GB2127061A - Earth anchors - Google Patents

Abstract

An earth anchor in which a fluke 5 is driven through a tube/inserted in the ground and deflected outwardly through a hole 3 to extend outwardly therefrom has a member 7 in the tube to bear on the fluke and control its radius of curvature as it leaves the hole. The end 6 of the fluke may first be bent to the desired radius and the fluke and member 7 are then mounted in the tube so that the member constrains the fluke to retain its original radius of curvature; the member 7 being retained in position by a dimple 8. <IMAGE>

Description

SPECIFICATION Earth anchors This invention relates to anchoring devices of the kind known as "earth anchors" in which a tube which may be driven into the ground contains an anchoring element which may be driven outwardly from the tube below the ground surface.

Such anchoring devices are described in British Patents 1 599 312 and 1 604 613. In these prior arrangements a fluke bar is driven, generally by hammering, along the tube and encounters a deflecting surface which forces the fluke bar to bend and emerge from the tube sideways through a hole provided either in the tube wall or in an earth penetrating point mounted on the tube.

Because the fluke bar resists bending, the bar tends to pass through the tube close to the wall thereof adjacent the hole and emerge from the hole at an angle which is close to tangential to the outer wall of the tube. The extended fluke bar then has a relatively large radius of curvature and the part of the fluke bar near the tube, being parallel to the tube, is relatively ineffective in resisting puiling forces tending to uproot the anchor.

The present invention is intended to provide earth anchoring devices in which the radius of curvature of the anchoring element as it is driven outwardly may be adjusted and the element may be caused to extend from the side of the tube at a relatively large angle from the outer tube wall.

According to one aspect of the invention, there is provided an anchoring device comprising a hollow tube having an earth penetrating point formed integrally therewith or secured thereto, an aperture in the wall of the tube, a deflecting surface within the tube leading towards the aperture, an elongate anchoring element of deformable rigid material, such as steel or other metal, within the tube and associated with the deflecting surface to be driven towards and past the deflecting surface for deflection outwardly through the aperture, and a member within the tube bearing on the side of the anchoring element directed towards the aperture and determining the radius of curvature of the anchoring element as it is driven outwardly through the aperture the member being constrained from moving along the tube away from the deflecting surface as the anchoring element is driven.

In one possible arrangement the member comprises a sleeve within the tube surrounding the anchoring element and the inner edge of the sleeve adjacent the deflecting surface bears on the anchoring element to determine the radius of curvature The portion of the anchoring element remote from the deflecting surface may bear on either the inside wall of the tube or the inner surface of the sleeve remote from the deflecting surface. In both cases the anchoring element is constrained at three points, that is the deflecting surface, the edge of the sleeve adjacent the deflecting surface, and either the tube or the sleeve remote from the deflecting surface, so that it is compelled to assume a radius of curvature determined by the relative positions of these three points as it emerges from the aperture.

The sleeve may tend to be moved along the tube away from the aperture by the reaction of the anchoring element as it is driven and this movement may be prevented by fixing the sleeve in its required position in the tube. This may be achieved simply by forming a dimple or indent in the tube to obstruct movement of the sleeve.

In another possible arrangement the member comprises a block and an edge of the block adjacent the deflecting surface bears on the anchoring element which passes through the tube between the block and the wall of the tube opposed to the wall containing the aperture. With this arrangement the tube may be of rectangular cross-section and the anchoring element may comprise a flat plat which is bent in a direction perpendicular to its plane as it extends outwards through the aperture. The end of the plate remote from the aperture may be bent to provide a striking surface for hammering the anchoring element along the tube. In this arrangement the three bearing surfaces determining the radius of curvature of the anchoring element are the deflecting surface, the edge of the block adjacent thereto and the wall of the tube remote from the aperture.The block may be prevented from moving along the tube in the same way as the sleeve in the above-mentioned arrangement.

In yet another possible arrangement the member in the tube bearing on the anchoring element comprises a pin extending transversely through the tube. The pin may be fixed in the tube by passing it through the tube wall.

With all these arrangements more than one anchoring element may be provided, with respective deflecting surfaces and apertures in the tube which may be diametrically opposed or otherwise distributed around the periphery of the tube, and the same member in the tube may bear on all the anchoring elements to determine their radii of curvature. When two anchoring elements are provided they may be separate elments or their ends remote from the aperture may be joined together; they may generally be formed by bending a single bar of metal on itself so that the respective ends of the metal bar are driven through the apertures. In this case the anchoring elements are constrained at three points formed by the bearing surfaces of the deflecting surfaces and the member in the tube, and the connection of the elements at their end remote from the apertures.

The earth penetrating head may be made separately from the tube and secured thereto or it may be integral with the tube and formed by deformation of the tube end, for example a tribrachiate or cruciform cross-section. The aperture may be adjacent the junction of the tube and the earth-penetrating head and the deflecting surface may consist of a flap formed by cutting and inwardly bending a part of the tube wall to form the aperture. When the aperture is adjacent the join of the tube and earth-penetrating head which is formed by the deformation of the tube, the deformed head can provide a strong support for the deflecting surface.

The earth-penetrating head may be relatively long and the length below the anchoring element emergence may then give stability against lateral force applied to the anchoring device in the ground and oppose (1) the reaction to penetration of the ground by the anchoring element during installation and (2) when an extractive force is applied to the anchor, a tendency to movement away from the direction of the fluke which would otherwise assist in the downwardly bending of the fluke and aborting of the anchorage.

Earth anchor devices according to embodiments of the invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 is a cross-section of an earth anchoring device, Figure 2 shows a fluke bar used in the device of Figure 1, Figures 3 and 4 are cross-sections of other earth anchoring devices, Figures 5 to 8 show a device for attaching articles to an earth anchoring device according to Figures 1, 3 or 4.

In the embodiment shown in Figure 1 a cylindrical tube 1 of relatively thin mild steel is integral at its lower end with an earth penetrating pointed head 2 of cruciform cross-section. Above the head 2 the tube is provided with a hole 3 and an inwardly extending flap 4 formed by cutting the wall of the tube and bending the flap so formed inwardly. Flap 4 forms a supported, inwardly extending deflecting surface within the tube leading to the hole.

A fluke bar 5 forming a ground anchoring element, shown separately in Figure 2, is made of deformable rigid material, for example deformable metal such as mild steel, and comprises a bar of circular cross-section having a point bent head 6.

The fluke bar is placed within the tube as shown in Figure 1 with the head 6 within the tube, resting on the deflecting surface 4 and pointing towards the hole 3. The length of the fluke bar is less than that of the tube 1.

A steel cylindrical sleeve 7 is placed in the tube surrounding the fluke bar 5. The lower inner edge of the sleeve abuts the surface of the bent head 6 facing the hole and the inner surface of the sleeve at its upper part 10 abuts the surface of the straight part of the fluke 5 facing away from the aperture.

The wall of tube 1 is provided with an inwardly extending dimple 8 to engage the upper end of sleeve 7 to prevent the sleeve moving upwardly in the tube.

When the device is to be anchored in the ground the head 2 and tube 1 are driven into the ground by hammering the upper end of the tube 1 until the hole 3 is below the ground surface by a desired distance. A ram-rod, not shown in the drawing, may then be inserted in the open upper end of the tube 1 and hammered to drive the fluke bar 5 downwardly through tube 1 and outwardly through hole 3. During this operation the fluke bar is curved as it is deflected towards the hole by surface 4 and extends outwardly from the hole in a curve of constant radius, as shown in broken lines in Figure 1. When the fluke has been extended in this manner below the ground surface the anchoring device can only be uprooted by digging or applying a very large pulling force to the upper end of tube 1.

The radius of curvature of the extended fluke is: determined by the relative positions of the elements of the device bearing on the fluke as it is extended, that is the deflecting surface 4, the lower edge 9 of the sleeve 7 and the upper, inner surface 10 of the sleeve 7. As the fluke is extended the reaction between the fluke and sleeve at surface 9 tends to cause the sleeve to rise in the tube so that the radius of curvature of the extending fluke is increased. This effect is avoided by dimple 8 which prevents the sleeve rising in the tube.

When the anchoring device is assembled the end 6 of the fluke bar may be bent to the desired curvature before the fluke bar is placed in the tube 1. The fluke bar and sleeve may then be placed in the tube, which is not yet provided with a dimple, as shown in Figure 1. The exact vertical position of the sleeve in the tube is determined by the initial radius of curvature of end 6. When the sleeve has been confined in this position by application of dimple 8 the sleeve has the effect of forcing the fluke bar to retain the ariginal radius of curvature of end 6 as it is driven outwardly. The radius of curvature of the extended fluke may thus be controlled by suitably adjusting the initial curvature of end 6.

In this embodiment the bending forces applied to the fluke bar are exerted by the sleeve and the deflecting surface 4 and not by the wall of the tube 1. The tube may therefore be made of relatively thin metal and the weight of the anchoring device may be relatively small.

In this embodiment the head 2 is integral with tube 1 and the head and tube may be formed by deformation of the single tube of metal. The head 2 may be made of considerable length to prevent lateral displacement of the device in the ground while the fluke bar is being extended. Figure 1 shows an anchoring device with only one fluke bar but two or more similar fluke bars may be provided to extend through respective holes in the tube distributed around its periphery at the same height, ail the fluke bars passing through the sleeve 7.

The anchoring device of Figure 3 comprises an open-ended metal tube 31 of rectangular crosssection having an earth penetrating head 32 secured to one end. Head 32 is integral with a plug 33 of rectangular cross-section within the tube and plug 33 has a curved upper surface 34 which acts as a deflecting surface for deflecting the fluke bar 35 towards the hole 36. Plug 33 is secured within tube 31 by means of a pair of opposed indents formed in the tube engaging corresponding recesses 37 in the side surfaces of the plug. In this embodiment the fluke bar 35 comprises a plate of metal which is bent at its upper end to form a striking surface 38 allowing the plate to be driven downwardly and outwards through hole 36 by hammering on a ram-rod applied to surface 38.

The tube contains a rectangular metal block 39 having an edge 40 bearing on the fluke bar and prevented from moving upwardly in the tube by dimple 41.

As in the case of the embodiment of Figure 1, the tube 31 and head 32 may be hammered into the ground with fluke bar 35 in its position shown in solid lines in Figure 3, and the fluke bar may then be driven downwardly by means of a ram-rod so that it extends outwardly through the hole, as shown in broken lines. In this case the radius of curvature of the fluke bar is determined by its bearing on the deflecting surface 34, edge 40 and a point 42 on the wall of the tube remote from the hole. In Figure 3 surface 34 is shown as having the same radius of curvature as the fluke bar, but this is not essential.The radius of curvature of the fluke bar may again be adjusted by pre-setting it to the desired value and then assembling the anchoring device as shown in Figure 3, the position of block 39 being determined by the initial radius of the leading end of the fluke bar and block 39 being held in this position by dimple 41.

Figure 4 shows an earth anchoring device comprising an open-ended metal tube 51 secured at its lower end to an earth penetrating head 52 integral with a plug 53 in the tube which provides a pair of deflecting surfaces 54 adjacent opposed holes 55 in the wall of the tube. A pair of fluke bars 56 have earth penetrating ends 57 pointed and curved as shown so that when they are driven downwardly by means of a ram-rod they are forced outwardly through respective holes 55. A pin 58 is let into the tube 51 in such a position that it is between the fluke bars and bears on the surface of both fluke bars directed towards the respective hole through which that fluke bar extends. The fluke bars 56 may be separate members, or, as shown in broken lines, they may be joined together at their upper ends and formed from a single bar.

In this embodiment the radius of curvature of the fluke bars is determined by the relative positions of the deflecting surfaces 54, the pin 58 which bears on the side surfaces of the fluke bars and the points of contact of the upper ends of the fluke bars with the wall of tube 51 (when the bars 56 are separate) or the connection of the upper ends of the bars (when they are joined to each other). When the anchor device is assembled the lower ends of the fluke bars may again be pre-bent to the desired radius, they are placed in the tube as shown and the pin 58 may then be inserted through the wall of the tube at the desired position. When the fluke bars 56 are separate members they are conveniently tied together temporarily as shown before being placed in the tube.

In all the embodiments described above the outer surface of the tube and/or the earth penetrating head may be provided with an outstanding web to support the fluke bar when it has been driving outwardly through the hole. Such a web is shown in Figure 3, in which the web comprises a plate 43 attached to the earth penetrating head having an edge 44 which comes into contact with the fluke bar as the latter is driven outwardly. The web supports the fluke bar and increases its resistance to bending stress if force is applied to remove the anchor from the ground.

In all these embodiments the fluke bar, as it is driven outwardly through the hole, is constrained to approach the hole from the middle of the tube (as in Figure 1) or from the side of the tube remote from the hole (Figures 2 and 3). The fluke bar therefore emerges from the hole at a substantial angle from the outer surface of the tube, and not tangentially to the tube surface. The effectiveness of a given length of fluke bar extending from the hole in resisting an extractive force applied to the anchor is thus increased.

The anchoring devices described above can be used for securing objects in a given position on the ground and one method of attaching objects to the anchoring device is shown in Figures 5 to 8. In this arrangement the upper end of the tube 1 (or 31 or 51) is provided with a flange 61 and before the anchoring device is driven into the ground a loop 62 of internai dimensions such that flange 61 retains it on the tube is placed around the tube.

Loop 62 is of ovoid shape so that its wider part surrounds the tube and its narrower end may receive the ends 63 of clip 64 which are splayed out so that the clip cannot easily be removed from the loop. The clip may be attached to any article, such as a park bench, which is to be secured to the earth anchor.

Claims (20)

1. An anchoring device comprising a hollow tube having an earth penetrating end formed integrally therewith or secured thereto, an aperture in the wall of the tube, a deflecting surface within the tube leading towards the aperture, an elongate anchoring element of deformable rigid material within the tube and associated with the deflecting surface to be driven towards and past the deflecting surface for deflection outwardly through the aperture, and a member within the tube bearing on the side of the anchoring element directed towards the aperture and determining the radius of curvature of the anchoring element as it is driven outwardly through the aperture, the member being constrained from moving along the tube away from the deflecting surface as the anchoring element is driven.

2. A device according to claim 1, in which said member comprises a sleeve surrounding the anchoring element in the tube and the inner edge of the sleeve adjacent the deflecting surface bears on the anchoring element to determine the radius of curvature.

3. A device according to claim 2, in which the anchoring element bears on the inner surface of the sleeve at the end of the sleeve remote from the deflecting surface.

4. A device according to claim 1, in which said member comprises a block and an edge of the block adjacent the deflecting surface bears on the anchoring element to determine its radius of curvature, the anchoring element passing through the tube between the block and the wall of the tube opposed to the wall containing the aperture.

5. A device according to claim 4, in which the tube is of rectangular cross-section, the anchoring element comprises a plate and the end of the anchoring element remote from the aperture is so formed as to provide a striking surface for driving the anchoring element through the tube.

6. A device according to claims 2, 3, 4 or 5 in which said member is constrained from moving along the tube away from the deflecting surface by an indent provided in the wall of the tube.

7. A device according to claim 1, in which said member comprises a pin extending transversely through the tube.

8. A device according to any preceding claim, in which the tube has a pair of opposed apertures and respective deflecting surfaces leading towards the apertures and a pair of anchoring elements to be deflected outwardly through the respective apertures, the anchoring elements bearing on opposite surfaces of said member.

9. A device according to claim 8, in which the anchoring elements are joined together at their ends remote from the apertures.

10. An anchoring device comprising a hollow tube having an earth penetrating end formed integrally therewith or secured thereto, an aperture in the wall of the tube, a deflecting surface within the tube leading towards the aperture, an elongate anchoring element of deformable rigid material within the tube and associated with the deflecting surface for deflection outwardly through the aperture, and a member within the tube having a surface bearing on the side of the anchoring element directed towards the aperture at a point along the tube adjacent the aperture, said member having a surface bearing on the side of the anchoring element directed away from the aperture at a point along the tube remote from the aperture, said surfaces of the member together with the deflecting surface determining the radius of curvature of the anchoring element as it is driven outwardly through the aperture.

11. A device according to claim 10, in which the member comprises a sleeve surrounding the aperture.

12. An anchoring device comprising a hollow tube having an earth penetrating end formed integrally therewith or secured thereto, an aperture in the wall of the tube, a deflecting surface within the tube leading towards the aperture, an elongate anchoring element of deformable rigid material within the tube and associated with the deflecting surface for deflection outwardly through the aperture, and a member within the tube having a surface bearing on the side of the anchoring element directed towards the aperture at a point along the tube adjacent the aperture and determining the radius of curvature of the anchoring element as it is driven outwardly through the aperture, the anchoring element passing close to the wall of the tube opposed to the aperture as it passes said member.

13. An anchoring device comprising a hollow tube having an earth penetrating end formed integrally therewith or secured thereto, a pair of apertures in opposed walls of the tube, respective deflecting surfaces within the tube leading towards the apertures, and a pair of elongate anchoring elements of deformable rigid material within the tube and associated with the respective deflecting surfaces to be driven towards and past the deflecting surfaces for deflection outwardly through the respective apertures, and a member within the tube positioned between the anchoring elements bearing on the sides of the anchoring elements directed towards their respective apertures and determining the radii of curvature of the anchoring elements as they are driven outwardly through the apertures.

14. A device according to claim 13, in which said member is a pin set in the tube.

1 5. An anchoring device according to any preceding claim, in which the deflecting surface comprises a flap extending into the tube from the edge of the aperture.

1 6. An anchoring device according to any one of claims 1 to 14, in which the earth penetrating end comprises an earth penetrating member.

secured.to the tube and the deflecting surface comprises a surface of the earth penetrating member

1 7. An anchoring device according to any preceding claim, provided with a web mounted outside the tube adjacent the aperture and towards which the anchoring element is deflected so that the deflected anchoring element is supported by the web.

1 8. An anchoring device according to any preceding claim, in which the earth penetrating end is of cruciform or tribrachiate cross-section.

1 9. An anchoring device according to any preceding claim, in which the tube is provided with an outwardly extending flange to engage a loop surrounding the tube for securing articles to the anchoring device.

20. An anchoring device substantially as hereinbefore described with reference to Figures 1 and 2 or 3 or 4 of the accompanying drawings.