better understood on reading the following description of embodiments of the invention given by way of non-limiting examples, with reference to the appended drawings, in which:

• [ Fig. 1 ]There figure 1 illustrates a first step of a method of treating soil according to the invention;
• [ Fig. 2 ]There figure 2 illustrates a second step of the method of treating a soil according to the invention;
• [ Fig. 3 ]There Figure 3 illustrates a third step of the method of treating a soil according to the invention;
• [ Fig. 4 ]There figure 4 illustrates a fourth step of the method of treating a soil according to the invention;
• [ Fig. 5 ]there Figure 5 illustrates a fifth step of the method of treating a soil according to the invention;
• [ Fig. 6 ]There Figure 6 illustrates a sixth step of the method of treating a soil according to the invention;
• [ Fig. 7 ]There Figure 7 illustrates a seventh step of the method of treating a soil according to the invention;
• [ Fig. 8 ]There figure 8 illustrates an eighth step of the method of treating a soil according to the invention;
• [ Fig. 9 ]There Figure 9 illustrates a ninth step of the method of treating a soil according to the invention;
• [ Fig. 10 ]There Figure 10 illustrates a variant of the ninth step of the process of treating a soil of the Figure 9 ;
• [ Fig. 11 ]There Figure 11 illustrates the soil treated following the step illustrated in Figure 10 ;
• [ Fig. 12 ]There Figure 12 illustrates an injection head of a treatment device according to the invention; And
• [ Fig. 13 ]There Figure 13 illustrates a sectional view of the injection head of the Figure 12 .

Description of embodiments

The invention relates to a method of treating soil. This process makes it possible to modify the physical properties of a portion of soil to be treated, by injecting an injection fluid.

With the help of figures 1 to 9 , we will describe a first embodiment of the method, in accordance with the present invention, for treating a first portion Z1 of a soil S and a second portion Z2 of said soil. In this example, the ground S notably comprises a first unstable part S1 and a second unstable part S2 extending above the first unstable part S1.

In accordance with the method according to the invention, a hollow and cylindrical tube 10 is provided, having a proximal end 10a and a distal end 10b, opposite the distal end 10a. In this example, the distal end 10b corresponds to the lower end of the tube and the proximal end 10a corresponds to the upper end of the tube 10. The tube 10 comprises at its distal end 10b a plurality of cutting teeth 12 forming a cutting member for cutting the ground S.

In a non-limiting manner, we also provide a drilling machine 14 provided with a mast 16 and a movement device 18. In this non-limiting example, the movement device 18 is mounted sliding along the mast 16. The tube 10 cooperates with the displacement device 18 so that said displacement device 18 is configured to drive said tube 10 in rotation.

The speed of rotation of the tube 10 can advantageously be controlled and adjusted. Furthermore, the displacement device 18 also comprises a torque sensor 19, making it possible to measure a resistant torque applied to the tube 10, opposing its rotation.

In this non-limiting example, the method comprises a first step of carrying out a drilling using the tube 10. As illustrated in figure 1 , the displacement device 18 is translated along the mast 16, downwards, so as to move the tube 10 substantially vertically downwards. In parallel, the movement device 18 drives the tube 10 in rotation, in order to cut the ground using the cutting teeth 12, so as to carry out said drilling F. Alternatively, it could be envisaged to vibrate the tube 10 in order to cut the ground S. The tube therefore constitutes a drilling tube.

Without departing from the scope of the invention, drilling F could be carried out using a drilling tool independent of the tube.

The drilling F is carried out so as to at least partially pass through the portions of soil Z1, Z2 to be treated. As we see on the figure 2 , the borehole includes a bottom Fa and a side wall Fb. In addition, said drilling F extends in a drilling direction Y and up to a drilling depth Pf.

In this example, the drilling also passes through the first and second parts of unstable soil S1, S2.

When the tube 10 has reached the desired drilling depth Pf illustrated in figure 1 , a second step is carried out according to which the displacement device 18 is translated along the mast 16, upwards. The tube 10, cooperating with the movement device 18, is therefore also moved upwards and goes up along the borehole F. The tube is then positioned in the borehole at a first predetermined depth P1. More precisely, the tube is positioned so that its distal end 10b extends to said first predetermined depth P1.

Said predetermined depth P1 is less than the drilling depth Pf and less than the depth to which the first portion of soil Z1 to be treated extends. Also, the tube extends above the portion of soil to be treated and opposite the first and second parts of unstable soil S1, S2, likely to collapse. The tube 10 extends in the borehole F, in the drilling direction Y.

The tube then makes it possible to maintain the side wall Fb of the borehole at a height equal to the first predetermined depth P1, and therefore in particular at the level of the first and second parts of unstable ground S1, S2, in order to prevent said side wall Fb from s 'collapse. Furthermore, we note that the diameter of the tube 10 is very slightly less than the diameter of the borehole F so that it substantially matches the side wall Fb of the borehole F. An advantage is to prevent even more effectively the collapse of the side wall of the borehole towards the interior of said borehole F.

The tube 10 is provided at its proximal end 10a with an injection head 20. An example of an injection head 20 is illustrated in figures 12 and 13 . It is preferably mounted removably at the proximal end 10a of the tube.

The injection head 20 comprises a fixed part 22 secured to the displacement device 18, via a rod 23. The injection head 20 further comprises a pivoting part 24 configured to pivot relative to the fixed part 22. Furthermore, the injection head 20 comprises a hole 26 passing through the fixed 22 and pivoting 24 parts and therefore passing through the injection head, from top to bottom along an axis. Said axis coincides with the drilling direction Y when the tube 10 extends in said drilling. The fixed 22 and pivoting 24 parts have a substantially cylindrical shape. The pivoting part 24 cooperates with the proximal end 10a of the tube 10, so that it pivots in the drilling direction Y when the tube is rotated. The injection head further comprises an orifice 25 passing through the fixed 22 and pivoting 24 parts radially. The orifice 25 opens into the through hole 26. Said orifice 25 is configured to be connected to a washing fluid supply source. The injection head also includes pivoting joints 27 arranged between the pivoting part 24 and the fixed part 22.

A first shutter element 30 is then introduced into the borehole, as can be seen in the Figure 3 . In this non-limiting example, the first shutter element 30 is inflatable and has a retracted position in which it is deflated, and an deployed position in which it is inflated. It is further mounted on an injection channel 32, so that said injection channel 32 passes through the first closing element 30. The first closing element 30 is further connected to an inflation member disposed outside the drilling via an inflation pipe. For reasons of readability, said inflation member and said pipe are not shown.

The first closing element 30 is initially placed in the retracted position, around the injection channel 32. Said injection channel and said first closing element in the retracted position are then introduced jointly into the tube 10, via the hole 24 passing through the injection head 20 , and translated towards the bottom Fa of the borehole F. They are moved until the first sealing element 30 exits the tube through its distal end 10b. The first shutter element is brought to a second depth predetermined depth P2, between the first predetermined depth P1 and the drilling depth Pf. The first sealing element 30 then extends between the tube 10 and the bottom of the drilling Fa. The inflation pipe and the injection channel 32 extend in the tube 10 and in the through hole 26 of the injection head 20 and open out of said injection head through its upper end.

Air is then injected into the first closing element 30, via the pipe, using the inflation member. The first obturation element is then inflated and placed in the deployed position, illustrated in Figure 4 . It can therefore be deployed from outside the borehole.

In the deployed position, the first shutter element 30 matches the side wall Fb of the borehole F so that it forms a plug between the drilling parts arranged above and below said first shutter element 30. The first element shutter then defines an injection zone 34 located between said first shutter element 30, the bottom Fa of the borehole F and the side wall Fb of the borehole. The injection zone 34 is arranged opposite the first portion of soil to be treated Z1.

The injection channel 32 is preferably connected to a supply source of injection fluid. As we see on the Figure 4 , the injection channel 32 passes through the injection head 20 and also extends inside the tube 10. It comprises a proximal end 32a projecting from the proximal end 10a of the tube and from the upper end of the injection head 20. The proximal end 32a of the injection channel 32 is connected to the injection fluid supply source. The injection channel 32 also comprises a distal end 32b then extending into the injection zone 34, below the first obturation element 30. The distal end of the injection channel 32 is provided with a nozzle injection 36 configured to project an injection fluid. The injection channel 32 and the injection nozzle 36 form part of an injection device.

We then proceed to inject the injection fluid, illustrated in Figure 5 . The injection fluid may consist of a sealant if it is necessary to seal the ground or a hardening slurry if it is necessary to consolidate the ground. It can also be a grout.

The injection fluid is introduced into the injection channel 32, at the proximal end 32a of said injection channel and propagates in said injection channel from its proximal end to its distal end 32b. It is then injected into the injection zone 34 thanks to the injection nozzle 36 which allows it to be projected substantially radially towards the side wall Fb of the borehole F. The injected injection fluid is represented by the arrows in solid lines. The injection fluid then infiltrates into the soil S and spreads into the first portion of soil Z1 to be treated. This is how the soil is treated.

The first closing element 30 makes it possible to avoid direct projection of the injection fluid towards the tube 10. As can be seen in the Figure 5 , the injection fluid is however likely to bypass the first closing element and to accumulate between said first closing element 30 and the tube 10 or to infiltrate between the tube 10 and the side wall Fb of the drilling. In particular, the injection fluid, possibly mixed with soil particles, forms cuttings which risk infiltrating between the side wall of the borehole and an exterior surface 11 of the tube. This is not desirable to the extent that these cuttings risk disrupting the movement of the tube 10 or even blocking the tube in the drilling.

In accordance with the invention, a step is carried out for evacuating the cuttings located between the tube 10 and the side wall Fb of the drilling, simultaneously with the injection of the injection fluid into the injection zone 34, so as to remove the debris in contact with said tube. More precisely, we carry out a step of cleaning the exterior surface 11 of the tube. Advantageously, only the part of the tube which is in the ground is cleaned.

In this non-limiting example, in parallel with the injection of the injection fluid, the resistant torque applied to the tube is measured using the torque sensor 19. When this resistant torque is greater than a predetermined threshold, it is measured. deduces the presence of cuttings, and in particular injection fluid, in contact with the tube 10 and the cleaning of the tube and the evacuation of the cuttings are then triggered.

Without departing from the scope of the invention, the cuttings evacuation step could be triggered from the start of the injection of the injection fluid into the injection zone 34.

In order to clean the tube 10 and evacuate the debris, the tube 10 is rotated, using the displacement device 18, around an axis of rotation substantially coincident with the longitudinal direction Y of the drilling F. Thanks at this rotation, the injection fluid in contact with the tube does not risk drying out and solidifying. The risk of the tube getting stuck in the ground is therefore greatly reduced. Furthermore, the rotational movement of the tube 10 has the effect of moving the cuttings located between said tube and the side wall Fb of the borehole towards the proximal end 10a of the tube.

Rotating the tube therefore makes it possible to effectively clean its exterior surface 11 and quickly evacuate the debris.

Without departing from the scope of the invention, the exterior surface 11 of the tube could comprise at least one helix making it possible to convey the cuttings towards the proximal end 10a of the tube and therefore towards the exterior of the tube, to facilitate its evacuation. .

At the same time, to clean the exterior surface 11 of the tube and evacuate the debris, a step of injecting a washing fluid is also carried out around the tube 10. The washing fluid may comprise an aqueous solution and cleaning agents. To do this, the washing fluid is introduced into the tube, at its proximal end 10a, via the orifice provided in the fixed 22 and pivoting 24 parts of the injection head 20. The injection head 20 therefore allows inject the washing fluid into the tube 10. The tube is then used as a conduit, so that the washing fluid flows between the injection channel 32 and the tube 10. The washing fluid is brought up to at the distal end 10b of the tube where it is injected into the borehole F. To the extent that the tube 10 pivots, the pivoting part 24 of the injection head 20 is also rotated.

The washing fluid then gradually fills the upper part of the borehole located above the first sealing element and infiltrates between the exterior surface 11 of the tube 10 and the side wall Fb of the borehole. The cuttings, including the injection fluid, present in this upper part of the drilling then mix with the washing fluid, so that the washing fluid carries the cuttings towards the upper end of the drilling and flushes them out of the drilling. This step makes it possible to evacuate the debris and clean the exterior surface 11 of the tube 10 more effectively.

On the Figure 5 , the path of the washing fluid during its injection is represented by dotted arrows.

The coupled action of the washing fluid and the rotation of the tube makes it possible to detach the debris even more effectively in contact with the tube. Rotating the tube together with the injection of the washing fluid therefore allows very effective cleaning of the exterior surface 11 of the tube 10, significantly reducing the risk of blockage of the tube 10 in the borehole F. The injection head 20 and the movement device 18 form a device for cleaning the tube 10 and therefore a device for evacuating the debris located between the tube 10 and the side wall Fb of the borehole F.

On the Figure 6 , we see that the injection fluid has propagated into the first portion of soil Z1, from the injection zone, so that this first portion of Z1 soil has been treated. The dimensions of the first portion of soil Z1 treated depend in particular on the injection time and the quantity of injection fluid injected.

THE figures 7 to 10 illustrate the treatment of the second portion of soil Z2 distinct from the first portion of treated soil Z1 . The second portion of soil Z2 to be treated extends between the first portion of unstable soil S1 and the second portion of unstable soil S2.

Firstly, the tube 10 is moved towards the top of the borehole F and positioned at a first predetermined secondary depth P1' less than the first predetermined depth P1. The tube 10 is then located opposite the second part of unstable ground S2 and makes it possible to maintain the side wall Fb of the borehole F at the level of this second part of unstable ground S2.

As illustrated by the passage from Figure 7 to the figure 8 , the first shutter element 30 is deflated and placed in the retracted position. It is then moved up the borehole F to a second secondary predetermined depth P2' less than the second predetermined depth P2.

As before, the first shutter element 30 is inflated so as to be placed in the deployed position in which it matches the side wall Fb of the borehole. The first shutter element then defines a secondary injection zone 34' located between the first shutter element 30, the bottom Fa of the borehole F and the side wall Fb of the borehole. The secondary injection zone 34' is arranged in particular facing the second portion of soil Z2 to be treated, as can be seen in Figure 9 .

The injection channel 32 and the injection nozzle 36 are also raised in the borehole, facing the second portion of soil Z2 to be treated. As before, the injection fluid is injected into the secondary injection zone 34' so as to treat the second portion of soil Z2. In parallel, the tube is cleaned and the cuttings located between the tube 10 and the side wall Fb of the borehole F are removed. To do this, the tube 10 is rotated using the displacement device 18 and a washing fluid is injected into the borehole F and around the tube 10 using the injection head 20. There- again, the circulation of the washing fluid prevents the cuttings, including the injection fluid, from blocking the tube in the drilling.

As we see on the Figure 9 , the injection fluid has infiltrated into the soil S so that the first portion of soil Z1 and the second portion of soil Z2 are treated.

According to a non-limiting variant, and as illustrated in Figure 10 , we could also have introduced a second shutter element 31 into the drilling at a third predetermined depth P3 between the second secondary predetermined depth P2' and the drilling depth Pf. The second shutter element 31 is then located between the first sealing element 30 and the bottom of the borehole Fa.

The second shutter element 31 is similar to the first shutter element 30 and can also be placed in an deployed position. It therefore makes it possible to reduce the secondary injection zone 34', so that said secondary injection zone 34' therefore extends between the first closing element 30, the second closing element 31 and the wall. lateral Fb of the drilling. An advantage is not to project the injection fluid towards the bottom Fa of the drilling and therefore to locate the injection more precisely.

Without departing from the scope of the invention, the second shutter element 31 may have been introduced at the same time as the first shutter element 30 or after.

As illustrated in Figure 11 , we can then extract the tube 10 out of the drilling, still by moving the guide member 18 along the mast. The first shutter element 30 is also extracted after having placed it in the retracted position and the injection channel 32.

The treatment of the first and second portions of soil Z1, Z2 was therefore carried out by going back, in two successive injection stages, towards the top of drilling F.

Claims (17)

1. A method for treating soil (S) comprising the following steps:

   a tube (10) is supplied having a distal end (10b);

   a borehole (F) is made in the soil, the borehole having a bottom (Fa), a lateral wall (Fb), a borehole depth (Pf) and extending in a boring direction (Y);

   the tube is positioned in the borehole at a first predetermined depth (P1) less than the borehole depth;

   at least one first blocking element (30) is introduced into the borehole at a second predetermined depth (P2) comprised between the first predetermined depth and the borehole depth, so that it extends between the distal end of the tube and the bottom of the borehole, said at least one first blocking element being configured to block the borehole in order to define an injection zone (34) located between said at least one first blocking element, the bottom of the borehole and the lateral wall of the borehole; said method for treating a soil being characterized in that an injection fluid is injected into the injection zone while carrying out a step of removing the cuttings located between the tube and the lateral wall of the borehole, the step of removing the cuttings comprising the cleaning of the outer surface (11) of the tube (10), the step of cleaning the outer surface (11) of the tube (10) comprising the injection of a washing fluid around the tube.
2. The treatment method according to claim 1, characterized in that the step of cleaning the outer surface (11) of the tube (10) comprises the rotation of said tube around the boring direction (Y).
3. The treatment method according to claim 1 or 2, characterized in that the distal end of the tube (10) bears a cutting member (22), and in that the step of boring in the soil (S) is carried out by means of the tube moving in the soil in the boring direction (Y) until the borehole depth (Pf).
4. The treatment method according to any one of claims 1 to 3, characterized in that the diameter of the tube (10) is substantially equal to the diameter of the borehole.
5. The treatment method according to any one of claims 1 to 4, characterized in that a torque sensor (19) is supplied, in that a resisting torque applied to the tube (10) is measured by means of the torque sensor, and in that a possible presence of cuttings in contact with the tube is detected due to the measured resisting torque.
6. The treatment method according to any one of claims 1 to 5, characterized in that said at least one first blocking element (30) has a retracted position in which it can be moved in the borehole (F) and a deployed position in which it cooperates with the lateral wall (Fb) of the borehole to block the borehole in order to define said injection zone (34).
7. The treatment method according to claim 6, characterized in that the introduction of said at least one first blocking element (30) into the borehole (F) comprises the introduction of said first blocking element, in the retracted position, into the tube (10) and the movement of said first blocking element along the tube until the second predetermined depth (P2).
8. The treatment method according to any one of claims 1 to 7, characterized in that the injection of the fluid is accomplished by means of an injection device comprising an injection channel extending inside the tube (10) and leading into the injection zone.
9. The treatment method according to claim 8, characterized in that the injection channel passes through said at least one first blocking element (30).
10. The treatment method according to any one of claims 1 to 9, wherein
    a second blocking element (31) is introduced into the borehole at a third predetermined depth (P3) comprised between the second predetermined depth (P2) and the borehole depth (Pf), so that it is located between said at least one first blocking element (30) and the bottom (Fa) of the borehole (F), said second blocking element being configured to block the borehole so that the injection zone (34') extends between the first blocking element (30), the second blocking element and the lateral wall (Fb) of the borehole.
11. The treatment method according to any one of claims 1 to 10, characterized in that the injection fluid is selected among a waterproofing product and a hardenable mud configured to consolidate the soil (S).
12. The treatment method according to claim 5, characterized in that the washing fluid is injected if a presence of cuttings in contact with the tube (10) is detected by means of the torque sensor (19).
13. The treatment method according any one of claims 1 to 12, characterized in that the washing fluid is injected by the distal end (10b) of the tube (10).
14. The treatment method according to claim 13, characterized in that the step of injecting a washing fluid is carried out by means of an injection head (20) configured to inject the washing fluid into the tube (10), the injection head comprising a fixed part (22) and a pivoting part (24), the pivoting portion being configured to cooperate with the tube (10).
15. A device for treating soil (S) in which a borehole (F) is made having a bottom (Fa), a lateral wall (Fb), a borehole depth (Pf) and extending in a boring direction (Y), said treatment device comprising:

    a tube (10) having a distal end (10b), said tube being configured to be positioned in the borehole at a first predetermined depth (P1) less than the borehole depth;

    at least one first blocking element (30) configured to be introduced into the borehole at a second predetermined depth (P2) comprised between the first predetermined depth and the borehole depth, said at least one first blocking element being configured to block the borehole in order to define an injection zone (34) located between said at least one first blocking element, the bottom of the borehole and the lateral wall of the borehole;

    an injection device (32, 36) configured to inject an injection fluid into the borehole;

    said device for treating soil being characterized in that it comprises a device for removing the cuttings (18, 20) configured to remove the cuttings located between the tube and the lateral wall of the borehole during the injection of the injection fluid into the borehole, by cleaning the outer surface (11) of the tube (10) by injecting a washing fluid around the tube.
16. The treatment device according to claim 15, characterized in that the device for removing the cuttings comprises a movement device (18) configured to set the tube (10) in rotation around the boring direction (Y).
17. The treatment device according to claim 15 or 16, characterized in that the device for removing the cuttings comprises an injection head (20) for injecting a washing fluid around the tube (10).

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