GB2221712A

GB2221712A - Forming piles in situ

Info

Publication number: GB2221712A
Application number: GB8918509A
Authority: GB
Inventors: Joseph Edwards
Original assignee: Individual
Current assignee: Individual
Priority date: 1988-08-12
Filing date: 1989-08-14
Publication date: 1990-02-14
Anticipated expiration: 2009-08-14
Also published as: GB8918509D0; IE882465L; GB2221712B; IE61789B1

Abstract

A cast-in-place load bearing pile is formed by drilling a hole (1) using a drilling bit (3) and lining the hole with a casing (5). Liquid concrete is poured into the hole and the outer casing (5) is removed when the concrete is partially set. Reinforcing members may then be inserted into the concrete. <IMAGE>

Description

A METHOD AND APPARATUS FOR PILING The invention relates to a method and apparatus for forming a pile.

In this specification the term "pile" refers to a long slender member of reinforced cementitious material in the ground to carry a vertical load, to resist a lateral force, and/or to resist water or earth pressure.

Conventional methods for forming a pile are time consuming.

The time taken to form a grid of piles in constructing a foundation can be of critical importance in the construction schedule. It is essential therefore, that the piles be formed as quickly as possible.

A number of methods are known for forming load bearing piles.

In one known arrangement an auger device is driven into the ground to form a bore. The auger is then withdrawn from the bore which is then filled with concrete. A major disadvantage of this method however, is that the walls of the bore are easily eroded and mix with the concrete prior to setting, weakening the pile and rendering it ineffective.

In another known arrangement a mandrel is driven into the ground by a percussive technique to form the bore. As the mandrel is driven into the bore liquid concrete is poured into the bore. The pressure exerted on pouring of the concrete, however, may lead to erosion of the bore sidewall with similar problems to those described in the first known method.

Not only are such known methods time consuming but also if a pile is found on testing to be ineffective it must be removed and replaced. This involves considerable expense and difficulty, not only in replacing the pile but also, and generally more importantly, in severe disruption of construction scheduling.

This invention is directed towards providing a method and apparatus for rapidly and effectively forming such load bearing piles.

According to one aspect of the invention there is provided a method of forming a cast-in-place pile comprising the steps of: drilling a hole in the ground in which the pile is to be sited; reinforcing the hole with an outer casing; removing the drill bit from the hole, leaving the casing in the hole; filing the hole with a pile forming material; and inserting reinforcing means into the pile forming material.

In one embodiment of this aspect of the invention the casing is carried behind the drill bit during drilling.

Preferably the casing is removed on partial setting of the pile forming material.

Preferably the reinforcing means is inserted after the casing is removed.

In a particular preferred embodiment of the invention the drill used is of the ODEX type supplied by Atlas Copco.

In another aspect the invention provides an apparatus for forming a support pipe comprising a mast for supporting a drilling bit and a pile hole casing for insertion into a hole, a frame supporting the mast, and mounting means for mounting the frame to a support, preferably a support vehicle.

In a preferred embodiment of this aspect of the invention the frame is pivotally mounted to the mast and support vehicle.

In a particularly preferred embodiment of this aspect of the invention the support frame comprises an A - frame support extending between the mast and a support vehicle.

In one embodiment of this aspect of the invention tilting means are provided for tilting the mast for insertion and withdrawal of the drill and casing, and if required for forming a raking pile hole.

Preferably the tilting means comprising a ram extending between the mast and the vehicle support.

In a particularly preferred embodiment of this aspect of the invention the drill is of the ODEX type supplied by Atlas Copco.

The invention will be more clearly understood from the following description thereof given by way of example only with reference to the accompanying drawings in which: Figs. 1 to 5 are diagrammatic side, partially cross sectional views illustrating the method and apparatus of forming a pile according to the invention, and Fig. 6 is a diagrammatic side view of an apparatus for forming a pile.

Referring to the drawings and initially to Figs. 1 and 5 thereof, the method of forming a structural support pile according to the invention comprises the steps of first drilling a hole 1 in ground 2 in which a pile is to be sited.

The hole 1 is drilled by overburden drilling by the eccentric method, preferably by using an ODEX system manufactured by Atlas Copco of Sweden. A drilling head 3 is carried by a drill string 4 and a casing 5 is carried down to the hole as it is drilled so that the hole 1 is lined at the same time as it is being drilled. During the drilling operation a lower reaming part of the drill bit 3 swings out as illustrated in Fig. 1 and drills a hole which is larger in diameter than the external diameter of the casing tube 5. When the required depth has been reached, the rotation of the drill bit 3 is reversed and the lower reaming section of the drill bit swings inwardly into a minimum diameter configuration illustrated in Fig. 2 and may be lifted up through the casing 5. The casing 5 is- left in the hole 1 as illustrated in Fig. 2.To form a pile, the hole is then filed with liquid concrete 6 as illustrated in Fig. 3. Before the concrete 6 has set the casing 5 is removed from the hole as illustrated in Fig. 4 and reinforcing bars 7 are inserted down through the concrete 6 in the hole causing the concrete to completely fill the hole and reinforcing the concrete on setting as illustrated in Fig. 5.

Referring to Fig. 6 there is illustrated an apparatus according to the invention indicated generally by the reference numeral 10 forming a support pile as described with reference to Figs. 1 to 5. The apparatus 10 comprises a mast 11 for supporting the drill bit string and outer casing 5 and a frame 12 for supporting the mast 11. The support 12 extends between the mast 11 and a support vehicle which is a suitable wheeled or track vehicle 15. Mounting means for mounting the frame 12 to the support vehicle 15 and mast 11 comprises a first pivot mounting 20 which is provided on a mast attachment frame 25 on the mast 11 and a second lower mounting 26 provided on the support vehicle 15. A turntable may be provided between the frame 25 and mast 11 to give side slew on each side of the vertical. For added strength in this case the support 12 comprises an A - frame support. An adjustable locking strut 30 may be provided between the vehicle 15 and mast 11 at the lower end thereof.

Means for tilting the mast 11 for insertion and withdrawal of the drill bit string and casing, and if required for forming a raking pile hole, in this case comprises a ram 35 extending between the mast 11 and the vehicle 15. The mast 11 is provided with pivot footings 35 at the lower end thereof.

The invention provides a method and apparatus for forming a pile which allows piles to be formed very quickly and easily which speeds up the construction process as foundation work may be carried on more quickly then heretofore.

The invention is not limited to the embodiments hereinbefore described which may be varied in both construction and detail.

Claims

1. A method of forming a load bearing cast-in-place pile comprising the steps of: drilling a hole in the ground in which the pile is to be sited, reinforcing the hole with an outer casing, removing the drill bit from the hole while leaving the casing in the hole, and filling the hole with a pile forming material.

2. A method as claimed in Claim 1 wherein the method includes the step of inserting reinforcing means into the pile forming material.

3. A method as claimed in Claim 1 or 2 wherein the outer casing is carried into the hole behind the drill bit as the hole is being drilled.

4. A method as claimed in any of Claims 1 to 3 wherein the casing is removed on partial setting of the pile forming material.

5. A method as claimed in Claim 4 wherein the reinforcing means is inserted after the casing is removed.

6. A method as claimed in any preceding claim wherein the drill bit is of the ODEX TM type.

7. A method substantially as hereinbefore described with reference to the accompanying drawings.

8. Apparatus for forming a load bearing pile by the method of any preceding claim comprising a mast for supporting a drilling bit, a pile hole outer casing for insertion into a hole, a frame supporting the mast, and mounting means for mounting the frame to a support.

9. Apparatus as claimed in Claim 8 wherein the support is a tracked vehicle.

10. Apparatus as claimed in Claim 9 wherein the frame is pivotally mounted to the mast and the support vehicle.

11. Apparatus as claimed in Claim 9 or 10 wherein the support frame comprises an A - frame support extending between the mast and the support vehicle.

12. Apparatus as claimed in any of Claims 8 to 11 wherein means are provided for tilting the mast for insertion and withdrawal of the drill and casing, and if desired, for forming a raking pile hole.

13. Apparatus as claimed in Claim 12 wherein the tilting means comprises a ram extending between the mast and the support vehicle.

14. Apparatus as claimed in any of Claims 8 to 13 wherein the drill bit is of the ODEX TM type.

15. Apparatus substantially as hereinbefore described with reference to the accompanying drawings.