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By Gary S. Brierley, Tracy J. Lyman

INTRODUCTION Geotechnical engineers play a major role in tunnel design primarily because tunnels are constructed entirely within the ground. In general, this role can be divided into two major tasks: subsurface investigations and project design. Under subsurface investigations, it is necessary for the geotechnical engineer to accurately describe the ground in which the project will be built. Under project design, it is necessary for the geotechnical engineer to work together with other members of the design team to make certain that the tunnel fulfills its intended purpose at least cost. Given in the paper are the authors' opinions about what constitutes an adequate scope of services for these two tasks on a tunneling project. SUBSURFACE INVESTIGATIONS o Background Study All subsurface exploration programs for tunnels begin with a thorough investigation of background information about the proposed site. Such background information includes geologic, reports topographic maps, aerial photography, and case history reports of other nearby tunnels. Once completed, it is necessary to study the background information so that the proper scope and magnitude of subsurface exploration work is performed in a manner that provides maximum input to a knowledge of those intact and rock mass properties that are important for an understanding of the entire ground mass. The blind application of field and laboratory techniques, no matter how sophisticated, is wasteful and potentially

Jan 1, 1989

By Robert G. Ditchburn

The Mariana arc is an ~1,400-km-long intraoceanic arc that marks the southern extension of the Izu-Bonin arc, and is host to 62 ?volcanic centers? of which at least 27 (21 submarine) are hydrothermally, or volcanically active. A surface ship cruise in early 2003 mapped the distribution of hydrothermal plumes emanating from these centers, followed by remotely operated vehicle (ROV) cruises with ROPOS in 2004 and Jason II in 2006. With the exception of one volcano (East Diamante), none of the vent sites visited by the ROVs were host to sulfide mineralization. Rather, they were characterized by high sulfidation mineral assemblages dominated by native sulfur. The sulfur was seen marking the vicinity of vent sites, or as sulfur ?chimneys? (e.g., NW Eifuku and Nikko), or more spectacularly as ?lakes? of molten sulfur, either occupying the summit crater of the volcano (e.g., Nikko), or perched on the flanks of the volcano, near the summit (e.g., Daikoku). Gas (H2S and CO2) was discharging through the molten sulfur. Evidence for these lakes to have either been substantially ?deeper? in their recent past (e.g., Nikko), or existing at other volcanoes (e.g., Seamount ?X?) is given by remnant ?pillars? of native sulfur that are reminiscent of rock pillars in lava lakes found along mid-ocean ridges.

Jan 1, 2008

By Vinton A. Garbesi

The construction involved in the Washington Metropolitan Area Transit Authority (WMATA), Contract No. lK0011 (K-1), encompassed some 2,621 meters of single track parallel tube rapid transit tunnels, 335 meters of cut-cover subway station and appurtenant ventilation structures at each end, and a fan shaft at approximately the mid point of the tunnels. The construction contract was awarded June 7, 1974 to a Joint Venture consisting of Intercounty Construction Corporation, Hyattsville, Maryland, and S $ M Constructors, Inc., Solon, Ohio. The former being responsible for performing the cut and cover construction, and the latter being charged with constructing the running tunnels and fan shaft at their mid point. (See Fig. 1) The problems of mining and supporting, the 183 meters of twin tunnels just east of Court House Square Station, by unique mixed face and soft ground mining methods is the main subject of this report, although a general review of the tunnels in their entirety, as well as the geology encountered in the excavations, is presented to give a better overall setting for the problems encountered. GEOLOGIC SETTING The tunnels for the K-1 contract are located in three general types of material; the first being fractured and metamorphosed ignious rock (quartz-hornblende-biotite gneiss), the transition zone between weathered and competent rock, and in ground consisting of the weathered

Jan 1, 1979

By Charles D. Litton

This report describes a smoke particle detector which utilizes a novel three electrode configuration and 5.0 [] source of Americium 241. The detector operates on the principle of diffusional charging by a region of unipolar molecular ions. The detector is sensitive to particle concentrations in the range of 10 to 5 20 ug/m3. The detector is intended for use primarily as an early warning fire detector but has the potential for other applications of particulate monitoring. In particular, this report adresses the potential use of the detector for monitoring diesel particulate matter (DPM). To assess the viability of this application, particle size data obtained from in-mine sampling of both DPM and dust were used to derive detector sensitivity functions for DPM and dust as a function of their mass concentrations only. These sensitivity functions are dependent upon the average diameters and size distributions of the DPM and dust. Using the derived sensitivity function for DPM, experiments were conducted in a ventilated tunnel where the true DPM mass concentrations, measured using a Tapered Element Oscillating Microbalance (TEOM) were compared to the mass concentrations calculated using the detector sensitivity function. The agreement between the two measurements was good, indicating that with additional experiments, coupled with in-mine evaluation of the detector, refinement of the device for use as a continuous monitor for DPM appears feasible.

Jan 1, 1989

By Robert A. Jankowski, Jonathan Kelly, Edward F. Divers

Results for the first underground test of the ventilated drum in a U.S. coal mine are presented. Tests were conducted by the Bureau of Mines through a contract research program with Foster-Miller, Inc., to evaluate dust control effectiveness in a western mine and for gas control in a full scale laboratory facility. The ventilated drum is designed to reduce the amount of dust from cutting by drawing dust-laden air from the cutting zone through twelve water- powered "dust capture" tubes built into the shell of the shearer drum. High pressure water up to 1 12.48 kg per cm2 (1,600 psig), released from sprays, induces maximum airflow of 1.89 m3/sec (4,000 cfm) from the face side of the drum and provides cleaning for respirable dust and improved methane dispersion. At the gob side of the drum a deflector plate, attached to the cowl arm, turns the water spray and a proportion of the cleaned air back into the cutting zone. More than 50 ventilated drums have been installed to date in England, and their tests carried out on fixed height and single-ended ranging drum shearers have shown reductions in respirable dust of 60-80 pct, as compared with conventional wet cutting. The U.S. test on a double drum shearer showed slightly lower reduction.

Jan 1, 1987

By H. Dr. Boldt, J. Dr. Henneke

PREFACE In German coal mines the application of tunnel boring machines has become a very effective and economic technique for major development works. After initial trials around 1970 the breakthrough was reached by driving 13 km of road ways on Rheinland and Friedrich Heinrich collieries, using a DEMAG tunnel boring machine of 6 m diameter. INTRODUCTION The coal mines of Rheinland and Friedrich Heinrich are to be found in the West of the Ruhr Area, the largest coal mining area in the Federal Republic of Germany (Table 1). They form part of the Ruhrkohle company. Rheinland coal mines produces 41000 to 43000 t of run-of-mine coal every day, of which 20500 t are usable coal. Friedrich Heinrich has a daily production of 17000 t of run-of-mine coal, 9000 t of which are usable. The coal is worked at depths of 600 to 1100 m in seams 0.6 to 3.0 m thick. The method of mining is longwall, and the machines used are ploughs and shearer loaders. From 1973 to 1980 a programme was put into operation in these two mines to develop and open up the coal field on the 885 m level. A total tunnel length of 20 km was to be driven. After thorough investigations it was decided to employ a full-face tunnel boring machine for

Jan 1, 1981

By Walter E. Heinrichs

This case history really started during the tail end of WWII when two Navy men, both Colorado School of Mines graduates, got together in Washington, DC, while they were assigned to the Office of Navy Petroleum Reserves doing some of the first aerial magnetometer work ever done on a practical oil exploration basis over the offshore area of the Gulf Coast. When separated from Naval Service active duty in 1946, the two men, Walter E. Heinrichs, Jr., and Robert E. Thurmond, tried, unsuccessfully, to form a commercial air magnetometer business. Later they got together again in Jerome, AZ, with Newmont Mining's early geophysical exploration endeavors from 1947 to 1949. Subsequent to the Newmont experience, they jointly proposed a specific mining geophysical exploration and development program to Herbert Hoover, Jr., then president of United Geophysical Co. of Pasadena, CA. Mr. Hoover, in consultation with his father Herbert Hoover and others of his staff at United, particularly Edwin G. Schempf, executive vice president, and Raymond A. Peterson, vice president of research, agreed to establish the proposed program under United's auspices, to be headquartered at Tucson, AZ. The primary objective would be to practically test and develop various mining geophysical methods and techniques while exploring particularly for base metals in the general area of southeast Arizona and southwest New Mexico.

Jan 1, 1991

By Brock H. Morrison

One of the major criterion of any mechanised tunnelling operation is to minimize downtime of the tunnelling machine by employing the most efficient muck handling system space and economic factors permit. A tunnelling machine which remains idle during a large percentage of the available shift working time is a luxury no contractor can afford. There are several possible reasons for non-productivity of a tunnelling machine ... the inability of the muck handling system to keep pace with the tunnelling machine on a continuous basis is one major cause. In large diameter tunnels, where several trains or more than one muck hauling unit can operate simultaneously, downtime of the tunnelling machine may be kept to an acceptable level. On small to medium diameter tunnels, 8 feet to 14 feet in diameter, the muck removal support system is normally restricted in capacity, resulting in an excessive tunnelling machine downtime as the tunnel extends from the shaft. There is a need for an efficient, continuous and economical muck removal system for small to medium size tunnels being driven by a hard rock machine. This paper is intended to provide an insite into pneumatic conveying, and explain the Radmark System; its development and utilisation in the tunnelling and mining fields. STATE OF THE ART Pneumatic conveying is the transportation of bulk materials

Jan 1, 1997

By David M. Sullivan

Jim Walter Resources, Inc., (JWR) a division of Jim Walter Corporation, has 5 underground coal mines in Central Alabama varying in depths from 400-2500 feet. Gas Chromatography plays a vital role in safety and production at each mine. Chromatographic data is used to monitor working areas for safety and proper ventilation and to control the quality of extracted methane for sales purposes. Instruments have a1 so been employed during mine rescue operations. JWR's first Gas Chromatograph (GC) was installed in April 1984 to monitor gob gas taken from longwall gob areas and sold based upon BTU value. The GC allows maximum extraction rate of the gas within the quality guidelines. By late 1985, another system was purchased and both units were upgraded to perform an analysis of indicator gases which may appear during mine emergencies. Each unit has the ability to detect and measure the following gases at almost any level ; Oxygen (021, Nitrogen (N2), Methane (CH4), Carbon Dioxide (C02), Hydrogen (HZ), Carbon Monoxide (CO) , Ethylene (C2H4), Ethane (C2H61, Acetylene (C2H2) and a composite of hydrocarbon threes and above (C3+). The analytical run is accomplished in less than ten minutes and is completely automated. This report will introduce Gas Chromatography as applied by Jim Walter Resources for the analysis of underground mine air.

Jan 1, 1987

By Michel Grenier, Gopal Kunchur, Stephen Hardcastle

This paper presents the findings of a dust study in a typical fluorspar processing plant. The primary purpose of this study was to identify employees and occupational groups exposed to high dust levels and determine compliance with personnel regulations for regular and extended work shifts. The range of airborne concentration of respirable silica and fluoride compounds in specific areas and on personnel was determined. State of the art dust monitoring equipment and tracer gas techniques were used to measure dust concentration, pinpoint dust sources and map major airflow trends in the mill. Results of the survey indicated silica dust concentrations in excess of permissible limits being produced mainly by crushers at the south end of the building. Tracer gas releases and gas chromatographic analysis further showed that prevailing south to north air currents tended to carry and spread dust produced by the crushing operations throughout the process plant. Airborne concentrations of fluoride compounds measured during the study were always well below the prescribed threshold limit value (TLV) for the contaminant. Recommendations, including a mechanical exhaust ventilation system on crushers and transfer points, scheduled preventive maintenance on existing bar sprays and wearing of personal protective equipment were made which significantly improved the work environment. Further testing conducted after Installation of the dust extraction system revealed significant improvements in most areas of the mill.

Jan 1, 1991

By Nancy J. Wheatley

I. INTRODUCTION The Massachusetts Water Resources Authority (MWRA) is a regional water and sewerage authority which provides wholesale water and sewer services to the Metropolitan Boston area. The MWRA was created by the Massachusetts Legislature as an independent authority in 1985 following the filing of a lawsuit in federal court to correct the pollution of Boston Harbor resulting from inadequate and inadequately maintained sewerage facilities. Immediately upon its creation, the MWRA began to tackle treatment plant issues, including addressing the need for a secondary treatment plant, planning for ceasing ocean discharging of sludge, and making interim repairs to the existing, antiquated treatment plants. The MWRA's initial activities led to a court-ordered schedule for construction of a single new primary and secondary treatment facility, for development of sludge management plan focussed principally on reuse, and for completion of a short term program of repairs to existing facilities. Once a schedule for completing these activities had been negotiated, the U.S. Environmental Protection Agency (EPA), a plaintiff in the federal court case, asked that the MWRA take "responsibility" for controlling discharges from combined sewer overflows (CSOs) within its service area. Combined sewers (sewers in which both sanitary sewage and storm water runoff are carried in a single pipe) presently discharge over 10 billion gallons of untreated wastewater into Boston Harbor and its [ ]

Jan 1, 1991

By Charles N. Speltz

The cost of transportation of industrial minerals frequently is higher than the cost of the product. When a mine, industrial-mineral plant, or customer is served by a single railroad, because of the lack of competition, that railroad may in- crease rates and/or reduce service so that the economics of that mine, plant, or customer are affected adversely. Transloading of industrial minerals from rail-to-truck or truck-to-rail to improve economics and sales of product is not a new concept. However, transloading to create competition and reduce freight costs or to improve service is a relatively new concept brought on by the recent mergers of many of the main-line railroads, both in the eastern and western United States. For example, in 1998, with completion of the Burlington Northern/Santa Fe (BNSF) and the Union Pacific/Southern Pacific mergers (UPSP), the western United States has only two main-line railroads. The industrial-mineral producer, to reduce the cost of transportation or increase the level of service, must evaluate potential transloading opportunities in light of higher prices and reduced service brought on by reduced railroad competition. This paper discusses industrial-mineral transloading and examines the case history of the Tucker Hill perlite project in southern Oregon. The Tucker Hill project is a classic study of industrial-minerals transloading where the project would have failed without the transloading.

Jan 1, 1999

By James S. Goff, Stephen J. Navin, Wesley W. Moulton

The White River Shale Oil Corporation (WRSOC) is developing a prototype oil shale facility on Federal Lease Tracts Ua and Ub located in northeastern Utah. This paper covers the successful driving of 1,525 m (5,000 ft) of dogleg downgrade decline with a 70-ton Paurat Roadheader mining machine and a conveyor muck-handling system. Ground support is with rock bolt and shotcrete; welded wire mesh is optional. The Upper Decline of 3.89 m by 8.69 m (12.75 ft by 28.5 ft) was mined through the Uinta Formation sandstones and shales in 210 days. The sandstones have a compressive strength in the 48 MPa (7,000 psi) range with a few bands of shale up to 137.8 MPa (20,000 psi). Green River Formation dolomitic marlstone with some sandstone lenses was mined in the Lower Decline 3.89 m by 5.64 m (12.75 ft by 18.5 ft) in 175 days. The Green River marlstones are tough massive formations ranging up to 206.8 MPa (30,000 psi). Roadheaders for use on steep slopes must be modified to accommodate the particular problems associated with mining downdip. The paper concentrates on the application of Roadheaders to steep slopes and the problems of mining tough materials such as marlstone. The paper also shows the advantage of using the method of excavation on long drives.

Jan 1, 1985

By D. U. Deere, T. R. Harrell

Factors such as rock cover, rock type and rock quality can exert a dominate influence on the behavior of a concrete tunnel lining. This paper will present and discuss the investigation, evaluation and use of such factors at the Rocky Mountain Pumped Storage Project in the design of the 10.67m (35 foot) diameter concrete tunnel lining. A plane strain, finite element analysis was performed on the concrete/rock system. The finite element model consisted of a concrete lining zone and three (3) rock zones; a highly destressed rock zone, a transitional rock zone and an intact rock zone. Zones were differentiated from one another by varying the modulus for each zone. Results of this study yielded a concrete lining strain from radial expansion which was used in the crack control calculations for the concrete tunnel lining. After the tunnel excavation was performed, plate jacking tests and additional seismic surveys were run on the tunnel walls. This testing served to confirm the rock modulus values used in the preliminary analysis. However, results were observed which indicated that a two zone rock model would more accurately represent in-situ rock conditions than the three-zone rock model used in the preliminary analysis. This revision to the concrete/rock model was made and a final concrete tunnel lining analysis was performed.

Jan 1, 1986

By Mortimer J. Richardson

In the context of this session on "Practical Placer Mining," a projection of the present into the future first assumes that there is a future for Placers. The second assumption is that there is the combination of adequate reserves and a willing, mining investment source to finance placers. This paper will point out the opportunities on both assumptions, illustrating my positive position on the future of gold placers. In order to focus this paper more effectively, I have chosen GOLD as the subject mineral. However, it is recognized that much of the technology for exploring and mining gold placers has been applied to other alluvial deposits; including platinum, diamond, tin, and various industrial minerals (which are often referred to as "placers" though this contradicts historical definitions). Over the past 10 years I have presented several papers on the general subject of placers, most of which are listed under References. These have included topics such as exploration, evaluation, small-scale gold placer mining and decision-making, mining and processing equipment designs, and dredge-mining operations. In an attempt to identify the more promising, undeveloped placer potentials in the world I have usually mentioned the USSR and China but qualified them as being either inaccessible, or, politically difficult to obtain. However, with recent developments in the USSR, the obstacles appear to be somewhat diminished.

Jan 1, 1992

By John J. Reed

The 1945 fire at the Braden (El Teniente) Copper Mine in Chile took 354 lives, and ranks as the most lethal metal mine fire in history. The mine was developed in the wall of a canyon over 900 m (3,000 ft) deep. Principal entrance was through a main haulage adit at the canyon bottom, and up through two internal shafts. Mining was by block caving from the top of the orebody with most of about 900 men on shift working in three production areas. Ore was transferred by gravity to the haulage level through a complex system of ore passes with associated ladderways. Normal mine ventilation was incast through numerous level portals and up- cast through the shafts and raises. The fire was confined to a maintenance shop just inside the portal of the lower production level. Smoke, gases and flammable vapors were drawn into the mine, and a subsequent explosion of the gases destroyed an air door and injected carbon monoxide into the workings. Falling water in a drainage raise near the fire made it downcast, which carried gases down to all the lower levels where they were drawn into the levels and then up connecting raises. Miners attempting to escape by climbing down the ladderways from the production levels were met and killed by the rising gases.

Jan 1, 1989

By James Sheridan

Risk can generally be defined as the possibility or chance of a loss corresponding to uncertainty. Analysis is the process for examining the components and relationships of a complex system in order to determine the impacts of its variables. Risk analysis is therefore a course of action taken to analyze multiple variables of a system that is subject to speculative outcome. When risk analysis is applied to mine development, it becomes the means for assessing and measuring those parameters that contribute to economic viability. Mining can be a risky business. It is composed of an assortment of factors that contribute to its financial outcome. Of these factors, the most consequential output is the net present value (NPV). Applying risk analysis in mine development can identify those factors having the most significant impacts and applying limits to those impacts. Mathematical computer modeling using Monte Carlo techniques is available and can be customized to suit specific mine development ventures. Essentially, those parameters that are not fixed values can have input variability. Rationally deduced engineering estimates should be the basis for determining the initial values applied as inputs in the models. Risk analysis therefore provides the user a means to identify, rationalize and assess the risks in mine development in an informed, calculated, and unbiased format for making economic decisions.

Jan 1, 2002

By G. S. Grainger, R. A. Cummings, F. S. Kendorski, R. L. Butts

Georgia Power Company's Rocky Mountain Project, located approximately ten miles northwest of Rome, Georgia, in the Valley and Ridge Physiographic Province, is a pumped-storage facility rated at approximately 800 megawatts of peaking energy. Geological field explorations and borings enabled the division of the rocks along the tunnel and shaft alignment into distinct lithologic units and defined the ground--water regime. Field explorations included a detailed analysis of the rock mass discontinuities at available rock unit exposures. Testing of rock strengths was performed in several phases in both the field and the laboratory. The field testing consisted of point-load testing, geophysical testing, in situ load testing, and hydro-fracture testing. Laboratory testing determined the Brazilian split-tensile strength, the unconfined compressive strength, the triaxial compressive strength, the joint-direct shear strength, and the pulse velocity. The rock mass along the tunnel and shaft was also characterized by empirical classification systems. The classification systems included the Rock Mass Rating (B1IR) and the Rock Mass Strength Determination (RHSD). The results of the field explorations, field testing, laboratory testing, and rock classifications were used to divide the rocks into two structural groups. These rock groups were defined as volumes of rock wherein the rock mass behaves similarly in response to the excavation. Each group, therefore, required separate rock engineering consideration.

Jan 1, 1986

In 1991, most industrialized countries, except for Germany, were in a recession or a period of reduced growth. The US economy, already in recession, suffered from mounting banking system losses and the uncertainty brought about by the Persian Gulf War. However, US and worldwide minerals exploration did not collapse as it did during the mid-1980s. Even though gold and base metal prices declined, prices were still above cash costs for most operations. This allowed the continuation of established exploration programs but sharply limited new initiatives. Exploration 1990-1991 Planned worldwide 1991 exploration expenditures declined by about 8% from 1990 levels, according to a survey of 153 companies by the Metals Economic Group (MEG). Canada was the leading exploration target with 23% of the total, followed by Australia and the US (19% each), South Africa (13%), Latin America (11%) and the South Pacific (7%). The remaining 8% was split evenly between Europe and the rest of Africa. In Latin America, Mexico and Chile are the most attractive countries for exploration. Recognizing the risks involved, the industry has been cautious about ventures in the former Soviet Union. Survey results also showed that while the majors expected to maintain exploration spending, smaller firms were cutting back or actively seeking farm-outs from the majors (personal communication, M. Wegener, MEG).

Jan 1, 1992

By David Conover

The El Boleo Copper Project is currently in the final design stages for development of a 3-MM-tonne/yr underground copper mine located in Baja California, Mexico. The nearly horizontal mineralized zones are amenable to exploitation by conventional mechanized coal mining technology using continuous miners, shuttle cars, and belt haulage. The mine design resembles a typical full-extraction coal mining operation utilizing a sequence of mains, sub-mains and production panels. Due to numerous faults, mining will be conducted as several small adjacent mines accessed through adits from large arroyos cutting through the mine area. Up to four seams may be mined in some areas with a maximum overburden depth of about 250 m. The ore zone is relatively weak and plastic, subject to extensive creep over time. The mine workings will pass through areas of historical shortwall mining panels where the ground has flowed into old entries and gob areas, and then reconsolidated. A small test mine was developed to evaluate mechanical cutting performance, roof-bolt anchorage capacities, roof and pillar stability and caving behavior. In-mine measurements were combined with two- and three-dimensional FLAC models to evaluate alternative development and production pillar designs. The paper will discuss the various factors influencing ground stability at the El Boleo project and the strategies employed in developing a suitable ground control design.

Jan 1, 2009