AU2014101163A4 - Ground support device - Google Patents

Abstract

H:\kll\Intrwovn\NRPortbl\DCC\KLL\6804316_ .docx-19/09/2014 Abstract A cable bolt for anchoring in a hole formed in strata by a curable product. The cable bolt includes a central elongate tube defining a throughway through which to pass 5 the curable product, and a plurality of wires that extend spiroidally around the tube. A first set of the wires having a smooth outer surface, and a second set of the wires having grooves and lands formed on the outer surface. The wires are arranged such that each wire of the second set is disposed between two wires of the first set. The lands of wires in the second set contact the smooth outer surface of wires in the first set to form voids 10 between the wires of the first and second sets through which the curable product can flow. 34 34 FIG. 1 34 i

Description

H:\kll\lnterwoven\NRPortbl\DCC\KLL\6804029_1 .DOC-19/09/2014 Ground support device Field of the invention The present invention relates to a ground support device for use in reinforcing rock 5 in areas of strata movement. Background In underground mining and tunnelling situations, rock faces that surround the 10 tunnel can be under significant internal pressures and stresses. As a part of reinforcing and stabilizing the rock against movement, cable bolts are often installed in the rock wall. With appropriate complementary equipment, such as plates and/or mesh sheets, the cable bolts minimize strata movement. 15 Cable bolts are installed by drilling a hole from the rock face into the strata. The cable bolt is then inserted into the hole, and voids between the cable bolt and the rock are filled with a curable product, which is typically grout or resin. The cable bolt can be pre or post-tensioned to provide the required support to the rock wall. 20 The strength of the bond between the cable bolt and the cured product is significant in the working performance of the cable bolt. The strength of the bond is dependent on many factors, including the nature of the curable product and the mechanical interference between the curable product and the components of the cable bolt. 25 There is a need to address or improve the above, and/or at least provide a useful alternative. 30 Summary of the invention The present invention provides a cable bolt for anchoring in a hole formed in strata by a curable product, the cable bolt including: a central elongate tube defining a throughway through which to pass the curable product; H:\kll\lnterovern\NRPortbl\DCC\KLL\6804029_1 .DOC-19/09/2014 -2 a plurality of wires that extend spiroidally around the tube, a first set of the wires having a smooth outer surface, and a second set of the wires having grooves and lands formed on the outer surface, wherein the wires are arranged such that each wire of the second set is disposed 5 between two wires of the first set, and wherein the lands of wires in the second set contact the smooth outer surface of wires in the first set to form voids between the wires of the first and second sets through which the curable product can flow. In some embodiments, the wires of the second set have one or more ribs that 10 each extend in a spiral around and along the outer surface of the respective wire, the radially outer portions of the ribs forming the lands, and the surfaces between the ribs forming the grooves. In some alternative embodiments, each wire of the second set has indentations 15 that form the grooves, and the surfaces of the respective wire between the indentations form the lands. Each indentation can be of a general rhomboid shape. The indentations can be aligned in two or more sets, with each set extending in the elongate direction of the wire. In one exemplary embodiment, the indentations form 20 three longitudinal lands, and generally spiroidal lands that each extend between adjacent pairs of longitudinal lands. The side walls of the spiroidal lands can be curved. The number of wires in the first set is equal to, or greater than the number of wires in the second set. In one exemplary embodiment, cable bolt may have five wires in the 25 first set, and four wires in the second set. The present invention also provides a cable bolt for anchoring in a hole formed in strata by a curable product, the cable bolt including: a central elongate tube defining a throughway through which to pass the curable 30 product; a plurality of wires that extend spiroidally around the tube, wherein the cable bolt has a toe end that in use is to be located adjacent the toe of the hole formed in strata, and a face end that in use is to be located at the face of the strata, and the central elongate tube includes a restrictor that is spaced from the face end, 35 such that a static mixing device can be inserted into the throughway, and the restrictor blocks the static mixing device from further travel along the elongate tube.

H:\kll\lnterwoven\NRPortbl\DCC\KLL\6804029_1 .DOC-19/09/2014 -3 Preferably, cable bolt includes a tensioning member adjacent the face end. In one embodiment, the tensioning member can include a barrel and wedge anchor that locates on the wires and transfers loads from the wires to the surrounding strata and/or other 5 ground support structures. The cable bolt can further include a connector at the face end, the connector including one or more engagement surfaces that a tool can engage to rotate the cable bolt. 10 Preferably, the plurality of wires are secured to the connector. In certain embodiments, the connector has a connector throughway that mates with the face end of the elongate tube such that curable product can be passed through 15 the connector throughway and into the throughway in the elongate tube. The connector can include an internal thread within at least a portion of the connector throughway, such that a nozzle with a complementary external thread can engage the connector whilst introducing curable product. 20 Preferably, the elongate tube includes at least one port in the tube wall such that the curable product fed into the elongate tube can be expelled through or each port. Preferably, the cable bolt further includes a plug that closes the toe end of the 25 elongate tube. In some embodiments, the central elongate tube includes a restrictor that is spaced from the connector such that a static mixing device can be inserted into the throughway, and the restrictor blocks the static mixing device from further travel along the 30 elongate tube. The restrictor can be in the form of one or more indentations in the tube wall that reduce the internal diameter of the elongate tube. The cable bolt can include four indentations that are spaced circumferentially around the elongate tube. 35 H:\kll\lnterovern\NRPortbl\DCC\KLL\6804029_1 .DOC-19/09/2014 -4 In preferred embodiments, the cable bolt includes a plurality of spacers that each surround the central tube, wherein each spacer spaces the plurality of wires radially outwardly of the central tube in a portion of the cable bolt that includes the respective spacer. Preferably, the spacers are evenly distributed along the length of the cable bolt. 5 The present invention also provides a static mixing device for use with a cable bolt that has a central elongate tube, the static mixing device that has a generally elongate cylindrical form, the device comprising a plurality of vanes that extend at least partly in a radial direction of the device, and a support that carries the vanes, whereby curable 10 product that flows past or through the device contacts the vanes and is caused to flow at least partially circumferentially to increase mixing of the curable product. In preferred embodiments, the support includes a central elongate body, and the vanes include a plurality of projections that each project outwardly from the body, 15 wherein the largest diameter of the static mixing device is less than the internal diameter of the elongate tube, wherein the projections space the body from the internal wall of the tube so as to form an annular cavity between the body and the tube wall, and wherein the projections cause curable product to flow at least partially circumferentially as it progresses through 20 the annular cavity to increase mixing of the curable product. Preferably, the cable bolt includes a restrictor that reduces the internal diameter of the elongate tube to a reduced diameter, wherein the reduced diameter is less than the largest diameter of the static mixing device. 25 In some embodiments, at least some of the projections are in the form of an annular segment. Alternatively or additionally, at least some of the projections are in the form of a spiral rib segment. 30 Preferably, the projections are arranged in sets that each extend longitudinally along the central body. In some embodiments, the edges of projections in each set overlaps circumferentially with edges of projections in adjacent sets. In one alternative arrangement, the edges of projections in each set are spaced circumferentially with respect to the edges of projections in adjacent sets. 35 H:\kll\lnterovern\NRPortbl\DCC\KLL\6804029_1 .DOC-19/09/2014 Brief description of the drawings In order that the invention may be more easily understood, embodiments will now be described, by way of example only, with reference to the accompanying drawings, in which: 5 Figure 1: is a side view of a cable bolt according to a first embodiment of the present invention; Figure 2: is a perspective view of the cable bolt of Figure 1, together with a tensioning system and nozzle; Figure 3: is a cross section view of the cable bolt, as viewed along the line Ill-Ill 10 in Figure 1; Figure 4: is an enlarged view of region IV of the cable bolt in Figure 1; Figure 5: is cross section view of a plain wire and an indented wire of the cable bolt of Figure 1; Figure 6: is a side view of the wires, as viewed in the direction of arrow VI in 15 Figure 5; Figure 7: is a cross section view of an indented wire of the cable bolt in Figure 1; Figure 8: is a set of three side views of the indented wire, as viewed along the lines D, E, F in Figure 7; Figure 9: is an end view of the cable bolt, tensioning system and nozzle of 20 Figure 2; Figure 10: is a cross section view of the cable bolt, as viewed along the line X-X in Figure 3; Figure 11: is a perspective view of a static mixer according to a second embodiment of the present invention; 25 Figure 12: is a side view of a cable bolt according to a third embodiment of the present invention; Figure 13: is a perspective view of the cable bolt of Figure 12, together with a tensioning system and nozzle; Figure 14: is a cross section view of the cable bolt, as viewed along the line Ill-Ill 30 in Figure 12; Figure 15: is a side view of a ribbed wire of the cable bolt of Figure 12; Figure 16: is a section view of the ribbed wire of Figure 15; Figure 17: is cross section view of a plain wire and a ribbed wire of the cable bolt of Figure 12; and 35 Figure 18: is a side view of the wires, as viewed in the direction of arrow VI in Figure 17.

H:\kll\lnterwoven\NRPortbl\DCC\KLL\6804029_1 .DOC-19/09/2014 -6 Detailed description Figures 1 to 4 show a cable bolt 10 according to a first embodiment of the present 5 invention. The cable bolt 10 has a central elongate tube 12 that defines a throughway 14 through which to pass the curable product. A plurality of wires extend spiroidally around the tube 12. A first set 16 of the wires have a smooth outer surface, and a second set 18 of the wires having grooves 20 and lands 22 formed on the outer surface. The wires 16, 18 are shown in further detail in Figures 4 to 8. 10 In the cable bolt 10, the wires 16, 18 are arranged such that each wire of the second set 18 is disposed between two wires of the first set 16. Accordingly, where the lands 22 of wires in the second set 18 contact the smooth outer surface of wires in the first set 16 to form voids V between the wires of the first and second sets 16, 18 through 15 which the curable product can flow. This arrangement is illustrated in Figure 6. As will be appreciated, the cable bolt 10 is formed by aligning wires 16, 18 in a direction parallel to the tube 12, and subsequently twisting the wires to form the spiral shape. This twisting operation forces wires 16, 18 against one another. By ensuring that voids are formed between contacting wires 16, 18, a curable product, such as resin or grout, can flow into 20 the voids V. When the product is cured, engagement between the product and the cable bolt 10 can be enhanced, which can provide for improved performance. A wire 18 of the second set is shown in detail in Figures 7 and 8. As shown particularly in Figure 8, the wire 18 has indentations that form the grooves 20. Each 25 groove 20 has a general rhomboid shape. The surfaces of the wire 18 between the grooves 20 form the lands 22. In this particular embodiment, the grooves 20 are aligned in three sets, with each set extending in the elongate direction of the wire 18. The lands 22 consist three longitudinal lands 22a, 30 and generally spiroidal lands 22b that each extend between adjacent pairs of longitudinal lands 22a. As shown in Figure 8, the side walls of the spiroidal lands 22b are curved. Figure 10 shows the cable bolt 10 in cross section, as viewed along the line X-X in Figure 3. The cable bolt 10 has nine (9) wires, of which five (5) are wires in the first set 35 16, and four (4) are wires in the second set 18.

H:\kll\lnterwoven\NRPortbl\DCC\KLL\6804029_1 .DOC-19/09/2014 -7 The cable bolt 10 has a toe end 24 that, in use, is to be located the toe of a hole formed in strata, and a face end 26 that in use is to be located at the face of the rock, and the cable bolt 10 can be used in combination with a tensioning member adjacent the face end 26. The tensioning member can include a barrel 28 and wedge segments 30 (shown 5 in Figures 2 and 9) that locate on the wires 16, 18 adjacent the face end 26. The barrel 28 and wedge segments 30 transfer loads from the wires to the surrounding strata. Barrel and wedge anchor systems will be familiar to the person skilled in the art, and are not described in further detail. 10 The cable bolt 10 includes a connector 32 at the face end 26, with the wires 16, 18 being secured to the connector 32. The connector 32 has engagement surfaces 34 that a tool can engage to rotate the cable bolt 10. As shown most clearly in Figure 3, the connector 32 defines a connector throughway 36 that mates with the face end of the elongate tube 12. Accordingly, curable product can be passed through the connector 15 throughway 36 and into the throughway 14 in the elongate tube 12. A port 38 is formed in wall of the elongate tube 12, such that the curable product can exit the elongate tube 12. In some embodiments, the port 38 can be one of several ports. Alternatively or additionally, the port, or at least one of the ports, can be formed in an end plug 40 that closes the toe end of the elongate tube 12. 20 A portion of the connector throughway 36 is internally threaded, such that a nozzle N with a complementary external thread can engage the connector 32 whilst introducing curable product. The nozzle N forms part of a delivery system for supplying curable product (such as grout or resin) to the cable bolt 10. 25 The central elongate tube 12 includes a restrictor that is spaced from the connector 32. A static mixing device can be inserted into the throughway 14, and the restrictor blocks the static mixing device from further travel along the elongate tube 12. The static mixing device is described in further detail below in reference to Figure 11. In 30 this embodiment, the restrictor is in the form of indentations 42 in the wall of the tube 12 that reduce the internal diameter of the tube 12. The cable bolt 10 has four indentations 42 that are spaced circumferentially around the elongate tube 12. The cable bolt 10 includes spacers 44 that each surround the tube 12, and space 35 the wires 16, 18 radially outwardly of the tube 12. This causes the wires 16, 18 to spread radially to form a "bulb" in a portion of the cable bolt 10 that includes each spacer 44. In H:\kll\lnterovern\NRPortbl\DCC\KLL\6804029_1 .DOC-19/09/2014 -8 one example, each spacer 44 is in the form of a ring with radially projecting ribs that define channels. Each wire 16, 18 sits within a channel, and between two ribs, at the meeting point of the respective wire and spacer 44. Preferably, the spacers are evenly distributed along the length of the cable bolt 10. 5 In portions of the cable bolt 10 between the spacers 44, the wires 16, 18 are in contact with the tube 12. A sleeve 46 is provided at the toe end of the cable bolt 10. The sleeve 46 is 10 swaged onto the wires 16, 18 to secure the wires 16, 18 in place at the toe end of the cable bolt 10. Figure 11 shows a static mixing device 50 that is suitable for use with the cable bolt 10 of Figures 1 to 4. The static mixing device 50 has a central body 52, and a 15 plurality of projections 54 that each project outwardly from the body 52. The largest diameter of the static mixing device 50 is less than the internal diameter of the elongate tube 12; that is, the diameter of the throughway 14. The projections 54 space the body 52 from the internal wall of the tube 12, which forms an annular cavity between the body 52 and the tube 12. 20 In use, the mixing device 50 is inserted through the connector 32, and into the throughway 14 in the tube 12. Passage of the mixing device 50 through the throughway 14 is limited by the restrictor. In particular, passage of the mixing device 50 is blocked by the abutment of projections 54 against the indentations 42. Further, curable product 25 flowing through the throughway 14 must flow around the mixing device, and through the annular cavity. The projections 54 cause curable product to flow at least partially circumferentially as it progresses through the annular cavity, and this enhances mixing of the curable product. This is particularly advantageous because a homogeneous curable product is likely to cure with maximum engagement with the cable bolt and surrounding 30 strata. In the embodiment of Figure 11, the projections 54 are each in the form of an annular segment. The projections 54 are arranged in four sets, with each set extending longitudinally along the central body 52. Each projection 54 extends less than one 35 quarter of the outer circumference of the body 52. Accordingly, the circumferential edges H:\kll\lnterovern\NRPortbl\DCC\KLL\6804029_1 .DOC-19/09/2014 -9 of the projections 54 are spaced circumferentially with respect to the edges of projections in adjacent sets. Figures 12 to 18 show a cable bolt 110 according to a second embodiment of the 5 present invention. The cable bolt 110 is substantially similar to the cable bolt 10 of Figure 1. In Figures 12 to 18, the features of the cable bolt 110 that are substantially similar to those of the cable bolt 10 have the same reference numeral with the prefix "1". The primary difference between the cable bolts 10, 110 of the illustrated 10 embodiments is that the wires of the second set 118 in the cable bolt 110 each have ribs that each extend in a spiral around and along the outer surface of the respective wire. One of the wires of the second set 118 is illustrated in Figures 15 and 16. The radially outer portions of the ribs form lands 122, and the surfaces between the ribs form the grooves 120. As is evident from Figure 16, each wire 118 has four ribs. 15 The wires 116, 118 are arranged in the cable bolt 110 such that each wire of the second set 118 is disposed between two wires of the first set 116. As shown in Figure 18, where the lands 122 of wires in the second set 118 contact the smooth outer surface of wires in the first set 116, voids V are formed through which the curable product can flow. 20 The invention has been described in reference to the drawings by way of non limiting examples only, and many modifications and variations may be made thereto without departing from the spirit and scope of the invention. 25 In one alternative embodiment, a cable bolt at least partially in accordance with Figure 1 may be provided in which the wires of the second set have narrow grooves formed in the outer surface. In these wires, the lands between the grooves may be wider than the grooves. The grooves can extend spiroidally around the outer surface of the respective wires. 30 In another alternative embodiment, a cable bolt at least partially in accordance with Figure 1 may be provided in which all the wires have narrow grooves formed in the outer surface, as described above.

H:\kll\lnterovern\NRPortbl\DCC\KLL\6804029_1 .DOC-19/09/2014 -10 In another alternative embodiment, a cable bolt at least partially in accordance with Figure 1 may be provided in which all the wires have smooth outer surface, and also include a restrictor in the central tube.

Claims (20)

1. A cable bolt for anchoring in a hole formed in strata by a curable product, the cable bolt including: 5 a central elongate tube defining a throughway through which to pass the curable product; a plurality of wires that extend spiroidally around the tube, a first set of the wires having a smooth outer surface, and a second set of the wires having grooves and lands formed on the outer surface, 10 wherein the wires are arranged such that each wire of the second set is disposed between two wires of the first set, and wherein the lands of wires in the second set contact the smooth outer surface of wires in the first set to form voids between the wires of the first and second sets through which the curable product can flow. 15

2. A cable bolt according to claim 1, wherein the wires of the second set have one or more ribs that each extend in a spiral around and along the outer surface of the respective wire, the radially outer portions of the ribs forming the lands, and the surfaces between the ribs forming the grooves. 20

3. A cable bolt according to claim 1, wherein each wire of the second set has indentations that form the grooves, and the surfaces of the respective wire between the indentations form the lands.

4. A cable bolt according to claim 3, wherein the indentations form three longitudinal 25 lands, and generally spiroidal lands that each extend between adjacent pairs of longitudinal lands.

5. A cable bolt according to any one of claims 1 to 4, wherein the number of wires in the first set is equal to, or greater than the number of wires in the second set. 30

6. A cable bolt according to any one of claims 1 to 5, wherein the cable bolt has five wires in the first set, and four wires in the second set.

7. A cable bolt for anchoring in a hole formed in strata by a curable product, the 35 cable bolt including: H:\kll\lnterovern\NRPortbl\DCC\KLL\6804029_1 .DOC-19/09/2014 -12 a central elongate tube defining a throughway through which to pass the curable product; a plurality of wires that extend spiroidally around the tube, wherein the cable bolt has a toe end that in use is to be located adjacent the toe of 5 the hole formed in strata, and a face end that in use is to be located at the face of the strata, and the central elongate tube includes a restrictor that is spaced from the face end, such that a static mixing device can be inserted into the throughway, and the restrictor blocks the static mixing device from further travel along the elongate tube. 10

8. A cable bolt according to any one of claims 1 to 7, further including a tensioning member adjacent the face end.

9. A cable bolt according to any one of claims 1 to 8, further including a connector at the face end, the connector including one or more engagement surfaces that a tool can 15 engage to rotate the cable bolt.

10. A cable bolt according to claim 9, wherein the plurality of wires are secured to the connector. 20

11. A cable bolt according to either claim 9 or 10, wherein the connector has a connector throughway that mates with the face end of the elongate tube such that curable product can be passed through the connector throughway and into the throughway in the elongate tube. 25

12. A cable bolt according to any one of claims 9 to 11, wherein the connector includes an internal thread within at least a portion of the connector throughway, such that a nozzle with a complementary external thread can engage the connector whilst introducing curable product. 30

13. A cable bolt according to any one of claims 1 to 12, wherein the central elongate tube includes at least one port in the tube wall such that the curable product fed into the elongate tube can be expelled through or each port.

14. A cable bolt according to any one of claims 1 to 13, further including a plug that 35 closes the toe end of the elongate tube. H:\kll\lnterwoven\NRPortbl\DCC\KLL\6804029_1 .DOC-19/09/2014 -13

15. A cable bolt according to any one of claims 1 to 14, wherein the central elongate tube includes a restrictor that is spaced from the connector such that a static mixing device can be inserted into the throughway, and the restrictor blocks the static mixing device from further travel along the elongate tube. 5

16. A cable bolt according to claim 15, wherein the restrictor is in the form of one or more indentations in the tube wall that reduce the internal diameter of the elongate tube.

17. A cable bolt according to any one of claims 1 to 16, further including a plurality of 10 spacers that each surround the central tube, wherein each spacer spaces the plurality of wires radially outwardly of the central tube in a portion of the cable bolt that includes the respective spacer.

18. A static mixing device for use with a cable bolt that has a central elongate tube, 15 the static mixing device that has a generally elongate cylindrical form, the device comprising a plurality of vanes that extend at least partly in a radial direction of the device, and a support that carries the vanes, whereby curable product that flows past or through the device contacts the vanes and is caused to flow at least partially circumferentially to increase mixing of the curable product. 20

19. A static mixing device according to claim 18, wherein: the support includes a central elongate body, and the vanes include a plurality of projections that each project outwardly from the body, the largest diameter of the static mixing device is less than the internal diameter of 25 the elongate tube, the projections space the body from the internal wall of the tube so as to form an annular cavity between the body and the tube wall, and the projections cause curable product to flow at least partially circumferentially as it progresses through the annular cavity to increase mixing of the curable product. 30

20. A static mixing device according to claim 19, wherein at least some of the projections are in the form of an annular segment.