GB2351517A

GB2351517A - Piling arrangement

Info

Publication number: GB2351517A
Application number: GB9913481A
Authority: GB
Inventors: Roger Alfred Bullivant
Original assignee: Roxbury Ltd
Current assignee: Roxbury Ltd
Priority date: 1999-06-11
Filing date: 1999-06-11
Publication date: 2001-01-03
Also published as: GB9913481D0

Abstract

A ground piling arrangement 10 comprises an elongate pile 12 and a tip member 14 that, when viewed longitudinally, extends beyond the cross-sectional outline of the pile over at least part of the periphery of the pile. The pile may be square in section, made of concrete, solid or hollow, or may incorporate reinforcement, and may be integral with the tip or attached to it. The tip, offset up to 45 degrees from the pile, may also be square in section, made of concrete, reinforced, and may taper down to point 20. The attachment of the tip to the pile may be by means of a spigot and socket 22. Driving of the pile tip leads to a square hole of increasing size until the offset pile section extends the hole into an eight-pointed star shape (see figure 2). The circumference of the tip may be extended by spiral or circumferential ribs.

Description

2351517 Piling Arranizement The present invention relates to piling

arrangements and to methods of piling.

When driving a pile into the ground, skin friction between the surface of the pile and the surrounding ground can result in significant loss of energy from the piling operation. The friction increases as the pile penetrates deeper into the ground.

The present invention provides a piling arrangement comprising a pile and a tip member at the lowermost end of the pile, the tip member having an outline, when viewed along the length of the pile, which extends beyond the outline of the pile over at least part of the periphery of the pile.

The pile and tip member may be integral or connected.

The pile and tip member may have a polygonal outline, the outline of the tip member being out of register with the outline of the pile, whereby to extend beyond the pile outline, as aforesaid. The pile and tip member may have substantially the same shape outline. The outline of the tip member may be out of register with the outline of the pile by one half of the angle subtended at the centre of the pile by the edges of the pile member. The pile and tip member are preferably substantially rectilinear in outline; and are preferably out of register by about 45'. The tip member and pile may be square in section.

The tip member may be larger in section than the pile. The tip member may taper down from the portion at which the tip member meets the pile. The tip member may carry rib means which project beyond the outline of the pile, as aforesaid. The rib means may be circumferential or spiral.

The invention further provides a method of piling, in which a pile is provided with a tip member at its lowermost end, the tip member having an 2 outline, when viewed along the length of the pile, which extends beyond the outline of the pile, over at least part of the periphery of the pile.

The pile and tip member may be in accordance with any of the features of the first aspect of the invention.

Examples of the present invention will now be described in more detail, by way of example only, and with reference to the accompanying drawings, in which:

Fig. 1 is a schematic vertical view of a piling arrangement being driven; and Fig. 2 is a horizontal section, on an enlarged scale, through the arrangement of Fig. 1, at the line II-II in Fig. 1.

Fig. I shows a piling arrangement 10, comprising a pile 12 and a tip member provided at the lowermost end of the pile 12. The tip member 14 has an outline, as will be described, which extends beyond the outline of the pile 12 over at least part of the periphery of the pile 12, when viewed along the length of the pile.

In more detail, the piling arrangement 10 includes an elongate pile 12, which may be square in section (as shown in Fig. 2) and may be made of concrete. The pile 12 may be solid or hollow and may incorporate reinforcement, suchas rebars extending along its length. In Fig. 1, the pile 12 is shown partially driven into the ground 16, with a hammer 18 or other driving arrangement shown schematically in position to drive the pile 12 further.

The tip 14 is provided at the lowermost end of the pile 12. The tip 14 is also square in outline, as can be seen from Fig. 2. However, the size of the tip 14 reduces as the tip 14 tapers down to a lowest point at 20. The tip 14 may be formed integrally with the pile 12 or may be connected to it, for instance by 3 means of a spigot and socket arrangement illustrated schematically at 22. The pile 12 may be in sections, connected end to end by similar spigot and socket arrangements, but the pile 12 is illustrated in Fig. 2 as a single length, for simplicity.

The tip 14 is preferably formed of the same material as the pile 12, and may incorporate reinforcement, as required. Although the illustrated tip 14 is tapered, which is particularly good for driving into sand, gravel and the like, the tip 14 could be of constant section, i.e. not tapered.

Fig. 2 shows the outlines of the pile 12 and tip 14, when viewed along the axis 24 of the pile 12. The outline 26 of the pile 12 has corners 28 at edges of the pile 12. The outline 30 of the tip 14 has corners 32 at the edges 34. However, as can be seen from Fig. 2, the outline 30 is out of register with the outline 26 in that the outline 30 has notionally turned relative to the outline 26.through about 45' as measured at the axis 24. The result is to leave four relatively small portions 36 of the tip 14 projecting beyond the outline 26, one in the region of each corner 32.

In the example shown, with both outlines 26,30 being square, it is appropriate for the outlines to be out of register by 45' (at the axis 24). For other polygonal outlines, this angle could be reduced, but is preferably about one half of the angle subtended at the axis 24 by the edges 34. Thus, for a hexagonal outline, the outlines would be out of register by about 9011.

The significance of this arrangement can be understood by considering the behaviour of the arrangement when driven. Initially, thetip 14 will penetrate the ground to form, in this example, a square hole of increasing size, as the tip 14 is driven more deeply. The pile 12 will then follow the tip 14 into the ground and will extend the hole to an eight pointed star shaped hole, having an outline complementary to the outermost outline of the shape shown in Fig. 2. Four of the points of this star shape will be occupied by corners 28; the other four points of the star will be occupied by corners 32. Consequently, strips 38 4 to either side of each corner 28 of the pile 12 will engage with the ground, but between these strips, there will be further strips 40 which are not in engagement with the ground, because a corner 28 will have formed an additional point in the star shape, thus spacing the strip 40 from the ground 16.

The result is that some engagement is provided between the pile 12 and the ground 16 and along the length of the pile 12. This assists stability and helps to guide the pile 12 as it is driven. However, skin friction between the pile 12 and the ground 16 is reduced because the strips 40 are not in contact with the ground.

The degree by which the skin friction is reduced will depend on the relative sizes of the outlines 26,30. If the outline 30 of the tip 14 is increased, the outline 30 will project further beyond the outline 26, and the strips 40 will become wider, thus further reducing skin friction. If, the outline 30 increased sufficiently to reach the corners 28, skin friction between the ground and the pile 12 would be removed entirely, but it is believed that some engagement between the pile 12 and the ground 16 is desirable to stabilise the pile along its length.

By reducing skin friction in this way, the noise and disturbance associated with piling is expected to be reduced. Furthermore, a greater part of the work applied to the pile 12 will be transferred to the tip, with less being lost in skin friction, thus making the operation more efficient.

In an alternative, the tip 14 could extend beyond the outline 30 by providing the tip 14 with circumferential, spiral or other ribs.

Many variations and modifications can be made to the apparatus described above, without departing from the scope of the present invention. In particular, materials, sizes, relative dimensions, driving techniques and the like can all be varied. In one example, the outline 26 has a side length of approximately 25Omm, with the outline 30 having a side length of approximately 3 5 Omm at its widest (uppermost) point.

Whilst endeavouring in the foregoing specification to draw attention to those features of the invention believed to be of particular importance it should be understood that the Applicant claims protection in respect of any patentable feature or combination of features hereinbefore referred to and/or shown in the drawings whether or not particular emphasis has been placed thereon.

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Claims

1. A piling arrangement comprising a pile and a tip member at the lowermost end of the pile, the tip member having an outline, when viewed along the length of the pile, which extends beyond the outline of the pile over at least part of the periphery of the pile.

2. A piling arrangement as claimed in claim 1 wherein the pile and tip member are integral.

3. A piling arrangement as claimed in any one of the preceding claims wherein the pile and tip member have a polygonal outline, the outline of the tip member being out of register with the outline of the pile, so as to extend beyond the pile outline.

4. A piling arrangement as claimed in any one of the preceding claims wherein the pile and tip member have substantially the same outline.

5. A piling arrangement as claimed in any one of the preceding claims, the outline of the tip member being out of register by one half of the angle subtended at the centre of the pile by the edges of the pile member.

6. A piling arrangement as claimed in any one of the preceding claims, wherein the pile and tip member are substantially rectilinear in outline.

7. A piling arrangement as claimed in claim 6, wherein the pile and tip member are out of register by 450.

8. A piling arrangement as claimed in any one of the preceding claims, wherein the tip member and pile are square in section.

9. A piling arrangement as claimed in any one of the preceding claims, wherein the tip member is larger in section than the pile member.

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1 0. A piling arrangement as claimed in any one of the preceding claims, wherein the tip member tapers down from the portion at which the tip member meets the pile.

11. A piling arrangement as claimed in any one of the preceding claims, wherein the tip member comprises rib means which project beyond the outline of the pile member.

12. A piling arrangement as claimed in claim 11, wherein the rib means is circumferential.

13. A piling arrangement as claimed in claim 11, wherein the rib means is spiral.

14. A method of piling in which a pile is provided with a tip member at its lowermost end, the tip member having an outline, when viewed along the length of the pile, which extends beyond the outline of the pile over at least part of the periphery of the pile.

15. A piling arrangement substantially as claimed herein with reference to the accompanying drawings.

16. A method of piling substantially as claimed herein with reference to the accompanying drawings.

17. Any novel subject matter or combination including novel subject matter disclosed herein, whether or not within the scope of or relating to the same invention as any of the preceding claims.