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By Cyril Smith

ISOLATED alloys of copper and silicon were prepared and examined by chemical methods more than one hundred years ago, but it was not until the work of Rudolfi1 that the equilibrium relations. were studied. The early history of the alloys was well described by Baraduc-Muller2 PERCENT SILICON-BY WEIGHT FIG. 1.-COPPER-SILICON EQUILIBRIUM DIAGRAM ACCORDING TO RUDOLFI (1907). and need not be further discussed here. The diagram of Rudolfi, based entirely on thermal observations, showed silicon to be soluble in copper up to 4.5 per cent. at 849° C., at which temperature there was a peritectic horizontal resulting from the formation of a 0 phase with about 7.4 per cent. silicon from a and liquid with 7.85 per cent. silicon. The ß phase was believed to form a eutectic with Cu3Si at 820° C. and 9.8 per

Jan 1, 1928

By Robert I. Jaffee, Bruce W. Gonser, Eugene M. Smith

THERE has been little investigation of the gold-germanium binary alloys. Haughton1 does not mention any work on the system. In a review article commemorating the fiftieth anniversary of the discovery of germanium, E. Einecke2 mentioned a gold germanium eutectic at 24 atomic per cent Ge (10.4 weight per cent) melting at 359°C., but did not give the source of his information. From measurements of electrical conductivity, J. 0. Linde3 estimated that at least o.6 weight per cent germanium is soluble in gold. The recent availability of germanium in this country in commercial quantities has led to interest in its properties and its alloys. This study is part of a program of investigation on germanium alloys; work on ternary alloys involving germanium and gold will be reported later. In this investigation, the composition and melting point of the Au-Ge eutectic reported by Einecke has been found to be substantially correct. Eutectic composition has been placed at 12,0 per cent germanium, however. An alloy of 10.4 per cent Ge, Einecke's value, was found to have a few gold dendrites in it. The eutectic temperature has been determined as 356.0 ± 0.5°C., slightly less than the temperature of 359°C reported by Einecke. The liquidus curves and the solid solubility of germanium in gold have been determined, and are shown in Fig. I. MATERIALS AND ALLOYING The germanium used in this investigation was prepared by the Eagle-Picher Lead Co. from pure germanium oxide, by reduction in clay crucibles with sodium cyanide. The regulus is quite pure, assaying over 99.9 per cent Ge. High-purity gold obtained from Handy and Harmon was used. Alloying was carried out in graphite crucibles in an atmosphere of purified hydrogen. The temperature was brought up to 1050° to 1100°C., and the metal was allowed to freeze in the crucible. Prepared in this way, the gold dendrites in hypoeutectic alloys were somewhat segregated at the bottom and sides of the ingot, and on the hypereutectic side the lighter primary germanium tended to gather at the top. Most of the alloys were made from virgin metal. Low-germanium heats were made by alloying pure gold with the eutectic. Melting losses were consistently a few milligrams or less, and the composition could safely be taken from the intended analysis. The 30 per cent and 50 per cent germanium heats for thermal analysis were made in part from remelted higher germanium heats, and they may be off composition as much as one per cent. Because of the high cost of materials, the weight of heats for thermal analysis were 15 to 20 grams and heats for metallographic, X-ray, and hardness specimens were 2 to 4 grams.

Jan 1, 1945

By M. G. Corson

THE iron-silicon alloy series has always been one of the most puzzling among the binary alloys. Examining the well known mechanical properties of the iron-rich alloys only we meet the following situation: The ultimate strength and yield point of alloys worked and annealed under the usual conditions represent nearly a straight line function of the silicon content up to 4.5 per cent. silicon (Fig. 1). Starting at the ultimate strength of 35,000 lb. and at a yield-point of 16,000 lb. for pure electrolytic iron, one reaches a -maximum strength of 93,000 lb. and a maximum yield point of 74,000 lb. at 4.5 per cent. silicon. This corresponds to an increase in ultimate strength by 13,000 lb. per each per cent. of silicon added and nearly the same rate applies to the yield point. The data mentioned are taken from the investigation by T. D. Yensen,1 and while they do not exactly corroborate the results obtained by earlier investigators, they seem to be the most correct. Plastic properties of the alloys are controlled by a much more complicated relationship. Up to 2.5 per cent. Si, the elongation stays close to 50 per cent. (in 2 in.) and the area reduction amounts to 85 per cent., a situation that forms the usual feature of all alloys representing strictly solid solutions. The plasticity of the latter is always nearly equal to that of their base metal. Beyond 2.5 per cent. silicon, the situation becomes much more complicated Yensen observed an enormous drop in elongation and area reduction at about 2.65 per. cent. silicon, where the first hardly reaches 10 per cent. and the second is still lower; he found, however, a considerable recovery in plasticity at about 2.8 per cent. Si and up to. 4.5 per cent. Si it is represented by 20 per cent. for the elongation and 30 per cent. for area reduction.

Jan 1, 1928

By M. G. Corson

THE iron-silicon alloy series has always been one of the most puzzling among the binary alloys. Examining the well known mechanical properties of the iron-rich alloys only we meet the following situation: The ultimate strength and yield point of alloys worked and annealed under the usual conditions represent nearly a straight line function of the silicon content up to 4.5 per cent. silicon (Fig. 1). Starting at the ultimate strength of 35,000 lb. and at a yield point of 16,000 lb. for pure electrolytic iron, one reaches a maximum strength of 93,000 lb. and a maximum yield point of 74,000 lb. at 4.5 per cent. silicon. This corresponds to an increase in ultimate strength by 13,000 lb. per each per cent. of silicon added and nearly the same rate applies to the yield point. The data mentioned are taken from the investigation by T. D. Yensen,1 and while they do not exactly corroborate the results obtained by earlier investigators, they seem to be the most correct. Plastic properties of the alloys are controlled by a much more complicated relationship. Up to 2.5 per cent. Si, the elongation stays close to 50 per cent. (in 2 in.) and the area reduction amounts to 85 per cent;, a situation that forms the usual feature of all alloys representing strictly solid solutions. The plasticity of the latter is always nearly equal to that of their base metal. Beyond 2.5 per cent. silicon, the situation becomes much more complicated. Yensen observed an enormous drop in elongation and area reduction at about 2.65 per cent. silicon, where the first hardly reaches 10 per cent. and the second is still lower; he found, however, a considerable recovery in plasticity at about 2.8 per cent. Si and up to 4.5 per cent. Si it is represented by 20 per cent. for the elongation and 30 per cent. for area reduction.

Jan 1, 1928

By B. Blumenthal

THE present investigation was planned as a survey of the lead-rich portion of the ternary lead-antimony-silver system by thermal analysis. Since, however, a rigorous application of the conventional thermal analytical method is time consuming, an attempt was made to speed up the investigation by reducing the time required for a single thermal analysis. This was done by increasing the rate of cooling to 12° to 18°C. per minute. Since such a rate does not permit even an approach to equilibrium conditions, the melt was stirred vigorously by a stirrer operating at the high rate of 665 r.p.m. This proved to be effective in obtaining cooling curves with distinct points of arrest and of excellent reproducibility, which satisfactorily compare with those obtained at a rate of 1° to 2°C. per min. with or without slow stirring (Fig. 1). By this method the lead-rich end of the lead-antimony system and a series of ternary alloys in sections parallel to the lead-antimony side of the ternary system were investigated and it was observed that the two branches of the' liquidus curve of the .binary alloys did not intersect at the eutectic temperature. An equivalent effect was observed in the ternary system. The eutectic temperature of the binary lead-antimony system was found to be 252.0°C., which confirms the recent investigation by Pellini and Rhines,1 who determined the eutectic temperature to be 251.5°C. The observation that the curves of primary crystallization of the lead-antimony system do not intersect at the eutectic temperature was previously made by Dean.2 Dean explains the phenomenon by assuming the existence of a compound Sb4Pb. He felt that super-cooling was not the cause of the phenomena because he was unable to influence them by inoculation. The X-ray investigation by Solomon and Morris-Jones,3. the metallographic investigations by Stead,4 Charpy,5 Gontermann,6 and Dean, Zickrick and Nix,7 and the numerous investigations of physical properties, definitely disprove the occurrence of any compound. The work of Dean was not confirmed by Broniewski and Sliwoski,8 whose experiments did not show any irregularity and who report a eutectic composition of 13 per cent antimony and a eutectic temperature of 250° to 252°C. at a rate of cooling of about 6°C. per min. Abel, Redlich and Adler9 then report a eutectic composition of 12.1 per cent upon reviewing the previous, publications and adding a few of their own cooling curves. In 1934 Quadrat and Jiriste10 found from careful analyses of the bottom portion of slowly cooled hypereutectic melts that the eutectic contains only 11,4 to 11.5 per cent antimony. (Previous analyses by Stead4 in 1881 gave 13 per cent:) Weaver," however, reported in 1935 that cooling curves indi-

Jan 1, 1943

By Samuel Hoyt

THE writer has long been interested in seeking an explanation of the upper heat effect in the copper-tin alloys over the a + ß range, first described in 1913. These notes are offered, not at all as the final explanation of this heat effect, but rather to indicate certain progress which has been made toward establishing what happens over this temperature interval. While working on the thermal analysis of the copper-rich kalchoids (copper-tin-zinc alloys), it was noted that those alloys containing major portions of tin and minor portions of zinc exhibited two marked heat effects, one at about 520° C. and the other at about 600° C., instead of the single effect which is generally observed in either of the two binary series. This matter was discussed with Dr. Guertler, who suggested that a heat effect at about 600° C. in the pure copper-tin alloys might be expected. This led to a more searching examination of the thermal critical points in the pure copper-tin alloys, with the result that a marked, although somewhat weak, heat effect was located at about 600°. Somewhat later, this upper heat effect was discussed with Dr. Burgess, and it was requested that the Bureau of Standards make heating and cooling curves of one of these alloys for the purpose of removing any possible doubt as to the actual presence of the heat effect. Results obtained by the Bureau are given in Plate I. In an earlier paper1 differential curves were published showing that the heat effect occurred at constant temperature over the a + ß range and increased in magnitude with the amount of a up to a point somewhat above 20 per cent. tin. No heat effect was noticed at this temperature in the eutectoid alloy. The existence of this heat effect seems to require a modification of the present copper-tin diagram in the a + ß field, and it has been the object of the work here presented to secure the evidence upon which such a change should be based.

Jan 12, 1918

C. H. BIERBAUM,* Buffalo, N. Y.--I agree with Dr. Merica that the eutectoid has a distinct effect upon the alloy and also that, as yet, it is difficult to say at just what point this eutectoid occurs or the conditions under which it appears; that is, the percentages of copper, tin, zinc, lead, and the other elements together with the temperature of pouring and the rate of cooling that is necessary; all seem to have a contributing effect. Some authorities, Law for instance, gives it as 9 per cent. of tin, yet under certain conditions I have found it with a lower percentage of tin to copper contents than that. The hard delta and the soft alpha crystals are both necessary for a bearing alloy; the one supplements the other. I am not inclined to think that phosphorus has any effect upon the eutectoid forming. The phosphide, PCu3, forms in and around the delta but is and remains distinct and separated from it. Etching with ferric chloride and then with nitric acid shows this very distinctly; it darkens the eutectoid and the other parts and leaves the phosphide bright. The rate of cooling determines the size of the crystals and the eutectoid together with their distribution and orientation. It is possible to chill the alloy to such an extent Where no eutectoid appears. I think it has been positively demonstrated that only an alpha and a beta appear. when this copper-tin alloy has been poured between two polished ingots

Jan 1, 1919

By Ernest Naesgaard

Post-grouted micro-piles were used for the seismic upgrading of the Vancouver International Airport Domestic Terminal Building (DTB). The micro-piles provided vertical resistance to both uplift and compression loads to supplement the existing timber pile foundations ability to resist the earthquake induced forces, and to provide foundation support at locations where the installation of traditional driven piles was difficult. This paper describes the site conditions, design rationale, installation method and quality control testing procedures. Site and Subsurface Conditions Vancouver International Airport is located within the central portion of Sea Island, Richmond, British Columbia (Fig. 1). Sea Island is bordered by branches of the Fraser River on the northeast and south sides and the Strait of Georgia along the west side. The natural grade of the island is part of a large delta that has been built up over several thousand years. The general pattern of sediment deposition has followed the direction of the Fraser River flow from east to west, and has built up soft sediments of about 200 m thickness at Sea Island (Luternauer, et al. 1993, Mathews and Shepard 1962). The original grade in 1962 prior to the existing Airport Terminal Building development was at about geodetic elevation 1.1 m with a grass and topsoil cover.

Jan 1, 2004

By Donald A. Bruce

The paper reviews aspects of the construction and performance of prestressed ground anchors installed in soils and weak rocks. Attention is focused on good practice for drilling, tendon fabrication and handling, grouting, stressing and testing. Regional variations - not always logically justified - are described. The performance of anchors in a variety of geological conditions is illustrated with reference to recent full scale test programs. 1. Introduction In the United States there has been steady growth in the use of prestressed anchors in materials other than competent or hard rock, in the years since their introduction in the late 1960's. This expansion has to a large extent been driven by specialty geotechnical contractors who both imported foreign developments and conducted their own basic researches, in locally prevailing conditions. With such data and experience, these engineers have had the confidence to promote "alternative solutions" for difficult earth support problems to receptive designers and owners. In turn, being engaged in the details of design and performance monitoring has given these parties the close exposure necessary for the real transfer and understanding of the technological concepts, and this knowledge has generated positive feedback for the contractors.

Jan 1, 1991

By Braden T. Lusk, Rex A. Meyr, Kyle A. Perry

Following three major mining accidents in 2006, the MINER Act of 2006 was enacted by MSHA and required every underground coal mine to install refuge alternatives to help prevent future fatalities of trapped miners in the event of a disaster. A polycarbonate safe haven wall for use in underground coal mines was designed and modeled using finite element modeling in ANSYS Explicit Dynamics to withstand the MSHA required 15 psi (103.4 kPa) blast loading spanning 200 milliseconds. The successful design was constructed in both half-scale and small scales in the University of Kentucky Explosives Research Team’s (UKERT) explosives driven shock tube. The constructed polycarbonate walls were tested multiple times to determine the walls resistance to blast pressure. The results for each test were analyzed and averaged to create one pressure versus time waveform which was then imported into the finite element program and modeled to compare deflections of each part to that was measured during testing for model validation. This paper summarizes the results.

Jan 1, 2014

By Roy A. Grancher

Construction materials indeed face a dilemma...as does the building industry as a whole. A stop & go economy; a severe drop; in housing starts; lingering indecision over just what corrective steps are to be taken or to their degree of commitment; no less basic disagreement in regard to which of the, Nation's problems is really the most pressing -- inflation or recession? Optimism has become a rare quality these days. At moat the cautious view is that this new year will see a long, hard struggle back, with hopes that 1976 at least can truly mark a dual anniversary celebration for the United States and its economic health. Yet the paradox is that once recovery does return, those very construction minerals and materials --which in recent years have experienced the ups and downs of overcapacity, shortage, and now declining demand again-- will once more face the spectre of mass inability to service revived and growing needs for its product. Mounting costs, present marginal expansion investment, and substantial lead times required for new facilities to come into production, could well form a bottleneck to economic upswing. The result again can be another cycle of shortage-induced inflation, and with it continued gyrations within the demand supply relationships of the country's building industries.

Jan 1, 1975

By H. Martyn Chance

I HAVE been induced to present this paper to the Institute because I have been unable to find any publication containing a discussion of this subject. In some of our technical schools and colleges the student is required to construct or copy (generally the latter) a number of profile sections as part of his routine work ; but little attention is given to the methods of projecting observed dips and exposures upon the section line, and still less to the method of con¬structing the under (or above) ground curves. As a result of this lack of instruction every engineer or geologist is compelled to invent for himself a system, or copy the style of others. Geological profile sections have frequently been used to determine underground structure from data obtained at the surface, but the experience of engineers in the anthracite coal-fields has shown that they are to be relied upon only in exceptional instances. The possibility of indicating underground curvatures from dip-angles observed at the surface has been found to be limited to a mere approximation of the larger flexures, As a means of predicting the depth and shape of minor rolls, they have been found most unsatisfactory. In the anthracite coal-fields the hypothecatod

Jan 1, 1881

By R. Kus´

The paper presents the comments on the advantages of implementing an integrated system of managing mining exploitation in hard coal mines, as well as the comprehensive integration of information on the process of deposit exploitation with economic data, so as to achieve an optimum technical and economic effects. The principles of constructing the production management system have been presented, thanks to which the management boards are provided with reliable technical and economic information on a mining company via information technology. The strategic direction of a company’s operation may currently be verified according to the external conditions that change over time (the information on the deposit, force majeure events, changing expectations of customers, etc.).

Jan 1, 2003

By Peter A. Gillett, Ian S. Clelland, J. G. S. Hynd

Today mine shaft and slope contracts include a greater amount of ancillary work such as level and pump stations, loading pockets, rotary and side dumps and connecting raises. This ancillary work requires the application of a number of construction methods often for short periods and often at short notice if the contractor is to maintain a profitable operation. In the next decade, the number of shafts that will be sunk by a boring method will outnumber those sunk by traditional methods. This will be particularly true of the deeper shafts where water problems are minimal. The increase of bored shaft work will not decrease the work completed by the shaft sinking contractor but it will change it. A greater emphasis will be placed on the speed of construction of station and other ancillary work. To meet this challenge the contractor requires full information on the ancillary work as well as the shaft work at an early date, preferably pre-bid. The two examples discussed in this paper illustrate the importance of early information. The two main factors of shaft ancillary work construction are sequence and ground support. This paper describes two examples completed recently by The Cementation Company of America Incorporated in Arizona. The first described is a Rotary Dump-Ore Pocket-Ore Pass complex and the second described is the excavation of the Main Station Level in a 2 Station-Loading Pocket-Ore Pass complex. CONSTRUCTION OF ROTARY DUMP, ORE POCKET AND PASS Introductory

Jan 1, 1976

By Leonard W. Postregna

Prior to January, 1986, the city of Austin, Texas was on notice by the Federal Government's Environmental Protection Agency and the Texas Water Commission, that they were illegally polluting the Colorado River. The wastewater facilities presently in use in South Austin were inadequate to handle the vastly increasing population. The city of Austin, Texas hired Parsons Brinckerhoff Quade and Douglas, Inc. and Dannenbaum Engineering Corporation to design and supervise the construction of an update to their existing system to alleviate this problem. A major criterion handed down to the Designer and Contractor was that the system had to be completed within a two year time frame. The biggest link to the entire design was a tunnel project consisting of 43,000 linear feet (13,106 m) of tunnel, eight feet (2.44 m) in diameter with connecting structures tying into existing and future facilities. The project was awarded to S. A. Healy Construction Company of McCook, Illinois with a low bid of $24,755,000.00. This article summarizes the techniques used in the construction of this tunnel project.

Jan 1, 1989

By Edward (Ted) Dowey

City Water Tunnel No. 3 is being built in order to provide a redundant system for delivering 4,542,500 m3 (1.2 billion gallons) of water per day throughout the five boroughs of New York City. The present tunnels, City Tunnel No. 1 and 2 (Figure 1), were put in service in 1917 and 1936 respectively, and both have been in continuous service. Tunnels No. 1 and 2 can-not be shut down for inspection or repair until City Tunnel No. 3 has been completed. City Tunnel No. 3 has two stages (Figure 1).Stage One is 20.1 km (12.5 mi) long and is presently delivering drinking water to the boroughs of the Bronx and Manhattan. Stage Two consists of the Brooklyn-Queens Tunnel 17.7 km (11 mi) and the Manhattan Tunnel 14 km (9 mi). The Brooklyn-Queens leg is complete and is set to be put in service soon. The Manhattan Tunnel is being constructed and is the subject of this paper. The Manhattan Tunnel (Figure 1) is comprised of three legs: the north, south and east legs. The con-tract includes the excavation of 8,976 m (29,500 ft) of tunnel and the lining of 14,561 m (47,773 ft) of tunnel. The south tunnel, 5,705 m (18,720 ft), was excavated but not lined, under a previous contract. The tunnel ranges from 181 m (600 ft) to 152 m (500 ft) in depth in the bedrock under Manhattan. The tunnel contract also includes the construction of nine new shafts, 161 m (530 ft) average depth, and the completion of a tenth shaft (the previously built construction shaft). The Manhattan Tunnel contract was awarded to the sole bidder Schiavone/Shea/Frontier Kemper Joint Venture (SSF) for $668,532,680.00, on January 31, 2005. The Manhattan Tunnel was designed ?in house? by the New York City Department of Environmental Protection (DEP) and the construction management was provided by a combined staff of the DEP and a joint venture of Jenny Engineering and URS.

Jan 1, 2008

By B. Boutilier, R. Mendoza

"First Majestic Silver Corp. (FMS) is a silver mining company founded in 2002 that operates exclusively in Mexico. It has six producing silver mines, one of which is the La Encantada silver mine (La Encantada) located in the state Coahuila. La Encantada is located near the southern United States border and 708 km (440 miles) north of the city Torreon.La Encantada is located in the Sierra Madre Oriental and is a high-temperature carbonate replacement deposit. Mineralization in La Encantada occurs in many different forms such as veins, chimneys, breccia pipes and reefs (mantos). Mineralization is mainly oxides of iron, zinc, lead and manganese, with high concentrations of sulfides at depth relating to two main intrusive events: the Milagros Intrusive and the La Prieta Skarn.Mining began in La Encantada during the 1950s with small vertical shafts, drifts and raises. It focuses on the high-grade silver zones using traditional hoists and extraction methods, before branching into two main separate mining camps: El Plomo and Penoles camp. Penoles, the previous owner, focused mainly on large ore bodies using post pillar cut-and-fill mining method to extract the higher-grade material. Due to the type of ground, irregularity of pillars, and rock conditions, large amounts of high-grade pillars had to be left in situ to ensure the stability of the excavations. The mined-out areas would then be filled with lower-grade material to assist in the stability of the secondary level. These room-and-pillar development entries were 2.5 m x 2.5 m (8.2 ft x 8.2 ft) and spaced every 10 m (32 ft), leaving a vertical pillar of 7.5 m (25 ft). First Majestic acquired La Encantada in 2006. After the acquisition of the mine, the company began the conversion of the surveying reference system from a local grid (Maria Isabel Shaft as 0,0) to the Nav27 coordinate system, and subsequently converted to the WGS84 coordinate system in 2015. Due to the extensive history of the mine, different areas were surveyed with different systems, causing significant challenges when designing the principal extraction levels, pillar heights and ramp locations. To overcome this difficulty, the entire mine was resurveyed and the old workings transposed to the new coordinate system, except for some inaccessible areas due to poor ground conditions or ground collapses. To further ensure pillar height and the safety of the mine workers, probe holes were drilled during the development process."

Sep 1, 2019

By C. S. Oteo, H. Suárez, P. de la Fuente

ABSTRACT: In the south of the Island of Gran Canaria (Spain) there appear layers of swelling clays inside volcanic formations of a fonolitic type, down to depths as low as 500 m, with thicknesses of 1 to 3 m. Two tunnels (each of length 1,500 m) have been built in these zones (ignimbrites and swelling clays), work on which started in the ‘70s. The construction has been influenced by phenomena of expansivity and decompression. Presented below are the problems that arose, the field and indoor studies conducted and the numerical optimisation of the lining. ZUSAMMENFASSUNG: Im Süden der Insel Gran Canaria (Spanien) kommen im Inneren vulkanischer Formationen phonolithischen Typs in Tiefen von bis zu 500 Metern 1 bis 3 Meter dicke Blähtonschichten vor. In diesem Gelände aus Schmelztuff und Blähton begann man zu Beginn der siebziger Jahre, zwei Tunnel von jeweils 1.500 Metern Länge anzulegen. Die Bauarbeiten standen unter dem Einfluss von Dehnungs- und Dekompressionserscheinungen. Der folgende Text enthält eine Darstellung der aufgetretenen Probleme, der durchgeführten Feld- und Laborstudien und der numerischen Optimierung der Tunnelauskleidung. RESUME: Dans le sud de l’Ille du Gran Canaria (Espagne) on a détecté des couches d’argile gonflante dans l’intérieur des formations de roches volcaniques fonolitiques, à la profondeur autom des 500 m, avec épaisseur de 1 à 3 m. On a perforé deux tunnels (de longueur 1.500 m chaque un) dans cettes zones (igniumbrités et argiles gonflantes), chantier qui comenza pendant les 70’. La construction on a influencé pour des phénomènes d’expansivité et de décompression. Dans cette communication on présente les problèmes presentes, les études de chantier et théoriques realicés et l’optimisation numérique développé pour dimensionner le revêtement.

Jan 1, 2003

By Matsuo T, Uga Y

The tunnelling work to construct a sewage trunk line designed by the Sewage Bureau of Kobe City along north side slope of Rokko mountain range incorporated an all ground condition type (broad spectrum) TBM with slurry transport system with jet pump manufactured by Kawasaki Heavy Industries, Ltd. Boring dia. of the tunnel measured to 2.0 m. The construction planning and implemen- tation were done by Ohbayashi Corporation, the general contractor. The heading way was 3342.4 m in overall length.; construction work ran from April '84 to June '85. The max. daily progress marked 31.9 m and the max. monthly progress 493.1 m according to the relevant record. The machine proceeded with the work under geological conditions featured with conglomerate, rhyolite, tuff breccia and slate, whereby soft soil zone mostly of clay was encountered in a limited area. In the latter case, however, steel segments were substituted for supporting steel ribs. The tunnel was routed beneath a meandering road with the result that more than 40% of overall length show a curvature of 50 to 200 m radius.

Jan 1, 1987

By D. Bahrami, G. Danko, W. Asante

"It is prudent to interpret atmospheric monitoring signals in real-time for checking the safe limits of the air conditions in underground mines. In gassy mines, such real-time evaluation increases the safety of operation. In all mines, the continuous monitoring and evaluation contribute to maintaining air conditions to be within healthy and safe limits. Signal interpretation for safety conditions in mines is difficult for many reasons. An increase of hazardous contaminant concentrations can be predicted by signal pattern recognition, root-cause analysis of rapid changes toward deterioration and forward prediction in time using algorithms and numerical models. This paper focuses on analyzing signal patterns to recognize dangerous trends as well as forward predicting the various environmental and working conditions that may affect safety in underground mines. Efficient numerical ventilation model with heat and gas contaminant simulation components is needed for the analysis of real-time atmospheric monitoring data. Computational speed enhancement methods are discussed and tested in numerical examples, using the Jacobian sensitivity matrices for signal propagation prediction. INTRODUCTION The focus area of this paper is mine safety, related to hazardous atmospheric conditions in a mine ventilation system. Improvements by recognizing safety hazards caused by heat of combustible gases or the accumulation of poisonous gases in a mine are addressed. The recognition of safety hazard by manual evaluation is difficult because of the complex nature of information and the large amount of monitored data from measurement by atmospheric sensors such as air velocity, pressure, hazardous gas contaminants and temperature. In order to recognize problem-causing trends, it is necessary to evaluate continuously individual measurement data from the Atmospheric Monitoring System (AMS) of the mine during their time-dependent variations. In addition, the combined effects of various signal trends need to be simultaneously interpreted in their cross-effects. It is very difficult to foresee the possible outcomes of intertwined signatures of various problems by continuous human observation. For example, a steady, continuous methane concentration measurement together with a sharp drop in barometric pressure from the AMS sensors may be a case for worry in future time due to pressure-induced methane increase from the coal seam or the gob (Danko et al., 2013). This future increase can be predicted by a time-dependent Ventilation Air Model (VAM) and its surrogate Air Parameter Predictor Solver (APPS) model. A calibrated VAM or APPS model can indeed predict a likely methane concentration variation in future time as a function of previous and new air pressure as well as air velocity (Danko, et. al., 2013). Such a future trend, however, cannot be seen from the raw measurement data."

Jan 1, 2017