AUSTRALIA PATENTS ACT 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT ORIGINAL Name of Applicant/s: Jennmar Australia Pty Ltd Actual Inventor/s: Tony Steains Address for Service: Baldwin Shelston Waters 60 MARGARET STREET SYDNEY NSW 2000 CCN: 3710000352 Invention Title: CABLE BOLT The following statement is a full description of this invention, including the best method of performing it known to me/us: File: 40848AUP00 -la FIELD OF THE INVENTION The present invention relates to tensionable cable bolts suitable for cement grouted applications and in particular to tensionable cable bolts that are resin anchored prior to tensioning, tensioned, then post grouted with cement. However, it will be 5 appreciated that the invention is not limited to this particular field of use and may also be applicable to other applications where an improved point anchor system is desirable. BACKGROUND OF THE INVENTION Any discussion of the prior art throughout the specification should in no way be considered as an admission that such prior art is widely known or forms part of the 10 common general knowledge in the field. I(nown methods for reinforcing rock faces include the use of tensionable cable bolts that are configured to allow post tensioning grouting of the cable into a bore hole. These cable bolts are usually made from a plurality of steel filaments wound together to form a tendon. These tendons may also have a number of uniformly sized deformations 15 in the form of, for example, "bulbs", "cages", "buttons"(steel sleeves), "swages" (rings or barrels that lock onto the cable using tapered cable gripping wedge elements) or other deformations along the length of the cable to provide improved anchorage and load transfer between the cable and the resin or cement grout and the strata. "Bulbs" or "cages" are formed by deforming at least some of the cable filaments so that they extend 20 radially outwardly from the rest of the cable periphery. "Buttons" (steel sleeves) and "swages" are respectively crimped on and pressed on to the plain cable. To facilitate post grouting of these types of cables, the bore holes must be over sized to thereby enable a breather tube and/or a grout tube to be inserted into the hole alongside the bolt and to allow the grout to flow freely into the bore. However, prior to 2 installing the cement grout, the cable bolt is first point anchored with resin at the furthermost end of the bore. Point anchoring is achieved by locating a resin cartridge(s) in the closed end of the bore and then inserting and rotating the cable bolt to burst the resin cartridge(s) and 5 mix it's contents after which the mixed resin is allowed to cure. Once the resin is sufficiently set, the bolt is tensioned and cement grout can then be inserted, as required, in the remainder of the bore. Typically this is done by either inserting a grout tube to a location just below the point anchor so the grout enters from the top and displaces the air in the bore, or alternatively by filling from the end by inserting grout from adjacent the 10 bore opening and displacing the air in the bore via a breather tube that has an opening just below the point anchor. One of the disadvantages of these prior art systems is that the size of the uniform deformations are small relative to the bore diameter to allow the air breather tube or grout tube to pass between the bore and the cable. This results in poor mixing of the 15 resin which has the effect of not only compromising the strength effectiveness of the point anchor but also increases the chance of mixed or unmixed resin remaining in the bore which can leak downwards and block the breather or grout tubes. One variation of the above prior art includes a cable having a plurality of large deformations along a point anchor section of pre-determined length and plain cable for 20 the grouted section with a resin retaining washer device affixed to the cable to form a divider between the two sections. While the effectiveness of the point anchor may be improved, this prior art has the disadvantage that the cement grouting does not bond as well with the straight cable, hence the load transfer and pull out strength effectiveness of the cable as a whole is reduced.
3 Furthermore, variations in the rock strata at different bore locations may necessitate the use of more resin and a longer length of point anchor to ensure adequate keying with the rock strata prior to the tensioning and post grouting operations. In such cases the resin retaining washer actually hinders the insertion and s mixing process and fails to assist in retaining resin along the full length of the anchor region. Again any resin leaking into the groutable section may cause a blockage in the air breather/grout tube making it difficult to completely fill the remainder of the bore with cement, hence the cable may be insecurely embedded in the cement grout and the installation integrity further undermined. 10 It is an object of the present invention to overcome or ameliorate at least one or more of the disadvantages of the prior art, or at least to provide a useful alternative. DISCLOSURE OF THE INVENTION According to a first aspect there is provided a resin anchorable cable bolt adapted for use in pre-tensioned cement post grouting applications in a suitably sized 15 bore, said cable bolt including: a cable formed from a plurality of wound coextending steel filaments, said cable having at one end a first portion adapted primarily for resin point anchoring and a second portion adapted predominantly for cement grouting, wherein said first portion include one or more resin mixing protrusions that extend radially outwardly therefrom, and said second portion includes one or more grout 20 engagable protrusions that extend radially outwardly therefrom; and a resin retaining collar assembly releasably engagable with said cable at a selected region between said first portion and said second portion for substantially reducing the migration of resin from said first portion to said second portion within said bore; wherein said resin mixing protrusions of said first portion extend radially outwardly further than said 25 grout engagable protrusions of said second portion such that the cable bolt is configured so that an air breather tube or grout tube may be inserted to a position just below said resin retaining collar assembly between said second portion of the cable and said bore. The term resin mixing protrusion is not intended to limit the function of this 30 feature to resin mixing, as it is clear that such protrusions also have the function of improving load transfer between the bolt and the resin. 25044_2 (GhMattrs) P0C226AU 4 As discussed above, the resin mixing protrusions of the first portion extend radially outwardly further than the grout engagable protrusions of the second portion. This facilitates use of an air breather/grout tube in the second portion while increasing the surface area of the cable coming in contact with the resin in the first portion, hence a providing substantially more secure anchorage with the bore. In one embodiment of the invention, the resin mixing protrusions are in the form of "bulbs" formed by spacing apart and forcing outwardly all of the steel filaments around the periphery of the cable. The grout engagable protrusions may also be in the form of "bulbs". Preferably, the "bulbs" include means for retaining the bulb a0 shape under tensile loads such as ball bearings or any solid object enclosed within the steel filaments of the bulbs. In a second embodiment of the invention, the resin mixing protrusions in the first portion are in the form of "bulbs" formed by spacing apart and forcing outwardly all of the steel filaments around the periphery of the cable. The grout engagable i5 protrusions in the second portion are a plurality of spaced "buttons" (steel sleeves) crimped along that length of the cable, In a third embodiment of the invention the resin mixing protrusions in the first portion are spaced "buttons"(steel sleeves). The grout engagable protrusions in the second portion may also be a plurality of spaced "buttons" (steel sleeves) crimped 20 along that length of the cable. In a fourth embodiment of the invention, the resin mixing protrusions in the first portion are in the form of "nut cages" each having one or more nuts spaced along one or more central steel filaments with the remaining filaments wrapped around the periphery of the nut such that the nut is encased within a cage formed by the remaining 25 steel filaments. The grout engagable protrusions in the second portion may also be in the form of "nut cages". In a fifth embodiment of the invention, the grout engagable protrusions in the second portion are a plurality of spaced "buttons" (steel sleeves) crimped along the length of the cable adapted to suspend an air breather tube or grout tube just below the 30 resin retaining collar assembly. 204M4J (GH Mtter) PnMf.AU 5 It will be appreciated that while preferred combinations of protrusions are discussed above the invention is not limited to these particular embodiments and is equally applicable to different combinations of resin mixing and grout engagable protrusions not specifically disclosed herein. 5 Preferably, the releasably engagable resin retaining collar assembly is adapted for connection to the cable in a radial direction thereby avoiding the need to slide the collar onto the cable. In one preferred form the collar has a split configuration and comprises a pair of mutually opposed lockingly engagable annulus halves adapted for clamping connection to the cable. 10 More preferably, the annulus halves are hinged at one side and include locking means provided at the side remote therefrom. The fastening means preferably comprises one or more captively retained screws. In another aspect, there is provided a method of installing a cable bolt into rock is strata, the cable bolt being formed from plurality of wound coextending steel filaments and having a first portion adapted primarily for resin point anchoring and including one or more resin mixing protrusions, a second portion adapted for cement grouting and including one or more grout engagable protrusions, the resin mixing protrusions extending radially outwardly further than the grout engagable protrusions, and a resin 20 retaining collar disposed on the cable between the first and second portions, the method comprising the steps of: drilling a bore in the rock strata; inserting one or more resin cartridges into a closed end of the bore in the rock strata; inserting the cable bolt into the bore and nanoeuvring the cable bolt therein so as to cause the one or more resin cartridges to burst, the resin retained in the bore by the resin retaining collar; 25 disposing an air breather or grout tube into the bore over the grout engagable protrusions; mixing the resin by rotation of the resin mixing protrusions in the bore and allowing the resin to cure so as to point anchor the cable bolt; and subsequently tensioning the cable bolt without causing straightening of the grout engagable protrusions. c In one form, the grout engagable protrusions are in the form of bulbs formed by spacing apart and forcing outwardly all of said steel filaments around the periphery of 2504WL43 (KiHMItlI) PV2D-A U Sa the cable, and including bal bearings or any solid objects enclosed within said steel filaments of said bulbs, and wherein on tensioning of the cable, the ball bearings or solid objects enclosed within the steel filaments prevent the bulbs from straightening out. s In one form of the method further comprises the steps of: providing the cable bolt with the air breather or grout tube affixed to the cable in a position wherein that tube extends over the grout engagable protrusions; and inserting the cable bolt with the air breather or grout tube into the bore. In one form, the method further comprises the step of adjusting the position of io the resin retaining collar assembly on the cable prior to inserting the cable bolt into the bore. 2004104,3 (GH MtEr) P22M AU 6 BRIEF DESCRIPTION OF THE DRAWINGS A preferred embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings in which: Figure 1 is a sectional side view of an installed first embodiment of a cable bolt 5 according to the invention, having large bulbs in the first portion and relatively smaller bulbs in the second portion; Figure 2 is a sectional side view of an installed second embodiment of a cable bolt according to the invention, having large bulbs in the first portion and crimped "buttons"(steel sleeves) in the second portion; 10 Figure 3 is a sectional side view of an installed third embodiment of a cable bolt according to the invention, having large crimped "buttons"(steel sleeves) in the first portion and relatively smaller crimped "buttons"(steel sleeves) in the second portion; - Figure 4 is a sectional side view of an installed fourth embodiment of a cable bolt according to the invention, having "nut cages" in the first portion and crimped 15 "buttons"(steel sleeves) in the second portion; Figure 5 is a sectional side view of an installed fifth embodiment of a cable bolt according to the invention, having enlarged bulbs in the first portion and modified perforated crimped "buttons"(steel sleeves) suspending an air breather/grout tube in the second portion; 20 Figure 6a is an enlarged side view of a resin retaining collar assembly according to the invention; Figure 6b is a plan view of the resin retaining collar assembly with a partial cross-section taken on line B-B of Figure 6a; and Figure 6c is a side view of the resin retaining collar assembly with a partial 25 cross-section taken on line C-C of Figure 6b.
7 PREFERRED EMBODIMENT OF THE INVENTION Referring to the drawings, the resin anchorable cable bolts of the invention each include a cable 1 formed from a plurality of spiral wound coextending steel filaments. 5 The cable has at one end a first portion 2 adapted primarily for resin point anchoring and a second portion 3 adapted predominantly for cement grouting. The first portion includes one or more resin mixing protrusions 4 that extend radially outwardly therefrom. A releaseable resin retaining collar assembly 5 is engaged with the cable 1 at a selected region between the first portion 2 and the second portion 3 for substantially 10 reducing the migration of resin from the first portion to the second portion within a bore 6. In all the embodiments of the invention shown in Figures 1 to 5, the second portion 3 includes one or more grout engagable protrusions 7 that extend radially outwardly. These are sized and configured such that an air breather tube or grout tube 8 15 may be inserted into a position just below the resin retaining collar assembly 5 between the second portion of the cable 1 and the bore 6, as seen in Figure 1. Further clearance is also preferably provided to allow free flow of the grout past the protrusions 7. Figure 1 also shows an embodiment of the invention where the resin mixing protrusions 4 of the first portion 2 extend radially outwardly further than the grout engagable protrusions 7 20 of the second portion 3. These resin mixing and grout engaging protrusions may take many different forms including "bulbs", "nut cages", steel "swages" and crimped "steel sleeves" known in the trade as "buttons". "Bulbs" 9, as seen in Figures 1, 2 and 5, are formed by spacing apart and forcing 25 outwardly all of the steel filaments around the periphery of the cable 1. Both the resin 8 mixing protrusions 4 in the first portion 2 and the grout engagable protrusions 7 in the second portion 3 may be in the form of bulbs. The bulbs may also include means for retaining the bulb shape under tensile loads, such as a ball bearing or any solid object 10 enclosed within the steel filaments of the bulbs, as seen in second portion of Figure 1. 5 In another embodiment (not illustrated) the bulbs are initially formed in identical size along the full length and radially extending sleeves or other attachments are connected to the bulbs at the first end. "Nut cages" as used in the first portion 2 of Figure 4, are formed by unwinding the steel filaments of the cable 1, and sliding a nut 11 along one or more central steel 10 filaments. The remaining filaments are then wrapped around the periphery of the nut, encasing it within a cage formed by the remaining steel filaments. Both the resin mixing protrusions 4 in the first portion 2 and the grout engagable protrusions 7 in the second - portion 3 may be in the form of "nut cages". Alternatively, crimped "buttons"(steel sleeves) may form the grout engagable 15 protrusions 7 on the second portion 3 as seen in Figure 4. These are formed by crimping a plurality of spaced steel sleeves 12 securely along the length of the cable 1. The crimped "buttons"(steel sleeves) may also be in the form of perforated "buttons"(steel sleeves) 13 adapted to suspend an air breather tube or grout tube 8 just below the resin retaining collar assembly 5, as seen in Figure 5. 20 Alternatively, crimped "buttons"(steel sleeves) may form the resin mixing protrusions 4 in the first portion 2 and the grout engagable protrusions 7 in the second portion 3 as seen in Figure 3. Alternatively, pressed on "swages" may form the resin mixing protrusions in the first portion 2 and the grout engagable protrusions in the second portion 3.
9 The preferred form of the releasably engagable resin retaining collar assembly 5 comprises a pair of mutually opposed lockingly engagable annulus halves 14, as seen in Figures 6a, 6b and 6c. The annulus halves may be hingedly connected at one side and include locking means provided at the side remote therefrom. A fastening means such 5 as one or more captively retained screws 15 may be used to secure the annulus halves together. However, it will be appreciated by those skilled in the art that many variations of collars with releasable fastening means may be utilised. In use, a bore is drilled into the rock strata and a point anchor is established. This is achieved by inserting resin cartridge(s) in the closed end of the bore. The 10 amount of resin required will depend on the analysis of the rock strata on site. Therefore, it may be necessary to move the resin retaining collar assembly 5 along the cable in order to allow for extra resin and reduce the risk of overflow from the first portion into the second portion. The cable 1 is then introduced into the bore 6 so that the first portion 2 comes in 15 contact with the resin cartridge(s). Further insertion and rotation of the bolt then bursts the cartridge(s) and the enlarged protrusions 4 contribute to effective mixing and curing of the resin. The cable 1 is then tensioned. Where "bulbs" are used as the grout engagable protrusions 7 in the second portion 3, items such as ball bearings or any solid object 10 enclosed within the steel filaments prevent the "bulbs" from straightening out 20 during this process. Depending on the application, it may be necessary or at least desirable to cement grout the remainder of the bore. This is achieved by inserting an air breather or grout tube 8 to a location just below the resin retaining collar assembly 5, so the grout displaces the air in the bore, or alternatively by inserting grout from adjacent the bore 10 opening and displacing the air in the bore via a breather tube that has an opening just below the resin retaining collar assembly. Alternatively, perforated "buttons"(steel sleeves) such as those seen in the second portion of Figure 5 may be used to allow an air breather tube or grout tube 8 to s be inserted with the bolt during the point anchoring process in order to maximise time efficiency. It will be appreciated that the illustrated cable bolt substantially reduces the risk of resin migrating from the first portion to the second portion of the bore, thereby keeping the air breather/grout tube significantly free of resin and allowing the second 10 portion to be effectively grouted. Furthermore, the increased size of the deformations in the first portion in comparison to the second portion may provide improved anchorage in the point anchor. Additionally, the releasably engagable resin retaining collar enables the cable bolt to be conveniently adapted for use in varying rock strata conditions. IS Although the invention has been described with reference to specific examples, it will be appreciated by those skilled in the art that the invention may be embodied in many other forms, For example, the second cement groutable portion of the cable may be plain. Similarly, the formations formed in either portion of the cable may be made by methods other than those described herein. 20 It is to be understood that, if any prior art publication is referred to herein, such reference does not constitute an admission that the publication forms a part of the common general knowledge in the art, in Australia or any other country. In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary 25 implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention, 0004-2 { MM .hi-) W28l.AU