Precast concrete liners for blind-drilled shafts

Abstract Technology exists today to blind drill a mine shaft 20 feet in diameter, unlined, over 3,000 feet deep. These shafts must be lined in the most economical, safe and expedient manner possible. A new technique of stacking precast concrete cylindrical sections in the unlined shaft has been developed to yield a dry and hydrostatically lined shaft.These sections must withstand an external radial pressure of 3,000 feet of water yet take up as little room as possible in the shaft. Using high-strength concrete, wall thicknesses may be kept at 2 feet. The outside diameter of the sections has been chosen to be 18 feet to allow for some annular space between the liner and shaft wall. The concrete sections are produced in segments 10 feet long weighing 75 tons each.During drilling operations, the concrete sections are cast and cured. After drilling operations are complete, a head-frame is situated over the shaft. The unlined shaft remains full of fluid. A special liner running tool is mated with the section in three steel ports at the bottom of the section. The section and running tool are lowered into the hole, and the tool is disconnected and returned to the surface. Subsequent sections are lowered and stacked using the same operation. Grout is placed behind the liner to result in a dry shaft.
Keywords: Shaft sinking, Shaft drilling, Blind drilled shafts, Liners, Concrete liners, Precast concrete, Hydrostatic pressures.
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Summary: This paper describes the Sasol coal liquefaction process, as used in South Africa. It covers coal supply, coal gasification, gas purification, Fischer-Tropsch synthesis, the major utility systems involved and the economics of the process.
Publication: CIM Bulletin
Author(s): M.M. PAPIC
Keywords: Coal liquefaction, Sasol process, Synthesis, Fischer-Tropsch synthesis, Gasification, South Africa, Gas purification.
Issue: 830
Volume: 74
Year: 1981
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Summary: The gravimetric dust sampler is one of the tools now available to the industrial hygienists for determining the worker's exposure to the numerous types of paniculate matter that may be present in the workplace. The paper reviews the different sampling trains that can be used for the two major criteria for respirable dust and some of the sources of error in this dust assessment technique.
Publication: CIM Bulletin
Author(s): W.A. BARDSWICH
Keywords: Environmental control, Dust sampling, Gravimetric dust sampling, Konimeters, Impingers, Sampling.
Issue: 830
Volume: 74
Year: 1981
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Summary: The main solution, ore and residue pulp streams in the Rio Algom Quirke I uranium mill at Elliot Lake have been sampled and analyzed for radium-226. Analysis of the ore and leached residues indicates that Ra-226 dissolves and precipitates within the first pachuca tank. A maximum of approximately 0.2% of the Ra-226 in the ore remains in solution during leaching.
Publication: CIM Bulletin
Author(s): J.M. SKEAFF
Keywords: Radium, Rio Algom Ltd., Quirke mill, Elliot Lake, Leaching, Acid drainage, Radionuclides, Uranium tailings, Ore processing.
Issue: 830
Volume: 74
Year: 1981
Text
Summary: The detection and quantification of the degree of weathering is an important aspect of coal exploration and mining. Tests for weathering which are suitable for the exploration camp should be fast, simple, and require minimal equipment and operator expertise. In this study, two tests which fulfill these requirements were evaluated using samples of Western Canadian coals. These tests, one based on the pH of a coal slurry and the other on the flotation of coal in a water/diesel oil mixture, do...
Publication: CIM Bulletin
Author(s): D.L MARCHIONI
Issue: 830
Volume: 74
Year: 1981
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Summary: The efficiency of operation and life of an advancing longwall coalface depends, to a great extent, on the face-end roof strata conditions and the stability of the gateroads. The factors that influence the rate of closure of gateroads are examined, in particular the gateside pack and the coal rib (crush) pillars. The performance of mechanized packing systems is briefly discussed. Gateroad deformation surveys were carried out at two coal mines to determine the influence of the rib pillar width...
Publication: CIM Bulletin
Author(s): TONY B. SZWILSKI
Keywords: Coal mining, Pillars, Rib pillars, Ground control, Longwall mining, Gateroads, Packing systems, Roof control.
Issue: 830
Volume: 74
Year: 1981
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Summary: Shaft sinking by blind shaft drilling offers the mining industry a different approach to shaft construction. Benefits of blind drilling include less construction time and fewer safety problems while being economically competitive with conventional sinking methods under certain conditions in soft water-bearing formations.Technology and equipment are available today to drill blind shafts up to 20 feet in diameter and over 3,000 feet deep. This is an extension of proven techniques developed by...
Publication: CIM Bulletin
Author(s): R.P. CARONE, D.A. WHITLEY
Keywords: Shaft sinking, Drilling, Shaft drilling, Blind shaft drilling, Rotary drilling.
Issue: 830
Volume: 74
Year: 1981
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Summary: Whitehorse Copper is a 2600-ton-per-day underground copper mine located within the city limits of Whitehorse, Yukon. In early 1978, due to increasingly difficult ground conditions, it was decided to investigate the conversion from longhole open sloping to vertical crater retreat mining. On-site crater testing by C-I-L demonstrated the feasibility of V.C.R. mining at Whitehorse Copper.After some investigation, a down-the-hole drilling rig was chosen and drilling began in November 1978....
Publication: CIM Bulletin
Author(s): J.J. JANSSENS, P.W. PERCIVAL
Keywords: Underground mining, Vertical crater retreat mining, Soft ground, Whitehorse Copper Mines Ltd., Drilling, Blasting, Loading.
Issue: 830
Volume: 74
Year: 1981
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Summary: An initial test of this unique application demonstrated that hot gunned refractory would adhere satisfactorily. Subsequently, it was found that the proportion of material sticking during application increased with increased vessel temperature and when a mix containing pitch was used. About 75 per cent of the latter type adhered when it was applied at 1600°C.TBRC availability increased from an historical average of 62.5 per cent to 64.7 per cent during four campaigns when hot gunning was...
Publication: CIM Bulletin
Author(s): W.J. THOBURN, M.R. ALBERTY
Keywords: Process metallurgy, Gunning, Inco, Refractories, Converters, Top Blown Rotary Converter, Refineries, Nickel refining.
Issue: 830
Volume: 74
Year: 1981
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