US3336758A - Rock bolt assembly and procedure for two-stage grouting operations - Google Patents

Rock bolt assembly and procedure for two-stage grouting operations Download PDF

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Publication number
US3336758A
US3336758A US424656A US42465665A US3336758A US 3336758 A US3336758 A US 3336758A US 424656 A US424656 A US 424656A US 42465665 A US42465665 A US 42465665A US 3336758 A US3336758 A US 3336758A
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United States
Prior art keywords
grout
coupling
hole
rod
rock
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Expired - Lifetime
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US424656A
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English (en)
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Chester I Williams
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Individual
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Individual
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Priority to US424656A priority Critical patent/US3336758A/en
Priority to DEW39981A priority patent/DE1226516B/de
Priority to DEW35815U priority patent/DE1946026U/de
Priority to GB160/66A priority patent/GB1085192A/en
Application granted granted Critical
Publication of US3336758A publication Critical patent/US3336758A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • E—FIXED CONSTRUCTIONS
    • E21—EARTH OR ROCK DRILLING; MINING
    • E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
    • E21D20/00—Setting anchoring-bolts
    • E21D20/02—Setting anchoring-bolts with provisions for grouting
    • E21D20/021—Grouting with inorganic components, e.g. cement

Definitions

  • ABSTRACT OF THE DISCLOSURE A method of grouting a rock bolt in position, in which a preliminary charge of grout traverses the entire bolt rod, and is permitted to set, a second charge being delivered via an opening in a coupling interconnecting inner'and outer bolt rod sections.
  • This invention relates to the construction and use of rock bolts.
  • the installation of these bolts in dense rock formations will normally involve installing the bolt in the drilled hole in the rock, followed by securely setting an anchor device mounted at the inner end of the bolt.
  • the bolt rod is then-pre-stressed by application of heavy torsion to a'nut against a surface bearing plate so that the rod is placed under a degree of tension approximating its working load.
  • the rod is then preferably grouted in this condition by pumping a quantity of cementitious liquid into the space within the hole surrounding the rock bolt.
  • this material When this material has hardened, it increases the bond between the bolt and the rock formation for the transfer of stresses, and also'provides a protective shield around the bolt assembly.
  • the pre-stressing operation is very important, as the function of the bolt is then applied to the rock without the necessity of displacement of the rock before the bolt becomes useful.
  • This charge of grout is permitted to harden, and the resulting engagement of the rock bolt assembly is sutficiently improved to permit the pre-stressing operation to be performed.
  • a second charge of grout may be injected after the pre-stressing operation, or the pre-stress may be performed while the secondary charge of grout is still plastic.
  • a sufficient elongation in the bolt rod results from-the pre-stressing operation so that it should not be done after the grout has hardened. To do so will result in breaking the bond between the rod and the grout, and disturbing the sealing elfect of the grout as well.
  • FIGURE 1 presents a sectional elevation showing a rock bolt assembly installed in a hole in a rock formation, prior to the injection of grout.
  • FIGURE 2 illustrates the condition of the inner section of the rock bolt after the initial charge of grout has been injected, and the outer section of the rock bolt (including the coupling) has been removed.
  • FIGURE 3 illustrates the re-coupling of the sections of the rock bolt into the condition shown in FIGURE 1, but with the lateral passage open to receive the second charge of grout, and showing the second charge of grout in position.
  • FIGURE 4 is a section on the plane 4-4 of FIGURE 1, on an enlarged scale.
  • FIGURE 5 is a section on the plane 5-5 of FIG- URE 3.
  • FIGURE 6 is a sectional elevation of a modified form of the invention, in condition corresponding to the injection of the initial charge of grout.
  • FIGURE 7 is a view of the modification shown in FIGURE 6, with the outer rod section back-rotated to expose one of the lateral discharge ports of the coupling.
  • FIGURE 8 is a further modification of the invention in condition preparatory to receiving the first charge of grout.
  • FIGURE 9 is a further modification of the invention, in the initial condition.
  • FIGURE 10 is a section on the plane 1010 of FIG- URE 9.
  • the rock bolt assembly generally indicated at 10 in FIGURES 1-3 is shown installed in the hole 11 in the rock formation 12.
  • the rock bolt assembly includes the outer rod section 13, the inner rod section ⁇ 14, the coupling 15, and an anchor device generally indicated at 16. Both the inner and outer sections of 13 and 14 are tubular, as is the coupling 15.
  • the stresses transferred by the fully installed rock bolt assembly are taken primarily by the bearing plate 17 resting against the surface 18 of the rock formation, with this loading being transferred by the nut 19 and the beveled washer 20.
  • FIGURES 4 and 5 The structural details of the coupling 15 are shown in FIGURES 4 and 5.
  • the unit is tubular in configuration, and preferably threaded throughout its length. The ends are countersunk as shown at 21 and 22 to facilitate the engagement with the ends of the rod sections 13 and 14.
  • a screw plug 23 is engageable with the lateral hole 24 to provide a passage for the flow of grout during-the secondary grouting operation.
  • the removable plug 23 serves the function of a valve and is removed during the time in which the outer rod section 13 (together with the coupling 15) are withdrawn from the bore in the rock formation, as indicated in FIGURE 2.
  • a set screw is located where it will normally engage the end 13 of the outer rod section to assure that the coupling 15 remains rotatably fixed with respect to the outer rod section, rather than remaining on the inner rod section 14.
  • the controllable lateral discharge port provided by the opening 24 and the plug valve 23 makes it possible to deliver an initial charge of grout shown at 26 in FIG- URE 2. After this has set, the outer section of the rod, together with the coupling, may be withdrawn so that the plug 23 may be removed. When the unit is re-connected as shown in FIGURE 3, the secondary charge of grout 27 can be delivered through the opening 24 to occupy the space within the hole 11 around the outer rod section 13.
  • the modified form of the invention shown in FIGURE 6 includes the outer and inner rod sections 28 and 29, respectively, joined by the coupling 30.
  • the threaded length of the ends of the rod sections engaging the coupling is approximately half of the length of the coupling so that the coupling will be properly centered upon the threaded ends, with the same engagement of threads on both rod sections.
  • the coupling is provided with a pair of ports 31 and 32, approximately equally spaced from the adjoining ends of the rod sections 28 and 29.
  • the rod sections 28 and 29 are tubular, and the condition of the device shown in FIGURE 6 corresponds to FIG- URE 1, in the sense that the unit is ready for the delivery of the initial charge of grout.
  • the outer rod section may be back-rotated, with the result that either the opening 31 or the opening 32 (or a portion of both of these) will be exposed.
  • the ends of the rod sections 28 and 29 thus perform the function of valves in place of the removeable plug 23, without the necessity of removing the outer rod section 28 and the coupling 30 from the hole for adjustment.
  • the outer rod section may be cleared of grout either with water under pressure, or by compressed air. Whichever is the case, the outflow will take place through the opening 31 or 32 (or partially through both), and the initial charge of grout may be permitted to set.
  • the rock bolt assembly may then be prestressed, followed by a secondary injection of grout which will then fiow out through the holes 31 and/ or 32.
  • the length of the coupling 30 should be established such that there will be adequate thread engagement between the end 28 or 29 and the coupling for full transfer of stress when in the backed-off condition of the assembly.
  • the rubber ring 33 is added to the inner rod section 29 to facilitate grouting when the hole in the rock formation extends upwardly from the point at which the rock bolt assembly is inserted.
  • the ring 33 will act as a dam bearing lightly against the wall of the hole in the rock, tending to confine the initial charge of grout so that it will properly surround the inner section 29 and the anchor device.
  • FIGURE 8 a modified form of the invention is illustrated in which the outer rod section 34 is connected to the inner rod section 35 by the coupling 36.
  • Spaced side holes 37 and 38 serve the same function as the holes 31 and 32 of FIGURES 6 and 7.
  • a pair of balls shown at 39 and 40 are provided as abutments transferring the axial forces between the ends of the rod sections 34 and 35 to minimize the jamming action resulting from the heavy torque applied to set the anchor device.
  • the outer rod section may be back-rotated with a minimum danger of unscrewing the inner rod section 35 from the anchor device.
  • a pair of balls 39 and 40 are used in preference to a single ball to minimize the danger that a single ball might assume a position on the axis of the rod sections 34 and 35 to function as a ball valve, and thus block the fiow of grout to the inner rod section.
  • these holes should be of slightly greater diameter than that of the balls 39 and 40.
  • a further modification of the invention illustrates the provision of a single ball 41 between the ends 42 and 43 of the outer and inner rod sections, respectively.
  • the coupling 44 is similar to the couplings 30 and 36, and is provided with the pair of holes 45 and 46.
  • a strip of leaf-spring material 48 is inserted in a position to maintain a biasing effect holding the ball 41 in an eccentric position.
  • Both the balls 41 and 3940 should be of hardened steel in order to sustain a tremendous end pressure resulting from the setting of the anchor device.
  • a method of grouting a rock bolt in two stages comprising:
  • assembling a tubular bolt rod including at least two sections connected by a tubular coupling provided with a hole at an intermediate point along its length, the inner of said sections having an anchor device secured thereto;
  • a rock bolt assembly for two-stage grouting comprising:
  • tubular bolt rod having at least inner and outer separate sections
  • a tubular coupling having threaded engagement with said rod sections, said coupling having at least one hole in the wall thereof at an intermediate point along the length of said coupling;
  • valve means for closing and opening said coupling hole.
  • valve means is a screw plug.
  • valve means is the end portion of at least one of said rod sections.

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  • Engineering & Computer Science (AREA)
  • Mining & Mineral Resources (AREA)
  • Chemical & Material Sciences (AREA)
  • Inorganic Chemistry (AREA)
  • Structural Engineering (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Geology (AREA)
  • Piles And Underground Anchors (AREA)
US424656A 1965-01-11 1965-01-11 Rock bolt assembly and procedure for two-stage grouting operations Expired - Lifetime US3336758A (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
US424656A US3336758A (en) 1965-01-11 1965-01-11 Rock bolt assembly and procedure for two-stage grouting operations
DEW39981A DE1226516B (de) 1965-01-11 1965-09-25 Verfahren zum zweistufigen Einbetonieren von Gebirgsanker und ein Anker hierfuer
DEW35815U DE1946026U (de) 1965-01-11 1965-09-25 Gebirgsanker.
GB160/66A GB1085192A (en) 1965-01-11 1966-01-03 Rock-bolt grouting operations

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US424656A US3336758A (en) 1965-01-11 1965-01-11 Rock bolt assembly and procedure for two-stage grouting operations

Publications (1)

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US3336758A true US3336758A (en) 1967-08-22

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US (1) US3336758A (de)
DE (2) DE1226516B (de)
GB (1) GB1085192A (de)

Cited By (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3412561A (en) * 1965-12-16 1968-11-26 Reid Giorgina Reed-trench terracing
US3837258A (en) * 1970-02-03 1974-09-24 C Williams Rock bolts
US3908386A (en) * 1970-08-03 1975-09-30 Chester I Williams Rock bolt for remote installation
US4051683A (en) * 1976-06-28 1977-10-04 Jennmar Corporation Method and apparatus for supporting a mine roof
US5374140A (en) * 1990-07-03 1994-12-20 Standish; Peter N. Drillable ground support bolt
US5888025A (en) * 1994-11-25 1999-03-30 Mai Pump Austria Gmbh Coupling for tie rods
US5906466A (en) * 1995-04-05 1999-05-25 Eandi; Roger E. Plug washer
US6499268B2 (en) * 2000-04-28 2002-12-31 Peter James Reinforcing structures
US9949563B2 (en) 2012-06-16 2018-04-24 Stact Wine Displays Inc. Bottle rack and kit for bottle-supporting assembly
US10004330B1 (en) * 2016-12-23 2018-06-26 Stact Wine Displays Inc. Bottle rack
USD821831S1 (en) 2015-03-24 2018-07-03 Stact Wine Displays Inc. Bottle rack
US10028625B2 (en) * 2016-12-08 2018-07-24 Marion J Tarlton Over a sink retractable and extendable towel hanging apparatus
USD834900S1 (en) 2017-01-04 2018-12-04 Stact Wine Displays Inc. Bottle rack
USD848802S1 (en) 2017-01-04 2019-05-21 Stact Wine Displays Inc. Bottle rack
USD878828S1 (en) 2017-11-13 2020-03-24 Stact Wine Displays Inc. Bottle rack
USD923987S1 (en) 2017-11-13 2021-07-06 Stact Wine Displays Inc. Bottle racks
US20220049448A1 (en) * 2018-09-26 2022-02-17 Bauer Spezialtiefbau Gmbh Method for producing an injection anchor in the ground and automatic post-grouting machine for the same

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2903137C3 (de) * 1979-01-27 1982-02-18 Bergwerksverband Gmbh, 4300 Essen Rohrförmiger verlorener Bohrlochverschluß
GB2244533B (en) * 1990-04-30 1994-09-28 David Patrick Payne Fixing anchors in cavities

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2442113A (en) * 1945-05-25 1948-05-25 Beijl Zako Sytse Tunnelling and like subterranean operations
GB790483A (en) * 1954-01-02 1958-02-12 Wilhelm Weghuber Improvements in or relating to methods for connecting layers of rock by means of rock anchors in mining operations and means for carrying said methods into effect
US2829502A (en) * 1953-12-17 1958-04-08 Joseph B Dempsey Mine roof bolt installation
FR1268624A (fr) * 1960-06-24 1961-08-04 Forges Et Boulonneries Hermant Dispositif d'ancrage perfectionné

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2442113A (en) * 1945-05-25 1948-05-25 Beijl Zako Sytse Tunnelling and like subterranean operations
US2829502A (en) * 1953-12-17 1958-04-08 Joseph B Dempsey Mine roof bolt installation
GB790483A (en) * 1954-01-02 1958-02-12 Wilhelm Weghuber Improvements in or relating to methods for connecting layers of rock by means of rock anchors in mining operations and means for carrying said methods into effect
FR1268624A (fr) * 1960-06-24 1961-08-04 Forges Et Boulonneries Hermant Dispositif d'ancrage perfectionné

Cited By (24)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3412561A (en) * 1965-12-16 1968-11-26 Reid Giorgina Reed-trench terracing
US3837258A (en) * 1970-02-03 1974-09-24 C Williams Rock bolts
US3908386A (en) * 1970-08-03 1975-09-30 Chester I Williams Rock bolt for remote installation
US4051683A (en) * 1976-06-28 1977-10-04 Jennmar Corporation Method and apparatus for supporting a mine roof
US5374140A (en) * 1990-07-03 1994-12-20 Standish; Peter N. Drillable ground support bolt
US5888025A (en) * 1994-11-25 1999-03-30 Mai Pump Austria Gmbh Coupling for tie rods
US5906466A (en) * 1995-04-05 1999-05-25 Eandi; Roger E. Plug washer
US6499268B2 (en) * 2000-04-28 2002-12-31 Peter James Reinforcing structures
US9949563B2 (en) 2012-06-16 2018-04-24 Stact Wine Displays Inc. Bottle rack and kit for bottle-supporting assembly
US10441075B2 (en) 2012-06-16 2019-10-15 Stact Wine Displays Inc. Bottle rack and kit for bottle-supporting assembly
USD821831S1 (en) 2015-03-24 2018-07-03 Stact Wine Displays Inc. Bottle rack
USD891202S1 (en) 2015-03-24 2020-07-28 Stact Wine Displays Inc. Bottle rack
US10028625B2 (en) * 2016-12-08 2018-07-24 Marion J Tarlton Over a sink retractable and extendable towel hanging apparatus
US10004330B1 (en) * 2016-12-23 2018-06-26 Stact Wine Displays Inc. Bottle rack
US11382424B2 (en) 2016-12-23 2022-07-12 Stact Wine Displays Inc. Bottle rack
US10835037B2 (en) 2016-12-23 2020-11-17 Stact Wine Displays Inc. Bottle rack
USD834900S1 (en) 2017-01-04 2018-12-04 Stact Wine Displays Inc. Bottle rack
USD848802S1 (en) 2017-01-04 2019-05-21 Stact Wine Displays Inc. Bottle rack
USD878828S1 (en) 2017-11-13 2020-03-24 Stact Wine Displays Inc. Bottle rack
USD923987S1 (en) 2017-11-13 2021-07-06 Stact Wine Displays Inc. Bottle racks
USD994404S1 (en) 2017-11-13 2023-08-08 Stact Wine Displays Inc. Bottle racks
USD1027580S1 (en) 2017-11-13 2024-05-21 Stact Wine Displays Inc. Bottle racks
US20220049448A1 (en) * 2018-09-26 2022-02-17 Bauer Spezialtiefbau Gmbh Method for producing an injection anchor in the ground and automatic post-grouting machine for the same
US11993910B2 (en) * 2018-09-26 2024-05-28 Bauer Spezialtiefbau Gmbh Method for producing an injection anchor in the ground and automatic post-grouting machine for the same

Also Published As

Publication number Publication date
GB1085192A (en) 1967-09-27
DE1226516B (de) 1966-10-13
DE1946026U (de) 1966-09-15

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