SOIL-DISPLACEMENT DRILL AND METHOD FOR FORMING A SMOOTH FOUNDATION PILE WITH SUCH A SOIL-DISPLACEMENT DRILL

Abstract

The present disclosure relates to a soil displacement drill comprising a drill pipe; a widening at one end of the drill pipe that is provided with (1) a screw blade for screwing the drill into the substrate, and (2) an outlet opening for the passage of material that is introduced for forming the foundation pile; and a flap that is movable between a first position for allowing unhindered screwing of the drill into the substrate and a second position for preventing the material from entering a screw groove. The screw groove is formed in the substrate by the screw blade during unscrewing of the drill from the substrate. The disclosure further relates to a method for forming a smooth foundation pile using such a drill.

Claims

1. Soil-displacement drill for soil-displacing drilling into a substrate for forming a foundation pile, comprising: a drill pipe with a pipe casing with a first outer diameter (D.sub.1); and a widening which is configured as a displacer and for this: has an outer casing with a second outer diameter (D.sub.2) which is greater than the first outer diameter (D.sub.1) of the drill pipe; is provided at one end of the drill pipe, and has an end remote from this drill pipe (5); and which furthermore is provided with a screw blade which protrudes relative to the outer casing for screwing the drill into the substrate, and has an end which is arranged at said end of the widening; and is provided with an outlet opening for the passage of material that is introduced into the drill pipe for forming the foundation pile; characterized in that the drill has a flap which is arranged below the widening and is movable between: a first position in which the flap is arranged in a zone out of line with the screw blade and below the widening; and a second position in which said flap is arranged below the widening with an area which is at least as large as the greatest cross-section of the screw blade, between the outlet opening and said end of the screw blade.

2. Drill according to claim 1, wherein the flap is pivotably attached to the widening.

3. Drill according to claim 2, wherein the flap is positioned such that, in unhindered state when the drill is erected with the widening below the drill pipe, said flap hangs down in its second position.

4. Drill according to claim 2, characterized in that the flap is positioned such that, when the drill is screwed into a substrate, said flap is held in its first position by the substrate.

5. Drill according to claim 1, characterized in that the screw blade has a maximum thickness (d) which is between 15 mm and 100 mm.

6. Drill according to claim 1, wherein the widening is provided with at least one second screw blade which protrudes relative to the outer casing for screwing the drill into the substrate, and has an end which is arranged at said end of the widening and is provided with at least one second flap which is arranged below the widening and is movable between: a first position in which this second flap is arranged in a zone out of line with the second screw blade and below the widening; and a second position in which said second flap is arranged below the widening with an area which is at least as large as the greatest cross-section of the second screw blade, between the outlet opening and said end of the second screw blade.

7. Method for forming a smooth foundation pile in a substrate by means of a soil-displacement drill comprising a drill pipe and a widening which is attached to an end of the drill pipe, wherein the drill is drilled into the substrate, wherein material for forming the foundation pile is introduced into the drill pipe, and wherein the drill is withdrawn from the substrate, wherein the drill is a drill according to claim 1, that during drilling of the drill into the substrate, the flap remains in its first position and that on withdrawal of the drill from the substrate, the flap remains in its second position.

8. Method according to claim 7, wherein, on withdrawal of the drill from the substrate, the drill is screwed out of the substrate with a speed which is lower than the speed of the screw blade.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0063] In this description, by means of reference signs, reference is made to the appended drawings in which:

[0064] FIG. 1 shows an embodiment of a soil-displacement drill according to at least one embodiment of this disclosure in perspective, with a single-use drill tip and with the flap in its first position;

[0065] FIG. 2 shows the drill from FIG. 1 in perspective, without the single-use drill tip and with the flap in its second position;

[0066] FIG. 3 shows the drill from FIG. 1 in a front view, with single-use drill tip and with the flap in its first position;

[0067] FIG. 4 shows the drill from FIG. 1 in perspective, without the single-use drill tip and with the flap in its second position;

[0068] FIG. 5 shows in various stages how a foundation pile can be formed with the soil-displacement drill;

[0069] FIG. 6 shows a second embodiment of a soil-displacement drill according to at least one embodiment of this disclosure in perspective;

[0070] FIG. 7 shows a third embodiment of a soil-displacement drill according to at least one embodiment of this disclosure in perspective.

DETAILED DESCRIPTION

[0071] The soil-displacement drills (1) shown each comprise a drill pipe (4), a widening (5) and a flap (8).

[0072] The drill pipe (4) is in each case configured so as to be substantially cylindrical and is provided with a widening (5) at the bottom at one end (16). A screw blade (6), which protrudes with respect to the outer casing of the widening (5), is arranged on said widening (5). In the embodiments shown, the screw blade (6) is in each case arranged on the bottom half of the widening (5). One end (18) of the screw blade (6) is arranged at an end (17) of the widening (5) which is remote from the drill pipe (4). In the second embodiment illustrated, the drill (1) is provided with a second screw blade (14) which is arranged on the widening (5), twisted through 180° relative to the first screw blade (6). This second screw blade (14) is furthermore identical to the first screw blade (6) and is also arranged with one end (19) on said end (17) of the widening (5).

[0073] The maximum outer diameter (D.sub.2) of the outer casing of the widening (5) is situated at the height of the screw blade (6) and is greater than the outer diameter (D.sub.1) of the outer casing of the drill pipe (4) above this widening (5). The screw blade (6) has a constant outer diameter (D.sub.3) which is greater than the outer diameter (D.sub.2) of the outer casing of the widening (5).

[0074] The screw blade (6) has a maximum thickness (d) which is between 50 mm and 100 mm. Even more preferably, said maximum thickness (d) is less than 70 mm, and extremely preferably less than or equal to 30 mm.

[0075] A cylindrical cavity (12) extends through the entire drill pipe (4) and opens below the widening (5) into an outlet opening (7) for the passage of material (9) which is introduced into the cylindrical cavity (12) for forming a foundation pile (3).

[0076] In some cases, the drill pipe (4) may be provided with one or more secondary spirals (screw blades) on the inside or outside.

[0077] The drill pipe (4), the widening (5) and the screw blade (6) may for example be made of metal, for example steel. The screw blade (6) may be attached to the widening (5) by welding.

[0078] In the first embodiment depicted, a single-use drill tip (11) is provided at the bottom end (17) of the widening (5).

[0079] This single-use drill tip (11) is not attached to the widening (5) but is arranged thereon so that the drill (1) can bore into the substrate (2) and at that moment is held against the widening (5) by the substrate (2).

[0080] This single-use drill tip (11) may also be made of metal.

[0081] As an alternative to this single-use drill tip (11), the soil-displacement drill (1) may also be provided with one or more closing flaps which are pivotably attached to the bottom of the widening (5) for closing the outlet opening (7).

[0082] At the level of each screw blade (6, 14) and next to said end (18, 19) of the screw blade (6, 14), a corresponding flap (8, 15) is pivotably attached to the widening (5) at the bottom of the widening (5).

[0083] This flap (8, 15) is moveable between: [0084] a first position as shown in FIGS. 1 and 3, in which this flap (8, 15) is arranged such that it allows the unhindered screwing of the drill (1) into the substrate (2); and [0085] a second position as shown in FIGS. 2, 4, 6 and 7, in which this flap (8, 15) is arranged below the widening (5) with an area which is at least as large as the greatest cross-section of the corresponding screw blade (6, 15), between the outlet opening (7) and said end (18, 19) of the corresponding screw blade (6, 14), such that this flap (8, 15) prevents the material (9) that is introduced into the cylindrical cavity (12) from entering the screw slot, which was formed in the substrate by the screw blade (6, 14), when the drill (1) is unscrewed from the substrate (2).

[0086] In order to allow the unhindered screwing of the drill (1) into the substrate (2) in the first position, each flap (8, 15) is arranged in a zone out of line with the corresponding screw blade (6, 14). In the first and second embodiments illustrated, said flap (8) is arranged against the casing of the widening (5). Alternatively but less preferably, for this for example the flap (8) may also rest against the outer surface of the single-use tip (11), as in the third embodiment illustrated. As another alternative, the flap (8) could for example be designed as a shut-off valve for closing the outlet opening (7) in the widening (5).

[0087] FIG. 5 shows in various stages how, by means of a soil-displacement drill (1) according to at least one embodiment of this disclosure, drilling can be performed in a substrate (2) in order to form a foundation pile (2).

[0088] The drill (1) is brought in the known manner by means of a crane (13) to the location at which a foundation pile (3) is to be formed. The single-use tip (11) is arranged at the bottom against the widening (5) of the drill (1) in order to close off the outlet opening (7) and form a drill tip for the drill (1) (step A).

[0089] The drill (1) is lowered and drills into the substrate (2) in the direction of the screw blade (6) (step B). During drilling into the substrate (2), the substrate (2) holds the single-use tip (11) against the widening (5). The soil is displaced sideways at the level of the widening (5). The desired drill depth is safely achieved with a soil-displacement drill (1) according to at least one embodiment of this disclosure because the screw blade (6) is at the bottom, i.e. on the widening (5).

[0090] When the drill (1) has reach the desired drill depth, a steel reinforcement (11) may be introduced into the drill pipe (step C) and the drill pipe (4) is then filled with filler material (9), such as for example concrete (step D).

[0091] The drill (1) is then unscrewed against the direction of the screw blade (6), with a speed which is slower than the speed of the screw blade (6) of this drill (1) (step E). This speed may be selected sufficiently slow to at least partially reclose the screw slot in the substrate (2) that is formed by the screw blade (6), but may remain sufficiently large to unscrew the drill pipe (4) from the substrate (2) rapidly. When the drill (1) is unscrewed, the single-use tip (11) is detached and thus remains in the bottom of the drilled hole. The filler material (9) and the reinforcement (10) are discharged through the outlet opening (7) under force of gravity so as to form the foundation pile (3) (step F)