EP3388620B1 - Drilling device and method for creating a hole in the soil - Google Patents

Description

The invention relates to a drilling device for creating a hole, in particular a blind hole, in the ground starting from a starting point to a target point along a drilling line with at least one first arranged on the front of the drilling device Bodenlösemittel for releasing the soil from a working face of the bore in the forward drive direction with at least one first receiving means for the dissolved soil (hereinafter cuttings), with at least one conveying means for removing the cuttings from the first receptacle out of the borehole. Also relevant to the invention is a propelling member for advancing and retracting a drilling apparatus, and a method for creating a bore, in particular a blind hole, in the ground from a starting point to a target point along a drilling line, where the ground is released along the drilling line by means of a boring device with the drilling apparatus being moved via propulsion elements, with a feed device at the starting point, in particular a press frame, along the drilling line to the destination point, and a drilling system for creating a hole, in particular a blind hole, in the ground starting from a starting point to a destination point along a drilling line ,

When drilling boreholes from a start point to a destination point along a given drilling line, various types of tunnel boring machines are used as drilling devices depending on the soil or rock to be used. Such drills come then for use when the drill in the feed without Pilot bore or the like is moved along the drilling line. The movement can take place, inter alia, by advancing or pushing the pipe segments themselves outside the created tunnel. Such a feed then takes place via a feed device, for example a so-called pipe thruster or a press frame, when individual pipe segments are pressed into the ground. The release of the soil takes place with a drilling tool, such as a cutting wheel. The loosened cuttings are brought through the drilling tool into an area behind the cutting wheel and from there carried away (for example, known from DE3514563A ). The choice of the type of drill is made depending on the geology.

If, for example, geologies occur in which boreholes are subject to strong convergence and / or brittle rock conditions, this has an effect on the drilling method to be chosen. These conditions usually occur in hard rock with moderate compressive strengths and greater depths. Experience has shown that the borehole is traced parallel to the drilling progress. Time-dependent convergence can occur during the entire drilling period. This can lead to a jamming of the drilling process by convergence and / or Nachbruch.

Furthermore, the drilling process is affected by the presence of geologies that tend to swell or even dissolve when using water or the like, as is the case with clay, mudstone, salt or shale, for example. Here usually only dry boring methods are used. Wet drilling methods like HDD are ruled out here. In dry drilling methods, for example, no bentonite suspension can be used to reduce skin friction during the advance of drill pipes as a well construction, for example in microtunneling. This significantly reduces the potential drill length and increases the risk of drilling down the wellbore due to trailing or convergence.

Under certain circumstances, it is necessary to drill holes that are not continuous. Such wells also called blind holes are used in particular in repositories to create from a distance below ground holes in which then hazardous materials such as radioactive materials may be stored in protective containers. Here, the hole is created and then the drilling device must be removed from the hole again.

When creating holes that are not continuous and may not be walkable because of the diameter, it is problematic to remove the drilling device out of the hole again. It is known to create such holes in which the drill is advanced by means of drill pipes analogous to the microtunnelling method of a route by means of press frame. The drilling device has a cutting wheel with overcut. Furthermore, the cutting wheel is divided into two parts. The drilling device optionally has an additional outer shell as a lost coat. When the target point is reached, the outer part is released from the cutting wheel and can remain in the ground. The machine itself is separated from the outer shell and is pulled out of the borehole together with the inner cutter wheel through the drill pipes acting as a lost extension. This is complicated, expensive and associated with high costs. Convergences and debris can cause sticking during drilling.

Especially with disposal bores, it may be necessary to bring special expansion in the hole. This may not be applicable as a drill pipe. It must then be created an undeveloped hole. For this, if necessary, the HDD method would own, but which is not applicable in the aforementioned geologies. That's why microtunneling is used. But pulling the drill backwards becomes a risk. Furthermore, due to the convergences and the possible Nachfall the problem is to provide a hole with straight straight diameter undeveloped, then then bring the final expansion in the hole. Even if the machine has been successfully withdrawn, the hole may not be usable for the final removal or storage of the containers due to the demolition and the convergences.

The object of the invention is to overcome the aforementioned difficulties.

The object is achieved by a drilling apparatus having at least one second soil dissolving means disposed at the rear of the drilling apparatus for releasing soil from the wall of the already established borehole in the retreating direction upon withdrawal from the borehole, with at least one second receptacle for receiving cuttings during the retreat of the boring cuttings Drilling device, and with at least one transport means for removing the cuttings from the at least one second receptacle to the conveyor or from the borehole out.

By re-cutting the necessary hole diameter for the successful withdrawal of the drilling device is ensured. On the other hand, the broadening and the same diameter completion of the hole / blind hole is achieved by clearing of Nachbruch in the tunnel sole and the cutting of converged rock parts in the planned cavity. Thus, the final expansion can be safely introduced, even under the above-described mountain conditions / geologies.

The second soil release agent may be a passive cutting edge or an active cutting ring.

A further teaching of the invention provides that the soil release agent in the advancing direction is a separating wheel in full section or partial section with a drive. For the drill head, funding and rear transport each advantageously has its own drive. The separation of drill head drive and conveyor drive is important in order to ensure the necessary torque at the drill head over long distances without the losses on the conveyor. It is also advantageous if the drilling head and means of transport can be operated independently of the conveying means by e.g. to loosen jammed boulders or break.

Another teaching of the invention provides that it is the conveyor to a screw conveyor, a liquid circuit with a pump, such as a centrifugal or jet pump, or a belt conveyor and / or that it is the transport means to a screw conveyor, a fluid circuit with Pump, a circulating medium in which by means of rotating vessels or paddles the cuttings is promoted, or is a belt conveyor.

A further teaching of the invention provides that the drilling device is made up of several sections, that the soil release agent is arranged at the front section and that at least one control means, preferably in the form of at least one hydraulic cylinder, is provided between the front section and at least one further section of the drilling device ,

A further teaching of the invention provides that the drilling device is made up of several sections, that at a portion of the second soil solvent is disposed, and that between this and at least one further portion of the drilling device, of the is arranged behind the second bottom solvent, as seen from the first bottom solvent, at least one control means, preferably in the form of at least one hydraulic cylinder, is provided. This makes it possible to keep the drilling device or the rear-facing cutting device controlled on the desired axis.

A further teaching of the invention provides that a measuring device is provided at least at this further section for determining bottom projections of the borehole wall into the borehole or from loosened soil on the bottom of the borehole. By using such measuring technique it becomes possible to record the contour of the borehole. Furthermore, it is advantageous if the position of the machine can be determined by the measuring device to the desired axis of the borehole. Furthermore, monitoring of the nominal diameter in comparison to the actual diameter of the borehole is advantageous. That measurement can be done for example by laser measurement or acoustically.

Relevant to the invention is a propulsion element for advancing and retracting a drilling device, in particular a drilling device as described above, having a drilling direction extending force transmission element having at its end portions a connecting element for producing a detachable connection with the drilling device or further propulsion elements, with at least one conveying element, is provided in or on the power transmission element, with at least one receptacle of supply lines, which is provided in or on the force transmission element, and with at least one movement element, via which the propulsion element is movable relative to the borehole wall in contact therewith, wherein the movement element via a Distance element is arranged on the power transmission element.

The propulsion elements are designed so that they transmit the forces for propulsion and retreat, record the funding and the necessary lines for the operation of the drilling device. At the same time, the shape of the propulsion elements is designed so that the propulsion and retraction are also possible at Nachbruch and convergences in a certain extent. This is achieved in that the propulsion elements are not tubular and thus have no narrow annular gap to the mountains, but provide enough space to accommodate Nachbruch / pass or allow convergences. The reduced contact surface by the movement elements, for example in the form of sliding elements such as runners or tubes in the lower region ensures a well calculable low skin friction between propulsion element and mountains.

A further teaching of the invention provides that the conveying element is a screw conveyor or a pipeline.

A further teaching of the invention provides that at least three spacer elements are radially arranged radially on the force transmission element.

A further teaching of the invention provides that at least one spacer element is designed to be adjustable in length during use in the borehole, in particular via a hydraulic cylinder. This makes it possible to control the drilling device or the rearward cutting device and to keep controlled on the target axis.

A further teaching of the invention provides that the propelling element has at least one measuring device for determining bottom projections of the borehole wall into the borehole or of dissolved soil on the bottom of the borehole. By using such measuring technique it becomes possible to record the contour of the borehole. Furthermore, it is advantageous if the position of the machine can be determined by the measuring device to the desired axis of the borehole. Furthermore, monitoring of the nominal diameter in comparison to the actual diameter of the borehole is advantageous.

Another teaching of the invention provides that the propulsion element is designed so that the movement elements only selectively support the borehole wall with respect to the propulsion element.

Furthermore, the object is achieved by a method for creating a hole, in particular a blind hole, in the ground starting from a starting point to a target point along a drilling line, in which the soil along the drilling line by means of a drilling device, in particular a drilling device as described above, is achieved wherein the drilling device is moved via at least one propulsion element, in particular a propulsion element as described above, with a feed device at the starting point, in particular a press frame, along the drilling line to the target point, and in reaching the target point, the drilling device along the drilling line by removing the propulsion elements is moved back by means of the feed device, wherein upon retraction projecting into the wellbore bottom projections of the borehole wall are released from a arranged at the back of the drilling device second soil solvent and thereby dissolved Soil and other located on the bottom of the well dissolved soil is taken up by the drilling device and transported away from the well.

A further teaching of the invention provides that with a measuring device bottom projections of the borehole wall, which project into the borehole, or dissolved soil on the bottom of the borehole is determined, and / or that the position of the arranged at the back of the boring device second soil release means in relation is controlled to the drilling line and / or the optimal position of the borehole wall in the ground, wherein preferably the control is carried out depending on the measurement result of the measuring device. By using such measuring technique it becomes possible to record the contour of the borehole. Furthermore, it is advantageous if the position of the machine can be determined by the measuring device to the desired axis of the borehole. Furthermore, monitoring of the nominal diameter in comparison to the actual diameter of the borehole is advantageous. This makes it possible to control the drilling device during retraction and so to keep the backward cutting device controlled on the desired axis.

Furthermore, the object is achieved by a drilling system for creating a bore, in particular a blind hole, in the ground starting from a starting point to a target point along a drilling line, in particular according to a previously described method, with a previously described drilling device and at least one driving element described above.

Fig. 1

eine schematische Schnittdarstellung einer erfindungsgemäßen Bohrvorrichtung,

Fig. 2

eine schematische Schnittdarstellung eines erfindungsgemäßen Vortriebselements,

Fig. 3

eine Frontansicht zu Fig. 2,

Fig. 4

eine schematische Schnittdarstellung einer erfindungsgemäßen Bohrvorrichtung und eines erfindungsgemäßen Vortriebselements mit erfindungsgemäßer Steuerung und Messvorrichtung,

Fig. 5

eine Frontansicht zu Fig. 2 mit Messvorrichtung,

Fig. 6 bis Fig. 10 und Fig. 13

eine schematische Darstellung der Schritte des erfindungsgemäßen Verfahrens,

Fig. 11

eine schematische Darstellung eines Bohrlochs mit Nachfall und Konvergenz, und

Fig. 12

eine schematische Darstellung eines Bohrlochs nach Durchführung des erfindungsgemäßen Verfahrens.

The invention will be explained in more detail with reference to an embodiment in conjunction with a drawing. Showing:

Fig. 1

a schematic sectional view of a drilling device according to the invention,

Fig. 2

a schematic sectional view of a driving element according to the invention,

Fig. 3

a front view too Fig. 2 .

Fig. 4

a schematic sectional view of a drilling device according to the invention and a driving element according to the invention with inventive control and measuring device,

Fig. 5

a front view too Fig. 2 with measuring device,

FIGS. 6 to 10 and FIG. 13

a schematic representation of the steps of the method according to the invention,

Fig. 11

a schematic representation of a well with Nachfall and convergence, and

Fig. 12

a schematic representation of a borehole after performing the method according to the invention.

Fig. 1 shows a schematic sectional side view of a drilling device according to the invention 10. This has a first soil release agent 11 in the form of a front cutting wheel. The cutting wheel 11 is driven by a drive 12. Behind the cutting wheel 11, a first receptacle 13 is provided for receiving the soil dissolved by the cutting wheel 11, which is described below as cuttings. Into the receptacle 13 protrudes the conveyor 15 for the removal of the cuttings from the first receptacle 13 from the borehole 100 out. Arranged on the rear side 14 of the drilling apparatus 10 is a second soil dissolving means 16 for releasing soil from the wall 101 of the already created borehole 100 in the withdrawal direction during the withdrawal from the borehole 100. The second soil release agent 16 is designed here as a circumferential annular cutting edge which is arranged diagonally. The second soil release agent / the annular cutting edge 16 can also serve to receive replacements 103 or cuttings located on the sole 102. This passes into a second receptacle 17. In this engages a possibly separate driven transport 26 here in the form of rotating paddles to receive the cuttings received there and convey off, preferably in the conveyor 15 through the opening 18th

The cutting wheel 11 is arranged on a first portion 19. This is movably provided with respect to the second section 20 via control cylinders 21. The conveyor 15 is driven by a drive 22. The transport means 26 has its own drive 24.

The conveying means 15 has on the rear side 14 a connection 23 in the form of a flange for a driving element 30 according to the invention. In the area of the annular cutting edge 16, a laser target 25 for direction monitoring of the pipe jacking is arranged.

Fig. 2 shows an inventive driving element 30. This has a extending in mining device central power transmission element 31. In this one is Section of the conveyor 15, here a screw conveyor, provided. At its outer ends, the power transmission element 31 in each case has a connection 32 in the form of a flange. Via screw connections, the propulsion element 30 can be connected with its connections 32 to the drilling device 10 according to the invention or to other propulsion elements 30. This provides a connection with which both tensile and compressive forces can be transmitted. On the power transmission element 31, a receptacle 33 is provided, in the example, supply lines 34 (see FIG. 3 ) are arranged. The receptacle 33 is preferably designed so that the supply lines 34 can be inserted into the receptacle 33. For the Aufnahme33 is executed u-shaped and can be closed with a lid 35. At the force transmission element 31 here preferably star-shaped spacer elements 36 are arranged, at the end of which movement elements 37 are preferably designed here as a tube. The movement elements 37 are here sliding elements over which the drive element 30 along the borehole 100 can be moved. Holes are provided in the connection 32, into which bolts 38 for producing the connection of the individual connection elements 32 with one another can be introduced.

Fig. 4 shows a drilling device 10 according to the invention with it and behind it arranged connecting elements 30. The drilling device 10 and the connecting elements 30 are arranged in the wellbore 100. The first propulsion element 30 thereby represents a control and measuring element. The spacer elements 36 are provided with hydraulic cylinders 39, so that they can be changed in their length in the direction of arrow A. The first propulsion element 30 acts as a kind of third section 27 of the drilling device 10th If the boring device 10 is retracted in the direction of the arrow B via the driving elements 30, the cuttings 103 located on the sole 102 can be conveyed into the second receptacle 17 in the direction of the arrow via the annular cutting edge 16.

About the change in length of the spacers 36 by extending and retracting the hydraulic cylinder 39, the moving elements 37 are moved in the direction of arrow A. As a result, the moving elements 37 are either moved away from the conversion 101 of the borehole or pressed into this. As a result, the position of the force transmission element 31 changes, whereby the position of the annular cutting edge 16 with respect to the wall 101 is also moved directly in the direction of the arrow A.

Continue to show Fig. 4 and Fig. 5 a measuring device 40, which is arranged circumferentially on the force transmission element 31. With the measuring device 40, the contour of the borehole 100 can be measured. It can thus breakouts 104 and, for example, caused by convergence projections 105 are detected. Based on the measurement data of the measuring device 40 can then be controlled via the hydraulic cylinder, the position of the annular cutting edge 16 so that when retracting an optimal borehole shape with respect to the intended hole line can be created.

The difference of a borehole contour with inventive method and without is in the Figures 11 and 12 shown. FIG. 11 shows a wellbore 100 with outbreaks 104 and protrusions 105 with respect to the wellbore conversion 101. In the area of the outbreaks 104, cuttings 103 are located on the bottom 102 of the wellbore 100. In FIG. 12 the borehole 100 is shown with sole 102 cleared by cuttings 103. Furthermore, the projections 105, which were caused by convergence or sources, peeled off by the annular cutting edge 16 on the drilling apparatus 10 and the cuttings 103 incurred thereby also carried away.

In such an adjusted hole 100 then required for example for the final storage expansion elements 110 can be introduced into the wellbore 100 by means of a press frame 50 as a feed and retraction element, as this in FIG. 13 is shown. The press frame 50 is arranged in an underground section 120 of a repository mine from which the bore 100 is generated. The arrangement of the press frame 50 in the track 120 is also in FIG. 6 shown. The press frame 50 is aligned in the direction of a Bohrlochansatzpunktes 106.

The drilling device 10 according to the invention is arranged in the press frame 50 in the direction of the Bohrlochansatzpunktes 106 (see FIG. 7 ). When the cutting wheel 11 of the drilling apparatus 10 is put into operation, the press frame 50 pushes the drilling apparatus 10 in the direction of the drilling line D (see FIG FIG. 8 ) until there is sufficient space in the area of the press frame 50 in order to arrange the first drive element 30 (see FIG FIG. 9 ). The first drive element 30 is then pushed by the press frame 50 with its front terminal 32 against the terminal 23 and the two elements are connected with bolts 38. At the same time the supply lines 34 are inserted into the receptacle 33. The receptacle 33 is then closed with the lid 35.

Subsequently, the feed element 30 and the drilling device 10 is advanced through the press frame in the drilling direction D for creating the borehole 100, until in turn there is sufficient space for a further driving element 30 in the region of the press frame 50. This is repeated until the borehole 100 has arrived at the destination point. Subsequently, via the press frame 50, the driving elements 30 and the drilling device 10 as in FIG. 4 shown withdrawn in the direction of arrow B, wherein the borehole 100 is straightened by means of the annular cutting edge 16 with respect to the target line. Furthermore, the cuttings 103 located on the sole 102 are received by the drilling device 10. The feed elements 30 are successively removed and further retracted from the press frame in the direction of arrow B in the route 120 inside.

After removal of the drilling device 10 can then as in FIG. 13 is shown, the final expansion 110 are introduced. By rapidly disassembling and then clearing the wellbore 100 as described, it is possible to insert the final disassembly 110 into the wellbore 100 without further delay, so that further convergence or resulting protrusions 105 and / or outbreaks 104 can be minimized ,

By the method described above and the illustrated system consisting of drilling device 10 and before operating elements 30, it is possible to drill boreholes or blind bores also in geology efficient, which require a dry work. Furthermore, it is possible to achieve larger jacking lengths, since the friction of the drill string is minimized compared to the use of solid tubes. Furthermore, the risk of sticking during the drilling progress is minimized because the mountains are given room for convergence and at the same time no jamming of the jacking pipes can be made against the borehole. Furthermore, it is not necessary to use lost expansion. It is also possible to create and re-drill holes between two achievable points in the previously described manner or using the method according to the invention, the drilling system according to the invention and its components according to the invention. It is also possible to drive on multiple holes in order to recut.

The invention can be used in particular in non-accessible diameter ranges up to diameters, from which, for example, segment lining can be used. However, this is not restrictive. As an alternative to a route underground, the invention can also be applied from a launch pit or the like above ground. <B> LIST OF REFERENCES: </ b> 10 drilling 50 press frame 11 first soil solvent / front cutting wheel 100 well 12 drive 101 wall 13 first recording 102 sole 14 back 103 Subsequent breaking / cuttings 15 funding 104 outbreak 16 second soil solvent / cutting ring 105 head Start 17 second shot 106 Borehole starting point eighteen opening 110 expansion element 19 first section 120 route 20 second part 21 control cylinder A arrow 22 drive B arrow 23 Connection / flange C arrow 24 drive D drilling direction 25 laser target 26 Mode of Transport 27 third section 30 propulsion element 31 Power transmission element 32 connection 33 admission 34 supply line 35 cover 36 spacer 37 mover 38 bolt 39 hydraulic cylinders 40 measuring device

Claims (17)

1. Drilling device for creating a hole (100) in the soil, starting from a starting point (120) to a target point along a drilling line,
   having at least one first soil loosening means (11) arranged on the front side of the drilling device (10) for loosening the soil from a working face of the hole in the propulsion direction during propulsion,
   having at least one first receptacle (13) for the loosened soil (cuttings hereinafter),
   having at least one conveying means (15) for transporting the cuttings from the first receptacle (13) away out of the borehole, characterized in that the drilling device is provided:

   with at least one second soil loosening means (16) arranged on the rear side (14) of the drilling device (10) for loosening soil from the wall (101) of the borehole already created in the withdrawal direction during withdrawal out of the borehole,

   with at least one second receptacle (17) for receiving cuttings as the drilling device is withdrawn, and

   with at least one transport means (26) for transporting the cuttings from the at least one second receptacle (17) away to the conveying means (15) or out of the borehole.
2. Drilling device according to Claim 1, characterized in that the soil loosening means (11) in the propulsion direction is a full-cut or partial-cut separating wheel with a drive.
3. Drilling device according to Claim 1 or 2, characterized in that the conveying means (15) is a screw conveyor, a liquid circuit with pump or a belt conveyor.
4. Drilling device according to one of Claims 1 to 3, characterized in that the transport means (26) is a screw conveyor, a liquid circuit with pump, a circulating conveying medium or a belt conveyor.
5. Drilling device according to one of Claims 1 to 4, characterized in that the drilling device is built up from multiple sections (19, 20), in that the first soil loosening means (11) is arranged on the front section (19), and in that at least one control means (21) is provided between the front section (19) and at least one further section (20) of the drilling device.
6. Drilling device according to one of Claims 1 to 5, characterized in that the drilling device (10) is built up from multiple sections (19, 20), in that the second soil loosening means (16) is arranged on a section (20), and in that at least one control means is provided between this section and at least one further section of the drilling device (10) which, seen from the first soil loosening means, is arranged behind the second soil loosening means.
7. Drilling device according to one of Claims 1 to 6, characterized in that a measuring device (40) for determining soil protrusions (105) of the borehole wall into the borehole (100) or loosened soil (103) on the base (102) of the borehole (100) is provided, at least on this further section.
8. Method for creating a hole (100) in the soil, starting from a starting point (120) to a target point along a drilling line, in which the soil along the drilling line is loosened by means of a drilling device (10) according to one of Claims 1 to 6, the drilling device (10) being moved along the drilling line to the target point via at least one propulsion element (30) having a feed device (50) at the starting point (120), characterized in that after the target point has been reached, the drilling device (10) is moved back along the drilling line by removing the propulsion elements (30) by means of the feed device (50), wherein, during the withdrawal, soil protrusions (105) of the borehole wall (101) that project into the borehole (100) are loosened by a second soil loosening means (16) arranged on the rear side (14) of the drilling device (10), and the soil (103) loosened in the process and further loosened soil (103) found on the base of the borehole is picked up by the drilling device (10) and transported away out of the borehole.
9. Method according to Claim 8, characterized in that soil protrusions (105) of the borehole wall (101) that project into the borehole (100), or loosened soil (103) on the base (102) of the borehole (100) is/are determined with a measuring device (40).
10. Method according to Claim 9, characterized in that the control is carried out on the basis of the measured result from the measuring device (40).
11. Method according to one of Claims 8 to 10, characterized in that the position of the second soil loosening means (16) arranged on the rear side (14) of the drilling device (10) in relation to the drilling line and/or the optimal position of the borehole wall (101) in the soil is controlled.
12. Drilling system for creating a hole (100) in the soil, starting from a starting point (120) to a target point along a drilling line, with a drilling device (10) according to one of Claims 1 to 6 and at least one propulsion element (30) for pushing forward and withdrawing the drilling device (10), having a force transmitting element (31) which extends in the drilling direction, which on its end sections has a connecting element (32) for producing a detachable connection with the drilling device (10) or further propulsion elements (30), having at least one conveying element (15), which is provided in or on the force transmitting element (31), and having at least one receptacle (33) for supply lines (34) for the drilling device (10), which is provided in or on the force transmitting element (31), and having at least one movement element (37), by which the propulsion element (30) can be moved relative to the borehole wall (101), in contact with the latter, wherein the movement element (37) is arranged on the force transmitting element (31) via a spacer element (36).
13. Drilling system according to Claim 12, characterized in that the conveying element (15) of the propulsion element (30) is a screw conveyor or a pipeline.
14. Drilling system according to Claim 12 or 13, characterized in that at least three spacer elements (36) are arranged radially in the form of a star on the force transmitting element (31) of the propulsion element (30).
15. Drilling system according to one of Claims 12 to 14, characterized in that at least one spacer element (36) of the propulsion element (30) is designed to be longitudinally adjustable during the use in the borehole (100).
16. Drilling system according to one of Claims 12 to 15, characterized in that the propulsion element (30) has at least one measuring device (40) for determining soil protrusions (105) of the borehole wall into the borehole (100) or loosened soil (103) on the base (102) of the borehole (100).
17. Drilling system according to one of Claims 12 to 16, characterized in that the propulsion element (30) is designed such that the movement elements (37) support the borehole wall (101) with respect to the propulsion element (30) only at points.

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