AU723624B2 - Improved anchoring system - Google Patents

Description

TITLE: "IMPROVED ANCHORING SYSTEM" FIELD OF THE INVENTION THIS INVENTION relates to an improved anchoring system.

BACKGROUND OF THE INVENTION The invention is particularly suitable for, but not limited to, an anchoring system for stabilizing soil formulations, supporting retaining walls or piling, or the like.

In developing an anchoring system, it is necessary to ensure that the system is relatively easy to install and that the system will have long term integrity. It is important that the anchor will be securely engaged in the soil formation in which it is placed.

While anchoring in rocky soils is relatively easy, difficulties arise in reactive soils or soils with low structural strength, eg., clays, sands and reclaimed swamps.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a system where the anchor can be used in a wide range of soils.

It is a preferred object to provide a system where the anchor :oo 20 can be employed to drill its own hole in the soil formation if required.

It is a further preferred object to provide an anchor where the installation of the anchor and the grouting of the hole, can be :controlled via a single tool.

Other preferred objects will become apparent from the following description.

In one aspect, the present invention resides in an earth anchoring system including: an anchor having a body member, two or more anchor flukes pivotally mounted on the body member and movable between a o* 44 retracted position and an extended position extending substantially radially from the body member, and stop means on the body member to restrain the flukes in the extended position; a cutter head mounted on a front portion of said anchor for rotation therewith; a screw-threaded rigid tensionable anchor rod connected to the anchor for coupling to a support member, said anchor being adapted in use to be driven to a required depth in a soil formation by rotation of a tubular driving tool extending over the length of said anchor rod.

If required a cutter head may be mounted on the anchor to enable the anchor to drill its own hole in the soil formation as the anchor is rotated and advanced by said driving tool.

Alternatively a cutter head may be formed integrally with said anchor.

Suitably, the body member has a screw-threaded bore to receive one end of the anchor rod.

The anchor suitably includes three anchor flukes.

Preferably, said anchor includes stop means to limit the extent of radial extension of said anchor flukes.

If required, the anchor system may include spacer means S-having an annular hub slidably mounted on the anchor rod and a plate extending perpendicularly therefrom, the plate being arranged to engage the plates or wings and urge them towards the extended position as the 20 spacer means is advanced towards the body member by application of 0: tension on the anchor rod.

~Preferably, a nut, screw-threadably mounted on the anchor 00.• rod, is rotatable by the driving tool, having a complementary socket, to :o*°advance the spacer means along the anchor rod towards the body 25 member.

sees The driving tool may be adapted to introduce compressed %s air, water down the tool to clean the hole of debris and/or dry the soil •oo around the hole.

Grout may also be pumped down the driving tool and the 30 tool may be withdrawn when the hole is filledwith grout. Alternatively, the 4 00 driving tool may be re-engaged with the anchor after the hole has been Scleaned/dried, and grout may be pumped down the hole about said tool, 1 the tool isolating the anchor rod from the grout.

In a second aspect, the present invention also resides in a method of installing an earth anchor system, said method comprising the steps of forming a borehole in an earth formation and extending thereinto by a rotatable driving tool an anchor according to any one of claims 1 to 11; securing an apertured support member against an exposed face of a soil formation over a free end of said anchor rod extending from said borehole; and tensioning said anchor rod against said support member initially to cause said flukes to move to a radially extended anchoring position and thereafter to induce compression in said earth formation in the region between said anchor and said support member.

If required the borehole may be formed in a soft soil formation by o 15 driving the anchor member thereinto by a vibrating force applied by said driving took, with or without rotation of said anchor by said driving tool.

Suitably a source of compressed air or pressurised water is directed into said driving tool to clear the borehole of loosened soil, and, if required, to dry the interior of the borehole.

Preferably a tubular shroud having an annular space about said driving tool is associated with said driving tool to provide temporary support for the borehole wale and, if required an outlet channel for soil removed from said borehole.

In stable soil or rock formations, said borehole is suitably formed :1 25 by cutting members associated with said anchor, said anchor being rotated by said driving tool.

Suitably, during or after removal of said tubular shroud, grout is introduced into said borehole via said driving tool to reinforce the anchoring of said anchor.

30 BRIEF DESCRIPTION OF DRAWINGS WO 97/47824 PCT/AU97/00365 4 To enable the invention to be fully understood, preferred embodiments will now be described with reference to the accompanying drawings, in which: FIG 1 is a schematic sectional view showing the anchoring system used to support an excavation wall; FIG 2 is a sectional side view showing the system used to support a pile; FIG 3 is a sectional plan view of the detail A in FIG 2; FIGS 4 and 5 are respective perspective views of an anchor of a first embodiment; FIGS 6 and 7 are perspective views of an anchor of a second embodiment; FIG 8 is a perspective view of the components of the system of a third embodiment (the anchor rod being omitted); and FIG 9 is a rear view of the anchor of FIG 8.

DETAILED DESCRIPTION Referring to FIG 1, the anchoring system 10 is used to stabilize the wall 21 of an excavation 20, where a support plate 22 interconnects the anchor rod 50 of an anchor system to enable tension to be applied to the anchor rod 50 to reinforce the earth formation by induction of a compression zone between the exposed wall 21 of excavation 20 and anchor 9 at the opposite end of rod In FIGS 2 and 3, the anchoring system 10 is used to support a contoured sheet pile 23 where a tensioning plate 24 engages a pair of lock plates 25 provided against the outer face of the sheet pile 23. The screw threaded anchor ord is tensioned by threaded nut 26 after driving tool 70 (shown in phantom) is removed and a mass of grout 90 is inserted into the borehole.

Referring now to FIGS 4 and 5, an anchor 40 has a body 41 with a screw-threaded bore 42. Three flanges 43 extend substantially radially from the body 41 and an anchor fluke 44 is hingedly mounted on WO 97/47824 PCT/AU97/00365 each flange 43 via a hinge pin Each flange 43 has an abutment face 46 to limit the radial extension of the anchor plates 44.

The plates 44 are swung downwardly in the direction of the arrows B to be substantially parallel to, but trail, the body 41 when the anchor 40 is advanced down the hole.

In the modified embodiment of FIGS 6 and 7, a hole cutter is mounted at the forward end of the body 41 to cut the hole for the anchor 40 as it is rotated and advanced. The cutter has a blade 81, with cutting tip 82, and a shank 83 received in the bore 42 of the body 41. A spacer 84 is interposed between the blade 81 and the anchor body 41.

FIGS 8 and 9 show a modified form of the anchor where the tips of the anchor plates 44 have V-shaped recesses 48 to form soil engaging tips 49.

As an alternative to hole cutter 80, the leading shoulders 43a of flanges 43 may be tapered to form a cutting edge and, if required, faced with a Stellite (TM) or similar hard facing for cutting purposes.

An insert spacer 60 has a tubular body 61, with a plain bore 62, and a hexagonal plate 63. A nut 64, has a screw-threaded bore engageable with the tension rod A driving tool 70, with a socket 71 at one end is operable to rotate the nut 64 to advance the spacer 60 towards the body 41 of the anchor 40, the plate 63 engaging the anchor flukes 44 and causing them to be swung out from the retracted position in FIG 8 to the extended position in FIG 9.

The operation of the anchoring system 10 will now be described.

The hole 11 for the anchoring system may be pre-drilled by a conventional earth boring drill. However, it is preferred that a cutting anchor 40 mounted on the anchor rod 50, be rotated and advanced by the driving tool coupled to a drive system of an excavator or the like to drill the WO 97/47824 PCT/AU97/00365 6 hole 11. During this stage, the anchor plates 44 are retracted and lie along the anchor rod 50 see FIG 8.

In rocky soils, the driving tool 70 is inserted down the hole 11 with anchor rod 50 located therein. At a required borehole depth, the socket 71 is engaged with the nut 64 and the cutter is rotated to advance the insert spacer 60 towards the body 41 of the anchor, causing the anchor plates 44 to be swung outwardly into engagement with the soil around the hole 11. The driving tool 70 is retracted to release the socket 71 from the nut 64.

Compressed air is pumped down the bore of the driving tool and as it flows up the annular space defined by the hole 11 and the tool 70, it clears debris from the hole 11 and dries the hole wall.

Grout 90 can be pumped down the tool 70 and the operator is aware that the hole 11 is full of grout when it fills the annular space between the tool 70 and the hole wall. The tool 70 may be withdrawn from the hole 11 for re-use.

The anchor rod 50 is then pre-tensioned as shown in FIG 1, or FIGS 2 and 3, to prestress the grout 90 before it sets. After about 24 hours the anchor rod may be fully stressed to a required limit.

In certain applications, the tool 70 may be re-engaged with the nut 64, after the compressed air is pumped down the tool, to enclose the anchor rod 50 to protect the latter from grout 90 pumped down the annular space defined by the tool 70 and the hole wall.

It will be readily apparent to the skilled addressee that the driving tool 70 can have several functions to drive the anchor to a required depth by vibration in soft soils or, with a cutting head to rotate the anchor to form the borehole, to direct a source of pressurized fluid to clear the borehole of loosened earth, to open the anchor plates 44 to engage the anchor 40 in the hole 11, and as a grout tube when the hole 11 is filled with grout.

The anchor 40 can have two or more anchor plates 44 and WO 97/47824 PCT/AU97/00365 7 can be used in a wide range of soils, eg., clay, sand, shale, reclaimed swamp, rock, etc. The system 10 can be used in a wide array of applications where structural support is required.

To increase the strength of the system, the anchor 40 can be rotated by the anchor rod 50 with the anchor plates 44 extended to form a cavity about the anchor to enable formation of an enlarged mass of grout or a "deadman" to be formed when grout is pumped down driving tool 70. This increases the holding power of the anchor in the earth formation.

In an alternative embodiment, two or more of the anchors can be provided along the anchor rod 50 at spaced intervals.

Various changes and modifications may be made to the embodiments described and illustrated without departing from the scope of the present invention.

Claims (18)

1. An earth anchoring system including: an anchor having a body member, two or more anchor flukes pivotally mounted on the body member and movable between a retracted position and an extended position extending substantially radially from the body member, and stop means on the body member to restrain the flukes in the extended position; a cutter head mounted on a front portion of said anchor for rotation therewith; a screw-threaded rigid tensionable anchor rod connected to the anchor for coupling to a support member, said anchor being adapted in use to be driven to a required depth in a soil formation by rotation of a tubular driving tool extending over the length of said anchor rod.

2. A system as claimed in claim 1 wherein the cutter head is 15 formed integrally with said anchor.

3. A system as claimed in claim 1 wherein said cutter head is removably attached to said anchor.

4. A system as claimed in any one of claims 1 to 3 wherein the body member has a screw-threaded bore to receive one end of the anchorrod.

A system as claimed in any preceding claim wherein the anchor includes three anchor flukes.

6. A system as claimed in any preceding claim wherein said o° anchor includes stop means to limit the extent of radial extension of said 25 anchor flukes. coco

7. A system as claimed in any preceding claim wherein the SS anchor system includes spacer means having an annular hub slidably mounted on the anchor rod and a plate extending perpendicularly therefrom, the plate being arranged to engage said flukes and urge them towards the extended position as the spacer means is advanced towards the body member by application of tension on the anchor rod.

A system as claimed in claim 7 wherein a nut, screw- threadably mounted on the anchor rod, is rotatable by the driving tool, having a complementary socket, to advance the spacer means along the anchor rod towards the body member.

9. A system as claimed in any preceding claim wherein the driving tool is adapted to introduce pressurized air or water down the tool to clean a borehole-of debris and/or dry the soil around the anchor.

A system as claimed in any preceding claim wherein grout may be pumped down the driving tool to fill part or all of the borehole with grout.

11. A system as claimed in any one of claims 1 to 9 wherein the driving tool may be re-engaged with the anchor after the hole has been cleaned/dried, and grout may be pumped down the borehole about said tool between said anchor rod and a wall of said borehole.

12. A method of installing an earth anchor system, said method comprising the steps of forming a borehole in an earth formation and extending thereinto by a rotatable driving tool an anchor according to any one of claims 1 to 11; a securing an apertured support member against an exposed face of a soil formation over a free end of said anchor rod extending from said borehole; and tensioning said anchor rod against said support member •o ooI initially to cause said flukes to move to a radially extended anchoring ;position and thereafter to induce compression in said earth formation in a.. the region between said anchor and said support member.

13. A method as claimed in claim 12 wherein the borehole may be formed in a soft soil formation by driving the anchor member thereinto by a vibratory force applied by said driving tool. *0

14. A method as claimed in claim 12 or claim 13 wherein a ""30 source of compressed air or pressurized water is directed into said driving tool to clear the borehole of loosened soil, and, if required, to dry the Sinterior of the borehole. I

15. A method as claimed in any one of claims 12 to 14 wherein I'^ 1 r a tubular shroud having an annular space about said driving tool is associated with said driving tool to provide temporary support for the borehole wall and, if required, an outlet channel for soil removed from said borehole.

16. A method as claimed in any one of claims 12 to 15 wherein during or after removal of said tubular shroud, grout is introduced into said borehole via said driving tool to reinforce the anchoring of said anchor.

17. An earth anchoring system substantially as hereinbefore described with reference to the accompanying drawings.

18. A method of installing an earth anchor system substantially as hereinbefore described with reference to the accompanying drawings. DATED this Twenty-ninth day of June 2000. TRISTANAGH PTY LTD by its Patent Attorneys FISHER ADAMS KELLY *ooo* *o