WO2001046558A1 - An anchor device for use in mining - Google Patents
An anchor device for use in mining Download PDFInfo
- Publication number
- WO2001046558A1 WO2001046558A1 PCT/AU2000/001583 AU0001583W WO0146558A1 WO 2001046558 A1 WO2001046558 A1 WO 2001046558A1 AU 0001583 W AU0001583 W AU 0001583W WO 0146558 A1 WO0146558 A1 WO 0146558A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- bore
- arms
- anchor device
- section
- contact portions
- Prior art date
Links
- 238000005065 mining Methods 0.000 title description 3
- 238000003780 insertion Methods 0.000 claims abstract description 6
- 230000037431 insertion Effects 0.000 claims abstract description 6
- 238000005452 bending Methods 0.000 description 4
- 238000009434 installation Methods 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 230000008901 benefit Effects 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 230000008859 change Effects 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000006870 function Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000008447 perception Effects 0.000 description 1
- 238000005482 strain hardening 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
- E21D21/004—Bolts held in the borehole by friction all along their length, without additional fixing means
Definitions
- This invention relates to an anchor device for engaging in a bore and, more particularly, but not exclusively, to an anchor device for use in mining applications.
- a friction bolt used in the mining industry is know as a friction bolt. It comprises a tapered substantially tubular body, with a C-shaped transverse cross-section.
- the C-shaped cross-section enables the body to be radially compressed to fit within a bore such that when inserted into the bore, elastic compression of the body causes a radially outward force to be exerted upon the sides of the bore to thereby anchor the bolt in place.
- the bolt may be fitted with a load plate or the like which is fixed in place by a ring secured to a free end of the bolt.
- the present invention seeks to provide an anchor device of alternative construction.
- an anchor device for engagement with a wall of a bore, the device having a profile including two interconnected arms defining a gap between free ends thereof to accommodate relative movement of the free ends resulting from deflection of the arms during insertion in the bore, wherein the arms are coupled via an intermediate section which includes an inset portion, at which the profile is in use spaced from the bore wall, so as to define contact portions at either side thereof for contact with the wall and wherein the inset portion is located substantially diametrically opposite the gap.
- the contact portions are respectively substantially diametrically opposite the free ends of the arms.
- the inset portion is defined by a concave section and a relative angle between an imaginary line drawn along any two parts of the section is less than 90°.
- an anchor device for frictional engagement in a bore, including two arms extending from an intermediate section, the section being provided with lateral contact portions for engaging the bore wall and the arms being arranged to deflect about spaced apart loci.
- the device is provided with an inset portion intermediate the contact portions, about which the arms hinge.
- the contact portions substantially correspond to respective locations at which the arms couple to the intermediate section.
- the spaced apart loci are substantially congruent with a respective one of the contact portions.
- an anchor device for frictional engagement in a bore including an elongate body having a transverse cross-section defined by two arms coupled to an intermediate section, with free ends of the arms being separated by a gap which is sufficient to allow the device to be compressed during insertion of the device into the bore, wherein the section includes an inset portion opposite the gap with contact portions provided at either side thereof for engagement with a wall of the bore.
- the recessed region is defined by a concave section of the intermediate section.
- At least one end of the device is tapered.
- an anchor device for frictional engagement in a bore, including two arms extending from an intermediate section, the intermediate section having a plurality of contact portions for engaging a wall of the bore.
- Figure 1 is an enlarged cross-sectional view of a prior art friction bolt in a compressed configuration within a bore
- Figure 2 is an enlarged cross-sectional view of an anchor device according to the present invention, the device being in a compressed configuration within a bore;
- Figure 3 is a graph illustrating pressure profiles for the device of Figure 2 and the bolt of Figure 1;
- Figure 4 is a side view of the device shown in Figure 2.
- a prior art of friction bolt 1 is shown as comprising a body 2 with a 'C'-shaped section terminating in free ends 3,4 which are arranged to deflect about a single locus 5, which corresponds to a geometric centre 6 of the body.
- the bolt is thereby arranged to frictionally engage a wall 7 of a bore 8 at only three points 9, 10, 11, which reduces the load bearing capacity of the bolt 1.
- the distance between the free ends 3, 4 and the locus 5 is usually maximised which maximises bending moments applied to the free ends 3,4 of the body 2. That in turn can limit the contact force which may be applied between the bolt 1 and the bore, prior to failure of the bolt due to excessive bending moments being applied.
- an anchor device 20 of the present invention is shown as including a body 21 with a transverse cross-section defined by two arms 22,23 coupled to an intermediate section 24.
- the device 20 has an inset portion 25 defined by a concave section 26 of the intermediate section 24.
- Laterally spaced contact portions 27,28 are provided at either side of the portion 25, for engagement with a wall 29 of bore 30.
- the portion 25 is substantially diametrically opposite a gap 52 provided between the arms 22,23 and each contact portion 27,28 is arranged generally opposite a respective free end of the arms.
- the contact portions 27,28 substantially correspond to respective locations 31,32 where the arms 22,23 join with the section 24.
- the locations 31,32 also form or are substantially congruent with loci 33, about which the arms 22,23 deflect.
- the device 20 thereby provides four contact points for engagement with the wall 29; two points adjacent free ends 34,35 of the arms 22,23 and two further points associated with the portions 27,28.
- the increased number of contact points, as compared to the bolt 1 of Figure 1, allows for greater load bearing capacity, as reflected in experimental results, shown in Figure 3.
- That Figure shows a plot of contact force versus radial angle, where 180° represents the locus 5 of the bolt 1 and the corresponding position of the device 20.
- the curves 40, 41 and 42 show sustainable contact forces about respective points 9, 10 and 11 of the bolt 1, while the curves 43, 44, 45 and 46 show sustainable contact forces about the free ends 34,35 and the contact portions 27,28, respectively.
- the device 20 also reduces the length of the arms 22,23, as a result of introduction of the intermediate section 24, as compared to the bolt 1 and that has the affect of reducing the bending moment for equivalent force application, which in turn increases the comparative load bearing limit of the device 20, prior to failure.
- the inset portion 25 although shown as being somewhat concave, is still reasonably flat, in order that the portion 25 does not itself function as a hinge point or section of weakness in the device. To ensure that is the case, the portion 25 is formed such that a relative angle " ⁇ ", between an imaginary line 61,62, drawn along any two parts of the section 25 is less, and preferably substantially less, than 90°.
- the above advantages may be utilised to reduce material required to produce a device having similar load bearing capabilities as the bolt 1 or alternatively a device may be provided using a similar amount of material with enhanced load bearing characteristics.
- the device 20 can be seen as being formed as an elongate friction bolt 50 with a tapered end 51 and an axially extending gap 52 defined between the free ends 34,35 of the arms 22,23.
- the device 20 may, however, instead comprise only a portion of the bolt, such as the tapered end 51 or, alternatively, be in the form of an attachment device which is simply fitted to an existing bolt or formed at an end thereof, in order to provide improved load bearing characteristics.
- the comparative load bearing advantage of the device of the invention may be seen as resulting from the shape of the bolt cross-section, and the resulting location and orientation of the four contact regions between the bolt and the bore wall, with the bolt cross-section functioning as an array of three relatively short, stiff beam- columns.
- the free ends 34,35 of the cross-section close together pivoting at 33 with the arms 22,23 maintaining the original pre-installation radii.
- the arms 22,23 behave as short curved beams whereas in the prior art bolt configuration the curved sections are longer and less stiff.
- the curved section 25 is also quite rigid, which is the result of being of a relatively short length and having three small radii resulting from cold working of the metal during a roll forming process.
- the roll forming process takes the metal into the plastic or permanent deformation zone.
- the curvature of each arm of the prior art configuration is around 175 degrees whereas the profile of the device 20 is around 155 degrees. This reduced curvature and resulting shorter arm length means that for the same deflection during installation (hole diameter does not change) a greater contact force or pressure is achieved at the ends 34,35. Bending moments at the contact portions 27,28 are greater than what is achieved at the single point 11 of the prior art configuration. This is supported by Figure 3 which shows higher local stress areas at portions 27,28.
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)
- Dowels (AREA)
Abstract
Description
Claims
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AU23309/01A AU779367B2 (en) | 1999-12-21 | 2000-12-21 | An anchor device for use in mining |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AUPQ4776A AUPQ477699A0 (en) | 1999-12-21 | 1999-12-21 | An anchor device for use in mining |
AUPQ4776 | 1999-12-21 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2001046558A1 true WO2001046558A1 (en) | 2001-06-28 |
Family
ID=3818915
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/AU2000/001583 WO2001046558A1 (en) | 1999-12-21 | 2000-12-21 | An anchor device for use in mining |
Country Status (2)
Country | Link |
---|---|
AU (1) | AUPQ477699A0 (en) |
WO (1) | WO2001046558A1 (en) |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4472087A (en) * | 1980-03-28 | 1984-09-18 | Elders G W | Roof support pin |
US5192146A (en) * | 1991-08-30 | 1993-03-09 | Simmons-Rand Company | Open seam friction rock stabilizer |
AU6870494A (en) * | 1993-07-03 | 1995-02-09 | Hugotek (Proprietary) Limited | Friction rock stabilizers |
-
1999
- 1999-12-21 AU AUPQ4776A patent/AUPQ477699A0/en not_active Abandoned
-
2000
- 2000-12-21 WO PCT/AU2000/001583 patent/WO2001046558A1/en active IP Right Grant
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4472087A (en) * | 1980-03-28 | 1984-09-18 | Elders G W | Roof support pin |
US5192146A (en) * | 1991-08-30 | 1993-03-09 | Simmons-Rand Company | Open seam friction rock stabilizer |
AU6870494A (en) * | 1993-07-03 | 1995-02-09 | Hugotek (Proprietary) Limited | Friction rock stabilizers |
Also Published As
Publication number | Publication date |
---|---|
AUPQ477699A0 (en) | 2000-02-03 |
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