METHOD AND DEVICE FOR ARRANGEMENT OF A FOUNDATION PILE IN THE GROUND

Description

BACKGROUND OF THE INVENTION

[0001] The invention relates to a method and device for arranging a foundation pile in a soil.

[0002] It is known to realize foundation piles in a soil by means of the screw injection process. A tube consisting of tube segments and provided with a screw blade and pile tip at the distal end, is then first urged into the soil in a rotating fashion. During this process grout is discharged from an aperture situated near the pile tip. The discharged grout mixes with dislodged soil material and forms a grout shell around the tube. Once the pile tip has reached the wanted depth a reinforcement cage is placed in the tube and the tube is filled with concrete.

[0003] The screw injection method allows foundation piles to be arranged into a soil in a vibration-free fashion. It is advantageous that the grout shell can increase the load bearing capacity of the pile.

[0004] Although such foundation piles have proven their worth in practice, there is a lasting need for a (further) increase of the load bearing capacity to be provided by the foundation piles, so that fewer piles are required for a structure to be built.

[0005] KR 101 135 163 B1 discloses a grout injecting and replacing device and a construction method of a concrete foundation pile using the same.

[0006] JP S57 92218 A discloses a method in which an injection tube is inserted into a casing, and a boring liquid is supplied from the injection tube and injected from the tip, during which excavation is continued while normally turning the casing. When the shoe reaches a given depth, the turning of the casing is stopped and then the injection of the boring liquid is stopped. Then, a ready-made pile is inserted into the casing and cement mortar is charged through the injection tube to harden the root of the pile. The casing C is then reversely turned, and the casing is gradually pulled out while pushing soil and sand into the surrounding area of the pile by the blade of the casing.SUMMARY OF THE INVENTION

[0007] It is an object of the invention to provide a method for arranging a foundation pile in a soil according to a controlled screw injection process with which the foundation pile to be realized is capable of obtaining a high design load bearing capacity.

[0008] It is an object of the invention to provide a tube assembly for a foundation pile for a screw injection process with which the foundation pile to be realized is capable of obtaining a high design load bearing capacity.According to one aspect the invention provides

[0009] According to a first aspect, the invention provides a tube assembly for forming a foundation pile according to claim 1.

[0010] In that way an increased pressure can be realized in the vicinity of the drill head. In case of a downwardly moving drill tip, the cross-plate as it were ensures a downward driving of the grout-soil material mixture created. As a result, the mixing action in the area below the cross-plate can be enhanced. Furthermore, penetration of the grout into open spaces between the grains of as yet undisturbed soil material can be enhanced, which may be advantageous to the drilling process and to the formation of the mixture. After installation, the surface of the cross-plate can be included in the load bearing capacity calculations.

[0011] The lips can be situated at the location of the apertures and form a guide means towards the apertures. The lips can be formed in a simple manner from the material of the cross-plate. This may for instance be done by locally cutting through the cross-plate and bending out areas of the cross-plate adjacent to the cut-throughs, to the distal side. The cut-throughs can extend in radial and possibly in tangential direction as well, in particular up into the circumferential edge of the cross-plate.

[0012] When projected onto a plane of projection transverse to the tube center line, the lips can at least largely cover the apertures.

[0013] In a further development of the tube assembly, the drill head comprises a drill blade and at least one cutter retained thereon, wherein the drill blade is provided with the passage, wherein the passage preferably opens to the outside with a directional component in distal direction, in one embodiment combined with a directional component in outward radial direction. The outlet of the passage can be situated immediately behind the cutter in rotation direction, wherein in distal direction the cutter extends beyond the outlet.

[0014] In one embodiment, the drill blade is plate-shaped and extends diametrically across the drill head, parallel to the axial plane of the tube, and it has edges extending in distal and radial inward direction, from which respective cutters extend in distal and tangential direction.

[0015] As stated above, the drill head can be rotation-fixed with the tube, may be attached thereto, wherein the tube can be made of steel and form the exterior surface of the tube assembly.

[0016] Alternatively, the tube assembly can comprise a hollow prefabricated concrete pile, which forms the exterior surface of the tube assembly. The drill head can then be attached for rotation to a drilling rod extending through the hollow pile.

[0017] In a further development, at the proximal side of the drill head, or at the proximal side of the cross-plate if the cross-plate is present, the tube is provided with at least one strip extending circumferentially and in proximal direction, extending radially to the outside. It can form a so-called helical plate / mixing blades, which is known per se of screw injection piles.

[0018] According to a further aspect, the invention provides an arrangement for creating a foundation pile in a soil according to claim 5.

[0019] According to a further aspect, the invention provides a method for arranging a foundation pile in a soil according to claim 6.

[0020] In an embodiment, during introducing the tube assembly into the soil a grout-soil material mixture passes through the apertures from the distal side of the cross-plate to its proximal side in order to form a grout shell around the tube.

[0021] In an embodiment, the lips, due to the rotation of the lips, exert a mixing action on the dislodged soil material and the grout.

[0022] Mixing is enhanced if the drill head is rotated so that the lips extend obliquely in rotation direction.

[0023] If in the tube assembly used, the lips are situated at the location of the apertures and the drill head is rotated, the lips can guide the mixture situated below the cross-plate to the distal side of the cross-plate.

[0024] In a preferred embodiment, use is made of the aforementioned tube assembly, wherein, when projected onto a plane of projection transverse to the tube center line, the lips at least largely cover the apertures. As a result, despite the presence of the apertures in the cross-plate, nearly the entire surface area of the cross-plate can be effective in transferring vertical forces and be included in the load bearing capacity calculations.

[0025] In a further development of the method according to the invention, the drill head comprises a drill blade and a cutter retained by it extending in distal direction thereof, wherein the passage is arranged in the drill blade and preferably - considered in rotation direction - debouches behind the cutter. In that way, while the grout flows through the passage in the drill blade, it is able to cool the part that retains the cutter, the drill blade. This is advantageous, as the temperature at the drill blade may become higher than the temperature (in the order of 30 degrees) at which the grout could solidify / thicken, during which formation of lumps might occur which could hamper the mixture formation and the flow-through of mixture through the cross-plate.

[0026] In an embodiment thereof, the passage opens to the outside with a directional component in distal direction, wherein the grout is pressed out of the passage with a downward directional component so that the grout penetrates soil material situated straight below the drill head.

[0027] In that way mixing grout with soil material in particular sand, can be enhanced, which is advantageous to the strength of a grout shell formed around the tube and to the load bearing capacity of the soil area below the foundation pile formed.

[0028] In particular, the grout can be pressed out of the passage with a distal and a radial directional component so that the grout also penetrates the soil material situated obliquely sideways below the rotating drill head.

[0029] In a further development of the method according to the invention, once it has been established that the drill head has been introduced into the soil at the wanted depth, the rotation of the drill head is stopped but pressing the grout out of the passage is continued with, with a downward directional component, at a third pressure that is raised, in particular raised multiple times, relative to the first pressure range. That way, grout can be urged into the open spaces between the grains of the soil material (in particular sand) in a relatively large soil area, next to and below the drill head, as a result of which the load bearing capacity as finally realized, is further increased. The cross-plate can then be functional in hampering an upward run of the grout, thus enhancing the dispersion in sideward and downward direction.

[0030] The first pressure range can be in the order of 5-20 bar, preferably in the order of 10-15 bar. The pressure imposed in the first pressure range may increase with the depth in a track, in order to keep the discharged flow rate of grout per unit of insertion length nearly constant, at a constant introduction speed, in view of the formation of a grout shell around the tube that has a uniform thickness in tube direction. The third pressure can be in the order of 50-150 bar, preferably approximately 100 bar. The pressures / pressure ranges used and grout flow rates discharged can be selected in dependence on the condition / composition of the soil as determined beforehand.

[0031] In one embodiment, wherein the soil comprises one or more sandy strata as first track sections and one or more clayey and / or peaty strata as second track sections, the drill head is rotated at a higher speed during passing through the first track sections than it is during passing through the second track sections, and during passing through the second track sections the grout is pressed out of the drill blade at a pressure in a second pressure range that is lower than the first pressure range. When passing through a clay stratum or peat stratum, rotation will be minimal and much less grout will be discharged. At those locations, the relatively thin grout shell will predominantly serve as protection against corrosion at the tube.

[0032] The method according to the invention can be applied to several types of pile foundations.

[0033] In a first embodiment, the tube including drill head is rotated. The tube may be made of steel and form the exterior surface of the tube assembly during introduction into the soil, wherein downward forces and rotational forces are transferred to the drill head by means of the tube.

[0034] In a second embodiment, the tube assembly comprises a hollow pile, in particular a prefab concrete pile, which pile forms the exterior surface of the tube assembly during introduction, wherein a rotationally driven drilling rod extends through the lumen of the pile and is attached to the drill head.

[0035] In both cases, in the condition in which the drill head is at the wanted depth, the interior space of the tube can be provided with a reinforcement and filled with concrete. The tube remains in the soil, fixedly connected to the cross-plate that may be attached to the lower end of the tube and closes off the interior space downward.BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The invention will be elucidated on the basis of an exemplary embodiment shown in the attached drawings, in which: Figures 1A-F show an oblique distal view, an oblique proximal view, a first side view, a second side view, a cross-section according to IE, and an end view, respectively, of a drill head for a tube assembly according to the invention; Figures 2A-F show consecutive stages of introducing a tube assembly according to the invention into a soil; and Figure 3 shows a schematic view of a condition in which the tube assembly has been brought at depth and reinforcement has been placed therein. DETAILED DESCRIPTION OF THE DRAWINGS

[0037] The drill head 10 shown in Figures 1A-F comprises a centrally located drill blade 11, which is substantially V-shaped in side view and bears two cutters 12a, 12b. The drill blade 11 is composed of three steel plates 11a, 11b and a plate 11c situated in between them, which plates are permanently connected to each other to form one unity. The plates 11a and 11b each have one free oblique edge 15a, 15b and at the other oblique edge 17a, 17b are extended by a cutter 12a, 12b forming a unity with the plate 11a, 11b in question. The plate 11c has two oblique edges 15c that are level with the oblique edges 15a, 15b, respectively.

[0038] The cutters 12a, 12b have been turned in opposite direction such that in operational condition they are both oriented in rotation direction A. The cutters have a cutting edge 13a, 13b which in this example is provided with notches 14a, 14b.

[0039] The drill blade 11 is permanently attached to a cross-plate 20, which is permanently attached to the distal end of a tube 30. The cross-plate 20 is perpendicular to the center line S of the tube 30. The cross-plate 20 has a circumferential edge 24 from which the cross-plate 20 is cut through by arcuate cut-throughs 23 at locations that are regularly spaced apart, which cut-throughs extend radially inward, having a tangential directional component, up to the circumference of the tube 30. At the location of arcuate, more or less radial fold lines 25, lips 21 are bent out towards the distal side of the cross-plate 20, so that apertures 22 are formed in the cross-plate 20, regularly distributed along the circumference. The lips 21 all extend in rotation direction as well. In figures 1E and 1F it can be seen that in projection, the cross-plate 20 including lips 21 form an almost continuous circular surface.

[0040] Inside the tube 30, a chamber 40 is arranged on the cross-plate 20, an aperture 42 connecting said chamber at proximal side to a supply line 41 for grout. At the distal side of the chamber 40 it is in fluid communication with passages 16a, 16b extending in the plate 11c and debouching in both edges 15c, in distal and radial outward direction. A ball that is not shown, is situated within the chamber 40, which ball acts as a one-way valve for allowing grout to pass through in distal direction but stopping it in proximal direction.

[0041] In figures 1C and 1D the drill head 10 can be seen as part of a tube assembly 1, including tube 30 and grout supply line 41. At the exterior surface of the tube 30 two strips 31a, 31b are attached, each extending along half a tube circumference, obliquely, in proximal direction and in counter-rotational direction.

[0042] The tube assembly 1 can be deployed in a manner as illustrated on the basis of Figures 2A-F. The tube assembly 1 is intended for being part of a foundation pile in soil 100. The soil 100 here consists of for instance a top stratum 102, adjacent to the surface level, a clay stratum 103 and a sand stratum 104.

[0043] In figure 2A, a bottom part of a tube assembly 1 is held vertical by means of an installation, that is not shown, including a king post. The tube is engaged by a rotary drive on the installation and is urged downward, from the installation, so that the tube 30 including drill head 10 is both rotated in direction A and moved downward, direction B, to pass through the top stratum 102. In figure 2B the tip of the drill head 10 has arrived at the clay stratum 103 and the grout pump on the installation is activated. The grout pump is then set at a second flow rate, and is thus set at a related (second) (operational) pressure range.

[0044] The drill head 10 and tube 30 are rotated at a first speed A1. Via supply line 41, direction L1, chamber 40, aperture 42 and passages 16a, 16b the grout is discharged from the drill head 10 to the clay stratum, directions D1. The grout and the clay are mixed to a limited extent here, most of the grout travels through the apertures 22 with respect to the downwardly moving drill head 10 in order to form a grout shell 113 between the tube 30 and the clay stratum 103, see figure 2C.

[0045] The tube 30 is built up from tube segments, each time the proximal end of a tube segment has arrived near the surface level 101 a next tube segment is coupled to it and brought into engagement with the linear and rotational drives.

[0046] When the drill head 10 has arrived at the sand stratum 104, the rotational speed (A2) is increased as is the grout flow rate to be delivered by the grout pump. The grout is now supplied per unit of introduction length at a higher flow rate, at a first (operational) pressure within a first pressure range, which pressure is higher than the aforementioned (second) pressure, through the supply line 41 in direction L2 and discharged behind the respective cutters 12a, 12b at a higher force in distal and radial outward directions D2. Said discharged grout may have an agitating effect on the sand body and is capable of penetrating into the pores between the sand grains and as a consequence cause a softening effect. The cutters 12a, 12b dislodge the sand from the sand stratum, the rotating drill blade 11 ensures that the sand mixes with the grout. The cross-plate 20 exerts a downward driving influence on the grout-sand mixture, which can be advantageous to the penetration into the sand body of the grout discharged at a lower level.

[0047] The imposed pressure in the first pressure range may increase as the depth in a track increases, in order to keep the discharged flow rate of grout per unit of insertion length almost constant, in view of a regular grout shell thickness around the tube, when considered in tube direction. The same applies to the second pressure in the second pressure range. The first and second pressure ranges may overlap in part, depending on the composition of the soil present in the respective tracks.

[0048] The lips 21 extending downward and in rotation direction, increase the degree of mixing. Relative to the drill head 10 that moves downwards, the grout-sand mixture ultimately travels through the apertures 22 in the cross-plate 20 and forms a relatively thick grout shell 114 around the tube 30, see figures 2D and 2E.

[0049] During introducing the tube assembly 1 into the soil, the strips 31a, 31b that rotate along ensure some mixing of the material of the grout shell and the immediate surroundings. The strips 31a, 31b function as a so-called helical plates.

[0050] The grout flowing through the drill blade 11 has a cooling effect on the material it is made of, as a result of which the temperature can remain as low as not to solidify / thicken the grout and formation of lumps is prevented.

[0051] Once the drill head 10 has arrived at the wanted depth in the sand stratum 104 the grout pump is operated at a third operational pressure, which is multiple times the operational pressure relative to the first pressure range, to press the grout in direction L3 through the supply line 41 to the drill head 10. At that location, the grout is squirted at great force out of the passages 16a, 16 in distal and in radial outward directions D3. The drill head 10 can then be rotated a few times at relatively low speed, optionally in opposite direction.

[0052] The cross-plate 20 hampers an upward travel of the grout now discharged. The grout penetrates into the sand body along a considerably distance, see figure 3.

[0053] Once the grout supply has stopped and the installation has been disconnected from the upper tube segment, the grout supply line 41 can be disconnected from the chamber 40 and a reinforcement cage 50 can be lowered into the interior space 32 of the tube 30. Subsequently the interior space 32 can be filled with concrete in order to substantially finish the foundation pile.

[0054] As can be seen in figure 3, by far the largest part of the grout-compacted area is situated below the cross-plate. This part can be included in the calculation of the load bearing capacity of the foundation pile. The surface area of the cross-plate, when considered in projection on a horizontal plane, can also be included in said calculation as the cross-plate forms a stable, substantially horizontal foundation surface.

[0055] The oblique position of the cutters furthermore provides more surface area for transfer of forces (vertical).

[0056] The shape and size of the apertures in the cross-plate is determined experimentally. Prior to a job, soil-drilling tests have provided an insight into the composition of the soil and as a consequence the soil material.

[0057] The drill blade provides freedom of choice in terms of the location of additional discharge apertures for grout.

Claims

1. Tube assembly (1) for forming a foundation pile, comprising a tube (30) having a tube center line (S), which tube (30) forms an interior space (32), wherein at the distal end or introduction end of the tube (30) a drill head (10) is situated, wherein the drill head (10) is provided with at least one passage (16a, 16b) that opens to the outside and is capable of being brought into fluid communication with the interior space (32), wherein at the distal end of the tube (30) and at the proximal side of the drill head (32) a cross-plate (20) is arranged, in particular attached to the drill head (10), which extends in radial outward direction relative to the tube center line(S) to outside of the tube (30) and forms a circumferential flange, wherein the cross-plate (20) is provided with apertures (22) forming a passage for a flow of mixture of grout and soil material from the distal side of the cross-plate (20) to its proximal side, and said tube assembly for forming a foundation pile being characterized in that the tube assembly (1) is provided with lips (21) extending from the cross-plate (20) in distal direction and in rotation direction for providing a mixing action on soil material dislodged by the drill head (10) and the grout, wherein the lips (21) are formed by regularly spaced apart, arcuate cut-throughs (23) cutting through the cross-plate (20), wherein the lips (21) extend obliquely from the cross-plate (20) in distal and tangential direction and, at the location of arcuate, more or less radial fold lines (25), are bent out towards the distal side of the cross-plate (20), so that the apertures (22) are formed in the cross-plate (20), regularly distributed along the circumference.

2. Tube assembly (1) according to claim 1, wherein the lips (21) are situated at the location of the apertures (22) and form a guide means towards the apertures (22) wherein the apertures (22) open in radial direction in the circumferential edge (24) of the cross-plate (20) and wherein, when projected onto a plane of projection transverse to the tube center line (S), the lips (21) at least largely cover the apertures.

3. Tube assembly (1) according to claim 1 or 2, wherein the drill head (10) comprises a drill blade (11) and at least one cutter (12a, 12b) retained thereon, wherein the drill blade (11) is provided with the passage (16a, 16b), wherein the passage (16a, 16b) preferably opens to the outside with a directional component in distal direction, in one embodiment combined with a directional component in outward radial direction, wherein, preferably, the outlet of the passage (16a, 16b) is situated immediately behind the cutter (12a, 12b) in rotational direction, wherein in distal direction the cutter (12a, 12b) extends beyond the outlet and / or, wherein, preferably, the drill blade (11) is plate-shaped and extends diametrically over the drill head (10), parallel to the axial plane of the tube (30), and having edges extending in distal and radial inward direction, from which respective cutters (12a, 12b) extend in distal and tangential direction.

4. Tube assembly (1) according to claim 1, 2 or 3, wherein the drill head (10) is attached to the tube (30), wherein the tube (30) is made of steel and forms the exterior surface of the tube assembly (1), or wherein the tube assembly (1) comprises a hollow prefab concrete pile, which forms the exterior surface of the tube assembly (1), and / or wherein, preferably, at the proximal side of the cross-plate (20), the tube (30) is provided with at least one strip (31a, 31b) extending circumferentially and in proximal direction, extending radially to the outside.

5. Arrangement for creating a foundation pile in a soil (100), comprising a tube assembly (1) according to any one of the -claims 1 - 4 and a device for urging the tube assembly (1) into the soil (100) and rotating it around the tube center line (S), a supply of grout and a device for pressing grout from the supply into the interior space of the tube (30) in order to press the grout out of the passage in the drill blade (11).

6. Method for arranging a foundation pile in a soil (100) using the tube assembly (1) according to any one of claims 1 - 4, wherein the method comprises the following steps: - providing the tube assembly (1), wherein the drill head (10) is provided with at least one cutter (12a, 12b), - introducing the tube (30) with the rotating drill head (10) at the lower end into the soil (100), according to an introduction track, wherein the at least one cutter (12a, 12b) of the rotating drill head (10) dislodges soil material, - during at least one first section of the introduction track via the interior space pressing grout towards the passage (16a, 16b) in the drill head (10) at a first pressure or pressures in a first pressure range, - pressing the grout out of the passage to enable the grout to mix with the soil material, in particular sandy soil material, dislodged by the drill head (10), - wherein the relative displacement of grout or mixture of grout with soil material is limited in proximal direction by the cross-plate (20).

7. Method according to claim 6, wherein during introducing the tube assembly (1) into the soil (100) a mixture of grout-soil material passes through the apertures (22) from the distal side of the cross-plate (20) to its proximal side in order to form a grout shell around the tube (30), wherein, preferably, the lips (21) exert a mixing action on the dislodged soil material and the grout, wherein, preferably, wherein the drill head (10) is rotated so that the lips (21) extend obliquely in rotation direction.

8. Method according to claim 6 or 7, wherein in the tube assembly (1) used, when projected onto a plane of projection transverse to the tube center line (S), the lips (21) at least largely cover the apertures (22).

9. Method according to any one of claims 6, 7 or 8, wherein the drill head (10) comprises a drill blade (11) and a cutter (12a, 12b) retained by it extending in distal direction thereof, wherein the passage (16a, 16b) is arranged in the drill blade (11) and - considered in rotation direction - debouches behind the cutter (12a, 12b), wherein, preferably, the passage (16a, 16b) opens to the outside with a directional component in distal direction, wherein the grout is pressed out of the passage (16a, 16b) with a downward directional component so that the grout penetrates soil material situated straight below the drill head (10), wherein, preferably, with a distal and a radial directional component the grout is pressed out of the passage (16a, 16b) so that the grout also penetrates the soil material situated obliquely sideways of said material below the rotating drill head (10).

10. Method according to any one of claims 6 - 9, wherein the first pressure range is in the order of 5-20 bar, preferably in the order of 10-15 bar.

11. Method according to any one of claims 6 - 10, wherein once it has been established that the drill head (10) has been introduced into the soil (100) to the wanted depth, the rotation of the drill head (10) is stopped but pressing the grout out of the passage (16a, 16b) is continued with, with a downward directional component at a third pressure that is raised, in particular raised multiple times, relative to the first pressure range, wherein, preferably, the third pressure is in the order of 50-150 bar, preferably approximately 100 bar.

12. Method according to any one of claims 6 - 11, wherein the soil (100) comprises one or more sandy strata as first track sections and one or more clayey and / or peaty strata as second track sections, wherein during passing through the first track sections the drill head (10) is rotated at a higher speed than during passing through the second track sections, wherein during passing through the second track sections the grout is pressed out of the drill head (10) at a second pressure in a second pressure range that is lower than the first pressure range.

13. Method according to any one of claims 6 - 12, wherein the tube including the drill head (10) is rotated, the tube (30) preferably being made of steel and during introduction into the soil (100) forming the exterior surface of the tube assembly (1), wherein downward forces and rotational forces are transferred to the drill head (10) by means of the tube (30).

14. Method according to any one of the claims 6 - 12, wherein the tube assembly (1) comprises a hollow pile, in particular a hollow prefab concrete pile, which hollow pile forms the exterior surface of the tube assembly (1) during introduction, wherein a rotationally driven drilling rod extends through the lumen of the hollow pile and is attached to the drill head (10).

15. Method according to any one of claims 6 - 14, wherein in the condition in which the drill head (10) is at the wanted depth, the interior space of the tube (30) is provided with a reinforcement and filled with concrete.