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By D. P. Richards

Tunneling in carbonate sedimentary rocks such as lime stones and dolomites can be difficult when solution channels or voids are anticipated. Addressing the risk aspects associated with these formations can be done effectively through the Geotechnical Baseline Report (GBR) by properly characterizing the ground and ensuring that the Owner?s and the Contractor?s interests are represented and protected. This paper presents a review of tunneling difficulties in these rocks and includes a review of site investigations, geologic characterization, and presentation in the GBR. Key construction issues are also discussed, including appropriate excavation technology, mechanisms of face support and groundwater control, and quantifying grout takes.

By J G. Webster-Brown, K L. Brown

The Waihi Region is host to many low sulphidation epithermal Au-Ag deposits. The Golden Cross mine located at the head of the Waitekauri River, eight kilometres NW of Waihi, was a gold mining operation that placed significant emphasis on environmental management. An assessment of the influence of this mining project on stream sediment geochemistry (Fe, Mn, As, Cu, Pb, Zn, Cr, Cd, Ni, Ag and Se) in the Waitekauri Catchment has been made. Effective waste management during the mine operation appears to have prevented contamination of stream sediment. Trace metal concentrations in the Waitekauri Catchment sediment have generally decreased since 1987, and are currently mainly below the ANZECC (2000) sediment quality guidelines. However, elevated As levels were recorded in the Upper Waitekauri River and Battery Stream, exceeding guideline values. Elevated levels of Cu, Pb, Zn and Cd were found in the Huanui Stream, a tributary of the lower Waitekauri River. This reflects the influence of past mining operations in the valley, as well as natural weathering of hydrothermally altered Coromandel Group andesite. At a number of sites, Mn concentrations also exceeded sediment quality guidelines, and this may be derived from the remediated Golden Cross mine site.

Jan 1, 2003

By D. W. Levinson, L. E. Tanner

DURING the course of an investigation of the zirconium-iron-tin system the zirconium-iron system was reexamined up to 55 pct* Fe. The alloys pre- visible melting3 and X-ray diffraction studies were made of samples of the alloys. The ferromagnetic properties of ZrFe2were determined by Professor P. W. Selwood* using a modified Faraday balance.4 The zirconium-rich portion of the phase diagram is presented in Fig. 1 and compared with the work of Hayes et al.1 The maximum solubility of iron in ß is somewhat decreased while the eutectic temperature is raised. There seemed to be no change in the eutectic composition of 16 pct Fe. Since the base material was so low in iron content, it was possible to establish the maximum solubility in a between 0.017 and 0.025 pct Fe at the eutectoid temperature. The observation of fine ZrFe, particles in the micro structure of a specimen of 0.012 pct Fe alloy quenched from 700°C indicated that the solubility drops below this composition at 700° C and lower. Further study was made of the intermediate phase ZrFe2. wallbaum5 identified the compound initially as ZrFe2 with a C 15 (MgCu2) structure, placing it at 55 pct Fe stoichiometrically. Hayes et al.1 believed they found the phase at about 47.2 pct Fe and called it Zr2Fe3 but reverted to ZrFe, in the discussion of their paper.6 Jordan and Duwez7 confirmed Wallbaum's work as well as finding the same single-phase structure to about 62.3 pct Fe or Zr0-61 Fe2-18. In order to establish the ternary phase relations in the zirconium-iron-tin systema the exact position of this phase had to be known. This was accomplished by X-ray diffraction, visible melting, and metallographic techniques. Elliott8 obtained a single-phase ZrFe2 X-ray diffraction pattern from an alloy of about 55 pct Fe. This was confirmed in the present study with an alloy of 54.81 pct Fe. However, extra lines (attributable to a or ß zirconium) were found in diffraction patterns of the 47.42 and 49.83 pct Fe alloys. The melting characteristics of these same alloys were studied by suspending 47.42, 49.83, and 54.81 pct

Jan 1, 1960

By T. A. Wheat

"The presently increasing world-wide interest in advanced ceramic materials is generally focussed on their exploitation in both structural and functional applications. With the opportunity to engineer microstructures and thereby closely control and tailor the final properties, there are many new applications being made for these materials in both areas.The scope and some of the applications for functional ceramics are reviewed and examples of the present Canadian activity in this field are discussed.BackgroundThere has been progressively increasing international interest in the development and exploitation of ceramic materials in the last five years. The stimulus for this interest arises from several quarters, each of which are independent of the other.• There is a growing awareness of the strategic nature and vulnerability of supply of the raw materials used to produce high performance metal alloys.• The metal alloys are reaching the upper temperature limit for their performance as structural components in engines.• The dramatic increase in oil prices during the late 1970s focussed attention on the need for reduced consumption in many sectors, i.e., there is a need for more efficient engines that operate at higher temperatures - above those tolerated by the present superalloys.• A number of ceramics, especially the structural materials such as SiC, A120 3, AI20rSi02, Si3N4 and the Sialons are produced using non-strategic raw materials and they can exhibit startling performance-auto turbo-rotors are in production mad e of Si3N4 that operate up to 190000 rpm at 600°C, 150000 rpm at 900°C.• Ceramic s are generally of lower density - significant in the weight-reduction of automobiles such as the replacement of a 20-kg five-segment steel leaf spring with a single segment carbon-fibre reinforced unit of 3 kg. • Ceramics also offer major ad vantages in generating, monitoring or controlling the electromagnetic spectrum whether in bulk or thin-film devices that exploit optical, magnetic, pyroelectric, piezoelectric, electronic and I or ionic conductivity characteristics.The opportunity to combine several of these char acteristics in a single material by composition, processing and microstructural design has resulted in an advanced ceramics industry that had world-wide sales in 1980of $4.2 billion (U.S.)(I) and is predicted to grow to sales in the range $7 to $10 billion by 1990 and $16 to $24 billion by the year 2000(2). However, at present, advanced ceramics account for less than 20010 of the total ceramic market."

Jan 1, 1987

By Jørn H. Thomsen

This paper presents the experience gained and the lessons learned over the last decade within the numerous offshore foundation projects undertaken in the offshore waters of Denmark and Belgium by COWI A/S of Denmark. This experience derives from the close collaboration with, and interaction between the owners, contractors, and engineers in the various stages of project development. In turn, the experience draws on COWI's experience within foundation of large bridges world wide over half a century. Focus is on two pioneering gravity base foundation projects: ? Nysted in Denmark, currently the largest offshore windfarm worldwide with 72 Nos Bonus 2.3 MW turbines in water depths up to 10 m in the relatively benign inner Danish waters ? Thornton Bank in Belgium, where the first phase - comprising 6 Nos REpower 5MW-turbines of a total of 60 - are planned to be built in the rough North Sea in water depths exceeding 25 m.

Jan 1, 2013

Jan 1, 1972

By Rosanna Ginocchio

Ante el aumento de los elementos inorgánicos y orgánicos en los suelos, aire y agua, se genera una preocupación mundial por los potenciales efectos negativos en el medio ambiente. Por tal motivo, se utilizaron métodos físicoquímicos como la vitrificación, electrocinética, y tratamientos químicos que son caros y relativamente agresivos. En ese sentido, el presente texto plantea la biorremediación como un método orgánico que utiliza las especies vegetales para remover contaminantes inorgánicos y orgánicos desde un sustrato sólidos para dejarlos in si tu en formas inocuas.

Sep 1, 2012

By Douglas A. Sloan

Who would believe that young elementary school children could understand something as complex as the mining industry? THE CHALLENGE The challenge of accomplishing this is tremendous. An examination of Canadian school children indicated that they knew very little about the world of work in general, and hardly anything about the mineral resource industry in particular. It calls to mind the story about two youngsters who decided to play house. The little girl played her role well as she went about the house doing things she had watched her mother do every day. When it was the little boy's turn, he grabbed his lunch, waved goodbye to his "wife", jumped on his bicycle and pedalled furiously down to the end of the driveway -- where he stopped. The youngster explained that he saw his dad go out of the driveway each morning, but he didn't know where he went, or what he did on the job. When you stop to consider the number of families today with two working parents, you can begin to appreciate the importance of the opportunities for role identity provided by this project.

Jan 1, 1979

By Gerald P. Scanlan

Control of the dust produced by continuous mining machines in coal mines is generally obtained by water sprays from fixed nozzles mounted on the frame of the machine in back of the cutting head. Mounting the nozzles on the rotating head of the machine closer to the coal cutting bits may improve the efficiency of dust suppression. To test this concept, respirable dust measurements were made during 39 regular production shifts in an underground mine using a Joy 11CM continuous miner. The equipment used, difficulties encountered, and measurements obtained are described.

Jan 1, 1974

By Michel Masse

1. A battery-powered wireless mesh network for dynamic diesel machinery tracking and operating status monitoring. 2. A real-time ventilation model and fan speed optimizer. 3. An OPC server for information interchange. 4. OPC linkage to existing control infrastructure. 5. A Human Machine Interface (HMI) providing data archiving, trending and reporting. 6. Live MS-Excel to interrogate the simulation, controls and optimizer. 7. The battery-powered network mesh also provides SCADA functionality to route optimized setpointsto the fans and automated regulators not linked to PLCs.

Feb 1, 2008

By Rob Robinson

Following a massive rib wall failure along the reclaim belt of the large underground surge bunker at CONSOL?s Bailey Mine, a multifaceted, cleanup and rehabilitation effort was initiated to rapidly stabilize the bunker rib walls and place the bunker back into production. Rehabilitation of the bunker included infilling and re-mining of the failed excavation area, installing a system of horizontal tie-back cable bolts, constructing a large knee wall at the base of the rib, reducing water inflow, and providing drainage for rib water. As a result of the coordinated effort, the bunker was safely placed back into production within 38 days. The 7500-ton surge bunker, an engineering feat in itself, was constructed in 2003 to accommodate production surges from two longwalls. In 2005, 14.8 million raw tons passed through the bunker. The 22-foot wide by 75-foot high surge bunker excavation extends as much a 52 feet below the base of the Pittsburgh seam. The bunker excavation measures 325 feet in length, with feeder and reclaim belt excavations extending the bunker excavation by approximately 500 feet. The massive rib roll, which occurred near the bottom of the reclaim belt slope, measured as much as 45 feet high by 60 feet long. Failure of the rib was attributed to progressive failure of a thick claystone unit present near the slope bottom area. Saturation of the claystone by water inflow, high insitu horizontal stress, and pre-existing rock joints were considered contributing factors. Immediately after rib failure, mine production was temporarily rerouted to a parallel belt. Two bulkheads were then constructed 175 feet apart along the reclaim belt slope, and a customized fly ash-cement mixture was pumped from the surface into the unstable reclaim slope area. A tunnel was then mined through the backfill along the original reclaim slope contour; the new excavation supported by a system of customized steel sets. To assure stability of the adjacent bunker rib wall, a pattern of 70-foot long cable bolts were installed downward from the adjacent entries to effectively tie back the rib. Drainage holes and a 12-foot high knee wall were installed. Adjacent gas wells were also plugged to help reduce inflow. Periodic inspections and continuous monitoring are being used to help assure bunker stability.

Jan 1, 2007

By H. D. Outmans

The paper presents a theoretical approach to the drilling problem based on rock mechanics and drilling fluid hydraulics at the bottom of the hole. The volume of the fractured rock around the vevtically penetrating bit tooth is expressed as a function of the tooth pressure, included tooth angle, drilling fluid pressure and formation characteristics on the assumption that fracturing is preceded by plastic flow. This assumption is verified by comparing the stress-strain state in the rock around the tooth to that in equivalent tri-axial compression tests described in the literature. An expression similar to the above is derived for the tooth penetration in the cuttings which have been retrained at the bottom. Combination of these two expressions leads to a relation between depth of tooth penetration in the virgin rock, the amount of cuttings retained and the other variables. By relating the cutting volume to the drilling rate, the hydraulic bit horsepower and the drilling fluid pressure, it is possible to arrive at formulas which express the drilling rate for viscous or turbulent flow at the cutting surface, for instant clearance, for retained cuttings, or for false tooth foundering as functions of such variables as the drilling fluid pressure, hydraulic horsepower at the bit, rotary speed and bit weight. Plotting the results as drilling curves and comparing them to published field and laboratory data justify the conclusion that the drilling model presented in this paper approximates the actual mechanism. The drilling curves serve to explain some characteristic features of the rotary drilling operation, and the equations may be used for numerical evaluation of the effect of changes in the magnitude of some of the variables on the drilling rate. INTRODUCTION Published laboratory data have established that consistent and relatively simple relations exist between the drilling rate and any one of the important variables. For instance, the drilling rate usually increases at an increasing rate with the bit weight. It increases at a decreasing rate with the rotary speed, decreases at a decreasing rate with increased drilling fluid pressure and plots as an S-shaped curve against the hydraulic horsepower at the bit. This relative simplicity seems difficult to understand considering that the drilling mechanism is a continuous process of generation and removal of innumerable individual cuttings, under different conditions for each. On the other hand, the drilling rate (although determined by this complicated process) only expresses the average rate at which cuttings are produced and cleared away. Ignorance of the drilling mechanism as far as individual cuttings are concerned, therefore, does not exclude the possibility of arriving at a concept of the drilling rate provided the mechanism is properly evaluated for the average cutting. It then may be concluded from the first sentence that this concept also should be rather simple in its final form, although not necessarily in its derivation. Two aspects of the drilling mechanism are difficult to evaluate — (1) the effect a penetrating drilling fluid has on the stresses around a bit tooth entering the formation and (2) the volume of rock fractured by a penetrating tooth which moves both vertically and horizontally. Thus, the scope of this paper has been limited to an evaluation of the drilling mechanism in formations which have a low permeability and are drilled with hard-formation bits. In the following sections, the drilling mechanism is analyzed in three steps. First, the effect of tooth pressure on the volume of fractured rock around the tooth is evaluated, assuming initially that the bottom of the hole is free of cuttings and, then, determining the effect of a layer of these cuttings. In the second section, the thickness of this layer is related to the drilling rate and the chip clearance time, and the latter to the hydraulic horsepower at the bit under conditions of laminar and viscous flow at the cutting surface. In the third section. the previous results are combined with the rotary speed into drilling equations which are then plotted and compared to experimental drilling curves. This section also contains some numerical examples of drilling rate computations. Some mathematical details are given in the appendixes. Finally, it should be mentioned that, although some drilling equations are already available, these equations (with the exception of one' which attempts to relate drilling rate to drilling fluid pressure) are all mathematical expressions for observed laboratory data; none considers the effect of delayed drill-cutting removal, an essential feature of the drilling mechanism.

By G. B. Shea

The accident experience of the California petroleum industry for 1927 was characterized by a decrease it .the number of fatalities. The year closed with a total of 41 fatal accidents, as compared with a total of 54 for the preceding year. 3 In percentage, the figure for 1927 represents a decrease of 24 per cent from that of 1926 and evidences the promising results of organized safety work, in which the industry in California has taken an absorbing interest. The percentage of decrease for 1927 is the largest recorded in any one year since the compilation of the fatality record in the California petroleum industry was begun. Although good progress has been made during the past few years, much remains to be done to reduce still further the human and economic waste caused by accidents. This review is intended to show the employee, as well as the employer, the proximate and contributing cause of accidents. To increase the value of the report, preventive measures in various instances are suggested, on the theory that accidents of a similar nature will occur unless remedial action in taken to remove the cause.

Jan 1, 1928

By Associates

The headwaters of Skippers Creek and the Shotover River are reputed to be among the richest alluvial gold catchments in the world. This alluvial gold has no doubt been derived from reef systems similar to, and associated with, the Bullendale lodes. Physiographically the prospect covers steep ridges and deeply incised gullies between the Richardson Mountains in the west and the Harris Mountains in the east. Vegetation is mainly tussock with bush either side of Murdochs Creek. Access to the area is by metalled road to Skippers and then by 4WD track to Bullendale. Alternatively the prospect area can be reached by helicopter from Queenstown in around ten minutes.

Jan 1, 1992

By P. Wearden, K. Bryner, K. Vrana, V. Castranova, R. Dey, R. Reist, J. Blackford

INTRODUCTION Proliferation and enhanced synthesis of collagen by pulmonary fibroblasts have been shown to be key steps in the development of chronic silicosis (Goldstein and Fine, 1986). The regulation of lung fibroblast proliferation by cytokines released from alveolar macrophages may be an important pathogenetic mechanism in the development of the fibrotic process (Kelley, 1990). One cytokine, platelet-derived growth factor (PDGF), promotes fibroblast proliferation by inducing the movement of quiescent (Go) cells into the C1 phase of the cell cycle (Chen and Rabinovitch, 1989). Others regulate the rate of transition of fibroblasts from Gl into the S phase (Leof et al., 1982). These two classes of cytokines have been termed, respectively, competence and progression factors. One approach used to examine the release of cytokines from macrophages is the fibroblast proliferation assay in which fibroblasts are exposed to culture supernatants from macrophages exposed to various stimuli. In most of these assays, the supernatant contains fetal calf serum which provides the competence factor(s) necessary to facilitate the proliferation of fibroblasts (Bitterman et al., 1982; Bitterman et al., 1983; Elias et al., 1988). Recently, a fibroblast proliferation assay using plateletpoor plasma (lacking competence factor(s)) as a substitute for fetal calf serum has been described (Kuman et al., 1988; Bauman et al., 1990). In this assay, the release of a competence-inducing PDGF-like growth factor from rat and human macrophages can be distinguished from other cytokines that act as progression factors. In order to obtain more consistent results and with the ultimate goal to be able to discriminate between the effects of competence factors as opposed to progression factors, we have conducted experiments to determine the appropriate concentrations of plasma and PDGF required for imparting competence in the fibroblast proliferation assay. We tested lung fibroblast cells obtained from explants of rat lung tissue and also a fetal human lung fibroblast cell line obtained from American Tissue Culture Collection (ATCC153). MATERIALS AND METHODS Fibroblasts Specific pathogen-free, male Sprague-Dawley rats were use in some studies. Animals were given a lethal intraperitoneal dose of sodium pentobarbital. Fibroblasts were isolated by chopping the lung in enzymes that digest the connective tissue but liberate lung cells for further study (Rabovsky et al., 1989). After digestion, the remaining lung tissue suspension was filtered through two layers of sterile gauze and centrifuged to recover lung fibroblasts. These were resuspended in culture medium that contained 10% fetal calf serum and distributed to culture plates for growth. In other experiments, a human fetal lung fibroblast cell line, obtained from American Type Culture Collection, Rockville, MD, 20852, was used instead of rat lung fibroblasts. In these cases, a 1 ml ampule containing human fetal fibroblasts was plated into a tissue culture flask containing medium plus 10% fetal calf serum. For both types of fibroblasts, culture medium was changed 3 times per week and cultures were incubated at 37°C until confluent. Harvested rat and human lung fibroblasts were quantified using an electronic cell counter equipped with a cell sizing attachment (Coulter Electronics, Inc., Hialeah, Florida). Tritiated Thymidine Incorporation The basic procedural outline of Kumar et al. (1988) was used with modifications to evaluate tritiated thymidine incorporation into fibroblast DNA following exposure to PDGF and plasma. Both rat and human lung fibroblasts were plated at 50,000 cells/ml at a density of 250,000 cells/25cm2 culture plate. Cells were quiesced for 4 days with 2% rat plasma. As the assay was refined, fibroblasts were quiesced in plasma-free media for 48 hrs, since the mitogenic activity of 2% plasma was variable. Test medium was applied for a period of 6 hrs, followed by a 24 hr tritiated thymidine (lµCi/ml) labelling period in plasma-free media. Medium alone was used as a negative control and media with 10 or 20% fetal calf serum was used as the positive control for rat and human fibroblasts, respectively. Cell Quantification and Measurement of Mitogenesis Twenty-four hours after the addition of tritiated thymidine, the fibroblasts were washed with 5ml of fresh serum-free media, centrifuged and resuspended in phosphate-buffered saline. The cells were dissolved in 0.5m1 of O.1N NaOH and radioactivity determined in a beta counter. Incorporation of trititaed thymidine as an index of DNA synthesis was expressed as DPM/fibroblast. RESULTS In the present study, we quantified mitogenic potential by monitoring the incorporation of tritiated thymidine as

Jan 1, 1991

By Karina Aparecida Martins Barcelos Gonçalves

Amostras dos aços inoxidáveis duplex UNS S31803 (duplex padrão) e UNS S32304 (lean duplex) foram investigadas no estado de fornecimento, após laminação a frio com redução de 64% e 62% e recozimento na temperatura de 1055ºC com 20s de encharque. Foram medidas a dureza Vickers e a quantificação das fases, austenita e ferrita, usando o método de contagem por pontos. A textura cristalográfica foi obtida via técnica de EBSD. A textura cristalográfica da fase ferrítica no estado de fornecimento e recozida apresentou as fibras a //DL e q {100} //DN mais intensas, enquanto a fibra g {111} //DN aparece com intensidade menor. Na fase austenítica as principais componentes encontradas com maior intensidade estão na fibra a //DN e na fibra b com menor intensidade.

Jan 16, 2018

By Guilherme Duarte Moreira

Com o objetivo de melhoria dos resultados de desempenho operacional identificouse uma oportunidade em reduzir o tempo de trocas programadas (Setup) na Laminação de Fio Máquina na Usina Siderúrgica de Ouro Branco. Utilizando a metodologia SMED (Single Minute Exchange of Die), obteve-se grande redução do tempo de Setup. Como esta metodologia já se demonstrou uma excelente ferramenta para redução dos tempos de setups, foi idealizado uma abordagem mais completa, sendo desenvolvido um modelo para aplicação para as paradas programadas para manutenção. Esta aplicação corroborou um enorme ganho, tanto na definição do tempo de parada programada, quanto no planejamento e padronização das atividades.

Aug 16, 2017

By Verya Nasri

The Silver Line Phase III Project is the final one mile underground segment of the new Bus Rapid Transit in downtown Boston. The project is expected to significantly reduce existing and anticipated traffic congestion. The twin one-lane tunnels and two station platforms will be built by NATM in Boston saturated soft clay, sand and till layers in proximity to several historical buildings, underpinning two existing cut and cover subway stations and several major utilities in densely built urban area. This paper presents the analysis and design of the NATM tunnels and stations detailing the excavation sequence and support system and various ground improvement and pre-support techniques used in the preliminary and final design of the project

Underground equipment owners and users in order to compete and succeed in being viable business propositions must continually balance costs with productivity. By reducing their hourly ownership, operation and maintenance costs and increasing their hourly production, the cost per unit of material mined will be optimized.

Jan 1, 1990

By Laura McNally

In 2006 McNally International Inc. in a Joint Venture partnership with Aecon Constructors was the successful bidder on two York Region Tunnel Projects: Bathurst Collector/Langstaff Trunk Sewers; and YDSS Interceptor Sewer 19th Avenue Project. These projects comprise a total of 13 kilometres of 2.74 meter finished diameter tunnels and are both part of the York Durham Sewer System (YDSS). Both contracts require the use of EPB tunnel boring machines with a precast concrete segmental liner. The following provides an overview the two projects.

Jan 1, 2008