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By Yuji Tsuneno, Yoshikazu Mikami, Yasuo Takeuchi

A new device was successfully developed in order to overcome the difficulty of drilling longer holes for anchors in soft soil bedrocks or swelling bedrocks, which is one of the major impediments to rapid excavation by NATM (New Austrian Tunnelling Method). With higher rotation (1200 - 1800 r.p.m.) and lower percussion energy (4 - 6 kg.m), the new drill has following advantages: (1) Applicability covers soils and medium hard rocks with the same drifter. (2) Longer hole (more than 9m) is achievable only with air flushing even in cohesive soils or rocks. (3) Better borehole stability is obtainable even in earth or in fissured rocks.

Jan 1, 1981

By D. E. Hart, A. R. Walsh, Derek Maishman

In order to safely construct a ventilation and escape shaft through saturated overburden into an operating mine, artificial ground freezing and raise boring were combined for the first time on a project in the U.S.A. at Georgia-Pacific's Kentwood Mine in Grand Rapids, Michigan. Previous to drilling a pilot hole 206 feet deep into the mine, a 20 foot diameter cylinder of soil 140 feet deep was totally frozen. Before termination of the freezing operation, the pilot hole was reamed to 9 foot diameter and a 7 foot inside diameter hydrostatic steel liner was grouted in place.

Jan 1, 1991

By James R. Aggson, Verne E. Hooker, Dennis R. Dolinar

The stability of underground openings and mining systems is closely related to the in situ stress field. This paper presents a short discussion of the three-component borehole deformation gage and overcoring technique which the Bureau of Mines uses to measure in situ stresses, and a summary of stress data that the Bureau has gathered in the process of evaluating ground control problems. Specific ground control problems and stress distributions are discussed as examples.

Jan 1, 1982

By Thomas A. Lang, Kanwarjit S. Chawla, Francis S. Kendorski

Unlined water tunnels have often been used as pressure conduits for hydroelectric projects. However, fallouts of rock in such tunnels are not uncommon and in many cases have been attributed to erosion of shears and seams. A case history of such a fallout is described. An appraisal of the conditions pertaining to the fallout led to the conclusion that rapid changes in the water pressure in the tunnel resulting from operating conditions were significant factors in initiating the fallout. Other factors that contributed to the fallout are also described.

Jan 1, 1976

By Ph. Vandebrouck

SUMMARY In August 1986, TRANSMANCHE LINK, a joint venture comprising the 10 companies who initially promoted the project, signed a contract with EUROTUNNEL for the design, construction and commissioning of the TRANSMANCHE fixed link for an amount of 4,5 billion dollars. On the French side, the work consists of digging three, 19km. long tunnels, of which almost 16 kms. are under the sea, up to the meeting point with the Tunnel works carried out by the British.. The tunnels are bored through chalk by 5 tunnelling machines, starting from one intermediate point at Sangatte near the coast: - Landward, they are drilled trough permeable strata of white and grey chalk. - Seaward, mainly through relatively impermeable chalk marl, but with the presence of water in faulted zones, or in grey chalk.

Jan 1, 1989

By Barry J. Hansen, Ruston A. Ford

Production of mine backfill from the tailings produced in a proposed Crandon concentrator is described. A process has been developed capable of producing suitable fill for the mining method selected for the Crandon orebody. It maximizes the placement of pyrite underground as fill and segregates tailings into pyrite and nonsulfide fractions. To determine the suitability and engineering characteristics of the backfill product for use underground, laboratory and physical stope simulation model testing was conducted. The results of the testing and the application of those results to the design of the backfill system ultimately affecting mine geometry and subsequent mine production will be presented.

Jan 1, 1981

By Bezalel C. Haimson

Long before excavation begins, the in situ stresses in the horizon of planned underground chambers can be measured by employing the hydrofracturing technique in existing exploratory holes. Such measurements produce the stress magnitudes and directions required for the rational design of rock structures. Two recent case histories are cited in which preexcavation stress measurements for the design of underground powerhouses proved very beneficial in the orientation of the chambers and the estimation of the stability and required support. A third stress measurement case is related to the preexcavation design of tunnels that will house doughnut-shaped superconductive magnets for the storage of electric energy. In all cases, expensive later modifications were probably prevented by measuring stresses early in the design stage.

Jan 1, 1976

By Manuel Diaz del Rio

At the present time there are over 5,000 Kms of railway tunnels in existence throughout the world. In many cases these tunnels were built over a century ago using techniques obsolete today. Supervision and maintenance of these tunnels is essential to the economy of each country involved. For this purpose an electro-optical measuring system has been designed incorporating highly complex soft and hardware (15 mW laser, high resolution TV camera and processing computer), mounted on a vehicle. Its job is to scan, record and compare sectional gauge values (profiles) and strains inside tunnels both momentarily in situ and on permanent record, as an aid to the supervision work. From the state of the strains observed, in conjunction with an infrared spectrum of the tunnel lining and soil involved, the mechanical stresses in the tunnel can be deduced by applying the boundary elements method.

Jan 1, 1981

By Allyn J. Steward

The 14,350 m (47,000 ft) Mount MacDonald Tunnel is nearing completion. North America's longest railroad tunnel is being advanced from each end by two contractors. This presentation outlines techniques employed by the Manning Kumagai Joint Venture, working from the west portal. Rapid construction was achieved by simultaneous installation of cast in place arch-wall lining and drill and blast excavation. Extensive planning, judicious choice of equipment and efficient crews combined to shorten the original schedule. Manning Kumagai was also awarded the tunnel mid-section as a separate contract. This includes construction of an underground chamber and structure for a unique permanent ventilation system.

Jan 1, 1987

By Terence G. McCusker

Precast concrete segmental tunnel linings have been used since at least 1903. More serious attention was devoted to them in England during the World War II steel shortage and they have become increasingly common since that time. They are now coming into common use in the United States, especially as primary linings for soft ground tunnels and for rock tunnels in poor ground, although they have also been used as final lining, especially in rock tunnels. The developmental logic, design considerations, and current practices are examined. Particular attention is given to unbolted linings, with and without secondary linings. Probable future developments are considered.

Jan 1, 1989

By Jack Bradbury

The open stope room and pillar method of mining is used throughout Ozark Lead Company's underground mine located at Sweetwater, Missouri. This method of mining produces an approximate overall ore extraction of 80%. Pillar recovery, on a limited and experimental basis, was started in January of 1979 to determine the maximum size underground opening that could be mined safely. Monitoring the roof and surrounding pillars for potential failure during this pillar recovery process was accomplished by utilizing a simple rod extensometer to measure roof sag. Boreholes 7.5cm in diameter were drilled 3.5m into the roof to spot any separations or cracks that might have propagated between the bedded layers of rock. Underground openings 85m in length by 46m in width have been mined successfully without roof or surrounding pillar failure. Continued measurements to establish long term results will be necessary.

Jan 1, 1981

By Dave Watson

Henderson Mine personnel have more than 20 years experience and have placed more than 400,000 m3 (520,000 cu yd) of shotcrete and concrete. Over the last 20 years, the mine has used a variety of equipment to place concrete, wet shotcrete and dry shotcrete and is constantly trying to cut costs and increase efficiencies. Recently, the mine received a state-of-the-art wet shotcrete placer. The batch plant was automated, and a mobile concrete-form jumbo was fabricated. The mine will also receive a new concrete transport truck. Henderson’s background The Henderson Mine is owned by Climax Molybdenum Co., a unit of Amax, Inc. It is an underground, primary molybdenum producer near Empire, CO. The mill is located between Silverthome and Kremmling, CO and is connected to the mine by 16 km (10 miles) of underground and 8 km (5 miles) of surface track. Except for the ore haulage system which is powered by overhead trolley, all mobile equipment is rubber-tired and diesel-powered.

Jan 1, 1992

By Chris C. Sundberg, Ronald E. Heuer, Stanley L. Paul, Peter M. Douglass

Use of prestressed concrete cylinder pipe (PCCP) for pressure tunnel liners is gaining popularity with contractors, engineers, and owners. This paper presents loading considerations and a beam-spring computer model approach to tunnel liner analysis, together with ultimate strength (US) and service load (SL) procedures for liner design. The US procedure is best suited to check for adequate liner strength under extreme loading conditions. The SL procedure, based on conventional pipeline design practice, is considered more appropriate when addressing crack control and serviceability under normal working load conditions. Other design and construction considerations are discussed and a design example is presented.

Jan 1, 1987

By Michel Grenier, David A. Young, Brent Rubeli, Mahe Gangal

This work forms part of a study being conducted into the feasibility of constructing a prototype Load Haul Dump (LHD) vehicle for operation in underground Canadian mines. A series of in-laboratory assessments were performed to determine the relative contributions of a Deutz F4L912W (54 HP- conventional vehicle engine) and a Deutz F2L 2011 (31 HP hybrid vehicle engine) to diesel emissions concentration during mine transient duty cycles and steady-state operating modes respectively. Results indicate significant reductions in the quantity of gaseous and particulate emissions with the application of the hybrid system and a high-efficiency ceramic element filter. This paper describes the engine test protocols and the results of this laboratory study.

Jan 1, 2006

By Edward DeLilla

Formalized technical audits for mining machinery during manufacturing are a fairly new concept to the North American mining industry. Although used extensively elsewhere, especially in Australia, the concept of independent auditing of machinery design and manufacturing has been slow to gain acceptance in the United States and Canada. Simply stated, a technical audit is an independent, third-party review of all or specific portions of machinery design, manufacturing and assembly to verify compliance with purchase specifications and suitability of the machinery for the specified application. If specified correctly, the useful life of different kinds of structural and mechanical components can be extended beyond normally accepted usage. There is no reason why, if properly designed and built for the application, major structural components on mining machinery cannot be made to last for 20 years before being rebuilt. Also, gearing can be made to routinely last for 15 years.

Jan 1, 1995

By Wolfgang H. Roth, Stephen J. Navin, Samuel K. Louis, Anthony F. Stirbys

This paper presents a case history of the design and construction of the access shaft and cross adit utilized to gain access to the Los Angeles Metro Rail tunnel alignment, at the A146 Contract site. The access shaft, a 14 m (45 ft) inside diameter structure, was constructed using ring beams and lagging with concrete backfill to a depth of 18.59 m (61 ft). The cross adit was hand excavated in sequential benches using liner plate, arch ring beams, and posts for support. The sequence of excavation and support placement are discussed. Soil conditions encountered at the project site are discussed together with the development of the design criteria. Instrumentation data collected during the excavation are also presented.

Jan 1, 1989

By J. Patrick Powers, Arthur B. Corwin

Modern improvements in hydrogeology make it possible to predict with good reliability the performance and cost of ground water pumping systems in many tunneling situations. The testing and analysis techniques are presented. Data from the Buffalo NY LRRTS (1978-1980) illustrate the successful application of the technique for tunneling in rock. Data from the Red Hook Interceptor Tunnel in Brooklyn NY (1978) illustrate the application in soft ground. The Red Hook project also illustrates concerns for the side effects from dewatering, such as ground settlement and damage to timber structures. At Red Hook protective measures included compressed air, artificial recharge and controlled dewatering. Given the uncertainties of the underground, the possibility of unexpected situations must be considered. A hard rock sewer tunnel in Atlanta, Georgia (1982) illustrates an unexpected problem, and the emergency measures used to solve it.

Jan 1, 1985

By Michael E. Allen

The building of sanitary and storm drainage sewers in urban or environmentally sensitive areas often requires the use of tunnel construction procedures. While hydraulic considerations may require only small diameters, traditional tunneling techniques make small sizes the least economical. Current state-of-the-art techniques using highly mechanized systems of pipe jacking can provide cost effective solutions to the problems of construction of small size tunnels. The characteristics of mechanized pipe jacking allow rapid advances under difficult ground conditions. The basic pipe jacking cycle is used with a variety of excavation systems to permit the contractor to satisfy engineering as well as economic parameters. These characteristics and several of the systems available are outlined.

Jan 1, 1981

By R. J. Pruett, P. I. Prescott

Ground calcium carbonate (GCC) is used in the paper, plastics, paint, rubber and caulks and sealants industries. The favorable properties of GCC include high whiteness and brightness, low hardness and outstanding rheology in water systems. The quality of calcitic GCC ores, which includes chalk, limestone and marble, is dependent on calcite purity and the nature and quantity of the impurity minerals. Wet and dry grinding are used in the processing of GCC. Ore processed by optical sorting, flotation and/or particle-size classification has higher brightness and lower abrasion characteristics. GCC markets are a function of the product's properties, purity and cost.

Jan 1, 1997

By M. Polat, S. Chander

Many models have been suggested in the past to obtain a satisfactory fit to flotation data. Of these, first-order kinetics models with a distribution of flotation rate constants are most common. A serious limitation of these models is that type of the distribution must be pre-supposed. Methods to overcome this limitation are discussed and a procedure is suggested for estimating the 'actual' distribution of flotation rate constants. It is demonstrated that the classical first-order model fits the data well when applied to coal flotation in narrow size-specific gravity intervals. When applied to material which is fractionated on the basis of size alone, the use of three parameter models, which were modified from their two parameter analogs such as rectangular, sinusoidal, and triangular, gave most reliable results.

Jan 1, 1995