GB2528292A

GB2528292A - Ground anchors

Info

Publication number: GB2528292A
Application number: GB1412643.7A
Authority: GB
Inventors: Charles Simon James Agg; Michael Hamilton Russell
Original assignee: Platipus Anchors Holdings Ltd
Current assignee: Platipus Anchors Holdings Ltd
Priority date: 2014-07-16
Filing date: 2014-07-16
Publication date: 2016-01-20
Anticipated expiration: 2034-07-16
Also published as: GB201412643D0; WO2016009209A1; GB2528292B

Abstract

A ground anchor 110 comprises a body portion 111 having a blind bore 112 for receiving a driving tool, the blind bore defining a driving direction. There are attachment means for attaching a cable or tie. The body portion defines a working surface, having the attachment means, for engaging the ground when the ground anchor is in a load-locked position. The surface has a plurality of dimples formed thereon. Also disclosed is a ground anchor in which the opposing surface may have a plurality of sloped protrusions formed thereon, each of the sloped protrusions reducing in height in the driving direction.

Description

GROUND ANCHORS

The invention relates to ground anchors of the type which are attached to cables, rods and the like, which are driven into the ground and tilted transversely of the hole by tensioning the cable.

A variety of ground anchors already exist including tubular anchors, such as those described in CB-A-1555580 and EP-A- 0208153. These anchors are driven into the ground and then rotated to a horizontal locked position. As the surface area of these anchors is not particularly large, they are not appropriate for some uses where a particular degree of strength and resistance to removal from the ground is required.

Improvements have been made to such anchors which resulted in the addition of wings to provide a greater planar or surface area to resist the anchors from being pulled from the ground once in their tilted locked position. Examples of such wing anchors are known from EP-A-0313936, US-A-4574539 and US-A-3282002. Each of these anchors has different specific features which enable the anchors either to be easily driven into the ground, to prevent its withdrawal therefrom, or to ease the ability to rotate the anchor once embedded in the ground.

EP-A-0725853 further improved anchors of the winged type in these respects, and describes a ground anchor comprising a central hollow tubular body portion extending substantially along the length of the anchcr and a pair of laterally projecting wings extending from opposing sides of the body portion, wherein the wings are bent at an angle to the horizontal plane, and a portion of an edge of each wing is bent at an angle to the plane of the wing.

In hard ground conditions wing-type anchors are not generally suitable because of the increase in the guantity of ground media to be moved. For such conditions high capacity small profile anchors, such as the original tubular anchors, are most suitable.

EP-A-0725862 describes anchors of the small profile type and describes a ground anchor comprising a body portion having a generally triangular cross-section extending substantially along its length having generally concave sides and a continuous convex lower surface from one edge of the body portion where the sides and lower surface meet to an opposite edge.

A preferred embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Fig. 1 is a plan view of a winged anchor according to the invention; Fig. 2 is a side elevation of the winged anchor of Fig. 1; Fig. 3 is an end elevation of the winged anchor of Fig. 1; Fig. 4 is an opposite end elevation of the winged anchor of Fig. 1; Fig. 5 is an underneath plan view of the winged anchor of Fig. 1; Fig. 6 is a schematic view of the winged anchor of Fig. 1 with the eye replaced by a swaged fitting; Fig. 7 is a partial schematic view of the swaged fitting of Fig. 6 with parts omitted for clarity; and FIG. 8 is a plan view of a sirail-profiie anchor according to the invention; FIG. 9 is a side elevation of the small-profile anchor of FIG. 8; FIG. 10 is a front elevation of the small-profile anchor of FIG. 8; FIG. 11 is a rear elevation of the small-profile anchor of FIG. 8; FIG. 12 is a schematic view of the small-profile anchor of FIG. 8 with the eye replaced with a swaged fitting; FIG. 13 is a partial schematic view of the swaged fitting of FIG. 12 with parts omitted for clarity; Fig. 14a-c are schematic views of the installation steps applied to an anchor; and Fig. iSa-c show views of a small-profile anchor according to the invention.

A winged anchor 10 is shown in Figures 1 to 7. The anchor 10 comprises a central substantially tubular body portion 11 having a blind bore 12 running axially thereof for receiving a driving tool. The blind bore 12 defines a driving direction in which the anchor 10 may be driven Into the ground by the driving tool.

Projecting from each side of the body portion 11 is a wing 13. These wings 13 project upwardly or downwardly at an angle to a horizontal plane through the anchor 10. At the side edges of the wings 13 are angled winglets 14 which project at an angle to the plane of the wings 13. The edges of the angled winglets 14 are provided with rounded edge beads 15. The wings 13 and winglets 14 collectively form part of a working surface for engaging the ground and applying pressure thereto when in a load-locked position, and an opposing surface opposite the working surface.

At one end of the anchor 10, i.e. the leading end as the anchor is driven into the grcund, the wings 13 meet at a flattened driving edge 16 which may be sharpened to a chisel point. The leading wing edges 17 which connect to the driving edge 16 may also be sharpened.

At an opposite end of the anchor 10, i.e. the trailing end as the anchor is driven into the ground, the trailing edges 18 of wings 13 may curve gently in an upwardly direction. At the trailing end of the anchor, the body portion 11 has a sloping nose lla.

The anchor 10 comprises means for attaching a cable or tie.

For example, above the central body portion 11 is formed an anchor keel 19 in which an anchor eye 20 is formed, to which eye 20 a cable may be attached. The high keel 19 extends from the anchor eye 20 and tapers downwardly to the driving edge 16. It may also taper in a horizonal plane to form a point adjacent the driving edge 16.

In an alternative embodiment of the invention, as shown in Figs. 6 and 7, the eye 20 is replaced with a T-shaped swaged fitting 21. The fitting 21 is inserted into a socket 22 formed in the keel 19 with the cross bar 23 of the T positioned longitudinally to the body 11. The fitting 21 can then be rotated through 900 to the position shown in Figs. 6 and 7 whereby the cross bar 23 is anchored in the socket 22 under the keel 19. The fitting 21 can then pivot in the direction of arrow C. A wedge piece may be inserted behind the cross bar 23 to prevent the fitting 21 from rotating to a position whereby it could be pulled out of the socket 22.

In use, a cable or rod is attached to the anchor eye 20 or swaged fitting 21 and a drive rod (not shown) inserted into the bore 12. The anchor 10 is then driven into the ground in a first direction, driving edge 16 first, to its installed position, by applying a force to the drive rod. Fig. 14a illustrates the installed position of an anchor. The driving edge 16 splits the ground media by way of separating the upper side and lower side and compresses the media out of the way. The combination of using the sharpened edges 17 in conjunction with the chisel point driving edge 16 enhances the ability of the anchor 10 to cut through all variety of anchoring media. The high keel 19 further enhances significantly the ability of the anchor 10 to drive straight through difficult anchoring 1T.edia.

Once at the desired depth, the drive rod is removed from the bore 12. The anchor 10 is rotated in the ground by applying a pulling force to the cable or rod thereby rotating the anchor 10 generally perpendicular to the first direction to its load-locked position (see Figs. 14b and ho) . Once the sharp nose lla of the body 11 bites the back of the hole into which the anchor 10 is driven, this forms a fulcrum for the anchor 10 to turn about. The edges of the sloped portion of the nose lla help to consolidate the turn of the anchor 10, and the wing edges 18, winglets 14 and edge bead 15 all assist in the turning of the anchor 10.

The edges 18 of the wings 13 assist in the load locking process by reducing the "load lock distance". This is the distance A-B illustrated in Fig. 14c. This is achieved as the edges 18 bite into the ground and prevent upward slippage of the anchor 10. The edges 18 also enhance the speed at which the anchor turns.

The angled winghets 14 assist in focusing the main frustrum of the soil into the surface of the anchor 10 thereby increasing its load potential. Additionally the shape and angle of the winglets 14 reduce the spill-off effect of a traditional flat winged anchor by concentrating the frustrum of the ground media within the anchor 10 itself. This reduces the mechanical edge shear effect cf the ground media frustrum under high loads significantly and increases the load potential of the anchor 10. The profile of the edge beads 15 is designed to reduce the mechanical shear of the soil at the edge of the wings 13 in high load conditions.

When the anchor 10 is in a load locked position, the angle of the wings 13 themselves increases the overall area of soil frustum by amplifying the angle of interaction, thereby creating an increased load pctential.

A small-profile anchor 110 is shown in FIGS. 8-13. The anchor 110 comprises a generally triangular or bell-shaped body 111 having an axially extending blind bore 112 for receiving a driving tool. The blind bore 112 defines a driving direction in which the anchor 110 may be driven into the ground the driving tool. When viewed from one end, the anchor 110 is seen to have a triangular bell-shaped profile for a substantial length along its working surface. The sides of the anchor body 111 are, in profile, continuously concave from an upper edge of the working surface to edges 116 where the sides and lower surface meet. The lower surface of the body 111 is continuously convex from edge to edge. The edges 116, may curve or angle slightly upwardly from the horizontal. These edges 116 may be rounded or edge beads provided. It is to be noted that the use of the terms "concave" or "convex" are intended to include not only inwardly or outwardly rounded surfaces, but also surfaces which have flat regions which may be angled to other flat regions but which overall give an impression of concavity or convexity. The sides of the anchor body 111 collectively form part of a working surface of the anchor 110 for engaging the ground when in a Toad-locked position. The Tower surface defines an opposing surface, opposite the The anchor 110 comprises means for attaching a cable or tie.

For example, the body 111 extends upwardly to form a high keel 113 in which is formed an anchor eye 114 to which a cable may be attached. The high keel 113, which starts from the anchor eye 114, tapers dcwnwardly towards a driving edge 115. The driving edge 115 may be sharpened to a chisel point. The keel 113 may also converge in the horizontal direction to form a point as it approaches the driving edge 115. The body portion 111 has a sharp tapering nose lila at an end opposite to the driving edge 115.

In an alternative embodiment of the invention, as shown in FIGS. 12 and 13, the eye 114 is replaced with a I-shaped swaged fitting 120. The fitting 120 is inserted into a socket 121 formed in the keel 113 with the cross bar 122 positioned longitudinally to the body 111. The fitting 120 can then be rotated through 190° to the position shown in FIGS. 5 and 6 whereby the T-piece 122 is anchored in the socket 121 under the keel 113. The fitting 120 can then pivot in the direction of the arrow C. In this embodiment of the invention, the working surface of the anchor extends to below the keel 113.

The small-profile anchor may be used in the same manner as the winged anchor. In use, a cable or rod is attached to the eye portion 114 or swaged fitting 120 and a driving rod is inserted into the bore 112. The anchor 110 is driven into the ground in a first direotion, driving edge 115 first to its installed position, by applying a force to the driving rod.

The driving edge 115 splits the ground media by way of separating the upper side and lower side and compresses the media out of the way. This enhances the ability of the anchor 110 to drive more quickly and easily through harder media. The high keel 113 further enhances significantly the ability of the anchor 110 to drive straight through difficult anchoring media.

Once the anchor 110 has reached its desired depth, the drive rod is removed from the bore 112. A pulling force is applied to the cable or rod which causes the anchor 110 to rotate in the ground to a load-locked position generally perpendicular to the first direction. Once the sharp nose lila of the body 111 bites the back of the hole into which the anchor 110 is driven, this forms a fulcrum for the anchor 110 to turn about. The upwardly curved edges 116 of the anchor body ill help to consolidate the turn of the anchor 110.

The triangular or bell-shaped working surface area of the anchor 110 offers a significant increase in potential load over traditional tube-style anchors whilst the anchor remains a small profile anchcr which is necessary for hard ground conditions. The shaped surface offers high load possibilities for a small surface area anchor by focusing the frustrum of soil more clearly.

The rounded edges 116 of the anchor 110 further enhance the -10 -frustum area and reduce spill-off during high loadings and therefore reduce mechanical shear.

The anchcr 110 may be made from any suitable material depending on its required used, such as iron/steel, brass and copper based alloys, alurr.inium and possibly non-metallic materials.

The ground anchors 10, 110 described above comprise a body portion 11, 111 having a blind bore 12, 112 for receiving a driving tool. The blind bore 12, 112 defines a driving direction in which the anchor 10, 110 can be driven into the ground.

The ground anchors 10, 110 each have means for attaching a cable or tie 20, 21, 114, 120.

The body portion may be considered to have a working surface on which the attachment means is located. The working surface is arranged to engage the ground when the ground anchor 10, 110 is in a load-locked position.

The opposite side of the ground anchor defines an opposing surface, which in the load-locked position faces away from the direction in which the cable or tie extends.

The working surface of the winged anchor 10 may include the surface cf the wings 13 and winglets 14 on the side of the anchor having the attachment means and the keel 19. The opposing surface includes the other side of the wings 13 and winglets 14.

-11 -The working surface of the snail-profile anchor 110 may include the sides and the keel 113 of the body 111. The opposing surface includes the lower surface.

In preferred embodiments of the invention, the working surface has a plurality of dimples formed thereon, and/or the opposing surface has a plurality of sloped protrusions formed thereon.

The working surface may have a plurality of dimples formed thereon. It has been found that the dimples can reduce the movement of soil across the working surface to reduce the spill-off of the soil and thereby increase the load potential of the anchor 10, 110. The use of dimples has been found to increase the "effective area" of the anchor, i.e. a smaller anchor with dimples has been found to resist the same load as a larger anchor without dimples. In fact, the provision of dimples has been found to increase the effective area by as much as 15%.

Preferably, the anchor has at least 100 dimples.

The following preferable features of the dimples have been found to be advantageous.

The dimples can be depressions of any concave form, but are preferably spherically-shaped, i.e. defining a portion of the surface of a sphere.

The width of each dimple is preferably at least 2mm.

-12 -For anchors 10, 110 having a length greater than 300mm the width of each dimple is preferably at least 5mm.

The depth of each dimple is preferably at least 1mm. More preferably, the dimples define a surface of a sphere with a radius of at least 1.5mm.

For anchors 10,110 having a length of at least 300mm, the depth of each dimple is preferably at least 2.5mm.

The spacing between each dimple and its nearest neighboring dimple is preferably no more than 3mm.

For anchors 10, 110 having a length of less than 300mm, the spacing between each dimple and its nearest neighboring dimple is preferably no more than 1.5mm.

It is not essential that the entire working surface is covered in dimples, but it is preferable that at least 50% of the area of the working surface has dimples.

The opposing surface may have a plurality of sloped protrusions formed thereon.

The protrusions are preferably sloped such that they reduce in height in the driving direction. In this way they do not inorease the driving force required to drive the anchor 10, into the ground in the driving direction. However, the rear end (rear with respect to the driving direction) of the -13 -protrusions protrude from the opposing surface of the anchor such that when tension is appiied to the cable or tie, the protrusions offer resistance to motion of the anchor 10, 110 in the direction opposite the driving direction thereby enhancing the speed at which the anchor turns.

The resistance provided by the protrusions can reduce the load lock distance. Therefore, when the protrusions are provided the anchor can load iock quicker and thus load lock at a lower depth (at a lower depth a greater amount of soil restrains the anchor and provides a greater holding capacity) A further advantage of the protrusions is that they have been found to move soil away from the drive rod during the installation process, limiting the amount of material that falls into the hole created by the drive phase.

Preferably, the anchor has at least 6 protrusions, and more preferably at least 8.

The protrusions may protrude from the opposing surface by a height of at least 1.5mm.

For anchors 10, 110 having a length of at least 300mm, the protrusions protrude from the opposing surface by a height of at least 2mm.

-14 -The spacing between each protrusion and its nearest neighboring protrusion Is preferably no more than 15mm.

For anchors 10, 110 having a length of at least 300mm, the spacing between each protrusion and its nearest neighboring protrusion is preferably no ff.ore than 8mm.

It is not essential that the entire working surface is covered in protrusions, but it is preferable that at least 50% of the area of the working surface has protrusions formed thereon.

A preferred small-profile anchor is shown in Figures iSa to 15c, in which the majority of the surface of the sides have dimples. As can be seen, the lower surface incorporates rows of protrusions, symmetrically arranged either side of the longitudinal axis of the anchor.

Claims

-15 -CLAIMS1. A ground anchor comprising: a body portion having a blind bore for receiving a driving tool, the blind bore defining a driving direction; and attachment means for attaching a cable or tie, wherein: the body portion defines a working surface, having the attachment means, for engaging the ground when the ground anchor is in a load-locked pcsition and an opposing surface, substantially opposite the working surface; and the working surface has a plurality of dimples formed thereon.
2. A ground anchor comprising: a body portion having a blind bore for receiving a driving tool, the blind bore defining a driving direction; and means for attaching a cable or tie, wherein: the body portion defines a working surface, having the attachment means, for engaging the ground when the ground anchor is in a load-locked position and an opposing surface, substantially opposite the working surface; and the opposing surface has a plurality of sloped protrusions formed thereon, each of the sloped protrusions reducing in height in the driving direction.
3. The ground anchor of claim 1, wherein the opposing surface has a plurality of sloped protrusions formed thereon, each of the sloped protrusions reducing in height in the driving direction.

-16 -
4. The ground anchor of claim 1 or claim 3, wherein the dimples have a depth of at least 1mm.
5. The ground anchor of claim 1 or claim 3, wherein the dimples have a depth of at least 2.5mm.
6. The ground anchor of any one of claims 1 or 3 to 5 wherein the dimples have a width of at least 2mm.
7. The ground anchor of any one of claims 1 or 3 to 6, wherein the dimples have a width of at least 5mm.
8. The ground anchor of any one of claims 1 or 3 to 7, wherein at least 50% of the working surface has dimples, each being spaced from its nearest neighboring dimple by no more than 3mm.
9. The ground anchor of any one of claims 1 or 3 to 8, wherein at least 50% of the working surface has dimples, each being spaced from its nearest neighboring dimple by no more than 1.5mm.
10. The ground anchor of any one of claims 2 to 9, wherein the protrusions protrude frorr the opposing surface by a height of at least 1.5mm.
11. The ground anchor of any one of claims 2 to 10, wherein the protrusions protrude froir the opposing surface by a height of at least 2mm.
12. The ground anchor of any one of claims 2 to 11, wherein at least 50% of the opposing surface has protrusions, each -17 -being spaced from its nearest neighboring protrusion by no more than 15mm.
13. The ground anchor of any one of claims 2 to 12, wherein at least 50% of the opposing surface has protrusions, each being spaced from its nearest neighboring protrusion by no more than 8mm.
14. The ground anchor of any preceding claim, wherein the body portion (11) has a generally triangular cross-section extending substantially along its length having generally concave sides forming at least part of the working surface and a continuous convex lower surface forming at least part of the opposing surface from one edge (16) of the body portion where the sides and lower surface meet to an opposite edge (16)
15. The anchor of claim 14 in which the edges (16) of said body portion curve or angle upwardly where the sides and lower surface meet.
16. The anchor of claim 14 cr claim 15 in which edges (16) of said body portion where the sides and lower surface meet are rounded.
17. The anchor of any one of claims 14 to 16 further comprising a driving edge (15) formed at one end of said body portion.
18. The anchor of any one of claims 14 to 17 in which the body portion extends upwardly to form a keel (13) in which is formed an anchor eye (14) -18 -
19. The anchor of any one of claims 14 to 17 in which a keel portion is formed on the body portion in which is formed a socket (21)
20. The anchor of claim 18 or claim 19 in which the keel member (13) is convergent in a horizontal and/or vertical plane from the eye portion (14) or socket to the driving edge (15)
21. The ground anchor of any one of claims 1 to 13 wherein the body portion (11) extends substantially along the length of the anchor and a pair of laterally projecting wings (13) extending from opposing sides of the body portion, wherein a first side of each wing defines at least part of the working surface and a second side of each wing, opposite the first side, defines at least part of the opposing surface.
22. The ground anchor of claim 21, wherein the wings (13) are bent at an angle to the horizontal plane, and a portion of an edge of each wing is bent at an angle to the plane of the wing.
23. The anchor of claim 21 or claim 22 in which an edge (15) of each wing is rounded.
24. The anchor of any one of claims 21 or 23 in which the wings are curved at a trailing end (18) of the anchor.
25. The anchor of any one of claims 21 to 24 further comprising a driving edge (16) at a leading end of the anchor.-19 -
26. The anchor of claim 25 in which edges (16) of the wings at the leading end of the anchor are sharpened.
27. The anchor of any one of claims 21 to 26 in which a keel member (19) is formed on the body portion, in which keel member is located an anchor eye (20)
28. The anchor of any one of claims 21 to 26 in which a keel member is formed on the body portion, in which keel member is formed a socket (22)
29. The anchor of claim 27 or claim 28 in which the keel member is convergent in a horizontal and/or vertical plane from the eye portion (20) or socket (22) to the driving edge.