GB2426012A

GB2426012A - Modular helical anchoring system

Info

Publication number: GB2426012A
Application number: GB0509807A
Authority: GB
Inventors: Duncan Clift Mcgregor
Original assignee: Screwfast Foundations Ltd
Current assignee: Screwfast Foundations Ltd
Priority date: 2005-05-12
Filing date: 2005-05-12
Publication date: 2006-11-15
Also published as: GB0509807D0

Abstract

The components of an anchoring system, as used in the construction industry for driving into the ground by rotation and for securing of aboveground structures there to, are connectable to each other by helically threaded joint portions (20) and corresponding socket portions (30), which may be correspondingly tapered. The components connectable in this way comprise at least two of the following: an elongate end section (27) with helical fins (26), an elongate extension (24) also with helical fins (26), an elongate plain extension (not shown), an adapter (not shown), a coupler (28), a head plate (not shown), a toothed tip (34).

Description

MODULAR HELICAL ANCHORING SYSTEM

This invention concerns helical anchors as used in the construction industry for various purposes for tensile load bearing.

Such anchors conventionally comprise elongate steel bars provided with helical fins.

They are driven into the ground by rotation and used for securing structures, including by attachment of cables to a suitable adapter at an upper end of the anchor.

As shown in Fig. 1, such anchors commonly consist of two or more elongate sections 10, 12, with or without helical blades 14, which are connected end to end by a hollow socket portion 16 at the end of one fitting over the adjacent end 18 of the other and by a single bolt (not shown) extending transversely through aligned apertures 15, 17 in the said socket portion 16 and the said end portion 18 received therein.

A variety of adapters, such as eye adapter 19 in Fig. 1, may be attached at the upper end of the elongate anchor or the uppermost section 10 thereof and these are connected in a similar manner by means of a single transverse bolt (not shown).

An object of the invention is to provide an improved modular helical anchoring system, specifically improved as regards the strength and reliability of the joints between elongate sections and between such sections and any adapters connected to an upper end thereof.

According to the invention the components of the anchoring system are connectable to each other by helically threaded, preferably tapering, joint portions and corresponding socket portions.

The advantage of an anchor, produced from the system of the invention over former helical anchors is that the joints are screwed together to form a continuous length of anchor shaft without any play due to bolted connections. Conventional helical anchors which use a single bolt in shear to restrain the tensile load at each joint are less strong because each bolt constitute a weak link, much weaker than the strength of each shaft alone. With the system according to the invention the shaft strength is not impaired at the joints as the threadedly engaged, tapered joining system has been demonstrated to be able to transfer tensile loads in excess of the actual shaft tensile strength.

The lack of bolted joints also means that the assembly of anchors using the system according to the invention is much faster than assembly of conventional bolted anchors.

The resulting anchor is also, now, free of axial play.

The invention will be described further by way of example with reference to the remaining accompanying drawings, in which: Fig. 2 is a schematic side view of one version of a helical extension of the system of the invention, with a rod coupler of the system shown separated at its upper end and a rock tooth point of the system shown connected to its lower end; Fig. 2a is a plan view (from below) of the rock tooth point of Fig. 2; Fig. 3 is a schematic partial side view showing one version of a helical end section of the system of the invention connected, in accordance with the invention, by a coupler, as in Fig. 2, to an extension; Fig. 4 is a schematic side view showing one size of a plain extension of the system of the invention, with a bolt coupler of the system attached to its upper end and a collared eye bolt of the system shown separated, but in a position to be attached thereto by the coupler; Fig. 5 is a schematic side view of another size of a plain extension of the system of the invention; Fig. 6 is a similar view of another size of a plain extension of the system of the invention with a head plate of the system attachable to its upper end; Fig. 6a is a plan view (from below) of the head plate of Fig. 6; Fig. 7 is a schematic side view of another version of a helical extension of the system of the invention with a drive plate adapter of the system attachable at its upper end; and Fig. 7a is a plan view (from below) of the drive plate adapter of Fig. 7.

Thus, Figs. 2 to 7 of the drawings illustrate alone or in various connectable combinations twelve different components of an exemplary modular helical anchoring system according to the present invention. Such system may also include other comparable components. The distinguishing feature is that they are all connectable by threadedly engageable tapering joint portions and corresponding socket portions.

Reinforcing bar of steel, which is conventional for production of anchors for heavy tension loading, is supplied cut to lengths, such as 500mm, 1000mm, 2000m. A typical diameter is 57mm. The ends of these cut lengths are then machined to have tapering, helically threaded joint portions 20 so as to form the plain extension pieces 21, 22, 23 showing in Figs. 4, 5 and 6. The special machine used for this thread cutting operation is portable so it could be done on site.

For production of helical extensions 24, 25, as shown in Figs. 2 and 7, helical fins 26 of appropriate dimensions are welded on at the required intervals.

Obviously, for helical end sections, such as 27 in Fig. 3, one end may be cut obliquely (as shown) or pointed, instead of having a threaded joint portion formed thereon.

Couplers 28 are provided with back to back sockets 30, each internally tapered and threaded to correspond to and inter-engage with the respective tapered joint portions 20.

These are screwed onto the ends of the extension pieces 21 - 25, and end sections 27 and used to connect them together in any suitable combination as selected for the particular site and purpose of use. The joints so formed are high strength, and far less prone to failure than the conventional bolted joints.

Other components, such as the head plate 36, shown in Figs. 616a, the drive adapter 32, shown in Figs. 7/7a and the rock tooth point 34, shown in Figs. 2/2a are similarly provided with internally tapered, threaded sockets 30 so that they can be threaded connected to the joint portions 20 of the various elongate elements 21-25, 27 in similar fashion.

The drive adapter 32 is used for attachment of a head for driving the respective anchor assembly into the ground by rotation.

The head plate 36 is a general purpose plate for attachment of other components to the embedded anchor or for embedding in concrete when used with a concrete foundation structure or pile cap.

A further coupler, namely a bolt coupler 38, is shown in Fig. 4 as have a tapered socket at one end back to back with a threaded cylindrical bore 39 at the other end, the latter being for screw threaded connection of a bolt shaft 29, which can be welded on or formed integrally upon any other attachable component. In Fig. 4 a collared eyelet component 37 is shown with such a bolt shaft 29. The eye component 37 is used for attaching cables or guys to an embedded anchor assembly for stabilising masts and the like. Many other similar components may also be included in the system by provision of suitable bolt shafts 29 or suitable threaded sockets 30.

Claims

1. A modular helical anchoring system comprising components which are connectable to each other by helically threaded joint portions and corresponding socket portions.

2. A system according to claim I wherein the joint portions and the socket portions are correspondingly tapered.

3. A system according to claim I or 2 wherein the components comprise at least two of the following: a helical end section, a helical extension, a plain extension, an adapter, a coupler, a head plate, a toothed tip.

4. A modular helical anchoring system substantially as hereinbefore described with reference to and as illustrated by any of Figs. 2 to 7 of the accompanying drawings.