EP0253988A1 - Prefabricated concrete element and method for introducing such an element to the soil - Google Patents

Abstract

For drilling a prefabricated hollow, tube-like or stake-like concrete element (12) into the soil, a central axial clearance (30) of the same is formed with an unround cross-section. A drilling tool (14) having a correspondingly unround cross-section is inserted into this clearance (30) and assumes torque transfer to the tip of the concrete element (12). <IMAGE>

Description

The invention relates to a prefabricated pile or tubular concrete part and a method for introducing such into the ground.

In "Construction machinery and technology", 9th year, 1962, pages 253ff. a concrete pile is specified, which is provided on the outside with a helical rib arrangement. In this way, like a screw, the concrete pile can be placed in the ground quickly and without too much noise.

In order for the concrete pile to be able to safely transmit the torques to be applied from the driven pile end to the front pile end, a specially designed reinforcement is proposed in the main application. This reinforcement can also take on static tasks when the pile is set.

For some applications, however, it is not necessary that a concrete part still has to withstand high loads after penetrating the soil, e.g. when it is a hollow concrete pile, which essentially serves only as a lost formwork, into which in-situ concrete and the necessary reinforcement is placed, or when a hollow concrete part is to serve as a section of a pipeline. In this case, the concrete part would then have to receive an expensive reinforcement, which is only required during the screwing into the ground, but is oversized or even completely unnecessary for the intended permanent use of the pile.

The present invention is intended to develop a prefabricated concrete part in accordance with the preamble of claim 1 in such a way that it is buried in the ground without expensive reinforcement can be screwed in richly.

This object is achieved according to the invention by a concrete part according to claim 1.

When using the concrete part according to the invention, a screwing tool is inserted into the non-circular cross-section in the central axial recess, which can be subjected to high torsion. Since this tool is used repeatedly, higher tool costs can be accepted.

Via the positive connection between the circumferential surface of the screwing tool and the circumferential wall of the axial recess of the concrete part, the necessary screwing-in moments are transmitted without any great stress on the material of the concrete part: The torque transmission takes place predominantly or exclusively via the screwing tool.

The development of the invention according to claim 2 is advantageous with regard to avoiding linear contact between the screwing tool and the concrete part, with regard to an edge-free inner surface of the concrete part and with regard to a good absorption of ring stresses.

The development of the invention according to claim 5 is advantageous with regard to a low weight, easy handling and low manufacturing costs of the insertion tool.

If a concrete part is brought into the ground according to claim 6, part of the displaced ground can be taken up via the interior of the screwing tool.

• Figur 1: Eine seitliche Ansicht eines Betonrohres sowie eines mit ihm zusammenarbeitenden Eindrehwerkzeu­ges, teilweise axial geschnitten;
• Figur 2: Einen transversalen Schnitt durch das Betonrohr nach Figur 1 in vergrößertem Maßstab; und
• Figur 3: Einen transversalen Schnitt, ähnlich zu Figur 2, durch ein abgewandeltes Betonrohr.

The invention is explained in more detail below on the basis of exemplary embodiments with reference to the drawing. In this show:

• Figure 1: A side view of a concrete pipe and a screwing tool working with it, partially cut axially;
• Figure 2: A transverse section through the concrete pipe of Figure 1 on an enlarged scale; and
• Figure 3: A transverse section, similar to Figure 2, through a modified concrete pipe.

A dam 10 is indicated in FIG. 1, through which a pipeline having a large diameter is to be laid. This is done using a prefabricated concrete pipe, generally designated 12, which positively receives a screwing tool, generally designated 14, which is rotated around its axis (arrow 18) using an only schematically indicated drive head 16 and is advanced along its axis (arrow 20) .

As can be seen from FIG. 1, the concrete pipe 12 has an essentially cylindrical outer surface 22, on which a helical rib 24 is formed. The latter has an essentially triangular cross section and gives the concrete pipe 12 the property of a self-tapping screw in the ground. At its front end, located on the right in FIG. 1, the concrete pipe has a tip 26 which displaces the soil and which - as shown - can be provided with a cutting edge 28.

As can be seen in particular from FIG. 2, the concrete pipe 12 has an internal axial recess 30 which extends from the rear end of the concrete pipe 12 in FIG. 1 to the tip 26 thereof. The recess 30 has a cross-sectional area that is delimited by an ellipse. In practice, the ratio of the ellipse half axes is between 0.7 and 0.9.

The outer contour of the transverse cross-sectional area of the screw-in tool 14 corresponds to a small clearance fit, taking into account the usual surface roughness of prefabricated concrete parts and the dirt on the surface of the screw-in tool 14 which cannot be avoided in practice. This means that the outer surface of the screwing tool 14 comes into substantial flat contact with the inner wall of the recess 30 after rotation by a small angle. In this way, the power transmission between the screwing tool 14 and the concrete pile 12 is distributed in the circumferential direction, and mainly ring stresses and radial loads are generated in the material of the concrete pipe 12, which the concrete pipe 12 can absorb due to its shape.

The screwing tool 14 is in turn a hollow cylinder with an elliptical cross section, the wall thickness of the screwing tool 14 being chosen so large that the torque transmission to the tip of the concrete pipe 12 takes place predominantly or exclusively via the screwing tool. In this way, the various sections of the concrete pipe 12 lying axially one behind the other are largely freed from the task of torque transmission.

Because the insertion tool 14 is hollow, not only is its weight kept small, which is advantageous both in terms of ease of use and in view of low manufacturing costs, and one can also pass through the interior of the insertion tool 14 from the top of the concrete pipe Take up 12 accumulating soil when the concrete pipe 12 is formed with an open end in a modification of the embodiment shown in Figure 1.

Although this is not shown in the drawing, it goes without saying that the drive head 16 can be moved along the desired tube axis by a corresponding slide. When the concrete pipe 12 is screwed into the ground, in the exemplary embodiment considered here the dam 10, the angular speed and the feed speed of the drive head 16 are coordinated with one another in a manner corresponding to the slope of the rib 24. If the concrete pipe 12 has been screwed into the ground to the desired length, in the exemplary embodiment considered here, it has been completely screwed through the dam 10, then the rotary movement of the drive head 16 is terminated and the screwing tool 14 is removed from the concrete pipe in the opposite direction by arrows 20 in the opposite direction 12 pulled out. After removal of the tip 26, one then has a piece of pipeline crossing the dam 10, which can be connected to conventional external lines. As can be seen from FIG. 2, this piece of pipeline then has a smooth internal cross section, which is well suited for the conveyance of contaminated liquids.

FIG. 3 shows a transverse section through a modified concrete pipe, in which the inner axial recess 30 has a hexagonal cross section. This modified concrete pipe is used together with a correspondingly modified screwing-in tool which has a hexagonal cross section matching the recess 30.

It goes without saying that, analogously to that described above for concrete pipes, vertical or inclined concrete piles can also be set, wherein after pulling out the screwing tool into the recess 30 a reinforcement can be inserted and then the entire recess can be filled with in-situ concrete, so one To produce composite piles with high static load-bearing capacity, in which the original, prefabricated concrete pile fulfills the function of lost formwork and anchoring in the ground.

It also goes without saying that, instead of a single pile or pipe-like concrete part, it is also possible to use a plurality of pile or pipe segments placed axially one behind the other, the individual segments being able to be connected to one another in a manner known per se from borehole linings by threaded connections or bayonet connections. In this case, the screwing-in tool is expediently composed of segments of the same length, which in turn are held together via torque-transmitting, releasable connections and are each applied in accordance with the progress of the introduction of the segments. In this case, axially somewhat deformable compensating elements are preferably inserted between the individual pile or tube segments, while cooperating stops on the successive tool segments ensure that the successive segment outer surfaces are exactly aligned with one another, so that the entire insertion tool is unhindered from the several segments composite pile or tube can be pulled out.

Claims (8)

1. Prefabricated pile or tubular concrete part for introduction into the ground, which is provided at least on a part of its outer surface with a helical rib arrangement and optionally has a reinforcement, characterized in that it has a large part of its axial extent, preferably over its whole Has longitudinal central axial recess (30) which has a non-circular cross-section. 2. Concrete part according to claim 1, characterized in that the recess cross-section has a smooth continuous closed boundary line, preferably an oval, an ellipse or egg shape. 3. Concrete part according to claim 2, characterized in that the recess cross-section is limited by a polygon, in particular a hexagon. 4. A method for introducing a concrete part according to any one of claims 1-3 in the ground, in which the concrete part is aligned at the point of introduction in the desired manner and then rotated about its longitudinal axis while simultaneously performing an axial feed movement in the ground, characterized in that A screwing tool (14), preferably made of steel, which can withstand high torsion, is inserted into the axial recess (30) and extends essentially over the entire length of the recess (30) and has a drive (16) that generates the rotary and feed movement. is coupled. 5. The method according to claim 4, characterized in that a hollow screwing tool (14) is used. 6. The method according to claim 5, characterized in that a concrete part (12) is used with an open front end. 7. The method according to any one of claims 4-6, characterized in that after screwing in a first segment of the concrete part using a correspondingly long tool segment, further concrete part segments and tool segments of the same length are attached and screwed in such that the tool segments overall have an aligned, continuous outer surface have and the butt joints between concrete part segments and tool segments are in common planes. 8. The method according to claim 7, characterized in that the tool segments have cooperating stops, the engagement of which ensures the alignment of the segment outer surfaces, and axially deformable compensating pieces are inserted between the concrete part segments.

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