WO1988002437A1 - Boulons ou ancrages pour renforcer des couches de terre - Google Patents

Boulons ou ancrages pour renforcer des couches de terre Download PDF

Info

Publication number
WO1988002437A1
WO1988002437A1 PCT/GB1987/000686 GB8700686W WO8802437A1 WO 1988002437 A1 WO1988002437 A1 WO 1988002437A1 GB 8700686 W GB8700686 W GB 8700686W WO 8802437 A1 WO8802437 A1 WO 8802437A1
Authority
WO
WIPO (PCT)
Prior art keywords
strata
bolt
tube
slug
inner end
Prior art date
Application number
PCT/GB1987/000686
Other languages
English (en)
Inventor
Allan Richard Hilton
Original Assignee
Hilton Allan R
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Hilton Allan R filed Critical Hilton Allan R
Publication of WO1988002437A1 publication Critical patent/WO1988002437A1/fr

Links

Classifications

    • E—FIXED CONSTRUCTIONS
    • E21—EARTH 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
    • E21D21/0086—Bearing plates
    • E—FIXED CONSTRUCTIONS
    • E21—EARTH 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
    • E—FIXED CONSTRUCTIONS
    • E21—EARTH 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

Definitions

  • the invention relates to earth strata bolts or anchorages used, for example, in the stabilisation and reinforcement of earth strata such for example, as rock in quarrying, and for roof support in underground mines and tunnels for example.
  • earth strata bolts or anchorages used, for example, in the stabilisation and reinforcement of earth strata such for example, as rock in quarrying, and for roof support in underground mines and tunnels for example.
  • Strata bolts according to this invention are primarily for use in competent strata but can be used in friable and unconsolidated stratas or ground.
  • a strata bolt comprises an axially-split tube capable of peripheral expansion, and open at its outer end, and an expander slug for insertion into and passage along the tube to effect said peripheral expansion and effect a positive location between the bolt and the surrounding strata to provide a primary anchorage therebetween.
  • the tube at its inner end is axially split at a plurality of angularly-spaced locations at its inner end and is of reduced inner cross-sectional area at its inner end whereby the primary anchorage due to the action of the expander slug is effected at the inner end of the strata bolt.
  • the tube is fitted internally at its inner end with a tapered insert adapted to be acted upon by the expander slug which is of tapered configuration.
  • the inner end of the tube is formed as a return bend and is peripherally inwardly compressed.
  • the outer end of the tube is outwardly flanged.
  • a resilient indicator plate of dished construction is provided and is adapted to be slid onto the tube for location between the earth or rock strata and the outer end flanging, which tube is adapted to be flattened upon pre-tensioning of the strata bolt on its insertion into a hole in the strata to provide a visual indication of correct anchorage of the stratabolt.
  • Fig. 1 is a longitudinal cross-sectional view of a preferred form of strata bolt with an anchorage slug an d a pressure slig located within the strata bolt;
  • Fig. 2 is a detail view of an alternative outer end locating configuration
  • Fig. 3 is an end view of the inner end of the strata bolt
  • Figs. 4 and 5 are respectively a fragmentary sectional view and a fragmentary perspective view of the outer end of the strata bolt with an associated pre-tension and/or load indicator plate;
  • Fig. 6 is a perspective part-sectional view of an alternative form of strata bolt with associated indicator plate
  • Fig. 7 is a sectional detail view of the inner end of the strata bolt of Fig. 6;
  • Figs. 8 and 8A are perspective views of alternative forms of slug
  • Fig. 9 is a detail view of a modification of the slugs of Figs. 8 and 8A.
  • Fig. 10 illustrates the sequence of fixing a strata bolt in position.
  • the strata bolt 20 comprises a metal, say a steel, tube 21 axially split along its whole length as indicated at 22.
  • the tube 21 may be tack welded at one or more locations along the length of the split 22 or the split 22 may be of interrupted construction (any sequence of split, non-split).
  • the bore 21A of the tube 21 is parallel from the outer end 21B to the inner end 21C.
  • the inner end 21C of the tube 21 has fitted therein a Morse taper insert 23 (No. 2 Morse for example), which is welded inside the tube 21 as indicated at 24.
  • the inner end 21C of the tube 21 and the Morse taper insert 23 are, after welding of the latter in position, axially slit at four equi-angularly spaced locations 25 (see Fig. 3).
  • the outer end 21B of the tube 21 is outwardly flanged as indicated at 27 by turning over the extremity of said outer end 21B as shown.
  • FIG. 2 An alternative outer end construction (Fig. 2) is provided by welding, as indicated at 28, ar ⁇ und the outer end a collar 29 which is externally screw-threaded as indicated at 30. Due to the provision of this collar 29 the tube 21, in this example is wider at its outer end 21B to facilitate entry of expander slugs referred to hereafter.
  • the major length of the tube bore 21A after a short tapered length at the outer end is of parallel configuration.
  • Expander slugs are used with the strata bolt 20 and in Fig. 1 is shown an anchorage slug 31 and a pressure, slug, 32.
  • These slugs 31, 32 are tapers (for example No. 2 Morse) and differ in their cross-sectional area dimension, the pressure slug 32 having a greater cross-sectional area dimension than the anchorage slug 31.
  • a number of pressure slugs 32 of increasing cross-sectional area dimesnion may be provided. It is considered that three sizes of pressure slugs 32 will probably be sufficient, each size larger than the other but this number is not limitative.
  • tapered expander slugs whether anchorage or pressure, may alternatively be constructed in accordance with Figs. 8, 8A and 9.
  • the tapered expander slug 33 of Fig. 8 has circumferentially-spaced fins 34 extending its full length while that of Fig. 8A has circumferentially- spaced fins 35 terminating at a bullet-shaped nose 36.
  • the fins 34 and 35 may be indented or of toothed configuration as shown in Fig. 9.
  • the outer surface of the tube 21 or an area of areas thereof may be roughened, indented or fletched as indicated at 37 to improve anchoring of the strata bolt 20 to the earth strata or rock (see Figs. 6 and 10).
  • An indicator or "tell-tale" plate 39 (Figs. 4, 5 and 10) is provided for use with the strata bolt 20 when necessary. It will more often not be used than used.
  • the indicator plate 39 is a spring disc 40 of generally dished configuration with a central hole 41, and, in use, it is slid onto the tube 21 and is disposed between the outer end flange 27 or 29 and the earth and/or rock strata 42 with a resilient washer 43 located between the flange 27 or 29 and the indicator plate 39.
  • Anchoring of the strata bolt 20 in the earth and/or rock strata 42 will now be described with reference to the sequence illustrations of Fig. 10.
  • the anchoring is described using the indicator plate 39 but, as aforesaid, the use of this indicator plate 39 is optional.
  • the first step is to drill a hole 44 in the strata 42, which hole 44 is slightly over-size relative to the outside diameter of the strata bolt 20.
  • the second step is to insert the strata bolt 20 with the indicator plate 39 and the resilient washer 43 fitted thereon into the hole 44.
  • the third step involves pre-tensioning or loading the strata bolt 20 using a pressure (usually hydraulic) cylinder 45 of tubular configuration applied against the flange 27 or 29, washer 43 and indicator plate 39.
  • the fourth step comprises driving, by means of a plunger rod 46, an anchorage slug 31 up through the pressure cylinder bore and tapered bore 21A of the tube 21 of the strata bolt 20 into the inner end 21C whereof the coacting Morse tapers of the slug 31 and the insert 23 and the slits 25 and holes 26 cause said inner end 21C to expand circumferentially outwardly to create an end anchorage between the strata bolt 20 and the strata 42. In competent strata such, for example, as rock such end anchoring may be sufficient. If not, or if the strata is soft or friable, one or more pressure slugs 32 are driven, in the same way, into the tube 21 of the strata bolt 20. These pressure slugs 32 of the required or desired size or sizes are driven into the tube 21 to an appropriate location.
  • the fifth step comprises releasing the pressure applied by the pressure cylinder 45. If the spring disc indicator plate 39, which would be flattened from its dished shape when the pressure was applied, returns to its dished shape then this indicates that the anchorage between the strata bolt 20 and the strata 43 has not been fully developed. In this circumstance, pressure is once again applied and one or more additional pressure slugs 32 is or are driven into the tube 21. This is done until, upon pressure release, the indicator plate 39 remains flat.
  • the anchorage of a strata bolt 20 fails and the latter falls wholly, or more likely partially out of the hole 44, then the anchorage can be readily re-established by pre-tensioning or loading the strata bolt 20 into the hole 44 and driving in one or more pressure slugs 32 of appropriate size.
  • a strata bolt 20 drops partly out of the hole 44 its anchorage can be re-established (without pushing it back into the hole 44 which might be difficult or not possible) simply by driving in one or more pressure slugs to a convenient location or locations, say, for example, one pressure slug up to the anchorage slug and another to a location just above the bottom of the hole 44.
  • the length of the slits 25 can be increased.
  • the strata bolt may be formed of two lengths of tube welded together, the length which includes the inner end being formed internally, say, by boring to provide the taper equivalent to the taper insert 23.
  • the strata bolt 50 comprises an axially-split tube 51, a pre-tensioning and/or load indicator plate 52, and one or more expander slugs 31, 32, 33.
  • the tube 51 is formed by, for example, cold rolling steel plate, the axial slit being indicated at 53. Indents 37 or holes 38 are preferably formed on the outer surface of the tube 51 to provide keying formations and so improve anchoring.
  • the length of the tube 51 is made to suit customer requirements, for example between six and twelve feet. This applies equally to the embodiment of Fig. 1.
  • the tube 51 is tack welded adjacent each end say, for example, three inches from the inner end as indicated at 54, and one inch from the outer end as indicated at 55.
  • axial slits 56 are formed in the wall of the tube 51 at the inner end for a length which stops short, of the tack welding 54 say for example a length of two and three quarter inches.
  • the tube 51 at its outer end is rolled back to provide an external circumferential flange 57, and, at its inner end, is rolled back for a distance say of one inch to form a return bend and is inwardly compressed to form a bullet head 58 with indents 59.
  • the diameter of the bullet head 58 does not exceed the diameter of the tube 51 as can be seen.
  • the optional indicator plate 52 is a spring steel disc of dished shape as indicated at 60. It has a hole 61 for passage of the tube 51 but not the flange 57 and is cut at a number (only one shown) of locations inwardly from its periphery as indicated at 62 to facilitate flattening thereof.
  • strata bolts which are long established and well-known to those skilled in the art, and which comprise, inter alia, cement grouted bolts, pre-tensioned resin grouted bolts, expansion bolts, cement grouted wedge type bolts and friction bolts
  • strata bolts according to the present invention have the following advantages:-
  • anchor resistance which can be developed to provide (by use of pressure slugs) a partial or full column anchor resistance to take into consideration variable rock or ground strata conditions as encountered.
  • the strata bolt is provided with a pre-tensioning facilitity to ensure application of a predetermined load to the bolt during installation, which facility automatically and clearly shows its anchorage state or condition without recourse to instrumentation.
  • the strata bolt substantially fills the hole drilled in the earth or rock strata and, as a result, it accommodates lateral movement and forces.
  • the strata bolt is quickly and easily installed by hand or machine, and is easy to handle and transport.
  • the strata bolt can be made of, or treated with, corrosion resistant material.

Abstract

Un boulon (20) pour stabiliser ou renforcer des couches de terre et/ou de roches comprend un tube fendu axialement (21) capable d'expansion périphérique et ouvert à son extrémité externe (21B) et un tronc de cône expanseur (31) destiné à être inséré dans un tube sur toute sa longueur, permettant ainsi son expansion périphérique et un positionnement positif entre le boulon et la couche environnante, de façon à former un ancrage principal entre eux. Le tube (20) est fendu axialement en plusieurs endroits angulairement espacés (25) au niveau de son extrémité interne (21C) où sa surface interne de section transversale est réduite, l'ancrage principal dû à l'action du tronc de cône expanseur étant effectué au niveau de l'extrémité interne du boulon de renforcement. Sont de préférence prévus un seul tronc de cône d'ancrage et plusieurs troncs de cône de pression (22), dont la surface de section transversale est de diverses grandeurs mais toujours plus grande que la surface de section transversale du tronc de cône d'ancrage.
PCT/GB1987/000686 1986-10-02 1987-09-30 Boulons ou ancrages pour renforcer des couches de terre WO1988002437A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB8623686 1986-10-02
GB868623686A GB8623686D0 (en) 1986-10-02 1986-10-02 Strata bolts

Publications (1)

Publication Number Publication Date
WO1988002437A1 true WO1988002437A1 (fr) 1988-04-07

Family

ID=10605157

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB1987/000686 WO1988002437A1 (fr) 1986-10-02 1987-09-30 Boulons ou ancrages pour renforcer des couches de terre

Country Status (4)

Country Link
AU (1) AU8032987A (fr)
GB (1) GB8623686D0 (fr)
WO (1) WO1988002437A1 (fr)
ZA (1) ZA877422B (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0353050A1 (fr) * 1988-07-26 1990-01-31 Delkor Technik (Proprietary) Limited Boulon d'ancrage de roche
WO1999050531A1 (fr) * 1998-03-30 1999-10-07 Craig John Smith Stabilisateur de roches a friction
US10370968B2 (en) * 2015-11-30 2019-08-06 Sandvik Intellectual Property Ab Friction bolt

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1110591B (de) * 1960-04-30 1961-07-13 Hans Ziller Raubbarer Gesteinsanker
FR2340419A1 (fr) * 1975-12-12 1977-09-02 Tornado Gmbh Dispositif d'ancrage
US4098087A (en) * 1976-12-02 1978-07-04 Battelle Development Corporation Anchoring bolt and method
US4183699A (en) * 1978-05-18 1980-01-15 Donan David C Jr Washer/gasket for mine roof bolt assembly
US4312604A (en) * 1980-07-17 1982-01-26 Ingersoll-Rand Co. Friction rock stabilizer set, and a method of fixing a friction rock stabilizer in an earth structure bore
GB2153475A (en) * 1984-01-23 1985-08-21 Edward Victor Byers Anchoring of rock bolts

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1110591B (de) * 1960-04-30 1961-07-13 Hans Ziller Raubbarer Gesteinsanker
FR2340419A1 (fr) * 1975-12-12 1977-09-02 Tornado Gmbh Dispositif d'ancrage
US4098087A (en) * 1976-12-02 1978-07-04 Battelle Development Corporation Anchoring bolt and method
US4183699A (en) * 1978-05-18 1980-01-15 Donan David C Jr Washer/gasket for mine roof bolt assembly
US4312604A (en) * 1980-07-17 1982-01-26 Ingersoll-Rand Co. Friction rock stabilizer set, and a method of fixing a friction rock stabilizer in an earth structure bore
GB2153475A (en) * 1984-01-23 1985-08-21 Edward Victor Byers Anchoring of rock bolts

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0353050A1 (fr) * 1988-07-26 1990-01-31 Delkor Technik (Proprietary) Limited Boulon d'ancrage de roche
US5112160A (en) * 1988-07-26 1992-05-12 Delkor Technik Limited Rock anchor
WO1999050531A1 (fr) * 1998-03-30 1999-10-07 Craig John Smith Stabilisateur de roches a friction
US10370968B2 (en) * 2015-11-30 2019-08-06 Sandvik Intellectual Property Ab Friction bolt
US20190316467A1 (en) * 2015-11-30 2019-10-17 Sandvik Intellectual Property Ab Friction bolt
US10837280B2 (en) * 2015-11-30 2020-11-17 Sandvik Intellectual Property Ab Friction bolt

Also Published As

Publication number Publication date
AU8032987A (en) 1988-04-21
ZA877422B (en) 1988-06-29
GB8623686D0 (en) 1986-11-05

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