Mixing device and method for producing a columnar or lamellar ground mixing element in the ground, and use of granular bulk material for producing such a ground mixing element

Abstract

The invention relates to a mixing device (40) for producing a columnar or lamellar ground mixing element (60) in the ground, having a tubular mixing rod (41) with at least one inner supply line, a tool (42) which is arranged at a lower end of the mixing rod (41) and which is designed to loosen and mix ground material and has at least one outlet opening (47) which is connected to the at least one inner supply line, and a rotary drive (43) for rotationally driving the mixing rod (41) with the tool (42) attached thereto for producing a mixing region in the ground. A receiving device (44) for receiving a granular bulk material is formed on an upper region of the mixing rod (41), and a first inner supply line is designed to conduct the received granular bulk material from the receiving device (44) through the mixing rod (41) to at least one first outlet opening (47) in order to form the columnar or lamellar ground mixing element (60) in the ground. Material with a grain size of up to 100 mm, preferably from 2 mm to 70 mm, in particular comminuted rubble, in particular in a mixture with loosened ground material and a binder, in particular a cement suspension, is used as granular bulk material.

Description

[0001] II? whimsical & home i ■ PATENT ATTORNEYS

[0002] B 3894

[0003] MIXING DEVICE AND METHOD FOR CREATING A COLUMN OR LAMELLA-SHAPED SOIL MIXING ELEMENT IN THE SOIL AND THE USE OF GRANULES FOR THE PRODUCE OF SUCH A SOIL MIXING ELEMENT

[0004] The invention relates to a mixing device and a method for creating a columnar or lamellar soil mixing element in the soil, as well as the use of granular bulk material for the production of such a soil mixing element.

[0005] Methods and devices for in-situ mixing of soil and suspension are used particularly in specialist foundation engineering for the construction of foundation elements in the ground. In these methods, when a drilling tool, such as an auger, is inserted, the soil is liquefied by adding cement suspension and optionally bentonite suspension (two-phase) and mixing the loosened soil material. A generic mixing device and a method based thereon for creating a borehole in the ground and constructing a column-like element by in-situ mixing of loosened soil material and a cement suspension are known, for example, from EP 4 101 987 A1.

[0006] The drilling tool known from EP 4 101 987 A1 has a tubular drill shaft, at least one removal device designed for removing soil material, a feed device for supplying a fluid through the drill shaft via at least one outlet opening for the fluid into the borehole, and at least one mixing element extending radially to the drill shaft, which is arranged on the drill shaft axially spaced from the removal device and is designed for mixing soil material with the fluid. The soil material crushed by the removal device on the auger is conveyed upwards into an upper region of the borehole. During drilling, a curable suspension can be introduced via an outlet opening on the drill shaft, whereby the mixing elements mix the suspension with the crushed soil material to produce a so-called soil mortar in situ.Once a final depth is reached, the drilling tool is withdrawn from the borehole, whereby, if necessary, further drilling suspension is added and the drilling tool is rotated for further mixing, resulting in a finished soil mortar which can then harden to form the foundation element.

[0007] In the drilling tool known from EP 4 101 987 A1, at least one first outlet opening is arranged in the area of ​​the removal device and at least one second outlet opening is arranged axially spaced from the at least one first outlet opening, wherein fluid can be selectively introduced into the bore via an actuating device either via the at least one first outlet opening and / or the at least one second outlet opening in order to introduce the fluid into the bore at specific times via specific outlet openings.

[0008] In these processes, the mixture is bound by a cement matrix, and a column-shaped soil mixing element erected in the ground consists of soil material and cement. Optionally, steel beams can be embedded in the mixture while it is still soft. A disadvantage of these solutions is that the strength of the erected column-like element (without steel reinforcement) is in the lower MPa range.

[0009] An increasingly important aspect in civil engineering, as in other areas of the construction industry, is the high consumption of resources and materials for the production of cement and building materials such as sand, gravel and the like, as well as the costly disposal of construction waste, for example in landfills.

[0010] The invention is based on the objective of providing a mixing device and a method for creating a columnar or lamellar soil mixing element in the ground, with which a stable soil mixing element can be produced with lower resource consumption and a reduced CO2 footprint. A further aspect of the invention is to provide for the environmentally sound treatment of construction waste.

[0011] The problem is solved, firstly, by a mixing device for creating a columnar or lamellar soil mixing element in the ground with the features of claim 1, and secondly, by a method for creating a columnar or lamellar soil mixing element in the ground with the features of claim 11. The invention further proposes, to solve the problem, the use of granular bulk material, in particular crushed construction waste, for producing such a soil mixing element according to claim 15. Preferred embodiments of the invention are specified in the dependent claims.

[0012] The mixing device according to the invention for creating a column- or lamellar-shaped soil mixing element in the soil comprises, firstly, a tubular mixing rod with at least one inner feed line, a tool arranged at a lower end of the mixing rod which is designed for loosening and mixing soil material and has at least one outlet opening which is connected to the at least one inner feed line, and a rotary drive for rotating the mixing rod with the tool attached to it for creating a mixing area in the soil.

[0013] Furthermore, the mixing device according to the invention is characterized in that a receiving device for receiving a granular bulk material is formed on an upper area of ​​the mixing rod, and that a first inner feed line is formed to guide the received granular bulk material from the receiving device through the mixing rod to at least a first outlet opening for forming the column- or lamellar soil mixing element in the soil.

[0014] The inventive method for creating a column- or lamellar soil mixing element in the ground is carried out by means of a mixing device, in particular the inventive mixing device, which comprises a tubular mixing rod with at least one internal feed line, a tool arranged at a lower end of the mixing rod through which soil material is loosened and mixed to form a borehole in the ground, wherein the tool has at least one outlet opening which is connected to the at least one internal feed line, and a rotary drive by which the mixing rod with the tool attached thereto is driven in a rotating manner to create a mixing area in the ground. The inventive method is further characterized in that a receiving device is formed on an upper region of the mixing rod into which a granular bulk material is fed or...is supplied, and that a first internal feed line is formed through which the granular bulk material is conveyed from the receiving device through the mixing rod to at least a first outlet opening to form the columnar or lamellar soil mixing element in the soil.

[0015] A fundamental aspect of the invention is that, by means of the specially designed mixing device, a granular bulk material, in particular a solid, i.e., hard material with a grain size of up to 100 mm, preferably from 2 mm to 70 mm, especially gravel or crushed construction debris, is fed into the receiving device at the upper end of the tubular mixing rod and from there, under the influence of gravity, is guided through the inner feed line formed or arranged in an inner volume of the tubular mixing rod to the outlet opening on the tool, which is also adapted to the bulk material, and from there emerges to the outside. The tool is designed to loosen and mix the soil material, for example, at the depth of a borehole formed in the ground by the tool itself during drilling or previously by another tool.

[0016] The introduction of the granular aggregate through the discharge opening into the mixing zone, and the continuous or intermittent mixing of the loosened soil material and the added granular aggregate, leads to a homogenization of the components into a matrix in which all grain fractions are mixed and bonded together for improved force transmission. Optionally, a binder suspension or dry binder can also be added to the mixing zone, for example, also through the interior of the mixing rod, more precisely through one or more feed lines located or integrated there. After the mixing rod and the attached tool are removed, this mixing zone hardens into a stable "gravel column," i.e., the columnar or lamellar soil mixing element, which is formed by this process.The device can also be used in non-displaceable soils. The granular, coarse aggregate, fed directly into the mixing area via the internal feed line and the outlet opening, replaces fresh gravel and reduces the need for cement. In particular, when crushed construction debris is used as coarse aggregate, it can be reused as a high-quality building material with minimal processing effort, both materially and functionally, and disposed of economically and ecologically. These effects collectively reduce resource consumption, leading to lower energy consumption and consequently reduced CO2 emissions.Furthermore, by mixing the granular, coarse bulk material as an aggregate into the formed matrix, an increase in strength and / or a reduction in the cement content (with the same strength) of the columnar lamellar soil mixture element in the soil can be achieved.

[0017] In the process according to the invention, the soil mixing process known per se and described above is used as a basis or initial process, in which soil liquefaction is achieved by loosening and mixing the soil material when a drilling or mixing tool is inserted, optionally with the addition of a binder that increases the bonding in the matrix, in particular a cement suspension. This process is extended by mixing the loosened soil material and the additionally added granular bulk material in the mixing zone to form a soil mortar, which hardens to form the soil mixing element in the soil. The known process sequence thus remains the same except for the addition of the granular bulk material as aggregate (e.g., gravel or crushed construction waste), preferably during the withdrawal phase of the drilling or mixing tool.This allows the installation of the mixed "gravel column", i.e. the column- or lamellar-shaped soil mixture element consisting of soil material Z aggregate (Z cement) over the entire depth in the ground, to be achieved through a defined process.

[0018] Furthermore, additional reactive additives for contamination binding / reduction can be added during the process via the interior of the tubular mixing rod.

[0019] Preferably, the mixing device comprises a carrier device with a mast along which the rotary drive is slidably mounted by means of a drive carriage, wherein a feeding device for feeding granular bulk material to the receiving device may also be slidably mounted along the mast.

[0020] The movable mounting of the rotary drive and, if applicable, the feed unit along the mast enables continuous rotation of the mixing rod and the tool, as well as gravity-induced feeding of the granular, coarse bulk material into the receiving unit and from there through the interior of the drill string as the tool is withdrawn from the ground to the entire installation depth. The feed unit ensures that the feeding of the bulk material into the receiving unit does not stall or that the process does not need to be interrupted by stopping the rotation and refilling the receiving unit with more bulk material.

[0021] Preferably, the mixing rod has at least a second feed line for supplying a liquid or suspension to the tool and / or at least a third feed line for supplying a gas, in particular air, for conveying the bulk material in the first inner feed line and / or in the tool. The additional feed lines can also be routed through the interior of the mixing rod and are adapted in terms of dimensions and throughput capacity to the fluid being supplied (suspension, water, air, etc.).It is also conceivable that the second or a third supply line and the third or a third supply line are identical and can be used selectively for the fluid to be supplied, if this is possible due to the dimensioning and arrangement and the positioning and design of the respective associated of several outlet openings on the tool, which communicate with the at least one first inner supply line and / or the at least one second supply line, if present, and / or the at least one third supply line, if present.

[0022] To ensure a continuous supply of bulk material throughout the entire or at least the relevant part of the process when retracting the drill string above the desired height, the material receiving device can include a storage unit, in particular a bulk material hopper, with an increased volume. Naturally, a funnel-shaped inlet can be provided at the storage unit to facilitate the introduction of the bulk material. Preferably, a vibrating drive for conveying the bulk material is arranged in the first inner feed line and / or in the tool to support the otherwise gravity-driven transport of the bulk material, in addition to the rotary motion of the drill string, and to prevent blockage of the inner feed line.Such a blockage can easily occur, especially with coarser bulk material, as larger pieces can wedge themselves against each other and then obstruct the inner diameter of the feed line. Such a vibratory drive can be positioned at several points along its length.

[0023] Preferably, the tool comprises dissolving elements, in particular teeth, for loosening soil material and mixing elements (e.g., mixing paddles known per se) for mixing the loosened soil material with the supplied bulk material and / or liquid and / or gas. The dissolving elements and the mixing elements can be rotatably mounted on the tool relative to each other. The shape, the relative arrangement including circumferential and axial spacing, and the number of dissolving and mixing elements can be selected depending on the bulk material to be introduced, with one aspect for the design being the most uniform possible distribution of the bulk material or aggregate across the column cross-section.

[0024] A preferred arrangement of mixing elements is the formation of mixing paddles at the lower end of the tool, which are designed to mix the bulk material supplied above the mixing paddles into the loosened soil material in the mixing area when the tool is pulled.

[0025] With regard to the process, it can be advantageous if the loosened soil material is at least partially removed from the mixing zone, while granular bulk material is fed into the mixing zone. This allows the composition of the mixing zone to be controlled for a desired matrix formation, and the proportions of soil material and bulk material can be varied. The removal of loosened soil material can be carried out in a manner known per se through the interior of the mixing rod.

[0026] Particularly advantageous with regard to the strength of the soil mixing element erected in the ground, consisting of loosened soil material and bulk material as aggregate and, if necessary, a curable binder suspension after pulling the mixing rod with tool, is the use of a granular bulk material fed into the receiving device as material with a grain size of up to 100 mm, preferably from 2 mm to 70 mm, in particular as gravel and / or crushed construction waste in the aforementioned size ranges.

[0027] The soil mixing element made of soil mortar, which is erected or formed in the ground after the mixing tool has been removed, can, for example, harden into a foundation element, in particular a foundation pile.

[0028] The inventive method enables the production of a particularly well-mixed and thus highly homogeneous soil mortar with increased matrix strength directly in the ground, which hardens into a high-quality structural element. The risk of defects forming in the foundation element is significantly reduced or even completely eliminated. Furthermore, the use of crushed construction debris can substitute for other granular building materials and, in addition to increased strength, contribute to solving ecological and economic environmental problems.

[0029] The invention is further explained below with reference to a preferred embodiment. The drawings show:

[0030] Fig. 1 shows a side view of a construction machine in the form of a drilling rig with a mixing device according to the invention;

[0031] Fig. 2 shows a side view of a tool used in the mixing device of Fig. 1, here in the form of a drilling tool;

[0032] Fig. 3 shows a perspective view from above of an alternative tool that can be used with the mixing device according to the invention;

[0033] Fig. 4 shows a schematic representation of the method according to the invention; and

[0034] Fig. 5 shows a schematic representation of a modification of the inventive method as a two-phase system with a modified mixing device. Fig. 1 shows a carrier device 1 in the form of a drilling rig, on which the inventive mixing device 40 is inserted and attached. It should be noted, however, that the drilling rig shown here, as an example of a self-propelled construction machine, represents only one exemplary application for a carrier device 1, and that the mixing device 40 can also be used as a carrier device in other construction machines and in stationary drilling rigs.

[0035] The carrier device 1 can comprise a mast 20 on which a drive carriage 22 can be mounted so as to be movable in the longitudinal direction of the mast 20. The drive carriage 22 can carry a rotary drive 43 of the mixing device 40 for driving a mixing rod 41, which here is designed as a drill string. Because the mixing device according to the invention does not necessarily have to be designed in such a way that the entire borehole must be created in the ground with it, but can also be used to create a soil mixing element in a borehole that has been at least partially prepared beforehand, the more general disclosure refers to a "mixing rod", which is explained using the drill string as an example.

[0036] The carrier device 1 can have a chassis 10, which may include an undercarriage 12 and a superstructure 14 preferably rotatably mounted thereon. The mast 20 can be pivotally mounted on the superstructure 14. By means of a swivel cylinder 18, the mast 20 can be pivoted from a substantially vertical operating position to a substantially horizontal transport position. A winch 15 can be arranged on a lower section of the mast 20, which receives a cable 17 leading to a pulley 16 located in the upper section of the mast 20. The mast 20 can also have a mast head 24. In its operating position, the mast 20 can be located at a front section of the chassis 10. On the front of the mast, that is, on a side facing away from the landing gear 10, the mast 20 can have a guide device 26, on which the drive carriage 22 can be guided and moved along the mast 20.The guide device 26 preferably comprises guide rails 30 arranged laterally in a front region of the mast 20. The drive carriage 22 can have several guide jaws 32, 33 which slidably engage with the guide rails 30. The drive carriage 22 can thus support the mixing device 40, whose rotary drive 43 is provided for rotating the mixing rod 41. The mixing device 40 can therefore also be referred to as a drilling drive assembly if it is provided with a drilling tool 42 at its lower end. For the purposes of the invention, a release function and a mixing function are sufficient for the tool, which is why it is not limited to a drilling tool 42 as shown here by way of example.

[0037] The rotary drive 43 of the mixing device 40 can have at least one drive motor unit (not shown in detail here) for generating and providing motor torque. A gearbox converts the drive torque and drive speed into a higher or lower speed and transmits it to the drill or mixing rod and, via the rod, to the tool. A universal joint can be flanged to the rotary drive 43 for this purpose. This universal joint is designed to accommodate the drill or mixing rod and transmits the provided output torque to drive the drill or mixing rod. It should be noted that the universal joint is only used in certain situations, particularly when an angular misalignment between the longitudinal axes of an output shaft and the drill or mixing rod needs to be bridged and compensated. Therefore, it can be omitted in other applications and arrangements.For guiding and / or holding the drill string, a rod guide 48 is provided below the rotary drive 43 and, if applicable, the cardan joint, which is attached to the mast 20.

[0038] The mixing device 40 thus comprises the tubular mixing rod 41 with at least one (not shown in detail here) inner feed line, the tool 42 arranged at the lower end of the mixing rod 41, which is designed (at least) for loosening and mixing soil material and has at least one outlet opening 47 which is connected to the at least one inner feed line, and the rotary drive 43 for rotating the mixing rod 41 with the tool 42 attached to it for creating a mixing area in the soil.

[0039] According to the invention, a receiving device 44 (not shown in detail) for receiving a granular bulk material is formed on an upper region of the mixing rod 41, and a first inner feed line is formed and dimensioned to convey the received granular bulk material from the receiving device 44 through the mixing rod 41, specifically through the first inner feed line, to at least one first outlet opening 47 in the region of the tool 42, from which the bulk material exits and is homogeneously mixed with the soil material by the rotating tool as aggregate in the mixing zone. After solidification (for example, by hardening), the columnar or lamellar soil mixing element 60 is formed in the soil from this mixing zone (see Fig. 5).

[0040] The first inner feed line serves as a material feed pipe and can, for example, be designed as a liner pipe located inside the mixing rod 41, or it can be a segment of the mixing rod's internal volume. In any case, the inner diameter of the first inner feed line must be dimensioned so that the granular bulk material of the selected size or particle size can pass through without becoming entangled and blocking the cross-section.

[0041] Clogging of the first inner feed line by the aggregates can also be prevented, for example, by utilizing the vibrations of the vibrator or the boom, as in deep vibratory compaction. For this purpose, a vibratory drive can also be arranged to convey the bulk material in the first inner feed line and / or in the tool 42.

[0042] The mixing rod 41 can further comprise at least a second feed line for supplying a liquid or suspension to the tool 42 and / or at least a third feed line for supplying a gas, in particular air, for conveying the bulk material in the first inner feed line and / or in the tool 42. The second feed line can therefore be used to supply a binder suspension to the mixing area, as is already known in the prior art of EP 4 101 987 A1, in order to produce the soil mortar in situ by homogeneous mixing with the soil material and the granular bulk material in the mixing area. The gas can be used to loosen the mixing area and / or to support the smooth transport of the bulk material through the first feed line. The distinction between the second and third feed lines serves to describe their function.Where possible, these feed lines can be used for fluids and gases and can even be identical. As a rule, the second and / or third feed line will have a smaller cross-section than the first inner feed line for the granular bulk material.

[0043] In the mixing devices shown in Figures 4 and 5, the receiving device 44 for the bulk material can include a storage device 45, in particular a bulk material hopper, to receive a larger quantity of bulk material and introduce it into the first inner feed line. The capacity of the storage device 45 is dimensioned such that it can preferably hold the quantity of bulk material required to construct a bottom mixing element in order to enable a continuous process. The receiving device 44 can be arranged above or below the rotary drive.

[0044] In the variants of the mixing device shown in Figs. 4 and 5, the storage device 45 is attached to the drive carriage 22 and is mounted to be displaceable along the mast 20, so that the storage device 45 together with the mixing rod 41, the tool 42 and the rotary drive 43 is moved into the depth of the ground and is raised along the mast when the tool is withdrawn, whereby the bulk material can be fed into the receiving device 44.

[0045] In the variant shown in Fig. 4, the storage device 45 can also be mounted independently of the mixing rod 41 and tool 42 by means of its own slide along the mast to allow, if necessary, refilling with bulk material during the mixing process (see Fig. 1).

[0046] In the variant shown in Fig. 5, in addition to the storage unit 45 (here with a slightly smaller volume than in Fig. 4), a feed unit 46 in the form of a tipping bucket is provided. This feed unit is mounted independently of the mixing rod 41 and tool 42 on its own sliding carriage along the mast and can be filled by a construction machine in a lower position on the mast. After being raised to the storage unit 45, it can empty its contents into it. This allows, for example, an interruption of the mixing and feeding process to be avoided even when larger quantities of bulk material are required, as the feed unit 46 repeatedly moves up and down along the mast while the mixing process continues by rotating the mixing rod. Furthermore, in this variant, filling the receiving unit 44 or the storage unit 45 is also possible with small equipment such as a wheel loader.

[0047] The tool 42, arranged at the lower end of the mixing rod, of which two variants are shown by way of example in Figs. 2 and 3, has both loosening elements 50, in particular teeth, for loosening soil material, and mixing elements 51 for mixing loosened soil material with the supplied bulk material and / or supplied liquid and / or supplied gas.

[0048] In the variant shown in Fig. 2, the release elements 50 and the mixing elements 51 are rigidly attached at axial intervals to a drill shank 52 of the tool and are rotated around the drill shank. The release elements 50 and the mixing elements 51 can also be mounted to rotate relative to each other, as shown in Fig. 3, so that, for example, relative rotation in opposite directions is possible.

[0049] Furthermore, the tool 42 has several outlet openings 47 that communicate with the at least one first internal feed line and / or the at least one second feed line, if present, and / or the at least one third feed line, if present. These outlet openings are dimensioned such that the substance supplied by the feed line can pass through it and enter the mixing area, where the substances are mixed with each other and with the dissolved soil material by the mixing elements 51.

[0050] A tool 42 that can be used in the mixing device according to the invention is, for example, the drilling tool 49 described in EP 4 101 987 A1. This tool is shown in Fig. 3 and comprises a tubular drill shaft 52 with an inner cavity. A central pilot tip 53 and a downwardly directed removal device 54 are arranged on the underside of the drill shaft 52. The removal device 54 has a drill helix 55. Tooth-like removal elements 57 for removing soil material are arranged along two radially extending support bars 56 in a generally known manner. The removal elements 57 serve here as release elements 50. The support bars 56 are hollow and form a conduit that runs in the radial direction.The conduit channel is connected to a supply line in the hollow drill shaft 52 for the delivery of a liquid or suspension from the (second) supply line, which runs through the mixing rod 41. The liquid or suspension can flow out via (second) outlet openings (not shown) along the support ribs 56 and be introduced directly into the borehole at the removal device 54, for example, during rotation of the drill bit 49 in the feed direction. This allows the soil material to be loosened to a final depth and liquefied in the mixing zone.

[0051] A coupling-like drill pipe connection 58 is arranged at one upper end of the drill shaft 52 to connect the drill bit 49 to the hollow drill or mixing rod 41, which, as described, is rotatably mounted on the carrier device 1 and driven to rotate. Liquid or suspension can be supplied from the carrier device to the drill bit 49 via the drill or mixing rod 41, specifically the second supply line.

[0052] Between the drill pipe connection 58 and the removal device 54, axially and / or radially offset mixing elements 51 with radially directed support arms are formed on the drill shaft 52, on which mixing blades can be arranged.

[0053] Generally, a drilling tool can only have a removal device for soil material at its lower end. However, under certain soil conditions, it may be advantageous to have at least one removal device at the lower end of the drill shank and at least one further removal device axially above the lower removal device, for example, at the upper end of the drilling tool. This ensures that soil material that has fallen in along the borehole wall can be reliably removed, even when the drilling tool is withdrawn. The (second) outlet openings are then preferably located on and / or between the two removal devices.

[0054] Furthermore, the tool can be equipped with an adjusting device that directs the supply of liquid or suspension to different (secondary) outlet openings depending on the phase of the mixing process. For example, when creating and sinking a borehole with the drilling tool 49, the adjusting element can be positioned so that, during drilling, the drilling fluid or drilling suspension is directed to lower (secondary) outlet openings and introduced directly into the borehole at the lower removal device 54. Conversely, if the drilling tool 49 is withdrawn from the created borehole with the reverse direction of rotation, the adjusting element can cause the supplied liquid or suspension to be introduced partially or exclusively into the borehole via higher (secondary) outlet openings at the upper removal device.By introducing the fluid at the upper end of the drilling tool, it is ensured during retraction that the rotating drilling tool mixes the newly introduced fluid or suspension sufficiently intensively with the existing suspension in the borehole and the loosened soil material.

[0055] When the tool is withdrawn after reaching the final depth, the bulk material is also discharged as aggregate from the previously filled storage device 45 via the inner feed line, for example in the form of a liner tube, and the associated at least one first outlet opening 47 in the area of ​​the tool, preferably above at least the lower removal device 54, and fed into the mixing area, where it is mixed into the mixture of loosened soil material and, if applicable, suspension by renewed mixing during the withdrawal process by the mixing elements 51, preferably with simultaneous rotation of the tool in the opposite direction of rotation as in the preceding drilling process, so that the column- or lamellar soil mixing element 60 is formed in the soil.

[0056] If a larger quantity of aggregate is added when the tool is withdrawn, it may be necessary to remove at least some of the loosened soil material from the mixing area while the granular bulk material is fed into the mixing area.

[0057] In a further development of the inventive method, it can also be particularly advantageous to introduce a curable suspension as a fluid, for example by supplying a binder, in particular a cement suspension, into the mixing area, so that after the tool is withdrawn from the ground, the soil mortar produced from the excavated soil material and the supplied curable suspension can harden with the granular bulk material additionally mixed in therein, for example to form a foundation element, in particular a foundation pile.

[0058] As part of the process, for example, the settling of the added granular bulk material in the column can be prevented by appropriately dimensioning the grain size and / or the amount of additive, as well as by adjusting the suspension density.

Claims

B 3894 PATENT CLAIMS 1 Mixing device (40) for creating a column- or lamellar soil mixing element (60) in the soil, comprising a tubular mixing rod (41) with at least one internal feed line, a tool (42) arranged at a lower end of the mixing rod (41) which is designed for loosening and mixing soil material and has at least one outlet opening (47) which is connected to the at least one internal feed line, and a rotary drive (43) for rotating the mixing rod (41) with the tool (42) attached thereto for creating a mixing area in the soil, characterized in that a receiving device (44) for receiving a granular bulk material is formed at an upper region of the mixing rod (41), and that a first internal feed line is formed.to guide the received granular bulk material from the receiving device (44) through the mixing rod (41) to at least one first outlet opening (47) to form the column- or lamellar soil mixing element (60) in the soil. Mixing device (40) according to claim 1, characterized in that a carrier device (1) with a mast (20) is provided, along which the rotary drive (43) is slidably mounted by means of a drive carriage (22).

3. Mixing device (40) according to claim 2, characterized in that a feed device (46) for feeding granular bulk material to the receiving device (44) is slidably mounted along the mast (20).

4. Mixing device (40) according to one of claims 1 to 3, characterized in that the mixing rod (41) has at least one second supply line for supplying a liquid or a suspension to the tool (42).

5. Mixing device (40) according to one of claims 1 to 4, characterized in that the mixing rod (41) has at least a third supply line for supplying a gas, in particular air, for conveying the bulk material in the first inner supply line and / or in the tool (42).

6. Mixing device (40) according to one of claims 1 to 5, characterized in that the receiving device (44) for the bulk material has a storage device (45), in particular a bulk material bunker.

7. Mixing device (40) according to one of claims 1 to 6, characterized in that a vibrating drive for conveying the bulk material is arranged in the first inner feed line and / or in the tool (42).

8. Mixing device (40) according to one of claims 1 to 7, characterized in that the tool (42) has loosening elements (50), in particular teeth, for loosening soil material and mixing elements (51) for mixing loosened soil material with the supplied bulk material and / or supplied liquid and / or supplied gas. -19- 9. Mixing device (40) according to claim 8, characterized in that the dissolving elements (50) and the mixing elements (51) are rotatably mounted relative to each other.

10. Mixing device (40) according to one of claims 1 to 9, characterized in that the tool has several outlet openings (47) which communicate with the at least one first inner feed line and / or the at least one second feed line, if present, and / or the at least one third feed line, if present.

11. Method for creating a column- or lamellar-shaped soil mixing element in the ground, using a mixing device (40), in particular according to one of claims 1 to 10, with a tubular mixing rod (41) having at least one internal feed line, a tool (42) arranged at a lower end of the mixing rod (41) by which soil material is loosened and mixed in the ground, wherein the tool (42) has at least one outlet opening (47) which is connected to the at least one internal feed line, and a rotary drive (43) by which the mixing rod (41) with the tool (42) attached thereto is driven in a rotary motion to create a mixing area in the ground, characterized in that a receiving device (44) is formed on an upper region of the drill string (41) into which a granular bulk material is fed for receiving, and that a first internal feed line is formed.by which the granular bulk material is conveyed from the receiving device (44) through the mixing rod (41) to at least one first outlet opening (47) to form, of the columnar or lamellar soil mixing element (60) is directed into the soil.

12. Method according to claim 11, characterized in that the dissolved soil material is at least partially removed from the mixing area, while granular bulk material is fed into the mixing area.

13. Method according to claim 11 or 12, characterized in that a binder, in particular cement suspension, is supplied to the mixing area, which is mixed in the mixing area with dissolved soil material and the granular bulk material to form a soil mortar, which hardens in the soil to form the soil mixing element (60).

14. Method according to one of claims 11 to 14, characterized in that the granular bulk material fed into the receiving device (44) is a material with a grain size of up to 100 mm, preferably from 2 mm to 70 mm, in particular gravel and / or crushed construction waste.

15. Use of granular bulk material with a grain size of up to 100 mm, preferably from 2 mm to 70 mm, in particular crushed construction waste, for creating a columnar or lamellar soil mixing element (60) in the soil, in particular in a mixture with dissolved soil material and a binder, in particular a cement suspension.

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