HORIZONTAL DRILLING METHOD AND HORIZONTAL DRILLING SYSTEM

Description

Field of the invention

[0001] The invention relates to a horizontal drilling method according to the preamble of claim 1 and a horizontal drilling system according to the preamble of claim 14. State of the art

[0002] The standard method in civil engineering for drilling boreholes for laying underground pipelines with a diameter of up to 1000 mm is the horizontal directional drilling method. Since this method avoids the need to excavate a trench, it is particularly suitable for crossing under flowing waterways, roads, highways, etc.

[0003] The horizontal directional drilling rig uses a drill bit to drill a pilot bore from a starting pit toward the target pit. The drill bit is bolted to the drill string, which is assembled from piecemeal drill rods and driven into the ground by the horizontal directional drilling rig. The drill string, which is smaller in diameter than the drill bit, leaves an annular space. A bentonite drilling fluid is pumped through the rod to the drill bit, where it exits and flushes the cuttings through the annular space. In addition to flushing out cuttings, the drilling fluid also supports the borehole and seals the borehole wall. Due to the special properties of bentonite, it also serves to cool the drill bit and act as a lubricant.

[0004] Once the drill bit has reached the target pit, it is replaced with a reamer. The reamer has a larger diameter than the drill bit and, as it is retracted, expands the pilot hole while simultaneously compacting the bore walls. Depending on the soil conditions, more cuttings are removed or displaced. Attached to the reamer, either another drill string can be pulled into the bore channel for further expansion steps, or one or more pipes can be pulled into the bore channel.

[0005] US 5 979 574 A, US2018 / 163475 A1, US 9 828 805 B2 and DE 297 03 655 U1 describe such a horizontal directional drilling method.

[0006] However, there are certain geological soil compositions where horizontal directional drilling is unsuitable for creating a breakthrough. This is particularly the case when the soil is unstable and there is a risk of settlement after drilling. It is also possible that the soil immediately shrinks the breakthrough after drilling, so that the forces on the reamer are too great to guide it through the breakthrough, or the borehole collapses, making pipe pulling impossible.

[0007] To consolidate the borehole, DE 297 03 655 U1 proposes incorporating an elastomeric molded body into the drill rod. The molded body compacts the soil around the expanded borehole wall. Object of the invention

[0008] The disadvantages of the described state of the art give rise to the task of demonstrating a horizontal drilling method that can also be used in the unstable ground conditions described above. Description

[0009] The stated problem is solved in a horizontal drilling method by the features stated in the characterizing portion of patent claim 1. Further developments and / or advantageous embodiments are the subject of the dependent patent claims.

[0010] The invention is characterized by the integration of at least one jet grouting element (DSE) into the drill string, with which DSE binder introduced into the drill string is injected into the soil surrounding the borehole using a jet grouting process before step 3) or during step 1), thereby creating a binder column around the borehole. The method enables horizontal drilling in unstable soil, which is not possible with prior art methods. With the known methods, the borehole becomes unstable in such soils or, in the worst case, collapses. Unstable soils that are unsuitable for prior art methods but into which a stable borehole can be drilled using the present method contain, for example, Rhine gravel or coarse gravel without a significant fine grain content.The method allows for the creation of a substantially horizontal borehole even in unstable soil without the risk of subsidence. Subsidence at the surface of the soil is thus avoided. Because the underlying soil is saturated by the binder column, groundwater cannot erode or destabilize the soil around the borehole. If the soil stability permits, at least one DSE can be inserted between the drill head and the drill rod. This allows steps 1) and 2) to be performed simultaneously.

[0011] It has proven to be effective when the jet grouting method is either high-pressure injection (HPI) or low-pressure injection (LPI). To build a stable binder column, the grain structure of the existing soil must be cut open. This is achieved by the jet grouting at pressures of up to 750 bar. If the soil is such that the drill bit can cut open the grain structure, LPI can be used, which uses pressures of only up to 250 bar. This allows the appropriate jet grouting method to be selected depending on the soil conditions.

[0012] The binding agent is preferably a cement suspension. This suspension penetrates the soil and, together with the cut-open grain structure, forms a stable binding agent column around the borehole.

[0013] In a particularly preferred embodiment of the invention, a plurality of jet grouting elements are integrated one after the other into the drill rod, and the opening and closing of the nozzles of a DSE is controlled via the first end of the drill rod, which is free from the binder supply line. An existing drilling system can therefore be supplemented with the special DSE with little effort. These simply need to be screwed between two drill rods. Any existing end of the drill rod can be used to enable the continuous and uninterrupted production of the binder column. If a DSE fails, for example, because a nozzle is clogged, another DSE can be used at any time.

[0014] It is advantageous to provide a coupling element between the second end of the drill rod, where the binding agent is introduced, and the binding agent supply line from a mixing plant. The coupling element allows the drill rod to rotate within this coupling element. The coupling element establishes the connection between the rigid binding agent supply line and the rotating drill rod.

[0015] The invention is also preferably characterized in that the drill rod is moved and rotated back and forth over a distance of no more than 7 m during the hardening period of the binder. During the hardening period of the binder column, the drill rod cannot adhere to the binder and can continue to be rotated and rotated after the hardening period.

[0016] To prevent adhesion to the binder, removal blades are provided at the coupling ends of the pipe rods. These remove binder along the entire length of the borehole during the curing period. This gradually "cuts free" the drill rod, allowing it to remain mobile at all times.

[0017] In a further preferred embodiment of the invention, the borehole is widened with a reamer after step 1) and flushed with bentonite. This allows dense and saturated soil, into which no binder can be injected in the first place, to be loosened and flushed out with bentonite. This creates space in the existing soil for the binder.

[0018] It is advisable to inspect and clean the borehole after steps 3 or 4. This step is called a "clean pass." This can prevent a product pipe from becoming stuck during retraction or detect other defects in the borehole.

[0019] It is advantageous if, after steps 3) or 4), a product pipe is pulled into the borehole using the drill rod. This allows the drilling method to be used for pipelaying with all the advantages of horizontal directional drilling, but also in unstable soils.

[0020] The borehole is best inspected and cleaned by pulling a product pipe no longer than 5 m through the borehole. If this test pipe can be pulled completely through the borehole, it can be assumed that the entire product pipe can also be pulled into the borehole. In addition, the test pipe can remove contaminants from the borehole.

[0021] By filling the void between the binder column and the product pipe with a filler material, settlement in the soil and on the surface can be reliably prevented. However, such settlement is very unlikely, as the binder column is already very stable and resistant to settlement.

[0022] In a preferred embodiment for constructing a tunnel, a plurality of boreholes are drilled along a tunnel arch, the binder columns of which touch each other. The soil within the tunnel arch is removed, the tunnel arch is reinforced with anchors penetrating the binder columns, and the tunnel arch is lined with shotcrete. Thus, using the present horizontal boring method, a tunnel with a length of up to 1 km can be constructed with minimal effort. A tunnel boring machine, which is very expensive to manufacture and operate, is eliminated.

[0023] In a preferred embodiment for soil stabilization beneath a settled object, particularly a building, a borehole and a binder column are created, a strand is pulled into the borehole, the strand is tensioned and anchored at both ends, and the remaining cavity in the borehole is filled with a filler material. This allows the settlement of the soil beneath a building to be halted with minimal effort, preventing further subsidence of the building.

[0024] A further aspect of the invention relates to a horizontal drilling system for carrying out a horizontal drilling method according to the above description and according to the preamble of claim 14. The invention is also characterized in that at least one DSE with at least one nozzle on its casing, and preferably several interconnected DSEs, can be arranged between two adjacent drill rods, wherein one of the drill rods serves to control the closure or opening of the nozzles via the first end of the drill rod, and the other drill rod serves to supply the DSE with binding agent via the second end of the drill rod. This allows the existing drill rod to be optimally used for operating the HDI or NDI. In addition, the failure of one DSE can be immediately compensated for by commissioning another DSE. The time-consuming removal of the drill rod and the replacement of the defective DSE with a functioning DSE can thus be avoided.

[0025] In a further preferred embodiment of the invention, removal wings are formed on the coupling ends of the drill rods, the circumferential circle of which has a larger diameter than the respective coupling end. This allows the drill rod to be cut free by continuous rotation while the binder column hardens.

[0026] The system for supplying the binding agent from a mixing plant preferably includes a coupling element through which the binding agent is introduced into the second end of the drill rod and within which the drill rod can rotate in a sealed manner. The coupling element establishes a connection between the stationary binding agent supply line and the rotating drill rod.

[0027] Further advantages and features will become apparent from the following description of several embodiments of the invention with reference to the schematic representations. The following schematic diagrams are not drawn to scale: Figure 1: Creating a pilot bore; Figure 2: Creating a binder column; Figure 3: Waiting for the hardening time; Figure 4: Enlarging the borehole; Figure 5: Checking and cleaning the borehole; Figure 6: Pulling in the product pipe; Figure 7: Filling the cavity around the product pipe; Figure 8: Simultaneous creation of the pilot bore and the binder column; Figure 9: Enlarging the borehole after creating the pilot bore; Figure 10: Arrangement of several jet grouting elements (Detail X); Figure 11: Introducing the binder (Detail Y); Figure 12: Drill rod detail with removal blades (Detail Z); Figure 13: Tunnel with multiple boreholes with binder column Figure 14: Excavated tunnel Figure 15: Reinforced tunnel arch Figure 16: Pilot borehole under a set building Figure 17: Borehole with a laid strand and Figure 18 Strand in the filled borehole

[0028] In the Figures 1 to 10 and 13 to 18a borehole is shown, which is designated overall by the reference numeral 11. The borehole 11 is created without the need to dig a trench, since a horizontal drilling method is used. To create the borehole 11, a pilot hole is drilled. For this purpose, a drill head 13 is driven into the ground at the tip of a drill rod 15. The drill rod 15 is created by a plurality of drill rods 17 coupled to one another. The facing sides of adjacent drill rods 17 can, for example, be screwed into one another. For this purpose, one drill rod has an external thread 19 and the other drill rod an internal thread 21. The respective direction of displacement of the drill rod 15 is indicated in the figures by an arrow.

[0029] A drilling rig 23 sets the drill rod 15 and the drill head 13 in rotation, whereby the drill head is driven from a starting pit 25 towards a target pit 27. The drill rod 15 is successively extended by another drill rod 17 until the drill head 13 reaches the target pit 27. During the drilling process, bentonite is introduced into the drill rod 15, which cools and lubricates the drill head 13 and flushes the drilling cuttings out of the borehole. The emerging drilling fluid is enriched with drilling cuttings and collects in the starting pit, from where it is pumped back to the mixing plant via the recycling plant. In a recycling plant 29, the discharged drilling cuttings are separated from the bentonite fluid so that the drilling fluid can be reused. This first process step is described in Figure 1 shown.

[0030] If the geology of the soil into which borehole 11 is being drilled is unstable, the application of the conventional horizontal directional drilling technique is not possible because the borehole is unstable. For example, the occurrence of Rhine gravel in the soil leads to such unstable conditions.

[0031] In order to make the borehole stable, the following process step is carried out: After the drill head 13 has reached the target pit, it is removed and at least one jet grouting element (DSE) 31 is coupled to the drill rod 15. This arrangement is shown in detail X in Figure 10shown. Each DSE 31 has at least one nozzle 33 and an external thread 19 or an internal thread 21 at its ends. This allows each DSE 31 to be connected to a drill rod 17 or to another DSE 31. In such an arrangement, the drill rod has a first end 35 and a second end 37. A binder is introduced into the drill rod 15 and the DSE 31 via the second end 37. The binder is preferably a cement suspension. The binder is mixed with the existing soil via the nozzles 33 of a DSE 31, whereby a binder column 39 hardens around the borehole 11 and stabilizes the borehole 11. For reasons of redundancy, several DSE 31s are arranged one behind the other. If the nozzles 33 of one DSE 31 become blocked, another DSE 31 with functioning nozzles 33 can be put into operation. The opening and closing of the nozzles 33 of a DSE 31 is done via a valve 41.The valve 41 is controlled, for example, via a control line, compressed air, a radio signal, mechanically, or a retraction movement. The control line can be implemented via the first end 35 in the drill rod 15. The valve 41 can receive compressed air if a flap 42 is opened on the drill rod 17 connected to the DSE 31. Thus, if a nozzle 33 becomes clogged in the middle of the borehole 11, the drill rod 15 does not have to be completely pulled out of the borehole, but another DSE 31 can be activated. A nozzle 31 has a diameter of 2.5 to 6 mm.

[0032] The DSE 31 are pulled from the target pit 27 into the starting pit 25 ( Figure 2). Once the DSE 31 has reached the starting pit 25, the entire borehole is reinforced with a binder column 39. Settlement of the soil and the surface is therefore reliably prevented by the binder column 39. Furthermore, the soil where the borehole 11 is located is saturated with the binder, and groundwater can no longer penetrate the soil and distort or erode it.

[0033] In order to feed the binding agent into the rotating drill rod 15, a coupling element 43 is provided, which is shown in detail Y in Figure 11 The binder is provided in a mixing system 45 with cement from a silo 47 and water as a suspension. The coupling element 43 enables the binder to be introduced from the mixing system 45 through the fixed supply line 49 into the rotating drill rod 15 by allowing the drill rod 15 to rotate in the coupling element 43.

[0034] Depending on the existing soil conditions, the jet grouting process can be a high-pressure injection (HPI) or a low-pressure injection (LPI). With HPI, the binder is injected into the existing soil at pressures of up to 550 bar. Due to the high pressure, the jet stream cuts open the soil grain structure and mixes it with the binder. HPI can be performed in a single-, two-, or three-phase process. The binder can therefore be injected alone, with air or water, or with air and water.

[0035] If the soil conditions are such that the drill bit can cut through the grain structure, NDI can also be used. For NDI, a maximum pressure of 200 bar is sufficient, making this method more cost-effective.

[0036] Since the binder column 39 must harden, the drill rod must remain in the borehole for up to 24 hours. To prevent the drill rod from sticking to the binder 39 during this time, the drill rod 15 is constantly rotated and moved back and forth linearly by up to 7 m. Removal wings 51 are formed on the coupling ends 50 of the drill rods 17 (see detail Z shown in Figure 12 ). The removal blades 51 can cut the drill rods 17 free from the binding agent by rotating the drill rod 15.

[0037] The now hardened borehole can be widened in one or more stages. For this purpose, a reamer 52 is integrated into the drill rod 15 and pulled through the borehole 11. If necessary, this process can be repeated with additional reamers 52 of larger diameter. This allows boreholes 11 with a borehole diameter of up to 100 cm to be created ( Figure 4 ).

[0038] To inspect and clean the finished borehole 11, a control reamer can be pulled through the borehole 11. It is also conceivable to pull a section of the product pipe 53, which will be laid later, with a length of, for example, 5 m through the borehole 11. If this section can be pulled through the borehole, it can be assumed that the product pipe 53 can be pulled into the borehole over the entire length of the borehole 11. Figure 5 the borehole 11 is shown, which is now cleaned and inspected and is ready for the insertion of the product pipe 53.

[0039] In Figure 6The pulling-in of the product pipe 53 is shown. Due to the presence of the binder column 39 and its stabilization of the borehole 11, the product pipe 53 does not have to be pulled in as quickly as is necessary with prior art methods. Rather, the pulling-in process can be interrupted, and there is no time pressure when welding the individual product pipe sections. Therefore, the product pipe 53 does not have to be fully designed and ready for pulling-in once the borehole 11 is completed. The product pipe 53 can be a protective pipe for other pipes, cables, or a district heating line. However, it can also be the direct carrier pipe, e.g., of a water or gas line.

[0040] To ensure that no settlement occurs, the cavity 55 between the binder column 39 or the borehole 11 and the product pipe 53 is filled with a filling material 54. For this purpose, as in Figure 7shown, the filling material 54 is pumped into the cavity 55 by a pump 57.

[0041] In Figure 8 An embodiment of the method is shown which can be applied under safe geological conditions. Bentonite flushing during drilling of the borehole can be omitted, and the injection of binder after the HDI or NDI can take place during drilling. This allows two work steps to be performed simultaneously, resulting in significant time savings. To carry out this embodiment, a plurality of DSE 31s can be coupled directly to the drill head 13, and the drill rod 15 can be coupled to the last DSE 31. The resulting drilling cuttings can be split by the HDI and therefore do not need to be removed from the borehole.

[0042] The embodiment according to the Figure 9is used when the soil is extremely dense and saturated. A reamer 52 is pulled through the borehole 11 several times on the drill rod 15, and the area surrounding the borehole 11 is repeatedly flushed with bentonite. This creates space in the soil or loosens it, allowing the binding agent to be injected into it.

[0043] In the Figures 13 to 15 An application of the horizontal boring method described above is shown to create a tunnel 60: A plurality of boreholes 11 are drilled and binder columns 39 are created by HDI or NDI to create a tunnel arch 61. After creating the tunnel arch 61, the soil within the tunnel arch 61 can be removed ( Figure 14 ). Subsequently, the binder columns 39 can be reinforced with anchors 63. Finally, the tunnel arch 61 can be clad with a cladding 65, preferably made of shotcrete.

[0044] In this way, traffic tunnels, relief tunnels or underground channels up to 1 km long can be created.

[0045] A further application of the inventive drilling method is in the Figures 16 to 18 shown to carry out a ground stabilization beneath a building 66: After the borehole 11 and the binder column 39 have been produced as described above ( Figure 16 ), a strand 67 can be pulled into the borehole with the drill rod 15. The strand 67 can be a steel cable with head plates at the ends. The strand 67 is tensioned and anchored at its ends outside the borehole 11. Then, the remaining cavity in the borehole 11 is filled with a filling material 54. The strand 67 can stabilize the subsoil and stop settlement.

[0046] The present horizontal drilling method enables the creation of stable boreholes 11 without digging trenches, even when the soil is unstable and therefore the horizontal directional drilling method cannot be applied. Soil consolidation is achieved by a binder column 39, which is created by injecting a binder into the soil using a jet grouting method. Legend:

[0047] 11Borehole 13Drill head 15Drill rod 17Drill rod 19External thread 21Internal thread 23Drilling rig 25Starting pit 27Target pit 29Recycling system 31Jet jet element 33Nozzle 35First end of the drill rod 37Second end of the drill rod 39Binder column 41Valve 42Flap 43Coupling element 45Mixing system 47Silo 49Inlet line 50Coupling ends 51Excavation blade 52Reamer 53Product pipe 54Filling material 55Cavity 57Pump 59Soil surroundings of the borehole 60Tunnel 61Tunnel bend 63Anchors 65Casting 66Building 67Strand

Claims

1. Horizontal drilling process comprising the following working steps: 1) Producing of a pilot drilling for which a drilling head (13) on a drill string (15) with a multitude of drill rods (17) coupled the one behind the other is driven into the ground from a starter pit (25) to a target pit (27) and bentonite is transported via the drill string (15) to the drilling head (13) so that a drill hole (11) is formed, 3) Replacement of the drilling head (13) by a reamer (52) in the target pit (27) and widening of the drill hole (11) by pulling the reamer (52) from the target pit (27) to the starter pit (25) and 4) Optional repeat of step 3) with further reamers for the stepwise widening of the drill hole (11) further characterized by 2) integration of several jet grouting elements (31) coupled with one another into the drill string (15) with which a binder agent, in particular a cement grout, additionally introduced to the bentonite in the drill string (15) is injected into the ground surrounding the drill hole (11) with a jet grouting process before step 3) or during step 1) so that a hardened binder agent column (39) is formed.

2. Drilling process according to claim 1, characterized in that the jet grouting process is a high pressure injection or a low pressure injection.

3. Drilling process according to one of the claims 1 or 2, characterized in that a multitude of jet grouting elements (31) is integrated the one after the other into the drill string (17) and the opening and closing of the nozzles of a jet grouting element is controlled via the first end (35) of the drill string (15) that is free from the binder agent supply line.

4. Drilling process according to one of the preceding claims, characterized in that a coupling element (43) is provided between the second end (37) of the drill string (15) at which the binder agent is introduced and the binder agent supply line (49) from a mixing system (45), coupling element (43) in which the drill string (15) can rotate.

5. Drilling process according to one of the preceding claims, characterized in that the drill string (15) is moved back and forth and rotated during the hardening time of the binder agent over a distance of maximally 7 m.

6. Drilling process according to claim 5, characterized in that removal wings (51) are provided at the coupling ends (50) of the drill rods (17) that remove binder agent on the entire length of the drill hole (11) during the hardening time.

7. Drilling process according to one of the preceding claims, characterized in that the drill hole (11) is widened with a reamer (52) after step 1) and is rinsed with bentonite.

8. Drilling process according to one of the preceding claims, characterized in that the drill hole (11) is controlled and cleaned after step 3) or 4).

9. Drilling process according to the preceding claims, characterized in that a product pipe (53) is driven into the drill hole (11) by means of the drill string (15) after step 3) or 4).

10. Drilling process according to claim 9, characterized in that the control and cleaning of the drill hole (11) is performed a product pipe (53) of a maximal length of 5 m is drawn through the bore hole (11).

11. Drilling process according to one of the claims 9 or 10, characterized in that a hollow space (55) existing between the binder agent column and the product pipe (53) is filled with a filling material (54).

12. Drilling process according to one of the claims 1 to 8, characterized in that for constructing a tunnel - a multitude of drill holes (11) is drilled along a tunnel arch (61), the binder agent columns (39) of which contact each other, - the ground is removed inside the tunnel arch (61), - the tunnel arch (61) is reinforced with anchors (63) that penetrate the binder agent columns (39) and - the tunnel arch (61) is coated with sprayed concrete.

13. Drilling process according to one of the claims 1 to 8, characterized in that for soil stabilization below a set object, in particular a building (66), - a drill hole (11) and a binder agent column (31) are produced, - a strand (67) is driven into the drill hole (11), - the strand (67) is tensioned and anchored at its both ends and - the hollow space (55) that remains in the drill hole (11) is filled with a filling material (54).

14. Horizontal drilling system for carrying out a horizontal drilling process according one of the preceding claims comprising a multitude of drill rods (17) that are connected to a drill string (15) with a first and a second end (35, 37) and are driven by a drill rig (23) and a jet grouting element (31) with at least one nozzle (33) on its sheath is arranged between two adjacent drill rods (17) characterized in that several jet grouting elements (31) connected with one another are arranged the one behind the other between two adjacent drill rods and a valve (41) is arranged on each jet grouting element (31) that opens and closes the nozzles (31) of a jet grouting element (31), wherein the valve (41) is controlled by one of the drill rods (17) via the first end (35) of the drill string (15) and that the jet grouting elements (31) are supplied with binder agent via the second end (37) of the drill string (15).

15. Horizontal drilling system according to claim 14, characterized in that the system comprises a coupling element (43) for the binder agent supply from a mixing system (45), coupling element through which the binder agent is introduced into the second end (37) of the drill string (15) and coupling element (43) in which the drill string (15) can sealingly rotate.

16. Horizontal drilling system according to claim 14 or 15, characterized in that removal wings (51) are configured at the coupling ends (50) of the drill rods (17) the circumferential circle of which has a bigger diameter than the respective coupling end (50).