GB2463946A

GB2463946A - Improvements in or relating to piles and pile joints

Info

Publication number: GB2463946A
Application number: GB0818205A
Authority: GB
Inventors: Roger Bullivant
Original assignee: ROXBURY PATENTS Ltd
Current assignee: ROXBURY PATENTS Ltd
Priority date: 2008-10-04
Filing date: 2008-10-04
Publication date: 2010-04-07
Also published as: GB0818205D0

Abstract

A pile joint to interconnect reinforcement elements 16 includes a male portion 20 insertable into a female portion 22, each portion having teeth 40 which mutually engage. The teeth are positioned such that when engaged they contact on one face, imparting a tension force; but there is clearance on the opposing face to allow the male member to move further into the female member and ensure there is no compressive force. There is preferably a lateral screw 78 to force the formations to engage. There may be a resilient gasket 28 between the bodies 24. Preferably the reinforcing members, and male portions are elongate and mutually parallel The direction of insertion is also preferably parallel while the teeth are preferably perpendicular. The reinforcement members are ideally for concrete bodies 24.

Description

Improvements in or Relating to Piles and Pile Joints The present invention relates to improvements in or relating to piles and pile joints.

Ground piles are commonly used beneath buildings and other structures, as part of their foundations. In one alternative, ground piles are installed by driving by hammer blows or vibration, This applies compressive shock forces to the top of the pile, causing the pile to be driven down into the ground. Long piles can conveniently be formed in sections, with additional sections being connected to the pile at surface level, as the pile is driven, until the pile has been driven to the required depth. Joints formed between the pile sections are therefore required to connect the pile sections without adversely affecting the performance of the pile either during driving or subsequent use.

Examples of the present invention provide a pile having a plurality of sections, there being at least one joint between adjacent sections and comprising: a male portion connected within a first of the adjacent sections to a reinforcing member; a female portion connected within a second of the adjacent sections to another reinforcing member and receiving the male portion to form a connection between the reinforcing members; the male and female portions having interlocking formations which engage, in use, to prevent withdrawal of the male portion from the female portion, to connect the reinforcing members when the joint is under tension; and the interlocking portions being so formed as to allow the male portion to penetrate more deeply into the female portion when the joint is under compression, to disconnect the reinforcing members when the joint is under compression.

The male and female portions may together define an entry direction for the male portion into the female portion, wherein the interlocking formations are formed to interlock by a relative movement of the male and female portions in an interlock direction, after the male portion has entered the female portion.

The reinforcing members may be elongate and generally aligned, the entry direction being generally parallel with the reinforcing members. The interlock direction may be generally perpendicular to the entry direction.

The interlocking formations may each comprise teeth defining gaps between them, the teeth of each portion being received in the gaps of the other portion when the formations are interlocked. The gaps may be wider than the teeth, along the entry direction. When the formations are interlocked, there may be engagement between those faces of the portions which face the reinforcing member to which that portion is attached, and clearance between those faces of the portions which face the reinforcing member to which the other portion is attached. The engaging faces of the portions may be angled relative to the interlock direction, to pull the male portion further into the female portion as the portions are interlocked.

Each pile section may have a body in which the reinforcing member is embedded, there being a resilient gasket between the bodies and which is compressed as the male portion is pulled further into the female portion. The bodies may be of a material liable to fracture under compressive shock. The bodies may be of cementitious material, such as concrete. n

The pile may further comprise a Jock arrangement operable to create the said relative movement to interlock the male and female portions. The Jock arrangement may comprise a threaded arrangement operable to create the said relative movement. The Jock arrangement may be accessible for operation from outside the pile, after the male portion has entered the female portion. The Jock arrangement may comprise a threaded member operable to tighten the interlocking portions together. The threaded member may be formed to break when tightened to a preset torque.

Examples of the present invention also provide a pile joint for a sectional pile, comprising: a male portion for connection within a first pile section to a reinforcing member; a female portion for connection within a second pile section to another reinforcing member and for receiving the male portion to form a connection between the reinforcing members; the male and female portions having interlocking formations which engage, in use, to prevent withdrawal of the male portion from the female portion, to connect the reinforcing members when the joint is under tension; and the interlocking portions being so formed as to allow the male portion to penetrate more deeply into the female portion when the joint is under compression, to disconnect the reinforcing members when the joint is under compression.

The interlock direction may be generally perpendicular to the entry direction.

The interlocking formations may each comprise teeth defining gaps between them, the teeth of each portion being received in the gaps of the other portion when the formations are interlocked. The gaps may be wider than the teeth, along the entry direction. When the formations are interlocked, there may be engagement between those faces of the portions which face the reinforcing member to which that portion is to be attached, and clearance between those faces of the portions which face the reinforcing member to which the other portion is to be attached. The engaging faces of the portions may be angled relative to the interlock direction, to pull the male portion further into the female portion as the portions are interlocked.

There may be a resilient gasket for location between, bodies in which the reinforcing members are embedded and which is compressed as the male portion is pulled further into the female portion.

The joint may further comprise a lock arrangement operable to create the said relative movement to interlock the male and female portions. The lock arrangement may comprise a threaded arrangement operable to create the said relative movement. The lock arrangement may comprise a threaded member operable to tighten the interlocking portions together. The threaded member may be formed to break when tightened to a preset torque.

In another example, the invention provides a pile section having a first end and a second end, the pile section having, at the first end, a male portion of a pile joint in accordance with the second aspect of the invention set out above, and the pile section having, at the second end, a female portion of a pile joint in accordance with the second aspect of the invention set out above.

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 highly schematic diagram of a sectional pile, during installation; Fig. 2 is an enlarged diagrammatic section of a joint for the pile of Fig. 1; Figs. 3 to 5 correspond with Fig. 2, showing stages of connection of the joint; Figs. 6a to 6c are enlarged details of the joint, during connection; and 1 5 Figs. 7 and 8 correspond with Figs. 3 and 5, showing an alternative joint.

Figure 1 Hlustrates a sectional pile 10 being driven into the ground 12 by driving forces indicated by an arrow 14. The pile 10 consists of several sections lOa, each consisting of a body of cementitious material, such as concrete, in which reinforcing structures 16 are embedded. Each pile section lOa is joined at its upper and lower ends to another pile section lOa, by an appropriate joint, the details of which are to be described.

As the driving forces 14 drive the pile 10 further down into the ground 12, additional sections iDa can be attached to the top of the pile 10 until the pile 10 has been driven to the desired depth.

Figure 2 illustrates in more detail a joint 18 for use between adjacent sections of the pile 10. The joint 18 has a male portion 20, generally toward the top of the drawing, in this orientation, and a female portion 22 generally toward the bottom of the drawing, in this orientation.

Each of the pile sections lOa has a body 24 of precast concrete reinforced by the reinforcing structures 16, in the form of bars 16 which extend through the body 24, parallel with the axis 42 of the pile 10. The end faces 26 of the bodies 24 are adjacent, but are separated by a gasket 28 of compressible material, such as felt.

The male portion 20 has a base 30 connected, such as by welding, to the reinforcing bar 16 within the section lOa. A finger 32 extends from the base 30 beyond the end face 26. The female portion 22 similarly has a base 34 connected, such as by welding, to the corresponding reinforcing bar 16 within the section Wa. The base 34 carries a cup 36 which has a mouth at the end face of the section lOa and contains a finger 38, which does not project beyond the end face of the pile section lOa. The dimensions of the cup 36 and the finger 38 allow the finger 32 of the male portion 20 to be received within the cup 36, alongside the finger 38.

The fingers 32, 38 have interlocking formations 40 which engage, in use, to prevent withdrawal of the finger 32 from the cup 36.. This results in the reinforcing bars 16 being connected through the fingers 32, 38, when the joint 18 is under tension. However, as will be described, the interlocking formations are formed to allow the finger 32 of the male portion 20 to penetrate more deeply into the cup 36 of the female portion 22 when the joint 18 is under compression, to disconnect the reinforcing bars 16, when the joint is under compression.

In this example, the bars 16 lie on the axis 42 of the pile 10, and the fingers 32, 38 each extend alongside the axis 42. The cup 36 defines a space 44 alongside the finger 38. Accordingly, the male and female portions 20, 22 together define an entry direction for the male portion into the female portion, which is generally parallel with the axis 42, allowing the male finger 32 to enter the space 44 alongside the female finger 38. Accordingly, as can be seen from figure 2, the reinforcing bars 16 are elongate and generally aligned in the finished joint 18, the entry. direction being generally parallel with the piJe axis 42 and thus with the bars 16.

The finger 32 carries teeth 46 which define gaps 48 between them. Similarly, the finger 38 carries teeth 50 which define gaps 52 between them. The dimensions of the teeth 46, 50 and gaps 48, 52 allow the fingers 32, 38 to be interlocked by bringing the fingers 32, 38 together so that the teeth 46, 50 of each portion 20, 22 are received in the gaps 52, 48 of the other portion 22, 20 when the teeth are interlocked. This interlocking is achieved by relative movement of the male and female portions 20, 22 in an interlock direction after the male finger 32 has entered the cup 36. In this example, the interlock direction is generally perpendicular to the entry direction. That is, after initially introducing the male finger 32 into the cup 36 by relative movement generally parallel with the pile axis 42, the two pile sections lOa are then moved generally transverse to the axis 42, IS relative to each other, in order to mesh the fingers 32, 38 together, introducing the teeth 46, 50 into the gaps 52, 48, respectively.

Figure 2 illustrates the situation after the teeth 46, 50 have fully meshed. A lock arrangement indicated generally at 54 is provided to create the transverse interlocking movement just described, and to hold the fingers 32, 38 in their interlocked condition thereafter. The lock arrangement 54 comprises a threaded member 56 in the form of a bolt received in a threaded socket 58. Rotation of the bolt 56 advances the tip 60 of the bolt 56 to bear against the finger 32 to push the finger 32 toward the finger 38 until the teeth 46, 50 have meshed, and thereafter to prevent the fingers 32, 38 moving apart to free the teeth 46, 50.

The sequence of events used to make the joint 18 are illustrated in Figures 3, 4 and 5. In the initial condition (Figure 3), the male finger 32 is initially offered to the cup 36 to enter the space 44 alongside the female finger 38. It is to be noted that in this initial condition, the upper pile section lOa is slightly offset relative to the lower pile section. That is, the reinforcing bar 16 of the upper section lOa is

S

slightly offset from the axis of the reinforcing bar 16 of the lower section 10a, which is in turn the pile axis 42. This provides clearance between the teeth 46, 50, allowing the finger 32 to enter the cup 36.

It is also to be noted that, in Figure 3, the bolt 56 is in a withdrawn position so that the tip 60 does not interfere with the finger 32, as it enters the cup 36. The head 61 of the bolt 56 is outside the pile 10.

As the pile sections iDa are brought together, the condition of Figure 4 is reached, in which the finger 32 has fully entered the cup 36. The misalignment of the bars 16 can clearly be seen in Figure 4, at steps 62. The head 61 of the bolt 56 can now be used to turn the bolt 56 in order to advance the tip 60 and push the finger 32 across the cup 36 (generally perpendicular to the pile axis 42), until the teeth 46, 50 mesh. This action is indicated by the circular arrows 64. In addition to meshing the teeth 32, 38, this movement in the interlock direction also brings the bars 16 into alignment at the pile axis 42. In one example, the bolt 56 is locally weakened, such as by a circumferential slot, so that the head 61 breaks off when the bolt 56 has been tightened against the finger 32 to a preset torque value. This is indicated in the inset to Figure 5, showing the head 61 broken from the bolt 56.

Further details of the teeth 46, 50 and the interlocking action between the fingers 32, 38 can now be described in more detail, with particular reference to Figures 6a, 6b, and 6c.

Figure 6a represents the condition after the finger 32 has been introduced into the cup 36 and has just begun to move in the interlock direction. In this condition, the weight of the upper section iDa is resting on the lower section lOa, with the gasket 26 between them. The weight of the upper section lOa will cause some compression of the gasket 26.

It can be seen from these drawings that the gaps 48, 52 are wider along the entry direction (along the pile axis 42) than the teeth 46, 50. The upper faces 66 of the teeth 46 move into engagement with the lower faces 68 of the teeth 50. That is, there is engagement between those faces 66, 68 of the fingers 32, 38 which face the reinforcing bar 16 to which the respective finger 32, 38 is attached. There is clearance between the lower faces 70 of the teeth 46 and the upper faces 72 of the teeth 50. That is, there is clearance between those faces 70, 72 which face the reinforcing bar 16 to which the other finger 32, 38 is attached.

The faces which engage (that is, the faces 66, 68) are.angled relative to the interlock direction, This causes a wedge action as the fingers 32, 38 are pushed together by the bolt 56, forcing the male finger 32 to be pulled further into the cup 36. The force on the teeth 46, arising from the wedge action, is illustrated in Figure 6b and 6c by arrows 74. This force 74 causes the gasket 28 to be further compressed as the fingers 32, 38 mesh together. The dimensions of the teeth 46, 50 and of the gasket 28 may be chosen so that once the teeth 46, 50 have been fully meshed, the gasket 28 is substantially fully comi3ressed.

Once the teeth 46, 50 are fully meshed, the compression and resilience of the gasket 28 holds the faces 66, 68 in engagement, and maintains a separation 76 between the faces 70, 72. This engagement and separation can be seen in Figure 2, and particularly in Figure 6c. This engagement and separation has significance while the pile is being installed, and during use..

While the pile is being installed, hammer blows or other driving forces are applied to the pile 10, as has been described. This results in compressive shock propagating down the pile 10. When these shock forces encounter a joint 18, the forces cannot be transmitted directly from one reinforcing bar 16 to the other, across the joint 18. This is because the compressive nature of the shock forces will tend to drive the male finger 32 further into the cup 36,which it is initially free to do without the teeth 46 engaging the next tooth 50 below (which would be by l0 engagement of the faces 70, 72), by virtue of the separation 76. Accordingly, the compressive shock forces are transmitted through the end faces 26, by means of the gasket 28. This results in the shock forces being distributed across substantially the whole of each end face 26, reducing the likelihood of localised fracture or other damage of the concrete or other fragile material of the bodies During use of the pile 10, tension forces in the pile 10 can be transmitted directly between the reinforcing bars 16, across the joint 18, by virtue of the engagement of the faces 66, 68.

In each case, the interlocking of the fingers 32, 38 prevents withdrawal of the male portion 20 from the female portion 22 and thereby connects the reinforcing bars 16 when the joint 18 is under tension, but the interlocking formations allow the male portion 20 to penetrate more deeply into the female portion 22 when the joint 18 is under compression, thereby disconnecting the reinforcing bars 16 when the joint 18 is under compression. The result is a pile joint which is expected to provide advantageous properties during installation, such as reduced risk of damage to the pile sections, and advantageous properties during use, such as improved performance under tension.

Figures 7 and 8 illustrate another example embodiment of the invention. This example has many close similarities with the example described above and consequently, the same reference numerals are used in relation to corresponding features. The principal difference between the two examples relates to the form of the fingers 32, 38. In the first example, described abo.ve, the fingers 32, 38 taper. That is, the crowns of the teeth 46, 50 are aligned at an angle to the pile axis 42. Accordingly, the entry clearance between the teeth 46, 50 is also at an angle to the pile axis 42. In the alternative example of Figures 7 and 8, the crowns of the teeth 46, 50 are aligned parallel with the pile axis 42. Accordingly, the entry clearance between the teeth 46, 50 is also parallel vvith the pile axis 42. I!

It is envisaged that in practice, one or other of these arrangements may prove more convenient, in various circumstances.

Figures 7 and 8 also show the threaded bolt 56 replaced by a short set screw 78 S which has a socket 80 accessible for an appropriate tool, through the socket 58, to push the finger 32 toward the finger 38 in the manner described above.

Many variations and modifications can be made to the apparatus described above, without departing from the scope of the present invention.

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 13 drawings whether or not particular emphasis has been placed thereon.

Claims

CLAIMS1. A pile having a plurality of sections, there being at least one joint between adjacent sections and comprising: a male portion connected within a first of the adjacent sections to a reinforcing member; a female portion connected within a second of the adjacent sections to another reinforcing member and receiving the male portion to form a connection between the reinforcing members; the male and female portions having interlocking formations which engage, in use, to prevent withdrawal of the male portion from the female portion, to connect the reinforcing members when the joint is under tension; and the interlocking portions being so formed as to allow the male portion IS to penetrate more deeply into the female portion when the joint is under compression, to disconnect the reinforcing members when the joint is under compression.
2. A pile according to claim 1, wherein the male and female portions together define an entry direction for the male portion into the female portion, wherein the interlocking formations are formed to interlock by a relative movement of the male and female portions in an interlock direction, afterihe male portion has entered the female portion.
3. A pile according to claim 2, wherein the reinforcing members are elongate and generally aligned, the entry direction being generally parallel with the reinforcing members.
4. A pile according to claim 2 or 3, wherein the interlock direction is generally perpendicular to the entry direction.
5. A pile according to any preceding claim, wherein the interlocking formations each comprise teeth defining gaps between them, the teeth of each portion being received in the gaps of the other portion when the formations are interlocked.
6. A pile according to claim 5, wherein the gaps are wider than the teeth, along the entry direction.
7. A pile according to any preceding claim, wherein, when the formations are interlocked, there is engagement between those faces of the portions which face the reinforcing member to which that portion is attached, and clearance between those faces of the portions which face the reinforcing member to which the other portion is attached.
8. A pile according to any preceding claim, wherein the engaging faces of the portions are angled relative to the interlock direction, to pull the male portion further into the female portion as the portions are interlocked.
9. A pile according to any preceding claim, wherein each pile section has a body in which the reinforcing member is embedded, there being a resilient gasket between the bodies and which is compressed as the male portion is pulled further into the female portion.
10. A pile according to claim 9, wherein the bodies are of a material liable to fracture under compressive shock.
11. A pile according to claim 9 or 10, wherein the bodies are of cementitious material, such as concrete.
12. A pile according to any preceding claim, wherein the pile further comprises a lock arrangement operable to create the said relative movement to interlock the male and female portions.
13. A pile according to claim 12, wherein the lock arrangement comprises a threaded arrangement operable to create the said relative movement.
14. A pile according to claim 12 or 13, wherein the lock arrangement is accessible for operation from outside the pile, after the male portion has entered the female portion.
15. A pile according to any of claims 12 to 14, wherein the lock arrangement comprises a threaded member operable to tighten the interlocking portions together.
16. A pile according to claim 15, wherein the threaded member is formed to break when tightened to a preset torque.
17. A pile joint for a sectional pile, comprising: a male portion for connection within a first pile section to a reinforcing ni ember; a female portion for connection within a second pile section to another reinforcing member and for receiving the male portion to form a connection between the reinforcing members; the male and female portions having interlocking formations which engage, in use, to prevent withdrawal of the male portion from the female portion, to connect the reinforcing members when the joint is under tension; and the interlocking portions being so formed as to allow the male portion to penetrate more deeply into the female portion when the joint is under compression, to disconnect the reinforcing members when the joint is under compression.
18. A pile joint according to claim 17, wherein the male and female portions together define an entry direction for the male portion into the female portion, wherein the interlocking formations are formed to interlock by a relative movement of the male and female portions in an interlock direction, after the male portion has entered the female portion.
19. A pile joint according to claim 18, wherein the interlock direction is generally perpendicular to the entry direction.
20. A pile joint according to any of claims 17 to 19, wherein the interlocking formations each comprise teeth defining gaps between them, the teeth of each portion being received in the gaps of the ther portion when the formations are interlocked.
21. A pile joint according to claim 20, wherein the gaps are wider than the teeth, along the entry direction.
22. A pile joint according to any of claims 17 to 21, wherein when the formations are interlocked, there is engagement between those faces of the portions which face the reinforcing member to which that portion is to be attached, and clearance between those faces of the portions which face the reinforcing member to which the other portion is to be attached.
23. A pile joint according to any of claims 17 to 22, wherein the engaging faces of the portions are angled relative to the interlock direction, to pull the male portion further into the female portion as the portions are interlocked.
24. A pile joint according to any of claims 17 to 23, wherein there is a resilient gasket for location between bodies in which the reinforcing members are embedded and which is compressed as the male portion is pulled further into the female portion.
25. A pile joint according to any of claims 17 to 24, wherein the joint further comprises a lock arrangement operable to create the said relative movement to interlock the male and female portions.
26. A pile joint according to claim 25, wherein the lock arrangement comprises a threaded arrangement operable to create the said relative movement.
27. A pile joint according to claim 25 or 26, wherein the lock arrangement comprises a threaded member operable to tighten the interlocking portions together.
28. A pile joint according to claim 27, wherein the threaded member is formed to break when tightened to a preset torque.
29. A pile section having a first end and a second end, the pile section having, at the first end, a male portion of a pile joint according to any of claims 17 to 28,, and the pile section having, at the second end, a female portion of a pile joint according to any of claims 17 to 28.
30. A pile substantially as described above, with reference to the accompanying drawings.
31. A pile joint substantially as described above, with reference to the accompanying drawings.
32. A pile section substantially as described above, with reference to the accompanying drawings.
33. 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.