Search Documents

By Walter B. Hester

All persons and communities that have experienced strong-motion earthquakes are convinced of the importance and complexity of earthquake problems thatmust be solved in order to reduce the personal hazards and property losses to a reasonable minimum. It is also clear that absolute elimination of all risks is impossible. Reduction of existing hazards and precautionary measures which will minimize chances for disaster can be accomplished by realistic appraisal of the effects of recent earth- quakes on modern structures and installations. Localities that have reason to expect so-called strong- motion earthquakes can anticipate these effects by taking appropriate steps. Valid earthquake information can only be obtained from earthquakes. Each earthquake contributes to the body of knowledge by additional facts and by clarification of previous observations. Rational interpretation of the data followed by practical application of the conclusions can contribute greatly to the safety of persons and property. The general public expects the architectural and engineering profession to accept this obligation and render this service. Most earthquake hazards are man-made and arise from the imperfections of the works of man and his failure to anticipate the consequences when the natural characteristics of his environment are ignored. If it is not given to man to prevent such natural phenomena as earthquakes, it is sometimes within his power to control their destructive effects and to reduce to a minimum the toll of life and human suffering.

Jan 1, 1958

The global tunneling industry has many challenges, both technically and financially, with the latter likely to be a significant feature over the next few years. Many industries have ad-opted standard practices in order to overcome specific technical challenges, from which standard out-comes are anticipated. In tunneling, however, every project is unique so standardized practice is not easy. This requires original thinking and being open to adopting new techniques and technologies as they emerge. Sprayed waterproofing is a hot industry topic and a paper recently presented at the North American Tunneling conference not only discussed this methodology for achieving a dry tunnel but also how it can reduce build costs and construction time. Despite their being relatively few ?universal truths? throughout the tunneling industry, there is one opinion that appears to be shared by most in the sector, ?all tunnels leak.?

Jan 1, 2010

By C. M. Brown

The semi-autogenous grinding circuit at the Utah Mines Limited, Island Copper Operation, located on Vancouver Island, British Columbia, is described. Since start-up of the operation in 1971 grinding circuit throughput has been progressively increased from the initial design rate of 30,000 to the current average 45,000 tonnes per day (t/d) of porphyry copper ore. Key developments and modifications in operating and maintenance practice that have contributed to this increase are reviewed.

Jan 1, 1985

By Neil Williams

The brecciated dolostone-hosted (Mississippi Valley-type) and associated shale-hosted stratiform Pb-Zn deposits at McArthur River occur adjacent to a major syndepositional fault, the Emu fault. Base-metal zoning, mineral parageneses, and Pb and stable isotope ratios indicate that both types of deposits formed contemporaneously from metalliferous brines that flowed into the host sediments from the Emu fault. Derivation of brines from underlying evaporitic sediments is suggested. Geochemical evidence indicates that the mechanism of ore formation was sulfate-reduction coupled with oxidation of organic matter. The textural relationships of stratiform sulfide mineralization to diagenetic dolomite concretions, chert blebs, volcanic glass shards, and inter-ore breccia beds, indicate that the reactions proceeded diagenetically within about 100 m of the sediment/water interface.

Jan 1, 1979

By Richard A. Bideaux

With both unit costs per meter and average depth of drilling constantly increasing, there is a strong incentive to maximize the information acquired from drill holes, and then to make this information accessible to the geological staff. The larger the drilling project, the more advantageous computerization of data is over manual methods. The conversion to computer-readable form and the verification of large amounts of drill-hole data can be a substantial data processing task, but once accomplished, the benefits in increased accuracy and speed of interpretation will compensate for the time and effort spent in the work. For an exploration project progressing towards a preliminary feasibility study, about half of both the time and costs for all computer work of the entire feasibility study are devoted to drill-hole data base organization, and maintenance. Once drill-hole results are quantified and verified to be correct, they are immediately accessible and are not subject to further transcription or reinterpretation of errors. To obtain maximum benefits from computer utilization in this area, the drill-hole data base should be set up along with availability of the first data. For some companies, this may initially comprise a large number of purely speculative drill holes on a spacing of perhaps 1 or 2 km. Although few of these drill holes may encounter economic material, thought should be given, at this time, to the variables which will be logged when such material is found. In this way, it should be possible to set up a consistent format into which all future drill-hole information will readily be accommodated. This format may even be carried over into the data base requirements for an operating property.

Jan 1, 1979

By Robert Labbe

The final tunnel lining for this project involved pumping vast quantities of concrete over large distances under the extremely busy streets of lower Manhattan. Approximately 68,000 cubic meters (89,000 cubic yards) were pumped from various locations over 152 meters (500 feet) below ground (Figure 1) to create nearly 14.5 kilometers (9 miles) of 3.05 meter (10 foot) diameter tunnel. Total distances pumped exceeded 1,645 meters (5,400 feet) horizontally after a vertical difference of over 152 meters (500 feet). The urban setting of the operation, coupled with the long distances over which concrete was pumped, created many problems which had to be dealt with along the way. A three-shift labor operation was implemented to allow sequential pouring of tunnel sections nearly every day. The fine tuning of the mix design was critical to make this operation successful.

By T. H. Chan

As the University of Hong Kong and their advisors planned their new Centennial Campus it became clear that they would have to re-provide existing water reservoirs on an adjacent site with new salt water reservoirs located underground in two new caverns. The existing reservoirs are owned by the Water Supplies Department who provide salt water for sanitary flushing and a separate potable water supply for regular use. Although underground reservoirs had not previously been adopted locally, the planning has been completed to a tight schedule and the construction is well advanced. The need to preserve historic buildings imposed constraints, as did the requirement to minimise potential construction nuisance for the local community and environment. This paper presents the background to the project and the work carried out to develop an innovative, sustainable and environmental acceptable solution. Construction progress to date is also presented.

By William D. Leech

Lebanon used a TBM for the firsttime to excavate a tunnel in the country. A main beam TBM, built in 1979, bored the 3.8 m (12.5-ft) diameter by 4,020 m (2.5-miles) Madiq Tunnel. The TBM bored through karstic terrain of dolomitic limestone, limestone and marly-limestone rock having near horizontal beds with more than twelve faults crossing the axis of the tunnel. The TBM also encountered more than six major karst features, filled with various combinations of boulders, clay, void space and water. The excavation through these collapsed-breccia zones drastically slowed the TBM?s progress. When complete, which the Madiq Tunnel is a part, the Kesrouane Water Project along the coast will bring fresh and irrigation waters to the parched and heavily populated region north of Beirut. The paper will describe the tunnel geologic features, karst genius, TBM upgrades and performance, and TBM/karst difficult situations

By R. L. Howell, L. C. Atkinson

Typical sedimentary sequences overlying coal seams consist of interbedded sandstones, siltstones, shales, and rider coal seams. In many surface coalmine settings, these sediments are saturated; and prior dewatering of them is necessary for effective and economic mining, including the stacking of saturated spoils. Such sedimentary sections usually have a very low vertical hydraulic conductivity that does not allow them to drain in a timely manner prior to their being stripped. One potential solution is installation of drainwells. Drainwells are small diameter wells that can collect water laterally from the various more permeable layers in the overburden and then gravity drain it to a lower layer – often the coal seam being mined – where it can be removed by pumping wells or sumps located in the bottom of the pit. A ground-water flow model utilizing the 3-dimensional finite element code MINEDW has been used to evaluate the effectiveness of usingdrainwells in a hydrogeologic setting that is typical of the Powder River Basin. A series of numerical simulations were completed using various combinations and spacings of drainwells and pumping wells to dewater the overburden and coal seams. The numerical simulations suggest that drainwells can be a very effective method of overburden dewatering.

Jan 1, 2000

By R. Codell, D. L. Hughson

While benchmarking the integrated finite-volume code MULTIFLO against the analytical solution of Philip et al. (1989) for cylindrical underground openings, we found numerical simulation of dripping threshold flux consistently higher than the analytical solution for both rectangular and unstructured grids. The magnitude of error is proportional to the alpha parameter characterizing capillarity. This may bias estimates of repository performance towards non-conservatism.

Jan 1, 2000

In this study, a 3D model of the shovel motion based multi-body system dynamics in the Automatic Dynamic Analysis of Mechanical Systems (ADAMS) environment was developed. The kinematics model of the shovel was modeled as a multi-body system, which comprises the lower, upper, and the attachment mechanisms. The Euler-Lagrangian equations were employed as the computational framework to describe the dynamic behavior of the model. A virtual prototype of the shovel was built in the ADAMS software environment. This environment allows the visualization of a 3D motion of the general mechanical system and the prediction of interference of the moving components of the shovel. The numerical analysis and animation of digging, swinging and dumping motions for the shovel were performed. The superimposed display of the deployment for the shovel in three phases allows a detailed examination of the dynamic interference among assembly components. This research provides a solid foundation for further shovel dynamics performance studies. Keywords: Shovel, Spatial Kinematics, Virtual Prototype, Visualization

Jan 1, 2009

By J. A. Flinn

Phelps Dodge’s Morenci copper mine has had six drills, six track-dozers, 16 shovels, two loaders, and 90 haul trucks equipped with either Caterpillar, Aquila, or Modular GPS systems for nearly three years. The Caterpillar Computer-Aided Earthmoving System is an open-architecture system, which allows for inputs to enhance orientation solutions and system functionality. This system has begun a new phase that leads to an intelligent mining system. Optimization techniques of the current system and inputs are reviewed. In addition, some practical issues of implementing new technology in a mining environment have been identified to aid in this new phase.

Jan 1, 2000

By M. Fustic, A. H. Paul

The geology of the Muskeg River Oil Sands Mine is described to demonstrate how geologic modeling aided in resource evaluation and material characterization during the feasibility and construction stages. Bitumen is hosted in the clastic sediments of the Cretaceous McMurray Formation which is informally divided into members representing the fluvial, estuarine and marine environments of this transgressive sequence. Lithofacies mapping of drill core provides further detail to classify materials as resource type, for extraction suitability and for construction suitability. Geologic interpretation provides tools for the engineers to produce effective mine plans and for the operators to execute them during mine development.

Jan 1, 2002

By J. Donovan Jacobs

Many improvements in the art of underground excavation have appeared during the past two decades. These improvements have been both in methods and in machinery and have resulted in more economical construction of today's tunnels. In the realm of machines, the developments of continuous boring heads for either soft ground or rock, random arm excavators and the sliding tunnel floor (Magic Carpet) have each made contributions toward more rapid tunneling. CONTINUITY OF ADVANCE Tunnel boring machines are often referred to as "continuous excavators". Continuous advance (without cyclical interruptions) has not been achieved, however, in any of the machines now in use. In most rotary-head tunnelers the thrust needed to make the cutters bite into the face is obtained from hydraulic cylinders reacting against anchoring devices held stationary by pads which grip against the sides of the tunnel. With this system the forward motion of the cutting head is continuous only until the propelling cylinders have reached their limit of extension. At this point the grippers must be released, moved forward and reset before a new cycle of advance can be begun. Some machines are built to obtain their propelling thrust from hydraulic cylinders pushing backward against newly-installed rings of tunnel support. This is the customary method for propulsion of shields. With it, each cyclical advance or "shove" must await the erection of a new ring of supports. Faster tunnel driving

Jan 1, 1974

By Richard C. Mayberry

Phosphate reserves have been and still are a controversial subject. Some published estimates are particularly conservative and have caused concern in government and political circles that southeastern phosphates are a dwindling resource. "Ores and ore bodies" are a function of economics that relate to a time/demand factor. The history of phosphates and other mineral commodities is one of mineral deposits (resources) ever becoming ore (reserves) via a long term logic based on price, supply, and demand factors operating through time and improved technology. Projections indicate that southeastern phosphates are sufficient for several centuries of operations at present production rates.

Jan 1, 1981

By Horst Pöchhacker

The largest structure along the Tauern highway section between Salzburg and Villach is the 6.4-km-long Tauern Tunnel. The major geotechnical problems that came up surprisingly while driving the headings of that tunnel and their successful solution form the content of this article. A detailed discussion is presented of the special construction methods developed by systematic application of the principles of the New Austrian Tunneling Method with which even very heavily squeezing ground with large excavation areas can be mastered reliably and economically.

Jan 1, 1976

By Wayne Green

The Regional Municipality of York, located north of the City of Toronto in Ontario, Canada, has experienced unprecedented growth during the past decade, with new home construction averaging 15,000 units per year. This rate of growth is planned to continue well into the future with a projected growth of more than 500,000 new residents by 2031, combined with a tar-get of more than 300,000 new jobs to provide a sustainable economic base for the region. It should be noted that York region has been designated as one of the key growth centers by the province of Ontario, aimed in part to meet the housing and employment needs of Canada?s growing population. York Region is a mix of urban and rural areas and is one of the most desirable areas to live in Southern Ontario. York region offers an attractive lifestyle, with its nine municipalities and the amenities created by the many rivers, streams and protected greenbelt areas that encompass more than 69 per cent of the region?s area.

Jan 1, 2010

By Edward O. Reinbold

The paper presents the results of a study which involved collection and analysis of airborne pollutant concentration data in two producing underground room and pillar metal mines which use diesel powered equipment in the area near the face. The results include the concentrations of CO2, CO, NO, NO2 and respirable particulate matter measured with the latest portable instruments, and the carbon and hydrogen contents of the particulate matter samples determined by combusting them in a Elemental Analyzer. The carbon and hydrogen contents are used to estimate the amount of diesel particulate matter in the mine ambient air. The short term grab sample concentration data, although not suitable for determining compliance with ACGIH Threshold Limit Values (TLVs), are related to the TLVs so that they may be compared conveniently. Lognormal frequency distributions and the arithmetic mean of the concentration measurement data are used to compare different mine situations. Conclusions are drawn as to which pollutants are most important to control under actual mine production conditions.

Jan 1, 1979

By Roger L. King

Working in gassy ground conditions is an everyday occurrence for the U.S. coal mining industry. As tunneling operators begin to venture into projects that expose them to the additional hazard of potentially explosive atmospheres, lessons learned by the mining industry over years of experience should be transferred into this industry. This paper will present practices developed by the U.S. coal mining industry for dealing with the problem of excavating material in potentially explosive atmospheres. Procedures will be discussed that can be used to detect and quantify gas prior to mining that have application to the construction industry. Degasification or drainage practices, including predrainage from vertical and horizontal boreholes, will be discussed. Also, ventilation practices commonly used in the mining industry will be presented.

Jan 1, 1985

By F. S. Kendorski

Several startup or longtime underground stone mines have experienced unanticipated roof control difficulties due to the variable geologic character of the roof strata. Careful mapping of roof conditions, and identification of controlling geologic and mine geometric factors, lead to an understanding of the mechanisms causing roof problems. Factors such as unexpected rolls of the roof strata resulting in a gradual change from strong to weak roof; encountering open water-filled master joints; roof strata delamination due to internal water pressures; local karst features with mud, sand, and water hazards; and sudden loss of limestone roof due to paleo-channel erosion are some recent problems described. Strategies for overcoming these problems are discussed and detailed.

Jan 1, 2002