IE980050A1

IE980050A1 - Improvements in or relating to apparatus for forming ground¹engaging supports

Info

Publication number: IE980050A1
Application number: IE980050A
Authority: IE
Inventors: Roger Alfred Bullivant
Original assignee: Roxbury Ltd
Priority date: 1997-01-29
Filing date: 1998-01-27
Publication date: 1998-07-29
Also published as: GB9801616D0; GB9701781D0; GB2322893B; GB2322893A

Abstract

A pile casing (10) for forming a pile by vibrating the casing into the ground is used to displace the earth to form a hole which can be subsequently filled by pile forming material as the casing is removed. The casing (10) has a plurality of longitudinally extending aperatures (20) which allow pile forming material into the casing (10). The material can leave the tip through hinged door members (30) to stay in the hole below the casing (10), once the casing is withdrawn. <Fig. 1>

Description

The present invention concerns improvements in or relating to apparatus for forming ground engaging supports, for example, piles or stone or soil 5 columns placed in the ground. $ * It is known to form piles in situ by driving a steel casing into the ground to be piled to a predetermined depth, the casing having a closed off end so that it displaces earth from the ground into which it has been driven to form a hole which can be filled with pile forming material, normally concrete but also particulate stone, or ameliorated soil, either with the casing remaining in place or with the casing removed and the concrete being poured into the hole left by the casing.

In the past this has been a relatively slow procedure and has suffered from the considerable disadvantage of earth and other debris falling into the | formed hole as the casing is being withdrawn.

Various proposals have been made to overcome this disadvantage, for | lexample, by pumping concrete to the casing tip as the casing is being removed £ (so that the retreating casing leaves behind it concrete which fills the hole as it is being exposed. In view of the limitations involved in concrete pumping this ^.2QA,| has not proved to be completely satisfactory, for example, only certain mixes of concrete can be poured and, furthermore, if the pile is to be formed by compacted particulate stone the process cannot be employed as this cannot be pumped.

According to a first aspect of the present invention there is provided a ipile forming apparatus comprising an elongate member adapted to receive ^nergy from a pile driving source at its upper end to drive it into the ground ’and having a pile tip at its leading end, the elongate member having a cross•feection which lies within the perimeter of the pile tip, and the tip including a ΓΕΝ TO PUBLIC INSPECTION member movable from a closed position when the elongate member is being driven to an open position when the member is being removed.

Preferably the elongate member includes three elongate components each having an arcuate cross-section arranged in back-to-back relationship with 5 the outer end regions of each component permanently lixed^o .the corresponding regions of its neighbours.

Alternatively, the elongate member includes a plurality of radially extending links.

Further alternatively, the elongate member is a hollow casing, which may 10 be of circular cross-section.

Preferably the movable member is hinged to the elongate member at its upper end and in its closed position is inclined relative to the longitudinal axis of the elongate member.

Preferably a plurality of hinged members are provided. There may be 15 three or four equlspaced, geometrically similar hinged members. Each hinged member, in its closed position, preferably abuts its neighbouring members such that the assembly of hinged members in the closed position forms a triangular or rectangular prism or cone.

Preferably the casing is apertured and the apertures in the casing have a 20 total surface area which is greater than the remaining casing surrounding the apertures. Preferably the apertures extend in the longitudinal direction of the casing, Preferably a stiffening member extends through the casing, having two, thr& or four limbs extending radially from the central axis of the casing to the inner casing wall.

Preferably the hinged members are mounted to a collar fixed to the leading end of the elongate member.

Preferably the casing has a circular or rectangular cross-section although octagonal, hexagonal cross-sections may be equally appropriate. ' * t * 5 Preferably means at the top of the elongate member is adapted to connect the elongate member to a vibrator to impart energy to the casing.

Preferably fins are provided on the leading end of the elongate member extending radially therefrom, each fin being located adjacent to the abutting edges of neighbouring hinged members. o Preferably the fins are retractable against the elongate member when the apparatus is being withdrawn from the pile hole.

Alternatively the fins are mounted to the apparatus by a removable member and remain down the pile hole when the elongate member is withdrawn.

Preferably the pile forming apparatus includes a hopper through which the elongate member extends such that fluent material, for example concrete or particulate stone in the hopper can flow down the hole made by the pile tip alongside the elongate member from the hopper subsequently to flow out of the leading end of the apparatus as it is withdrawn. A supply arrangement may be provided for the hopper, the supply arrangement comprising a material reservoir discharging into a feed channel which incorporates a screw feed arrangement which, on operation, transfers material from the supply reservoir to the hopper. t According to a further aspect of the present invention there is provided a method of forming a pile, comprising driving an elongate member having an openable member at its leading end into the ground to with the member closed while simultaneously supplying to the pile hole alongside the elongate member pile forming material, subsequently withdrawing the elongate member to cause the openable member to open and allow the pile forming material alongside the member to discharge into the thus formed hole.

Preferably the elongate member is driven by vib»atiorf.

Preferably a restriction is formed at the leading end of the elongate member when the openable member is open or partially open to cause an accumulation of pile forming material at the leading end of the member as it is withdrawn thereby ensuring that material at the restriction ensures the compaction of previously deposited material until the material in the restriction can be released and replaced by further material.

Preferably pile forming material is fed to the pile hole from a hopper of material through which the elongate member is driven.

Reinforcing means may be inserted into the pile forming material after 15 the elongate member has been removed and before the material has assumed its final form.

An embodiment of the present invention will now be described by way of example only with reference to the accompanying drawings in which:Fig. 1 shows a longitudinal perspective view, not to scale, of a pile 20 forming member; Fig. 2 shows a perspective view of the leading end of the member; , Fig. 3 shows a longitudinal cross-section through the leading end; ί Fig. 4 shows a transverse cross-section through the pile forming member; Fig. 4a and 4b show transverse cross-sections through alternative forming member; Fig. 5 shows a pile forming assembly including a hopper for pile forming material; * * Fig. 6 shows a plan view of a modified leading end of the pile forming member; and Fig. 7 shows a mounting means for a vibrator.

A pile casing 10 of a pile forming member for forming a pile by vibrating the casing into the ground to displace the earth to form a hole 12 which can be subsequently filled by pile forming material as the casing is removed, comprises circular cross-section tubular steel member 11 having a length of greater than 3 metres and a diameter of 110mm. The tubular member 11 has at its upper end, means 14 for attachment to a vibrator 16 mounted for vertical movement on a mast 18 normally carried on a tracked vehicle 20 providing a source 22 of pressurised hydraulic fluid for the vibrator 16. The casing 10 is provided with a plurality of longitudinally extending apertures 21 the total surface area of which is greater than the total surface area of the remaining casing. It is strengthened by an internal multiple arm rib 22 (Fig. 4) extending along its length, the rib having three arms 24 extending from the axis of the casing to its inner surface and being fixed thereto by welding.

An assembly 26 is provided at the leading end of the casing 10 and comprises a collar 28 by which the assembly can be readily attached to the casing 10 and removed therefrom for refurbishment, repair and servicing and four triangular shaped door members 30 hinged at their upper ends 32 to a member 34 fixed to the collar 28 in such a way that the upper end of each door meftiber abuts the member 34 when in the closed position in which the plane of each door member 30 is inclined to the longitudinal axis of the casing 10. It will be seen from Figs. 1 to 3 of the drawings that in the closed position the unconnected sides 36 of the triangular members abut the corresponding sides of neighbouring members to provide a pyramid point at the leading end of the pile forming member.

It will be realised that as the pile forming member is driven into the ground by the vibrator 16 the ground will exert a closing action on the door members 30 so that in the downwards direction the door members will remain abutted against each other in the closed position and form the pointed end of the member. As the vibrator is reversed to vibrate the pile forming member out of the hole it has formed, the door members 30 will fall, under the action of gravity, to an open or partially open position so that any material, for example concrete, within the casing 10, can escape from the casing through its, now open, end into the pile hole 12 which has been formed and from which the member is exiting.

Material leaving the casing 10 from its leading end will experience a partial restriction at the plate 34 and the vibrating action will cause material to accumulate at this restriction, effectively forming a temporary closed end for the pile forming member which will ram material previously deposited into the pile hole 12 until it is compacted to a sufficient degree to release the restriction, allowing more material to fall into the hole 12 and further material from above in the casing 10 to fall down and form a further restriction. A similar operation will occur if for any reason a door member 30 partially closes during removal of the casing 10 from hole 12.

Pile forming material is fed to the casing 10 through the longitudinal apertures 21. Material is fed as the pile forming member is driven into the hole. The casing 10 passes through an opening 40 in the base of a hopper 42 carried by the tracked vehicle 20 and is kept constantly supplied with concrete to provide a hydraulic head which ensures that concrete flows through the apertures 21 to completely fill the casing 10 as it is being driven and as it is being removed from the hole 12. The hopper 42 may be supplied from a reservoir 44 by means of a channel 46 in which is mounted a material transfer screw 48 which continuously feeds concrete to the hopper.

In a preferred embodiment, the leading end assembly 26 is provided with four radially extending fins 50, the fins being position such that they radially extend from a point near the leading end of the pile forming member * coincident with the abutment of neighbouring door metiber*30 sides. The fins form passages extending radially outwardly from the pile hole 12 in the manner described in our U.K. Patent 0464080 thereby providing a pile with a surface area which is considerably increased compared with that of a cylindrical pile at the expense of relatively low additional amounts of concrete.

A downwardly directed load may be supplied to the vibrator 16 by a winch 60 and rope 62 assembly, to pull the vibrator and the pile member down into the hole. The rope 62 may be attached directly to the vibrator or to a vibrator mounting plate 12.

Fig. 7 illustrates that additional mounting means 70 are provided between the lower end of the vibrator and the plate 72 by which it is mounted to the mast, the means comprising a linkage 74 pivotally fixed at each of its ends to the vibrator 16 and mast plate 72 to restrict the movement of the lower end of the vibrator 16 and to ensure that the energy it imparts to the pile casing 10 is directed essentially parallel to the longitudinal axis of the member.

Various modifications can be made without departing from the scope of the invention, for example three door members 30 can be provided at the leading end assembly as illustrated in Fig. 6.

In certain instances stone or ameliorated soil may be provided rather than concrete to provide the pile forming material. t '* Figs. 4a and 4b illustrate alternatives to the apertured pile casing 11.

The elongate member 70 illustrated in Fig. 4a carries any of the leading ends described above at its lower end and is driven by the vibrator 16 at its upper end. It comprises three similar components 72 each of which is formed by making two parallel cuts along a steel tube to give a component of acrcuate cross-section. Three such components are welded in back-to-back relationship to form the member illustrated in Fig. 4a. This member is rigid and does not 5 hinder the passage of pile forming material down the hole on the concave side of the components 12. In a modification (not illustrated inihe drawings) a circular cross-section bar is fixed along the length of the member at the touching edges of each pair of components.

Fig. 4b illustrates another alternative to the apertured pile casing 11.

This elongate member 80 comprises three radially extending limbs 82 welded together at the centre of the elongate member in a manner similar to the ribs 24 within the casing (Fig.4). Fig. 4b shows that to the outer end of each member is welded a longitudinally extruding circular cross-section bar 86. The provision of the bars 86 is an optional feature.

In a further modification a hammer may be provided to drive the pile into the ground but this has proven in practice to be less satisfactory than a vibrator as it is a much slower operation.

In another modification the assembly at the leading end of the column can be left down the hole when the casing is removed. In such a modification it may not be necessary to provide hinged door members.

Claims

1. Pile forming apparatus comprising an elongate member adapted to receive energy from a pile driving source at its upper end to drive it into the , ground, and having a pile tip at its leading end, the elongate member having a * 5 cross-section which lies within the perimeter of the pil^tip, And the tip including a member movable from a closed position when the elongate member is being driven to an open position when the member is being removed.

2. Apparatus according to claim 1, wherein the elongate member includes three elongate components each having an arcuate cross-section arranged in 10 back-to-back relationship with the outer end regions of each component permanently fixed to the corresponding regions of its neighbours.

3. Apparatus according to claim 1, wherein the elongate member includes a plurality of radially extending links.

4. Apparatus according to Claim 1, wherein the elongate member is a 15 hollow casing. 5. Apparatus according to claim 4, wherein the elongate member is of circular cross-section. 6. Apparatus according to any preceding claim, wherein the movable member is hinged to the elongate member at its upper end. 20 7. Apparatus according to any preceding claim, wherein the elongate member, when in its closed position, is inclined relative to the longitudinal axis of the elongate member. 8. Apparatus according to any preceding claim, wherein a plurality of hinged members are provided. 9. Apparatus according to claim 8, comprising three or four equispaced, geometrically similar hinged members. 10. Apparatus according to claim 8 or 9, wherein each hinged member, in its closed position, abuts its neighbouring members such that the assembly of 5 hinged members in the closed position forms a triangi^ar of rectangular prism or cone. 11. Apparatus according to any preceding claim, wherein the casing is apertured. 12. Apparatus according to claim 11, wherein the apertures in the casing 10 have a total surface area which is greater than the remaining casing surrounding the apertures. 13. Apparatus according to claim 11 or 12, wherein the apertures extend in the longitudinal direction of the casing. 14. Apparatus according to any preceding claim, wherein a stiffening 15 member extends through the casing. 15. Apparatus according to claim 14, wherein the stiffening members has two, three or four limbs extending radially from the central axis of the casing to the inner casing wall. 16. Apparatus according to any preceding claim, wherein preferably the 20 hinged members are mounted to a collar fixed to the leading end of the elongate member. 17 Apparatus according to any preceding claim, wherein the casing has a circailar, square rectangular, hexagonal or octagonal cross-section. 18. Apparatus according to any preceding claim, wherein the means at the top of the elongate member is adapted to connect the elongate member to a vibrator to impart energy to the casing. 19. Apparatus according to any preceding claim, wherein fins are provided on the leading end of the elongate member and extending radially therefrom, 5 each fin being located adjacent to the abutting edges o^neighbouring hinged members. 20. Apparatus according to claim 19, wherein the fins are retractable against the elongate member when the apparatus is being withdrawn from the pile hole. 21. Apparatus according to claim 19, wherein the fins are mounted to the 10 apparatus by a removable member and remain down the pile hole when the elongate member is withdrawn. 22. Apparatus according to any preceding claim, further comprising a hopper through which the elongate member extends such that fluent material in the hopper can flow down the hole made by the pile tip alongside the 15 elongate member from the hopper subsequently to flow out of the open pile tip of the apparatus as it is withdrawn. 23. Apparatus according to claim 22, comprising a supply arrangement for the hopper, the supply arrangement comprising a material reservoir discharging into a feed channel which incorporates a screw feed arrangement 20 which, on operation, transfers material from the supply reservoir to the hopper. 24. A method of forming a pile, comprising driving an elongate member having an openable member at its leading end into the ground with the member closed while simultaneously supplying to the pile hole alongside the elongate member pile forming material, subsequently withdrawing the elongate member 25 to cluse the openable member to open and allow the pile forming material alongside the member to discharge into the thus formed hole. 25. A method according to claim 24, wherein the elongate member is driven by vibration. 26. A method according to claim 24 or 25, wherein a restriction is formed at the leading end of the elongate member when the openable member is open or partially open to cause an accumulation of pile forming$material at the leading end of the member as it is withdrawn thereby ensuring that material at the restriction ensures the compaction of previously deposited material until the material in the restriction can be released and replaced by further material. 27. A method according to claim 24, 25 or 26, wherein pile forming material is fed to the pile hole from a hopper of material through which the elongate member is driven. 28. A method according to any of claims 24 to 27, wherein reinforcing means are inserted into the pile forming material after the elongate member has been removed and before the material has assumed its final form. 29. Pile forming apparatus including an elongate member adapted to be driven into the ground in which a pile has to be formed in situ, the said elongate member including three components each having an elongate crosssection, the components being fixed together in back-to-back relationship at their outer end regions. 30. Pile forming apparatus including an elongate member adapted to be driven into the ground in which a pile has to be formed in situ, the said elongate member including at least three elongate components arranged radially with respect to the central longitudinal axis of the elongate member and fixed together along their inner edges. t 31. ' Pile forming apparatus as claimed in Claim 30 or in Claim 31, in which a circular cross-section bar is fixed at the outer end of each component. 32. Pile forming apparatus substantially as described above, with reference to the accompanying drawings. 33. A method of forming a pile, substantially as described above with reference to the accompanying drawings.

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