EP0634528B1 - Method for placing a binder suspension - Google Patents

Abstract

Method of producing consolidated or sealed bodies in the soil, in particular in the form of columns or laminations, in which a drill and injecting rod is sunk and is withdrawn again while placing binder suspension, the rod being sunk by the auger drilling method, and excess material being drawn off via the interior of the drill and injecting rod during the withdrawal of the rod and during the placing of the binder suspension. <IMAGE>

Description

The invention relates to a method for producing solidified or sealing bodies in the ground, in particular in the form of columns or lamellae, in which a drill and injection rod is sunk and pulled again with the application of binder suspension. The invention further relates to a drilling and injection rod for performing the method according to the invention.

Methods of the type described above are carried out with a low injection pressure of approximately 10 bar as a simple injection method and with a high pressure of 200 to 600 bar as a high-pressure injection method; the latter are known by the applicant under the Soilcrete brand name (VDI-Lexikon Bauingenieurwesen, Düsseldorf 1991, p. 270). It is customary here that a smooth, double-walled pipe rod, which is provided with a drill bit, also serves as a drill and injection rod. After the drill pipe has sunk, binder suspension is applied during the drawing process via nozzles in the vicinity of the drill bit, which are supplied via feed channels between the walls of the drill pipe. It is known here to apply the binder suspension in a high-pressure cutting jet or instead to apply the binder at a relatively low pressure and also to use water in a high-pressure cutting jet. In order to improve the effect, the high-pressure cutting jet can be coated with compressed air, a further supply duct for compressed air being formed in the interior of the double walls of the rod assembly.

If the injection rod is not pulled in a rotating manner, lamellar solidified bodies are formed from a mixture of binder suspension and soil material in accordance with the alignment of the nozzles; the injection rod is pulled in a rotating manner, the rotational speed being the pulling speed is to be coordinated, columnar solidified soil bodies are formed from binder suspension mixed with soil material.

In the case of heavy soils, the relatively slim, multi-walled linkage of a known type cannot be used for drilling the hole. When using the drilling and injection rod, there may be drilling deviations or damage to the rod. Neither is acceptable. In these cases, it was previously necessary to first drill the hole with a heavier drill pipe, pull it again and then bring down the special double-walled injection pipe, when pulling the binder suspension as a low-pressure injection alone or in addition to a high-pressure cutting jet or even as a high-pressure cutting jet has been.

The need to sink and pull two different poles is extremely disadvantageous and undesirable; it must be taken into account here that when the bores are deeper, rods from several longitudinal sections are used, the assembly and disassembly of which is particularly time-consuming if the rods are double or multi-walled.

From DE 37 18 480 C1, a drilling device for a high-pressure injection method is known, in which a wall-mounted linkage for a high-pressure suspension jet is arranged so as to be longitudinally displaceable in a further double-walled linkage for supplying flushing medium. Both rods have their own drill bits. This design requires particularly complicated drive means. The proposed procedure is extremely complex, with excess suspension flowing back to the surface in the annular space between the two rods. The risk of this annulus becoming blocked is addressed and should not be neglected.

US-A-3875751 describes a method for producing solidified bodies in the form of columns, in which a drill and injection rod is brought down by the screw drilling method and is pulled again with the application of binding agents. If it is intended to apply the binder in the form of a suspension, a central feed channel is provided in the double-walled drill pipe. Insofar as it is intended to apply the binder in powder form, with compressed air serving as the carrier material, a central feed channel is provided, which can be branched to the environment at the outlet. Above the outlet opening, this feed channel has openings through which the relaxed air inside the drill pipe can exit into an annular channel which surrounds the feed channel and into which it then flows back.

From GB-A-2062072 a drilling and injection rod with a central tubular body, which forms a central interior and an annular space surrounding it, is known, with a helical worm gear being attached to the outside of the tubular body. The interior and annulus are optionally provided for the simultaneous supply of binder suspension and setting accelerator or for the simultaneous supply of water and compressed air, the first combination being applied when pulling the drill pipe to produce a column body, while the second combination when bringing down the drill pipe for the purpose of lightening drilling is carried out.

Proceeding from this, the present invention is based on the object of providing a method and a device for carrying out the method of the type mentioned at the outset which, even in the presence of heavy soils, permits the drilling and injection method described above to be carried out in one operation.

The solution consists in a method which is characterized in that the drilling and injecting rod is brought down in the worm drilling method and in that the excess material which rises in the borehole when the rod is pulled and when the binder suspension is applied is discharged via the interior of the rod.

The auger drilling method allows drilling in dense soils in a manner known per se. The excess material rising in the borehole when the suspension is brought out, which is considerably impeded by a screw, can flow out through the interior of the rod according to the invention, so that despite the use of the screw drilling method, the injection according to a normal injection method with a pressure of about 10 bar or the injection after the high-pressure injection process with pressures of 200 to 600 bar can be carried out without problems, without the screw of the rod interfering with the return material. This rises through the interior of the rod instead of having to find the way in the borehole outside the rod, as in known injection methods.

The method is particularly advantageously carried out in such a way that compressed air is fed to the interior of the rod, so that the dough speed of the material in the interior is increased significantly. This loosens up the return material and prevents clogging of the inside of the boom, even if the soil is firm. It is particularly advantageous if compressed air is supplied to the interior of the boom at different heights.

As is known as such, a high-pressure injection method can be modified such that the cutting jet used is encased in compressed air by arranging ring nozzles for compressed air concentrically with the cutting jet nozzles. In this case, the cutting jet can be formed by binder suspension fed under high pressure or by water fed under high pressure, in the latter case the binder suspension being fed again under lower pressure.

According to the different tasks, it is possible to adjust the compressed air to a different pressure level to the inside of the tube body than the compressed air to the ring nozzles that surround the cutting jets.

Depending on the consistency of the soil, the rod can be pulled non-rotating, whereby part of the task of the cutting jet is anticipated by enlarging the borehole; In the case of particularly solid floors, the boom can be pulled in a direction opposite to the direction of rotation when sinking to protect the material against excessive loads.

According to the invention, a drilling and injection rod suitable for carrying out the above-mentioned method comprises a double-walled tubular body which forms a central interior and an annular space which is provided for guiding binder suspension and has at least one nozzle outlet at the lower end of the rod and to the surroundings, at least one helical worm gear is attached on the outside, the tubular body having at least one jacket opening for removing the excess material rising in the borehole when the binder suspension is being discharged at the lower end of the rod, which has a passage channel through the walls of the tubular body, which is sealed against the annular space, connects the central interior with the surroundings. The jacket opening can be designed in such a way that the return of material from the environment into the interior and the outflow is promoted. The jacket opening can be adapted to a specific direction of rotation of the linkage when pulling.

In this case, the at least one jacket opening can preferably be covered with a closure flap which can be opened or removed by pressurizing the interior of the tubular body. This effectively prevents the interior of the tubular body from becoming clogged with soil material which is not loosened or suspended by binder suspension when the rod is being sunk.

Further advantageous embodiments of the linkage according to the invention are described in the subclaims, the type of division of the annular space for the supply of binder suspension, water and air and the arrangement of annular nozzles for compressed air, which are the nozzles for the high-pressure cutting jets surrounded in a ring, can be done in a known design. Reference is hereby made to the content of the subclaims.

A particularly preferred new embodiment is that at least one outlet nozzle for air to the interior of the tubular body is arranged in the linkage, preferably even several outlet nozzles to the interior are arranged at different heights in order to use the method previously described for loosening the return material in the interior to be able to. This outlet nozzle is preferably arranged above the jacket opening.

If the supply of compressed air to ring nozzles, which surround the cutting jets, and of compressed air to the interior of the tubular body for loosening the return material are provided at the same time, either two different compressed air supply lines can be provided in the annular space in order to generate a different pressure level, or - preferably in association with the nozzles - means for reducing the pressure can be provided in front of at least one type of nozzle.

In a preferred embodiment it is provided that the outlet nozzles for suspension are arranged below the at least one jacket opening. As a result, the return flow of suspension through the jacket opening when pulling the rod is kept low.

In a further favorable embodiment it is provided that at least one outlet nozzle for a cutting jet - in particular from water - is arranged above the at least one jacket opening. As a result, the return material is opened up in a favorable manner for the outflow via the jacket opening when the rod is pulled.

Figur 1

zeigt einen Längsschnitt durch ein erfindungsgemäßes Gestänge mit einer Ansicht des Schneckenganges in einer ersten Ausführung;

Figur 2

zeigt einen Längsschnitt durch ein erfindungsgemäßes Gestänge nach Figur 1;

Figur 3

zeigt einen Querschnitt durch ein erfindungsgemäßes Gestänge mit einer Ansicht des Schneckenganges in einer zweiten Ausführung;

Figur 4

zeigt einen Querschnitt durch ein erfindungsgemäßes Gestänge nach Figur 3.

Preferred embodiments of the lower end of a drill and injection rod according to the invention are shown in the figures.

Figure 1

shows a longitudinal section through an inventive linkage with a view of the screw flight in a first embodiment;

Figure 2

shows a longitudinal section through an inventive linkage according to Figure 1;

Figure 3

shows a cross section through an inventive linkage with a view of the worm gear in a second embodiment;

Figure 4

shows a cross section through an inventive linkage according to Figure 3.

The figures are described below, to the extent that they match, the same details being given the same numbers in the figures.

The lower end of a drilling and injection rod 1 can be seen, which comprises a double-walled tubular body 2, which forms an annular space 3 and a central interior 4. On the outside of the tubular body, a worm gear 5 shown in view is attached. Near the lower end, a jacket opening 6 is provided in the tubular body, which ends with a drill tip 7.

According to Figures 1 and 2, the annular space 3 is formed into a longitudinal channel 8 for suspension and a longitudinal channel 9 for compressed air. Two radial nozzles 10, 11 extend from the longitudinal channel 8 and deliver the suspension, in particular in the high-pressure jet. These nozzles are encased by ring nozzles 12, 13 for compressed air. In addition to the ring nozzles 12, 13, a further nozzle 14 goes from the longitudinal channel 9 for compressed air into the interior 4 for the return material.

The nozzles 10, 11 are located below the jacket opening 6 in the tubular body, the nozzle 14 above the jacket opening.

According to FIGS. 3 and 4, the annular space 3 is divided into a longitudinal channel 8 for suspension, a longitudinal channel 9 for compressed air and a longitudinal channel 15 for cutting water. A radial nozzle 16 extends from the longitudinal channel 8 and delivers the suspension. A nozzle 17 emerges from the longitudinal channel 15 and delivers cutting water under high pressure. This is through an annular nozzle 18 for Compressed air jacketed. In addition to the ring nozzle 18, a further nozzle 14 leads from the longitudinal channel 9 for compressed air into the interior 4 for the return material. The nozzle 16 for suspension is located below the jacket opening 6 in the tubular body, the nozzles 17 and 14 above.

The linkage according to the invention can be composed of individual longitudinal sections.

Claims (16)

1. A method of producing consolidated or sealing members in the soil, especially in the form of columns or diaphragms, wherein a drilling and injection rod (1) is lowered, and lifted while ejecting a binding agent suspension,
   characterised in
   that the drilling and injection rod (1) is lowered using the helical drilling method and that the excess material rising in the borehole while lifting the rod (1) and ejecting the binding agent suspension is discharged through the interior of the rod (1).
2. A method according to claim 1,
   characterised in
   that while the binding agent suspension is being ejected, compressed air is introduced into the interior of the rod (1).
3. A method according to claim 1 or 2,
   characterised in
   that the binding agent suspension is ejected in at least one substantially radial cutting jet from the drilling and injection rod (1), which cutting jet emerges from the drilling and injection rod,preferably surrounded by compressed air.
4. A method according to claim 1 or 2,
   characterised in
   that water is ejected in at least one substantially radial cutting jet from the drilling and injection rod (1), which cutting jet emerges from the drilling and injection rod, preferably surrounded by compressed air.
5. A method according to claims 2 and 3 or 2 and 4,
   characterised in
   that the pressure levels of the compressed air entering the interior of the rod (1) and of the compressed air emerging outwardly from the rod (1) differ.
6. A method according to any one of claims 1 to 5,
   characterised in
   that the rod (1) is lifted while rotating, especially in the direction opposed to the direction of rotation during drilling.
7. A method according to any one of claims 1 to 6,
   characterised in
   that the rod (1) is lifted in a non-rotating condition.
8. A drilling and injection rod (1) for carrying out a method according to any one of claims 1 to 7, having a double-wall tubular member (2) which comprises a central inner chamber (4) and an annular chamber (3), which is provided for the purpose of guiding a binding agent suspension, and which comprises at least one nozzle exit (10 - 13) arranged at the lower end of the rod (1) and leading to the environment, to which tubular member, on the outside, there is attached at least one spiral turn and which tubular memher is provided with at least one mantle aperture (6) for discharging the excess material rising in the borehole when ejecting the binding agent suspension, which mantle aperture (6) connects the central inner chamber (4) to the environment by means of a through-channel which extends through the two walls of the tubular member and which is sealed relative to the annular chamber (3).
9. A rod according to claim 8,
   characterised in
   that the annular chamber (3) is divided into at least two longitudinal channels (8, 9) for guiding binding agent suspension and compressed air and, optionally, a longitudinal channel (15) for guiding water and that said channels each comprise exit nozzles (10, 11, 16; 12, 13, 18, 17) provided for binding agent suspension (10, 11, 16), for compressed air (12, 13, 18) and for water (17) and leading outwardly to the environment.
10. A rod according to claim 9,
    characterised in
    that the exit nozzles (12, 13, 16) for compressed air concentrically and annularly surround the exit nozzles (10, 11, 16) for a cutting jet consisting of binding agent suspension (10, 11) or water (16).
11. A rod according to any one of claims 9 or 10,
    characterised in
    that at least one exit nozzle (14) for compressed air leading to the inner chamber (4) of the tubular member (2) is arranged in the rod (1), especially above the at least one mantle aperture (6).
12. A rod according to claim 11,
    characterised in
    that a plurality of exit nozzles for compressed air leading to the inner chamber (4) of the tubular member (2) are arranged in the rod (1) at different levels relative to one another.
13. A rod according to any one of claims 9 to 12,
    characterised in
    that the exit nozzles (10, 11, 16) for suspension are arranged below the at least one mantle aperture (6).
14. A rod according to any one of claims 9 to 13,
    characterised in
    that at least one exit nozzle (17) for a cutting jet, especially consisting of water, is arranged above the at least one mantle aperture (6).
15. A rod according to any one of claims 8 to 14,
    characterised in
    that the at least one mantle aperture (6) can be covered by a sealing cap which is opened or removed by pressurising the inner chamber (4) of the tubular member (2).
16. A rod according to any one of claims 11 to 15,
    characterised in
    that there are provided means for loading the nozzle exits (12, 13; 14) for compressed air leading to the inner chamber and to the environment with different pressure levels, especially longitudinal channels separated from one another or one individual longitudinal channel with different pressure reducing valves.

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