WO2015189818A1

WO2015189818A1 - Combination roof bolt

Info

Publication number: WO2015189818A1
Application number: PCT/IB2015/054464
Authority: WO
Inventors: Neil Rodney ARTHUR
Original assignee: Skema Mining Components (Pty) Ltd
Priority date: 2014-06-13
Filing date: 2015-06-12
Publication date: 2015-12-17

Abstract

The invention provides a stabiliser 10 for stabilising the rock strata of the roof and/or walls of a mine tunnel, the stabiliser 10 comprising a housing 14, within which is located a substantially elongate bolt 12; characterised in that one end of the bolt terminates in an expander element 16, the expander element 16 being movable between a first position, in which at least a portion of the expander element extends from an end 15 of the housing 14, and a second position, in which the expander element 16 engages with the housing14 to expand the diameter of the housing at or near the end 15 of the housing on rotation of the bolt 12.

Description

COMBINATION ROOF BOLT

FIELD OF THE INVENTION

The invention is in the field of roof bolts, specifically roof bolts used for stabilising tunnels in mining.

BACKGROUND TO THE INVENTION

The stabilising of roofs and walls of tunnels in mines can be active, passive or combinations of both. The stabilisers used are configured to hold the strata layers of earth, which make up the walls of the tunnels, in place to avoid tunnel collapse and damage to machinery and injury to mine workers.

Active and / or passive stabilisation has previously been provided for in various ways. Active stabilisation has been achieved by using simple roof bolts which are inserted into the strata layers and having an anchor which anchors the roof bolt in place. These apparatus are generally inserted by a mine worker. The stabilising means provides and immediate support by way of a pre-load which actively resists the removal of the stabilising means from the surface of the tunnel- preventing their removal.

Passive stabilisation is provided for by using devices which only activate when pressure is applied. An increase in pressure will cause the device to work. These devices are generally used in combination with resin or cement to ensure they are secured properly in place.

The inventor believes that there is need for a device which provides a combination of both active and passive means of stabilisation thereby providing an optimum effect. SUMMARY OF THE INVENTION

For purposes of this specification conical means a structure having the shape of a cone, whether being circular, elliptical or and other shape tapering from an end towards the other end thereof.

According to an aspect of the invention there is provided a stabiliser for stabilising the rock strata of the roof and/or walls of a mine tunnel, the stabiliser comprising a housing, within which is located a substantially elongate bolt; characterised in that one end of the bolt terminates in an expander element, the expander element being movable between a first position, in which at least a portion of the expander element extends from an end of the housing, and a second position, in which the expander element engages with the housing to expand the diameter of the housing at or near the end of the housing on rotation of the bolt.

The substantially elongate bolt may be threaded along a portion of its length, alternatively the bolt may be a smooth bar, and not threaded.

The substantially elongate bolt may be kinked along its length. The kinks of the bolt may assist in absorbing any pressure on the stabiliser, in this way functioning in a manner similar to a yielding bar.

The substantially elongate bolt may comprise a hollow bar.

The substantially elongate bolt is configured to include the expander element at any point along its length. Preferably, the expander element is located at an end of the bolt. The expander element may be integral with the substantially elongate bolt or the expander element may be attachable to the bolt. The expander element may be screwed onto or forged onto the substantially elongate bolt.

The expander element may be of various shapes and may be externally threaded. In a preferred embodiment of the invention, the expander element is tapered, and may be frusto-conical in shape. The housing of the stabiliser may be substantially elongate and tubular, comprising a slit along its length, The housing may be manufactured from a suitable resiliency deformable material and may be coated in an acid resistant substance.

The material used in the manufacture of the housing is preferably a material which is capable of exerting an outward force, thereby assisting in providing a secure fit of the stabiliser relative to the strata layers of a mine tunnel. The outward pressure provides a semi-active stabilising fit relative to the strata layers.

The housing is preferably wider than a hole drilled into the strata layers, thereby providing a secure fit of the stabiliser relative to the strata layers of the mine tunnel. The hole drilled into the strata layers is generally 3mm less in diameter than the housing.

The housing is tapered at an end thereof, thereby providing for easier insertion into the drilled hole. The housing comprises various sleeves which are shaped to engage with the expander element. The sleeves may be located at any part of the housing, and typically the sleeves may be located at a point along the internal length of the housing. The sleeves may extend from the tapered end of the housing and include teeth formations which may engage the rock, to form a further securing fit with the surrounding surface, and teeth which will engage with complemental!y shaped teeth formed on the expander element. The engagement of the teeth of the sleeves and the teeth of the expander element will assist in providing a non-return effect of the expander element, and this is of specific importance upon breaking of the substantially elongate bolt when the pressure threshold has been exceeded.

The sleeves are shaped and / or threaded comp!emental!y to the shape and / or thread of the expander element and may be tapered.

In a first position, the expander element is not engaged with the sleeves, and in a second position the expander element is engaged with the sleeves. The rotation of the substantially elongate bolt causes engagement of the expander element with the sleeves.

The engagement of the expander element and the sleeves in the second position will cause the expansion of a part of the length of the housing. During expansion, the housing will expand in diameter and provide an anchor for anchoring the stabiliser to the strata layers. The housing may flare when expanded.

The stabiliser may comprise an attachment formation which assists in attaching the substantially elongate bolt to the housing.

The attachment formation may comprise a plug which receives a bolt and a nut for securing the plug in place.

The attachment formation may be of various sizes and may be forged onto the substantially elongate bolt.

The nut may include a loop, and when the stabiliser is inserted into the drilled hole, it will extend from the surface of the tunnel. This loop may be used to provide for a means of attaching each stabiliser relative to each other, thereby providing a further means of stabilisation of the strata layers, (by means of meshing and lacing), in the event of a rock fall.

The nut is threaded complementally to a thread of the substantially elongate bolt. Tightening of the nut causes the rotation of the substantially elongate bolt and thereby causes the engagement of the expander element with the sleeves, flaring the housing and thereby anchoring the stabiliser to the strata layers.

The attachment formation may be shaped to fit a drill accessory of a machine. This machine may rotate the stabiliser and thereby drilling the hole using the stabiliser as a drill bit. The machine used has a rotation function and can rotate and tighten the nut to cause rotation of the substantially elongate bolt. A cement / resin mixture may be used in conjunction with the stabiliser. BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described with reference to the following non-limiting drawings:

Figure 1 shows a side view of a stabiliser;

Figure 2 shows a further side view of the stabiliser, excluding the loop;

Figure 3 shows a side view of a substantially elongate bolt of the stabiliser;

Figure 4 shows a view of parts of the attachment means of the stabiliser;

Figure 5 shows a side view of the loop of the stabiliser;

Figure 6 shows an embodiment of the sleeve and expander element including teeth; and

Figure 7 shows a further embodiment of the sleeve and expander element including teeth.

DETAILED DESCRIPTION OF THE INVENTION

Reference numeral 10 shows a stabiliser in accordance with the invention.

Referring to figures 1 and 2, a stabiliser 10 comprises a substantially elongate bolt 12 housed within a housing 14, the stabiliser 10 further comprising an expander element 16, the housing 14 and the expander element 16 configured to expand the housing 14 upon rotation of the substantially elongate bolt 12.

The substantially elongate bolt 12 may be ribbed or smooth along its length which assists in absorbing any pressure on the stabiliser 10 and providing strength. In an embodiment of the stabiliser 10, the substantially elongate bolt 12 is kinked (this kinked version is not shown in the figures). The expander element 16 may be located at any point along the length of the substantially elongate bolt 12.

The housing 14 of the stabiliser 10 is substantially elongate and tubular, comprising a slit 18 along its length. The housing 14 is manufactured from a suitable resiliently deformable material and exerts an outward force when the substantially elongate bolt 12 is rotated causing the expander element 18 to flare the housing 14, thereby assisting in providing a secure fit of the stabiliser 10 relative to the strata layers of a mine tunnel (not shown). The outward pressure provides a semi-active stabilising fit relative to the strata layers.

The diameter of the housing 14 is wider than that of a hole drilled into the strata layers, into which the housing is to be inserted in use, thereby providing more of a secure fit of the stabiliser 10 relative to the strata layers of the mine tunnel. The hole drilled into the strata layers is generally 3mm less in diameter than the housing 14. The housing 14 is tapered 19 towards an end 15 thereof, thereby facilitating easier insertion into the drilled hole.

Referring to figures 3, 6 and 7, the housing comprises 2 or more sleeves 20 which are shaped to engage with the expander element 1 6. The sleeves 20 may be located along any part along the internal length of the housing 14, but in this embodiment of the invention the sleeves 20 are located towards an end 15 of the housing 14. The sleeves 20 are shaped and/or threaded complementally to the shape and/or thread of the expander element 16.

In one embodiment of the invention, as shown in figure 7, the sleeves 20 extend from the tapered end of the housing 14 and include teeth 50 which engage both the rock surface (not shown), to form a further securing fit with the surrounding surface, and teeth 52 which will engage with teeth 54 defined by expander element 16. The engagement of the teeth 52 of the sleeves 20 with the teeth 54 of the expander element 16 will assist in providing a non-return effect of the expander element 16, and this is of specific importance upon breaking of the substantially elongate bolt 12 when the pressure threshold has been exceeded. In this situation, at least the sleeves and the engaged expander element will likely remain in the rock face.

In a first position as shown in figure 1 , the expander element 16 is not engaged with the sleeves 20, and in a second position the expander element 16 is engaged with the sleeves 20. The rotation of the substantially elongate bolt 20 provides for engagement of the expander element 16 with the sleeves 20.

The engagement of the expander element 16 and the sleeves 20 in the second position as shown in figure 3, will cause the expansion of the diameter of the housing 14 at that point. When expanded, the housing 14 will flare and provide an anchor for anchoring the stabiliser 10 to the strata layers.

Referring to figures 1 and 2, the stabiliser 10 comprises an attachment formation 22 which assists in attaching the substantially elongate bar 12 to the housing 14. The attachment formation comprises a plug 24 which receives a bolt 26 and a nut 28 for securing the plug 24 in place.

A further nut 56 may be used which includes a loop 30 as shown in figure 1 and 5, and when the stabiliser 10 is inserted into the drilled hole, the loop 30 will extend from the surface of the tunnel. This loop 30 is used to provide for a means of attaching stabilisers 10 to one another other, thereby providing a further means of stabilisation of the strata layers, known as meshing and lacing.

The nut (28 and 56) is threaded complementally to a thread of the substantially elongate bolt 12 and tightening of the nut 28 causes the rotation of the substantially elongate bolt 12 and thereby causes the engagement of the expander element 16 relative to the sleeves 20, thereby anchoring the stabiliser 10 to the strata layers. The attachment formation 22 is shaped to fit a drill accessory of a machine. The machine used has a rotation function and can rotate and tighten the nut 28 to cause rotation of the substantially elongate bolt 12.

The invention provides for a novel stabiliser as described above.

Claims

1 . A stabiliser for stabilising the rock strata of the roof and/or walls of a mine funnel, the stabiliser comprising a housing, within which is located a substantially elongate bolt; characterised in that one end of the bolt terminates in an expander element, the expander element being movable between a first position, in which at least a portion of the expander element extends from an end of the housing, and a second position, in which the expander element engages with the housing to expand the diameter of the housing at or near the end of the housing on rotation of the bolt.

2. A stabiliser as claimed in claim 1 , characterised in that the substantially elongate bolt is threaded along a portion of its length.

3. A stabiliser as claimed in claim 1 , characterised in that the substantially elongate bolt is a smooth bar, not threaded.

4. A stabiliser as claimed in any of claims 1 to 3, charactensed in that the substantially elongate bolt is kinked along its length, to assist in absorbing pressure on the stabiliser.

5. A stabiliser as claimed in any of claims 1 to 4, charactensed in that the substantially elongate bolt comprises a hollow bar.

8. A stabiliser as claimed in any of claims 1 to 6, characterised in that the expander element is integral with the substantially elongate bolt.

7. A stabiliser as claimed in any of claims 1 to 6, charactensed in that the expander element is attachable to an end of the bolt.

8. A stabiliser as claimed in any of claims 1 to 7, characterised in that the expander element is tapered.

9. A stabiliser as claimed claim 8, characterised in that the expander element is frusto- conical in shape.

1 0. A stabiliser as claimed in any of claims 1 to 9, characterised in that the expander element is externally threaded.

1 1 . A stabiliser as claimed in any of claims 1 to 1 0, characterised in that the housing is substantially elongate and tubular and comprises a slit along its length.

1 2. A stabiliser as claimed in any of claims 1 to 1 1 , characterised in that the housing is manufactured from a resiliently deformable material, capable of exerting an outward force.

1 3. A stabiliser as claimed in any of claims 1 to 1 2, characterised in that the housing is coated in an acid resistant substance.

14. A stabiliser as claimed in any of claims 1 to 1 3, characterised in that the diameter of the housing is wider than the diameter of a hole into which the housing is inserted in use, thereby providing a secure fit of the stabiliser relative to the strata layers of the mine tunnel.

1 5. A stabiliser as claimed in claim 14 characterised in that the diameter of the hole drilled into the strata layers is 3mm less than the diameter of the housing. 8. A stabiliser as claimed in any of claims 1 to 1 5, characterised in that the housing is tapered at an end thereof. 7. A stabiliser as claimed in claim 1 6 characterised in that the stabiliser comprises at least two sleeves, located in the housing towards the tapered end of the housing and complementally shaped to engage with the expander element,.

18. A stabiliser as claimed in claim 17 characterised in that internal surface of the sleeves is complementally threaded to the external thread of the expander element.

19. A stabiliser as claimed in either of claims 17 or 18, characterised in that the sleeves extend beyond the tapered end of the housing.

20. A stabiliser as claimed in claim 19, characterised in that the sleeves include external teeth formations for engaging the rock strata, in use.

21 . A stabiliser as claimed in any of claims 17 to 20, characterised in that the sleeves include internal teeth formations for engaging with complementally shaped teeth formed on the expander element to provide a non-return effect on the expander element.

22. A stabiliser as claimed in any of claims 17 to 21 characterised in that rotation of the substantially elongate bolt moves the expander element between a first position, where it is not engaged with the sleeves, and a second position in which the expander element is engaged with the sleeves.

23. A stabiliser as claimed in claim 22 characterised in that engagement of the expander element with the sleeves in the second position causes expansion in diameter of a part of the housing at or near the end of the housing.

24. A stabiliser as claimed in claim 23 characterised in that the housing flares outwards when expanded.

25. A stabiliser as claimed in any of claims 1 to 24, characterised in that the stabiliser comprises an attachment formation for attaching the substantially elongate bolt to the housing.

26. A stabiliser as claimed in claim 25, characterised in that the attachment formation comprises a plug, securable in place by bolt and a nut.

27. A stabiliser as claimed in claim 25, characte ised in that the attachment formation is forged onto the substantially elongate bolt.

28. A stabiliser as claimed in claim 26, characterised in that the nut includes a loop, extendable from the surface of the tunnel in use.

29. A stabiliser as claimed in claim 28, characterised in that the loop provides means of attaching a number of stabilisers relative to each other.

30. A stabiliser as claimed in claim 28 characterised in that the nut is threaded complementally to a thread of the substantially elongate bolt, tightening of the nut causing rotation of the substantially elongate bolt and thereby the engagement of the expander element with the sleeves, flaring the housing and anchoring the stabiliser to the strata layers of the tunnel in use.

31 . A stabiliser as claimed in claim 25, characterised in that the attachment formation is shaped to fit a drill accessory of a machine.

32. A stabiliser as claimed in claim 31 , characterised in that the machine rotates the stabiliser to drill a hole using the stabiliser as a drill bit.

33. A stabiliser as claimed in either of claims 30 or 31 characterised in that the machine has a rotation function to rotate and tighten the nut to cause rotation of the substantially elongate bolt.

34. A stabiliser as claimed in any of claims 1 to 33 characterised in that a cement, grout or resin mixture is used in conjunction with the stabiliser for anchoring the stabiliser in the rock strata.