Search Documents

By John Rudolf

Metropolitan Washington Airport Authority is currently undertaking the first Phase of Metro?s Extension to Northern Virginia. A wide range of tunnel options was considered for the Tysons Corner segment that involves about 20,000 feet of track and four stations. After consideration of many options that involved EPBM single track tunnels, NATM tunnels and large bore tunnel concepts for the entire Tysons alignment, the design now being progressed into construction involves two 520 meter (1,700 feet) long soft ground NATM tunnels with several hundred feet of cut-and-cover construction. The paper discusses the process that led to selection of the short NATM tunnels as the most feasible of the options considered for Tysons.

Jan 1, 2008

By William Gleason

The Dulles Corridor Metrorail Project is a $3-billion project that will link Dulles International Airport with the downtown center of Washington D.C. by way of a single seat train ride. The project is mostly above ground, but it does include two short, yet complex, tunnels through the area of Tyson?s Corner. The project is being completed in two phases. The Dulles Transit Partners (DTP), led by Bechtel, was awarded the first phase, a $1.6-bil-lion phase that includes 17 km (11 miles) of track with five stations. At Tyson?s Corner, the project includes twin 730-m- (2,400-ft-) long, 6-m- (20-ft-) diameter tunnels. Bechtel is self-performing construction for the $1.6-billion design-build job. Gall Zeidler Consultants was hired by DTP as designer for the NATM tunnel portion of Phase 1, and Beton-und-Monierbau was hired as tunnel subcontractor. Tyson?s Corner is an affluent and congested area that sits 152 m (500 ft) above sea level. To get through the area, it was decided that tunnels would be the best option with the least amount of disturbance to the surrounding areas. However, with extremely shallow groundcover above some points as well as soft soil throughout, the tunnels are also the most complex aspect of Phase 1. About 213 m (700 ft) was constructed utilizing the cut-and-cover method. The remaining 518 m (1,700 ft) is being constructed using the New Austrian Tunneling Method, which integrates the principles of the behavior of rock and soil masses under load, and monitoring the performance of underground construction during construction. ?The tunnel only falls 2 m (7 ft) from one end to the other and we pass through two soil conditions, they are both soft ground,? said Dominic Cerulli, tunnel task manager for Bechtel. ?Soft ground is very tricky because you have to close the ring in a timely manner to minimize settlements at the surface. If you don?t close the ring quickly to achieve a round structure that?s good in compression, the tunnel could start necking and squatting and the ground above it will settle. We are under major roadways, so excessive settlement would be a bad thing.?

Jan 1, 2011

By William Billiet

"The Dulles Silver Line Phase II is an 11.4 mile extension of the Washington Area Metro Transit Authority’s Silver line in northern Virginia. There are three miles of elevated guideway, which are supported on 188 large diameter mono-shafts founded within the Triassic Geologic Aged Culpeper Fault Basin. Three lateral load tests were performed on fully instrumented test shafts. The challenge in developing the load testing program was how to reproduce the effects of the extremely high design loads along the test shafts, considering the limitations of the load test equipment. Development, execution, and analysis of the lateral load test program is discussed.INTRODUCTIONPlans for Dulles Silver Line Phase II include two Aerial Guideway sections on elevated track, the Main Line and Yard Leads. The Aerial Guideways are supported on mono-shafts (single, largediameter drilled shafts) socketed into rock. Lateral loads are resisted primarily through the stiffness of the shaft and the geotechnical resistance of the rock socket. The monoshafts were designed in accordance with AASHTO LRFD 2014. Based on our preliminary analyses, the production mono shafts were expected to consist of 6.5, 7.5, and 8.5 foot diameter drilled shafts with rock socket lengths varying between 8 and 34 feet (averaging 14 feet). Table 1 summarizes the maximum service load combinations for each size production shaft along the aerial guideway alignment.GEOLOGYThe project is located within the Piedmont Province, a major physiographic province on the east coast of the USA extending from Alabama to Pennsylvania. Within the Piedmont, a number of Mesozoic basins formed in rift valleys. Dulles Airport is located in the Culpeper Basin, characterized by a relatively shallow siltstone rock surface compared to the adjacent areas underlain by Piedmont crystalline rocks. The geologic stratigraphy at the load test sites generally consist of residual soils and intermediate geo-material (IGM) overlying siltstone rock. IGM is a term used by Virginia Department of Transportation (VDOT) to describe residual material as it transitions between soil and rock. For the purposes of the load test, the siltstone rock is classified as fractured rock (RQD<50), and competent rock (RQD=50). Table 2 summarizes the stratigraphy encountered at each test site."

Jan 1, 2017

By Duluth Engineers' Club, Engineers' Club of Northern Minnesota

"The history of Duluth commences with Daniel de Greysolon du Lhut, one of the explorers of the Upper Mississippi who came to the head of the lakes in the summer of 1679. Radisson and Groseillier, and Claude Allouez, a Jesuit priest, are supposed to have visited the head of the lakes, -but there is no authentic record previous to that of du Lhut.In 1792, the fur traders established a fort at Fond du Lac, fifteen miles up the St. Louis River from Lake Superior, but within the limits of the present city •of Duluth. In the early 50&apos;s, there were a few scattering settlers at Oneota and around the George Stuntz trading post on Minnesota point. In 1855-6, the settlement on Minnesota point was called Duluth, commemorating the name du Lhut, and organized as a town in 1857. The first board of trustees and town council consisted of -William Nettleton, J. B. Culver; Robert E. Jefferson, Grin W. Rice and William Old: In 1870, the city of Duluth was incorporated, and five years later a portion of the same territory was incorporated as the village of Duluth, and the two municipal corporations were still in existence on March 1, 1887, when the city and the village of Duluth were incorporated as the present city.The first saw mill in Duluth was erected in 1856-57, on the present site of the ship canal. It cut logs from a virgin forest at the upper end of Minnesota point.The first railroad was built to the head of the lakes in 1870. The charter for this road had been granted in 1861 to the Lake Superior and Mississippi Railroad Company, afterward called the St. Paul and Duluth, and which is now a part of the Northern Pacific Railroad."

Jan 1, 1920

By J. B. Mackintosh

Some months ago I received a sample of a highly crystalline product occurring in the hearth of the shaft-furnace used in smelting the roasted niccoliferous pyrrhotite at Mr. Joseph Wharton&apos;s works near the Gap Mine, Lancaster County, Pa. Mr. Wharton first observed this product in cavities in the concretions in these furnaces about the year 1870, and published a description of it in that year.* Thinking that it might show some analogy to meteoric iron, he sent the present sample to Mr. George a F. Kunz, who turned it over to me, with the request that I should analyze it at my convenience. The results do not show the expected analogy, because the sulphur in meteoric iron is combined as FeS., while in this product there is only one-sixth the necessary amount of sulphur, which, however, seems to be combined with all the metallic elements present, forming a sub-sulphide of definite composition. I am informed by Mr. Wharton that he has had for a long time the sample which I have analyzed, and that it probably is about the same age as that which he first described. It is worthy of note that the material does not show any signs of oxidation, but that the crystals preserve a brilliant metallic lustre. The first two analyses, made by Mr. J. Voigt, are those given by

Jan 1, 1888

By Theodore W. Robinson

WHEREVER the amount of work renders it practicable the plan of using permanent standard solutions, in connection with the colorimetric carbon test, affords such manifold advantages that it is to be strongly recommended. That it has not attained a wider and more general application, is mainly due to the fact that, as the method is generally employed, the difficulty attending the production of the colors, and their doubtful stability when produced, have been only too evident to those who have undertaken their composition. The old method of using standard solutions made from sugar, coffee, etc., has always been hampered by the tendency of the colors to change upon exposure to the light, and the consequent liability to serious error, unless they are closely watched. Appreciating these difficulties, while recognizing the desirability of permanent colors, Mr. Magnus Troilius, at the suggestion of Prof. F. L. Erkmann, investigated the properties of cobalt, copper and ferric chlorides, with the view of determining their efficacy in the production of standard solutions. His results, as obtained, seem to have been satisfactory, but his treatment failed to eliminate many of the objections that have rendered the use of organic colors undesirable. The

Jan 1, 1888

By W. L. Austin

The only essential difference among the three methods of collecting the precious metals from their low-grade ores by fusion is comprised in the nature of the vehicle in which those metals are concentrated. If lead- or coppper-ores are used, the processes are respectively lead- or copper-smelting; but when the sulphide of iron forms the matrix in which the gold and silver are collected, the process is known as pyritic smelting. The latter method presents rarely any advantages when lead- or copper-ores are available at rates which permit profitable treatment. Pyritic silver-smelting, defined by Percy as " the smelting of silver-ores, which are either free from lead or do not contain it in sufficient quantity to collect the silver, in conjunction with pyrites, in order to produce a regulus in which the silver may be concentrated," is not, as the name would imply, confined to ores of this metal alone, but embraces auriferous silver-ores, or even gold-ores simple. This method of collecting the precious metals from lowgrade dry ores, employed at Freiberg by Barthel Kohler in 1585, does not appear, up to the present, to have been introduced into this country on a working scale. And yet the possibility of getting rid in a single operation of all the earthy or siliceous gangue of a lowgrade ore and concentrating the precious metals in a matte without loss of lead (which includes gold and silver) by slagging, or volatilization, at the same time producing a highly siliceous slag, very nearly if not quite as clean as is usual in lead-smelting, certainly commends itself. In some parts of the country, owing to the com-

Jan 1, 1888

By Chas. A. Ashburner

The occurrence of oil- and gas-springs in the State of New York has been a fact of historical record since 1627, when the existence of the Cuba oil-spring was first recorded. The utilization of natural gas at Fredonia in 1821 attracted the attention of the public to the possibility of obtaining an illuminating gas by digging and drilling into the rocks. No active search was made, however, for oil or gas by the drilling of wells until after the discovery of commercial oil in Pennsylvania in 1859. In 1862 a well was drilled at Bradford, McKean County, Pennsylvania, but a few miles south of the New York state line, to the depth of 200 feet, in search of the oil-sand which had been found at Titusville, Oil City, and at other points in Western Pennsylvania. Immediately subsequent to this, other wells were drilled in search

Jan 1, 1888

By E. B. Harden, J. H. Harden

The practical use to which topographical models or relief-maps have been put, has within the last few years taken a wider range. They are rapidly coming into favor for other than purely scientific purposes, and their value for illustration and instruction is being more fully appreciated. Topographical maps; representing by contour-curve lines the elevations and depressions of the earth&apos;s surface, are now demanded in engineering work of nearly every description, and afford a ready means of bringing out the configuration of the country in a simple manner. A beautiful example of recent topographical mapping is seen in the seventeen sheets just issued by the Geological Survey of New Jersey. By reason of the inability of unskilled persons to understand the nature of a topographical map, it is sometimes necessary to con struct the same in relief, with the rivers, canals, railroads, etc., delin eated upon it. With the aid of such a map, problems in engineer ing science which would otherwise require expert assistance to explain them, are reduced to a simple and understandable form. Relief-maps are also of value to the geologist in working out the geological structure. To the instructor they present the most ready and efficient means of imparting clear and accurate knowledge of topography and kindred subjects. To the lawyer they are invalua ble in enabling him to bring into the court-room a representation of a part of the country with all its features accurately shown, to ex plain to the court and jury the special points about which litigation is pending and which would otherwise require long and laborious description. The application of the topographical map to business purposes is shown in a relief constructed by the writers for the Cumberland Valley Railroad Company and used by that company in the various ways of calling attention to the desirability of its route. This model is based partly on actual survey and partly on sketch topography. The horizontal scale is ,%, the vertical 1/19,200 of

Jan 1, 1888

By W. H. Adams

One of the most attractive subjects for technical writers is the gigantic industry of the manufacture of sulphuric acid. This is no doubt, natural when we take into account that it has grown in this country during the past twenty years, from a production of 60,000 tons in the year 1867, to that of nearly 450,000 tons in 1887. We may well excuse much of the literature which but repeats the same old story, as it serves to bring to the public notice, at proper intervals, the hidden resources of our land; and this constant application of essential truths will sooner or later be the means of freeing us from dependence upon the Old World for necessary chemical products. The present increase in manufacture of this acid in the United States is almost wholly from pyrites ores, which we have in unlimited quantities close at hand. The largest consumption of such acid is for treatment of other native products, petroleum, rock-phosphates, etc.; and, considering the knowledge we have gained during the past twenty years, it is safe to say that the industry is but fairly established, and the causes which have operated to place us in our present proud position are but natural incentives for a further growth and an increased consumption of the many other undiscovered or undeveloped resources of our American soi1. In one of his earlier editions Muspratt says: " It would seem that the manufacture of sulphuric acid, though as extensively carried on as any other business, yet seems to be the least understood; and the ignorance of some manufacturers appears to be only equalled by that of writers, who, in their description of the production of this acid, give figures of apparatus, and vaunt as improvements, things which have been exploded for years. It is possible to find in the works of eminent men drawings of apparatus, for the production of sulphuric acid, which never could possibly have worked one day—some, in fact, could never have worked at all."

Jan 1, 1888

By S. Frimpong, G. Galecki

Dump truck tires are often used in long-haul roads in rugged terrain, with high rolling and grade resistances. These conditions increase the ton-kilometer-per-hour (tkm/hr) or short-ton-mile-per-hour (stmph)rating of tires, leading to tread wear, cuts and complete failures. The load-bearing capacities of these tires are sometimes exceeded, with truck overloading, overstressing, heating and subsequent failures. In addition, truck tire demand far exceeds the current supply capacity, with long lead ordering time. This condition has caused severe tire shortage, and the problem is expected to be sustained in the long-term. Industry has taken extensive practical measures to prolong tire service life with significant results. However, this problem can be solved through fundamental and applied research initiatives. This paper pioneers a research effort in tire service life using multibody physics, fatigue failure modes and soil failure dynamics to develop tire-road contact force dynamics. A virtual prototype simulator of the tire-road contact, using the CAT 775E (with standard tire 24.00R35) was developed and simulated within the MSC.ADAMS/NASTRAN environments. The results show the areas of the loaded tires with maximum Von Mises, principal and shear stresses, which could result in fatigue failure, tire wear and tear and blowouts. The maximum Von Mises stresses on the six truck tires are between 35 and 58 MPa. The maximum shear stresses are also between 19 and 33 MPa. These stresses will cause early tire failures given an average operating schedule of between 20 and 24 hours per day. The isolated areas with maximum stresses will be subjected to further studies to reduce stress intensity while preserving tire performance.

Jan 1, 2012

This paper sets out to consider a specific type of corrosion protection system, which is referred to as a Duplex Coating system. The dictionary describes a duplex system as consisting of two elements or a “twofold” composition. The duplex system described in this presentation is such a two-part corrosion protection coating, viz, hot dip galvanizing as the firm base or primer, followed by a top paint system designed to combat severe corrosive environmental conditions encountered in nature. In principle, the duplex system is a cost effective and balanced, designed coating that is suited to the environmental conditions and service life requirements.

Jan 1, 2009

By G. Dhakal, J. -I. Kodama, K. Neaupane, T. Yoneda

ABSTRACT Durability tests and evaluation of sub-zero temperature effects to some argillaceous clastic rocks were carried out. Welded tuff, limestone, sandstone and schist samples collected from different parts of Japan were tested and results are presented. Schist and dolomite from Ganesh Himal area along the higher Himalayas of Nepal were also tested, and the results are compared. The slaking tests were performed on all samples in pure water. The results reveal that the slaking index of schist from Japan is lower than that of schist from Nepal. Regarding carbonate rocks, the slaking index of limestone from Japan is higher than that of dolomite from Nepal. A tendency of decrease in slake durability with an increase in porosity is also observed. Freezing and thawing experiments conducted on welded tuff and schist reveal that crack initiates earlier but extends slower in schist than in welded tuff. It is also observed from the freeze-thaw experiment that the welded tuff deteriorates and wears faster than the schist. However, sandstone remains relatively intact for a long run of freeze-thaw cycles. Zusammenfassung Beständigkeitstests sowie die Bewertung der Auswirkungen von Minusgraden auf Tonschiefer Trümmergestein wurden durchgeführt. Dabei wurden geschweißter Tuff, Kalkstein, Sandstein und Schiefer aus verschiedenen Gebieten Japans sowie Schiefer und Dolomitgestein aus dem Ganesh Himal Gebiet, dem höheren Himalaya Nepals, untersucht und die Resultate verglichen. Für alle diese Gesteine wurden Slaking-Tests in reinem Wasser vorgenommen. Die Resultate zeigen, dass das Slaking von Schiefer aus Japan höher als das von Schiefer aus Nepal war, wohingegen bei kalkhaltigem Gestein das Slaking von Kalkstein aus Japan niedriger als das von Dolomitgestein aus Nepal ausfiel. Es wurde dabei auch eine Tendenz zur Löschbeständigkeitsverringerung bei gleichzeitig erhöhter Porosität beobachtet. Gefrier- und Tautests an geschweißtem Tuff und japanischem Schiefer zeigten, dass Risse in Schiefer schneller auftraten, aber sich langsamer ausweiteten als in geschweißtem Tuff. Bei Gefrier- und Tautests wurde ebenfalls beobachtet, dass geschweißter Tuff schneller verfällt und verschleißt als Schiefer. Sandstein hingegen blieb über lange Tau- und Gefrierzyklen intakt Résumé Des tests de solidités et l’évaluation de l’effet des températures en dessous de zéro sur les rocs argileux ont été effectués. Les rocs d’origine volcanique (cendre), les rocs calcaires, sableux et les schistes de différentes régions du Japon, ont été étudiés. Les schistes et les dolomites de la région de Ganesh Himal le long du haut Himalaya (Népal) ont été étudiés et comparés à ceux du Japon. Les tests de désintégration sur les rocs ont été effectués dans l’eau pure. Les résultats montrent que l’index de désintégration des schistes du Japon est inférieur aux schistes du Népal. En ce qui concerne les rocs carbonyles, l’index de désintégration des rocs calcaires du Japon est supérieur à ceux des dolomites du Népal. Une décroissance de la résistance à la durabilité est observée avec une plus grande porosité des rocs. Les tests de congélation-décongelation sur les schistes et les rocs d’origine volcanique (cendre) du Japon montrent une apparition précoce des fissures mais l’expansion des fissures est plus rapide dans les rocs volcaniques. Des tests similaires montrent que les rocs volcaniques (cendre) se désagrégent plus rapidement que les schistes. Cependant, les rocs sableux restent intacts après plusieurs cycles de congélation-décongélation.

Jan 1, 2003

By Wern-Ping Nick Chen

Durability risks for underground facilities can be underestimated during design phase as compared to well-known geological risks. However, unclear durability requirements can result in construction schedule delay and change orders. Unlike bridges or buildings, a unified underground durability code or standard does not exist. This paper will provide a durability approach for underground facilities, including degradation modes, mitigations, and compliance measures during construction. In addition, this paper will address how to clearly specify durability requirements in a contract document to reduce disputes during construction and discuss key durability tests that are time consuming and will impact construction schedule if not timely planned.

Jun 23, 2024

By D Wimpenny

Underground infrastructure is often a critical component of transportation and utility schemes. It is characterised by long design lives with limited access for inspection and maintenance. The exposure environment can be difficult to assess since it will often vary substantially between different locations in the same facility and with time during construction and in service. In addition, the specific demands placed upon underground infrastructure are not well covered by the exposure classes and other guidance given within current codes of practice. When problems occur they can be difficult to rectify and involve significant disruption.Given these substantial risks the prudent designer may adopt a systematic ‘durability planning’ approach which:· defines the environment and principal deterioration mechanisms for the various elements and construction materials,· predicts the design life for alternative durability enhancement options, and· recommends associated measures to be adopted during construction and in service.This paper describes the development of durability planning within Halcrow, giving examples of its use from its first implementation on tunnels under the Suez Canal in 1993 to recent projects in the Middle East and Australia. It seeks to demystify the process, identify shortcomings and speculate on its future development within the civil and mining sectors.

Mar 8, 2011

By Qingjun Zheng, Robert Vasinko

Cladding by plasma transferred arc (PTA) welding is widely used for enhancing the surface properties of a metallic component, in particular wear, high temperature and corrosion resistances. This paper presents the application of Kennametal Stellite PTA cladding technology, especially the DuraStell PTA process technique, for tungsten carbide composite cladding for boiler tube application. DuraStell PTA process gives low heat input to the substrate and fast deposition rate. The cladded boiler tube samples showed more uniform carbide dispersion in the cladding, less base metal dilution, and insignificant effect on the microstructure and mechanical properties of the substrate base metal, in comparison of the traditional PTA and other arc welding process.

Mar 1, 2017

By Andrew K. hg` Officer, A. L. Griffiths, J. Andrew Hindmarch, Gert Wittneben

Durban Harbour in South Africa is one of the continent’s busiest ports however the harbor entrance is currently too small for the new generation of container ships. There-fore it is to be deepened and widened by the National Ports Authority in the near future. An existing immersed tube tunnel carrying major sewer, water and other utilities under the harbor first needs to be removed and replaced by a deeper 4.4 m ID ser-vices tunnel. Construction of the deeper tunnel saw the first use of a slurry machine in South Africa and was required to negotiate grades up to 20%.

Jan 1, 2007

By R. R. Godard

The practice of dust abatement or control is not new to any operation of United States Steel Corporation. This report will review those activities, past and present, within the five operating districts of United States Steel-Coal Operations with specific reference to mechanical and continuous mining, and including both the health and safety aspects of the problem. Obviously, the first principle of dust control is to inhibit its formation If this is not practical, steps may be taken to prevent its becoming airborne. Airborne dust control can be realized by either collecting it at the point of generation, diluting it with large volumes of air to reduce concentration, settling it by various means, or with reference to ignition hazard only, render it incombustible by neutralization with an inert material. These basic principles have been verified by the work of many, including the Bureau of Mines, U. S. Department of Interior, Bituminous Coal Research, Inc., and the Mining Research Establishment of the National Coal Board of Great Britain. Their application to every day mining problems is best illustrated by the following examples.

Jan 1, 1967

By N LaBranche

The resurgence of Silicosis and Coal Worker’s Pneumoconiosis (CWP) in coalmines has placed the spotlight back on the management of worker exposure to particulate matter across all mining sectors (Coal Workers Pneumoconiosis Select Committee, 2017). There already exists a substantial body of knowledge on particulate matter and its impacts upon human health (National Academies of Sciences, Engineering, and Medicine, 2018). The contribution of silica to respiratory disease is well known and there is a growing concern for exposure to diesel particulate matter. However, it is also clear that there are major gaps in our understanding. In part, those gaps relate to the contribution to adverse health effects of mineralogical constituents in the dust (LaBranche et al, 2021a). It is also becoming evident that the size and shape of the particulate matter can affect its potential impact on human health.The University of Queensland has developed a methodology for characterising respirable and inhalable dust samples using scanning electron microscopy. Multiple samples from numerous mining operations have already been analysed using the UQ methodology. The process has been successful in showing the variety of mineralogica lcomponents and particle size distributions presentin various areas of the mines.

Oct 12, 2022

By J. Seiter

Mining has always been among the most hazardous of occupations, and with the increasing demand for coal and minerals, safety in mines assumes even greater importance. Worldwide, underground miners are being exposed to noise and respirable dust hazards associated with roof bolt drilling. These hazards are now being understood to cause irreparable damage to the health of miners. The objective of this research was to discover if a Polycrystalline Diamond Cutter (PDC) drill bit generates less respirable dust and hazardous noise than a competing Tungsten Carbide (WC) bit, in dry vacuum drilling. In order to control the drill parameters the drilling tests have been conducted in a laboratory setting. The results were met by determining the quantities of dust and noise generated using each drill bit and analyzing those levels by using monitoring devices and software to collect the data. This paper includes information on experiment setup, equipment used, drilling parameters, and data collected. The test results suggest that there are noticeable trends that the PDC bits produce less dust than WC bits but more testing is needed to substantiate these trends.

Feb 23, 2014