AU2008202980A1 - Yielding rock bolt - Google Patents
Yielding rock bolt Download PDFInfo
- Publication number
- AU2008202980A1 AU2008202980A1 AU2008202980A AU2008202980A AU2008202980A1 AU 2008202980 A1 AU2008202980 A1 AU 2008202980A1 AU 2008202980 A AU2008202980 A AU 2008202980A AU 2008202980 A AU2008202980 A AU 2008202980A AU 2008202980 A1 AU2008202980 A1 AU 2008202980A1
- Authority
- AU
- Australia
- Prior art keywords
- yielding
- sleeve
- rock bolt
- elongated member
- yielding portion
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
- 239000011435 rock Substances 0.000 title claims description 54
- 230000007423 decrease Effects 0.000 claims description 5
- 239000011440 grout Substances 0.000 description 12
- 230000006835 compression Effects 0.000 description 6
- 238000007906 compression Methods 0.000 description 6
- 238000000034 method Methods 0.000 description 4
- 230000000694 effects Effects 0.000 description 3
- 125000006850 spacer group Chemical group 0.000 description 3
- 229910000831 Steel Inorganic materials 0.000 description 2
- 238000004873 anchoring Methods 0.000 description 2
- 230000008878 coupling Effects 0.000 description 2
- 238000010168 coupling process Methods 0.000 description 2
- 238000005859 coupling reaction Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 239000011347 resin Substances 0.000 description 2
- 229920005989 resin Polymers 0.000 description 2
- 239000010959 steel Substances 0.000 description 2
- 239000004593 Epoxy Substances 0.000 description 1
- 230000004888 barrier function Effects 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 125000003700 epoxy group Chemical group 0.000 description 1
- 239000003292 glue Substances 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 238000005065 mining Methods 0.000 description 1
- 238000012856 packing Methods 0.000 description 1
- 229920000647 polyepoxide Polymers 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000003466 welding Methods 0.000 description 1
Classifications
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D21/00—Anchoring-bolts for roof, floor in galleries or longwall working, or shaft-lining protection
- E21D21/0026—Anchoring-bolts for roof, floor in galleries or longwall working, or shaft-lining protection characterised by constructional features of the bolts
- E21D21/0033—Anchoring-bolts for roof, floor in galleries or longwall working, or shaft-lining protection characterised by constructional features of the bolts having a jacket or outer tube
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D21/00—Anchoring-bolts for roof, floor in galleries or longwall working, or shaft-lining protection
- E21D21/008—Anchoring or tensioning means
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D21/00—Anchoring-bolts for roof, floor in galleries or longwall working, or shaft-lining protection
- E21D21/02—Anchoring-bolts for roof, floor in galleries or longwall working, or shaft-lining protection having means for indicating tension
Landscapes
- Engineering & Computer Science (AREA)
- Mining & Mineral Resources (AREA)
- Structural Engineering (AREA)
- Life Sciences & Earth Sciences (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Geology (AREA)
- Devices Affording Protection Of Roads Or Walls For Sound Insulation (AREA)
Description
AUSTRALIA
Patents Act 1990 COMPLETE SPECIFICATION Standard Patent Applicant(s): Fero Group Pty Ltd Invention Title: YIELDING ROCK BOLT The following statement is a full description of this invention, including the best method for performing it known to me/us: P75OO3AU.1 PaLSeltFiing Appliation 2008-7.4 doe (P) 00 -2 O Field of the Invention The present invention relates to a rock bolt particularly, although not exclusively, for use in supporting a rock face.
00 0 Background of the Invention CI Rock bolts are commonly used in mining and civil 00 construction to support a rock face. A typical rock bolt comprises an elongate member that is placed in a hole drilled through the rock face into a body of rock and subsequently adhered to the rock by grout or resin. An end of the elongate member extends beyond the rock face and is clamped to the rock face. In the event of a fracture occurring in the body of rock at a location along the length of the elongated member, the rock bolt can act to support the fractured portion of rock between the rock face and the fracture preventing it from falling and potentially injuring or killing workers or damaging the equipment. It is also known for rock bolts to incorporate members or structures that yield in response to a load applied to the elongate member arising from the fracturing of the rock. Force applied to the elongate member as a result of energy released by for example a rock burst is transferred from the elongate member to the structure which yields to absorb the energy.
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.
N:kPerthkCasesNPatent\75000-75999P75903AU. 1 SpeciskP75903AU 1 Specification 2008-7-3 doc 3107108 00 Summary of the Invention c-s According to one aspect of the present invention there is provided a yielding rock bolt comprising: a yielding portion having a longitudinal axis, the yielding portion configured to concertina in a direction 00 along the longitudinal axis in response to a force applied I' to the yielding portion in a direction parallel to the 00 longitudinal axis.
00 ^In one embodiment, the bolt is configured so that the yielding portion concertinas in a manner to increase in length along the longitudinal axis.
However in an alternate embodiment, the rock bolt is configured so that the yielding portion concertinas in a direction to decrease in length along the longitudinal axis.
The rock bolt may further comprise a sheath disposed about the yielding portion and within which the yielding portion can concertina in response to the applied force.
In one embodiment, the yielding rock bolt comprises a sleeve having opposite first and second ends wherein the yielding portion is a portion of the sleeve.
The yielding rock bolt may further comprise an elongated member extending through the sleeve and beyond the first and second ends of the sleeve, wherein the elongate member is attached to the sleeve in a manner wherein a force applied to the elongated member is transferred to the sleeve.
In one form of the invention the elongated member is attached to the sleeve at a location where a tensile force applied to the elongated member is transferred as a N:\Perth\Cases\Patent\75000-75999\P75903.AU 1\Specis\P75903AU.1 Specfication 2008-7-3.doc 3/07/08 00 Stensile force on the yielding portion. However in an alternate embodiment, the elongated member is attached to the sleeve at a location where a tensile force applied to the elongated member is transferred as a compressive force s on the yielding portion.
00 In one embodiment, the yielding portion comprises at least (Ni a portion of a length of the sleeve formed with a wall (1 that is configured so that a transverse distance between 00 the longitudinal axis of the sleeve and the wall sequentially increases and decreases in a direction along the longitudinal axis. Thus, when the sleeve is in the from of a cylindrical tube, the yielding portion may be realised by at least a part of the length of the tube having a wall that is shaped so that the internal radius of the wall sequentially increases and decreases in the direction of the longitudinal axis.
In these embodiments, the yielding portion is able to concertina by virtue of either axial compression or axial extension. In an alternate embodiment, the yielding portion comprises a plurality of slots or cuts formed in a wall of the sleeve about the longitudinal axis forming a series of circumferentially spaced links which are able to fold in response to the application of a compressive force.
In yet another embodiment, the yielding rock bolt comprises an elongated member wherein the yielding portion comprises a length of the elongated member formed with a plurality of bends that traverse a longitudinal axis of the elongated member.
P75 lSpecis\P75903.AU.1 Speification 2008-7-3.doc 3107108 00 00 O Brief Description of the Drawings
Z
The embodiments of the present invention will now be described by way of example only with reference to the accompanying drawings in which: 00 0 Figure 1 is a schematic representation of a first (Ni embodiment of a yielding rock bolt in accordance with the 00 present invention; 00 Figure 2 is a schematic representation of a yielding rock bolt installed in a body of rock; Figures 3a and 3b illustrate alternate states of a second embodiment of the yielding rock bolt; and Figure 4 is a schematic representation of a third embodiment of the yielding rock bolt.
Description of the Preferred Embodiments Figures 1 and 2 depict a first embodiment of a yielding rock bolt 10 (hereinafter referred to in general as "bolt comprising a yielding portion 12 having a longitudinal axis 14, the portion 12 configured to concertina in a direction along the longitudinal axis 14 in response to a force applied to the yielding portion 12 in a direction parallel to the axis 14.
The word "concertina" when used as a verb in this specification is intended to denote axial extension or axial compression of a yielding portion 12 facilitated by a folding or unfolding of the yielding portion.
With particular reference to Figure 1, it can be seen that the yielding portion 12 is a portion of a sleeve 16 having a wall 18 which is configured as a series of corrugations in the axial direction. Thus, viewing the sleeve 16 in the transverse section as shown in Figure 1, a transverse distance or radius R from the longitudinal axis 14 to an N:PerthCases\Patent75000-75999\P75903.AU 1\Specis\P75903.AU 1 Speification 2008-7-3doc 3/07/08 00 -6 0 interior surface of the wall 18 varies from a maximum R1 to a minimum R2 in a direction along the longitudinal axis 14. If a force Fl is applied to the yielding portion 12 from an upper end 20 in a direction parallel to the axis 14, toward a lower end 22 of the yielding portion 12 and, assuming the end 22 is fixed in terms of being able to 00 move in the axial direction 14, then the yielding portion C 12 will yield by concertinaing in the axial direction 14.
(1 The force Fl in the above described scenario is a 00 compressive force applied to the yielding portion 12. The C concertina effect is provided for by the collapsing in the axial direction of the wall 18 with points on the wall 18 having the maximum radius R1 folding outwardly in a transverse direction R so that these points become axially closer together.
However, the application of a force F2 from the lower end 22 of the yielding portion 12, assuming the upper end is fixed from motion in the axial direction, will result in the yielding portion 12 yielding by virtue of an axial extension in length arising from the flattening or straightening of the corrugations or folds in the wall 18.
This will be accompanied in general by an equalisation of the radii R1 and R2 so that the radius R1 becomes smaller and the radius R2 becomes larger. In this scenario, the force F2 is in effect a tensile force applied to the yielding portion 12 in a direction parallel to the longitudinal axis 14.
In the embodiment depicted in Figures 1 and 2, the bolt further comprises an elongated member 24 that extends through the sleeve 16 and beyond the ends 20 and 22. The elongated member may take any suitable form that is able to bear and transfer a load to the yielding portion 12.
For example, the elongated member 14 may be in the form of a steel rod, a length of rebar, or a multi-strand metal cable.
N \Perlh\Cases\Patent 75000-7599P75903.A1\Specis\P75903.AU.1 Speucficton 2008-7-3 doc 3/07108 00 As explained in greater detail below, depending on the location of coupling between the elongated member 24 and the yielding portion 12, a tensile force applied to the elongated member 24 can be transferred as either a tensile force or a compressive force to the yielding portion 12.
00 Specifically, Figure 2 illustrates the bolt 10 when in use C to support a rock face 26 of a body of rock 28. In order (1 to support the rock face 26, a hole 30 is drilled through 00 the rock face 26 into the body of rock 28. The hole C has a collar 32 adjacent the rock face 26 and a toe 34 at an opposite end inside of the body of rock 28. When in use, the bolt 10 is loaded in the hole 28 with the end of the sleeve 16 facing the toe 34 and the end 22 facing the collar 32. The member 24 is of a length so that a portion 38 extends beyond the rock face 26 when the bolt is in the hole 30. A settable compound such as grout (although other substances such as a settable resin can be used) is injected into the hole 30 and allowed to set.
A clamp 36 is applied to the portion 38 and against the rock face 26.
In the event that a fracture 40 occurs in the body of rock 28 which extends across the hole 30 but to a depth short of the yielding portion 12 and back to the face 26, a tensile force will be applied to the elongated member 24 acting to pull the elongated member 24 through the yielding portion 12 in a direction toward the face 26. If the elongated member 24 is coupled to the yielding portion 12 at or near the end 22, then the tensile force on the elongated member 24 will be transferred as a tensile force to the yielding portion 12. However, if the elongated member 24 is attached to the yielding portion 12 at or near the end 20, then the tensile force on the elongated member 24 will be transferred as a compressive force to the yielding portion 12 assuming of course that the end 22 is substantially fixed.
N:\Perth\Cases\Patent\75DOO-75999\P75903AU. I\Spocis\P759O3AU. 1 Specificalion 20087-3,doc 3107/08 8 Any appropriate coupling or attachment technique device or apparatus can be used for connecting the elongated member 24 to the yielding portion 12. This includes for example s swaging the required end 20 or 22 of the yielding portion 12 to the elongated member 24 or by bonding techniques 0 such as welding, or the use of glues and epoxies; or by mechanical fasteners such as clamps, wedges and collars, (1 or engaging screw threads.
00ooo In order to assist and or regulate the concertinaing (i.e.
axial compression or axial extension) of the yielding portion 12, the bolt 10 may further comprise a sheath or pipe 42 disposed about the yielding portion. The function and purpose of the sheath 42 is to act as a barrier between the yielding portion 12 and the grout 35 in the hole 30 so that the yielding portion 12 can yield with minimal interference from the grout. Thus the force or load transferred onto the yielding portion 12 is utilised essentially wholly by deformation of a material from which the yielding portion 12 is made rather than being at least in part used to displace, compress or otherwise work against the grout that may otherwise reside between corrugations or folds in, or otherwise act to prevent the concertina action of the yielding portion 12.
The sheath 42 may be closed at one or both ends about the yielding portion 12 and may be left either empty or filled with a low density and resilient packing material which further acts to prevent the ingress of grout into the sheath 42.
One or more spacers 44 (see Figure 1) may be provided to maintain the sheath 42 in a substantially coaxial disposition relative to the yielding portion 12. The spacers 44 may also act to retain the sheath 42 on and about the yielding portion 12. In one example, the N:kPerlh\CaseskPatentk75DOO-75999kP75903.AU 1kSpecis\P75903AU.1 Specification 20087-3.doc 3107108 00 O spacers 44 may comprise a resilient ring, or a plurality of resilient fingers or lugs, attached to an inside surface of the sheath 42 and extending in a radially inward direction.
When the elongated member 24 is connected to the end 22 of 00 the yielding portion 12 so that a tensile force applied on the member 24 is transferred as a tensile force to the 00 yielding portion 12, the end 20 should be held in a 00 relatively fixed manner within the hole 30. This can be C achieved in numerous ways. For example one way would be to cut the elongated member 24 at a location inside of the yielding portion 12 to form a separate portion 46 that extends from the end 20 toward the toe 34 and to attach portion 46 to the end 20. Thus the portion 46 set in grout will act as an anchor holding the end 20 allowing the yielding portion 12 to yield by virtue of axial extension. However in an alternate method, separate anchoring pins or lugs may be provided that extend for example radially from the end 20 that are embedded in and thus retained by the grout within the hole 30. In yet a further variation the sleeve 16 can be made of an extended length with a substantial portion of the extended length extending rearwardly of the sheath 42 toward the toe of the hole 34 so as to be held by the grout 35 within the hole 30. Indeed the extended portion of the sleeve 16 can be formed with one or more sets of corrugations or folds that are embedded in the grout 35 to further assist in anchoring the extended length of the sleeve in the grout In the event that the elongated member 24 is coupled to the end 20 so that the yielding portion 12 yields by an axial compression in its length, then the end 22 of the sleeve 16 may be anchored by direct abutment with the set grout within the hole N:\Perth\Cases\Patent\75000-75999\P75903AU. 1\Specis\P75903AU. 1 Specification 2008-7-3.doc 3/07/08 10 Figures 3a and 3b depict alternate states of a different form of yielding portion 12'. The yielding portion 12' comprises a sleeve 16 having a wall 18 that is formed with a plurality of slots or cuts 48. The slots 48 extend in a direction of the longitudinal axis 14 of the yielding portion 12' and form therebetween a series of 00 0 circumferentially spaced links (1 The yielding portion 12' shown in Figure 3a is able to 00 yield in response to an axial compression which results in the folding concertina) of the links 50 as shown in Figure 3b. Thus when a compressive force of sufficient magnitude is applied to the yielding portion 12' as shown in Figure 3a, the links 50 bend or fold outwardly to thereby provide the yielding effect of the yielding portion 12' and leading to a compression in length of the portion 12'. It is also possible for the yielding portion 12' to be used to yield in response to application of a tensile force if the yield portion 12' is initially in the compressed state shown in Figure 3b so that the application of a tensile force results in the straightening of the links 50. It will be further apparent that by providing a yielding portion 12' as shown in Figures 3a and 3b but with the portion 12' in an intermediate state where the sleeve elements 50 are in a partially bent configuration then the yielding portion 12' may accommodate either a tensile or a compressive force.
Figure 4 depicts yet a further and perhaps simplest embodiment of the rock bolt 10 where the yielding portion 12'' is formed as a series of bends along a longitudinal axis 14 of a plastically deformable elongated member 24'.
As the member 24' is typically in the form of a steel bar, this embodiment of the rock bolt is used in tension (i.e.
to yield in response to a tensile load by extension and length arising from the straightening of the bends) rather than to accommodate a compressive load. A sheath (not NAkPerthCases Patentl7500O-75999kP75903.AU 11Spec9sP75903AU 1 Specification 2008-7-3.doc 3/07108 00 11 00 0 shown) similar to sheath 42 shown in Figures 1 and 2 may be provided about the yielding portion 12'' Embodiments of the present invention that would be obvious to a person of ordinary skill in the art are deemed to be within the scope of the present invention the nature of 0 0 which is to be determined from the above description and C the appended claims.
00 o0 N:\Penh\CasesPatent 75DO-75999\P75903AU. 1\SpeCi5\P75903AU. 1 Specification 2008-7-3.doc 3/07/08
Claims (10)
- 3. The yielding rock bolt according to claim 1, wherein the rock bolt is configured so that the yielding portion concertinas in a direction to decrease in length along the longitudinal axis.
- 4. The yielding rock bolt according to any one of claims 1-3, further comprising a sheath disposed about the yielding portion and within which the yielding portion can concertina in response to the applied force.
- 5. The yielding rock bolt according to any one of claims 1-4, wherein the yielding rock bolt comprises a sleeve having opposite first and second ends wherein the yielding portion is a portion of the sleeve.
- 6. The yielding rock bolt according to claim 5, further comprising an elongated member extending through the sleeve and beyond the first and second ends of the sleeve, wherein the elongate member is attached to the sleeve in a manner wherein a force applied to the elongated member is transferred to the sleeve.
- 7. The yielding rock bolt according to claim 6, wherein N\Perth\Cases\Patent\75000-75999\P75903 AU 1\Specis\P75903.AU.1 Specification 2008-7-3 doc 3107108 00 13 00 the elongated member is attached to the sleeve at a location where a tensile force applied to the elongated member is transferred as a tensile force on the yielding portion.
- 8. The yielding rock bolt according to claim 6, wherein 00 0 the elongated member is attached to the sleeve at a location where a tensile force applied to the elongated (1 member is transferred as a compressive force on the 00 yielding portion.
- 9. The yielding rock bolt according to any one of claims 5-8, wherein the yielding portion comprises at least a portion of a length of the sleeve formed with a wall that is configured so that a transverse distance between the longitudinal axis of the sleeve and the wall sequentially increases and decreases in a direction along the longitudinal axis.
- 10. The yielding rock bolt according to any one of claims 5-9, wherein the yielding portion comprises a plurality of slots or cuts formed in a wall of the sleeve about the longitudinal axis forming a series of circumferentially spaced links which are able to fold in response to the application of a compressive force.
- 11. The yielding rock bolt according to any one of claims 1-4, comprising an elongated member wherein the yielding portion comprises a length of the elongated member formed with a plurality of bends that traverse a longitudinal axis of the elongated member.
- 12. A yielding rock bolt substantially as herein described with reference to and as illustrated in any one or more of the accompanying drawings. N.%Perth\Cses\Patent75D-75999\P75903A .1\Specis\P75903A. 1 Specification 208-7-3.doc 3/07/08
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AU2008202980A AU2008202980A1 (en) | 2007-07-04 | 2008-07-04 | Yielding rock bolt |
| AU2008237534A AU2008237534A1 (en) | 2007-07-04 | 2008-10-28 | Yielding rock bolt |
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AU2007903609 | 2007-07-04 | ||
| AU2007903609A AU2007903609A0 (en) | 2007-07-04 | Yielding rock bolt | |
| AU2008202980A AU2008202980A1 (en) | 2007-07-04 | 2008-07-04 | Yielding rock bolt |
Related Child Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| AU2008237534A Division AU2008237534A1 (en) | 2007-07-04 | 2008-10-28 | Yielding rock bolt |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| AU2008202980A1 true AU2008202980A1 (en) | 2009-01-22 |
Family
ID=40293715
Family Applications (2)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| AU2008202980A Abandoned AU2008202980A1 (en) | 2007-07-04 | 2008-07-04 | Yielding rock bolt |
| AU2008237534A Abandoned AU2008237534A1 (en) | 2007-07-04 | 2008-10-28 | Yielding rock bolt |
Family Applications After (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| AU2008237534A Abandoned AU2008237534A1 (en) | 2007-07-04 | 2008-10-28 | Yielding rock bolt |
Country Status (1)
| Country | Link |
|---|---|
| AU (2) | AU2008202980A1 (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103244162A (en) * | 2013-05-27 | 2013-08-14 | 湖南科技大学 | Compressible base plate device and anchor cable anchorage method by device |
| WO2018127294A1 (en) * | 2017-01-09 | 2018-07-12 | Minova International Limited | Composite yieldable rock anchor with improved deformation range |
| CN111022096A (en) * | 2019-12-10 | 2020-04-17 | 华北水利水电大学 | Multistage stress and displacement control extensible anchor rod |
-
2008
- 2008-07-04 AU AU2008202980A patent/AU2008202980A1/en not_active Abandoned
- 2008-10-28 AU AU2008237534A patent/AU2008237534A1/en not_active Abandoned
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103244162A (en) * | 2013-05-27 | 2013-08-14 | 湖南科技大学 | Compressible base plate device and anchor cable anchorage method by device |
| WO2018127294A1 (en) * | 2017-01-09 | 2018-07-12 | Minova International Limited | Composite yieldable rock anchor with improved deformation range |
| US10697297B2 (en) | 2017-01-09 | 2020-06-30 | Minova International Limited | Composite yieldable rock anchor with improved deformation range |
| CN111022096A (en) * | 2019-12-10 | 2020-04-17 | 华北水利水电大学 | Multistage stress and displacement control extensible anchor rod |
Also Published As
| Publication number | Publication date |
|---|---|
| AU2008237534A1 (en) | 2009-01-22 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MK5 | Application lapsed section 142(2)(e) - patent request and compl. specification not accepted |