AU781681B2 - Anchor elements and methods and apparatus for fabricating anchor elements - Google Patents

Description

Regulation 3.2

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

(ORIGINAL)

Name of Applicant: Actual Inventor(s): Address for Service: Invention Title: SCREW IN TECHNOLOGIES PTY. LTD.

DALE ANDERSON and PETER YTTRUP SANDERCOCK COWIE 69 Robinson Street, DANDENONG VIC 3175 ANCHOR ELEMENTS AND METHODS AND APPARATUS FOR FABRICATING ANCHOR

ELEMENTS

Details of Associated Provisional Application Nos: Australian Provisional Application No. PQ6045 Filed: 6 t March, 2000 The following statement is a full description of this invention, including the best method of performing it known to us: -1- 2001-03-06,A \32&crlmin.compfie2..pdl -la- TITLE: ANCHOR ELEMENTS AND METHODS AND APPARATUS FOR FABRICATING ANCHOR ELEMENTS FIELD OF THE INVENTION This invention relates to screw-in ground anchors.

2001-03-OA:U20scrwincomnplct. pd, I -2- BACKGROUND OF THE INVENTION Screw-in ground anchors have been known for some time. These anchors generally comprise a shaft carrying one or more helical flights. Rotation of the shaft of such an anchor causes the anchor to screw into the ground. Typical descriptions of such anchors include the following patent documents:- United States Patents 3,011,597 and 3,011,598 to Samual R. Galloway and William H. Galloway, published 5 December, 1961. This specification relates to a supporting post. It discloses an open-ended tube carrying one screw thread.

British Patent 1,098,555 to Trefileries Leon Bekaert published January, 1968. This specification relates to a post suitable for use as a fence-post.

It discloses an open-ended tube carrying one or more screw threads. When multiple screw threads are provided, they may form a multi-start screw thread.

Hereto, screw-in ground anchors have been used either as tension anchors or as foundation anchors.

20 For example, the A.B. Chance Company subsidiary of Emerson Electric Co. (Centralia, Missouri, USA) has for some years manufactured screw-in tension anchors for anchoring guy-wires of electrical reticulation poles and radio transmission towers.

The A.B. Chance Company has also manufactured screw-in foundation anchors for some years. Forms of these anchors specifically designed for street lighting generally comprise a hollow steel pipe, carrying at least one helical flight or auger adjacent one end.

Rotation of the pipe screws the foundation into the ground. The leading end of the pipe may be open, or it may be closed off with a shaped blanking plate. The other end of the pipe generally carries a plate to which a street light may be bolted. Some other forms of screw-in foundation anchors produced by the A.B. Chance Company are illustrated in United States Patent 4,339,899.

Our co-pending International Patent Application PCT/AU98/00606 discloses an 2001 -0-05.A:\320screwin. complee.wpd2 -3alternative use of screw-in ground anchors in which the anchor element is normally neither in tension nor in compression. That application discloses the use of screw-in ground anchors as ground reinforcement or stabilisation. The anchors are installed in earth structures, and are not normally loaded unless ground slippage starts to occur. At the point of ground slippage, interaction between the ground and the anchor tends to stabilise the ground. The loading on the shaft of the anchor at that time is tension loading along the length of the shaft.

Presently known types of screw-in ground anchors are not ideal under all conditions. For example, when screw-in ground anchors are used as foundations, they tend to be manufactured completely of steel. In a particular environment, steel may not be ideal because of the corrosive nature of the environment or because a cheaper alternative would be more suitable. This invention accordingly seeks to provide alternatives to an all-steel construction of ground anchors.

The present invention also seeks to provide methods of installing ground anchors.

1" The present invention also seeks to provide apparatus for installing foundations.

20 SUMMARY OF THE INVENTION This invention provides an anchor element comprising a screw-in ground anchor •according to the prior art, the hollow interior of which contains grout or concrete.

This invention also provides an anchor element comprising a column of grout, which element has been fabricated by using a screw-in ground anchor according to the prior art.

"This invention also provides a method of fabricating an anchor element, which method includes the installation of a screw-in ground anchor according to the prior art, and pumping grout or concrete into the hollow interior of the ground anchor.

This invention also provides apparatus for the fabrication of an anchor element, which apparatus includes means for driving a screw-in ground anchor into the ground, in 2001-03-05,:A\320scrcwin.comnpictewpd3 combination with means for pumping grout into the hollow interior of the ground anchor.

It is preferred that the diameter of the flights of the anchor element be in the range of two to three times the diameter of the shaft of the anchor element. It has been found that it is convenient for the dimensions of the anchor elements to be in the following ranges:shaft diameter, 150mm to 300mm; flight diameter, 300mm to 600mm; flight spacing along the shaft at least 2.5 times the flight diameter; and flight pitch typically one-third the helix diameter.

Specific embodiments of anchor elements and apparatus and methods in accordance with this invention will now be described by way of non-limiting examples with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE VIEWS OF THE DRAWINGS Figure 1 is a side elevational view illustrating a screw-in foundation anchor according to the prior art.

Figure 2 is a side elevational view of one form of apparatus, partly in section, used for making a first type of anchor element according to the present invention.

Figure 3 is a side elevational view of an anchor element produced by apparatus according 25 to Figure 2.

Figure 4 is a side elevational view, partly in section, of another form of apparatus used for making a second type of anchor element according to the present invention.

Figures 5 to 10 are sectional views of apparatus for the construction of a third type of anchor element in accordance with the present invention, methods of construction of such anchor elements, and of the resulting anchor elements.

2001030.OAX32Oha ceiincomplc pd,4 Figure 11 is a cross-sectional view of another embodiment of an anchor element according to the present invention.

Figure 12 is an illustration of apparatus for the construction of anchor elements in accordance with the present invention.

Figure 13 is a cross-sectional view of an alternative form of apparatus for the construction of anchor elements in accordance with the present invention.

Figure 14 is an enlarged view of a fragment of Figure 13.

Figure 15 is an enlarged view of a fragment of Figure 13.

DETAILED DESCRIPTION WITH RESPECT TO THE DRAWINGS Prior art Figure 1 shows a screw-in foundation element 1 according to the prior art. The foundation element 1 comprises a hollow shaft 2 open at leading end 3 and at trailing end °20 4. The leading end 3 is tapered at 45 to the axis of shaft 2. The shaft carries at least one S"helical flight such as 6 adjacent its leading end, and may carry one or more helical flight such as 7 adjacent the trailing end. The shaft and flights are usually fabricated from steel.

°eooe Holes 8 pass diametrically through the shaft 2 adjacent the trailing end 4 for coupling of a drive tool such as is illustrated in United States Patent 5,011,336 Chance Company). Rotation of the drive tool screws foundation element 1 into the ground.

Apparatus and methods according to the present invention Figure 2 shows apparatus, partly in section, used for making a first type of screw-in anchor element according to the present invention. This figure shows an anchor element 11 with a single flight 12. The flight 12 is not welded to a shaft, but instead it is welded to a pilot section 13 which in turn is detachably connected to a drive tool 14 in the form of a shaft having a hollow interior 15. A tie rod 16 integral with a plug 17 runs down the 200) .3-05.A:320screwincomplete.wp -6hollow shaft of the drive tool 14.

The anchor element 11 is screwed into the soil in the usual manner. Plug 17 prevents the leading end of the anchor from being occluded with soil as the anchor is advancing into the ground. When the anchor has reached the desired depth, the tie rod 16 and plug 17 are removed. The hollow interior 15 of drive tool 14 is then pumped full of grout, and the drive tool is disengaged from the pilot section 13 and removed from the ground. In this specification "grout" includes fluent hardenable mixes routinely used in this field, namely masonry type mixes such as concrete and their mineral analogues and organic polymeric mixes such as epoxy compounds with delayed release hardeners. As the drive tool 14 is removed from the ground, hydrostatic pressure of the grout supports the ground and prevents it collapsing inwardly.

As shown in Figure 3, the resultant structure comprises pilot section 13 with flight 12, adhered to a grout column 18.

As an alternative to removing the tie rod 16 and plug 17 when the anchor 11 has been screwed down to the desired depth, the tie rod 16 may be left in place, to form a reinforcing element running the length of the anchor.

S•As yet further alternatives (not illustrated in the drawings) the tie-rod 16 and plug 17 may be removed, and other reinforcement inserted. This other reinforcement may be inserted either before or after the hollow interior 15 of the drive tool 14 is pumped full of grout.

25 A yet further alternative illustrated in Figure 4 is particularly suitable where the anchor element is to be used as a ground reinforcement in accordance with our co-pending International Patent Application PCT/AU98/00606. According to this embodiment, an anchor 20 has a pilot section 21 carrying a flight 22 attached to a hollow drive tool 23.

A high-tensile strength pultruded plastics reinforcement element 24 is attached to the pilot section 21 and extends the length of the drive tool 23. When anchor 20 has been installed to the desired depth, grouting is pumped into the interior of the hollow drive tool 23, and the drive tool is then removed. When the grouting has set, an end-plate (not illustrated) may be attached to the end 26 of the reinforcement element 24 and used to 2001-03-OSAUs20srewincomplae.wpd.6 -7pre-tension the anchor.

The methods and apparatus of further preferred embodiments of the invention are illustrated by reference to Figures 5 to These figures show a screw-in anchor 31 according to the prior art which has been screwed into the ground to the desired foundation depth. In the embodiments according to these figures, the anchor is shown as having reached underlying rock, but this need not be the case.

The hollow anchor element 31 is fitted with a plug 33 at its leading end. Preferably, the anchor element 31 has a shaft outside diameter in the vicinity of 150mm to 300mm. The plug 33 is held in place by a plug rod 32 which passes through the length of the anchor element, which in turn is held in place by a readily removable pin 34 which passes diametrically through the anchor element, utilising holes 35 in the anchor 31 and hole 36 in the rod 32.

As shown in Figure 6, the plug 33, rod 32 and pin 34 are then withdrawn, and the hollow interior of the anchor element 31 is filled with grout 36. The anchor element may then 20 be withdrawn from the soil as illustrated in Figure 7. The anchor element may be completely withdrawn from the ground. As the anchor element 31 is withdrawn from the ground, hydrostatic pressure of the grout supports the ground and prevents it collapsing inwardly. This leaves in place a column of grout 42 to serve as a foundation.

Reinforcement may be placed in the grouting either before the anchor element 31 is 25 withdrawn.

As illustrated in Figure 7, as the anchor element 31 is withdrawn from the ground, the grouting 36 will flow out of the interior of the anchor element to form a void such as 37.

Alternatively to totally withdrawing the anchor element 31 from the soil as illustrated in Figure 7, further grouting as shown at 38 in Figure 8 may be pumped into this void, and the trailing end of the anchor element 31 then plugged by a grout plug 39. Preferably, the anchor element 31 is withdrawn a distance of about 2m from the ground before the further grout 38 is pumped into the void 37. The grout plug 39 is preferably cylindrical 2001 -03-05,A:\320scrcincomplctwpd7 -8in shape, fabricated from mild steel provided with rubber seals to seal between the grout plug 39 and the internal bore of anchor element 31. The grout plug 39 is held in place by a pin 41 passing diametrically through the anchor element 31 and the grout plug 39.

As shown in Figure 9, once further grout 38 has been pumped into void 37 and the grout plug 39 fixed in place, the anchor element 31 is again screwed into the ground, preferably through a displacement of about 0.5m from the position illustrated in Figure 8. This forces the lower end of the column of grout to bulge outwardly as shown at 43 in Figure 9, increasing the effective foundation bearing area of the column of grout 42. The procedures of partly unscrewing the foundation element from the ground, placing further grouting into it, plugging its trailing end with the grout plug, and partially screwing it back into the ground can be repeated as many times as are necessary to create the required size of the mass 43.

When the mass 43 is at the required size, reinforcing bars or reinforcing cages may be placed in the column of grout 36.

.Variants of the embodiment of the present invention according to Figures 7 to 10 can be used for the purposes of the invention disclosed in our co-pending International Patent Application PCT/AU98/00606. (That application discloses the use of screw-in ground Sanchors as ground reinforcement or stabilisation). Figure 11 shows an embankment 51 which has an exposed, inclined earthen face 52. Element 53 is a reinforcement element fabricated according to a variant of the embodiments according to Figures 7 to 25 Reinforcement element 53 comprises a shaft 54 and one or more bulbous masses of grout 56 and 57. The reinforcement element 53 has been fabricated by the insertion ofa screw-in anchor element into the embankment and then pumping grouting into the hollow interior of the anchor element, analogous to Figure 6. The process as illustrated with reference to Figures 7 to 10 has then been iterated. That is, the anchor has been partially withdrawn, the resultant void filled with grout, and the anchor then partially re-inserted (that is, screwed back in, but not to the original depth of penetration) to form the bulbous mass of grout 55. This process has been reported to form the mass 56, and repeated again to form the mass 57.

2001 03-0.A:320socwinmcmpite.twpd -9- Figure 12 illustrates apparatus for the fabrication of anchor elements in accordance with the present invention. In this figure, an excavator 61 is provided with a hydraulically driven arm 62 which carries a hydraulically powered torque power head 63. A grout swivel 65 is mounted to the drive shaft of torque power head 63. A grout mixer 68 is connected to a grout pump 67 which is in turn connected via a valve 66 to grout swivel The valve 66 is operable to control the flow of grout into the grout swivel. The grout mixer 68, grout pump 67 and valve 66 may all be mounted on the excavator 61.

The grout swivel 65 is in turn connected by a detachable coupling to an anchor element 64. The grout swivel 65 is known in the art, and may be similar to the liquid element swivel disclosed in United States patent 5,374,140 (Standish et al).

Figure 13 shows another form of apparatus for making an anchor element according to the present invention. Figure 1 shows a tool 71 which has a hollow shaft 72. The shaft 72 carries a multi-turn helix 73 adjacent its leading end 74, and a grout swivel 76 adjacent its opposite end.

eeee •The tool 71 also carries a valve 77 at its leading end 74. The valve 77 includes a valve plate 79 which according to the present embodiment is frustro-conical in shape and a complementary valve seat 78 which is fixed to the shaft 72.

A valve control rod 81 access internally to the shaft 72, and protrudes through the drive eoeee Sflange 81 which closes off the trailing end 82 of the shaft 72.

e 25 In use, the tool 72 may be fitted with grout and then used to form any number of anchors as previously described. The valve 77 is operated by control rod 79 to control the flow of grouting in forming such an anchor.

Throughout this specification:the words 'comprising' and 'comprises' mean including, but not limited to, or includes, without limitation; and 2003-03-0S.A:20wewin.conplete .pd.9 any reference to a patent specification is not an admission that the contents of that specification are part of the common general knowledge of a person skilled in the art in Australia.

2001-03-O.A.\320Zscr n comple

Claims (9)

1. A method of casting an in-ground column by inserting a hollow screw-in ground anchor into the ground, closing the leading end of the anchor with a plug prior to insertion, removing the plug after insertion, filling the hollow interior of the anchor with grout, closing the trailing end of the anchor with a plug and creating a bulge in the S•column of grout beyond the leading edge of the ground anchor.

2. A method is claimed in Claim 1, wherein the bulge is created by partially S 15 unscrewing the ground anchor, admitting extra grout to the void in the anchor interior and re-screwing the anchor to force the grout to enlarge the cross-section of the column at the leading end of the anchor.

3. A method as claimed in Claim 2, wherein the operation is repeated to create two 20 or more bulges.

4. A method as claimed in any one of Claims 1-4, wherein the hollow anchor is suspended from a torque power head and coupled to a grout pump via a grout swivel.

A method as claimed in any one of Claims 1-5, wherein the anchor has a pilot section and a disengageable driver section, and the anchor is inserted in the ground, filled with grout and the drivers section is removed.

6. A method as claimed in any one of Claims 1-5, wherein reinforcement is inserted in the anchor interior before filling.

7. A method as claimed in Claim 6, wherein the reinforcement is pre-tensioned.

2005-04-13,A:320screwin.complete 'pd. I -12-

8. Apparatus for carrying out the method of Claim 1 comprising a hollow, screw-in anchor having a removable plug at the leading end and an entry at the trailing end for the admission of fluent grout to the hollow interior.

9. Apparatus as claimed in Claim 8, wherein the trailing end has a plug to confine the grout. Apparatus as claimed in Claim 9, wherein the plug is secured by a removable pin engaging an anchor transversely to the axis of the anchor. 11. Apparatus as claimed in any one of Claims 8-10, wherein the diameter of the flights of the anchor is 2-3 times the diameter of the shaft of the anchor. 12. Apparatus as claimed in any one of Claims 8-11, wherein the entry end plug is ooo* 15 opened and closed by a valve moved by a rod which allows grout to escape from the ground anchor. 13. Apparatus as claimed in Claim 12, wherein the valve is frustoconical. 14. Apparatus as claimed in any one of Claims 8 to 13, wherein the anchor has a pilot S-section carrying a helical flight and a hollow driver without a flight engages the pilot section. Apparatus constructed and adapted for use substantially as herein described with reference to Figures 1-4 or as modified by Figures 5-9 or as modified by Figures 13-15 of the drawings. 16. Columns constructed and adapted for use substantially as herein described with reference to Figure 10 or as modified by Figure 11 of the drawings. 17. Apparatus for carrying out the methods substantially as herein described with reference to Figure 12 of the drawings. 2005-04-13.A \320screc'incomplete wpd,12 13 Dated this 13 1h day of April, 2005. SANDERCOCK COWIE PATENT ATTORNEYS FOR SCREW IN TECHNOLOGIES PTY. LTD. 2005-04.I3.A.\32Oscrcincoplcte pd.13