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By Dr. Peter J. Conroy

The current study is part of the U.S. Department of Energy's (DOE) on-going subsidence research program. The long-term objective of the DOE program is to develop analytical methods of subsidence prediction applicable over a broad range of geologic and mining conditions encountered in the United States. The DOE currently has several contracts in progress to develop a sound data base that can be used in the development of predictive models. Dames & Moore is currently under contract to the DOE to collect and analyze detailed subsidence and hydrologic data from a coal mine employing longwall mining methods in the Eastern Coal Province. Work under Contract No. DE-AC22-80PC 30335 began in October of 1980 and will continue through September of 1984. This paper summarizes the work that has been completed through September of 1981 and presents the results that have been achieved during this period. Technical difficulties encountered during both the installation and monitoring phases are discussed, and recommendations for future work are presented.

Jan 1, 1982

By D. Bogh

Wound rotor motors are used in difficult mining applications where there is a need to start high inertia, hard starting loads while limiting inrush current They are recognized as robust and simple to control. This paper will cover the performance, specification, and important issues to be considered when applying medium voltage wound rotor motors in mining applications. Medium voltage grinding, crusher, and conveyor applications will be discussed. Specifically covered are motor efficiency, speed range, and rotor control. Crane motors often have wound rotor construction, but their load cycle and ratings are outside the scope of this paper.

Jan 1, 2011

By Chris Bennett, Drupad Desai, Kirit Mevawala

INTRODUCTION The design/build (D/B) philosophy of contract delivery is neither new nor unusual when it comes to at-grade, elevated or high-rise structures. But when it comes to constructing underground facilities, there were no examples to be followed in early 90sin the continental United States or its territories. When DMJM+HARRIS was selected as general architectural and engineering consultant for the Tren Urbano (TU) project in Puerto Rico, one of the requirements of the Federal Transit Administration (FTA) for funding commitment was to use TU as a demonstration project utilizing design/build contract delivery method. Now fifteen years later, New York City Transit (NYCT) has instituted a similar requirement for their first Tunnel Boring Machine (TBM) contract for the Second Avenue Subway. As with most construction mega-projects, lots of things have happened and there were several lessons learned from the TU experience that are now being applied to Second Avenue. Both of these projects require building tunnels and underground transit facilities in heavily traveled corridors of an urban city, in the vicinity of active business and commercial enterprises. To enhance the challenge, there are noise and vibration sensitive and historic urban receptors either over or along both the transit corridors. Column free Tren Urbano station caverns over18 m (60 ft.) wide were built in soft ground conditions within 3.6 m (12 ft.) of the surface under an aging heavy utility corridor, while NYCT tunnels with station structures stretching the limits of rock caverns to 34.8 m (100 ft.), were planned in rocky geology with the presence of shear and fault zones and some mixed face conditions. BACKGROUND During the early period of design/build experimentation, the speed with which the contract procurement packages could be put together enabled the owners to take advantage of the major efforts underway to rebuild the infrastructure that was suffering from post-World War II neglect. Use of design/build for new starts was unheard of and most of the projects were smaller in nature in order to allow the methodology to be tested. Development of functional design packages with the understanding that the D/B

Jan 1, 2005

By Christian Wawrzyniak

An analysis method for modeling compensation grouting based on the finite element method is presented. By this method the design parameters of compensation grouting, grouting pressure and grouting volume, can be evaluated. Also the subsidence of a building due to tunnel driving as well as the lifting of the building by compensation grouting can be simulated. The stress changes in the tunnel lining and in the foundation of the building are computed as well. The application of the analysis method is demonstrated on two examples for compensation grouting in combination with construction of tunnels.

By L. J. Prosser, A. T. Iannacchione

Unfortunately from 1991 through 1995, 44 miners were fatally injured in the stone industry. Of these 12 occurred at underground mines from a total work force of less than 2,000 miners. Nine of these 12 miners were fatally injured in falls of roof or rib. A safer environment for the miners can be achieved by evaluating the nature of the hazardous ground and by developing more efficient and effective ground control strategies. Roof and rib conditions in the underground stone industry were observed and assessed at 33 mines in Illinois, Indiana, Kentucky, Maryland, Missouri, Pennsylvania, and West Virginia [(Figure 1)]. Hazard assessment indicated that those ground failures occurring under moderate to substantial overburden (> 30 m [l00 ft]) were caused by stress concentrations and geologic structures. Ground failures near the surface are caused by solution (water) processes. Selection of the mining horizon and mine layout decisions tremendously influence ground stability.

Feb 24, 1997

By N. Ward

The Gualcamayo Mine is located in the Andes Mountains north of San Juan, Argentina (Figure 1). A property of Yamana Gold Inc, it declared commercial production in July 2009 and has a total mineral reserve and resource base of approximately 88,000 kg of gold. Crushing operations for the open-pit mine are located in a 13,500 m3 underground cavern with a ceiling height of 22 m. More than 3,600 m of tunnels are used to access the cavern and convey the ore. The Project as described in this paper relates to the design and construction of the Main Cavern, Conveyor System Exit Tunnel, the Mechanical System Access Tunnels, and two 4.20 m diameter shafts (Ore Pass #1 and Ore Pass #2) as shown in Figure 2. [ ] Preliminary engineering for the Project was performed by Hatch Chile. Rizzo Associates Argentina, S.A., a division of Paul C. Rizzo Associates, Inc (Rizzo) was contracted to provide geomechanical and geotechnical support for the construction of the access tunnel system and geomechanical design and construction supervision for the cavern and shafts.

Jan 1, 2011

By B. J. Schat, A. W. O. Bots, O. S. Langhorst

Amsterdam City Council is building a new metro line, the North–South Line. The line passes under Amsterdam Central Station (a listed building) about 18m below street level. The retaining wall that has to be built underneath the existing building is an innovative construction consisting of two rows of steel piles interspersed with a solid mass of overlapping jet grout columns: a composite ‘sandwich’ wall. This paper gives an overview of the approach taken to designing (computational models) and building the retaining wall. Special attention is paid to the observational method used for the construction of the jet grout columns.

Jan 1, 2007

By G. Bee, Z. Gavelan, R. Espinel, Y. Roditis, X. Ochoa

In August 1996 Barrick Gold Corporation acquired the Pierina property, an advanced stage exploration project, high in the Andean Cordillera of Peru and in November 1998, in a record time of just over two years, poured the first gold. After more than three years of a very successful operation at some of the lowest operating costs in the world, this presentation serves to briefly describe the project through design, construction and start-up and in particular to spotlight some of the challenges that have been overcome in valley heap leaching in a high rainfall, alpine setting.

Jan 1, 2002

By A. Adu-Acheampong

Stope instability at Ashanti Goldfields Company Ltd. (AGC) is a major concern. Using information from field mapping, major discontinuity sets were defined, Rock Quality Designation (RQD) was determined. The stability of wedges in the stope walls was assessed using the commercially available computer program UNWEDGE(Rock Science, 1992). Analytical results indicate that the presence of graphite infilling in joints contributes to instability, while steeply dipping joints control wedge slabbing and wedge toppling in the hanging wall. Stable stope widths and dimensions were determined to range from8.1 to 30 meters (m).

Jan 1, 2003

By S. Möllerherm, E. Drüppel

"The development of indicators to assess the sustainability of mineral raw materials operations is amajor task with respect to its actuality and difficulty. This holds true even more when dealing withenvironmental indicators.The use of existing environmental indicators in the mineral raw materials industry leads to false orat least distorted results. Therefore the Institute of Mining Engineering I from the RWTH AachenUniversity developed indicators and an assessment system for the mineral raw materials industryon operation, company and sector level on behalf of the Federal Ministry of Economics and Labour(Bundesministerium für Wirtschaft und Arbeit, BMWA) and the Federal Institute for Geosciencesand Natural Resources (Bundesanstalt für Geowissenschaften und Rohstoffe, BGR).In total 30 indicators were defined and designed to assess the performance of the mineral rawmaterials industry in terms of sustainable development, 10 indicators for each pillar (economical,ecological and social pillar).The following paper describes some of the results focussing on the development of environmentalindicators. These had to be adapted or completely new designed in order to match the specificcharacteristics of the mineral raw materials industry."

Jan 1, 2005

When defining a ?megaproject,? one need only to look at Seattle, WA?s State Route 99 Alaskan Way Viaduct replacement project. This $3.1-billion project is one of the largest of its kind in the world, and includes the use of the world?s largest tunnel boring machine (TBM). However, for as large as the Alaskan Way project is ? especially given the size of the TBM being used ? there are several other megaprojects underway around the world. Each has its own challenges that require innovative design techniques and financing arrangements, as well as variations on established tunneling technologies. So it was that 266 tunneling and underground construction professionals ? owners, contractors and engineers ? convened in Seattle in November for the Cutting Edge Conference on Megaprojects. This was the second joint meeting between the Underground Construction Association of SME and the North American Tunneling Journal. The first joint conference took place in April 2012 in Miami, FL and attracted 238 attendees. A third joint conference, to be held in 2014, is in the planning stage. The key reason Seattle was chosen as the site of the megaprojects conference is the Alaskan Way Viaduct project. Before the conference began, many of the attendees were able to visit the project and get a close look at Bertha, the Hitachi Zosen earth pressure balance TBM that is boring the tunnel. In addition, the conference included an exhibit that attracted 20 industry suppliers, up from 10 the previous year in Miami. The 25 presentations during the two-day conference covered all aspects of the tunneling and underground construction of megaprojects. Topics included the Alaskan Way Viaduct project; considerations for procurement and contracting; political risk, financing and insurance; international megaprojects; risk and risk sharing and project delivery. Each session concluded with panel discussions.

Dec 1, 2013

By Brian Fulcher

The Arrowhead Tunnels Project represents the final portion of a 70 km (44-mile) long water conveyance facility that will bring up to 28 m3/sec (1,000 ft 3/sec) of water into Southern California. The 13 km (8-mile) tunnelling project is well underway and consists of two, 5.8 m (19-ft) diameter TBM bores through extremely variable geological conditions. An extensive and essential pre-excavation drilling and grouting program was performed in all reaches of the Arrowhead Tunnels Project, located north of San Bernardino, CA. This program supported the advance of two hybrid hard rock TBMs though extremely challenging ground conditions under substantial ground cover and up to 27 bar (900 ft) of ground water pressure. The well known San Andreas Fault lies nearby and has greatly influenced the local geological conditions. This paper will describe the means, methods and materials used throughout the numerous phases of the pre-excavation grouting program. It will also describe many versatile, flexible and innovative drilling and grouting methods and equipment systems utilized to improve performance, save time and costs in constantly changing geological conditions. Considerable lessons learned have been learned while overcoming some extremely formidable ground conditions and safely advancing the tunnels.

Jan 1, 2008

By Christopher M. St. John, Tony F. Zahrah

Empirical and numerical methods are the two extremes of the tools available for the seismic design of subsurface excavations and underground structures. Both have their limitations: when relying on purely empirical methods directly relevant experience may be scant; site data may be insufficient to justify a comprehensive dynamic analysis. The primary purpose of this paper is to review the analytical tools available to the design engineer of subsurface excavations and underground structures. Particular attention is devoted to simplifed models that appear to be applicable in many practical cases.

Jan 1, 1985

By J. Sandford, S. Hennings

EXECUTIVE SUMMARY An approach borrowed from the petroleum industry was applied to the gas development evaluation for the Bulga underground coal mine in New South Wales, Australia. The results enabled the coal mine operator, Xstrata Coal, to systematically plan the extraction of gas in harmony with mine production planning of multiple coal seams. This has allowed for a more proactive approach in preparing the resources and infrastructure needed to capture the gas and accelerate coal mining while maintaining their high level of commitment to safety. Norwest has for decades used gas recovery simulation models to assist the petroleum industry and the coal bed methane (CBM) industry in understanding and forecasting fluid saturations and flow behavior. Norwest developed a similar process with Xstrata to migrate existing mine data at Bulga into reservoir simulation models to study various drainage alternatives. An interesting feature to the evaluation was also developing an understanding of test procedures and nomenclature from the mining industry to properly translate the data for input in simulators developed for the petroleum and CBM industries. The model was then calibrated to actual field data collected from drainage pilot tests that Norwest helped design and monitor at Bulga. The resulting calibrated predictions were then used to develop budgets, schedules, resource requirements, and alternatives for capturing the gas and delivering it to market ahead of mining. Increasing revenue, reducing emissions, improving schedules and cutting costs for the mining operations have all contributed to justifying this advanced approach at Bulga. It has also allowed Xstrata to expand their focus to the sizable gas reserves in seams not currently planned for mining. Several of these seams would be economic gas development targets once the gas recovery infrastructure is installed for the mine. The evaluation process was refined throughout this project and the resulting approach will benefit Xstrata with their broader strategic development of resources in the Hunter Valley and beyond to their worldwide operations.

Jan 1, 2007

By K. Short

Over the past several years, the mining and minerals market was overloaded with discussions around reviving mature terminologies like distributed control systems (DCS), programmable logic controllers (PLC), and the ?new comers?: hybrid control systems (HCS) and programmable automation controllers (PAC) and, in parallel, which technologies would be more appropriate for mining and mineral processing applications. Ten years ago, a careful comparative analysis would make more sense. Control approaches had very distinctive differences where users needed to choose the right approach.

Jan 1, 2012

By Robin J. Batterham

We still need to innovate, but it is getting harder. The real price of metals is declining, return on shareholder value is lower than other industries, and there is a shorter-term focus on staying viable in a capital-intensive industry where timeframes for implementation of new technologies can be long (+I5 years). In this environment, the levels of R&D spent by major minerals companies are remaining steady at around 0.2%-0.5% of revenue. This is not large and to remain viable in the future, we need to be smarter about the way in which we do R&D. The mining industry is a knowledge-based industry. Driving down the cost curve demands innovation, which demands knowledge. To be smarter and more effective in our approach to innovation, a new paradigm is required Generating, capturing and using knowledge has evolved from Mode 1 (discipline based and clear distinction between basic and applied research) to Mode 2 (multidisciplinary, team-based approached with flow between basic and applied activities). Mode 2 is now seen to be much more efficient and to deliver better appropriability (Tegart 2003). To survive, we need to innovate, and the best way to do this is collaboratively. Some examples and pointers for the future will be given in this paper. THE CURRENT SITUATION The Rand report and other recent studies have painted a grim outlook for the mining industry. The real price of metals continues to decline (Figure 1) and profit margins remain thin. This is reflected in shareholder returnwhich are well below other industries (Figure 2)-and current management strategies-which reflect something of a "survival mode." The current focus for most mining companies is on short-term, incremental gains

Jan 1, 2004

ME?s Arizona Conference was held at the Hilton El Conquistador resort in Tucson on Dec. 2 and 3, 2007. The annual conference is organized by the Arizona Conference Board of Directors, which represents SME sections in Arizona and adjacent areas. The conference provides an opportunity for individuals and corporations associated with mining in the region to get together once each year to discuss the status of the industry. The 2007 meeting featured a keynote address, a distinguished lecturer and more than 25 technical papers that were presented in seven sessions. The sessions included environmental, geology, safety, metallurgy, mining, new projects and a special session on Mexico. Topics covered included mine closure, sustainable mining, exploration methods, health and safety issues, mining equipment and drilling. Much of the discussion at the conference concerned major new developments in the region?s copper mining industry. For example, Freeport-McMoRan?s new Safford Mine and BHP Billiton?s Pinto Valley restart were the topics of technical presentations. There was also much discussion among the attendees on the current and future price of copper, community relations, education issues and recruitment concerns. At the time of the conference, the price of copper hovered around $3.30/lb, up considerably from the 61 cents/lb in late 2001, when the industry was being challenged by world market conditions and a weakened domestic economy. Since then, strong demand from China helped push copper prices to record levels that at one time reached as high as $4/lb. The general consensus among the attendees is that the current price of around $3.30/lb will continue through 2008. Most attendees also expect increased corporate investments in the industry to continue. Copper mining in Arizona has been a major industry since the 1800s. In 2007, Arizona was the leading copper-producing state in the United States and produced more than $5 billion worth of copper. The copper mining industry in Arizona also produces byproduct gold, silver and molybdenum. Arizona is the second largest molybdenum producer in the United States.

Jan 1, 2008

By Derek. C. Arnold

In order to meet increasing demands for water supply in the next millennium, the Government of the Hong Kong Special Administrative Region have identified the need for a major new water treatment and transfer scheme. The project now under construction will comprise a 1.2 km long raw water aqueduct, a major new 0.25million cubic metres per day water treatment works (with space for upgrading to 1.2Mm³/d), a 12.1 km long treated water aqueduct and a primary service reservoir. In order to meet increasing demands for water supply in the next millennium, the Government of the Hong Kong Special Administrative Region have identified the need for a major new water treatment and transfer scheme. The project now under construction will comprise a 1.2 km long raw water aqueduct, a major new 0.25million cubic metres per day water treatment works (with space for upgrading to 1.2Mm³/d), a 12.1 km long treated water aqueduct and a primary service reservoir.

Jan 1, 1999

By Roshan B. Bhappu

Integrating a research and development department into an engineering company's corporate structure can be rewarding to the engineering division, the R&D group, and, most of all, the company's clients. Actually, the R&D department is a logical extension of the conventional processing group within an engineering organization-but the R&D group provides services as needed to the engineering department while it is carrying out regular testing, pilot plant, and preliminary feasibility studies. Backup Services Provided With an R&D group, the engineering division does not need a process engineering group as such. The R&D group provides project backup services for feasibility studies, preliminary and detailed engineering, construction, and startup. The R&D group, in turn, benefits from its close association with project engineers, draftsmen, estimators, and computer capabilities in the engineering division. The client also benefits from the arrangement because R&D and engineering skills are available to both departments on an as-needed basis without standby eost. To handle the integrated responsibility of R&D projects, as well as conceptual design and preliminary feasibility studies, the R&D staff must be carefully selected. These research engineers should: • have a good background in plant practice as a mill superintendent or chief metallurgist; • be capable of organizing and supervising a testing program or a pilot plant campaign; •be innovative and willing to accept new ideas and concepts; • be able to translate lab test results into a workable flowsheet through sound conceptual design and feasibility studies; and •be able to communicate with clients. In short, the R&D engineer must be a jack of all process-engineering trades to successfully take a project from concept to operating reality. Engineers in a metallurgical R&D organization should have experience in mining and processing all types of

Jan 10, 1980

Attractive geology does not guarantee mining investment if a region’s policies are bad, according to mining executives surveyed in the Fraser Institute’s seventh Annual Survey of Mining Companies. Companies responsible for a combined US$642.4 million in international exploration (during 2002) rated the policy attractiveness and mineral attractiveness of mining jurisdictions around the world. Jurisdictions like Chile, Australia, Quebec and Nevada bolster their attractive geology with mining-friendly policies, the report said. These locations do well on the overall investment attractiveness index. On the other hand, jurisdictions like British Columbia and Indonesia, each with excellent geology, are hurt by their policies, which have lowered their score.

Jan 1, 2004