GB2108185A - Method of boring pile boles - Google Patents

Abstract

A method and equipment for boring a pile hole in the ground, wherein (a) a readily demountable and portable tripod framework 15 is erected around and above the intended hole location, (b) a remote- controlled electrically powered, motor- driven hoist mechanism 14 is suspended from the tripod, and (c) an i.c. engine-powered drill 16 with auger-like drill bit is suspended from the hoist mechanism, the drive shaft to the drill bit being extendible by one or more extension rods. The drill bit may be replaced, e.g. the end of drilling, by an inwardly collapsible reamer. <IMAGE>

Description

SPECIFICATION Method and equipment for providing boreholes in the ground for piles This invention relates to the provision of bore holes in the ground for piles, e.g. on smallscale building sites, and in particular to methods and equipment therefor.

It is known to provide a short-depth hole for a fencing post by drilling a bore in clay soil with a motor-driven drill, e.g. having a helical or worm-like auger drill bit. In use the motordriven drill is held by two men and raised manually at intervals to remove the soil and/or to extend the drive shaft to the drill bit, e.g. by adding extension rods. This is a cumbersome operation and the depth to which the hole may be bored is limited (e.g. to about 2.5m) not least by the height to which the two men can manually lift the motor-driven drill.

Accordingly this prior art method is generally unsuitable for small-scale and/or restricted access building sites (such as house extensions) where it is desirable to provide several deep piling bores at intervals spaced along a shallow so-called strip footing, i.e.

foundation channel, rather than provide a non-piled, deep strip footing at far greater expense. Clearly portable equipment capable of providing deep bore holes in the ground for piles and which can be used on small-scale and/or restricted access building sites (e.g.

the rear of a terraced house), and a method of using such portable equipment, have been needed for many years and these needs have certainly been increased since the issuance of stricter building regulations or requirements, e.g. National House Building Council Practice Note 3, October 1 969 revised April 1 974.

This long-felt need can naturally not be met by adopting the large-scale boring techniques of the gas or oil exploration industry which involve massive, permanent structures such as derricks and the like.

According to a first aspect of this invention there is provided a method of providing a piling hole in the ground comprising the steps of (a) determining the location for said piling bore hole, (b) erecting a readily de-mountable and portable space frame around and above said location, (c) mounting a hoist mechanism from said space frame vertically above said location, (d) suspending a motor-driven drill, with its drill bit lowermost, from said hoist mechanism such that the drill can have a lowered and raised position, depending on the operating condition of the hoist-mechanism, and, (e) in repeated sequence, operating said drill whilst in said lowered position and operating the hoist mechanism to bring the drill to said raised position for the withdrawal of soil or other ground material.

Conveniently, at intervals in the sequence and whilst said drill is in said raised operation, the drive shaft to the drill bit may be extended, e.g. by the insertion of one or more extension rods.

Advantageously, the drill-bit (e.g. a helical or worm-like auger) is replaced at an interval in said sequence or at the end of drilling, by an inwardly collapsible reamer to provide, below ground level, a cavity of wider diameter than the drilled bore. Where this cavity is provided at the end of drilling at the bottom of the bore, and the bore and cavity are then filled with concrete to provide the pile, the cavity-contained concrete constitutes a larger area foot for the pile. Such an arrangement allows for piles to be formed of lesser diameter requiring a correspondingly lesser quantity of concrete and of ground material removal.

According to a second aspect of this invention there is provided equipment for use in providing a piling bore hole in the ground, said equipment comprising: a readily de-mountable and erectable, portable, space frame of which a part is spaced above ground when the frame is erected, first connection means located on said part of the frame, a hoist mechanism having second connection means for interconnection with said first connection means to permit the hoist mechanism to depend from said part of the erected frame, and a motor-driven drill adapted to be carried by said hoist mechanism with the drill bit lowermost.

Preferably the space frame comprises a plurality of legs which, when the space frame is erected, are mutually inclined and approach one another as they extend upwardly. The said legs may be extendible, e.g. by being telescopic or by means of additional components couplable thereto. Preferably said space frame is a tripod having telescopic legs.

Preferably said hoist mechanism is motordriven, e.g. electrically powered and provided with a remote control unit.

Preferably the equipment comprises an inwardly collapsible reamer interchangeable with said drill bit. The drill bit is conveniently a worm-like or helical auger. Advantageously the equipment comprises a plurality of extension rods for extending the length of the drive shaft to the drill bit.

According to a third aspect of this invention there is provided a reamer for enlarging the diameter of part of a borehole in the ground below ground level, said reamer comprising (a) a container for removal of reamed out ground material, said container having a base member and a wall member upstanding therefrom, (b) at least one reaming blade extendible laterally outwardly from and retractable laterally inwardly of the container, (c) a drive member to rotate the container and the reaming blade(s), said drive member being axially movable with respect to the container, and (d) means to effect said outwards extension and inwards retraction of the blade(s), said means being responsive to said axial movement between the container and the drive member.

Preferably the base member of said container is relatively movable with respect to a central stem constituting said drive member, the or each said blade is articulated to said stem, and said means comprise a linkage pivotally connecting said base member to said blade(s).

By way of non-limiting example, one embodiment of this invention will now be described with reference to the accompanying drawings of which Figure 1 is a schematic illustration in side elevation of equipment according to this invention, Figure 2 is a schematic perspective view of part of the equipment of Fig. 1 incorporating a drill bit, Figure 3 is a schematic vertical section through a reamer to replace the drill bit of Fig. 2, and Figure 4 is a plan view of the reamer of Fig.

3.

The equipment illustrated schematically in Figs. 1 and 2 is to be used to provide a piling bore hole 11 in clay soil 1 2 at a predetermined location 1 3 along a shallow strip footing (not shown). The equipment 10 comprises a hoist mechanism 1 4 that is suspended from a space frame 1 5 and itself carries a motordriven drill 16.

The space frame 1 5 consists of a tripod whose three legs 1 7 are pivotally attached as by trunnions 1 8 to the underside of a steel disc 20 such that, when the tripod space frame 1 5 is erected, the legs 1 7 are mutually inclined and approach one another as they extend upwardly. The three legs 1 7 are each extendible, e.g. either by being telescopic (not shown) or by coupling together additional tubular sections, e.g. aluminium scaffolding tubing. Such coupling may conveniently be achieved by cross pins 21 inserted transversely through a hole 21 a in one section end 22 into a corresponding hole 21 b in a stub projection 23 of the adjacent section end 24.The feet 1 9 of the tripod space frame 1 5 may be adjustable in height and angle to cater for undulations in the ground's upper surface 25. An eyebolt 26 is attached centrally to the underside of disc 20.

The hoist mechanism 14 is a remote-controlled, electrically powered, motor driven, hoist mechanism comprising a single block tackle substantially enclosed within a housing 27 from the bottom of which extends a chain runner 31 having a hook 32 at its lowermost end. The housing 27 is provided on its upper surface with a hook 28. The hoist mechanism 14 is suspended from the erected space frame tripod 1 5 by interconnecting hook 28 into eyebolt 26 depending from the tripod's disc 20. Power to the electric motor drive for the hoist mechanism is provided by the domestic mains voltage supply, e.g. 240 volts, and the operation and control of the electric motor is effected by a remote control unit 30 connected via a cable 29 to the electric motor in housing 27.

The drill 1 6 is provided with a metal handling frame 33 by which it is suspended from the hoist mechanism's hook 32, e.g. via an intermediate length of chain 34. The metal handling frame 33 has an outline shape somewhat like a figure-8 and, for example, 1.2m in overall length. A smaller, somewhat cube-shaped, metal sub-frame 36 is attached centrally to the underside of handling frame 33. The drill's power unit 37 comprises an 80cc, 2-stroke petrol fuelled, internal combustion engine, clutch and gearbox. This power unit 37 is mounted in the cube-shaped subframe 36 and a throttle control cable 47 for power unit 37 leads therefrom to the end of handling frame 33. The power unit's gearbox is provided with a stub shaft 38 which depends from the sub-frame 36 and provides the output drive to the drill bit 40 via a tubular drive shaft 39.The latter is extendible by coupling together a plurality of tubular sections, e.g. by inserting cross pins 41 transversely through a hole 41 a in one section end 42 and into a corresponding hole 41 b in a stub projection 43 of the adjacent section end 44. The drill bit 40, which is similarly coupled to the extendible drive shaft 39, comprises a 1 metre long central stem of cast aluminium alloy and, attached spirally thereto, a helical or worm-like steel blade of 10 to 65cm (4 to 24 inch) diameter. The drill bit 40 is thus a helical or worm-like auger.

Preliminary to operation on a restricted access site, the portable space frame tripod 1 5 is erected over the intending piling bore hole location 1 3. The hoist mechanism 14 is connected to the tripod space frame 1 5 by interconnecting parts 26 and 28. The height of the tripod space frame 1 5 is adjusted to that appropriate to the depth of piling bore hole required, e.g. to a height of disc 20 up to 6m above the grouhd surface 25. Cable 29 is secured, e.g. to one leg 17, to avoid an electrical mishap, the control unit 30 is connected to the mains supply voltage (240 volts) and operated to bring the hoist mechanism's hook 32 to a lowered position. The drill 1 6 is then suspended from the hook 32 (or otherwise suspended from the lower end of chain 31).

The actual operating cycle is as follows.

Utilising the handling frame 33, two workmen position the drill bit 40 onto location 1 3. The drill's power unit 37 is then operated by one of the workmen actuating the throttle control cable 47. As the drill bit 40 rotates, the hoist mechanism 14 is operated gradually to allow for lowering of the drill. After an interval the hoist mechanism is operated to raise the drill and permit its withdrawal from the hole thus far created. Removed clay, soil, and/or other ground material is also withdrawn and, when power unit 37 is stopped, such material adhering to the drill bit 40 may also be removed. The drill bit 40 is then re-positioned over the bore hole and the hoist mechanism 14 operated to lower the drill once again.If necessary or desirable, e.g. if the hole depth is approaching the drive shaft length and a greater depth is required, the stub 38 is disconnected or uncoupled from the remainder of the drive shaft, the hoist mechansim 14 is operated to raise frames 33, 36 and the power unit 37, and an additional tubular drive shaft section is coupled by its upper end to the stub 38 and by its lower end to the remainder of the drive shaft (e.g. the top of the drill bit 40) thereby to extend the length of the drive shaft from stub 38 to drill bit 40.

The drill's power unit 37 is then again operated and the actual operating cycle is repeated until the desired depth of piling bore hole 11 is achieved, e.g. up to, say a maximum of 6m.

In an alternative procedure, rather than coupling it always to stub 38, each additional extension section of the drive shaft 39 is always to the drill bit 40 after the latter is uncoupled from the remainder of the drive shaft above it.

If desired, the bore hole 11 may be reamed out below ground level 25-preferably at the bottom of the bore hole 11-by means of a reamer 50 (Figs. 3 and 4) which is connected to the drive shaft 39 in place of the drill bit 40. The schematic axial section of Fig. 3 illustrates the reamer both in its inwardly collapsed, retracted, out-of-use condition (to the left of the centre line) and in its outwardlyextended, in use condition (to the right of the centre line).

As shown, the reamer 50 comprises a central stem 49 which is connectable to the drill stub 38 or the lowermost drive shaft section by inserting a cross pin 51 transversely through a hole 41 a in the lowermost section end 42 and into a corresponding hole 51 b in a stub projection 53 of the stem's upper end 52. At its lower end, the stem 49 is provided with a square-section drive bore 54 which drivingly engages a mating stub shaft 55 that is mounted slidably in said drive bore 54. The stub 55 projects centrally upwardly from the disc-like base 56 of a generally bucket-shaped container 57. The cylindrical wall 58 of con tainer 57 is provided with two diametrically opposite apertures 59.

Two reaming blades 60 of somewhat tra pezium-like outline are arranged diametrically of container 57 for extension and retraction through the apertures 59. Each blade 60 is located adjacent to a vertical edge 589 of a part of the wall 58 defining that end of the associated aperture 59 (Fig. 4). When the blades 60 are in their inwardly retracted con dition, the two, substantially parallel, long and short edges 61, 62 of each reaming blade 60 are respectively nearer stem 49 and nearer aperture 59 (Fig. 3). The two mutually divergent edges 63, 64 of each trapezium shaped reaming blade 60 join the two edges 61, 62 adjacent respectively the bottom and top of the blade.A pivot pin 65, e.g. a bolt or rivet, extends through each blade 60 in the vicinity of the arris between blade edges 61 and 64, and also through a pair of associated brackets 66 projecting laterally of the central stem 49 (near its upper stub end 53) and disposed one to each side of the blade 60.

Each blade 60 is thus articulated to the cen tral stem 49.

Two link members 68 are provided, each being pivoted by its upper end 67 to the approximate centre of an associated blade 60 and by its lower end 69 to a pair of associ ated brackets 70 upstanding from the disc-like base 56 of container 57 and disposed one to each side of the link member. The pivotal connection of each link member's upper end 67 is by means of a short threaded stud bolt 71 welded to blade 60, a nut 72 being threaded onto stud bolt 71 to hold captive the link member 68. The pivotal connection of each link member's lower end 69 is by means of a headed bolt 73 and nut 74, the bolt's shank extending through the pair of brackets 70 and the end 69 between them. Triangular bracing pieces 78 are welded to the container base 56 and to the brackets 70 to reinforce the latter.Reinforcing struts 78 may extend diametrically between the central stem 49 and the cylindrical wall 58 adjacent edge 589.

These struts may optionally consist of vertical walls.

The edges 62, 63 of each blade 60 are sharpened and bent to be each directed anti clockwise (when viewed as in Fig. 4) generally arcuately or tangentially of its generatrix and such as to dig in to the soil, clay or other ground material to be reamed out.

In use, after the bore hole 11 of appropriate depth has been drilled using drill bit 40, the drill 1 6 is raised and the drill bit 40 is uncoupled from the drive shaft 39. The reamer 50 is then coupled to the drive shaft 39 in place of the drill bit 40, and the drill then lowered via hoist mechanism 14. The weight of the bucket-like container 57 and of the blades 60 articulated about pivot pins 65 ensure that the reaming blades 60 are in their inwardly withdrawn or retracted position, shown on the left of Fig. 3, and stub shaft 55 is at the bottom of its stroke in mating bore 54. When the reamer 50 reaches the bottom of the bore 11, the load of the drill 1 6 is transmitted via stem 49, brackets 66, blades 60, link members 68 and brackets 70 onto the disc-like base 56 of container 57.This transmitted load continuously urges brackets 66 and 70 towards one another and hence continuously urges the blades 60 radially outwards away from stem 49 and through apertures 59. When the power unit 37 is operated, the drive shaft 39 and stem 49 rotate and, via drive engagement of bore 54 and stub shaft 55, cause anticlockwise rotation of container 57 (when viewed as in Fig. 4). The combination of such rotation and the outwards urging of blades 60 effects a reaming action by blade edges 62, 63 which move progressively outwards as more and more gound material is removed and deflected inwardly of container 57 through the apertures 59. When the container is full, rotation is stopped and the hoist mechanism 1 4 operated to withdraw the reamer from the bore hole.As soon as a lift force is imparted to the reamer's stem 49, the compressive load, acting via link members 68 between brackets 66 and 70, is removed whereby the blades 60 can regain their inwardly retracted positions and not obstruct upwards withdrawal of the reamer.

It will be appreciated that reamer 50 can also be used for reaming below ground level 25 yet above the bottom of the bore hole 11.

To achieve this the hoist mechanism 14 is operated to locate and hold the reamer 50 at the desired intermediate vertical location in the bore hole 11, and a downward force is applied to the radially inner ends of the upper edges of the blades 60. The force can be applied, for example via a rod or tubular member encompassing the drive shaft 39, to a collar (not shown) that encircles the stem 49 and rests on the upper edges 64 of the blades 60. The dimensions of the collar and/or the shape of the blades in the vicinity of the pivot pin 65 and/or the location of pivot pin 65 adjacent the arris between the edges 61, 64 may be readily designed to ensure that adequate leverage can be applied to the blades 60 by the downwards force applied. Spaced above the container base 56, a disc may be welded to the central stem 49 and the container wall 58. The disc is apertured to permit passage therethrough of link members 68, and in use supports removed ground material and avoids it pushing base 56 axially away from stem 49.

Claims (1)

1. A method of providing a piling bore hole in the ground comprising the steps of (a) determing the location for said piling bore hole, (b) erecting a readily de-mountable and portable space frame around and above said location, (c) mounting a hoist mechanism from said space frame vertically above said location, (d) suspending a motor-driven drill, with its drill bit lowermost, from said hoist mechanism such that the drill can have a lowered and raised position, depending on the operating condition of the hoist-mechanism, and, (e) in repeated sequence, operating said drill whilst in said lowered position and operating the hoist mechanism to bring the drill to said raised position for the withdrawal af soil or other ground material.

2. A method according to Claim 1 wherein, at intervals in the sequence and whilst said drill is in said raised position, the drive shaft to the drill bit is extended.

3. A method according to Claim 2, wherein the drive shaft is extended by inserting, i.e. adding, one or more extension rods.

4. A method according to any preceding Claim, wherein the drill bit is replaced at an interval in said sequence by an inwardly collapsible reamer to provide, below gound level, a cavity of wider diameter than the drilled bore.

.5. A method according to Claim 4, wherein the drill bit is replaced by said reamer at-the end of drilling to provide said cavity at the bottom of the bore.

4. A method according to Claim 1 and substantially as herein described.

7. Equipment for use in providing a piling bore hole in the ground, said equipment comprising: a readily de-mountable and erectable, portable, space frame of which a part is spaced above ground when the frame is erected, first connection means located on said part of the frame, a hoist mechanism having second connection means for interconnection with said first connection means to permit the hoist mechanism to depend from said part of the erected frame, and -a motor-driven drill adapted to be carried by said hoist mechanism with the drill bit lowermost.

8. Equipment according to Claim 7, wherein the space frame comprises a plurality af legs which, when the space frame is erected, are mutually inclined and approach one another as they extend upwardly.

9. Equipment according to Claim 8, wherein said legs are extendible.

1 0. Equipment according to Claim 8 or Claim 9, wherein said legs are telescopic.

11. Equipment according to Claim 8 or Claim 9, wherein said legs are extendible by means of additional components couplable thereto.

1 2. Equipment according to any one of Claims 7 to 11, wherein said space frame is a tripod.

1 3. Equipment according to any one of Claims 7 to 12, wherein said hoist mechanism is motor-driven.

14. Equipment according to any one of Claims 7 to 13, wherein said hoist mechanism is electrically powered and is provided with a remote control unit.

1 5. Equipment according to any one of Claims 7 to 14 and further comprising a plurality of extension rods for extending the length of the drive shaft to the drill bit.

1 6. Equipment according to any of Claim 7 to 15, wherein said drill bit is a helical or worm-like auger.

1 7. Equipment according to any one of Claims 7 to 1 6 and further comprising an inwardly collapsible reamer interchangeable with said drill bit.

1 8. Equipment according to Claim 17, wherein said reamer comprises (a) a container for removal of reamed out ground material, said container having a base member and a wall member upstanding therefrom, (b) at least one reaming blade extendible laterally outwardly from and retractable laterally inwardly of the container, (c) a drive member to rotate the container and the reaming blade(s), said drive member being axially movable with respect to the container, and (d) means to effect said outwards extension and inwards retraction of the blade(s), said means being responsive to said relative axial movement between the container and the drive member.

19. Equipment according to Claim 18, wherein the base member of said container is relatively movable with respect to a central stem constituting said drive member, the or each said blade is articulated to said stem and said means comprise a linkage pivotally connecting said base member to said blade(s).

20. Equipment for use in boring a pile hole in the ground, substantially as herein described with reference to and/or as illustrated in the accompanying drawings.

21. A reamer comprising (a) a container for removal of reamed out ground material, said container having a base member and a wall member upstanding therefrom, (b) at least one reaming blade extendible laterally outwardly from and retractable inwardly of the container, (c) a drive member to rotate the container and the reaming blade(s), said drive member being axially movable with respect to the container, and (d) means to effect said outwards extension and inwards retraction of the blade(s), said means being responsive to said relative axial movement between the container and the drive member.

CLAIMS (21 Jan 1983)

1. A method of providing a piling bore hole in the ground comprising the steps of (a) determining the location for said piling bore hole, (b) erecting a readily de-mountable and portable space fram around and above said location, (c) mounting a hoist mechanism from said space frame vertically above said location, (d) freely suspending a motor-driven drill, with its drill bit lowermost, from said hoist mechanism such that the drill can have a lowered and raised position, depending on the operating condition of the hoist-mechanism, and, (e) in repeated sequence, operating said drill whilst in said lowered position and operating the hoist mechanism to bring the drill to said raised position for the withdrawal of soil or other ground material.

7. Equipment for use in providing a piling bore in the ground, said equipment comprising: a readily de-mountable and erectable, portable, space frame of which a part is spaced above ground when the frame is erected, first connection means located on said part of the frame, a hoist mechanism having second connection means for interconnection with said first connection means to permit the hoist mechanism to depend from said part of the erected frame, and a motor-driven drill adapted to be carried by and be freely suspended from said hoist mechanism with the drill bit lowermost.