Patent US3942329A successfully refreshed from Google Patents.
US3942329A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Flexible rock bolt
Assignee: United States Department of the Interior
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Filing: 1975-02-11
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Granted: 1976-03-09
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Expires: 1995-02-11
Abstract
Abstract A flexible rock bolt for use in anchoring mine structures to ground formations and in supporting such structures which consists of a rock bolt helically coiled into a spring shape having relatively large pitch and a spring index of at least two which allows the rock bolt to elongate upon application of tension and torsion loading and allows the rock bolt to contract under compression.
Inventors
- 👤 Clarence O. Babcock
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 03:47
CPC Classifications
F; F16; F16B; F16B13/00; E; E21; E21D; E21D21/00; E21D21/0006; E21D21/0026; F16B31/00; F16B31/04
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
125 words
In a combination of a ground formation wherein an inner surface constitutes a borehole extending from an outer surface thereof, a rock bolt, and means affixing said rock bolt to said ground formation, said rock bolt having an elongated portion thereof disposed within said borehole in longitudinal alignment therewith, said portion being a rod element having a substantially uniform, generally circular cross-sectional area and a form characterizable as a flexible helix of a substantially uniform diameter throughout and a pitch that is large relative to a diameter of said rod element wherefore the spring index of said rod element is greater than 2, and said means affixing comprising first and second means securing said bolt to said inner and outer surfaces of said formation, respectively.
Claim 2
Dependent Claim
125 words
In a combination of a ground formation wherein an inner surface constitutes a borehole extending from an outer surface thereof, a rock bolt, and means affixing said rock bolt to said ground formation, said rock bolt having an elongated portion thereof disposed within said borehole in longitudinal alignment therewith, said portion being a rod element having a substantially uniform, generally circular cross-sectional area and a form characterizable as a flexible helix of a substantially uniform diameter throughout and a pitch that is large relative to a diameter of said rod element wherefore the spring index of said rod element is greater than 2, and said means affixing comprising first and second means securing said bolt to said inner and outer surfaces of said formation, respectively.
Claim 3
Dependent Claim
16 words
The combination of claim 1 wherein said spring index is from about 2.3 to about 2.8.
Claim 4
Dependent Claim
80 words
The combination of claim 1 wherein said first means securing includes a mass of flexible grout packed between said rod element and said inner surface of said ground formation and an anchor means at an end of said rod element within said borehole, and said second means securing includes a plate on an end of said rod element outside said borehole and in contact with said outer surface, and a nut on said outside end normally bearing against said plate.
Claim 5
Dependent Claim
22 words
The combination of claim 1 wherein said pitch of the helix is from about 10 to about 20 times said rod diameter.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1979-03-09 | 1979-09-08 | 1980-03-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-03-09 | 1983-09-08 | 1984-03-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-03-09 | 1987-09-08 | 1988-03-09 | $7700.00 | Window Closed / Lapsed |