AU2017200432A1 - Self Injecting Rock Bolt Assembly - Google Patents

Abstract

Abstract A rock bolt assembly 1 comprising a threaded elongate bar 3 with a tubular syringe 2 threadably attached to the front section of the bar 3. The syringe 2 contains one or more frangible cartridges 9 which contain fluid resins or grouts. The syringe 2 has one or more 5 one-way rotation paddles 12 which will allow the syringe 2 to easily rotate in one rotational direction in a borehole but will prevent or limit the extent of rotation in the opposite rotational direction. The bolt assembly 1 can be used as a self-drilling bolt by having a drill bit 5 on the leading end of the bar 3 and by rotating the bar 3 in the drilling direction. During the drilling operation, the syringe rotates with the bar 3 and the paddles 12 keep the syringe 2 10 up against a stop washer 27 at the leading end of the bar 3. Once the drilling operation is complete, rotation of the bar 3 in the opposite direction causes the syringe 2 not to rotate but to threadably move axially rearwards along the bar 3. This causes the frangible cartridges 9 in the syringe 2 to rupture and discharge resin from the syringe 2 through the outlet holes 14 into the borehole. The invention provides a complete self-contained bolting and resin or 15 grouting system without the need for separate resin cartridges or any additional external resin pumping or grouting equipment on a drilling machine and is thus suited to bolting automation. 'N' *~1 S 'N <N 'S S 4, (N >4

Description

2017200432 20 Jan 2017 5

AUSTRALIA

Patents Act 1990

Peter Andrew Gray 10

SPECIFICATION

Invention Title:

Self injecting rock bolt Assembly 20

The invention is described in the following statement: -2- 2017200432 20 Jan 2017

Self Injecting Rock Bolt Assembly

Field of the Invention

The present invention relates to a bolt assembly which contains a volume of resin or 5 grouting fluid whereby the bolt assembly can self-inject that resin or grouting fluid into a borehole. Once the bolt assembly is in a borehole, the resin or grouting fluid can be injected into the borehole by simply rotating the bolt in one direction. Rotation of the bolt in the opposite direction will not cause the resin or grouting fluid to be injected into the borehole. The invention enables a rock bolt or a self-drilling rock bolt or any other bolt or bar to be 10 fixed into a borehole without the need for a separate resin cartridge to be installed in the borehole before a bolt is inserted into that borehole, or without the need for external grout or resin pumping to be undertaken, or without the need for external high pressure water pumps to hydraulically force resin out of a hollow tubular bolt. The invention provides a complete self-contained bolting and resin or grouting system without the need for separate resin 15 cartridges or any additional external resin pumping or grouting equipment on a drilling machine and is thus suited to bolting automation.

In its basic form, the invention comprises a threaded bar, rod, hollow bar or other threaded elongate member, with a separate tubular member threadably fitted over a section of the threaded bar. The tubular member has a short section of female thread at the leading end 20 of it which engages with the male thread on the threaded bar. Immediately behind the threaded section are one or more outlet holes in the tubular member. One or more frangible plastic cartridges are fitted in the gap between the outside diameter of the threaded bar and the inside diameter of the tubular member. The frangible cartridge or cartridges contains a volume of resin or grouting fluid or fluids. A stop washer is fixed to the threaded bar in front 25 of the tubular member to prevent the tubular member from advancing forwards along the bar. A piston washer is also fixed to the threaded bar at the rear end of the tubular member that will enable the tubular member to slide over the piston washer such that the piston washer fits neatly inside the rear end of the tubular member and forms a hydraulic seal with it.

The tubular member has one or more one-way rotation paddles on its outside surface 30 such that when the tubular member is inserted into a borehole, the one-way rotational paddles will enable rotation of the tubular member in one direction in the borehole, but will prevent or limit rotation in the opposite direction. Rotation of the threaded bar in the direction where -3- 2017200432 20 Jan 2017 the tubular member is prevented from rotating by the one-way rotational paddles, causes the tubular member to threadably move axially backwards along the threaded bar in the borehole. As the tubular member moves axially backwards, the piston washer on the bar compresses the one or more frangible cartridges until they rupture causing the resin or grouting fluids to 5 be ejected from the outlet holes at the front end of the tubular member.

The resin or grouting fluid or fluids may be any suitable grouting fluids including resins, chemicals, or cementitious grouts, and may be a single fluid, or be multiple fluids, or be part A and part B of a resin which mix together causing the resin to cure and harden, or be part A and part B of one resin with particular properties, and also have part A and part B of 10 another resin with different properties.

The invention can be used with bars, bolts, solid rock bolts and with hollow selfdrilling rock bolts.

Background to the Invention

Rock bolts are used to support rock in mines and tunnels as well as in civil 15 excavations. Typically a borehole is drilled into the rock, then a rock bolt is anchored into that borehole using cement grout or resin or by using a mechanical anchor of some type.

Resin anchored rock bolts have the advantage that the resin can harden quickly, such that the rock bolt can provide its full support capacity in less than a minute after installation.

With current technology, resin is typically inserted into the borehole using a 20 frangible plastic resin cartridge which contains a mastic component and a catalyst component in two separate compartments within the cartridge. A rock bolt is then pushed into the borehole behind the cartridge by the drilling machine and rotated at the same time such that the plastic resin cartridge ruptures, releasing the two resin components which are then mixed together by the rotating rock bolt. This mixed resin is then forced to flow back down the 25 borehole around the rock bolt. The rock bolt is typically rotated for a set time such that the resin is thoroughly mixed. The advantage of this system is that the bolt is installed with resin with no secondary operations required, but the disadvantage is that it requires a separate drilling operation for the borehole and requires considerable manual handling of drill rods, drive dollies, the rock bolt and the resin cartridge and is therefore not suited to automation of 30 the installation process. It also has the disadvantage that full bolt encapsulation may not occur and very high resin pressure from the piston effect of the bolt forcing itself through the resin cartridge can cause hydro-fracturing in the borehole wall. -4- 2017200432 20 Jan 2017

Altematively, resin or cement grout can be pumped through a hollow rock bolt such that the resin or grout flows through the bolt and then flows back down around the bolt to fill the annulus space between the bolt and the borehole. The advantage of resin or grout pumping is that it ensures that the bolt is completely encapsulated even if the bolt is very 5 long. The disadvantage is that it is labour intensive operation to post grout a bolt, and is also difficult to automate.

Resin anchoring of rock bolts can also be achieved by having an internal resin cartridge inside a tubular self-drilling bolt. Typically, the tubular self-drilling bolt is drilled into the rock, and once the drilling operation is completed, the resin cartridge is ruptured and 10 the resin ejected from the bolt using high pressure water pumped into the bolt. This system has the advantage that the bolt and the resin are contained in the same assembly, but it has the disadvantage that the annulus space between the tubular self-drilling bolt and the borehole is very small, typically only 1 or 2 mm, and this causes problems when drilling into rocks with a high clay content where drill cuttings can’t be flushed from the borehole. Also this type of 15 bolt requires the use of two steel tubes, a small diameter inner tube containing the resin cartridge within a larger diameter outer tube to act as the rock bolt tensile member, and this adds to manufacturing cost. Finally, the volume of resin contained within the tubular selfdrilling rock bolt is limited, and full bolt encapsulation is often not achieved particularly in broken rock. 20 Fixing rock bolts in the roof and walls of mines and tunnels using chemical resins or cementitious grouts has proved to provide effective bolt anchoring, but there are still technical and operational problems with current technology.

There is therefore a need to have a rock bolt assembly that can overcome the problems of existing resin and grout anchored rock bolts as described below. 25 Objects of the Invention

It is the objective of the invention to provide a rock bolt assembly which overcomes many of the disadvantages with existing resin or grout anchored rock bolts.

The present invention provides a rock bolt assembly that can self-inject a volume of fluid resin or grout into a borehole to anchor that rock bolt into the borehole. 30 The present invention provides a rock bolt assembly that can self-inject a volume of fluid resin or grout into a borehole by simply rotating the rock bolt. 2017200432 20 Jan 2017 -5-

The present invention provides a rock bolt assembly that has a tubular member threadably fitted over a section of the outside of the threaded bar of the bolt assembly which contains one or more frangible cartridges that contain one or more fluid resins or grouts.

The present invention provides a rock bolt assembly that enables a rock bolt that 5 can be easily installed in a borehole with a minimum of manual handling and without additional equipment being required.

The present invention provides a rock bolt assembly that is suitable for being installed using automation.

The present invention provides a rock bolt that can be tensioned up against a rock 10 face such that a bearing plate can be forced against a rock face or against steel mesh to support the rock face.

Moreover the present invention also provides a rock bolt that can be fully encapsulated with fluid resins or grouts.

Furthermore, different embodiments of the invention can be used as solid bolts 15 and rock bolts, as hollow rock bolts and as hollow self drilling rock bolts.

Summary of the Invention

According to the present invention there may be provided a rock bolt assembly comprising a threaded bar which has a tubular member threadably fitted over a section of the threaded bar which contains one or more frangible plastic cartridges that contain one or more 20 fluid resins or grouts. The tubular member can rotate with the bar in a borehole in one rotational direction but will not rotate in a borehole in the opposite rotational direction. Rotating the bar in the direction where the tubular member does not rotate, causes the tubular member to threadably move axially backwards along the threaded bar which in turn causes the fluid resins or grouts to be ejected from the tubular member into the borehole. 25 The invention could be used with either solid or hollow threaded bars, or other bars with a threaded section approximately as long as the axial length of the tubular member. For example, solid deformed bars with a threaded section on the front end of the bar.

Description of the Drawings

In order that the invention may be more readily understood and put into practical 30 effect, reference will now be made to the accompanying drawings, in which: - -6- 2017200432 20 Jan 2017

Figure 1 is an isometric view of a tensionable, substantially flush-ended, selfdrilling, self-injecting rock bolt 1 with a tensioning sleeve 4, a hollow threaded bar 3, a tubular syringe member 2, and a drill bit 5. The hollow threaded bar 3 has an external male thread 22. The syringe 2 has one or more external one-way rotation paddles 12 on its external 5 surface, and one or more outlet holes 14 near the front end of the syringe 2, and one or more inlet filler holes 15 near its rear end. A stop washer 27 is fixed to the bar 3 and is located immediately in front of the syringe 2 a short distance behind the drill bit 5.

Figure 2 is a plan view of the leading end of the self-drilling rock bolt 1 showing the tubular syringe member 2 with one or more one-way rotational paddles 12 on its outer 10 surface and with one or more outlet holes 14 near the leading end of the syringe member 2. The syringe member 2 contains at least one frangible cartridge (not shown) which has filler tube 6 which passes through an inlet hole 15 near the rear end of the syringe 2. The frangible cartridge or cartridges (not shown in Figure 2) can be filled with any suitable fluid grout or resin through the inlet 13 of the tube 6. Figure 2 also shows that the syringe 2 is assembled on 15 the leading end of a hollow threaded bar 3 just behind a drill bit 5 of a self-drilling rock bolt 1.

Figure 3 is a sectional view of the syringe 2 assembled on the leading end of a hollow threaded bar 3 just behind a drill bit 5 of a self-drilling rock bolt 1, and also shows the location of the expanded views of the syringe 2 shown in Figures 4 and 5. Figure 3 shows 20 that the hollow bar 3 has an external thread 22 and at least one frangible cartridge 9 contained within the syringe 2. The syringe 2 may also contain an optional static mixer 10 at the leading end of the syringe 2.

Figure 4 is an expanded sectional view of the rear end of the syringe 2 assembled on a hollow bar 3 which has a central hole 7. The syringe 2 has at least one inlet filler hole 15 25 through which the frangible cartridge 9 can be filled with any suitable fluid through the inlet 13 on the tube 6. The hollow bar 3 has a piston washer 8 fixed to it such that the piston washer 8 creates a hydraulic seal against the internal surface of the syringe 2 but the syringe 2 can still move both rotationally and axially with respect to the piston washer 8.

Figure 5 is an expanded sectional view of the front end of the syringe 2 30 assembled on a hollow bar 3 with a central hole 7 and with a drill bit 5 on its leading end. The hollow bar 3 has a stop washer 27 fixed to it just behind the drill bit 5 such that the syringe 2 cannot advance any further forward than the rear face of the stop washer 27. The syringe 2 -7- 2017200432 20 Jan 2017 has an internal female threaded section 11 which is threadably engaged with the thread 22 on the hollow bar 3. Immediately behind this threaded section 11 are at least one outlet hole or holes 14 in the syringe 2. In the annulus space between the outside surface of the threaded bar 3 and the inside surface of the syringe 2 at the front end of the syringe 2 may also be located 5 an optional static mixer 10, and behind the static mixer 10 is located one or more frangible cartridges 9 (also shown in Figure 3).

Figure 6 shows an isometric view of the tubular syringe member 2 with at least one outlet hole 14 and at least one inlet hole 15. The syringe 2 also has an internal female threaded section 11 and at least one one-way rotation paddle 12 on its outer surface. 10 Figure 7 shows a plan view of the tubular syringe member 2 with the one-way rotation paddles 12 and with the outlet holes 14 and with at least one inlet hole 15.

Figure 8 shows a sectional view of the tubular syringe member 2 showing the internal female threaded section 11 and the outlet holes 14 and with at least one inlet hole 15. The syringe 2 has a substantial internal space 16 which can accommodate a threaded bar or 15 bolt (not shown) as well as one or more frangible cartridges (also not shown).

Figure 9 is a plan view of the syringe 2 showing the location of the sectional view shown in Figure 10.

Figure 10 shows a section through the syringe 2 located at the position of the inlet holes 15. Figure 10 shows that in this embodiment there are two inlet holes 15. The syringe 2 20 has a central hole 16 through which the bar or bolt can be fitted. A section of the syringe 2 has an internal female thread 11. Figure 10 also shows that in this embodiment there are four outlet holes 14 in the syringe 2. Around the outer circumference of the syringe 2 are one or more one-way rotational paddles 12. The one-way rotation paddles 12 are typically inclined at an angle away from the drilling direction such that as shown in Figure 10, the drilling 25 rotation direction would be clockwise.

Figure 11 shows a flush-ended, self-drilling, self-injecting rock bolt 1 with a bearing plate 18, a tensioning sleeve 4, a hollow threaded bar 3, a tubular syringe member 2, and a drill bit 5 installed into a borehole 26 in rock 25. Figure 11 also shows the syringe 2 in its forward position on the bar 3 just after the bolt 1 has just finished drilling the borehole 26. 30 Figure 12 shows the flush-ended, self-drilling, self-injecting rock bolt 1 after it has been drilled into a borehole 26 and after the bolt 1 has been rotated in the opposite direction to the drilling direction causing the syringe 2 to be move axially backwards along 2017200432 20 Jan 2017 -8- the bar 3 and over the piston washer 8. The piston washer 8 initially compresses the one or more frangible cartridges 9 inside the syringe 2 causing them to rupture and forcing the resin to pass through the static mixer 10 before the grouting or resin fluid contained within the cartridges 9 exits the syringe 2 and flows into the borehole 26. Figure 12 also shows that the 5 once the resin 23 in the borehole 26 has cured and hardened, the tensioning sleeve 4 can be tensioned up along the bar 3 forcing the bearing plate 18 hard up against the rock mass 25.

Figure 13 is an isometric view of a tensionable, solid, self-injecting rock bolt 24 with a nut 20 with a shear pin 21, a domed ball hemispherical washer 19, a bearing plate 18, a solid threaded bar 17 with an external male thread 22, and a tubular syringe member 2. Note 10 that in this view, the bearing plate 18 is shown partially cut away to show the nut 20 and the domed ball 19 in more detail.

Figure 14 shows a self-injecting solid rock bolt 24 with a nut 20 with a shear pin 21 into the bar 17, a domed ball 19, bearing plate 18, a solid threaded bar 17, and a tubular syringe member 2, installed into a borehole 26 in rock 25. Figure 14 shows the syringe 2 in 15 its forward position on the bar 17 just after the bolt 24 has been inserted into the pre-drilled borehole 26.

Figure 15 shows the self-injecting solid rock bolt 24 after it has been installed into the borehole 26 and after the bolt 24 has been rotated in the direction to cause the oneway rotation paddles 12 to prevent the syringe 2 from rotating in the borehole 26 causing the 20 syringe 2 to be move axially backwards along the bar 17 and rupture the one or more frangible cartridges 9 inside the syringe 2 and force the resin to pass through the static mixer 10 before the grouting or resin fluid contained within the cartridges 9 exits the syringe 2 and flows into the borehole 26. Once the resin 23 in the borehole 26 has cured and hardened, the nut 20 can be tensioned up along the bar 17 by breaking the shear pin 21 with the drilling 25 machine (not shown) and the nut 20 can threadably advance forwards forcing the domed ball 19 against the bearing plate 18 to support the rock mass 25. The shear pin 21 in the nut 20 initially enables the nut 20 to rotate the bar 17 in the direction to cause the syringe 2 to move axially backwards along the bar 17.

Detailed Description of the Preferred Embodiments 30 The invention will be described with respect to self-injecting rock bolts but is not so limited. -9- 2017200432 20 Jan 2017

The preferred embodiments of the present invention overcome the problems of: manually inserting a resin cartridge into a borehole; or the requirement to manually connect up a grouting hose to the back end of a hollow rock bolt; or the requirement to use a complex resin or grouting injection head which is both expensive and prone to clogging; or the 5 requirement to use a bolt with an internal resin cartridge which has minimal bolt annulus to clear drilling cuttings and is likely to get clogged when drilling in soft rocks; or the requirement to use an expensive drive head with a high pressure water pump in order to push resin out of a hollow rock bolt. Finally, it overcomes the problem that self-drilling rock bolts which currently contain resin internally inside a separate steel tube have, which is complexity 10 and high manufacturing costs because of the necessity to have a separate internal steel tube for the resin cartridge as well as an outer steel tube to act as the rock bolt.

The present invention overcomes these problems by having resin or grout or any other suitable fluid or fluids contained within the bolt assembly such that both the resin and the bar can be inserted into a borehole at the same time. 15 For the self-drilling embodiment of the invention shown in Figures 1,11 and 12, the rock bolt assembly 1 is typically fitted into position on a drilling boom (not shown) and the rear end of the bolt assembly 1 is fitted into a drive dolly (not shown) which in turn is fitted into the drilling chuck of the drilling machine (also not shown). The self-drilling, self-injecting rock bolt assembly 1 is drilled into the rock 25 in either left or right hand drilling 20 rotation typically using water pumped through the bolt to flush out the drill cuttings from the borehole 26. Once the bolt 1 is fully drilled into the rock 25, the drilling rotation and water flushing are stopped. The drilling machine (not shown) then rotates the bolt 1 in the opposite direction to the drilling direction which causes the one-way rotation paddles 12 on the syringe 2 to prevent the syringe 2 from rotating in the borehole 26, which in turn causes the syringe 2 25 to move axially backwards along the bar 3 over the piston washer 8 which initially compresses and pressurises the frangible cartridges 9 inside the syringe 2. As the fluid pressure inside the frangible cartridges 9 increases, they rupture causing the fluid resins or grouts to flow forwards through the static mixer 10 inside the syringe 2. The cartridges 9 are typically made from thin plastic and progressively crumple up as the piston washer 8 30 advances inside the syringe 2.

If a two-part resin contained in two separate cartridges 9, is used to anchor the bolt 1, the static mixer 10 ensures that they are thoroughly mixed together before they exit the syringe through the holes 14. If two separate resins, each with different properties, are used -10- 2017200432 20 Jan 2017 to anchor the bolt, then it may require four separate cartridges to be used inside the syringe 2. For example, it is possible to use part A and part B of a high strength resin contained in two separate cartridges at the leading end of the syringe 2, with a low strength but expanding resin contained within two other cartridges at the rear end of the syringe 2. The expanding 5 resin would also have a part A and a part B, and once the two parts of the expanding resin are mixed together, it is possible to have an expansion of up to 30 times or more of their original volume. Therefore once the two parts of the expanding resin are mixed together, the expanding resin will assist to force the high strength resin out of the syringe 2. The expanding resin will then force the high strength resin to the forward end of the borehole 26 and then 10 begin to flow back down the borehole to fully encapsulate the bolt 1.

Once the syringe 2 has moved backwards along the bar 3 and fully crumpled the cartridges 9, the piston washer 8 will contact the static mixer 10 and further axial movement of the syringe 2 on the bar 3 will be prevented. Further rotation of the bar 3 by the drilling machine will then cause the tensioning sleeve 4 to tension up along the bar 3. 15 A similar installation process is used to install a solid rock bolt 24 in a borehole 26, except that the bolt 24 is inserted into a pre-drilled borehole 26.

The invention also has the advantage that as the syringe 2 moves axially backwards along the bar 3 or 17, the syringe 2 is no longer surrounding and covering the threaded bar 3 or 17 at the forward end of the borehole 26 and a direct bond can then be formed by the resin 20 23 between the bar 3 or 17 and the borehole 26.

Typically the syringe 2 is made from plastic and the stop washer and the piston washer are both made from steel and are welded to the bar 3 or 17 but are not so limited.

In the preferred embodiments of the present invention show the basic principle of a self-injecting rock bolt able to inject a borehole with any suitable grouting or resin fluids. 25 In the drawings, the same numerals have been used to designate similar integers in each Figure to avoid duplication of description.

It should be noted that different embodiments of the invention could either be used with right hand drilling then use left hand rotation for resin or grout injection, or use left hand drilling then use right hand rotation for resin or grout injection. 30 The present invention provides a complete self-contained rock bolt system including a bar, bolt or any other suitable elongate reinforcing member, the resin or grout to anchor the 2017200432 20 Jan 2017 -11- said reinforcing member into a borehole, and the mechanism whereby that resin or grout can be injected into the said borehole by simple rotation of the rock bolt.

In addition, the present invention minimises the amount of manual handling required to install a resin or grout anchored rock bolt, and the invention is ideally suited to be installed 5 using full or semi-automation of the bolt installation process.

Different embodiments of the invention can be used with any elongate reinforcing member with at least a threaded section long enough to enable the syringe 2 its full length of axial movement and could be made from any suitable material including steel, high tensile steel, fibre glass or carbon fibre but is not so limited. 10 The tubular syringe 2 could also be made from any suitable material but in preferred embodiments the syringe 2 is made from plastic.

Those skilled in the art will appreciate that the invention described herein is susceptible to variations and modifications other than those specifically described. It is to be understood that the invention includes all such variations and modifications. The invention 15 also includes all of the steps, features, compositions, and compounds referred to or indicated in this specification (unless specifically excluded) individually or collectively, and any and all combinations of any two or more of said steps or features.

Throughout this specification, unless the context requires otherwise, the word “comprise”, or variations such as “comprises” or “comprising” will be understood to imply 20 the inclusion of a stated integer or group of integers, but not to the exclusion of any other integer or group of integers.

Where the specification refers to a “bar” or to a “rod” or to a “bolt” or to a “rock bolt” or to a “self-drilling rock bolt” or to a “threaded bar” or to a “hollow bar” or to a “hollow threaded bar” it is to be understood that the invention includes all such variations and 25 modifications of the above, and any other elongate reinforcing member that could be used as a rock bolt, self-drilling bolt, bolt or other reinforcing element.

Where the specification refers to a “syringe” or to a tubular member” or to a “tubular syringe member” or to a “syringe member” it is to be understood that the invention includes all such variations and modifications of the above, and any other tubular member that could 30 be to contain one or more cartridges and can be threadably attached to a threaded bar. 2017200432 20 Jan 2017 -12-

Where the specification refers to a “paddle” or to a “one-way rotation paddle” it is to be understood that the invention includes any element that can be fixed to, or be part of, a tubular syringe that would enable the syringe to rotate in one direction in a borehole but would prevent or substantially limit rotation in the opposite direction. 5 Where the specification refers to a “stop washer” it is to be understood that the invention includes all such variations and modifications of the above, and any other member or part that could be used to prevent the syringe from moving axially forwards past it on a threaded bar.

Where the specification refers to a “piston washer” it is to be understood that the 10 invention includes all such variations and modifications of the above, and any other member or part that could be used to force resin or grout out of the tubular syringe.

Where the specification refers to a “cartridge” or to a “frangible cartridge” it is to be understood that the invention includes all such variations and modifications of the above, and any other member that could be used to contain fluid resin or grout or chemicals. 15 Where the specification refers to a “grout” or to a “fluid grout” or to a “cement grout” or to a “resin” or to a “chemical resin” or to “fluid resin” it is to be understood that the invention includes all such variations and modifications of the above, and any other fluid that could be used to cure and harden in a borehole.

Where the specification refers to a “static mixer” or to a “mixer” it is to be 20 understood that the invention includes all such variations and modifications of the above, and any other device that could be used to mix two or more fluids.

Claims (12)

1. A bolt or rock bolt assembly which comprises a threaded elongate reinforcing bar and a tubular syringe member which fits over the leading section of the elongate bar whereby the tubular syringe contains one or more frangible cartridges which have fluid resin or chemicals or grout contained within them and which are located in the annulus space between the elongate bar and the tubular syringe and where the tubular syringe has an integral female threaded section at its leading end or a female threaded washer fixed to the tubular syringe at its leading end such that the tubular syringe is threadably attached to the threaded elongate bar.

2. The rock bolt assembly referred to in Claim 1 such that when the elongate bar is rotated in one direction in a borehole it will cause the tubular syringe to rotate with it but rotation of the elongate bar in the opposite direction in a borehole will cause the tubular syringe not to rotate with the elongate bar but to move axially backwards along the elongate bar.

3. The rock bolt assembly referred to in Claim 2 whereby axial movement of the tubular syringe along the elongate bar in one axial direction will cause the frangible cartridges contained within the tubular syringe to be compressed and to rupture.

4. The rock bolt assembly referred to in Claim 3 whereby once the frangible cartridges have been ruptured further axial movement of the tubular syringe along the elongate bar will cause the resin or chemicals or grout contained within the frangible cartridges to be discharged from the tubular syringe into the borehole.

5. The rock bolt assembly referred to in Claim 4 whereby the tubular syringe is positioned over the front or leading section of the elongate bar.

6. The rock bolt assembly referred to in Claim 5 whereby a stop washer is fixed close to the leading end of the elongate bar immediately in front of the tubular syringe such that it prevents the tubular syringe from advancing axially forwards past the stop washer.

7. The rock bolt assembly referred to in Claim 6 whereby a piston washer is fixed to the elongate bar at the rear end of the tubular syringe such that the tubular syringe will move axially over the piston washer but that the frangible cartridge or cartridges contained within the tubular syringe will not move axially past the piston washer but will be compressed between the piston washer and the leading end of the tubular syringe as the tubular syringe moves axially backwards along the elongate bar.

8. The rock bolt assembly referred to in Claim 7 whereby the tubular syringe has one or more one-way rotational paddles which will allow the tubular syringe to easily rotate in one rotational direction in a suitably sized borehole but will prevent or limit the extent of rotation in the opposite rotational direction.

9. The rock bolt assembly referred to in Claim 8 whereby the tubular syringe has one or more outlet holes to enable fluids contained inside the tubular syringe to easily flow out into the annulus space in the borehole once the frangible cartridges inside the tubular syringe have been ruptured.

10. The rock bolt assembly referred to in Claim 9 whereby the tubular syringe contains a static mixer at its leading end such that fluids from the ruptured cartridge or cartridges flow through the static mixer before exiting the tubular syringe through the outlet holes.

11. The rock bolt assembly referred to in Claim 1 such that the threaded elongate bar is hollow and has a drill bit on its leading end such that the rock bolt assembly can drill its own borehole.

12. The rock bolt assembly referred to in Claim 1 where the frangible cartridges contained within the tubular syringe contain two or more different fluids including mastic and catalyst components of strong resins and expanding resins.