WO2011057349A1

WO2011057349A1 - Cable bolt plug

Info

Publication number: WO2011057349A1
Application number: PCT/AU2010/001519
Authority: WO
Inventors: Ian Mckay
Original assignee: Mortlach Holdings Pty Ltd
Priority date: 2009-11-13
Filing date: 2010-11-12
Publication date: 2011-05-19

Abstract

Cable bolt plug (10) comprises an elongated body (16) which is configured to interference fit into the hole (12) in which the cable bolt 14 is disposed. The plug 10 is provided with a first passage (18) through which a proximal end (20) of the cable bolt extends. A second passage (22) is provided on the plug 10 and is configured to enable injection of a fluid or slurry such as grout into the hole 12 through the plug (10). A third passage (24) is provided in the plug (10), and is configured to enable gas, such as air, within hole (12) to be vented through the plug (10) to a region (26) outside of hole (12). Plug (10) is provided with a wedging mechanism (50) to create the interference fit between the plug (10) and the hole (12).

Description

CABLE BOLT PLUG

Field of the Invention The present invention relates to a cable bolt plug which may be used to plug a hole into which a cable bolt is inserted to prevent a back flow or leakage of grout injected into the hole.

Background of the Invention

Cable bolts are often used in mining and tunnelling to minimise the risk of rock bursts or rock falls from a free face of a mine or tunnel. A typical cable bolt comprises a multi-strand steel cable which is inserted into a hole drilled into a face of a mine or tunnel. One end of the cable is initially mechanically held in place near a toe of the hole using an end holding device such as cross plates or a fish hook. An opposite end of the cable extends from a collar of the hole. A breather tube is also attached to the cable bolt and extends from a location near the toe of the hole to a location outside of the collar of the hole. One end of a grout feeder pipe is attached to the cable bolt at a point a short distance inside the hole, with an opposite end of the grout feeder pipe located outside the hole for attachment to a grout pump. Cotton wad soaked in grout is packed into the collar of the hole to form a seal. The grout soaked cotton wad is allowed to set for approximately 12 hours prior to pumping grout into the hole using the previously installed grout feeder pipe. Once the hole has been filled with grout, the grout pump is disconnected from the grout feeder pipe. The feeder pipe is bent over and clamped against a portion of the cable outside of the hole to prevent a back flow of grout. The grout is left to set for at least 24 hours. After setting of the grout, the free end of the cable is passed through a plate washer and a cable grip then attached to the free end of the cable. The cable is then tensioned as required.

The present invention has been developed with a view to simplifying and reducing the time taken to apply and grout a cable bolt in a hole. Summarv of the Invention

One aspect of the invention provides a cable bolt plug comprising:

an elongated body having a portion configured to interference fit into a hole in which at least one cable bolt is disposed, the plug provided with one or more first passages through which respective proximal ends of the one or more cable bolts can extend, a second passage configured to enable injection of a fluid into the hole through the plug, and a third passage configured to enable gas within the hole to vent to a region outside of the hole through the plug.

The cable bolt plug may comprise a flow control mechanism associated with the second passage to control back flow of the fluid from the hole through the plug.

The flow control mechanism may in one embodiment comprise a valve disposed in or adjacent the second passage, the valve configured to self close to substantially prevent back flow of the fluid through the second passage.

The valve may comprise one or more flaps, the or each flap being movable between a closed position where the or each flap closes the second passage thereby substantially preventing a back flow of fluid through the second passage, and an open position where the or each flaps are displaced to allow flow of fluid through the second passage into the hole.

In an alternate embodiment the flow control mechanism comprises a stopper configured to plug the second passage. In this embodiment the flow control mechanism may comprise a tether which couples the stopper to the body. The stopper may be arranged to plug an end of the second passage nearest a toe of the hole into which the cable bolt plug is fitted. The second passage may comprise a seat for seating the stopper when the tether is pulled to thereby close the second passage. The cable bolt plug may comprise a handle attached to an end of the tether opposite the stopper, the tether extending through the second passage and wherein the handle is disposed outside of the hole.

In an alternate embodiment the stopper is arranged for insertion into an end of the second passage distant a toe of the hole.

In various embodiments an end of the tether opposite the stopper is attached to the body.

The cable bolt plug may comprise a wedging mechanism provided on the elongated body to provide the interference fit of the plug in the hole.

The wedging mechanism may comprise a portion of an outer circumferential surface of the elongated body wherein the portion of the outer circumferential surface has an outer in which is larger than an inner diameter of the hole in which the cable bolt plug is inserted.

In one embodiment the wedging mechanism comprises at least one rib protruding from an outer circumferential surface of the elongated body.

The or each rib may be provided with a surface which ramps away from the circumferential surface of the elongated body in a direction opposite a direction of insertion of the cable bolt plug into the hole.

The or each rib may extend circumferentially about the elongated body. Alternately or additionally alternate one or more of the ribs may extend longitudinally of the elongated body.

The cable bolt plug may comprise a plurality of ribs wherein the ribs have a different maximum outer diameter, and the ribs are arranged in sequence from a rib of a lowest outer diameter to a rib of maximum outer diameter in a direction opposite the direction of insertion of the cable bolt plug into the hole.

In an alternate embodiment the wedging mechanism may comprise a circumferential land formed about the elongated body, the circumferential land being ramped to increase in outer diameter in a direction of insertion of the cable bolt plug into the hole, and an O-ring seated on the land, the O-ring and the land dimensioned so that a portion of the O-ring is proud of respective portions of the outer circumferential surface of the elongated body adjacent opposite ends of the land.

The cable bolt plug may comprise a seal seated in the elongated body and configured to form a seal about the or each cable bolt passing through the first passage.

The seal may be further configured to form a substantial seal about a hose passing through said third passage.

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The seal may comprise a body made of a resilient material and provided with respective apertures through which the or each cable bolt extending through respective first passages and, a breather hose extending through the third passage; extend.

Brief Description of the Drawings

An embodiment of the present invention will now be described with reference to the accompanying drawings in which:

Figure 1 is a cross section view of a first embodiment of a cable bolt plug in accordance with the present invention;

Figure 2 is a first end view of the cable bolt plug shown in Figure 1;

Figure 3 is an opposite end view of the cable bolt plug shown in Figure 1;

Figure 4 illustrates an embodiment of a cable bolt plug fitted into a hole in which a cable bolt is installed;

Figure 5 is a cross section view of a second embodiment of a cable bolt plug in accordance with the present invention;

Figure 6 is a schematic representation of a flow control mechanism

incorporated in a further embodiment of the cable bolt plug;

Figure 7a is a schematic representation of seal incorporated in an embodiment of the cable bolt plug; Figure 7b is a section view of the seal shown in Figure 7a;

Figure 7c is an end view of the seal shown in Figure 7b; and, Figure 8 is an end view of a further embodiment of the cable bolt plug. Detailed Description of the Preferred Embodiment

Figures 1 - 3 illustrate a first embodiment of a cable bolt plug 10 in accordance with the present invention, while Figure 4 illustrates an application of the plug 10 in use plugging a hole 12 in which a cable bolt 14 is disposed. The plug 10 comprises an elongated body 16 which is configured to

interference fit into the hole 12 in which the cable bolt 14 is disposed. The plug 10 is provided with a first passage 18 through which a proximal end 20 of the cable bolt extends. A second passage 22 is provided on the plug 10 and is configured to enable injection of a fluid or slurry such as grout into the hole 12 through the plug 10. A third passage 24 is provided in the plug 10, and is configured to enable gas, such as air, within hole 12 to be vented through the plug 10 to a region 26 outside of hole 12.

Hole 12 is formed in a body of rock 28 and has a toe 30 at a distal end, and a collar 32 at a proximal end. The cable bolt 14, which does not form part of the present invention, comprises a multi strand steel cable with an end holding device 34 at a distal end for anchoring the cable bolt in hole 12 near the toe 30. A breather tube 36 is attached to the cable bolt 14 by one or more ties 38. Once cable bolt 14 and breather tube 36 have been installed in hole 12, the proximal end 20 of the cable 14 and a proximal end 40 of breather tube 36 are fed through the first passage 18 and the third passage 24 respectively from a first in hole end 42 of the plug 0 and extend from a second opposite end 44 of the plug 10 into the region 26. A grout feeder pipe 46 is inserted into the second passage 22 from the second end 44. The plug 10 is inserted into the hole 12, end 42 first. As the plug 10 forms an interference fit with the hole 12, grout injected into the hole 12 through the grout feeder pipe 46 cannot escape between the plug 10 and the hole 12.

In one embodiment, the backflow of grout through the passage 22 can be prevented by simply pinching off the grout feeder pipe 46 in a conventional and/or convenient manner. For example: bending a length of the pipe 46 onto itself and then either tying the bent portions together or onto the proximal end 20 of the cable bolt 14; or, simply tying a knot in pipe 46. However in alternate embodiments described in greater detail below, the plug 10 may be provided with a flow control mechanism which substantially prevents the back flow of grout from the hole 12 through the plug 10 when the pipe 46 is removed.

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Referring back to Figures 1 - 3, the plug 0 is formed with a radially extending flange 48 which constitutes the end 44 of the plug 10. The flange 48 has an outer diameter greater than an outer diameter of any other portion of the plug 10. When the plug 10 is inserted into a hole 12, the flange 48 is disposed outside of the hole 12 and abuts the collar 32 to limit further insertion of the plug 10 into the hole 12. The plug 10 comprises: a solid portion 49 extending from the flange 48 and terminating at an internal wall 51 ; and a hollow portion 53 extending from the wall 51 to the end 42 of the plug 10. In the present illustrated embodiment, each of the passages 18, 22 and 24 extends for the whole length of the solid portion 49 and each open at opposite ends onto the end 44 of the plug 10, and the internal wall 51. The passages 18 and 22 are illustrated as being centred along a common diameter of the plug 10; however this need not be the case. The passage 24 lies on a further diameter of the plug 10 perpendicular to the diameter on which the passages 18 and 22 are centred.

Plug 10 is provided with a wedging mechanism 50 to provide the interference fit between the plug 10 and the hole 12. In one embodiment (not illustrated) the wedging mechanism 50 ma comprise a flexible or resilient portion of the body 16 which has an outer diameter greater than an inner diameter of the hole 12. Thus when this portion is inserted into the hole an interference fit will be provided. In one example the wedging mechanism 50 comprises configuring the elongated body 16 to generally increase in outer diameter in a direction opposite a direction of insertion of the plug 10 into the hole 12. This direction coincides with the direction frorri the in hole end 42 to the end 44 of the plug 10. This can be achieved by forming an outer circumferential surface 52 of the body 16 to progressively increase in outer diameter from end 42 to end 44.

In the embodiment illustrated in Figures 1 - 3, the wedging mechanism 50 comprises one or more ribs 54 that protrude from the outer circumferential surface 52. In Figure 1 , the plug 10 is provided with five circumferential ribs 54a - 54e (hereinafter referred to in general as "ribs 54"). The ribs 54a - 54e each have a different maximum diameter with the rib 54a having the largest outer diameter, and the rib 54e having a minimum outer diameter. The ribs 54 are arranged sequentially along the elongated body 16 with a progressively increasing outer diameter in a direction opposite the direction of insertion of the plug 10 into the hole 12. Thus, the smallest outer diameter rib 54e is located closest the end 42 while the largest outer diameter rib 54a is located closest the end 44. Each of the ribs 54 is provided with a leading surface 56 which ramps away from the outer circumferential surface 52 in a direction opposite the direction of insertion of the plug 10 into the hole 12.

Plug 10, including the ribs 54, may be made from a resilient material such as natural or synthetic rubber. This provides the plug 10 and the ribs 54 with a degree of resilience and flexibility allowing radial compression of the wedging mechanism 50 when the plug 10 is inserted into the hole 12 thereby assisting in providing the interference fit.

Plug 10 shown in Figure 1 is provided with a flow control mechanism 58 that may be used to substantially prevent a backflow of grout through the plug 10 when the hose 46 is removed. The flow control mechanism 58 comprises a stopper 60 which is configured to plug the passage 22 after injection of fluid/grout into the hole 12. The flow control mechanism 58 also comprises a tether 62 which couples the stopper 60 to the plug 10. The tether 62 extends through the passage 22 and is attached at an opposite end to a handle 64 which is also in the configuration of a hemisphere. An end 66 of the passage 62 opens onto wall 51 and may be provided with a seat 68. An operator can, when pulling the pipe 46 from the plug 10, simultaneously hold and pull on the handle 64 thus pulling the stopper 60 onto the end 66 (and seat 68 if provided) thereby sealing the second passage 22. Figure 5 illustrates a second embodiment 10a of the plug. The plug 10a comprises in general the same features as the plug 10 including first, second and third passage 18, 22 and 24 respectively; an elongated body portion 16; flange 48 at end 42; and, opposite in hole end 42. A substantive difference between the plug 10a and the plug 10 is the configuration of the wedging mechanism 50a in the plug 10a. The wedging mechanism 50a comprises three wedge systems 70a, 70b and 70c (hereinafter referred to in general as "wedge system 70"). The wedging systems 70 are of the same configuration. While the plug 10a is depicted as comprising three wedging systems 70, alternate embodiments of the plug may comprise one, two or more than three wedging systems. Each wedging system 70 comprises a circumferential land 72 formed about the elongated body 16 and a corresponding O-ring 74 seated on the land 72. The land 72 ramps or slopes in a direction so that the outer diameter of the land 72 increases in a direction of insertion of the plug 10a into the hole 2. The land 72 and its corresponding O-ring 74 are dimensioned so that the O-ring 74 is proud of the circumferential surface 52 of the elongated body 16 adjacent opposite ends of the associated land 72. That is, the O-ring 74 will always extend radially beyond the outer circumferential surface 52 adjacent the land 72 irrespective of where the O-ring 74 lies on the land 72.

The diameter of the outer circumferential surface 52 of the elongated body 16 in the plug 10a increases in a direction from end 42 to end 44. As a consequence of this, and due to the wedging system 70a being closer to end 44 than the wedging system 70c, the maximum outer diameter of the wedging system 70a is greater than the maximum outer diameter of the wedging system 70c. That is, in this embodiment each land has progressively increased minimum and maximum diameters from the wedging system 70c to the wedging system 70a. When the plug 10a is inserted into a hole 12, one or more of the wedging systems 70 and more particularly their corresponding O-ring 74 will form an interference fit with the inside surface of the hole 12. The degree of

interference can be increased by application of a force which is directed to remove the plug 10a from the hole 12. Such a force may arise from the weight of the grout injected into the hole 12. This will result in the relative movement of the O-rings 74 and lands 72 where the O-rings 74 will lie on a greater diameter portion of their corresponding land 72. This increases the wedging force of the plug 10a in the hole 12. In one variation to the wedging mechanism 50a described above, the diameter of the outer circumference 52 can be kept constant and each O-ring 74 can have the same inner diameter and outer diameter, with the interference fit arising from the O-rings 74, when seated on a portion of it's corresponding land, having their outer diameter being greater than the inner diameter of the hole 12. For any particular application if there is not sufficient interference in the fit, one or more the O-rings can be replaced with thicker O-rings, (i.e. O-rings with the same inner diameter as the original O-rings, but a larger outer diameter) In a further variation of the mechanism 50a, the diameter of the outer circumference 52 can be kept constant, each land 72 has the same

configuration (same minimum and maximum diameter and axial length) but the O-rings 74 can be formed to have the same inner diameter but progressively increased outer diameter (i.e. increased thickness) from the wedging system 70c nearest the in hole end to the to wedging system 70a most distant the in hole end. In yet another variation of the mechanism 50a, the diameter of the outer circumference 52 can be kept constant, each O-ring 74 has the same dimension but the lands 72 can be formed to be progressively shallower from wedging system 70c to wedging system 70a. This has the effect of seating the O-rings 74 higher in the direction from end 42 to end 44.

As with the plug 10, the plug 10a may also be made from a resilient material such as natural or synthetic rubber. The plug 10a may comprise a flow control mechanism similar to the mechanism 58 described in relation to the plug 0 shown in Figure 1. However in an alternate embodiment (which may also be applied to the first embodiment) the flow control mechanism 58a may comprise a stopper 76 in the form of a bung whjch is attached by tether 62a to the flange 48 of the plug 10a. The tether 62a and bung 76 may be made integrally with the plug 10a. The bung 76 is configured for insertion into the passage 22 after withdrawal of the grout feeder pipe 46 to prevent a back flow of grout from the hole 12 back through the plug 0a. Of course the embodiment of the plug 10 may incorporate the flow control mechanism 58a in place of the illustrated flow control mechanism 58.

In yet a further variation for any embodiment of the plug 10, the flow control mechanism 58 may take the form of a valve 80. Figure 6 depicts one possible configuration of valve 80 that may be used to control the flow of fluid such as grout through the passage 22. Valve 80 comprises a pair of resilient flaps 82 that extend across the passage 22 near the end 66 of the passage 22. Flaps 82 are biased to be in a normally close position as shown in Figure 6 which substantially prevents a back flow of fluid such as grout through the passage 22. Valve 80 is opened either by fluid pressure of the fluid being injected into the passage 22 or by inserting the grout feeder pipe 46 into passage 22 a - in sufficient distance to push the flaps 82 apart.

Figures 7a, 7b and 7c illustrate a seal 86 that may be incorporated in the described embodiments of the plug. The seal 86 is configured to provide a substantive seal against the flow of fluid between the cable 14 and the passage 18. In the event that there is a gap between the breather tube 36 and passage 24, the seal can also provide a substantive seal against the flow of fluid between the breather tube 36 and the passage 24. The seal 86 is in the form of a disc made from a resilient or sponge like material provided with three axially extending holes 88, 90 and 92 which register with the openings of passage 18, 22 and 24 respectively at the internal wall 51 of the plug 10. Holes 88 and 92 are of a diameter less than the diameter of the passages 18 and 24 and less than the diameter of the cable bolt 14 and breather tube 36 respectively. In this way, the seal 86 will form a substantial seal about the cable bolt 14 and breather tube 36 to prevent or minimise the back flow of fluid such as grout through the plug 10. The seal 86 may be glued onto the wall 51 in the hollow 53 of the plug 10.

Figure 8 illustrates an end view of a further embodiment 10c of the plug. The embodiment 10c is configured to accommodate two cable bolts 14 and is accordingly provided with two first passages 18a and 18b, one for each cable bolt. In all other respects the cable bolt 10c may comprise features of the earlier described embodiments. For example the plug 10c may comprise either the wedging mechanism 50 comprising the ribs 54 shown in Figure 1 or the wedging mechanism 50a comprising the lands 72 and O-ring 74 shown in Figure 6. The plug 10c may also be formed with any type of flow control mechanism 58, 58a hereinbefore described and may comprise a seal similar to seal 86 shown in Figures.7a - 7c but with the addition of a further hole to accommodate the second cable bolt.

Now that embodiments of the invention have been described in detail it will be apparent to those skilled in the relevant arts that numerous modifications and variations may be made without departing from the basic inventive concepts. For example, the flow control mechanism 58 may take alternate forms such as a ball valve disposed within the passage 22 which allows flow through the passage 22 in a direction from end 44 to end 42 but self closes to prevent a back flow of fluid in a direction from end 42 to end 44. Further, if desired a rigid sleeve may be inserted into one or more of the passages 18, 22 and 24 to maintain a substantially constant diameter and configuration to enable the passage or feeding of the cable 20, feeder hose 40 and grout feeder pipe 46. Figures 7a - 7c illustrate one form of seal 86 that may be incorporated in the plug 10 to minimise a back flow of fluid through the passages 18 and 24.

However the seal may take alternate forms to the seal depicted in these figures. For example, a resilient circumferential flange may be formed or otherwise provided about opening of the passages 18, and if required about passage 24, near the internal wall 51 of the plug 10. The flanges have an inner diameter less than that of the cable bolt 14 and the breather tube 36 to thereby form a substantial seal against the cable bolt and breather tube 36. Additionally the end of passage 22 and/or 24 which opens onto the flange 48 can be provided with a or respective markers to assist an operator in distinguishing this/these passage from passage 18 (or passages 8a, 18b) for insertion of the grout feeder pipe 46 and breather tube 36. The marker can be in the form of a countersunk blind hole or embossed mark near the opening of the passages 22 and 24 on the flange 48; or forming a countersunk rim about the openings of the passages. The latter may also assist in feeding the pipe 46/ tube 36 into the passages 22 and 24.

All such modifications and variations together with others that would be obvious to persons of ordinary skill in the art are deemed to be within the scope of the present invention the nature of which is to be determined from the above description and the appended claims.

Claims

Claims:

1. A cable bolt plug comprising:

2. The cable bolt plug according to claim 1 comprising a flow control mechanism associated with the second passage to control back flow of the fluid from the hole through the plug.

3. The cable bolt plug according to claim 2 wherein the flow control mechanism comprises a valve disposed in or adjacent the second passage, the valve configured to self close to substantially prevent back flow of the fluid through the second passage.

4. The cable bolt plug according to claim 3 wherein the valve comprises one or more flaps, the or each flap being movable between a closed position where the or each flap closes the second passage thereby substantially preventing a back flow of fluid through the second passage, and an open position where the or each flaps are displaced to allow flow of fluid through the second passage into the hole.

5. The cable bolt plug according to claim 2 wherein the flow control mechanism comprises a stopper configured to plug the second passage.

6. The cable bolt.plug according to claim 5 wherein the flow control -¹ mechanism comprises a tether which couples the stopper to the body.

7. The cable bolt plug according to claim 6 wherein the stopper is arranged to plug an end of the second passage nearest a toe of the hole into which the cable bolt plug is fitted.

8. The cable bolt plug according to claim 7 wherein the second passage comprises a seat for seating the stopper when the tether is pulled to thereby close the second passage.

9. The cable bolt plug according to claim 8 comprising a handle attached to an end of the tether opposite the stopper, the tether extending through the second passage and wherein the handle is disposed outside of the hole.

10. The cable bolt plug according to claim 5 or 6 wherein the stopper is arranged for insertion into an end of the second passage distant a toe of the hole.

11. The cable bolt plug according to any one of claims 6 to 8 and 10 wherein an end of the tether opposite the stopper is attached to the body.

12. The cable bolt plug according to any one of claims 1 to 11 comprising a wedging mechanism provided on the elongated body to provide the interference fit of the plug in the hole.

13. The cable bolt plug according to claim 12 wherein the wedging mechanism comprises a portion of an outer circumferential surface of the elongated body wherein the portion of the outer circumferential surface has an outer diameter which is larger than an inner diameter of the hole in which the cable bolt plug is inserted.

14. The cable bolt plug according to claim 12 wherein the wedging mechanism comprises at least one rib protruding from an outer circumferential surface of the elongated body.

15. The cable bolt plug according to claim 14 wherein the or each rib is provided with a surface which ramps away from the circumferential surface of the elongated body in a direction opposite a direction of insertion of the cable bolt plug into the hole.

16. The cable bolt plug according to claim 14 or .15 wherein the or each rib extends circumferentially about the elongated body.

17. The cable bolt plug according to claim 14 or 15 wherein the or each rib extends longitudinally of the elongated body.

18. The cable bolt plug according to claim 16 comprising a plurality of ribs wherein the ribs have a different maximum outer diameter, and the ribs are arranged in sequence from a rib of a smallest outer diameter to a rib of largest outer diameter in a direction opposite the direction of insertion of the cable bolt plug into the hole.

19. The cable bolt plug according to claim 12 wherein the wedging mechanism comprises at least one wedging system, each wedging system comprising a circumferential land formed about the elongated body, the circumferential land being ramped to increase in outer diameter in a direction of insertion of the cable bolt plug into the hole, and an O-ring seated on the land, the O-ring and the land dimensioned so that a portion of the O-ring is proud of respective portions of the outer circumferential surface of the elongated body adjacent opposite ends of the land.

20. The cable bolt plug according to claim 19 comprising a plurality of wedging systems spaced along the elongated body.

21. The cable bolt plug according to claim 20 wherein an outer diameter of the elongated body increase in a direction opposite a direction of insertion of the plug in the hole, and wherein each land has progressively increased minimum and maximum diameters from a wedging system nearest an in hole end of the plug to a wedging system most distant the in hole end.

22. The cable bolt plug according to claim 20 wherein an outer diameter of the elongated body is substantially constant and each O-ring has the same inner diameter and outer diameter, with the interference fit arising from the O- rings, when seated on a portion of its corresponding land, having their outer diameter being greater than the inner diameter of the hole.

23. The cable bolt plug according to claim 20 wherein an outer diameter of the elongated body is substantially constant, each land has the same configuration and the O-rings. are formed to have the same inner diameter but progressively increased outer diameter from a wedging system nearest an in hole end Of the plug to a wedging system most distant the in hole end.

24. The cable bolt plug according to claim 20 wherein an outer diameter of the elongated body is constant, each O-ring has the same dimension and the lands are formed to be progressively shallower a wedging system nearest an in hole end of the plug to a wedging system most distant the in hole end

25. The cable bolt plug according to any one of claims 1 to 24 comprising a seal seated in the elongated body and configured to form a seal about the or each cable bolt passing through the first passage.

26. The cable bolt plug according to claim 25 wherein the seal is further configured to form a substantial seal about a hose passing through said third passage.

27. The cable bolt plug according to claim 24 or 25 wherein the seal comprises a body made of a resilient material and provided with respective apertures through which the or each cable bolt extending through respective first passages and, a breather hose extending through the third passage;

extend.