GB2538769A

GB2538769A - Screw pile

Info

Publication number: GB2538769A
Application number: GB1509163.0A
Authority: GB
Inventors: Kiss Paul
Original assignee: Abbey Pynford Holdings Ltd
Current assignee: Abbey Pynford Holdings Ltd
Priority date: 2015-05-28
Filing date: 2015-05-28
Publication date: 2016-11-30
Also published as: GB201509163D0

Abstract

A screw pile system 1 and method of use thereof, comprising a screw pile 2, the screw pile having a hollow stem 3 providing a passage 4 for a settable fluid 5, the stem 3 having at least one helical plate 11, 12 fixed about the stem 3, the screw pile 2 further comprising at least one aperture 13 to 15 associated with the or each plate 11, 12, the at least one aperture 14, 15 being in fluid connection with the passage 4 of the stem 3 and positioned so that, in use, settable fluid 5 within the passage 4 can be ejected through the at least one aperture 14, 15 into a region 19 behind a trailing edge 16 of the or each helical plate 11, 12.

Description

Screw Pile The present invention relates to a screw pile system and a method for using the same, particularly, but not exclusively, the invention relates to a screw pile system for use in constructing foundations.

Screw piles typically comprise a longitudinal stem with one or more helical plates, where the stem is rotated to cause the screw pile to be screwed into the ground. The screw pile is normally left in the ground with an upper part of the screw pile remaining above the ground to be used as a structural support anchored by a lower part with the helical plate or plates. This may then be used, for example, as foundations for a building or similar structure. However rotation of the or each helical plate as the screw pile penetrates the ground may disturb the ground and this is normally in one of two ways.

In clay type soils, a cavity may be formed into which the soil subsequently relaxes reducing the load carrying capacity of the pile. In chalk soils, behind a trailing edge of each helical plate, the rotating helical plates may compromise the integrity of the chalk causing it to fragment, again reducing the load carrying capacity.

According to the present invention there is provided a screw pile system comprising a screw pile having a stem and at least one helical plate fixed about the stem, the system being arranged to eject a fluid behind the trailing edge of the at least one helical plate as the helical plate is screwed into the ground.

The present invention may enable the fluid, for example settable material such as a cement based grout to fill any cavity in the soil created by the associated rotating helical plate, or into any ground surrounding the screw pile, the integrity of which has been compromised by the rotating helical plate. Thus the addition of the settable material may maintain or increase the integrity of the ground surrounding the screw pile and thus increase the stability and load carrying capacity of the screw pile when it is anchored in the ground.

The invention may also be employed to increase the load carrying capacity of screw piles used in granular and non-cohesive materials, where a settable fluid may be used to 'cement' together the grains or non-cohesive material to form a rock like substance.

The screw pile system may further comprise: a screw pile, the screw pile having a hollow stem providing a passage for a fluid, the stem having at least one helical plate fixed about the stem, the screw pile further comprising at least one aperture associated with the or each helical plate, the at least one aperture being in fluid connection with the passage of the stem and positioned so that, in use, fluid within the passage of the stem can be ejected through the at least one aperture into a region behind a trailing edge of the or each helical plate as the screw pile is screwed into the ground.

The present invention allows fluid, for example a settable cement based grout, or other settable fluid, to be ejected out of the hollow stem of the screw pile as the screw pile is screwed into the ground.

In one embodiment, the or each aperture is located in the wall of the stem aligned with a trailing edge of an associated helical plate. This causes the fluid that is ejected from each aperture to fill any void in the ground created at the trailing edge of each helical plate during rotation of the screw pile, or to be distributed into any disturbed ground in this region. More preferably, each aperture is located in the stem where the trailing edge of the helical plate meets the stem.

In an alternative embodiment, the screw pile system may further comprise at least one pipe having one or more apertures positioned along the trailing edge of the or each associated helical plate, which at least one pipe and aperture are in fluid connection with the passage of the stem. This can be particularly advantageous as the fluid may be more evenly distributed behind the trailing edge.

The system is preferably arranged to eject fluid from the at least one aperture as the screw pile is screwed into the ground.

Preferably, the screw pile is arranged to remain in the ground once it has been screwed into the ground.

The screw pile system may comprise at least two or more helical plates spaced along the stem, each helical plate having at least one aperture associated therewith.

The stem may have a closed distal end to cause fluid in the stem to be ejected out of the at least one aperture.

The screw pile system may further comprise a rotation unit to, in use, rotate the screw pile to screw the screw pile into the ground and a fluid swivel, for receiving fluid from an external source and conveying the fluid into the passage of the stem. The volume of fluid can be measured and the load capacity can be determined by the torque of the rotation unit. This ensures adequate information is provided to screw the screw pile into the ground with a sufficient volume of fluid ejected into the ground.

The screw pile system may further comprise a pump for pumping fluid into the stem. The pump may cause pressurised fluid to travel through the hollow stem and out of the apertures and may be used to control the rate at which fluid is ejected.

The screw pile system may further comprise at least one closure means associated with at least one of the one or more apertures to prevent ejection of fluid from the one or more associated apertures. This may prevent fluid being ejected from apertures that are not in the ground. The closure means may be arranged to be manually opened, or opened by contact with the ground.

The closure means may be a bung or may comprise a cover plate associated with an associated aperture to prevent fluid being ejected out of the associated one or more apertures until the bung or cover plate contacts the ground. The cover plate may be pivotally attached to the stem.

The or each cover plate is preferably arranged so that, in use, as the stem rotates and is drawn into the ground, the or each cover plate is forced by the ground to rotate into an open position, to allow the fluid to pass out of the associated one or more apertures. This ensures that fluid can only be ejected from the associated one or more apertures once the associated aperture is below ground level.

The screw pile system may further comprise a hollow extension portion to be fixed, by a joint portion, to the top of the screw pile, once the screw pile has been screwed into the ground; the hollow extension portion being arranged to be in fluid connection with the passage of the stem of the screw pile; the rotation unit and fluid swivel being connected to the extension portion, so that the screw pile may be screwed further into the ground as fluid is received by the extension portion from the fluid swivel, to be passed through the joint into the passage of the stem of the screw pile and ejected out through the apertures.

This permits the screw pile to be screwed into the ground with a top portion left above the ground, the hollow extension portion fixed to the top portion to enable the screw pile to be screwed deeper into the ground, whilst settable fluid can pass through the joint portion, connecting the extension portion and screw pile, so that the settable fluid may be ejected out through the apertures. The top of the extension portion may then remain above the ground once the rotation unit and fluid swivel have been removed, to form or support the foundations of a building or similar structure.

The screw pile preferably has a length of between 4 to 8 metres and the extension portion preferably has a length of between 2 to 4 metres. The screw pile and/or extension portion may be provided with a mounting plate or bracket, so that when the screw pile, or screw pile and extension portion, are fixed in the ground, the mounting plate or bracket provides further support during construction of a building or similar structure.

According to a second aspect of the present invention there is provided a method of constructing foundations, the method comprising: rotating a screw pile into the ground, the screw pile having a hollow stem providing a passage for settable fluid, the stem having at least one helical plate fixed to the stem and at least one aperture associated with the or each helical plate, the at least one aperture being in fluid connection with the passage of the stem, the method comprising passing settable fluid down the passage of the stem and out of the or each aperture at the same time as rotating the screw pile into the ground, so that at least one helical plate draws the screw pile into the ground and the settable fluid is ejected through at least one aperture into a region behind a trailing edge of the at least one helical plate so that the fluid fills the space or spaces created in the ground disturbed by the at least one rotating helical plate, the method further comprising leaving the screw pile in the ground and using the screw pile as a structural support for a building or similar structure.

Several embodiments of the present invention will now be described, by way of example only, with reference to the accompanying figures, of which: Figure 1 discloses one embodiment of a screw pile system in accordance with the present invention; Figure 2 illustrates the screw pile system of Figure 1 in position screwed into the ground; Figure 3 is a close up view of a screw pile with a bung closure means; Figure 4 is a close up view of a screw pile with a cover plate closure means; Figure 5 is an alternative embodiment in accordance with the present invention; Figure 6 illustrates a screw pile system with an additional extension portion.

Referring to Figure 1 a screw pile system, indicated generally as 1, in accordance with the invention comprises a screw pile 2. The screw pile 2 has a hollow stem 3 providing a passage 4 for receiving settable cement based grout 5, where one end of the stem 3 is connected to a rotation unit 6 for rotating the screw pile 2 and the other, distal, end of the stem 3 is closed. A fluid swivel 7 is located on the stem 3, which fluid swivel 7 receives the grout 5 from conduit 8. The conduit 8 receives the grout under pressure from a pump 9.

The screw pile 2 has helical plates 11, 12 fixed about the stem 3, each helical plate 11, 12 having an associated aperture 14, 15 in fluid connection with the passage 4 of the stem 3 and positioned where a trailing edge 16 of each helical plate 11, 12 meets the stem 3. The apertures 14, 15 are temporarily closed by the respective bungs 17, one of which is shown in greater detail in Figure 3. When the screw pile 2 is screwed into ground 18, each bung 17 is forcibly removed from the associated aperture 14, 15 when it contacts the ground 18, so that the grout 5 within the passage 4 of the stem 3 may then be ejected through that aperture 14,15 into a region behind the trailing edge 16 of the associated helical plate 11, 12 as it passes through the ground.

The pump 9 and rotation unit 6 are operated together to cause the screw pile 2 to be screwed into the ground 18 at the same time as the grout 5 is ejected from the apertures 14, 15. As shown in Figure 2, the grout 5 then enters the regions 19 of the ground 18 behind the trailing edge 16 of each helical plate 11, 12 and fills any spaces created in the disturbed ground 19.

Once in the ground 18, the screw pile 2 is detached from the rest of the screw pile system 1, with the top of the screw pile 2 extending above ground 18 ready to be used as a structural component in the foundations of a building or similar structure.

Referring to Figure 4, a close up of an alternative closure means for each aperture 14, 15 is shown, whereby the closure means is in the form of a cover plate 20. The cover plate 20 as shown in Figure 34 covers the associated aperture 14, 15 and is pivotally mounted to the stem 3 so that, in use, when the cover plate 20 meets the ground 18, the cover plate 20 rotates to an open position, so that grout 5 may be ejected through the associated aperture 14, 15.

As an alternative to the use of bungs 17 or cover plates 20, the pump 9 need not be energised until the last helical plate 10 enters the ground 18 and thus no grout 5 is ejected until all the apertures 14, 15 are in the ground 18.

An alternative embodiment of a screw pile 2 is illustrated in Figure 5, whereby a pipe 21 having a plurality of apertures 22 are positioned along the trailing edge 24 of a helical plate 23, so that the pipe 21 and apertures 22 are in fluid connection with the passage 4 of the stem 3. The fluid may then be ejected out of the apertures 22 into the region behind the trailing edge 24 of the helical plate 23.

Referring now to Figure 6, a screw pile system 1 having a hollow extension portion is shown. The extension portion 25 is attached, with a joint portion 26, to the top portion of the screw pile 2, whereby a passage 27 in the hollow extension portion 25 is in fluid connection with the passage 4 of the stem 3 in the screw pile 2, so that, in use, the screw pile 2 may be screwed further into the ground 18 as the grout 5 passes from the passage 27 of the hollow extension portion 25 through the joint portion 26, into the passage 4 of the stem 3 of the screw pile 2 and out through the apertures 14, 15.

The above embodiments of the present invention have been described by way of example only and it will be apparent to those skilled in the art that modifications may be made without departing from the scope of the appended claims.

Claims

Claims 1. A screw pile system comprising a screw pile having a stem and at least one helical plate fixed about the stem, the system being arranged to eject a fluid behind the trailing edge of the at least one helical plate as the helical plate is screwed into the ground.
2. A screw pile system as claimed in Claim 1, the screw pile having a hollow stem providing a passage for a fluid, the stem having at least one helical plate fixed about the stem, the screw pile further comprising at least one aperture associated with the or each helical plate, the at least one aperture being in fluid connection with the passage of the stem and positioned so that, in use, fluid within the passage of the stem can be ejected through the at least one aperture into a region behind a trailing edge of the or each helical plate as the screw pile is screwed into the ground.
3. A screw pile system as claimed in Claim 2, wherein the or each aperture is located in the wall of the stem and is aligned with a trailing edge of an associated helical plate.
4. A screw pile system as claimed in Claim 2, wherein each aperture is located in the stem where the trailing edge of the helical plate meets the stem.
5. A screw pile system as claimed in Claim 2, further comprising at least one pipe having one or more apertures positioned along the trailing edge of an associated helical plate, which at least one pipe and one or more apertures are in fluid connection with the passage of the stem.
6. A screw pile system as claimed in any one of Claims 2 to 5 comprising two or more helical plates spaced along the stem, each helical plate having at least one aperture associated therewith.
7. A screw pile system as claimed in anyone of Claims 2 to 6, wherein the stem has a closed distal end.
8. A screw pile system as claimed in anyone of Claims 2 to 7, further comprising a fluid swivel, for receiving fluid from an external source and conveying the fluid into the passage of the stem.
9. A screw pile system as claimed in anyone of Claims 2 to 8, further comprising a pump for pumping fluid into the stem.
10. A screw pile system as claimed in anyone of Claims 2 to 9, further comprising at least one closure means associated with at least one of the one or more apertures to prevent ejection of fluid.
11. A screw pile system as claimed in Claim 10, wherein the closure means is arranged to be manually opened.
12. A screw pile system as claimed in Claims 10 or 11, wherein the closure means comprises at least one cover plate associated with at least one of the one or more apertures to prevent fluid being ejected out of the associated one or more apertures until the cover plate enters the ground.
13. A screw pile system as claimed in Claim 12, wherein the cover plate is pivotally attached to the stem.
14. A screw pile system as claimed in Claim 12 or 13, wherein the or each cover plate is arranged so that, in use, as the stem rotates and is drawn into the ground, the or each cover plate is forced by the ground to rotate into an open position, to allow the fluid to pass out of the associated one or more apertures into the ground.
15. A screw pile system as claimed in any one of claims 10 or 11 wherein the closure means comprises a bung in at least one aperture.
16. A screw pile system as claimed in anyone of Claims 2 to 15, further comprising a hollow extension portion to be fixed, by a joint portion, to the top of the screw pile, once the screw pile has been screwed into the ground; the hollow extension portion being arranged to be in fluid connection with the passage of the stem of the screw pile; the rotation unit and fluid swivel being connected to the extension portion, so that the screw pile can be screwed further into the ground as fluid is received by the extension portion from the fluid swivel, which fluid is to be passed through the joint into the passage of the stem of the screw pile and ejected out through the apertures.
17. A screw pile system as claimed in any preceding claim, wherein the screw pile is arranged to remain in the ground once it has been screwed into the ground.
18. A screw pile system as claimed in any preceding claim, further comprising a rotation unit to, in use, rotate the screw pile to screw the screw pile into the ground.
19. A screw pile system as claimed in any preceding claim, further comprising a settable fluid which, in use, is conveyed along the passage of the stem and out of the at least one aperture.
20. A screw pile system as claimed in Claim 19, wherein the settable material is a cement based grout.
21. A screw pile for a screw pile system as claimed in any preceding claim.
22. A method of piling, the method comprising screwing a screw pile into the ground and injecting a settable material behind the trailing edge of a helical plate of the screw pile.
23. A method of constructing foundations, the method comprising the method Claim 22 including: rotating a screw pile into the ground, the screw pile having a hollow stem providing a passage for settable fluid, the stem having at least one helical plate fixed to the stem and at least one aperture associated with the or each helical plate, the at least one aperture being in fluid connection with the passage of the stem, the method further comprising passing settable fluid down the passage of the stem and out of the or each aperture at the same time as rotating the screw pile into the ground, so that at least one helical plate draws the screw pile into the ground and the settable fluid is ejected through at least one aperture into a region behind a trailing edge of the at least one helical plate so that the fluid fills the space created in the ground disturbed by the at least one rotating helical plate, the method further comprising leaving the screw pile in the ground and using the screw pile as a structural support for a building or similar structure.
24. A screw pile system substantially as described with reference to and/or as illustrated in one or more of the accompanying drawings.
25. A method of constructing foundations substantially as described with reference to and/or as illustrated in one or more of the accompanying drawings.