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By R. A. Metz, Isaac Vera, Hans Ruge

The El Soldado copper mineralization occurs as relatively high-grade irregular ore bodies with assay contacts and with frequent inclusions of barren rock. The sampling methods must be timely for production grade control purposes, as well as accurate and inexpensive. Sampling techniques evolved from sampling dump cars at the haulage level to sampling Scooptrams at the loading pockets. These methods were abandoned in favor of sampling production blastholes. Several sampling alternatives are discussed. These involve the selection of optimum volumes and sampling frequencies while taking into consideration geological parameters and statistical analyses of sampling data.

Jan 1, 1992

By D. M. Cregger, J. L. Rosenblad, R. E. Ranken

The construction of a large span, high-walled underground opening in a low strength shale rock is unprecedented. The feasibility of constructing a pumped storage project with several tunnels and a large underground powerhouse in low strength shale rested largely on the feasibility of building stable openings large enough to accommodate the required equipment. Because of the lack of experience with large openings in shale, the decision was made to excavate a test adit and test chamber and conduct a multi-faceted geotechnical evaluation program designed to yield pertinent in-situ data on the ability of the shale to accommodate a large underground opening. Factors considered in the shape, size, orientation, and location of the test chamber were: (1) similarity to the anticipated powerhouse chamber, (2) nature of the most important data to be obtained, (3) feasibility of construction, and (4) economics.

Jan 1, 1983

By Gary S. Brierley, Ronald E. Romley, Alan L. Howard

The Price Road Drain Tunnel in Tempe, Arizona is part of the drainage system constructed in conjunction with the Outer Loop Highway in metropolitan Phoenix. The Outer Loop Project is a part of a much larger expressway system that includes other large drainage tunnels such as the Papago Freeway Drain Tunnels. Large diameter downhole inspection borings were utilized to obtain subsurface data for the design of these tunnels. Subsurface data obtained from the large diameter borings resulted in the development of empirical parameters that were successfully incorporated into the Geotechnical Design Summary Report and which satisfactorily predicted ground behavior, formed the basis for improved geotechnical design criteria, and facilitated the cost effective assessment of third party risk. The purpose of this paper is to describe the subsurface exploration program performed for this project and to explain the methods used to evaluate underground construction procedures.

Jan 1, 1991

By W. D. Monaghan, A. J. Kwitowski, A. L. Brautigam

Teleoperation is a technology that can provide significant health and safety improvements in mining operations by locating machine operators hundreds of meters away from the face area. The US Bureau of Mines recently developed a teleoperation system for continuous mining and haulage equipment. This system features near real-time closed-loop control. A prototype system was developed and demonstrated. This system could be used in thin-seam applications down to 36 in (914 mm). Provided are details of the teleoperation system, the results of testing and the expected applications of this technology.

Jan 1, 1996

By Jean-Pierre Nossereau, Allen J. Hulshizer

The main thrust of this paper covers the design, installation techniques and experience associated with the installation of eleven 1.5 m (4'-11") and three 2.87 m (9'-5") diameter shafts in 15 to 23 meters (50 to 75 ft) of water over 1.6 Km (a mile) out in the Atlantic Ocean. The approach implemented, permits the use of pre-fabricated shaft linings and incorporates a safe dry-tap method for connecting the offshore shafts to tunnels driven blind from deep land shafts over 4.8 Km (3 miles) away. This tunnel-shaft system is a unique venture employed at the Seabrook Nuclear Power Station to meet plant cooling water requirements.

Jan 1, 1981

By E. D. Goddard, D. S. Murphy

Acid resistance, zeta potential and ESCA (electron spectroscopy. for chemical analysis) experiments were performed on emperador marble and four calcium carbonate samples (onyx calcite, travertine calcite, Iceland spar calcite and aragonite). Six fluorine-containing reagents were used to treat the surfaces of these materials: magnesium hexafluorosilicate, zinc hexafluorosilicate, sodium fluoride, zinc fluoride, strontium fluoride and stannous fluoride. The acid resistance of treated samples proved to be much higher than that of their untreated equivalents. The isoelectric point of treated samples approaches the isoelectric point of fluorite. Also, the fluorine content, as measured by ESCA, of a marble surface treated with magnesium hexafluorosilicate is much higher than that of an untreated sample. The binding energy off of fluorine and calcium the treated marble is consistent with the formation of calcium fluoride.

Jan 1, 1994

By T. D. Rourke, Fred H. Kulhawy, O&apos

From mid-1976 to early 1978, a 5.64 m diameter tunnel, 2491 m long, was excavated by a modified Robbins full-face TBM under shallow cover in highly stressed sedimentary rock in Rochester, NY. In-situ stress measurements were made, and tunnel behavior was monitored with MPBXs, inclinometers, tape extensometers, and instrumented steel ribs. Detailed geologic mapping was also done. In this paper, the as-monitored tunnel behavior is described, and the TBM performance is evaluated from field records. Recommendations are also made for future tunneling in similar geologic environments.

Jan 1, 1981

By Lee W. Abramson, James E. Crawley

Caltrans is studying alignments for a 160-kilometer-long high speed ground transportation system from Los Angeles to Bakersfield across the Tehachapi Mountains. This link is needed to connect southern California with San Francisco by a short passenger rail service. None presently exists. The system will require tunnels and viaducts along the route with sections crossing two major active fault zones. High speed ground transportation technologies are being evaluated for achieving rail speeds of between 200 and 480 kilometers per hour. This paper presents the technical requirements for tunnels along the alternative routes being considered for the project.

Jan 1, 1995

In 1993, the United States' economy grew at a rate of about 3%. The Gross Domestic Product rose to $6.4 trillion. With more than 258 million people - 599,000 in mining including petroleum - the United States has more than 100 million dwelling units and more than 190 million licensed motor vehicles. New private housing starts rose 7% to 1.3 million units, new car production fell 3% to 5.5 million units and truck and bus production rose 21 % to 4.9 million units. The rate of inflation was under 3% and the prime rate of interest 6%. The Producer Price Index (1982 = 100) was unchanged from 1992 for fuels and re¬lated products and power at 80 and met¬als and metal products at 119, while chemicals and allied products rose 2% to 128 and non-metallic mineral prod¬ucts rose 2% to 120. The merchandise trade deficit rose 27% to $116 billion.

Jan 1, 1994

By William R. Groseclose, Kenneth D. Schoeman

The Buckskin Mountains Tunnel is a key link in the Bureau of Reclamation's Central Arizona Project. The 22-foot (6.7-m) diameter tunnel is being bored in a north-northwesterly direction through volcanic rock near Lake Havasu in western Arizona. The 6.9-mile (11-km) conveyance tunnel will carry up to 3,000 cfs (85 cu m per sec) of water through the Buckskin Mountains as part of the Granite Reef Aqueduct. The water for the project will be drawn from Lake Havasu behind Parker Dam on the Colorado River and pumped some 800 feet (244 m) above the lake to the inlet portal of the free flow tunnel where it begins its 190-mile (300-km) journey to Phoenix, Arizona, and beyond into Orme Reservoir (figure 1). Precast concrete segments are being used as a single system initial support and final lining in the tunnel being excavated by a tunnel boring machine specially designed and built for the job by The Robbins Company. J. F. Shea Company, Inc., of Walnut, California, is constructing the tunnel for the Bureau of Reclamation.

Jan 1, 1976

By William E. Foreman

The results of the electrokinetic study of the activation of quartz by divalent cations showed that the charge reversal was related to the point at which the cation hydrolyzed. The reversal was not due to the presence of solid hydroxide at the surface of the quartz but due to the charged ions in the solutions. The charge reversal for beryllium at a log molar concentration of 1x10-4 was observed at pH 5 and 9. The quartz was positively charged between a pH reading of 5 to 10. Magnesium at the same log molar concentration did not show a charge reversal from pH 2 to 12. The probable cause of the charge reversal was due to the ionized Be3 (OH)3+3 or Mg (OH)+ . Variations in the electrokinetics of quartz were minimized by heating the sample to 300° C.

Jan 1, 1968

By Jamai Rostami

Mining, perhaps more than other industries, has been under pressure to achieve higher productivity, while reducing costs and environmental impacts. This has encouraged a move toward large-scale operations and greater integration and automation of systems. Mechanization is being used increasingly to raise production and reduce labor requirements. Yet, while transportation, ventilation and other activities have benefited from this trend, mechanization of rock excavation (for development and production) has lagged. The switch to a mechanized excavation system can be complex, requiring a thorough study of operational and cost benefits to be successful. To justify the high capital cost of mechanical mining equipment, production rates and the true costs of machine mining must be accurately estimated. To evaluate the cost effectiveness of mechanical mining for a particular operation, the total production cost (capital and operating) must first be estimated. This requires a reliable estimate of the production rate of the candidate mechanical excavator. Previously, the variable nature of rock caused performance prediction of these machines to be more an art than a science. Additionally, some of these machines are highly sensitive to operator skill. They all depend on their backup systems. The effects of interaction with the overall mining operation can be difficult to forecast. And a new system must surmount psychological barriers before it can become truly operational.

Jan 1, 1994

By Norm Steenson

Rapid excavation includes rapid support and is the central theme of this paper. Over the last few years, enormous strides forward have been made in the excavation and material handling aspects of underground excavation. However, the technology necessary to support these rapidly created openings has lagged behind the other aspects. This paper would attempt to bring you up-to-date on the progress made in bringing ground support using shotcrete into the same productivity rates as the other cyclic operations. Shotcrete has become an acceptable material for temporary and permanent support for undergound openings. However, coarse aggregate shotcrete has been an expensive construction material. It has been confined in the main to difficult ground conditions where conventional methods of support have proved to be even slower and more expensive than shotcrete. There are two main factors influencing the productivity of shotcrete equipment. (1) Structural shotcrete as opposed to gunite requires 40% to 45% rock minus 3/4" in the mix design. The equipment to handle such aggregate content has been difficult to develop on a volume basis owing to the attritional nature of the material which causes intense wear problems on

Jan 1, 1974

By Evans U. Jegbefume

A plane strain two-dimensional finite element model employing the method of negative reaction loading has been used to model roof collapse and subsidence resulting from the underground gasification of coal in regions of soft overburden such as that found in Texas. The model included dry zones of rock around the cavity. Roof collapse was included by considering the final state of stress in the elements and removing those that had undergone tensile failure. The two-dimensional plane strain model was extended to include thermal loading and thermal softening of the roof rock. Roof collapse initiation and growth of the cavity were modelled by examining the portion of the rock immediately above the cavity under thermal and hydrostatic load. The model was extended to include linear creep using the method of incremental strains. The overburden was modelled as a generalized Kelvin material.

Jan 1, 1982

By Yutaka Mochida

OUTLINE Beginning in 1946, a careful geological survey was made of the Tsugaru Straits. In 1964, excavation of the exploratory tunnels were started to observe the characteristics of faults and rock formation directly, and to study construction methods of excavation and sealing water inflow. In March 1971, the investigation stages were over, and in April 1971, the construction project was authorized from the government. The geological features in the straits may be divided into three broad classes. One third consists of andesite on Honshu side. The other two thirds consists of tuff. The middle of the straits consists of tuff, so-called Kuromatsunai-layers. On Hokkaido side, it consists of tuff, called as Kunnui-layers. There are nine noteworthy faults on the route. Prior to the excavation of the main tunnel, the horizontal pilot tunnels and service tunnels are made. Exploratory borings are taken to confirm the geological conditions and the presence of gushing water. Groutings for sealing water inflow are carried out when necessary. In geologically bad conditioned sections such as disintegrated or fractured zones, special methods are applied. In geologically good zones, the tunnels are bored through using the same methods as for a mountain tunnel driving. The pilot tunnel being constructed at the sea bottom is under direct control of the Japan Railway Construction Public Corporation. The service tunnel and the main tunnel are being excavated by contractors.

Jan 1, 1981

By Robert F. Hauck

This chapter discusses a new technology for computer control in open-pit mine operations: the real time automatic dispatching of manually driven trucks to shovels. The monitoring of truck activity is accomplished by detection of local radio signals. Computer-operated directives are communicated to drivers by remote controlled digital display units inside the truck cab. The production objective is to maximize tonnage in a cost effective manner. The problem is formulated in the appendix and the solution method is briefly described. Side conditions such as maintaining delivered ore grade aims, balancing waste to ore volumes to keep within stripping ratio tolerances, and meeting production rate requirements temporarily established for certain shovels are also discussed. Experience with a developed event- to-event simulator applied to analyses of several North American mining operations using this technique is summarized. Complete systems employing this technology are now under- going installation at mine sites in Canada and the United States.

Jan 1, 1979

By S. Shrivastava, R. G. Reddy

Spent potliner is generated in the electrolytic process of reducing alumina to make aluminum metal using molten fluoride electrolytes. Spent potliner(SPL) is obtained at the end of the pot's life. The SPL contains small amounts of cyanide and fluoride, which present environmental problems. Spent potliner could possibly be used as a fluidizer to replace calcium fluoride (CaF2) in the iron- and steelmaking industry and in the glass industry. A low viscosity and a low melting point are prime requirements for such an application. In the present study, viscosity measurements were performed. The effects of various additives, such as sand, limestone, dicalcium silicate dust and MgO baghouse dust, on the viscosity of SPL were studied. The results showed that the addition of sand and limestone can produce a very high fluidity SPL melt at significantly lower temperatures. The results suggest that spent potliner mixed with additives could potentially be used as a substitute fluidizer.

Jan 1, 2002

By Harold G. Arthur

INTRODUCTION Stillwater Tunnel construction is scheduled to start in the spring of 1973. The tunnel will be the site of an extensive program in rapid excavation research. This paper presents a progress report regarding our plans and relates the tentative decisions which have been made on how to carry out the research effort. The details are subject to revision as more input is obtained from other Government agencies interested in tunnel construction and from experts in industry and educational institutions. The objective of the research program is to bring about faster, less costly tunnel construction. This objective will be pursued through the development, improvement, and evaluation of various construction systems and investigative techniques. The need for this kind of program was recognized by the National Research Council, in its authoritative report "Rapid Excavation - Significance, Needs, Opportunities." (1) The Council advocated a federally funded $200 million, 10-year program to help meet the $69 billion market it expects in underground excavation between 1970 and 1990. The significance of tunnel construction to Reclamation is made clear by statistics of its tunneling experience and outlook. Reclamation has constructed 174 water conveyance tunnels totaling over 190 miles, Six tunnels are presently under construction which have a combined length of about 27 miles. There are on the books nine authorized, but unfunded tunnel projects totaling another 70 miles in length. Many more miles of tunnels are included in programs in various stages of investigation.

Jan 1, 1997

By Harold Wagner, Prakash Donde, Larry H. Heflin

INTRODUCTION The Washington Metropolitan Area Transit Authority is responsible for the planned 166 kilometer (103 mile) Metro rapid rail transit system in Washington, D.C. Some 117 kilometers (72.8 miles) of this system is in operation and contains 30.6 route-kilometers (19 miles) of rock tunneling. To complete the planned system an additional 1.6 kilometers (1.0 miles) of single track tunnels in rock are planned and additional contracts will consist of 4 kilometers (2.5 miles) of twin tunnel, resulting in 8 additional linear kilometers (5 miles) of single track tunnel contracts yet to be offered in soft ground. Three recent contracts in soft ground included the New Austrian Tunneling Method (NATM), along with conventional tunneling, as a bid option. Section E5a, Fort Totten Station and Tunnels, was the only one of the three to be constructed using the NATM option. This is the first application of the New Austrian Tunneling Method in soft ground in the United States. This paper will concentrate on the Fort Totten Station chamber NATM design, construction, and the instrumentation readings and evaluations which lead to an engineering back analysis which allowed a refinement of the bid design, resulting in a faster, more efficient construction. Design of the Fort Totten Station and Lines was done by Sheladia Associates. The design team included Greiner Engineering and Jenny Engineering with Mayreder-Consult of Austria, who was responsible for NATM design and NATM construction consultation.

Jan 1, 1991

By N. S. P. Kumar

INTRODUCTION Development work at Carr Fork Mine of Anaconda Copper Company in Tooele, Utah commenced in August 1974. A decision to install an underground gyratory crusher for primary crushing run-of-mine ore and waste was made in 1976. Higher throughput rates, larger reduction ratios and greater flexibility in terms of meeting immediate and expanded production needs were the main reasons for selecting the gyratory crusher over the jaw crusher. UNDERGROUND MATERIALS HANDLING Underground crushing and conveying system was designed for a capacity of 16,300 mtpd of ore and waste on a 2-shift, 5-day week basis. Engineering and design of crusher complex was performed by Anaconda engineers at Carr Fork. Figure 1 represents the longitudinal section of mine showing the general materials handling system. Mine area is trackless except for materials and production haulage which is run on rail track on both 1200 and 970 levels. Ore from stopes and waste rock from development headings are handled by 3.8 cu m (5 cu yd) Jarco scoops and dumped into 2.4 m (8 ft) diameter ore and waste passes at the 1200 level. The material gravitates down to the 970 level where it is loaded into 12 cu m (420 cu ft) ASEA mine cars using side loading chutes. The muck train, consisting of 15 to 18 cars and two 27 mt General Electric trolley locomotives, is hauled over a distance of 2,300 m (7,550 ft) to

Jan 1, 1981