AU2006317519B2

AU2006317519B2 - Self drilling rock bolt

Info

Publication number: AU2006317519B2
Application number: AU2006317519A
Authority: AU
Inventors: Peter Andrew Gray
Original assignee: Individual
Current assignee: Individual
Priority date: 2005-11-24
Filing date: 2006-11-24
Publication date: 2012-11-29
Anticipated expiration: 2026-11-24
Also published as: AU2006317519A1; WO2007059580A1

Abstract

A self drilling rock bolt comprising a hollow elongate member with a drilling tip on its leading end with a nut and a domed ball on the opposite end where the nut can be rotatably advanced along a threaded section on the elongate member and with a hollow female injection sleeve fixed to the elongate member such that it prevents the nut from being unscrewed from the bar. The injection sleeve acts as a nut stop such that the nut can be used to rotate the elongate member during the drilling cycle, and also enables an injection nozzle to be inserted inside the injection sleeve so that water, resin or cement grout can be pumped into the elongate member. The injection sleeve may also contain internal seals or seals to hydraulically seal against the injection nozzle and one or more valves to control or direct the flow of fluids being pumped into the injection sleeve. The injection sleeve may also contain one or more external monitoring devices that may be connected to internal instrumentation within the elongate member. The hollow elongate member may also contain a static mixer inside its central hole in order to mix multi-component fluids pumped through it. The current invention overcomes the above problems with existing self drilling rock bolts and provides a self drilling rock bolt suited to be automatically or semi-automatically installed with a machine.

Description

WO 2007/059580 PCT/AU2006/001775 1 Self Drilling Rock Bolt Field of the Invention The present invention relates to a self drilling rock bolt and relates 5 particularly, though not exclusively, to a hollow self drilling rock bolt with an integral drilling tip, a rotational drive and tensioning system and with an integral injection sleeve with internal seals and with an internal resin mixing system that enables rock bolts to be installed and tensioned in mines and tunnels in one operation with automatic bolting and drilling machines. 10 Background to the Invention Rock bolts are now a common method to support the roof and walls of tunnels and mines worldwide. There are a wide variety of rock bolts available including steel, fibreglass and plastic rock bolts. Rock bolts usually consist of a long elongate bar which is anchored into a borehole in rock to provide reinforcement support to the rock 15 mass. Rock bolts can be anchored into a borehole by cement grout, or by resin, or by having a frictional contact with the internal surface of the borehole itself. In the case of cement grouted rock bolts, a borehole would be drilled into the rock which would have a larger diameter than the rock bolt to enable the rock bolt to be easily inserted 20 into the borehole. Cement grout would then be pumped into the annulus space between the bolt and the side walls of the borehole such that this annulus is completely filled with cement grout. This cement grout is then allowed to cure, typically for at least 8 hours, before the rock bolt is securely anchored inside the borehole. Typically, the exposed end of the rock bolt has a screw thread with a nut on 25 this thread. This nut can then be tensioned up and advanced along the rock bolt against a bearing plate to support the exposed rock face. In the case of resin anchored rock bolts, a similar borehole is drilled into the rock, but then a resin cartridge typically half the length of the rock bolt, is inserted into the borehole. This resin cartridge usually contains a polyester resin which has a 30 separate mastic component and a separate catalyst component which are isolated from each other within the cartridge by a thin plastic membrane. The resin cartridge itself is also made from a thin frangible plastic membrane, and is usually pushed up the borehole by the end of the rock bolt. Once the leading end of the resin cartridge hits WO 2007/059580 PCT/AU2006/001775 2 the end of the borehole, the rock bolt is then rotated by the drilling machine and pushed further into the borehole causing the resin cartridge to rupture, and the mastic and catalyst components of the resin are mixed together by the rotating rock bolt. The mixed resin then flows back down the annulus between the bolt and the borehole and 5 encapsulates the rock bolt. The mixed resin then cures and hardens and fully anchors the rock bolt in the borehole. Finally, a nut on a screw thread on the exposed end of the rock bolt, can then be tensioned up and advanced along the rock bolt against a bearing plate to support the exposed rock face. In the case of friction anchored rock bolts, a borehole is drilled into the rock, 10 and a rock bolt with a frictional anchoring device is inserted into this borehole. The frictional anchoring device may be one of several different devices that can be used to anchor a rock bolt by friction against the internal wall of the borehole. One common frictional anchoring device is an expansion shell mechanism which is located at the leading end of the rock bolt, and which is expanded against the wall of the borehole 15 by rotating the bolt. The expansion shell mechanism typically has a wedge which is pulled between two or more "expanding shells" by a screw thread on the end of the rock bolt such that the shells are forced outwards against the wall of the borehole. The screw thread is normally located on the leading end of the rock bolt, such that rotating the rock bolt causes the screw thread to rotate and pull the wedge between the 20 expansion shells, and force them against the sides of the borehole. Finally, an expansion shell type rock bolt may have a forged drive head on the exposed end of the rock bolt, or may have a separate nut and screw threaded section such that it could be tensioned up in a similar manner to a resin anchored rock bolt. Other types of friction anchored rock bolts include Split Set rock bolts and 25 Swellex type rock bolts. Split Set rock bolts are made from steel tubes which have a longitudinal split along their entire length. A borehole is drilled which has a smaller diameter than the spilt tube, and then the spilt tube is forced into the small hole by the drilling machine. As the drilling machine pushes the split tube into the borehole, the borehole causes the split tube to reduce in diameter such that the split tube is a tight fit 30 inside the borehole. This is turn causes the external surface of the tube to be pressed up against the walls of the borehole, thus creating a fictional anchor for the split tube. Split Set rock bolts do not have a nut on the exposed end of the bolt and cannot be tensioned up after installation.

WO 2007/059580 PCT/AU2006/001775 3 Swellex bolts are also made from tubes, but in this case they are inserted into a borehole where the borehole has a larger diameter than the Swellex bolt. The Swellex bolt is made from a steel tube where both ends of the steel tube are sealed. The tube also has a longitudinal concave indentation along its length such that the diameter of 5 the tube can be increased by inflating the tube with high pressure water. In operation, the Swellex tubular rock bolt is inserted into the borehole, and then the exposed end of the rock bolt is connected to a high pressure water pump such that the tube is filled with pressurised water and is expanded until the external surface of the tube is pressed against the wall of the borehole. This creates a frictional contact between the steel 10 tube and the rock borehole thus creating a frictional anchor for the Swellex rock bolt. Swellex rock bolts do not have a nut on the exposed end of the bolt, but instead have a round end fitting with a small external hole which is hydraulically connected to the tube such that water can be pumped through the small hole to inflate the tube. Swellex bolts cannot be tensioned up after installation. 15 Self drilling rock bolts typically consist of a hollow bar which is usually threaded along part or all of its length. A nut is then screwed on one end and a drilling tip is screwed onto the opposite end of this hollow threaded bar. The thread at the nut end of the rock bolt is also used to screw into a threaded socket on the drilling machine and this is typically used to rotate the bolt during the drilling operation. 20 During the drilling operation the bolt is rotated and water is pumped through the hollow bar to flush the rock cuttings away from the drilling tip and out of the borehole. When the borehole is drilled to its full length, the threaded socket on the drilling machine is unscrewed from the exposed end of the hollow threaded bar and a grouting hose and attachment is usually screwed onto this exposed end of the bolt. 25 Cement grout is then pumped through the grouting hose and into the bolt until the bolt and the borehole are completely filled with cement grout. The grouting attachment is then unscrewed and the grouting hose is removed. Finally, once the cement grout has cured and hardened, the nut is tightened up against a bearing plate to support the rock face. This is the typical installation procedure for existing self drilling rock bolts 30 which are used in the tunnelling industry. There are many different types of self drilling rock bolts but they all require the use of a hollow bar of some type and the use of a drilling tip of various designs. The typical drilling tips used with existing self drilling rock bolts are screwed onto the WO 2007/059580 PCT/AU2006/001775 4 end of a hollow threaded bar and this screw on drill tip results in the drill tip being significantly larger in diameter than the hollow bar itself. Typically, screw-on drill tips are at least 5mm larger in diameter than the hollow bar they are screwed onto. Self drilling rock bolts are available from many different manufacturers. Some 5 self drilling rock bolts use a tube for the hollow bar, where the wall thickness of the tube is relatively thin compared to the overall diameter of the tube. Typically the minimum ratio of the tube wall thickness to the tube diameter is about 1:8, and this limitation on the wall thickness is a result of the tube manufacturing process. For example, a tube with an external diameter of 38mm would have a maximum wall 10 thickness of about 4.5mm. To increase the wall thickness of a tube to increase the tensile strength, the diameter of the tube must also increase, and this means drilling a larger diameter borehole, and the use of more cement grout or resin which all adds to the cost of the installation. This is a disadvantage of using tubes for self drilling rock bolts because the wall thickness will always be relatively thin, which in turn will limit 15 the cross sectional area of steel that can be used for the bolt, which in turn will limit the tensile and shear strength of the self drilling rock bolt. In addition, tubes are manufactured with a plain external surface which is unsuitable for use as a rock bolt because a plain surface will have a very low bond strength with cement grout or resin which will anchor the bolt in the borehole. 20 Consequently, tubes have to have a thread profile or other rough surface profile formed on their external surface before they can be used as a self drilling rock bolt. This is an additional process that adds to manufacturing cost. Another disadvantage of using a tube in a self drilling rock bolt is the fact that because the central hole of the tube is relatively large compared to the overall 25 diameter of the tube, the volume of this central hole in the tube is large and requires considerable cement grout or resin to fill it. If cement grout is being used to fill this central hole, then this is relatively inexpensive and it does not add significantly to the overall installation cost. However, if expensive resin is being used to fill the central hole, then this can add to the cost of resin required and hence to the overall bolt 30 installation cost. Some self drilling rock bolt designs use a tube where the central hole of the tube is not used to pump cement grout or resin but contains a second smaller diameter WO 2007/059580 PCT/AU2006/001775 5 inner tube which in turn contains a resin cartridge. There is a gap between the inner diameter of the outer tube, and the outer diameter of the inner tube such that water can be pumped through this annulus space during the drilling cycle. Once the drilling cycle is complete, high pressure water is used to activate a piston or similar device to 5 force the resin out of the resin cartridge inside the inner tube. The resin which is pushed out of the end of the tube, flows back down around the outside of the self drilling rock bolt, but the central hole inside the self drilling rock bolt remains empty. The disadvantage of this is that corrosion can occur on the inside of the central hole, and the central hole of the tube can collapse-under extreme shear load thus reducing 10 the shear capacity of the bolt. Moreover, the plastic film surrounding the resin cartridge gets broken as the resin cartridge is pushed out of the end of the inner tube, and this plastic film can restrict the flow of resin coming out of the leading end of the tube. This broken plastic film can particularly restrict resin flow if a static mixer is used at the leading end of the tube to mix the mastic and catalyst components of the 15 resin. Finally having both an inner tube and an outer tube in this self drilling rock bolt design adds to the cost of production. Some other self drilling rock bolts use a plastic tube which surrounds a central solid steel bolt. The annulus space between the solid steel bolt and the surrounding plastic tube is used as the passageway for water flow for the drilling cycle, and then 20 can be subsequently used as a grout passageway during the grouting cycle. A drill bit is typically attached to the leading end of the solid steel bolt and an expansion shell friction anchor or similar device is typically mounted immediately behind it to provide a temporary anchoring mechanism. The problem with this type of self drilling rock bolt is that the plastic tube surrounding the solid bar provides very low load 25 transfer capacity because it is a relatively low friction interface between the grout and the solid bar. Another disadvantage with this design of self drilling rock bolt is that the expansion shell device provides very poor anchor capacity, and this bolt really needs to be post grouted with cement grout or resin to provide adequate rock support. However, post grouting requires a separate operation, and therefore this type of self 30 drilling rock bolt is not suited to automation of the bolting process. In addition, if cement grout is used to post grout these bolts, it would take many hours to cure and provide adequate rock support.

WO 2007/059580 PCT/AU2006/001775 6 The above disadvantages of tubes has resulted in the majority of existing self drilling rock bolts using thick-walled hollow bars rather than tubes. Self drilling rock bolts made from these thick-walled hollow bars are typically continuously threaded and are made by the expensive pierced billet method of hollow 5 bar production. Such self drilling rock bolts are typically between 20mm and 40mm in diameter and have a central hole of typically between 5mm and 20mm in diameter. Most of these self drilling rock bolts use a thick-walled hollow bar with a drill bit that screws onto the leading end of the hollow bar, often creating a large annulus space between the outside surface of the hollow bar and the borehole wall formed by the 10 drill bit, and this has the disadvantage that it requires a considerable volume of expensive resin to fill this annulus space. If cement grout is used instead of resin, then although cement grout is inexpensive, it has the disadvantage that it takes many hours to cure and anchor the self drilling rock bolt in the borehole. Some self drilling rock bolts use a thick-walled hollow bar with an expansion 15 shell anchoring device at the leading end of the rock bolt, just behind the drill tip. With this design of self drilling rock bolt, the drilling tip bores a relatively large diameter borehole in order to accommodate the diameter of the expansion shell. Once the borehole is drilled to its full depth, the self drilling rock bolt is then typically rotated in the opposite direction to expand the expansion shell device and anchor the 20 bolt in the borehole. The disadvantage of this design of self drilling rock bolt is that expansion shell devices provide very poor anchor capacity, and it is often necessary to come back and post grout the bolt and borehole with cement grout or resin. This is another separate operation that adds to the overall cost of the bolt installation. In summary, there are many different self drilling rock bolts currently 25 available from different manufacturers including: MAI, DSI, Ischebeck, Atlas Copco, Sandvik, Hilti, Schimdt & Kranz, SAH Ankertechnik, CarboTech-Minova, Alwag Tunnelausbau, Romtech, and Weidmann all from Europe, and Williams from the USA, Furen from China, and Steeldale SCS from South Africa. All of the self drilling rock bolts from the above manufacturers have most or all of the following features: 30 o they are designed to drill a borehole using water flushing of the rock cuttings; WO 2007/059580 PCT/AU2006/001775 7 o they use a drill tip which screws onto the end of the self drilling bolt and which creates a large annulus space between the inside surface of the borehole wall and the outside surface of the hollow bar of typically greater than 4mm; 5 o they use a hollow bar which has a cold rolled thread along its entire length; o they anchor the bolt by using either: - cement grout by screwing a grouting hose onto the end of the bolt and then pumping the grout through the 10 central hole and back down around the outside of the bolt; or by using - a resin cartridge which is pushed out of the end of the bolt such that the resin cartridge ruptures and the resin is forced to flow through the end of the bolt commonly 15 through a static mixer and back down around the outside of the bolt; or by using - an expansion shell on the leading end of the bolt which is expanded inside the borehole once the borehole is drilled to its full depth. 20 The above existing self drilling rock bolts have one or more of the following disadvantages: " they are not suited to automatic installation but still require considerable manual handling to install; * they are designed to be anchored with cement grout which takes many 25 hours to cure and does not provide immediate roof support; e they are designed to be used with resin cartridges can have problems with poor resin mixing and incomplete bolt encapsulation; e they typically have a large annulus space surrounding the bolt; " they typically use expensive screw on type drilling tips; WO 2007/059580 PCT/AU2006/001775 8 * they typically do not have their own internal seals to mate and hydraulically seal with the drilling machine against leakage of pumped fluids through the bolt; 0 they typically do not have their own internal valves to control or direct 5 the flow of fluids pumped through the bolt; * they typically do not have their own internal static mixers located at -the exposed end or nut end of the bolt so that any resin or grout that remains in the central hole of the bolt will not be thoroughly mixed by the static mixer and has the potential to drip back out of the central 10 hole of the bolt; * they either cannot be tensioned up, or do not have a simple rotational drive and tensioning system but require the use of separate drive sockets to rotate the bolt during the drilling cycle, then tension the nut during the tensioning cycle of the installation. 15 The current invention overcomes the above problems with existing self drilling rock bolts and provides a self drilling rock bolt suited to be automatically or semi-automatically installed with a machine. With existing self drilling rock bolts, there is firstly, the requirement to pump water through the central hole of the bolt during the drilling cycle to flush the rock 20 cuttings out of the borehole, and this is usually achieved by having a water seal in the drill chuck of the drilling machine. Secondly, there is the requirement to anchor the self drilling rock bolt in the borehole. If this anchoring of the bolt in the borehole is achieved by pumping cement grout or resin through the self drilling rock bolt, then there is the requirement to provide a seal between the hose from the grout pump and 25 end of the rock bolt. With existing self drilling rock bolts using cement grout, this seal is achieved by tightly screwing a grout hose fitting onto the end of the self drilling rock bolt. However, if resin is to be pumped through the self drilling rock bolt to anchor the bolt in.the borehole, then a better sealing arrangement is required than is currently 30 available with existing self drilling rock bolts. Firstly, polyester resin comes in two parts, namely a mastic component and a catalyst component, and they must be kept completely separated from each other until they need to be cured and hardened. This WO 2007/059580 PCT/AU2006/001775 9 means that-they cannot be brought -together outside of the self drilling rock bolt otherwise they will react with each other and cure and harden. Consequently, the mastic and catalyst components of the resin must be kept in separate tanks, and in separate hosing as well as using separate pumps for both the mastic and catalyst 5 components of the resin. The separate hose lines for the mastic component and the catalyst component of the resin are fed through to the drill chuck on the drilling machine. An additional separate hose line for the water used in the drilling operation, is also fed through to the drill chuck on the drilling machine, and is also kept separate from the mastic and catalyst hose lines. 10 The present invention also'provides a self drilling rock bolt whereby the separate passageways for the mastic, the catalyst and the water can be accommodated in the end of the self drilling rock bolt. The present invention also provides a mechanism whereby the separate passageways for the mastic, the catalyst and the water can be sealed by a seal or seals 15 in the end of the of the self drilling rock bolt which provides an adequate hydraulic seal for mastic, catalyst and water which is pumped into the self drilling rock bolt. The present invention provides a new seal or seals in the end of every self drilling rock bolt to ensure that the seals do not leak when fluids are being pumped into the self drilling rock bolt. 20 The present invention provides a valve or valves in the end of every self drilling rock bolt to ensure that the flow of fluids is controlled when they are being pumped into the self drilling rock bolt. The present invention provides a static mixer in every self drilling rock bolt to ensure that if a two part resin is pumped through the self drilling rock bolt it is 25 thoroughly mixed and will cure and harden. The present invention also provides a female injection sleeve on the end of the self drilling rock bolt which can accommodate a male injection nozzle. The present invention also provides a female injection sleeve on the end of the self drilling rock bolt whereby the sleeve also functions as a nut stop device such that 30 the nut cannot be unscrewed from the self drilling rock bolt so that rotation of the nut against the sleeve can be used to rotate the bolt during the drilling cycle of the installation.

WO 2007/059580 PCT/AU2006/001775 10 The present invention also provides a mechanism whereby the nut on the self drilling rock bolt can be tensioned up by rotating the nut away from the injection sleeve and without having the requirement to use a separate drive socket or drive dolly. 5 The present invention also provides a self drilling rock bolt suited to installation with a minimum of manual handling required, and is suited to automation or semi-automation of the installation process using pumpable bulk resin. Resin cartridges to anchor a rock bolt are no longer required with the current invention. Objects of the Invention 10 It is an object of this present invention to provide a self drilling rock bolt which enables pumpable resin to be used to anchor the rock bolt in a borehole which overcomes all of the disadvantages with existing self drilling rock bolts listed above, as well as providing some additional benefits for the installation and performance of. self drilling rock bolts. 15 The present invention provides a self drilling rock bolt with an internal seal to provide a hydraulic seal against fluids pumped from a drilling machine into the self drilling rock bolt. The present invention provides a self drilling rock bolt with an internal valve system to ensure the correct flow of fluids inside a self drilling rock bolt. 20 The present invention provides a self drilling rock bolt with an internal static mixer at the nut end of the bolt to ensure that the resin in the central hole of the bolt is thoroughly mixed together. . The present invention provides a self drilling rock bolt with one or more internal strain gauges or measurement devices that are electrically connected to a 25 device on the exposed end of the self drilling rock bolt that enables readings to be easily taken of those strain gauges. The present invention provides a self drilling rock bolt comprising a thick walled, hot rolled hollow bar with an external profile, with an integral drilling tip, nut, domed ball, drive system, static mixer, hydraulic sealing and valve system, and strain 30 gauge and strain gauge reading device that provides considerable performance and installation benefits compared to existing self drilling rock bolts.

WO 2007/059580 PCT/AU2006/001775 11 The present invention provides a self drilling rock bolt that is suited to automatic or semi-automatic installation using drilling machines with custom made drilling chucks. Summary of the Invention 5 According to the present invention there may be provided a self drilling rock bolt comprising a hollow elongate bar with a threaded section on at least one end of the bar which is threadably engaged with a drive and tensioning nut with a domed ball positioned in front of the nut on the bar, and with a hollow injection sleeve fixed to the end of the bar behind the nut such that the sleeve prevents the nut from being 10 removed from the bar, and with the central hole of the hollow bar substantially containing a static mixer close to the nut end of the bar, and with the opposite end of the hollow elongate bar having a drilling tip rotatably fixed to the bar. The central hole of the hollow elongate bar may also contain one or more strain gauges or other load or measurement device within it and which is connected to a reading device or 15 electrical contacts on the exposed end of the rock bolt. Typically the hollow elongate bar consists of a hot rolled, hollow steel bar which has either a threaded section at one end of the bar or is continuously threaded all along the whole length of the bar. The threaded section of the bar is typically at least 1 00mm long. The bar may be partly or continuously threaded and may have hot 20 rolled threads, cold rolled threads or machined threads, and may have any suitable thread form. Typically the drive and tensioning nut consists of a hexagonal or square steel nut threadably engaged with the threaded section on the bar. Alternatively, the drive nut may be fixed to the end of the hollow elongate bar and may not be advanced 25 along a screw thread and be tensioned up against the domed ball or rock face. As a further alternative, if the drive nut is fixed to the elongate member, the drive nut may also incorporate the injection sleeve. Typically the domed ball consists of a heavy steel washer which fits on the bar with a hemispherical face on one side facing towards the rock face and a flat 30 face facing towards the nut. Alternatively the end of the nut facing towards the rock face may have a hemispherical face formed on it.

WO 2007/059580 PCT/AU2006/001775 12 Typically the hollow injection sleeve consists of a hollow steel tube where the central hole of the injection sleeve is larger in diameter than the hole in the middle of the hollow bar. Typically a section of the injection sleeve is screwed onto the end of the elongate hollow bar and or is tack welded or glued to the bar to prevent the 5 injection sleeve from being unscrewed off the bar. The injection sleeve contains one or more seals to hydraulically seal against leakage of fluids being pumped into the self drilling rock bolt. The injection sleeve also acts as a nut stop and rotational drive mechanism for the self drilling rock bolt by preventing the nut from being unscrewed off the hollow elongate bar whereby rotation of the nut against the injection sleeve 10 causes the hollow elongate bar to rotate and this is used to rotate the self drilling rock bolt during the drilling cycle of the bolt installation. Typically the static mixer consists of a series of plastic offset spirals, but can be any shape that will mix a fluid or fluid components together. Typically the drilling tip consists of a hardened flat steel drill tip as per 15 Australian patent number 5428 1/01. Typically the strain gauges or other load or measurement device consists of one or more strain gauges or other measurement devices located within the central hole of the hollow elongate bar and may be secured in position with respect to the bar by the resin or cement grout or may be secured in position by some other means, and 20 are connected to the exposed end of the self drilling rock bolt such that readings can easily be taken from a reader device on the exposed end of the bolt. The self drilling rock bolt may be any suitable length, and different length self drilling rock bolts are typically made by varying the length of the hollow elongate bar, 25 In operation the nut end of the self drilling rock bolt is placed in a drive or drilling chuck on a drilling machine and the hexagonal nut fits into a female hexagonal drive socket and the female injection sleeve fits over a male injection nozzle in the drilling chuck. The male injection nozzle forms a tight hydraulically sealing fit with the seal or seals inside the female injection sleeve on the end of the 30 self drilling rock bolt. The drilling machine then raises the self drilling rock bolt until it touches the exposed rock face, and then water is pumped from the drilling machine through WO 2007/059580 PCT/AU2006/001775 13 the drilling chuck and through the injection nozzle into the bolt. The seals in the injection sleeve prevent water leakage from the bolt. If a valve or valves are also used in the end of the self drilling rock bolt or in the end of the injection nozzle, then the water pressure will typically open this valve and water is pumped through the central 5 hole of the bolt and out of the drilling tip end of the bolt where this water assists with flushing and removal of rock cuttings from the drilling operation. The drilling machine then causes the female hexagonal drive socket to rotate which in turn rotates the nut back against the injection sleeve on the end of the hollow elongate bar until the nut cannot be unscrewed along the bar any further 10 because the injection sleeve acts as a nut stop. Further rotation of the nut causes the whole self drilling rock bolt assembly to rotate. The drilling machine then also applies axial thrust and the drilling tip on the leading end of the self drilling rock bolt is then pressed against the exposed rock face and then the drilling tip can then drill the required borehole in the rock face. Once the borehole is drilled to its full depth, 15 rotation and water flow are turned off. If a two part polyester resin is then used to anchor the self drilling rock bolt in the borehole, then the resin flow is turned on. The mastic and catalyst components of the resin are pumped through their separate flow lines and passageways and are pumped up through the injection nozzle. The mastic and catalyst 20 components of the resin are finally brought together inside the injection sleeve on the end of the self drilling rock bolt. A flow control valve or valves or other device prevents the mastic and catalyst resin components from flowing down the wrong passageways in the injection nozzle, such that the mastic and catalyst is forced to flow through the static mixer in the central hole inside the self drilling rock bolt. The static 25 mixer causes the mastic and catalyst components of the resin to be thoroughly mixed together such that the mixed resin starts to cure once it has passed through the static mixer. Further pumping of the resin causes the mixed resin to flow out of the end of the self drilling rock bolt and flow back down around the bolt and fill the annulus space surrounding the bolt between the bolt and the borehole wall. The cure time for 30 the resin is designed to just allow the resin to flow back down to the nut end of the bolt and to fully encapsulate the self drilling rock bolt with resin. Once the self drilling rock bolt is fully encapsulated with resin, the resin pump is turned off and the resin is allowed to cure for the designed set time (typically WO 2007/059580 PCT/AU2006/001775 14 between 10 seconds and 60 seconds), such that the resin is securely anchoring the self drilling rock bolt inside the borehole. The rotation of the drilling chuck is then reversed such that the nut then rotates away from injection sleeve and tightens up against the domed ball and bearing plate against the rock face. The final step of the 5 installation of the self drilling rock bolt is that the drilling chuck is then lowered away from the installed self drilling rock bolt back to its starting position. The present invention enables a self drilling rock bolt to be installed in a semi automatic or an automatic manner with a two part resin compound being pumped and mixed through the central hole in the bolt to anchor the bolt in the 10 borehole. In operation the present invention enables a self drilling rock bolt to have a simple and reliable rotational mechanism to allow the bolt to be rotated to drill a borehole. In operation the present invention enables any hollow bolt or hollow bar 15 to have a simple and reliable load, movement and strain measuring system to be incorporated into the central hole of the bolt and with a simple device to take readings located at the exposed end of the hollow self drilling rock bolt. In operation the present invention obviates the need for resin cartridges, separate drill rods with separate drill bits, and drive dollies which are currently needed 20 to install conventional tensionable rock bolts. In an embodiment of the invention, the rock bolt can be made from steel, stainless steel, fibreglass, carbon fibre, plastic or any other suitable material. In a preferred embodiment of the invention, the rock bolt is made from steel. 25 In a preferred embodiment of the invention, the self drilling rock bolt is made from a partially or continuously threaded, thick-walled, hollow steel bar with a steel drilling tip, a steel nut, a steel domed ball, a steel injection sleeve with seals, and with a plastic static mixer. In a further preferred embodiment of the invention, the self drilling rock 30 bolt has a valves or valves to control and direct the flow of fluids in the bolt.

WO 2007/059580 PCT/AU2006/001775 15 In one embodiment of the invention the self drilling rock bolt has strain gauges or other measurement devices contained substantially within the central hole of the bolt which are electrically connected to an electrical reading device or devices or electrical contacts located on the outside of the injection sleeve. The electrical 5 reading devices or electrical contacts are typically circular and go around the outside circumference of the injection sleeve. In another embodiment of the invention, the drilling tip located on the leading end of the self drilling rock bolt drills a borehole that has a diameter that is just sufficient to clear the rock cuttings during the drilling operation. In operation this 10 would typically provide an annulus between the bolt and the borehole wall of 3mm, and this would minimise the volume of resin required to fill the annulus and fully encapsulate the bolt, and would also maximise the load transfer capacity of the bolt. In another embodiment of the invention, the drilling tip located on the leading end of the self drilling rock bolt is designed to drill a borehole that has a 15 diameter that generates a large annulus between the bolt and the borehole wall of approximately 5mm or more. In this embodiment, once the annulus space were completely filled with resin or cement grout, the filled annulus would provide a significant barrier to water and potential corrosion affecting the bolt. Description of the Drawings 20 In order that the invention may be more readily understood and put into practical effect, reference will now be made to the accompanying drawings. For consistency, item numbers refer to the same feature or design aspect in all figures. Figure 1 is a sectional view of a self drilling rock bolt 1 comprising a substantially round hollow elongate bar 2 with a central hole 3 and with a ribbed 25 external profile 4. The ribbed external profile 4 may be formed in a hot rolling process or be formed in a cold rolling process or may be machined onto the bar. The ribbed external profile 4 may or may not form a thread form. One end of the hollow elongate bar 2 may have a section with a threaded external profile 5 with a relatively fine thread pitch of between 2 and 6mm but is not limited to these thread pitches. In' 30 practice the self drilling rock bolt 1 is a long elongate member typically one to three meters long, and in order to show both ends of the bolt in Figure 1, a diagrammatic break is shown as 26 in Figure 1.

WO 2007/059580 PCT/AU2006/001775 16 Figure 1 also shows a drilling tip 6 located in the leading end of the hollow elongate bar 2 where the maximum diameter of the drilling tip 7 is greater than the maximum diameter of the hollow elongate bar 2 over the ribs 4. The drilling tip 6 has a locating tang 8 which is located in a short hole 9 at the leading end of the hollow 5 elongate bar 2 whereby hole 9 may be larger in diameter than the central hole 3. Figure 1 also shows that the drilling tip 6 may be fixed to the bar 2 by welding 28. Drilling tip 6 is typically made from flat steel as described in Australian patent number 54281/01. Figure 1 also shows a domed ball 10 slidably assembled onto the hollow 10 elongate bar 2 and a nut 11 rotatably assembled onto the threaded section 5 of the hollow elongate bar 2. Figure 1 also shows an injection sleeve 12 with at least one internal seal 13 and with an internal hole 14 which typically has a larger diameter than hole 3 in the elongate bar 2 of the self drilling rock bolt 1. Figure 1 also shows that the injection 15 sleeve 12 may be rotatably assembled onto threaded section 5 the hollow elongate bar 2 and is permanently fixed to the bar 2 by welding or gluing or similar means (not shown). Figure 2 is a plan view of the self drilling rock bolt 1 and shows hot rolled ribs 4 extending partially around the circumference of the hollow elongate bar 2 and 20 on opposite sides of the bar 2. Figure 2 also shows that the ribs 4 on opposite sides of the bar 2 are helically aligned along a thread helix such that they form a thread form. Figure 3 shows a plan view of the self drilling rock bolt 1 which shows an alternative hollow elongate bar 2 with a section comprising a threaded external profile 5 with a relatively fine thread pitch, and with a remaining section comprising another 25 threaded external profile 25 with a coarser thread pitch than 5 and which extends around the full circumference of the bar 2. The thread profiles 5 and 25 may be either left hand threads or right hand threads. Figure 4 shows a side elevation view of the self drilling rock bolt 1 which shows a further alternative hollow elongate bar 2 with a continuous threaded external 30 profile 25 which extends around the full circumference of the bar 2 and which also forms a thread form 25. Figure 4 also shows the side elevation view of the drilling tip 6 and shows that the drilling tip 6 is typically made from flat steel as shown and as WO 2007/059580 PCT/AU2006/001775 17 described in Australian patent number 54281/01. Figure 4 also shows an alternative method of fixing the drilling tip 6 to the bar 2 whereby the drilling tip 6 is rotatably fixed to the bar 2 by being located in a keyway 27 in the bar 2. Figure 5 is a sectional view of a self drilling rock bolt 1 comprising a 5 substantially round hollow elongate bar 2 with a central hole 3 and with a threaded external profile 25. Figure 5 also shows a drilling tip 6 located in the leading end of the hollow elongate bar 2 where the maximum diameter of the drilling tip 7 is greater than the maximum diameter of the hollow elongate bar 2. Figure 5 also shows an 10 alternative arrangement for securing the drilling tip 6 to the bar 2 whereby the flat drilling tip 6 has tapered sides 29 that fit into a short tapered hole 30 at the leading end of the hollow elongate bar 2 as described in Australian patent number 54281/01. Figure 5 also shows a sectional view of a static mixer 17 located in a neatly fitting hole 16 at the nut end of the self drilling rock bolt 1. The hole 16 15 extends for at least the length of the static mixer 17 and is typically slightly larger in diameter than hole 3 in the bar 2 but could be any suitable diameter and could be formed from a hollow plastic tube or similar (not shown) inserted into the hole 3 in the bar 2. Figure 5 also shows a sectional view of a domed ball 10 which can slide 20 along the bar 2 and a nut 11 which is rotatably assembled onto the thread 25 on the bar 2. Figure 5 also shows a sectional view of an injection sleeve 12 with at least one internal seal 13 and with an internal hole 14 which typically has a larger diameter than hole 3 in the elongate bar 2 of the self drilling rock bolt 1. Figure 5 also shows 25 an alternative assembly of the injection sleeve 12 onto the bar 2 whereby the injection sleeve 12 fits onto a machined stub 32 on the bar 2 and the injection sleeve12 is fixed to the stub 32 by welds 31. Figure 5 also shows a sectional view of an injection sleeve 12 with an optional internal valve 15. 30 Figure 6 shows an end view of the self drilling rock bolt 1 from the injection sleeve 12 end showing the hollow bar 2, the round domed ball 10, the WO 2007/059580 PCT/AU2006/001775 18 hexagonal nut 11, the round injection sleeve 12, the internal seal 13 and with an optional internal valve 15. Figure 7 shows an end view of the self drilling rock bolt 1 from the drilling tip 6 end showing the hole 3 in the hollow bar 2, the hemispherical face of the 5 round domed ball 10, and the flat drilling tip 6. Figure 8 shows a three dimensional view of the self drilling rock bolt 1 from the injection sleeve 12 end and shows the large diameter hole 14 in the injection sleeve 12 to facilitate resin or cement grout injection and the internal seals 13 in the injection sleeve 12 which also contains the internal valve 15. Figure 8 also shows a 10 nut 11 that can advance along a thread 5 and a domed ball 10. Figure 8 further shows a hollow elongate bar 2 with a threaded external profile 25 which extends around the full circumference of the bar 2 and which also forms a thread form 25 and a drilling tip 6 whereby the drilling tip 6 may be rotatably fixed to the bar 2 by being located in a keyway 27 in the bar 2. 15 Figure 9 shows a three dimensional view of the self drilling rock bolt 1 from the drilling tip 6 end and shows that the flat drilling tip 6 design forms two passageways in the hole 9 on either side of the drilling tip 6 to allow water and resin to come out of the hollow elongate bar 2. Figure 9 also shows that the drilling tip 6 may be rotatably fixed to the bar 2 by being located in a keyway 27 in the bar 2. 20 Figure 9 also shows a bar 2 with a threaded external profile 25 and a section of relatively fine pitch thread 5 with a nut 11 and domed ball 10. Figure 9 also shows the injection sleeve 12 at the nut end of the bar 2. Figure 10 is a sectional view of one embodiment of a self drilling rock bolt 1 showing an internal static mixer 17 located in a short section of central hole 16 25 in the hollow elongate bar 2 whereby the hole 16 may be larger in diameter than the remaining section of central hole 3 in the hollow elongate bar 2. Figure 10 also shows a flow valve 15 and internal seals 13 contained within the sleeve 12 of the self drilling rock bolt 1. Figure 10 also shows an alternative assembly of the injection sleeve 12 onto the bar 2 whereby the injection sleeve 12 fits onto a machined stub 32 on the bar 30 2 and the injection sleevel2 is fixed to the stub 32 by welds 31. Figure 10 also shows ' that the internal hole 14 in the sleeve 12 is typically larger in diameter than the hole 3 in the bar 2. Figure 10 also shows the bar 2 with a continuous threaded external WO 2007/059580 PCT/AU2006/001775 19 profile 25 whereby the nut 11 can rotate and advance along the thread 25. Figure 10 also shows the drilling tip 6 may be rotatably fixed to the bar 2 by being located in a keyway 27 in the bar 2. Figure 11 is a sectional view of another preferred embodiment of a self 5 drilling rock bolt 1 showing internal strain gauges or measurement devices 20 located inside the central hole 3 and spaced along the hollow elongate bar 2. The strain gauges 20 are electrically connected by wires 19 to a reading device or devices 18 located on the outside of the injection sleeve 12. Figure 11 also shows the drilling tip 6 fixed to the bar 2 by welds 28. 10 Figure 12 is an end view of an injection nozzle 24 that would be contained within a drilling chuck (not shown) of a drilling machine (also not shown). The injection nozzle 24 has one or more separate passageways 21, 22 and 23 for different fluids that can be pumped into the self drilling rock bolt. Figure 13 is a sectional view of the nut 11 end of the self drilling rock bolt 15 1 showing how the injection nozzle 24 from the drilling machine (not shown) fits into the injection sleeve 12 and that the injection nozzle 24 seals against seals 13 inside the sleeve 12 and that the valve 15 can control the flow of fluids pumped from the injection nozzle 24 into the self drilling bolt 1. Figure 14 is a side elevation view of the nut 11 end of the self drilling 20 rock bolt 1 showing how the injection nozzle 24 from the drilling machine (not shown) fits into the injection sleeve 12. Figure 12 also shows the electrical reading device or devices 18 located on the outside of the injection sleeve 12. The reading device or devices 18 are typically circular and go around the outside circumference of the injection sleeve 12 and readings are taken by using a mating female electrical 25 device (not shown) that fits over the injection sleeve 12 and electrically contacts the reading device or devices 18. Detailed Description of the Preferred Embodiments One embodiment of the present invention is shown in Figure 1. Figure 1 shows a self drilling rock bolt 1 that is particularly suited for use with cement grout or 30 with a single part chemical compound. Figure 1 shows a hollow bar 2 with hot rolled ribs 4 and with a section with a threaded external profile 5 with a relatively fine thread pitch to accommodate a nut 11. In operation, the drilling operation can be WO 2007/059580 PCT/AU2006/001775 20 accomplished by placing the nut 11 into a socket (not shown) in the drilling chuck on the drilling machine (also not shown). The socket can then rotate the nut 11 back against the injection sleeve 12 such that the whole self drilling rock bolt 1 can also be rotated. An injection nozzle inside the drilling machine (not shown) can fit inside the 5 injection sleeve 12 and can enable water to be pumped into the bolt during the drilling cycle, and cement grout to be pumped through the bolt during the grouting cycle. Figure 1 does not show a static mixer because it is not required if cement grout is used to anchor the bolt in the borehole. Cement grout can then be pumped through the central hole 3 and out of the end of the bolt past the drill bit 6 and can then be pumped 10 back down the annulus space around the outside of the bar 2. The nut 11 can be subsequently be tensioned up when the cement grout has cured. Another embodiment of the present invention is shown in Figure 2 which shows an alternative hollow elongate bar 2 where the external ribs 4 are along the whole length of the bar 2 and form a thread form which a nut 11 is threadably 15 engaged with. Another embodiment of the present invention is shown in Figure 3 which shows a further alternative hollow elongate bar 2 with a threaded section with a relatively fine thread pitch 5 which a nut 11 is threadably engaged with, and with a remaining section comprising another threaded external profile 25 with a coarser 20 thread pitch than 5 and which extends around the full circumference of the bar 2. Another embodiment of the present invention is shown in Figure 4 which shows a further alternative hollow elongate bar 2 with a continuous threaded external profile 25 which extends around the full circumference of the bar 2 and which a nut 11 is threadably engaged with. 25 Another embodiment of the present invention is shown in Figure 5 which shows a hollow elongate bar 2 with a central hole 3 and with a threaded external profile 25 and with an internal static mixer 17 and an internal valve 15 and with internal seals 13 and with a drilling tip 6 with tapered sides 29. Another embodiment of the present invention is shown in Figure 11 which 30 shows a hollow elongate bar 2 with internal strain gauges or measurement devices 20 located inside the central hole 3.

WO 2007/059580 PCT/AU2006/001775 21 In one preferred embodiment of the present invention, the nut 11 and the injection sleeve 12 of the self drilling rock bolt 1 are placed in a drill chuck of a drilling machine (not shown) and then water is pumped into the bolt 1 from the drilling chuck (not shown). In a preferred embodiment, water would be pumped 5 through a water passageway 21 in an injection nozzle 24 as shown in Figures 12 and 13 which would be inserted inside the injection sleeve 12 and would seal against a seal 13 inside the injection sleeve 12. Alternatively, the drill chuck (not shown) could contain a seal (also not shown) which would seal against the outer. surface of the injection sleeve 12. 10 In a further preferred embodiment, the water passageway 21 would fit into a valve 15 inside the injection sleeve 12. In operation, water would pass through the water passageway 21 and the water pressure would open the valve 15 such that water could flow through the central hole 3 in the bolt 1 and out of the end of the bolt 1 at the drilling tip 6. The drill chuck would then rotate the nut 11 such that the nut 11 15 would unscrew back against the sleeve 12 until the nut 11 could not rotate any further with respect to the bar 2, and then further rotation of the nut 11 would cause the whole self drilling rock bolt 1 to rotate and drill a borehole (not shown) in rock. When the borehole (not shown) is drilled to its correct depth, rotation of the bolt 1 is stopped and the water flow is turned off causing the valve 15 in the injection sleeve 12 to 20 close. Once the drilling operation is complete, the resin pump (not shown) is turned on and the mastic component of the resin is pumped through the mastic passageway 23 in the injection nozzle 24, and the catalyst component of the resin is pumped through the catalyst passageway 22 in the injection nozzle 24. Once the 25 mastic leaves the end of the mastic passageway 23, and the catalyst leaves the end of the catalyst passageway 22, the mastic and the catalyst are in contact with each other for the first time inside the injection sleeve 12. The one-way valve 15 inside the injection sleeve 12 prevents the mastic and catalyst being pumped down the water passageway 21 inside the injection nozzle 24. The mastic and catalyst are then 30 pumped through the injection sleeve 12 and then through a static mixer 17 contained within a central hole 16 at the injection sleeve 12 end of the bolt 1. As the mastic component of the resin and the catalyst component of the resin are pumped through WO 2007/059580 PCT/AU2006/001775 22 the static mixer 17, they are mixed together such that they are thoroughly mixed together once they leave the static mixer 17. Further pumping causes the mixed resin to move through the central hole 3 in the bolt 1 until it reaches the drill bit 6 and flows out of the hole 9 at the drill tip 6 5 end of the bolt 1. The central hole 9 at the drill tip 6 end of the bolt 1 may be larger in diameter than hole 3 in the bolt 1 to accommodate a location tang 8 on the end of the drill bit 6. Holes 14, 16, 3 and 9 are interconnected such that resin and water will flow progressively through them. The drill tip 6 is designed to have a larger diameter 7 than the bar 2 such that the drill tip 6 will form a borehole (not shown) that will 10 enable the bar 2 to fit within it and form an annulus (also not shown) between the outer surface of the bar 2 and the inside surface of the borehole wall (not shown). Further pumping of the resin causes the mixed resin to flow out of the drill tip 6 end of the bar 2 and back down along the annulus space (not shown) until the bar 2 is fully encapsulated in the borehole (also not shown) with mixed resin. Once this occurs, 15 resin pumping is turned off and the mixed resin is allowed to cure and harden. Typically the resin is designed to cure and harden within 15 seconds but it could be any time between a few seconds and several hours. Once the resin is cured and has hardened, the drill socket (not shown) in the drilling chuck on the drilling machine (also not shown) is rotated such that the nut 20 11 screws away from the injection sleeve 12 on the bar 2, and is tightened up against the domed ball 10 which in turn is pressing against a bearing plate (not shown) supporting the rock face (also not shown) or supporting mesh (also not shown) which in turn is supporting the rock face. The domed ball 10 may be incorporated as part of the nut 11 by using a hemispherical face (not shown) on the leading face of the nut 11, 25 or the domed ball 10 may be a separate component as shown, or may be omitted altogether. Once the nut 11 is tightened up, rotation of the drill socket (not shown) in the drilling chuck (also not shown) is stopped, and the drilling chuck on the drilling machine (also not shown) is retracted away from the rock face to complete the 30 installation of the bolt 1. The invention will be described with respect to self drilling rock bolts, but the invention is not limited to this application only and could be applied to any hollow WO 2007/059580 PCT/AU2006/001775 23 bolt or bar where fluids need to be injected through a hollow bar. The invention is particularly applicable to hollow self drilling rock bolts but again is not so limited. Many rock bolts use a nut on a threaded section on one end of the rock bolt in order to tighten up the nut against a bearing plate and apply tension to the bolt. 5 This tension in the bolt applies a support force to the rock mass, and is a desirable attribute of rock bolts. Nuts are also used to rotate rock bolts to mix resin which is contained in a frangible cartridge up a pre-drilled borehole. The present invention provides an injection sleeve 12 on a hollow bar 2 that not only enables fluids to be pumped into a hollow bar 2, but also enables a nut 10 11 to rotate the hollow bar 2 by providing a fixed stop at the end of the hollow bar 2 that prevents the nut 11 from being rotationally unscrewed from this end of the hollow bar 2. The present invention also provides an injection sleeve 12 on a hollow bar 2 with internal seals 13 that can provide a hydraulic seal with an injection nozzle 24. 15 The present invention also provides an injection sleeve 12 on a hollow bar 2 that can accommodate an injection nozzle 24 with multiple fluid passageways. The present invention also provides an injection sleeve 12 on a hollow bar 2 that may have an internal valve or valves 15 that can control the flow of fluids being pumped into the injection sleeve 12. 20 The present invention also provides an injection sleeve 12 on a hollow bar 2 that may have external monitoring devices 18 on its outer surface 12 which are connected 19 to internal instrumentation 20 inside the central hole 3 in the hollow bar 2. The present invention also provides for a static mixer 17 inside a hole 16 25 inside the hollow bar 2. The present invention also provides for a drill bit 6 with a locating tang 8 inside a hole 9 at the leading end of the hollow bar 2. The present invention also comprises an assemblage of components as previously described which form a self drilling rock bolt. 30 The present invention does not require the use of a separate resin cartridge, or separate drill rod and drilling tip, or separate drive dolly and hence WO 2007/059580 PCT/AU2006/001775 24 removes considefable manual labour as well as reducing injuries to operators. The present invention makes it possible to install rock bolts using automatic or semi automatic drilling machines. The present invention has the advantage that the self drilling rock bolt 5 described in this invention has the advantage that once it is placed in the drilling chuck of the drilling machine, the drilling machine can then fully install the bolt without any requirements to separately post grout the bolt or undertake any additional operations. It should be noted that the invention can be applied to both right hand 10 threaded and left hand threaded bars and rock bolts. 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 also includes all of the steps, features, compositions, and compounds 15 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 20 understood to imply 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 "self drilling rock bolt" it is to be understood that the invention includes all such variations and modifications of the above. 25 Where the specification refers to a "bar" or to a "hollow bar" or to an "elongate bar" or to a "hollow elongate bar" or to an "elongate member" or to a "hollow elongate member" or to an "elongate hollow threaded bar" or to a "hollow threaded bar" or to a "hot rolled threaded bar" or to a "hollow threaded member" or to a "hollow threaded section" it is to be understood that the invention includes all such 30 variations and modifications of the above and any other hollow elongate bar or bolt or tube that has a substantially centralised continuous hole within it along its axial length.

WO 2007/059580 PCT/AU2006/001775 25 Where the specification refers to a "profile" it is to be understood that the invention includes all such variations and modifications of the above, including hot rolled ribs, hot rolled ribs that are aligned to form a thread form, machined threads, machined ribs, and cold rolled threads of any thread form, and any other bar profile 5 that can improve the load transfer capacity of the bar. Where the specification refers to a "seal" or to "seals" or to a "female seal" it is to be understood that the invention includes all such variations and modifications of the above, including 0 rings, glide seals, bush seals, pressure seals, or any other device that will form a hydraulic seal for fluids. 10 Where the specification refers to a "valve" or to "valves" or to an "internal valve" or to a "water valve" or to a "one way water valve" it is to be understood that the invention includes all such variations and modifications of the above, including needle valves, ball valves, cone valves, separate passageways, or any other device that will control and or direct the flow of fluids. 15 Where the specification refers to a "nut" or to a "drive nut" it is to be understood that the invention includes hexagonal, square and any other non-circular shaped nuts and all such variations and modifications of the above and any other member that could fit into a drive socket and be used to rotate a self drilling rock bolt. Where the specification refers to a "domed ball" it is to be understood that 20 the invention includes all such variations and modifications of the above and any other member that could be used to provide angular adjustment against a bearing plate or rock face and is typically a separate thick washer with one hemispherical face, but the domed ball could be incorporated as an integral part of a nut. Where the specification refers to a "drill tip" or to a "drilling tip" or to a 25 "drilling bit" or to a "drill bit" 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 drill a hole in rock or clay or soil. Where the specification refers to a "static mixer" or to "static mixer elements" or to a "mixer" it is to be understood that the invention includes all such 30 variations and modifications of the above, including mixer spirals, offset mixer spirals, offset mixer segments, offset mixer elements, either with or without a WO 2007/059580 PCT/AU2006/001775 26 surrounding plastic tube, and any other device that could be used to mix two or more fluids together. Where the specification refers to a "hollow injection sleeve" or to an "injection sleeve" or "sleeve" or "female injection sleeve" it is to be understood that 5 the invention includes all such variations and modifications of the above, including a sleeve with a substantially centralised hole and any other member that could be used to accommodate a male injection nozzle. Where the specification refers to an "injection nozzle" or "nozzle" it is to be understood that the invention includes all such variations and modifications of the 10 above, and any other member that could be seal against a self drilling rock bolt and that the nozzle may have one or more passageways for the flow of fluids. Where the specification refers to "passageways" it is to be understood that the invention includes all such variations and modifications of the above, including tubes, pipes, holes, and any other member that could be used to transport fluids. 15 Where the specification refers to an "external monitoring device" or to "electrical reading device or devices" or to "electrical contacts" it is to be understood that the invention includes all such variations and modifications of the above, including any device that can provide an electrical connection with remote instrumentation. 20 Where the specification refers to "internal instrumentation' or to "gauges" or to "strain gauges" or to "measurement devices" it is to be understood that the invention includes all such variations and modifications of the above, including any device that can monitor movement, or stress or strain.

Claims

1. A self drilling rock bolt comprising an assemblage of a hollow elongate member with a drilling tip on the leading end of the elongate member, a hollow injection sleeve fixed on the other end of the elongate member to the drilling tip, the 5 hollow injection sleeve being adapted to accommodate an injection nozzle, and a nut on the elongate member adapted to rotate the self drilling rock bolt, further including a valve member located within the hollow injection sleeve and adapted to close off a fluid passage of the injection nozzle.

2, A self drilling rock bolt according to Claim 1, wherein the valve member is 10 adapted to open under pressure of fluid in the fluid passage to allow flow of fluid from the fluid passage, and to close to prevent a reverse flow of fluid entering the fluid passage..

3. A self drilling rock bolt according to Claim I or 2, wherein the hollow elongate member has at least one threaded section on the outside surface of the 15 elongate member with a nut rotatably assembled onto the threaded section such that the nut can be rotatably advanced along the threaded section but the nut cannot be unscrewed from the elongate member.

4. A self drilling rock bolt according to Claim 3, wherein the nut can be rotatably advanced along the threaded section but the hollow injection sleeve acts as a 20 nut stop and prevents the nut from being unscrewed from the elongate member.

5. A self drilling rock bolt according to any of Claims 1 to 4, wherein the hollow injection sleeve has internal seals or seals that can seal against a male injection nozzle.

6. A self drilling rock bolt according to Claim 5 wherein the hollow injection 25 sleeve has an internal hole which has a larger diameter than the internal hole in the hollow elongate member.

7 A self drilling rock bolt according to any of Claims I to 6, wherein the self drilling rock bolt has a static mixer contained within it.

8. A self drilling rock bolt according to any of Claims 1 to 7, wherein the 30 hollow injection sleeve has an external electrical reading device or devices or electrical contacts on its outer surface which can be electrically connected to remote 28 instrumentation or gauges or monitoring devices contained within or along or on the hollow elongate member.

9. A self drilling rock bolt according to Claim 1, wherein the hollow elongate member is a thick-walled hollow bar where the outside diameter of the hollow 5 elongate member is less than eight times the wall thickness of the hollow elongate member.

10. A self drilling rock bolt according to Claim 1, wherein the hollow elongate member is continuously threaded along all or part of its axial length either with a machined thread, or with a cold rolled thread, or with a hot rolled thread, or with two 10 or more sections of different threads.

11. A self drilling rock bolt according to Claim 10, wherein the hollow elongate member has a threaded section with a relatively fine thread pitch of between 2mm and 6mm at the injection sleeve end of the self drilling rock bolt and on which a nut can be rotatably advanced along the threaded section away from the injection sleeve. 15

12. A self drilling rock bolt according to Claim 1, wherein the hollow elongate member has a hot rolled ribbed profile along all or part of its axial length,