AU2005218036A1 - Means for securing a conduit to a cable bolt - Google Patents

Description

AUSTRALIA

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RELATED ART: NAME OF APPLICANT: ACTUAL INVENTOR: ADDRESS FOR SERVICE: INVENTION TITLE: GARFORD PTY LTD NEVILLE HEDRICK LORD AND COMPANY, Patent and Trade Mark Attorneys, 4 Douro Place, West Perth, Western Australia, 6005, AUSTRALIA.

MEANS FOR SECURING A CONDUIT TO A CABLE BOLT DETAILS OF ASSOCIATED PROVISIONAL APPLICATION NUMBER: AUSTRALIAN PROVISIONAL PATENT APPLICATION NUMBER 2004905649 FILED ON 1 OCTOBER 2004 The following Statement is a full description of this invention including the best method of performing it known to me/us: c TITLE S"MEANS FOR SECURING A CONDUIT TO A CABLE BOLT" The present invention relates to a means for securing a conduit to an elongated member such as a cable bolt.

BACKGROUND OF THE INVENTION 00 oO Cable bolts are steel tendons inserted into bore holes in a rock surface to stabilise the (Ni rock surface against collapse. In hardrock mining, a portion of the tendon is grouted, and a plate is attached to the tendon adjacent to the rock surface. The tendon is then tensioned. The plate bears upon the rock surface and thereby stabilises the rock surface.

In coal mining, where any movement of the rock surface is undesirable, an end portion of the tendon disposed innermost in the bore hole is secured therein by spinning the end portion in resin. The remaining portion of the tendon disposed in the borehole is then tensioned to stabilise immediately the rock surface. The bore hole can then be grouted safely a short time later. In the meantime, the rock surface is stabilised against collapse before grouting commences or during the grout curing period.

Grout is introduced into the bore hole via a grout tube. In some cases, the grout tube is disposed alongside the cable bolt when it is inserted into the bore hole and remains in situ after the grout has cured. In other cases, a breather tube is disposed alongside the cable bolt when it is inserted into the bore hole and remains in situ after the grout has cured. In either case, it is desirable to fasten the grout tube or breather tube securely to the cable bolt, particularly when the cable bolt is spun in resin.

8 The grout tube (or the breather tube) is known to be fastened to the cable bolt by means of electrical conduit clips or by pieces of tie wire wrapped about the grout tube S(or the breather tube) and the cable bolt at spaced intervals. This can be a labour intensive exercise, particularly when additional labour is expended on filing sharp ND 5 edges from the tie wire.

0 The present invention attempts to overcome at least in part some of the 0 aforementioned disadvantages.

SUMMARY OF THE INVENTION In accordance with a first aspect of the present invention there is provided a means for securing a conduit to a cable bolt comprising an annular band of heat-shrinkable plastics material.

In accordance with a second aspect of the present invention there is provided a method of securing a conduit along a length of cable bolt comprising the steps of: a) threading an annular band of heat-shrinkable plastics material over the conduit and the cable bolt; b) applying heat to the annular band to facilitate shrinkage of the annular band around the conduit and the cable bolt until an inner surface of the annular band is contiguously disposed around a combined periphery of the conduit and the cable bolt; and c) repeating steps a) and b) with a further plurality of the annular bands of heatshrinkable plastics material disposed at spaced intervals along the length of the conduit and the cable bolt.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a view of a conduit secured to a cable bolt with a securing means in accordance with the present invention.

00 SDESCRIPTION OF THE INVENTION Referring to Figure 1 there is shown a cable bolt 10 comprising a steel tendon 12.

The tendon 12 is composed of a plurality of outer strands 14 helically wound around a centre strand 14 to form the tendon 12. There may be six outer strands 14 wound around the centre strand 14. The tendon 12 has a plurality of bulbous portions 16 spaced apart from one another along the length of the tendon 12.

The portions of the outer strands 14 in the bulbous portions 16, are spaced apart from each other around the preiphery of the bulbous portions 16 as shown. The centre strand 14 is displaced away from the centre of the tendon 12. Each bulbous portion 16 has a bulb diameter defined as the diameter of the smallest tube through which the cable bolt 10 will pass. The outer strands 14 and the centre strand 14 are all located adjacent and within the bulb periphery.

In a preferred embodiment, each bulbous portion 16 optionally houses a rigid element 20 within a cavity 18 defined by the outer strands 14 and the centre strand 14.

Preferably, the rigid element 20 is a solid sphere, such as a steel ball bearing. It is envisaged that there will be a minimal clearance of from about 1 to 5 mm between the outermost surface 22 of each rigid element 20 and the broadest part of the cavity of the respective bulbous portion 16.

A conduit 30 is longitudinally disposed adjacent to the cable bolt 10. Preferably, the conduit 30 is fastened securely to the cable bolt 10 at spaced intervals of about 100 to 1000mm with a plurality of annular bands 40 disposed around a combined periphery of the conduit 30 and the cable bolt 10. The annular bands are preferably disposed at ID 5 regularly spaced intervals.

0 The annular bands 40 are formed from heat-shrinkable plastics material.

1 Accordingly, the diameter of the annular band 40 before heat is applied to the annular 0 band 40 (pre-shrinkage) is larger than the diameter of the annular band after heat has been applied to the annular band 40 (post-shrinkage). Advantageously, the larger diameter of the pre-shrinkage annular band 40 enables it to be readily threaded over the combined periphery of the conduit 30 and the cable bolt 10, including the combined periphery of the conduit 30 and the bulbous portions 16 of the cable bolt Preferably, the diameter of the pre-shrinkage annular band 40 is from about 40 to 100 mm.

When heat is applied to the annular band 40, the annular band 40 progressively shrinks. In use, heat is applied to the annular band 40 until an inner surface of the annular band 40 is contiguous with the combined periphery of the conduit 30 and the cable bolt 10. The circumference of the post-shrinkage annular band 40 will vary according to, and closely approximate to, the combined peripheral circumference of the conduit be 30 and the cable bolt Preferably, the annular bands 40 are about 10 to 15 mm wide and about 1 to 2 mm thick.

Before the annular bands 40 are applied to the conduit 30 and the cable bolt 10, the conduit 30 may be initially secured to the cable bolt 10 with a short length of tie wire O 50 wrapped peripherally around the combined periphery of the cable bolt 10 and the conduit 30. The annular band 40 is preferably disposed in alignment with the tie wire such that the post-shrinkage annular band 40 covers an outer surface of the tie wire Cc 50, thereby forming a protective cover over any sharp edges of the tie wire 50 and rD relieving any necessity to file away any sharp edges of the tie wire 0In use, the conduit 30 may be initially secured alongside and adjacent to the cable bolt 00 I with a plurality of short lengths of tie wire 50 that are wrapped around the combined Speriphery of the cable bolt 10 and the conduit 30 at spaced intervals. A plurality of annular bands 40 of heat-shrinkage plastics material are then threaded over the combined periphery of the cable bolt 10 and the conduit 30 and aligned with the tie wires Heat is then applied to the annular bands 40 by administration of hot air thereto with a hot air gun or a heating element until inner surfaces of the annular bands 40 are contiguous with the combined periphery of the conduit 30 and the cable bolt The cable bolt 10 is inserted into a bore hole drilled in a rock face. Typically, a resin sausage is inserted into the bore hole in known manner before insertion of the cable bolt The resin sausage is pierced by the cable bolt and the resin therein is released. An end portion of the cable bolt 10 disposed innermost in the bore hole is secured therein by spinning the end portion in the released resin. The resin is allowed to move to form a resin dam at the innermost end of the bore hole.. The remaining portion of the cable bolt 10 disposed in the borehole is then tensioned against a plate to stabilise immediately the rock surface.

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When the cable bolt 10 is tensioned or stressed, the load placed on a bulbous portion 16 will be resisted by the rigid element 20 housed within the bulbous portion 16, thereby preventing the bulbous portion 16 from collapsing.

The borehole is then filled with grout which is allowed to cure and solidify. The NO 5 grout may be introduced via the conduit 30, in which case the conduit is known as a 00 grout tube. Alternatively, the grout may be introduced by a further conduit which is progressively removed as grouting takes place, and the conduit 30 behaves as a Sbreather tube for egress of air from the borehole while it is filled with grout. The cable bolt 10 becomes thereby firmly embedded in the grout.

In the present invention, it is to be understood that the term "cable bolt" is of general applicability and covers such items as rock bolts and rock anchors and the like.

Modifications and variations as would be apparent to a skilled addressee are deemed to be within the scope of the present invention

Claims (9)

1. A means for securing a conduit to a cable bolt comprising an annular band of heat-shrinkable plastics material. Io

2. A method of securing a conduit along a length of cable bolt comprising the 00 steps of: Sa) threading an annular band of heat-shrinkable plastics material over the Sconduit and the cable bolt; b) applying heat to the annular band to facilitate shrinkage of the annular band around the conduit and the cable bolt until an inner surface of the annular band is contiguously disposed around a combined periphery of the conduit and the cable bolt; and c) repeating steps a) and b) with a further plurality of the annular bands of heat-shrinkable plastics material disposed at spaced intervals along the length of the conduit and the cable bolt.

3. A method according to claim 2, where the annular bands are disposed at regularly spaced intervals.

4. A method according to claim 2 or 3, wherein the annular bands are disposed at intervals in the range from 100 to 1000mm.

5. A method according to any one of claims 2 to 4, wherein the annular bands have an initial diameter in the range from 40 to 100mm

6. A method according to any one of claims 2 to 5, wherein the annular bands have a width of from 10 to 15 mm.

7. A method according to claim 6, wherein the annular bands have a thickness in (-i Sthe range from 1 to 2 mm.

8. A method according to any one of claims 2 to 7, wherein the conduit is initially secured to the conduit by means of tie wire at disposed spaced IO intervals and the annular bands are disposed in alignment with the tie wires 00 prior to shrinkage.

9. A method according to any one of the claims 2 to 8, wherein heat is applied to the annular bands by means of a hot air gun or an electric heating element. A method of securing a conduit cable to length of cable bolt substantially as hereinbefore described with reference to the accompanying drawings. DATED THIS 3 0 TH DAY OF SEPTEMBER 2005 Garford Pty Ltd By their Patent Attorneys LORD AND COMPANY PERTH, WESTERN AUSTRALIA