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By George Mylonakis

The curvatures and subsequent bending imposed to piles by the surrounding soil during the passage of strong seismic waves is studied. This type of bending develops even in the absence of a superstructure and is referred to as "kinematic bending", to distinguish it from bending imposed to piles by loads generated from the inertia of the superstructure ("inertial bending"). Although kinematic loading may be severe in the presence of sharp stiffness discontinuities in the profile and may lead to damage, it has received little attention by engineers. The scope of the paper is twofold: (i) to discuss some fundamental aspects of seismic pile bending, and (ii) to review some existing design methods. To this end, a dimensionless bending strain parameter (instead of the more commonly used bending moment), and a strain transmissibility function relating pile bending strain and corresponding soil shear strain are introduced. Numerical examples are also presented.

Jan 1, 2002

By Martin Herrenknecht, Karin Bäppler

The last five years have seen a remarkable increase in tunnelling projects in both soft ground and hard rock applications. Part of the increase is a result of recent Research & Development efforts to improve Tunnel Boring Machine (TBM) adaptability, capability and reliability. This paper will review the latest innovations in the TBM industry and explain in detail the results of these innovations followed by a forecast where the technology will take the tunnelling industry in the future.

Jan 1, 2005

By A. Sutton-Pratt

The African continent has been the most prolific producer of gold since mining began. Although most of this gold has come from South Africa, other countries have also been important contributors in the past. There is currently little production outside South Africa, Ghana and Zimbabwe, but the gradual globalisation of the industry over the past decade has resulted in growing interest in the region which bodes well for its future development. An outline is given of prospects and activity (or lack of it) in South Africa, Lesotho, Swaziland, Zimbabwe, Mozambique, Madagascar, Botswana, Namibia, Zaire, Tanzania, Kenya, Uganda, Rwanda, Burundi, Zambia, Malawi, Angola, Congo, Central African Republic, Gabon, Equatorial Guinea, Ethiopia, Eritrea, Djibouti, Somalia, Sudan, Chad, Libya, Tunisia, Egypt, Algeria, Morocco, Ghana, Ivory Coast, Liberia, Sierra Leone, Guinea, Senegal, Guinea-Bissau, Gambia, Mauritania, Mali, Burkina Faso, Togo, Benin, Niger, Nigeria and Cameroun

Apr 1, 1996

By L. Nahai

Iran's petroleum industry is nearly 50 years old and the oldest in the Near East. According to published figures, Iran ranks third in production and reserves in the Near East. These reserves (including probable reserves) are estimated at 35 billion barrels and constitute about 11 percent of the world's total. Iran is the sixth largest producer of crude petroleum in the world. The 1961 output of more than 430 million barrels was 5 percent of total world output for the year. In the same year, Iran ranked fourth among world petroleum exporters, providing 8.4 percent of total world exports.

Jan 1, 1963

By Travis Q. Lyday

Mineral production in Fiji, a group of 322 volcanic islands and atolls of Melanesia in the southern Pacific Ocean, continued to be dominated by gold. However, the Fijian mineral sector remained a minor factor as a source of export earnings, Government revenues, and employment, generating only 1% of the gross domestic product (GDP), estimated as $1.2 billion.2 The largest and most important mining operation was the Vatukoula gold mine on the north side of Viti Levu, the main island. The Vatukoula Mine has been in prduction since 1932, producing about 3.8 million troy ounces of gold and 1.3 million troy ounces of silver to date. In April 1983, the large Australian mining firm, Western Mining Corp. (WMC), assumed operation of the mine in a joint venture with Emperor Gold Mining Co. Ltd., which operated the mine previously. The WMC takeover of the mine management was expected to bring in additional capital and technological expertise in order to modernize operations, increasing both efficiency and output. During the year, rate of recovery was only about 75% of the gold contained in the ore and only 40% of the contained silver. Mining at the Vatukoula Mine was done using bath opencut and underground methods, with about 60% of the ore mined attributed to the underground operations.

Jan 1, 1985

By Robert W. Waytulonis

The Federal Bureau of Mines contacted 29 organizations--mine maintenance departments and equipment manufacturers--concerning service experience and construction of diesel exhaust-gas water scrubbers. Scrubbers are used primarily on mobile diesel-powered mining equipment subject to 30 CFR 36. Because the scrubbers cool exhaust gas and act as flame arresters, their failure would compromise safety in underground mines. Scrubber maintenance problems and frequency and modes of failure were identified, and construction materials and techniques were evaluated. Three failed scrubbers were randomly selected from two cooperating mines, and their modes of failure were determined. In conjunction with failure analyses, mine water and scrubber water solution samples were chemically analyzed to characterize corrosive properties. Sludge and mineral deposits and different types of corrosion and metal fatigue were identified as problems leading to scrubber failure. The corrosion process is explained; maintenance practices, construction materials, and manufacturing methods that could be used to reduce premature failures and allow longer effective scrubber life are identified; and basic changes in scrubber design are suggested. If type 304 stainless steel is used throughout the scrubber and regular maintenance is performed, long, dependable service can be expected. Other materials such as 304L, 316, or other more exotic steel alloys may be necessary under certain conditions.

Jan 1, 1982

By Wesley T. Holmes

This report describes the second phase of an investigation aimed at obtaining a wider knowledge of the problems involved in smelting titaniferous magnetites. Liquidus temperature measurements were made on selected synthetic slag compositions in the Ti02 -A1203 -FeO-Si02 -CaO-MgO system. Both the hot-stage microscope and the strip furnace (melting-holding-quenching technique) were used during test procedure to determine the effects of CaO, MgO, and SiO2 on the liquidus temperature of slags. The liquidus temperatures of slags studied ranged from 1,241° to 1,900° C. The lowest liquidus temperature for each Ti02 plus A1203 plus FeO weight-percent generally occurred when the difference between CaO plus MgO and Si02 was less than 12 weight-percent. In this investigation substitution of either CaO or MgO for SiO2 and MgO for CaO raised the liquidus temperature of more than 50 percent of the reported base slags when Ti02, A1203, and FeO contents were held constant. The results of this investigation may serve as guidelines for determining flux requirements in smelting a wide variety of titaniferous magnetite concentrates or ores.

Jan 1, 1968

By Richard J. Finno

This paper presents an overview of methods that can be used to predict damage to buildings as a result of excavation-induced ground movements and describes an adaptive management approach for predicting, monitoring, and controlling excavation-induced ground movements. Successful updating of performance predictions depends equally on reasonable numerical simulations of performance, the type of monitoring data used as observations, and the optimization techniques used to minimize the difference between predictions and observed performance. This paper summarizes each of these factors and emphasizes their inter-dependence. Case studies are presented to illustrate the capabilities of this approach. Examples are given to show how optimized parameters based upon data obtained at early stages of excavation can be used to predict performance at latter stages, and how they can be applied to other excavations in similar geologic conditions.

Jan 1, 2010

By Sean Gallagher, Gene Wilson, Christopher Mark, Craig S. Compton, Gregory M. Molinda

Falls of small pieces of rock from between roof bolts continue to cause fatalities and to injure hundreds of coal miners each year. Roof screen is the most effective way to prevent these incidents, but some mines are reluctant to use it because they believe installing screen can be awkward, expensive and time-consuming. The most common type of roof bolting machine used in mines today is the dual boom, outside-controlled roof bolter. Mines who install roof screen using these machines have developed some machine modifications and techniques to ease roof screen installation. This paper describes some successful techniques and machine modifications that are being used in productive mines to assist with roof screen installation. Since the material handling involved with roof screen installation can expose miners to an increased risk of musculoskeletal injuries, the National Institute for Occupational Safety and Health (NIOSH) ergonomists, designed machine modifications and implemented a series of tests to evaluate roof screen handling procedures for outside-controlled, dual boom roof bolting machines. Roof screen installation can also have a positive economic impact on a mine by reducing the cost of injuries, workers’ compensation, required spot or re-bolting, and clean-up of long term travel and belt entries.

By John D. Bardill

Data from extensive tests was obtained on friction-head losses of various sand slurries, composed of materials of different specific gravities and under varying transport conditions, to provide useful information for designing hydraulic transport systems. The tests were run in a pilot plant through 2-, 3-, and 4-inch lines with slurries composed of relatively pure barite and limestone solids. Available grinding and classification equipment did not permit attaining a comparable size distribution in the two materials tested, thus preventing direct correlation of friction-head loss values to physical properties or mineral composition. A total of 495 measurements were made of limestone slurries in the 2-, 3-, and 4-inch pipe test sections at flow velocities from 6 to 14 feet per second and pulp densities from 40 to 70 percent solids. A total of 640 measurements of barite slurries were made in the 3-and 4-inch pipe test sections at flow velocities between 7 and 14 f.p.s. and pulp densities ranging from 40 to 80 percent solids.

Jan 1, 1962

By J. A. L. Napier

This paper presents an overview of work carried out by the CSIR Division of Mining Technology and formerly by the Chamber of Mines Research Organization (COMRO) to quantify the behaviour of the stope fracture zone near deep level goldmine stopes. The motivation for this work is first reviewed in the context of the unsatisfactory status of current mine layout design criteria. Numerical methods to represent failure processes are reviewed briefly. Specific studies of microfracture processes are described as well as physical modelling experiments that can yield insights into deformation mechanisms. Modelling of stope scale deformation mechanisms are presented and considerations relating to elastodynamic modelling of the rock mass are described. The implications of this understanding in relation to prospects for active fracture zone ?engineering? are outlined and finally, the directions of future research work are proposed.

Jan 1, 1997

By David K. Hylbert

This study was designed to investigate roof falls in room-and-pillar drift coal mines and to determine geologic methods for predicting unstable roof conditions. The study area was located in Harlan County, Kentucky and the Bailey Creek (Harlan coal bed) and Highsplint (Darby coal bed) mines were selected for study. Correlations were made laterally between surface outcrops and within the mines using lithologic and trend analysis criteria. Lithologic criteria compared cyclic changes in roof strata. Results indicated that roof falls are associated with zones of weakness within or between five vertical cycles recognized. Abrupt lateral facies changes occur. In the Highsplint mine the roof was classified in four categories or conditions using 98 rib sections for control. Structure contour and isopach maps were used to project axial trends of the sandstone roof. A roof-fall zone was examined using ten NX cores taken from the roof and included lithologic, petrographic and clay mineral studies. At the Bailey Creek mine roof failure was caused by the heading direction being driven subparallel to paleochannel directions. Computer programs were used in trend analysis studies. Cross-bedding, paleo-channel trough axis and sole mark studies indicated a 350 discrepancy between surface and in-mine trough axes at Highsplint. A direct relationship between joint and "slip" frequency and direction with sandstone roll trends was found. Surface joints compared well with drainage Segments, hilt did not correlate with roof falls in areas of mines under overburden in excess of 600 feet.

Jan 1, 1977

By A. Moss

The Palabora Mining Company has successfully extended the life of its operation by developing a 30 000 tpd block cave underground mine below the now closed open pit. The process of transitioning from surface to underground mining has been technically, operationally and managerially challenging. This has been due to a number of factors, in particular, the development of a block cave in a very competent rock mass. The competence of the rock mass is clearly demonstrated in the open pit that preceded the block cave, one of the steepest deep open pit excavations in the world. With cave breakthrough, however, the pit was ?instantaneously? deepened by 400 m causing a major failure of the north-west wall involving close to 100 Mt of waste material.

Jan 1, 2006

By B. W. Gandrud

This is the third report published by the Bureau of Mines concerning the washability of Black Creek coal. Both of the former reports.5/6/ dealt with the Black Creek coal at the Bradford mine, Dixiana, Ala., near the northeastern extremity of the Warrior field, whereas the present report is based on float-and-sink tests of coal from what is presumably the Black Creek bed near the southern extremity of the field. Although the Yolande Coal & Coke Co., owners of the property at Yolande No. 6 slope, consider this opening to be on the Black Creek bed, the authors do not feel that there is as yet positive proof that this correlation is correct. There has been little or no development of the Black Creek bed in the Yolande Basin in the past, and a positive identification of the bed at Yolande No. 6 will have to await further exploration and development. The Yolande No. 6 is an exploration slope 3/4 mile north of Rockcastle, Ala. The slope is approximately 400 feet from top to bottom on a dip of 180. As far as the authors can ascertain, coal has never been produced commercially from the Black Creek bed in the southwestern part of the Warrior field. Exploration work in the past has indicated that the Black Creek coal in this area is extremely friable and high in sulfur. Extreme friability would naturally discourage its use as a domestic and railroad fuel, and high sulfur content would be a disasvantage in its use for coking coal. The present study of this coal has been made with particular reference to sulfur elimination on the assumption that it would make a good coking coal provided enough of the sulfur could be eliminated by washing.

Jan 1, 1939

By John J. Sammarco

The U.S. Bureau of Mines has developed a regulated, intrinsically safe, rechargeable power supply for portable electronic equipment for underground use. The regulated output is ideal for microprocessor power requirements and is suited for operation in hazardous environments. Two rechargeable, sealed batteries are contained within the power supply. Provisions are made to use an external source of power if these batteries fail. Provisions are also made to charge these internal batteries when needed. The circuit is composed of three main circuits: the main regulator circuit, the input protection circuit, and the output protection circuit. The main regulator circuit provides remote voltage sensing, current sensing, fault monitoring, and internal thermal protection. The input protection circuit checks for excessive input current and low battery conditions. The output protection circuit contains two overvoltage detection devices. Schematics, a parts list, and a calibration procedure are provided in this report to enable readers to fabricate the power supply.

Jan 1, 1989

By K. Goshtasbi

The mechanical behaviour of schistose sedimentary rocks such as slate show a great amount of anisotropy. Hence, the schistocity plane is essential when investigating the mechanical behaviour of such rocks. The presence of such rocks in civil projects causes non-symmetric deformation and their behaviour is unpredictable. In this research, the anisotropic strength behaviour of slates is studied. Uniaxial and triaxial tests were conducted on specimens having orientation angles (ß) of 0, 30, 45, 60, 75 and 90 degrees. The triaxial tests were done at confining pressures of 3, 5 and 10 MPa. The effect of anisotropy on uniaxial and triaxial strength, cohesion, angle of internal friction and Hoek and Brown's m and s constants were investigated. The results indicate that the strength of slates in uniaxial and triaxial compression exhibit a U-shaped anisotropic behaviour. In-order to evaluate the most suitable criterion for predicting the anisotropic strength of rocks in uniaxial and triaxial compression, an investigation was carried out on various criteria. In uniaxial compression, the Liao and Huong and Ramamurthy criteria had good agreements with the test results. In triaxial compression the Hoek and Brown and Mc Lamore criteria had better agreements with the test results. It should be noted that in-order to utilize these criteria, a large number of tests must be carried out. However, as the Ramamurthy criterion needs fewer test results, it can be the most suitable for investigating the behaviour of anisotropic rocks in triaxial compression. Keywords: Slate, anisotropy, schistose, failure criteria

Jan 1, 2006

By Austin E. Dwight

IT has been shown by Oelsen and Wever' that the effect of a solute element on the allotropic transformation in iron is dependent upon the quantity

Jan 1, 1957

By J. S. Stachulak, K. A. Mackinnon

This paper deals with specifying and evaluating fans for mine ventilation projects. Topics such as fan and equipment design life, operating points, and operating conditions are discussed. Common operating problems, such as vibration, parallel operation, mechanical failure, erosion, corrosion, and deficient fan performance are covered. Apart from identifying the potential operating problems, likely causes and suggested remedies are given. Fan type, fan accessories, and likely system effects and fan testing are discussed. Suggestions on what should be covered when evaluating different fan options and proposals and suggestions on the verification of supplier claims and guarantees, including cost of operation, the evaluation of initial capital cost, estimate on maintenance costs, and likely replacement expenditure over the life of the fans. In addition, fan reliability, operational flexibility, suggested construction details and fan vendor past history and experience are reviewed.

Jan 1, 2004

By F. Pagliacci

Retaining walls for the construction of underground urban infrastructures have to be executed considering the impact of a deep foundation job-site within an urban network. Traditional excavation systems, based on the use of grabs and bentonite mud, involve serious problems such as: the opening of trenches adjacent to existing buildings; the cleaning of the working area; the site installation for the production and storage of the bentonite mud; the transport and disposal of soil contaminated with bentonite mud. Alternative solutions have therefore been developed in order to overcome these problems. For temporary works soil consolidation methods, combined with the use of sheet piles, have been implemented, by a combination of traditional mixing methods and jet grouting systems to speed up the operations, consequently reducing the construction time. For permanent works two new techniques named respectively CSP (Cased Secant Piles) and CDW (Continuous Diaphragm Walls) have been studied, applied and tested.

Jan 1, 2000

This paper describes the economic study of longwall versus bord and pillar mining using all continuous miners for a colliery located at the South Coast district of New South Wales, Australia. In this district longwall mining appears to be a better economic proposition than bord and pillar. The internal rate of return on investment is found to remain approximately constant for each method irrespective of life. The economic importance of percentage extraction of coal is shown to be small for high values of minimum rates of return, becoming more significant as the minimum rate of return decreases.

Jan 1, 1980