Method for preparing or making a bore in a floor

Abstract

A method for preparing or creating a borehole in soil for laying a pipe in the borehole comprises the steps of positioning a pilot drill head attached to a drill string at a starting point in the soil, driving and guiding the pilot drill head in the soil along a predefined path from the starting point to an endpoint to create a pilot borehole, and retracting the drill string with the pilot drill head to the starting point. According to the invention, the step of guiding an injection tool through the pilot borehole, coupled with a movement of the pilot drill head, is provided. This injection tool injects a soil stabilizer, at least in certain areas, into the adjacent soil to stabilize the soil.

Description

[0001] The invention relates to a method for preparing or producing a borehole in a ground according to the preamble of claim 1. In particular, the method can be used as preparation for laying a line in the borehole.

[0002] Horizontal drilling methods are commonly used for laying cables, such as pipelines, conduits, or electrical lines, underground. Instead of digging a trench, they create a substantially horizontal borehole for the cables to pass through. The horizontal directional drilling (HDD) method is particularly frequently used.

[0003] As described, for example, in EP 2 863 003 A2, to install the new pipeline in the ground, an initial pilot bore is first drilled into the ground between a starting point and a target point. For this purpose, a starting pit is created at a starting point, and a pilot drill head is inserted into the ground within this starting pit. A target pit is provided at the intended target point, into which the pilot drill head exits.

[0004] The pilot drill head is preferably mounted on a drill rod, which is extended in sections and continuously guided into the borehole during drilling. The course and direction of the pilot hole can be controlled by influencing the pilot drill head. After drilling the pilot hole, the pilot drill and the drill rod are retracted from the borehole and returned to the starting point.

[0005] The pilot hole can then be reamed using a reamer to expand it to a diameter that corresponds to the outer diameter of the pipe to be installed. Before the reamer is retracted, the pipe to be installed is attached to the drill head, and the pipe is pulled into the expanded hole as the reamer is withdrawn.

[0006] Due to varying geological conditions in the soil, the borehole may partially collapse or collapse during retraction of the pilot drill head and / or the reamer, for example, in sandy or gravel-filled soil sections. However, if the pilot borehole is already blocked due to collapsed sections of the borehole, the subsequent reamer drilling cannot be carried out, and the pipeline to be laid cannot be pulled in.

[0007] DE 198 08 478 C2 also uses horizontal drilling technology to initially create a pilot bore. Once this is completed, a special drilling machine is deployed. This machine is equipped with a cutting disc, a cutting wheel, or a drill head, and can crush larger stones with the help of an integrated crushing tool. The drilling machine is inserted at the end point of the pilot bore and expands the pilot bore to the required diameter. At the same time, the pipeline to be laid is pulled into the borehole with the drilling machine. Here, too, there is a risk that when the pilot drill is withdrawn, the ground will collapse at least in part due to the geological conditions, preventing the pipeline from being pulled in.

[0008] From WO 2015 197 828 A1 a method for creating a borehole in a ground and for laying a pipeline in the borehole is known, in which a combination of an outer pipe and an inner pipe is used, wherein the outer pipe and a drill head coupled to the inner pipe are driven separately in order to achieve greater ranges due to better kink resistance.

[0009] US 2010 / 181110 A1 describes a process in which a consolidation fluid is introduced into a borehole.

[0010] EP 2 447 462 A1 describes a method for the underground installation of a pipeline between a start page and a target page.

[0011] DE 197 29 809 C1 describes a drilling device with a pilot drill head which has outlet openings for a stiffening drilling suspension.

[0012] The aim of the invention is to overcome the described disadvantages of the prior art and to create a method with which a borehole through the subsoil can be produced in a stable manner, so that in particular a pipeline to be laid can always be laid quickly and reliably in the ground.

[0013] Main features of the invention are set out in claim 1.

[0014] 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 pilot drill head arranged on a drill rod 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 end point to produce a pilot bore, and retracting the drill rod to the starting point.According to the invention, the step of guiding an injection tool through the pilot bore coupled to a movement of the pilot drill head or the drill rod is provided, which injection tool applies a consolidation agent to the adjacent soil in certain areas to consolidate the soil, wherein the pilot drill head is driven completely through the soil to the end point and the injection tool is then coupled to the pilot drill head or the drill rod at the end point and, when the drill rod is retracted to the starting point, selectively applies the consolidation agent only in certain areas in the pilot bore.

[0015] Depending on the pressure applied and the soil conditions, the consolidation agent can be pressed deeper or deeper into the soil surrounding the borehole. Injection materials are used as consolidation agents, which harden after injection.

[0016] 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. Alternatively or additionally, impacting the pilot drill head is also conceivable. Known sensor technology can be used to determine the current position of the pilot drill head and influence the corresponding control of the drilling mechanism to follow the predefined path. The method according to the invention therefore begins with a controllable horizontal drilling process for creating a continuous pilot bore between the starting point and the end point.

[0017] According to the invention, the pilot bore is stabilized by an injection tool that is guided through the pilot bore. The injection tool is guided in conjunction with a movement of the pilot drill head or drill rod. This means that while the drill rod of the pilot drill head is still in the pilot bore, the injection tool is guided in the pilot bore.

[0018] In a preferred embodiment, an aqueous bentonite or cement suspension, a polymerization-curing reactive resin (chemically curing adhesive), or a physically curing adhesive (e.g., solvent-based adhesives) is used as the solidifying agent. Polymerization, as a generic term, encompasses polyaddition, polycondensation, and radical polymerization, i.e., a reactive resin that cures by polyaddition, polycondensation, or radical polymerization can be used as the solidifying agent. Preferably, a reaction compound based on acrylate or silicate resin, or a reaction compound based on polyurethane, is applied to the area surrounding the drilled borehole.

[0019] The injection tool is intended to be coupled to the pilot drill head at the end point or, if necessary after detaching the pilot drill head, to the drill rod. Upon retracting the drill rod to the starting point, the injection tool selectively applies the stabilizing agent. Consequently, the pilot drill head is driven completely through the ground to the intended end point and then protrudes from the second pit located there. The injection tool can then be connected to the pilot drill head or, after detaching the pilot drill head, directly to the drill rod. In this case, a non-rotational connection to the pilot drill head can be provided so that the injection tool does not twist.

[0020] In a particularly advantageous embodiment, the solidifying agent is sprayed radially (with respect to the central axis of the borehole) from the injection tool onto the surrounding soil. The application can be distributed around the entire circumference, so that a closed, tubular shell of solidifying agent is formed. Alternatively, the application can be selectively carried out only in a desired region of the circumference, so that, for example, only a half-shell or another segment of a shell of solidifying agent is formed if solidification of the soil around the borehole is only desired there. The injection tool can therefore have nozzles, openings and / or slots distributed around the circumference of the injection tool and through which the solidifying agent is applied radially onto the surrounding soil. The drill rod can provide the necessary conduits for the solidifying agent and other things.In the case of very loose subsurface areas where there is a risk of collapse immediately after the borehole has been created, it may be necessary to inject a larger amount of stabilizing agent into the soil in front of the pilot drill bit, thereby consolidating a zone whose diameter exceeds the diameter of the borehole to be created. This consolidated zone is then drilled through, leaving consolidated areas around the borehole. In these cases, the injection tool can be equipped with a line running close to or through the pilot drill bit, allowing the stabilizing agent to be injected into a zone located in front of the pilot drill bit in the direction of drilling.

[0021] In principle, a distinction can be made between injections of stabilizing agent into the borehole area that follow, parallel, or lead the borehole in relation to its creation. The term “lagging” refers to injections that occur when the injection tool follows the pilot drill bit at some distance or is only pulled through the created borehole when the drill rod is withdrawn. This type of procedure is applicable when the soil surrounding the borehole has a certain basic strength, so that it can be assumed that the borehole will be stable for at least a certain time until the injection tool is guided through the borehole. Parallel or simultaneous injections are those that occur when an injection tool follows immediately after the tip of the pilot drill bit or at a very short distance behind it and injects stabilizing agent into the borehole section that is just being created.In this case, the injection direction is primarily radial, i.e. the stabilizing agent is pressed into the soil surrounding the borehole perpendicular to the drilling direction and rotating 360° around the axis of the drilling direction. With such an injection parallel or simultaneous to the drilling process, a section of the borehole is stabilized by hardening stabilizing agent practically as it is created. With advance or leading injection, stabilizing agent is pressed into the area in front of the pilot drill head in the drilling direction, and the soil in the borehole area is thus stabilized by hardened stabilizing agent even before it is created. As already mentioned, this procedure is recommended in very loose areas where a borehole would otherwise be filled in immediately or after a short time.For such advance injection, the injection tool can have lines or lances that are positioned, at least temporarily, to run close to or through the pilot drill bit, with their injection opening directed toward the area in front of the pilot drill bit. Several of these three injection methods can also be combined.

[0022] In the case of consecutive or parallel injection, the chemical formulation of the hardening agent must be adapted to the movement of the injection tool through the borehole so that the injection tool has already left the area where the hardening agent has been injected before the hardening agent has completely hardened. This prevents the hardened hardening material from hardening on the injection tool and being pulled along with it.

[0023] Furthermore, the soil strength could be analyzed before or during the pilot borehole drilling. This analysis could be performed using probes inserted into the soil from outside. Alternatively, a sensor system could be installed directly inside the pilot borehole, allowing the soil to be examined during or immediately after the drilling.

[0024] During the pilot bore, the quality of the excavated material could be examined to analyze the soil's strength. Consequently, the soil's quality is continuously examined to assess its strength.

[0025] The injection tool could inject the stabilizing agent into areas of the pilot bore where the strength is below a desired minimum. The areas where the soil strength is insufficient to ensure the stability of the pilot bore could, for example, be electronically stored, allowing them to be subsequently stabilized one after the other under the control of a control unit.

[0026] It is advantageous if, during the discharge of the stabilizing agent, at least one section, i.e., a lengthwise portion, of the pilot bore is separated from adjacent sections, and the stabilizing agent is discharged exclusively in the section for soil stabilization. This allows the stabilizing agent to be discharged by means of overpressure in the corresponding section, so that individual sections can be efficiently solidified and the stabilizing agent does not flow into adjacent sections of the pilot bore.

[0027] It is also conceivable that several sections of the pilot bore are consolidated. The sections could, for example, be adjacent to one another or spaced apart. It may be advisable to provide two opposing axial boundaries of a section at a constant distance, allowing larger sections to be consolidated, for example, by sequentially treating several smaller sections with fixed dimensions. This limits the size of the injection tool, and consistent flow conditions can be guaranteed in the defined sections.

[0028] It is advantageous to expand two sealing elements spaced apart along the pilot bore to separate a respective section and to contract them after the solidifying agent has been discharged. The sealing elements could be, for example, fluid-inflatable, ring-shaped, cushion-like devices that can be selectively expanded and contracted. The use of a soft, elastic material allows for a good seal against the ground.

[0029] After contraction, the section containing the strengthening agent could be radially compressed using the sealing elements. It might be advisable to partially compress the soil radially using these sealing elements to achieve particularly good consolidation.

[0030] After the pilot drill head and drill rod have been fully retracted, the pilot hole can be cleared and the pipe pulled in. This completes the installation of the pipe through the hole in the ground.

[0031] The invention further relates to the use of a consolidation agent discharged into the surrounding soil of a pilot borehole produced by a horizontal drilling method for consolidating a pilot borehole.

[0032] The hardening agent could be discharged in situ during the creation of the pilot hole or during the retraction of a pilot drill head.

[0033] Further features, details, and advantages of the invention will become apparent from the wording of the claims and from the following description of exemplary embodiments with reference to the drawings. They show: Fig. 1 shows a schematic cross-section of the subsoil after drilling the pilot bore, Fig. 2 shows the schematic cross-section during coupling of the injection tool, and Fig. 3 shows the cross-section during consolidation of a loose area of ​​the soil around the borehole. Fig. 4 shows a block-based, schematic representation of the process.

[0034] In Fig. 1 A schematic cross-section through an underground area is shown, through which a horizontal drilling machine 6 has created a pilot bore 8. This extends from a starting point 1 in front of the horizontal drilling machine 6 to an end point 5. For this purpose, a pilot drill head 2 can be guided through the ground on a drill rod 3 along a desired path. The pilot bore 8 leads, for example, through a ground area 10 with loosened soil.

[0035] After creating the pilot hole 8 as in Fig. 1As shown, the pilot drill head 2 protrudes from the ground at the end point 5. The drill rod extends through the entire pilot bore 8, thereby preventing the adjacent soil from collapsing. An injection tool 4 is then coupled to the pilot drill head 2; alternatively, the pilot drill head 2 can be detached from the drill string and, as shown in Fig. 2 As shown, an injection tool 4 can be coupled directly to the drill rod 3.

[0036] The injection tool 4 is in Fig. 2schematically depicted as a cylindrical body having an internal cavity communicating with a series of injection openings 9 on the surface of the injection tool 4. The injection openings 9 are preferably arranged distributed around the circumference of the injection tool 4 and are designed to be able to deliver a solidifying agent. The drill rod 3, with the injection tool 4 arranged thereon, is retracted through the pilot bore 8, with the solidifying agent being delivered in certain areas where it is needed during the retraction.

[0037] In particular, when the injection tool 4 reaches the loose area 10 during retraction, the solidifying agent is pressed under pressure into the injection tool 4 and thereby pressed out of its injection openings 9 into the surrounding soil. This is Fig. 3shown. If the injection openings 9 are distributed accordingly around the circumference of the injection tool 4, a closed, tubular shell of the solidifying agent is created. After the injection tool 4 has passed through the loosened area 10, which is now stabilized by the solidifying agent, the application of solidifying agent by the injection tool 4 can be stopped. After the drill rod 3 has been completely withdrawn with the injection tool 4, the pilot bore 8 is created. This can be expanded to create a bore of larger diameter, which is used for laying cables.

[0038] Fig. 4shows in block-based representation the sequence of a method 11 according to the invention. First, a pilot drill head 2 is arranged 12 on a drill rod 3 at a starting point 1 in the ground 7. Subsequently, the pilot drill head 2 is guided and driven 13 in the ground 7 on a predefined path from the starting point 1 to an end point 5 to create a pilot bore 8. The pilot drill head 2 or the drill rod 3 is coupled to an injection tool 4, and the injection tool 4 is guided through the pilot bore. This occurs when the drill rod 3 is retracted 15 to the starting point 1. .

[0039] A stabilizing agent is applied 16 to the adjacent soil 7 in certain areas to stabilize the soil. Sealing elements could separate 18 sections into which the stabilizing agent is introduced. The strength of the soil can be analyzed 17 before or during the creation of the pilot bore. This could, for example, include examining the eluted material. After the creation of the pilot bore 8, the pilot bore 8 can be cleared 19 to allow the insertion of a pipe. List of reference symbols

[0040] 1Starting point 2Pilot drill bit 3Drill rod 4Injection tool 5Ending point 6Horizontal drilling machine 7Soil 8Pilot bore 9Injection opening 10Area with loose soil around a borehole 11Procedure 12Positioning the pilot drill bit at the starting point 13Guiding and driving 14Coupling with the injection tool 15Retracting the drill rod 16Applying the stabilizing agent 17Analyzing the soil 18Separating sections 19Clearing the pilot bore

Claims

1. Method (11) for preparing or producing a bore in the ground (7) for the purpose of laying a line in the bore, comprising the steps of: arranging (12) a pilot drilling head (2), which is on a drill string (3), at a starting point (1) in the ground (7), driving and guiding (13) the pilot drilling head (2) in the ground (7) on a predefined path from the starting point (1) to an end point (5) to produce a pilot bore (8), drawing back (15) the drill string (3) to the starting point (1), and the step of guiding (14), coupled with a movement of the pilot drilling head (2) or of the drill string (3), an injection tool (4) through the pilot bore (8), the injection tool in certain regions discharging (16) a consolidating agent into the adjacent ground (7) to consolidate the ground (7), wherein the pilot drilling head (2) is driven all the way through the ground to the end point (5) and the injection tool (4) is subsequently coupled to the end point (5) by means of the pilot drilling head (2) or the drill string (3) and, when the drill string (3) is being drawn back to the starting point (1), selectively discharges (16) the consolidating agent only in certain regions in the pilot bore.

2. Method (11) according to Claim 1, characterized in that the consolidating agent used is an aqueous bentonite or cement suspension, a polymerization-curing reactive resin, or a physically setting adhesive or mixture of the aforesaid compounds, preferably a reactive resin based on acrylate resin or silicate resin or a reactive resin based on polyurethane.

3. Method (11) according to either of the preceding claims, characterized in that the consolidating agent is sprayed radially from the injection tool (4) onto the surrounding ground (7).

4. Method (11) according to one of the preceding claims, characterized in that the firmness of the ground (7) is analysed (17) before or during the production of the pilot bore (8).

5. Method (11) according to Claim 4, characterized in that, on production of the pilot bore (8), the condition of deposited material is investigated in order to analyse (17) the firmness of the ground (7).

6. Method (11) according to Claim 4 or 5, characterized in that the injection tool (4) discharges (16) the consolidating agent in regions (10) of the pilot bore (8) that have a firmness below a desired minimum firmness.

7. Method (11) according to one of the preceding claims, characterized in that, on discharge of the consolidating agent, at least a sub-region of the pilot bore (8) is isolated (18) from adjacent regions and the consolidating agent is discharged (16) exclusively in the sub-region to consolidate the ground (7).

8. Method (11) according to Claim 7, characterized in that multiple sub-regions of the pilot bore (8) are consolidated.

9. Method (11) according to Claim 7 or 8, characterized in that two sealing elements spaced apart from one another along the pilot bore (8) and intended for isolating a respective sub-region are expanded and, after discharge of the consolidating agent, contracted.

10. Method (11) according to Claim 9, characterized in that, after the contraction, the sub-region comprising the consolidating agent is radially compressed by means of the sealing elements.

11. Method (11) according to one of the preceding claims, characterized in that, after the pilot drilling head (2) and the drill string (3) have been drawn all the way back, the pilot bore (8) is cleared and the line is drawn in.

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