DE102020119032A1 - Method of preparing or making a bore in a ground - Google Patents

Abstract

A method for preparing or producing a bore in a ground for laying a line in the bore comprises the steps of arranging a drill pipe arranged on a pilot drill head at a starting point in the ground, driving and guiding the pilot drill head in the ground on a predefined path from the Starting point to an ending point for making a pilot hole, and retracting the drill string with the pilot bit to the starting point. According to the invention, the step of guiding an injection tool through the pilot bore, coupled with a movement of the pilot drill head, is provided, which at least in certain areas applies a consolidation agent into the adjoining soil to solidify the soil.

Description

The invention relates to a method for preparing or producing a bore in a ground according to the preamble of claim 1. In particular, the method can be used as a preparation for laying a line in the bore.

Horizontal drilling methods are known for laying lines, for example pipelines, empty pipes or electrical lines in the ground, which, instead of a ditch, produce a substantially horizontal borehole for the passage of the lines in the ground. The horizontal directional drilling method, also known as "Horizontal Directional Drilling" (HDD), is used particularly frequently.

As for example in EP 2 863 003 A2 shown, in order to insert the new pipeline in the ground, a first pilot bore is first made in the ground between a starting point and a target point. For this purpose, a starting pit is made at a starting point and a pilot drilling head is inserted into the ground within this starting pit. A target pit is provided at the intended target point, in which the pilot drilling head emerges again.

The pilot drill head is preferably arranged on a drill rod which is lengthened in sections and is continuously fed into the borehole during drilling. The course and direction of the pilot hole can be controlled by influencing the pilot drill head. After the pilot hole has been drilled, the pilot drill and drill rods are pulled out of the hole and back to the starting point.

The pilot bore can then be widened to a diameter that corresponds to the outside diameter of the line to be laid by clearing it out using a clearing drill. Before the reamer is pulled back, the line to be laid is attached to the drill head and the line is pulled into the widened borehole as the reamer is pulled out.

Due to the different geological properties of the ground, it can happen when the pilot drill head and/or the reaming drill is retracted that the borehole partially collapses or collapses, for example in the area of sandy or gravel-filled soil sections. However, if the pilot bore is no longer passable due to collapsed borehole sections, the subsequent clearing bore cannot be carried out and the line to be laid cannot be pulled in.

DE 198 08 478 C2 also uses the horizontal drilling technique to first create a pilot hole. Once this is completed, a special drilling machine is used, equipped with a scraping disc, cutter wheel or drill head, which can crush larger stones with the help of an integrated crushing tool. The drilling machine is used at the end point of the pilot hole and widens the pilot hole to the required diameter. At the same time, the pipeline to be laid is drawn into the borehole with the drilling machine. Here, too, there is a risk that when the pilot drill is pulled back, the ground will collapse at least in sections due to the geological conditions and the pipeline cannot be pulled in.

Out WO 2015 197 828 A1 discloses a method for creating a borehole in the ground and for laying a pipeline in the borehole, in which a combination of an outer pipe and an inner pipe is used, with the outer pipe and a drill head coupled to the inner pipe being advanced separately in order to achieve longer ranges to achieve better buckling resistance.

The aim of the invention is to overcome the disadvantages of the prior art and to create a method with which a bore can be stably produced through the subsoil, so that in particular a pipeline to be laid can always be laid quickly and reliably in the ground.

Main features of the invention are set out in the characterizing part of claim 1. Configurations are the subject of claims 2 to 13.

The subject matter of the invention is also the use of a solidifying agent discharged into the surrounding soil of a pilot borehole produced by a horizontal drilling method for the purpose of solidifying a pilot borehole according to claim 14. An embodiment is the subject matter of claim 15.

A method for producing a bore in a ground for laying a line in the bore is proposed, which comprises the steps of arranging a drill pipe arranged on a pilot drill head at a starting point in the ground, driving and guiding the pilot drill head in the ground on a predefined path from the start point to an end point for making a pilot hole, and retracting the Includes drill pipe to the starting point. According to the invention, the step of guiding an injection tool through the pilot bore, coupled with a movement of the pilot drill head or the drill rod, is provided, which at least locally applies a consolidation agent to the adjoining soil for consolidation of the soil.

Depending on the pressure of application and the nature of the soil, the solidifying agent can be pressed more or less deeply into the soil surrounding the borehole. Injection materials that harden after injection are used as solidifying agents.

The starting point could be located in a first pit as mentioned above. The pilot drill head can be driven through the ground in particular by a rotary drive. As an alternative or in addition to this, hitting the pilot drilling head is also conceivable. Known sensors can be used to determine the current position of the pilot drill head and influence the corresponding control of the drilling mechanism in order to follow the predefined path. Consequently, the method according to the invention begins with a controllable horizontal drilling method for producing a continuous pilot bore between the starting point and the end point.

According to the invention, the pilot bore is stabilized by an injection tool that is guided through the pilot bore. In this case, the injection tool is guided in conjunction with a movement of the pilot drill head or the drill rods. This means that when the drill rods of the pilot drill head are still in the pilot drill hole, the injection tool is guided in the pilot drill hole. It is initially irrelevant how the injection tool is coupled to the movement of the pilot drill head or the drill rods. In one embodiment, after the pilot hole is complete, the injection tool can be attached to the drill string or pilot drill bit. As an alternative to this, it could also already be arranged on the drill string behind the pilot drill head. Due to the coupled guidance, the solidifying agent can be applied in situ immediately after the progressive production of the well.

In a preferred embodiment, an aqueous bentonite or cement suspension, a reaction resin that hardens by polymerisation (chemically hardening adhesive) or a physically setting adhesive (e.g. solvent-based adhesives) is used as the strengthening agent. Polymerization as a generic term here includes polyaddition, polycondensation and free-radical polymerization, i.e. a reaction resin that cures by polyaddition, polycondensation or free-radical polymerization can be used as the reaction resin. A reaction mass based on acrylate or silicate resin or a reaction mass based on polyurethane is preferably applied as a solidifying agent in the vicinity of the drilled hole.

It is particularly preferred that the injection tool is coupled to the pilot drill head at the end point or, optionally after decoupling the pilot drill head, to the drill pipe and selectively discharges the solidifying agent when the drill pipe is pulled back to the starting point. As a result, the pilot drill head is driven completely through the ground to the intended end point and then projects out of the second pit located there at the end point. The injection tool can then be connected to the pilot drill head or connected directly to the drill string after decoupling the pilot drill head. It might be advisable to make a non-rotatable connection with the pilot drill head so that the injection tool does not twist.

As an alternative to this, the injection tool could be moved with the pilot drilling head when the pilot bore is being made, and the solidifying agent could be selectively discharged in the process. As explained above, the injection tool could also already be arranged behind the pilot drilling head and be guided through the already existing section of the pilot drilling directly when the pilot drilling is being made. It is conceivable that the injection tool will then already carry out a consolidation of the soil where necessary when creating the pilot bore.

In a particularly advantageous embodiment, the solidification agent is injected radially (with respect to the central axis of the bore) from the injection tool onto the surrounding soil. The application can be distributed around the entire circumference so that a closed, tube-like shell of solidification agent is formed. Alternatively, the application can be done selectively only in a desired area of the circumference, so that eg only a half-shell or another segment of a shell of solidification agent is formed if solidification of the soil around the well is only desired there. The injection tool can consequently have nozzles, openings and/or slots which are distributed around the circumference of the injection tool and through which the consolidating agent is applied radially to the surrounding soil. The drill string may provide the necessary tubing for the consolidant and others. In the case of very loose ground In areas where there is a risk of the borehole collapsing again immediately after it has been drilled, it may be necessary to press a large quantity of consolidation agent forwards into the ground in front of the pilot drill head, so that a zone whose diameter is greater than the diameter of the To be created bore extends, thereby solidified. This consolidated zone is then drilled through, leaving consolidated areas around the wellbore. In these cases, the injection tool can have a line running close to or through the pilot drill head, with which consolidating agent can be injected into a zone lying in the drilling direction in front of the pilot drill head.

In principle, a distinction can be made between injections of solidifying agent into the borehole environment, which take place later, in parallel or ahead of the borehole production. The injection is referred to as trailing if the injection tool follows the pilot drill head at some distance or is only pulled through the drilled hole when the drill rod is pulled back; Such a procedure can be used if the soil surrounding the bore has a certain basic strength, so that it can be assumed that the bore is stable for at least a certain time until the injection tool is guided through the bore. Simultaneous or parallel injection is considered to be injection made by an injection tool immediately following or a very short distance behind the tip of the pilot drill bit and injecting consolidating agent into the straight hole area being drilled. In this case, the injection direction is primarily radial, i.e. the solidifying agent is pressed perpendicularly to the drilling direction and 360° around the axis of the drilling direction into the soil surrounding the borehole. In the case of such an injection that is parallel or simultaneous with the drilling process, this is practically already stabilized by hardening solidifying agent when a longitudinal section of the bore is being produced. In the case of anticipatory or anticipatory injection, consolidating agent is pressed into the area in front of the pilot drill head in the drilling direction, thereby stabilizing the soil in the area of the borehole with hardened consolidating agent even before it is drilled. As already mentioned, such a procedure is required in the case of very loose areas where a drilled hole would otherwise be buried again immediately or after a short time. For such an advance injection, the injection tool may have lines or lances which are positioned at least temporarily so that they pass close to or through the pilot drill head and have their injection opening directed towards the area in front of the pilot drill head. It is also possible to combine several of the three injection methods described.

In the case of subsequent or parallel injection, the course of hardening of the consolidating agent over time must be adapted to the movement of the injection tool through the bore through its chemical formulation in such a way that the injection tool has already left an area into which the consolidating agent has been injected before the consolidating agent has completely hardened is. This can prevent hardened hardening material from hardening on the injection tool and being pulled along with it.

Furthermore, the strength of the soil could be analyzed before or during the drilling of the pilot hole. The analysis could be carried out by externally placed probes in the ground. As an alternative to this, a sensor system could be provided which allows the soil to be examined directly inside the pilot borehole when the pilot borehole is being made or immediately thereafter.

When drilling the pilot hole, the condition of the washed out material could be examined to analyze the strength of the soil. Consequently, the condition of the soil in particular is continuously examined to assess its strength.

The injection tool could discharge the consolidant in areas of the pilot hole where the strength is below a desired minimum strength. The areas in which the strength of the soil is not sufficient to ensure the stability of the pilot bore could be stored electronically, for example, in order to subsequently solidify them one after the other, controlled by a control unit.

It is advantageous if, during the discharge of the consolidating agent, at least a partial area, i.e. a longitudinal section, of the pilot borehole is separated from adjacent areas and the consolidating agent is discharged exclusively in the partial area for consolidating the soil. This allows the solidifying agent to be discharged by means of an overpressure in the corresponding sub-area, so that individual sub-areas can be solidified efficiently and the solidifying agent does not flow into adjacent areas of the pilot bore.

It is also conceivable that several partial areas of the pilot bore are solidified. For example, the partial areas could lie next to one another or be spaced apart from one another. It can it is advisable to provide two opposite axial boundaries of a portion always at a constant distance in order to strengthen larger areas, for example by successively treating several small portions of fixed dimensions. This limits the size of the injection tool and constant flow conditions can always be guaranteed in the limited sub-areas.

It is advantageous to expand two sealing elements that are spaced apart from one another along the pilot bore to separate a respective partial region and to contract after the solidifying agent has been discharged. The sealing elements could be, for example, fluid-inflatable annular cushion-like devices that can be selectively expanded and contracted. Using a soft, elastic material allows for a good seal against the ground.

After the contraction, the partial area containing the strengthening agent could be compressed radially by means of the sealing elements. It might be advisable to use these sealing elements to partially compress the soil radially in order to achieve particularly good consolidation.

After fully retracting the pilot drill head and drill string, reaming the pilot hole and pulling in the line can be performed. This equips the well with the line through the well in the ground.

The invention further relates to the use of a solidifying agent discharged into the surrounding soil of a pilot bore hole produced by a horizontal drilling method for solidifying a pilot bore hole.

In this case, the solidifying agent could be discharged in situ when the pilot bore is made or when a pilot drill head is withdrawn.

• 1 einen schematischen Querschnitt des Untergrunds nach Einbringen der Pilotbohrung,
• 2 den schematischen Querschnitt beim Ankoppeln des Injektionswerkzeugs und
• 3 den Querschnitt beim Verfestigen des eines lockeren Bereichs des Erdreichs um das Bohrloch.
• 4 eine blockbasierte, schematische Darstellung des Verfahrens.

Further features, details and advantages of the invention result from the wording of the claims and from the following description of exemplary embodiments with reference to the drawings. Show it:

• 1 a schematic cross-section of the subsoil after drilling the pilot hole,
• 2 the schematic cross section when coupling the injection tool and
• 3 the cross-section when consolidating a loose area of soil around the borehole.
• 4 a block-based, schematic representation of the method.

In 1 shows a schematic cross section through an underground area through which a horizontal drilling machine 6 has created a pilot hole 8 . This extends from a starting point 1 in front of the horizontal boring machine 6 to an end point 5. For this purpose, a pilot boring head 2 on a boring bar 3 can be guided through the ground on a desired path. The pilot bore 8 leads, for example, through a soil area 10 with loosened soil.

After making the pilot hole 8 as in 1 shown, the pilot drill head 2 protrudes at the end point 5 from the ground. The drill string extends through the entire pilot hole 8, thereby preventing the collapse of the adjacent soil. An injection tool 4 is now coupled to the pilot drilling head 2; alternatively, the pilot drill head 2 can be uncoupled from the drill string and as in 2 shown an injection tool 4 are coupled directly to the drill string 3.

The injection tool 4 is in 2 shown schematically as a cylindrical body having an internal cavity communicating with a series of injection ports 9 on the surface of the injection tool 4. The injection openings 9 are preferably distributed around the circumference of the injection tool 4 and are intended to be able to release a solidifying agent. The drill rod 3 is pulled back through the pilot bore 8 with the injection tool 4 arranged thereon, with the solidifying agent being released at least in certain areas during the pulling back where it is needed.

In particular, when the injection tool 4 reaches the loose area 10 when it is pulled back, the solidifying agent is pressed under pressure into the injection tool 4 and is thereby pressed out of its injection openings 9 into the surrounding soil. This will in 3 shown. If the injection openings 9 are correspondingly distributed around the circumference of the injection tool 4, a closed, tubular shell is thereby produced from the solidification agent. After the injection tool 4 has passed the loosened area 10, which is now stabilized by solidifying solidifying agent, the injection tool 4 can again stop dispensing solidifying agent. After the drill rod 3 has been completely pulled out with the injection tool 4, the pilot hole 8 is present. This can be reamed to create a larger diameter hole that is used to route cables.

4 shows the sequence of a method 11 according to the invention in a block-based representation. First, a pilot drill head 2 is arranged on a drill rod 3 at a starting point 1 in the ground 7 12. The pilot drill head 2 is then placed in the ground 7 on a predefined path from the starting point 1 to an end point 5 for producing a pilot hole 8 out and driven 13. The pilot drill head 2 or the drill string 3 is coupled to an injection tool 4 and the injection tool 4 is guided through the pilot hole. This can be done when the drill string 3 is pulled back 15 to the starting point 1 . At least in certain areas, a solidifying agent is applied 16 to the adjoining soil 7 to solidify the soil 7. In this case, sealing elements could separate 18 partial regions into which the solidifying agent is introduced. The strength of the soil may be analyzed 17 before or during the drilling of the pilot hole. This could include, for example, examining washed-out material. After the pilot hole 8 has been created, the pilot hole 8 can be broached 19 in order to pull in a line.

The invention is not limited to one of the embodiments described above, but can be modified in many ways.

All of the features and advantages resulting from the claims, the description and the drawing, including structural details, spatial arrangements and method steps, can be essential to the invention both on their own and in a wide variety of combinations.

Reference List

1

starting point

2

pilot drill head

3

drill pipe

4

injection tool

5

end point

6

horizontal drilling machine

7

floor

8th

pilot hole

9

injection port

10

Area of loose soil around a borehole

11

proceedings

12

Arrange pilot drill head at starting point

13

Lead and drive

14

Pair with injection tool

15

retraction of the drill pipe

16

Application of solidification agent

17

Analyzing the soil

18

Separation of sub-areas

19

Clearing the pilot hole

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• EP 2863003 A2 [0003]
• DE 19808478 C2 [0007]
• WO 2015197828 A1 [0008]

Claims (15)

Method (11) for preparing or producing a borehole in a ground (7) for laying a line in the borehole, comprising the steps of: arranging (12) a pilot drill head (2) arranged on a drill rod (3) at a starting point (1) in the ground (7), driving and guiding (13) the pilot drill head (2) in the ground (7) on a predefined path from the starting point (1) to an end point (5) for producing a pilot bore (8), and retracting ( 15) of the drill string (3) to the starting point (1), characterized by the step of guiding (14) coupled with a movement of the pilot drill head (2) or the drill string (3) an injection tool (4) through the pilot bore (8), which applying (16) at least some areas of a consolidating agent to the adjoining soil (7) to consolidate the soil (7). Method (11) according to claim 1 , characterized in that an aqueous bentonite or cement suspension, a reaction resin curing by polymerisation or a physically setting adhesive or mixtures of the aforementioned compounds is used as the strengthening agent, preferably a reaction resin based on acrylate or silicate resin or a reaction resin based on polyurethane. Method (11) according to claim 1 or 2 , characterized in that the injection tool (4) is coupled at the end point (5) to the pilot drill head (2) or the drill pipe (3) and when the drill pipe (3) is pulled back to the starting point (1) the solidifying agent is selectively deployed (16) . Method (11) according to claim 1 or 2 , characterized in that the injection tool (4) is moved when producing the pilot bore (8) with the pilot drill head (2) and thereby selectively discharges the solidifying agent (16). Method (11) according to one of the preceding claims, characterized in that the solidifying agent is injected radially from the injection tool (4) onto the surrounding soil (7). Method (11) according to one of the preceding claims, characterized in that the strength of the base (7) is analyzed (17) before or during the production of the pilot bore (8). Method (11) according to claim 6 , characterized in that when the pilot bore (8) is made, the condition of the washed-out material is examined in order to analyze (17) the strength of the soil (7). Method (11) according to claim 6 or 7 , characterized in that the injection tool (4) discharges (16) the solidifying agent in areas (10) of the pilot bore (8) in which the strength is below a desired minimum strength. Method (11) according to one of the preceding claims, characterized in that when the consolidating agent is discharged, at least a partial area of the pilot bore (8) is separated from adjacent areas (18) and the consolidating agent is discharged exclusively in the partial area for consolidating the soil (7). (16). Method (11) according to claim 9 , characterized in that several partial areas of the pilot bore (8) are solidified. Method (11) according to claim 9 or 10 , characterized in that two sealing elements spaced apart from one another along the pilot bore (8) are expanded to separate a respective partial area and are contracted after the solidifying agent has been discharged. Method (11) according to claim 11 , characterized in that after the contraction, the partial area containing the solidifying agent is radially compressed by means of the sealing elements. Method (11) according to one of the preceding claims, characterized in that after the pilot drill head (2) and the drill rod (3) have been completely withdrawn, the pilot bore (8) is cleared and the line is pulled in. Use of a solidifying agent discharged into the surrounding soil (7) of a pilot bore (8) produced by a horizontal drilling method for solidifying the pilot bore (8). use after claim 15 , wherein the solidifying agent is discharged in situ when the pilot bore (8) is made or when a pilot drill head (2) is withdrawn.

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