Percussion tube for hitting a hole in the ground

Abstract

The invention relates to a driving tube (1) comprising a striking surface (7) and a straight tube (2), wherein the straight tube (2) is intended to be driven axially into the ground with its open front end facing forward by striking the striking surface (7) in the axial direction of the straight tube (2), and the impact impulse is transmitted to the straight tube (2). In a longitudinal region of the driving tube (1), which is displaced relative to the striking surface (7) towards the front end of the driving tube (2), there is an outlet opening (5) for soil material, through which the interior of the straight tube (2) is open to the surroundings.

Description

[0001] The invention relates to a percussion tube for drilling a borehole in the ground, and to an associated method.

[0002] "Building ground" within the meaning of this document is solid material of the earth's surface in the outdoor area, i.e. typically soil, clay, gravel, etc.

[0003] German patent DE 2209193 A1 discloses a driving pipe which includes, among other things, a straight pipe that is driven axially into the ground to create a borehole. The front (lower) end of the driving pipe is open at the end face, and the rear end of the driving pipe serves as a striking surface against which a blow is struck axially to drive the driving pipe into the ground. Typically, this striking action is performed using a hydraulically driven hammer, which is mounted as an interchangeable tool on an excavator arm. As the driving pipe is driven into the ground, it fills with soil material. When the driving pipe is withdrawn from the borehole, the soil material within it is usually displaced along with it. This material then has to be removed from the driving pipe, which requires considerable effort.Even if the percussion tube is open towards the striking surface - i.e. towards the top side - no soil can be forced out of the percussion tube during the movement of the percussion tube into the ground, since the top surface is closed by the percussion device.

[0004] DE 2224747 A1 discloses a percussion tube which, compared to that of DE 2209193 A1 – to which it refers – is improved in that it can be fitted with an end cap at the rear. A compressed air line passes through this cap, allowing compressed air to be forced into the rear section of the percussion tube. This makes it possible, after the percussion tube has been withdrawn from a bore, to push or blow the core of subsurface material located inside the tube outwards to the front end of the percussion tube.

[0005] EP 0457791 B1 and DE 202009010960 U1 also show impact tubes that are driven into the subsoil, with subsoil material penetrating the volume enclosed by the impact tube. In these examples as well, the subsoil material cannot ooze out of the upper end opening of the impact tube during the driving motion, as this opening is sealed by the impact device.

[0006] CN 216157585 U describes a device for placing sensors underground. A pipe is pushed into the ground. The subsurface material located at the lower end of the pipe is agitated by compressed air and blown out through a lateral outlet channel on the upper surface of the pipe.

[0007] Starting from this state of the art, the problem underlying the invention is to improve a drive pipe comprising a straight pipe which is intended to be driven axially into the subsoil, in such a way that the removal of material from the subsoil from the interior of the straight pipe can be accomplished with less effort.

[0008] To solve the problem, it is assumed that a straight pipe is used which is open at the front end, and that the rear area is indirectly driven into the ground in the axial direction.

[0009] As a further development according to the invention, it is proposed to provide an outlet opening for subsurface material in a longitudinal area of ​​the percussion tube which is shifted towards the front end face of the percussion tube relative to the striking surface, through which the interior of the straight tube is open to the environment.

[0010] By positioning the outlet opening away from the striking surface – the surface against which a striking tool strikes to drive the driving tube into the ground – the striking tool does not temporarily close the outlet opening. This allows subsoil material pushed into the driving tube from the front (lower) end face during the driving process to be forced out through the outlet opening located higher up, without requiring any separate work step.

[0011] The invention, including further advantageous features, will be discussed in more detail with reference to somewhat stylized drawings of exemplary percussion tubes according to the invention.

[0012] Fig. 1 bis Fig. 4 Each figure shows a separate exemplary percussion tube according to the invention in a lateral sectional view.

[0013] The impact tube 1 of Fig. 1 The assembly largely comprises a straight pipe 2, a flared extension 3, and an outlet channel 4, which surrounds an outlet opening 5. All these parts are typically made of solid steel. Typically, but not necessarily, the outlet channel 4 and the flared extension are welded together to form a monolithic part, and this part is connected to the straight pipe 2 by a flange connection.

[0014] For intended use, the striking surface 7 of the striking extension 3 is struck in the direction indicated by an arrow 6 in order to strike the striking tube 1 with its in Fig. 1 to drive the lower front face into the ground.

[0015] During this driving process, material from the subsoil penetrates from below through the open end face of the straight pipe 2 into the volume enclosed by this pipe 2. With each blow, the material in the straight pipe 2 is forced further upwards. The aforementioned volume is open to the surroundings in its upper region through the outlet opening 5. Unlike the prior art designs discussed, this outlet opening 5 is not temporarily closed by the striking tool, which, as intended, repeatedly strikes the striking surface 7 from above. The portion of the subsoil material furthest upwards, thus being forced into the driving pipe 1, escapes unhindered through the outlet opening 5 from the driving pipe 1 into the surroundings, even as the driving pipe 1 is being driven into the subsoil.

[0016] As intended, after drilling a borehole, the percussion pipe 1 is lifted, thereby pulling the straight pipe 2 out of the borehole. The soil material still present in the straight pipe 2 and in the outlet channel 4 is also lifted up in the process. It is not necessary to remove it from pipe 2 in a separate operation, as it will be forced out of the outlet channel 4 anyway when the next borehole is drilled due to the advancing material.

[0017] In the construction method according to Fig. 1 The outlet opening 5 is the end of an outlet channel 4, which extends below the impact surface 7 from the straight pipe 2 to a region significantly spaced from the axis of the straight pipe 2. Preferably, the outlet channel 4 is inclined at an acute angle to the axis of the straight pipe 2. More preferably, the acute angle increases continuously with the distance along the flow path of the outlet channel 4. Preferably, the cross-sectional area of ​​the outlet channel 4 also increases with the distance along the flow path of the outlet channel 4. These measures facilitate the particularly easy flow of material from the subsoil into and through the outlet channel 4.

[0018] Fig. 2 Figure 1 shows a percussion tube 1 according to the invention, in which the outlet opening 5 is divided into several partial surfaces which are arranged between the straight tube 2 and the striking surface 7 approximately flush with the outer surface of the straight tube 2. For this purpose, the striking extension 3 is designed as an upper plate 8 with an upper striking surface 7 and with downwardly projecting column-like supports 9, which are supported downwardly against the upper end face of the straight tube 2. The straight tube 2 is open at its end face upwards towards the volume surrounded by the supports 9.

[0019] Material from the subsoil, which is forced through the straight pipe 2, falls after exiting the straight pipe 2 through the opening 5, the surface of which is divided by the supports 9, in all directions around the straight pipe 2.

[0020] To facilitate the flow of subsoil material through the opening 5, the area of ​​the opening 5, i.e., the sum of the open areas between the supports 9, should be significantly larger – for example, twice as large – as the cross-sectional area of ​​the interior of the straight pipe 2.

[0021] According to a preferred embodiment of the striking tube 1, the cross-sectional area of ​​the front end-face opening of the straight tube 2 is narrowed compared to the cross-sectional area of ​​the interior of the straight tube 2 behind it. Preferably, this narrowing is formed by a projection 10 extending radially inward from the outer surface of the straight tube 2 at its front end face, relative to the axis of the straight tube 2. This projection 10 typically has the form of a ring, as shown, with its outer surface adjoining and being connected to the inner surface of the striking tube. It can, for example, be produced as a coating applied to the striking tube 2 by welding. Alternatively, it could be formed as a separate ring welded to the end face of the striking tube 2.

[0022] The cross-section of the flow of soil material entering the straight pipe 2 during its driving into the ground is narrower due to the aforementioned projection 10 than in the subsequent longitudinal section of the straight pipe 2. This results in the flow being subjected to significantly lower pressure against the inner surface of the straight pipe 2 in the majority of its longitudinal section than it would otherwise be. Consequently, the soil material inside the straight pipe 2 is compacted much less than it would be in a construction method without the projection 10. This greatly facilitates the transport of the material through the straight pipe 2. A further advantage of the projection 10 is that when the driving pipe 1 is lifted away from the ground, the soil material inside the straight pipe 2 cannot remain as a column in the subsoil.The risk of such a column remaining standing is otherwise primarily present when the subsoil is very loamy.

[0023] Fig 3 illustrates two further preferred developments of a percussion tube according to the invention.

[0024] One further development concerns the opening leading into the straight pipe 2 from below. Preferably, this opening has an inlet ramp, and further preferably, the radial thickness of the annular end face surrounding this opening at its bottom is less than the wall thickness of the straight pipe. Compared to a blunt design without an inlet ramp, this facilitates driving the pipe into the ground.

[0025] The second development concerns the connection of the striking tube 1 to a machine that performs the required blows on the striking surface 7. Typically, this machine is a swiveling arm of a mobile machine, such as an excavator, equipped with a hydraulically driven hammer.

[0026] For connection to this arm, the striking tube 1 is as follows: Fig. 3 provided with at least one eyelet 11 to which a flexible pulling element 12, i.e. a chain or a rope or a strap, is attached, which is also connected to the swiveling arm, so that an angle-flexible tensile-resistant connection is formed between the percussion tube 1 and the swiveling arm, with the help of which the percussion tube 1 can be easily pulled out of a borehole driven into the ground and transported to the next drilling location.

[0027] For the striking itself, the construction method according to Fig. 3 This applies when the swiveling arm of the mobile work machine is equipped with a hydraulically driven chisel, a type commonly used for removing rock or concrete. The impact tube 1 is fitted with a guide sleeve 13, which extends upwards from the impact surface 7 on the striking extension 3 as an open tube. During impact, the chisel projects through the guide sleeve 13 onto the impact surface 7 and strikes it in the same way as it would rock, which the chisel is intended to break apart. The guide sleeve 13 preferably has a significantly larger inner diameter than the chisel's outer diameter, resulting in a very loose fit between the chisel and the guide sleeve, thus allowing the impact tube some angular movement relative to the chisel.For example, the inner diameter of the guide sleeve can be 96 mm, the diameter of the chisel 80 mm, and the length of the guide sleeve can be 250 mm.

[0028] Fig 4 In addition to features already discussed above, it also illustrates that when driving the driving tube 1 into the ground as intended, it is also possible to drive in an additional part, a so-called "lost tube" 14, which can remain in the ground, for example as lost formwork for subsequent pouring with a hardenable compound, or simply as an outer part of a plug connection into which any kind of stakes, such as fence posts or traffic sign posts, can be inserted.

[0029] Before being driven into the ground, the lost pipe 14 is slid onto the straight pipe 2 as a casing. Preferably, the lost pipe 14 is provided with a radially inwardly projecting projection 15 on its end face, which is located in the region of the front end face of the straight pipe 2 belonging to the driving pipe 1. This projection rests against the front end face of the straight pipe 2. Typically, this projection 15 is a ring whose inner diameter is smaller than the outer diameter of the straight pipe 2 and which is welded to the end face of the lost pipe 2. During the driving process, the projection 15 is struck against the subsoil material, and subsoil material slides off this projection 15.The projection 15 ensures that the predominant longitudinal section of the lost pipe 14 is subjected to only slight tensile stress during insertion, rather than strong compressive stress, and that no subsurface material enters the annular gap between the lost pipe 14 and the straight pipe 2. Subsurface material in this annular gap would be highly disruptive, as it would cause friction and thus lead to the lost pipe 14 being pulled out along with the straight pipe 2 when it is withdrawn.

Claims

1. A striking tube (1) comprising a striking surface (7) and a straight tube (2), wherein the straight tube (2) is intended to be driven axially into the ground with its open front end facing forward by striking the striking surface (7) in the axial direction of the straight tube (2), and the impact impulse is transferred to the straight tube (2), characterized by the fact that in a longitudinal area of ​​the percussion tube (1), which is shifted relative to the percussion surface (7) towards the front end face of the percussion tube (2), there is an outlet opening (5) for material from the subsoil, through which the interior of the straight tube (2) is open to the surroundings.

2. Impact tube (1) according to claim 1, characterized by the fact thatthe striking surface (7) is located on an impact extension (3) belonging to the striking tube (1), which is connected to the straight tube (2) at its rear open end face, and the outlet opening (5) is also located in the longitudinal area of ​​the impact extension (3) with respect to the axial direction of the straight tube (2).

3. Impact tube (1) according to claim 1 or 2, characterized by the fact that the outlet opening (5) is located at the end of an outlet channel (4) which leads from the straight pipe (2) to an area clearly spaced from the axis of the straight pipe (2) and is inclined at an acute angle to the axis of the straight pipe (2).

4. Impact tube (1) according to claim 1 or 2, characterized by the fact that the outlet opening 5 is located on the impact extension (3) and is arranged approximately in line with the outer surface of the straight tube (2).

5. Impact tube (1) according to claim 4, characterized by the fact thatthe impact extension (3) comprises a plate (8) lying normal to the axial direction of the straight tube (2), the surface of which facing away from the straight tube (2) is the impact surface (7), the plate (8) being supported by column-like supports (9) towards the rear end face of the straight tube (2), and the outlet opening (5) extending in several partial surfaces between the supports (9).

6. Impact tube (1) according to one of claims 1 to 5, characterized by the fact that the cross-sectional area of ​​the front end opening of the straight tube (2) is narrower than the cross-sectional area of ​​the interior of the straight tube (2) behind it.

7. Impact tube (1) according to one of claims 1 to 6, characterized by the fact that the front opening of the straight tube (2) has an inlet slope.

8. Impact tube (1) according to one of claims 1 to 7, characterized by the fact that the striking surface (7) is located at the bottom of a guide sleeve (13).

9. Impact tube according to one of claims 1 to 8, characterized by the fact that it has an eyelet (11) to which a flexible traction element (12) is attached which is suitable as a connecting element to a device supporting the striking tube (2).

10. Method for drilling a bore using a percussion tube (1) according to any one of claims 1 to 9, characterized by the fact that Even during the driving of the straight pipe (2) of the driving pipe (1), material of the subsoil which was previously pushed into the straight pipe (2) is forced out through the outlet opening (5) of the driving pipe (2).

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