IE86572B1 - Method of splicing pile cages, set of components therefore, and assembled pile cages - Google Patents

Abstract

This invention relates to a method of splicing pile cages, to a set of components therefore, and to assembled pile cages, and in particular to a method of splicing together two pile cages of a reinforced concrete pile. It is an object of the present invention to provide a method of splicing, and a set of components for use in that method, which avoids or reduces the disadvantages of the known methods. In particular the inclusion of blind bolts and support plates provide a safe and cost effective way of splicing together two pile cages. When the pile cages are correctly positioned the blind bolts can be tightened so as to project through the holes and into alignment with the support plates by use of a screwdriver and suitable wrench. By using a screw driver and wrench the operator can keep his or her hands well away from the pile cages, which will significantly reduce the likelihood of injury in the event of inadvertent movement of one or both of the pile cages. <Figure 1>

Description

Method of splicing pile cages, set of components therefore, and assembled pile cages Field of invention This invention relates to a method of splicing pile cages, to a set of components therefore, and to assembled pile cages, and in particular to a method of splicing together two pile cages of a reinforced concrete pile.

In the following description, directional and orientational terms such as top, upper etc. refer to the normal orientation of use, as represented in Fig. 1. Also, the terms “first” and “second” when used in relation to the pile cages, and in relation to the respective ends of the pile cages, refer to the order in which the parts enter the pile hole, i.e. the first end of the pile cage is the lower end and enters the pile hole before the second or upper end.

Background to the invention Reinforced concrete piles are known for use in the foundations of roadway bridges and the like. The piles are sunk deep into the ground and can for example provide a link between the bridge supports and the underlying rocks. The pile comprises a metallic pile cage embedded in concrete, the pile cage acting both as a reinforcement for the concrete and also as a means to tie the bridge support or the like to the pile. The pile cage comprises a number of cage bars which in use are arranged to lie substantially along the longitudinal axis of the pile. These bars are interconnected by one or more frames which maintain the separation and alignment of the cage bars, and in many designs of pile cage the frame comprises a helical wire which surrounds and interconnects the cage bars.

Often the cage is assembled off-site at a dedicated manufacturing plant, and is delivered to the site for insertion into the hole created for the pile.

If the depth of the pile is greater than the length of the available pile cages, then the piling contractor will have to splice together two or more pile cages, i.e. connect the top end of a lower pile cage to the bottom end of an upper pile cage.

The pile cage is lowered into a hole which has been drilled into the ground by a drill or augur. The pile cage can be pressed down into wet concrete, the concrete being pumped into the hole as the augur is removed there from. Alternatively, a casing is inserted into the hole and the pile cage is inserted into the casing, the concrete then being poured around the pile cage and the casing -286572 subsequently being removed (so that it can be reused). A casing will typically be used when the pile cages are required to be spliced.

When two pile cages are to be spliced together, the helical wire of one or both of the pile cages will typically be terminated away from the end of the cage bars, so that the cage bars project beyond the helical wire and allow an overlap to be created between the cage bars of the respective pile cages, the length of overlap required being determined in advance by the piling contractor.

Statement of invention It is an object of the present invention to provide a method of splicing, and a set of components 10 for use in that method, which avoids or reduces the disadvantages of the known methods.

According to the invention there is provided a method of splicing comprising the steps of: {i} assembling a first pile cage from a number of cage bars and at least one frame, the first pile cage having at least two support plates adjacent to one of its ends, the support plates having two holes there through {ii} assembling a second pile cage from a number of cage bars and at least one frame, the second pile cage having at least two support plates adjacent to one of its ends, the support plates having two holes there through {iii} lifting the first pile cage and lowering this pile cage into a pile hole with its end having the suspension plates uppermost, {iv} supporting the first pile cage with its uppermost end projecting from the pile hole and with the suspension plates accessible, {v} lifting the second pile cage above the first pile cage and substantially coaxial therewith, with the end having the support plates lowermost, {vi} lowering the second pile cage relative to the first pile cage until a part of the cage bars of the second pile cage overlap a part of the cage bars of the first pile cage, and the holes in the support plates of the first cage lies equal to the holes of the support plate in the second cage, {vii} inserting two blind bolts through the holes in the support plates and fixing them with an Ml6mm nut, whereby the first and second pile cages can be lifted and lowered together with the blind bolts engaging both support plates and preventing separation of the first and second pile cages.

Accordingly, the provision of a support plate on the first (lowermost) pile cage and a support plate on the second (uppermost) pile cage enables a quick and easy method of securing the two pile cages together by way of inserting the blind bolts when there is a sufficient overlap between the respective ends of the pile cages. -3When the pile cages are correctly positioned the blind bolts can be tightened so as to project through the holes and into alignment with the support plates by use of a screwdriver and suitable wrench. By using a screw driver and wrench the operator can keep his or her hands well away from the pile cages, which will significantly reduce the likelihood of injury in the event of inadvertent movement of one or both of the pile cages.

The use of two blind bolts has been tested and can support the weight of 1.92 tonnes. This figure takes into account a factor of safety of 2.5. However, it is preferred that as a minimum four blind bolts are used. It may be preferred as a precaution that each pair of blind bolts can support the weight of the lower cage(s), and this additional security can easily be achieved (at relatively low cost) by using appropriate blind bolts and related components.

Desirably, the support plate is located around the inside of the cage bars of the first pile cage. Locating the support plate around the inside of the cage bars reduces the likelihood that the support plate will foul the cage bars or frame of the second pile cage.

Preferably, the support plate is located outside the cage bars in the second pile cage.

Each support plate is preferably welded or otherwise secured to a single cage bar of the both pile cages. Alternatively, (and provided it will not foul the cage bars ofthe other pile cage) the support plate can be a loop or part-loop spanning all or a large part of the periphery of the pile cages. When two support plates are used they are preferably diametrically opposed around the second pile cage, and if three plates are used they are preferably separated by approximately 120° around the second pile cage. It will be understood that with only one or two plates the first pile cage could pivot relative to the second pile cage, but such pivoting will in any event be limited by the pile hole or casing and may be acceptable in certain applications..

The arrangement of the support plates can of course be reversed within the scope of the present invention, with the support plate mounted adjacent to the uppermost end of the lowermost pile cage and the support plate mounted adjacent to the lowermost end of the uppermost pile cage, in which case the uppermost pile cage will be lowered until the support plate lies equally with the holes in the support plate prior to insertion of the blind bolts.

There is also provided a set of components for use in a method for splicing together two pile cages, the set of components comprising: {i} two support plates for fitment to a first pile cage, each support plate having two holes there through, {ii} two support plates for fitment to a second pile cage, each support plate having two holes there through, and {iii} a two blind bolts for each -4of the support plates, the blind bolt being sized for insertion into and through the hole in the support plate.

Furthermore, there is provided a first pile cage assembled from a number of cage bars and at least one frame, the pile cage having two support plates secured to the cage bars adjacent to an end of the cage bars, the support plates having two holes there through for receiving two blind bolts., and a second pile cage assembled from a number of cage bars and at least one frame, the pile cage having two support plates secured to a cage bar adjacent to an end of the cage bar, the support plates having two holes there through for receiving two blind bolts.

Brief description of the drawings The invention will be described, by way of example, with reference to the accompanying drawings, in which: Fig.l is a side view of part of the first pile cage and part of the second pile cage during the performance of the method according to the present invention; and Fig.2 is a plan view of alternative embodiments of first and second pile cages during a later stage 15 of the method.

Detailed description The present invention concerns a method of splicing together a first pile cage 10 and a second pile cage 12. In known fashion, the first pile cage 10 comprises a number of (in this embodiment six) cage bars 14 and at least one frame (not seen). The second pile cage similarly comprises a number of (in this embodiment also six) cage bars 16 and a frame 20. The frame 20 is a helical wire wound around the outside of the cage bars 16, and secured to the cage bars at each junction there between, in usual fashion.

It will be understood that the helical wire 20 is but one example of frame, and other frames may alternatively (or additionally) be used. The form of the frame or frames of each pile cage is not - relevant to the present invention.

The helical wire 20 continues almost to the (lowermost) ends of the cage bars 16 of the second pile cage 12, but in other embodiments the helical wire can terminate at, or further away from, the ends of the cage bars, as desired. - 5 The frame of the pile cage 10 may also be a helical wire similar to the helical wire 20, but in this embodiment the frame of the first pile cage 10 terminates a substantial distance away from the (uppermost) ends of the cage bars 14, so that the frame is hidden from view in this figure within the casing 22.

It will be understood that a casing is not essential to the present invention, but it is recognised that a casing will often be used when it is desired to splice pile cages together.

In common with prior art methods, the method according to the present invention comprises {i} assembling the first pile cage 10, {ii} lifting the first pile cage 10 until it is substantially coaxial with the casing 22, {iii} lowering this pile cage into the casing 22, and {iv} supporting the first pile cage 10 with its uppermost end projecting from the casing 22 as shown in Fig.1. Also in common with prior art methods, the first pile cage 10 in this embodiment is supported upon the casing by way of a trapping bar 24 which is laid across the top of the casing 22 and underneath a trapping band 26 which is secured to the cage bars 14.

The trapping band 26 may be secured to the cage bars 14 in a desired position solely for the purpose of suspending it from the casing 22 and allowing the desired length of cage bars 14 to project from the casing 22, or it may additionally be configured to provide a frame for the pile cage 10 and/or one or more lifting points for the pile cage.

In the present invention two support plates 30 are located between the trapping band 26 and the ends of the cage bars 14. In this embodiment the support plates 30 are a strip of metal which lies inside the cage bars 14 and is welded to both sides of the relevant cage bars 14. In alternative embodiments the support plate may be secured by means other than welding, and/or it may be secured to only some of the cage bars 14, but since the pile cage 10 will typically be assembled at a dedicated manufacturing facility, welding the support plates to the relevant cage bars 14 is possible and preferred.

Fig. 1 shows a preferred feature of the invention, namely the tapering of the upper end of the first pile cage 10. The tapering is achieved by securing each of the cage bars to an end band 32 which is substantially circular and has a diameter less than the diameter ofthe trapping band 26. Accordingly, each of the cage bars 14 is forced to converge towards the longitudinal axis of the pile cage 10.

The tapered form of the pile cage 10 is not essential for the performance of the present invention, but is preferred because it facilitates the alignment of the second pile cage 12 with the first pile -6cage 10, and reduces the accuracy required of the crane operator, and can therefore reduce the time taken by the splicing operation.

When the first pile cage 10 has been lowered into the position shown in Fig.l the second pile cage 12 can be lifted into position above the first pile cage 10 and substantially coaxial therewith, as is also shown in Fig. 1. The second pile cage 12 is then lowered from the position shown in Fig.l until the respective cage bars 14, 16 overlap.

As above indicated, the spliced joint between the pile cages 10 and 12 is not required to transmit the tensile stress from the cage bars 14 to the cage bars 16 (and vice versa), and instead that stress is transmitted by way of the concrete which is subsequently set around the spliced joint. To allow the concrete to transmit the stress the cage bars 14 are required to overlap the cage bars 16 by a distance which depends upon several factors such as the diameter and length of the pile, the overlap distance will be determined in advance by the piling contractor or the pile cage manufacturer. It is desirable that the first pile cage 10 project above the casing 22 by a distance which is greater than the required overlap, so that the second pile cage 12 can lie totally above the casing 22 as the spliced joint is being formed, and there is no likelihood of any of the second pile cage 12 fouling the trapping bar 24.

According to the invention, adjacent to the lowermost end of the second pile cage 12 is located at least two support plates 34 (only one support plate 34 is shown in Fig.l for simplicity but the preferred arrangement of two support plates is shown in the embodiment of Fig.2). The support plate 34 has two holes 36 there through. The holes 36 can receive the shank of a correspondingly blind bolt 40 (Fig.2), the bolt not being shown in Fig.l, During the lowering of the second pile cage 12 from the position of Fig.l, the cage bars 16 first pass around the end band 32 and the converging parts of the cage bars 14 and then between the cage bars 14 as they reach the end of the converging section, the helical wire 20 of the second pile cage 12 also surrounding the cage bars 14 of the first pile cage 10. The second pile cage 12 is lowered until both holes 36 in the support plate 34 lie equal to the holes 36 in the support plate 30, whereupon the blind bolt 40 can be inserted, then rotated through 180° to release the locking anchor 44 and the nut 42 tightened to the support plate 34.

It will preferably be arranged that the nut 42 must be fully tightened against the support plate 34, i.e. the nut 42 is rotated until its head engages the support plate 34 and can be tightened there against. The bolts 40 has a sufficiently long shaft to ensure that its end lies past the holes 36 in the support plate 30 as to allow the locking anchor to be released, as shown in Fig.2. This avoids -Ί any uncertainty for the operator in having to determine how far to insert the bolt, and ensures that the bolt can be made secure in its fully inserted position.

As above indicated, only one support plate 34 is shown in Fig.l, having two holes 36 for receiving two bolts 40, and whilst such an arrangement may be suitable for a small pile cage weighing perhaps 0,5 tonnes, it is generally preferred to use 2 support plates 34. When two support plates are used they are preferably diametrically opposed around the second pile cage 12, and if three plates are used they are preferably separated by approximately 120° around the second pile cage 12 as shown in Fig.2. It will be understood that with only one or two plates the first pile cage 10 could pivot relative to the second pile cage 12, but such pivoting will in any event be limited by the pile hole or casing and may be acceptable in certain applications.

When the bolts 40 have been inserted and tightened against their respective support plates 34 & 36, both the second pile cage 12 and the first pile cage 10 can be lifted to allow removal of the trapping bar 24. The pile cages 10 and 12 (which are now spliced together as required) can then be lowered together into the casing 22.

As seen in Fig.2, the blind bolts 40 are directed towards the centre of the pile cages 10 and 12. It is not necessary that they are aligned with the exact centre of the pile cages, but the more accurate their alignment the shorter will be the distance the bolts must span in order to lie equally with the holes 36 on the support plate 30.

In other embodiments, both support plates 34 & 30 can be extended in the longitudinal direction of the pile cage, and can be provided with two holes spaced in the longitudinal direction.

If desired or required, a third pile cage can be spliced to the upper end of the second pile cage 12, and so on, in similar fashion.

In the embodiment shown the support plate 30 is located upon the first pile cage 10 so that its lower edge is a distance DI from the ends of the cage bars 14 and the support plate 34 is located so that the top edge of the hole 36 is a distance D2 from the ends of the cage bars 16. When the pile cages 10 and 12 have been spliced together, the overlapping length of the cage bars 14 and 16 is the sum of DI and D2, and it is arranged that this overlapping length matches (or exceeds) the overlap distance required for the spliced joint, and in particular the overlap required for the concrete which is to be set around the spliced joint to transmit the tensile stress from the cage bars 14 to the cage bars 16 and vice versa. -8Also in the embodiment shown the number of cage bars in, and the diameters, of the pile cages 10 and 12 are the same, but this is not necessarily so, and in practice the number of cage bars and/or the diameters of the pile cages can differ. Clearly, the location of the suspension band and the support plate(s), and the length of the suspension bolts, will be chosen to suit the particular pile cages which are to be spliced.

Claims (8)

Claims

1. A method of splicing comprising the steps of: {i} assembling a first pile cage (10) from a number of cage bars (14) and at least one frame, the first pile cage having at least two support plates (30) adjacent to one of its ends, the support plates having two holes (36) there through {ii} assembling a second pile cage (12) from a number of cage bars (16) and at least one frame (20), the second pile cage having at least two support plates (34) adjacent to one of its ends, the support plates having two holes (36) there through {iii} lifting the first pile cage and lowering this pile cage into a pile hole with its end having the support plates (30) uppermost, {iv} supporting the first pile cage with its uppermost end projecting from the pile hole and with the support plates (30) accessible, {v} lifting the second pile cage above the first pile cage and substantially coaxial therewith, with the end having the support plates (34) lowermost, {vi} lowering the second pile cage relative to the first pile cage until a part of the cage bars of the second pile cage overlap a part of the cage bars of the first pile cage, and the holes in the support plates (30) lies equally to the holes in the support plates (34), {vii} inserting two blind bolts (40) through the holes in the support plates so that a part of the blind bolts lie through the holes in the support plate (30).

2. A method of splicing comprising the steps of: {i} assembling a first pile cage (10) from a number of cage bars (14) and at least one frame, the first pile cage having two support plates (34) adjacent to one of its ends, the support plates having two holes (36) there through {ii} assembling a second pile cage (12) from a number of cage bars (16) and at least one frame (20), the second pile cage having two support plates (30) adjacent to one of its ends, the support plates having two holes (36) there through {iii} lifting the first pile cage and lowering this pile cage into a pile hole with its end having the support plates (34) uppermost, {iv} supporting the first pile cage with its uppermost end projecting from the pile hole and with the support plates (34) accessible, {v} lifting the second pile cage above the first pile cage and substantially coaxial therewith, with the end having the support plates (30) lowermost, {vi} lowering the second pile cage relative to the first pile cage until a part of the cage bars of the second pile cage overlap a part of the cage bars of the first pile cage, and the holes in the support plates (34) lies equally to the holes in the support plates (30), {vii} inserting two blind bolts (40) through the holes in the support plates so that a part of the blind bolts lie through the holes in the support plate (34). -1010

3. A method according to Claim 1 or Claim 2 in which the cage bars of one of the first and second pile cages are caused to converge towards the centre of the pile cage at their ends, so that the pile cage tapers at one end.

4. A method according to Claim 1 or Claim 2 in which the support plates (30) are located inside or alongside the cage bars in the first pile cage (10).

5. A method according to Claim 1 or Claim 2 in which the support plates (34) are located outside or alongside the cage bars in the second pile cage (12).

6. A method according to Claim 1 or Claim 2 in which the support plates are bands spanning a part of the periphery of the pile cage.

7. A set of components for use in a method for splicing together two pile cages (10, 12), the set of components comprising: {i} two support plates (30) for fitment to a pile cage, {ii} two support plate (34) for fitment to the other pile cage, each support plate having two holes (36) there through, and {iii} two blind bolts (40) for each of the support plates, the blind bolts being sized for insertion into and through the holes (36) in the support plates

8. A first pile cage (10) assembled from a number of cage bars (14) and at least one frame, the pile cage having two support plates (30) secured to the cage bars adjacent to an end of the cage bars, and a second pile cage (12) assembled from a number of cage bars (16) and at least one frame (20), the second pile cage having two support plates (34) secured to a cage bar adjacent to an end of the cage bar, the support plates having two holes (36) there through for receiving two blind bolts (40).