GB2454798A

GB2454798A - Method of splicing pile cages, components therefor, and assembled pile cage

Info

Publication number: GB2454798A
Application number: GB0820873A
Authority: GB
Inventors: Stephen Render; David Palmer
Original assignee: Romtech Ltd
Current assignee: Romtech Ltd
Priority date: 2007-11-14
Filing date: 2008-11-14
Publication date: 2009-05-20
Anticipated expiration: 2028-11-14
Also published as: GB2454798B; GB0820873D0; GB0722413D0

Abstract

A method of splicing pile cages, a set of components therefore, an assembled pile cage, a method of splicing together two pile cages of a reinforced concrete pile. The method comprises assembling first (10) and second (12) pile cages, providing the first pile cage with a stop member (56) adjacent to its top end, providing the second pile cage with an adjustment member (50) of a similar length to the second pile cage providing a suspension member (30) and a lifting member (40) upon the respective pile cages, lowering the first pile cage into a pile hole, supporting the first pile cage with its upper end at the top of the pile hole, lifting the second pile cage above the first pile cage and substantially coaxial therewith, 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, moving the lifting member to a position in which it can engage the suspension member, lifting the first and second pile cages together with the lifting member engaging the suspension member and preventing separation of the first and second pile cages, lowering the first and second pile cages together into the pile hole until the assembled pile cage engages the bottom of the pile hole, and the adjustment member engages the stop member, comparing the actual length of the second pile cage which projects from the pile hole with the desired projecting length, and adjusting the projecting length by way of the adjustment member as necessary.

Description

METHOD OF SPLICING PILE CAGES, COMPONENTS THEREFOR, AND ASSEMBLED PILE CAGE

FIELD OF THE INVENTION

This invention relates to a method of splicing pile cages, to the components therefor, and to an assembled pile cage, and in particular to a method of splicing together two pile cages of a reinforced concrete pile.

JO 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 first 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 above-ground structures such as 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 first or lower pile cage to the bottom end of a second or upper pile cage.

The pile cage is lowered into a pile 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 therefrom.

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 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.

DESCRIPTION OF THE PRIOR ART

International patent application WO2007/068898 which was published on 21 June 2007 describes a method of splicing pile cages and a set of components therefor.

Figs. 1 and 2 of that application are reproduced herein for ease of reference. As described more fully in the earlier application, the method employs two pile cages and 12 which are each assembled from a number of cage bars 14 and 16 respectively and at least one frame 20 (the frame of the first pile cage 10 terminates below the band 26 and is therefore not visible). The first pile cage 10 has a suspension band 30 adjacent to its upper end, the second pile cage 12 having at least one support plate 34 adjacent to its lower end, the support plate 34 having a hole 36 therethrough. The first pile cage 10 is lifted into a pile hole with its second end projecting therefrom, and the second pile cage 12 is lifted over the first pile cage and lowered 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 hole 36 in the support plate lies below the suspension band 30. A suspension bolt 40 is inserted through the hole in the support plate so that a part 42 of the suspension bolt lies underneath a part of the suspension band 30, enabling the first and second pile cages to be lifted together with the suspension bolt 40 engaging the suspension band 30.

Another embodiment of the invention is described, in which the support plate is elongated in the direction of the longitudinal axis of the pile cages, and specifically elongated so that it is substantially longer than the axial length of the suspension band. The support plate has two holes therethrough, each of which can receive a respective bolt. In use, it is arranged that the second pile cage is lowered to a relative position in which the support plate spans the suspension band, and the bolts are inserted into their respective holes with one of the bolts lying below the suspension band and the other bolt lying above the suspension band. The first pile cage can then be lifted together with the second pile cage with said one of the bolts engaging the bottom of the suspension band, and in addition the pile cages can be lowered to rest upon the bottom of the pile hole and the second pile cage can be supported by the first pile cage by virtue of said other bolt engaging the top of the suspension band.

This prior application addresses major concerns with splicing pile cages, namely the avoidance of the use of U-bolts or couplers, which have disadvantages in terms of health and safety, and cost, to the operator.

I

There is, however, another concern with splicing pile cages which is not addressed by this prior application, and that is the difficulty in ensuring that the top of the uppermost pile cage is correctly positioned relative to the top of the pile hole. The operator will seek to match the depth of the pile hole to the length of the pile cage, so that the depth of the pile matches the design specification, and also so that the length of the pile projecting above the pile hole matches that required for the connection of above-ground structures such as bridge supports and the like.

There are two major factors making the correct positioning of the pile cage more difficult. One is the likelihood of the cage bars sinking into the earth at the bottom of the pile hole, the other is rocks and other debris which may have been dislodged during drilling of the pile hole lying at the bottom of the hole and holding the pile cage above the bottom of the hole. The operator will usually fit the bottom of the cage bars of the lowermost pile cage with feet so as to reduce or avoid the cage bars sinking into the earth, but some sinkage will nevertheless occur in soft ground. There is little the operator can do to avoid the second factor.

Even reJatively small differences between the actual position of the pile cage and the intended position can have great effect at the top of the pile cage. For example, if the pile cage is to be connected to above-ground structures then the overlap between the top of the pile cage and the reinforcement of the above-ground structures is critical, and if the pile cage is only a few centimetres too low in the pile hole the overlap can be insufficient to meet the design requirements. In such an eventuality, the operator must extend the pile cage by fitting couplers to each of the cage bars, and then additional sections of cage bars to match the required overlap. Providing a coupler for each of the cage bars is very expensive, and before the couplers can be fitted the cage bars usually have to be cut down to provide an adequate length for the coupler and additional sections.

The delay in pouring the concrete into the pile hole can therefore be considerable, further adding to the cost of the piling contract, and it is known for the fitment of couplers to large pile cages to eliminate the profit in a piling contract.

The requirement to fit couplers as above described results from the pile cage dropping too far into the pile hole, for example because the cage bars of the lowermost pile cage sink into the earth at the bottom of the hole. If, on the other hand, the pile cage does not drop far enough, perhaps because of rocks or other debris in the bottom of the pile hole, then the cage bars can simply be cut down at the top of the pile hole to match the overlap required, so to that extent the problem is less significant. However, if the pile cage does not extend to the bottom of the pile hole then the pile may not meet its design criteria, and the operator may need to provide a longer pile cage, and a correspondingly deeper pile hole, to cater for such an eventuality.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a method of splicing, components for use in that method, and an assembled pile cage which address the above-stated concern, and seek to avoid or reduce the likelihood of the pile cage being incorrectly positioned in the pile hole.

According to the invention there is provided a method of adjusting the length of a spliced pile cage 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 a first end and a second end, {ii} assembling a second pile cage from a number of cage bars and at least one frame, the second pile cage having a first end and a second end, {iii} providing the first pile cage with a stop member adjacent to its second end, {iv} providing the second pile cage with an adjustment member, the adjustment member having a first end and a second end, the adjustment member being of a similar length to the second pile cage so that the first end of the adjustment member is located substantially at the first end of the second pile cage and the second end of the adjustment member is located substantially at the second end of the second pile cage, {v} providing a suspension member adjacent to the second end of the first pile cage or the first end of the second pile cage, {vi} providing at least one lifting member adjacent to the other of the second end of the first pile cage or the first end of the second pile cage, {vii} lowering the first pile cage into a pile hole with its second end uppermost, {viii} supporting the first pile cage with its second end at the top of the pile hole, {ix} lifting the second pile cage above the first pile cage and substantially coaxial therewith, with its first end lowermost, {x} 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, {xi} moving the lifting member to a position in which it can engage the suspension member, {xii} lifting the first and second pile cages together with the lifting member engaging the suspension member and preventing separation of the first and second pile cages, {xiii} lowering the first and second pile cages together into the pile hole until the assembled pile cage engages the bottom of the pile hole, and the first end of the adjustment member engages the stop member, {xiv} comparing the actual length of the second pile cage which projects from the pile hole with the desired projecting length, and {xv} adjusting the projecting length by way of the adjustment member as necessary.

Accordingly, the inventor has realised that it is not always possible to prevent the cage bars from sinking in to the earth at the bottom of the pile hole, and nor is it possible to prevent rocks or other debris stopping the pile cage from reaching the bottom of the pile hole, and so in order to achieve the correct positioning of the top of the pile cage the inventor adjusts the overlap between the respective ends of the first and second pile cages.

It is understood that there is a minimum required overlap between the pile cages in a spliced joint, and it can be ensured that the adjustment which is available cannot reduce the overlap below the minimum required.

Preferably, the adjustment member is a bolt or rod running substantially the full length of the second pile cage, the rod engaging a cooperating sleeve mounted upon the second pile cage, suitably mounted adjacent to the bottom end of the second pile cage. Desirably, the rod is threaded along at least part of its length, and the sleeve is correspondingly threaded so that rotation of the rod relative to the sleeve causes axial adjustment of the rod relative to the sleeve. When the end of the rod engages the end stop on the first pile cage, axial movement of the rod relative to the sleeve results in relative movement between the end stop and sleeve, and therefore in axial movement of the second pile cage relative to the first pile cage.

Because the rod extends to (or close to) the top of the second pile cage, the adjustment can be effected when the pile cage is resting on the bottom of the pile hole, i.e. the overlap of the spliced joint between the first and second pile cages can be adjusted, and hence the position of the top of the second pile cage relative to the top of the pile hole, can be adjusted, to cater for the actual sinkage or debris which has been encountered. In this way, the pile cage can be correctly positioned, quickly and easily, before the concrete is poured.

Desirably, the or each lifting member is a bolt movably mounted to a plate secured to one or more of the cage bars of the respective pile cage. Desirably also, the suspension member is a band secured to one or more of the cage bars of the respective pile cage. Ideally the band spans the circumference of the respective pile cage. As in W02007/068898 the suspension member can be mounted upon the second end of the first pile cage and the lifting member mounted upon the first end of the second pile cage, or vice versa.

It will be understood that some piles require three or more pile cages to be spliced together. In these cases a non-adjustable spliced joint according to W02007/068898 can be provided between the lowermost pile cages, with an adjustable spliced joint according to the present invention being provided between the top two pile cages (i.e. between the penultimate and final pile cages to enter the pile hole).

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described, by way of example, with reference to the accompanying drawings, in which: Fig.1 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 prior art; Fig.2 is a plan view of the first and second pile cages of Fig.1; and Fig.3 is a view of one of the cage bars of each of the first and second pile cages of an embodiment according to the present invention.

DETAILED DESCRIPTION

The present invention concerns a method of splicing together a first pile cage 10 and a second pile cage 12, as does the prior art method described in relation to Figs.1 and 2. 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 in this example is a helical wire wound around the outside of the cage bars 16, and secured to the cage bars at each junction therebetween, in known fashion.

The frame of the pile cage 10 may also be a helical wire similar to the helical wire 20, but in this example 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 always used, 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: assembling the first pile cage 10; lifting the first pile cage 10 until it is substantially coaxial with the pile hole and casing 22; lowering this pile cage into the casing 22; and 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 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.

A suspension band 30 is located between the trapping band 26 and the ends of the cage bars 14. In this example the suspension band 30 is a substantially circular strip of metal which lies inside the cage bars 14 and is welded to all of the cagebarsl4.

Fig.1 shows the optional feature of 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 of the trapping band 26 and suspension band 30. Accordingly, each of the cage bars 14 is forced to converge towards the longitudinal axis of the pile cage 10.

When the first pile cage 10 has been lowered into the position shown in Fig.1 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.1 until the respective cage bars 14,16 overlap.

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 minimum distance which depends upon several factors such as the diameter and length of the pile. The minimum overlap distance is determined in advance by the piling contractor or the pile cage manufacturer. During the splicing operation 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.

In the prior art method according to W02007/068898, adjacent to the lowermost end of the second pile cage 12 is located at least one support plate 34 (only one support plate 34 is shown in Fig.1 for simplicity but the preferred arrangement of three support plates is shown in Fig.2). The support plate 34 has a threaded hole 36 therethrough. The threaded hole 36 can receive the shank of a correspondingly threaded bolt 40 (Fig.2).

During the lowering of the second pile cage 12 from the position of Fig.1, 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 the threaded hole 36 lies below the suspension band 30, whereupon the bolt 40 can be inserted and tightened until its end 42 lies within the projected area of the suspension band 30.

When the bolt(s) 40 have been inserted sufficiently, and ideally tightened against their respective support plates 34, their respective ends 42 will lie within the projected area of the suspension band 30, as shown in Fig.2. The second pile cage can then be lifted slightly so as to move the bolts 40 into engagement with the underside of the suspension band, and further lifted so as to lift both the second pile cage 12 and the first pile cage 10 and 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. Because of their function in linking the two pile cages together during lifting, the bolts 40 are herein referred to as "lifting members".

In the embodiment shown the suspension band 30 is located upon the first pile cage 10 so that its lower edge is a distance Dl 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 minimum overlapping length of the cage bars 14 and 16 is the sum of Dl and D2, and it is arranged that this overlapping length matches (or exceeds) the minimum overlap distance required for the spliced joint.

An alternative arrangement in which the suspension band is mounted upon the second pile cage and the support plate is mounted upon the first pile cage is also described in W02007/068898.

The present invention shares the above-described components and method steps

of the prior art method and apparatus.

When the spliced pile cage of Fig.1 is lowered to the bottom of the pile hole the second pile cage 12 must be supported by the first pile cage 10. In this example the second pile cage 12 drops relative to the first pile cage until the end of the frame 20 engages the trapping band 26, so that the overlap distance when the concrete is poured is greater than Dl + D2. In an alternative example described in the prior art document the support plate 34 is extended and a further bolt is fitted therethrough to engage the top of the suspension band 30, whereby the second pile cage may be supported upon the suspension band 30.

The overlap distance between the first and second pile cages when the concrete is poured can therefore be controlled by the pile cage designer, so that the depth of the pile hole can be drilled to match the length of the spliced pile cage.

The present invention differs from the prior art method and apparatus in providing an adjustable overlap distance, so that the length of the assembled pile cage which projects from the pile hole can be adjusted to match the length required or desired for the connection to above-ground structures.

The apparatus according to the present invention is shown in Fig. 3, and includes an adjustment rod 50 which runs substantially the full length of the second pile cage 12 (i.e. the rod 50 is substantially the same length as each of the cage bars -12- 16). In this embodiment the adjustment rod is slightly longer than each of the cage bars 16 of the second pile cage, and projects slightly beyond both ends of the second pile cage 12, though this is not necessary. Thus, in alternative embodiments the first (lower) end of the adjustment rod terminates above the first end of one or more of the cage bars 16, and/or the second end of the adjustment rod terminates below the second end of one or more of the cage bars 16.

As is seen in Fig.3, in this embodiment the adjustment rod 50 lies inside the suspension band 30, so that in a plan view such as Fig.2 the adjustment rod would lie within the inner-most circle defined by the inside edge of the suspension band, perhaps alongside the part 42 of a suspension bolt 40. Alternatively, the adjustment rod could lie outside the suspension band, for example in the annular gap between the frame 20 and the suspension band 30, or less preferably it could lie outside the frame 20.

The top end of the adjustment rod 50 carries a hexagonal head 52 so as to receive a wrench or the like. The bottom end of the adjustment rod 50 is threaded and passes through a correspondingly-threaded adjustment sleeve 54 which is welded or otherwise secured adjacent to the bottom end of cage bar 16. The very bottom end of the adjustment rod 50 abuts an end stop 56 in the form of an anvil or the like which is welded or otherwise secured to a cage bar 14 of the first pile cage 10.

In the embodiment of Fig.3, the suspension bolt 40 is shown to be spaced from the bottom of the suspension band 30 by a separation distance S. The position shown in Fig.3 is the relative position of the first and second pile cages at the bottom of the pile hole, i.e. when the weight of the second pile cage 12 is supported upon the first pile cage 10. In the embodiments according to the invention, in this position the weight of the second pile cage 12 is supported upon the first pile cage 10 by way of the sleeve 54, the first end of the adjustment rod and the end stop 56. The overlap distance is Dl + D2 + S, and this represents the overlap distance when the concrete is poured. -13-

In Fig.3 the cage bar 16 (to which the sleeve 54 and support plate 34 are mounted) is shown in front of the cage bar 14 (to which the end stop 56 and the suspension band 30 are mounted), though these positions can be reversed. It is of course necessary that the end-stop 56 be positioned underneath the first end of the adjustment rod 50, and this can be achieved by making the end stop 56 annular or part-annular for example, or by controlling the relative positions of the cage bars 14 and 16 during the splicing operation so that alignment of the adjustment rod 50 and the end stop 56 is ensured.

It will be understood that when the second pile cage 12 is lowered into engagement with the first pile cage 10 as shown in Fig.1, the first end of the adjustment rod 50 can be guided into the end stop 56. However, when the spliced pile cage is subsequently lifted, the second pile cage 12 will lift relative to the first pile cage 10, i.e. the separation distance S will reduce to zero. The adjustment bolt 50 will therefore be lifted away from the end stop 56. The end stop 56 can incorporate a sleeve which is longer than the separation distance S, the first end of the adjustment rod being guided into the sleeve as the second pile cage 12 is lowered relative to the first pile cage. Because the sleeve is longer than the distance S the adjustment rod 50 will remain captive within the sleeve when the spliced pile cage is subsequently lifted.

The adjustment rod 50 may pass through additional guide sleeves mounted at spaced intervals along the length of the cage bar 16.

It will be understood that if the spliced pile cage projects too far from the pile hole when it has been lowered into position, the adjustment rod 50 may be rotated by way of the hexagonal head 52 so as to reduce the distance between the sleeve 54 and the end stop 56, effectively lowering the second pile cage 12 relative to the first pile cage 10. It will be understood that this increases the separation distance S between the bolt 40 and the suspension band 30 and increases the overlap distance. -14-

Alternatively, if the spliced pile cage does not project far enough from the pile hole, the adjustment rod 50 may be rotated so as to increase the distance between the sleeve 54 and the end stop 56, effectively raising the second pile cage 12 relative to the first pile cage 10. It will be understood that this reduces the separation distance S between the bolt 40 and the suspension band 30.

It is clearly advantageous that the second end of the adjustment rod 50 (and in particular the hexagonal head 52) lies above the cage bars 16 so that rotation of the adjustment rod 50 by a suitable wrench is substantially unhindered. It will be understood, however, that the invention could be utilised with a shorter adjustment rod, provided that the second end of the adjustment rod is accessible when the assembled pile cage engages the earth at the bottom of the pile hole.

The limits of adjustment are determined by the structure of the respective pile cages, i.e. the overlap distance can only be increased until the end stop 56 engages the sleeve 54, and can only be reduced until the suspension bolt 40 engages the suspension band 30. However, it is expected that only a few centimetres of adjustment will be required in the vast majority of applications, and the apparatus can be constructed to accommodate such range of adjustment.

It is preferred that the apparatus originally be configured to allow adjustment in both directions, i.e. to allow the necessary adjustment in the position of the second pile cage in the event of sinkage of the pile cage, or the encountering of rocks or other debris in the pile hole.

There are preferably two adjustment rods 50, at substantially diametrically opposed positions of the second pile cage 12, and in use both of the adjustment rods will be rotated together so as to avoid undue stress on the pile cages. The rods 50, sleeves 54 and end stops 56 must be sufficiently strong and secure to withstand the loads applied before the concrete has set.

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. The location of the various components will be chosen to suit the particular pile cages which are to be spliced.

As above stated, pile cages are spliced together if the depth of the pile is greater than the length of the individual pile cages which are available. In addition, however, another consideration is the height of the jib of the crane which is used to lift the pile cage into the pile hole. If the pile is required to be sunk to a depth of metres for example the crane jib will need to be at least 65 metres above the top of the pile hole if the pile is to have a single pile cage, and it will be understood that providing a crane with such a jib height is often inappropriate and/or uneconomic. Providing shorter-length pile cages and splicing the pile cages together as described above reduces the required height of the crane jib. -16-

Claims

1. A method of adjusting the length of a spliced pile cage 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 a first end and a second end, {ii} assembling a second pile cage from a number of cage bars and at least one frame, the second pile cage having a first end and a second end, {iii} providing the first pile cage with a stop member adjacent to its second end, {iv} providing the second pile cage with an adjustment member, the adjustment member having a first end and a second end, the adjustment member being of a similar length to the second pile cage so that the first end of the adjustment member is located substantially at the first end of the second pile cage and the second end of the adjustment member is located substantially at the second end of the second pile cage, {v} providing a suspension member adjacent to the second end of the first pile cage or the first end of the second pile cage, {vi} providing at least one lifting member adjacent to the other of the second end of the first pile cage or the first end of the second pile cage, {vii} lowering the first pile cage into a pile hole with its second end uppermost, {viii} supporting the first pile cage with its second end at the top of the pile hole, {ix} lifting the second pile cage above the first pile cage and substantially coaxial therewith, with its first end lowermost, {x} 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, -17- {xi} moving the lifting member to a position in which it can engage the suspension member, {xii} lifting the first and second pile cages together with the lifting member engaging the suspension member and preventing separation of the first and second pile cages, {xiii} lowering the first and second pile cages together into the pile hole until the assembled pile cage engages the bottom of the pile hole, and the first end of the adjustment member engages the stop member, {xiv} comparing the actual length of the second pile cage which projects from the pile hole with the desired projecting length, and {xv} adjusting the projecting length by way of the adjustment member as necessary.

2. A set of components for assembling into a spliced pile cage comprising: {i} a first pile cage comprising a number of cage bars and at least one frame, the first pile cage having a first end and a second end and a stop member adjacent to its first end, {ii} a second pile cage comprising a number of cage bars and at least one frame, the second pile cage having a first end and a second end, and an adjustment member, the adjustment member having a first end and a second end, the adjustment member being of a similar length to the second pile cage so that the first end of the adjustment member is located substantially at the first end of the second pile cage and the second end of the adjustment member is located substantially at the second end of the second pile cage, {iii} one of the first pile cage and the second pile cage having a suspension member located adjacent to the second end of the first pile cage or the first end of the second pile cage, {iv} the other of the first pile cage and the second pile cage having at least one lifting member located adjacent to the second end of the first pile cage or the first end of the second pile cage. -18-

3. A set of components according to Claim 2 in which the suspension member is located adjacent to the second end of the first pile cage, and the support member is located adjacent to the first end of the second pile cage.

4. A set of components according to Claim 2 or Claim 3 in which the suspension member is a circumferential band secured to all of the cage bars of the respective pile cage.

5. A set of components according to any of Claims 2-4 in which the adjustment member is a rod, the rod engaging a sleeve mounted adjacent to the first end of the second pile cage.

6. A set of components according to Claim 5 in which the rod is threaded along at least part of its length, and the sleeve is correspondingly threaded so that rotation of the rod relative to the sleeve causes axial adjustment of the rod relative to the sleeve.

7. A first pile cage for use in assembling a spliced pile cage, the first pile cage comprising a number of cage bars and at least one frame, the first pile cage having a first end and a second end, a stop member and a suspension member being located adjacent to its second end.

8. A second pile cage for use in assembling a spliced pile cage, the second pile cage comprising a number of cage bars and at least one frame, the second pile cage having a first end and a second end, and an adjustment member, the adjustment member having a first end and a second end, the adjustment member being of a similar length to the second pile cage so that the first end of the adjustment member is located substantially at the first end of the second pile cage and the second end of the adjustment member is located substantially at the second end of the second pile cage, and at least one lifting member located adjacent to its first end.

9. A first pile cage for use in assembling a spliced pile cage, the first pile cage comprising a number of cage bars and at least one frame, the first pile cage having a first end and a second end, a stop member adjacent and at least one lifting member located adjacent to its first end.

10. A second pile cage for use in assembling a spliced pile cage, the second pile cage comprising a number of cage bars and at least one frame, the second pile cage having a first end and a second end, and an adjustment member, the adjustment member having a first end and a second end, the adjustment member being of a similar length to the second pile cage so that the first end of the adjustment member is located substantially at the first end of the second pile cage and the second end of the adjustment member is located substantially at the second end of the second pile cage, and a suspension member located adjacent to its second end.

11. An assembled pile cage comprising a first pile cage and a second pile cage spliced together, the first pile cage comprising a number of cage bars and at least one frame, the first pile cage having a first end and a second end and a stop member adjacent to its first end, the second pile cage comprising a number of cage bars and at least one frame, the second pile cage having a first end and a second end, and an adjustment member, the adjustment member having a first end and a second end, the adjustment member being of a similar length to the second pile cage so that the first end of the adjustment member is located substantially at the first end of the second pile cage and the second end of the adjustment member is located substantially at the second end of the second pile cage, the first pile cage and the second pile cage being held together by way of a suspension member and a lifting member with a part of the cage bars of the first pile cage overlapping a part of the cage bars of the second pile cage, the adjustment member engaging the stop member and determining the length of the overlap.