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By Roger J. Morrell

Disk-cutter experiments were performed on five rock types ranging in compressive strength from 9,000 psi to 27,000 psi. A specially constructed testing machine called a linear-cutter apparatus (LCA) was designed to load and traverse a free-rolling disk cutter across a sawed rock surface. The LCA was instrumented to measure the vertical and horizontal forces acting on the cutter during the run.. The ability of disk cutters to fragment rock was determined for both 60--degree and 90-degree cutting-edge angles, and relationships and regression equations were developed to predict cutter performance based on rock physical properties and applied forces,

Jan 1, 1970

By E. Kurt

The field of percussion rock drilling is subdivided into two areas of application; that which takes place on the surface and that which takes place underground. Surface drills are used in quarrying, highway construction, and maintenance work; underground equipment in mining and tunneling work. Two basic principles are involved in the operation of all percussion drills. First, the principle that reciprocates the impacting piston and second, the principle that causes the drill steel and bit to rotate. The back and forth motion of the piston is accomplished by a self-acting automatic valve that admits air alternately to each end of the piston (Figure 1). Drill steel and bit rotation is imparted by an integral ratchet mechanism (Figure 2) in the so-called "rifle bar" machines (Figure 1) or by a separate pneumatic motor in "independent rotation" drills (Figure 3). While rock drills are subject to all kinds of physical and operational abuse, they are most sensitive to faulty lubrication. Proper lubrication is the single most important factor in the longevity of a percussion drill.

Jan 1, 1970

By E. G. Beinlich

The continuing search for faster, safer, and more economical methods of excavating underground openings has led the staff of the Mather mine of the Negaunee Mine Co. directly to mechanical boring of raises and drifts. The mine is located within the city limits of Negaunee and Ishperning in the eastern portion of the Marquette Iron Range in the Upper Peninsula of Michigan. It is owned jointly by McLouth Steel Corp., Bethlehem Steel Corp., Republic Steel Corp., and The Cleveland-Cliffs Iron Co., who also serves as the operating agent. A total of 2,400,000 tons of iron ore averaging over 60% Fe is mined annually by the block-caving method. This provides feed for the Pioneer pellet plant at Eagle Mills where 1,450,000 tons of pellets are produced yearly with the remaining tonnage being sold as coarse ore. Technical staff of Cleveland-Cliffs have long realized that improved methods of advancing raises and drifts were a necessity if underground mining of iron ore was to survive the transition period in the steel industry's requirements from direct-shipping ore to pelletized ores. For this reason, the Mather mine embarked upon an experimental raise-boring program with a prototype machine in 1961. Improvements since that time in equipment and practice have resulted in the acceptance of mechanical boring of raises as a standard development tool and a vital link in the fulfillment of an orderly development schedule. Advancement of large-diameter openings such as main-level drift headings by mechanical methods in the harder, more competent types of rock has developed more slowly in the mining industry due to the need for more compact and portable machinery and improved bit technology. Many of the obstacles have been overcome by the manufacturers, and in March 1967 it was decided to proceed with a program to bore approximately 4000 ft of 13-ft-diam drift in the Mather graywacke footwall rock.

Jan 1, 1970

"The outlook for Eastern Canada is decreased coal production and for Western Canada increased production. The market for Western coal is expected to reach 40 million tons per year in metallurgical and thermal-power markets.Technical developments in Eastern Canada include successful methane drainage experiments, modifications to the shearer-loader to improve cutting rates, mechanized mining of a tail-gate stable and mechanical stowage of level brushing. In Western Canada, the most modern equipment is used in mining, beneficiating and shipping coal. Underground hydraulic experiments were started in 1969. The importance of reclamation was recognized and plans have been made to re-vegetate disturbed areas and mine dumps.The Mining Research Centre closed the field office in Nova Scotia and is preparing to open a new field office in Calgary, Alberta."

Jan 1, 1970

By Richard J. Robbins

This paper is presented with particular reference to the findings of the OECD Advisory Conference on tunneling held last July in Washington D. C. A great deal has been said about the Conference in the past few months, but it may be appropriate to review briefly the background and objectives of the Conference to better understand how the mining community can relate its underground excavation problems to the results of the Conference. OBJECTIVES OF THE OECD CONFERENCE The world demand for tunneling (the term tunneling is used here loosely to include almost all forms of underground excavation) is expected to grow at an in- creasing rate. During the decade of the ?70's, the demand is expected to at least double by comparison with the previous decade. Much of this increase in demand will be due to the rapid growth of urbanization around the world. As urban populations grow larger and denser, the conservation of surface land and the quality of the environment become more important. This aspect of the increasing demand poses a difficult challenge to those who must plan and implement urban development.

Jan 1, 1970

By Howard L. Hartman

Probably no aspect of underground excavation is as important or as neglected as the environment. The Committee on Rapid Excavation, formed by the National Academy of Engineering to study the technological needs for "rapid" underground excavation in tunnels, shafts, and mines of the future, encountered a blank wall in attempting to evaluate environmental needs. In fact, so little quantitative information on the extent of present-day hazards is available that projection of future environmental-control demands must await more adequate assessment of current hazard levels. Further, there are not even accepted tolerance standards for many environmental conditions, such as heat, noise, and illumination. Only certain atmospheric contaminants have been satisfactorily catalogued. Any technical study, therefore, which purports to examine the state-of- the-art on underground environmental control must, in reality, settle for a cursory survey of a rather nebulous subject. ENVIRONMENTAL HAZARDS To contend adequately with hazards in the underground environment requires some knowledge of their nature and characteristics. In this regard, it is helpful first to identify our concern: when, where, and to whom or what may environmental conditions constitute "hazards"? Table 1 summarizes considerations that are important in this regard. For the purposes of this Conference (and book), primarily directed toward the excavation process itself, the hazards of consequence occur during excavation (item A) and primarily within the excavation (item B). However, some attention must be given to external hazards as well, since these may affect excavation. The object of concern (item C) is mainly human safety, although property security is also important. Hazards occur in a variety of forms. If one is to devise suitable control

Jan 1, 1970

By J. Donovan Jacobs

An underground excavation project usually is a highly organized complex of different but interrelated construction activities. It is the whole effort, including the necessary tools, which will be referred to as the System. Tunnel-driving and shaft-sinking operations are among the most systematic of construction efforts. Systems are not new in the performance of construction. It is the Systems Concept which seems only recently to have been discovered and made the subject of much study and discussion. HISTORICAL From the seventeenth century, when explosives were first utilized for rock excavation, until the successful application of the rotary-head continuous tunneler in this decade, the cyclical drill-blast-muck-support method has been standard tunnel-driving procedure throughout the world. Whatever improvements occurred were the result of development of better tools for performing the various operations of the cycle. The electric locomotive replaced the mule and permitted the use of larger muck cars. The steam drill, which ended the day of the double jack, was itself quickly made obsolete when compressed air replaced steam as the source of drilling energy. Power shovels were introduced to save the time and money involved in the hand-loading of excavated materials. A cubic yard of rock tunnel muck can be excavated today for just half the man-hours of labor required in 1948. Developments over 20 years which cumulatively have resulted in this economy include: drifter drills mounted on hydraulically controlled booms and positioners; tungsten-car- bide-tipped bits; long feed shells on the drifters, making it possible to drill the full depth of a round without changing steel; better designed,

Jan 1, 1970

By G. W. Housner

The series of earthquakes in the vicinity of Koyna Dam in south- western India, which included a very damaging magnitude 6.5 shock on Dec. 11, 1967 (Dec. 10 GMT), is of much interest. The events are exceptionally well documented, which is a tribute to Indian geologists, seismologists, and engineers. To help in disseminating the information in the United States, this chapter presents a brief summary of the pertinent data and lists references. Koynanagar (Koynatown), which began as the construction camp for the dam, is located about 140 miles southeast of Bombay and 70 miles south of Poona at 17.4ºN and 73.7ºE, about 40 miles inland from the Arabian Sea. Koyna River flows almost due south from its source a distance of about 38 miles and then makes an abrupt turn to the east and travels some 480 miles to empty into the Bay of Bengal. Koyna Dam is located about 3 miles north of this turn. The approximately north-south trending continental divide is a few miles west of Koyna and the terrain drops steeply about 1700 ft to where the hydroelectric generating station is located. The reservoir behind Koyna Dam forms a long, narrow lake (Shiva- jisagar Lake) with mean water level (MWL) at 2160-ft elevation. The 345-sq-mile watershed receives an annual rainfall of about 200 in., most of which falls between mid-June and mid-October. The peak storage is 99 x l09 cu ft. A controlled flow passes under the continental divide in a tunnel and then down to the electric generating station about 5 miles WNW of the dam. The inflow not used for power generation is released to Koyna River. The Koyna project is a major source of electric power for Bombay and produces 540 MW at peak load.

Jan 1, 1970

By John F. Abel

A good mining engineer is supposed to make a good mine. What then makes a good mining engineer? There certainly are a lot of answers to that question. The answers depend on whether you are one, work for one, or employ one. There are several cliches about mining engineers, and there is some truth in them-as there usually is in any stereotype. Hollywood chose Jeff Chandler to portray a mining engineer in Foxfire. The image here was of an almost one-man mining operation. When Chandler picked up a jackhammer, cradled it in his gut and started drilling out a tunnel round, it gave one the hives. I would have liked to see him finish just one round that way. There are limits to what even the most hairy-chested of us will try. We can assume that Hollywood feels it needs to over- draw any profession to add impact.

Jan 1, 1970

By John A. Sievert

Sedimentary deposits contain an appreciable portion of the world's supply of uranium. Predictions of nuclear fuel usage in the United States indicate that these reserves will have to be tapped if the domestic industry is to be the major supplier of fuels for the nuclear reactors. Techniques developed within the petroleum industry are a base on which to build economically attractive fluid mining processes for the recovery of these uranium values. The problems central to the success of such mining processes are the containment, control, and recovery of a narrow band of pregnant leach solution as it progresses from the point of injection to the point of production Given sufficient incentive, suitable solutions to these problems can be found

Jan 1, 1970

By Thomas Adair

Moderator-Thomas Adair is now a tunnel consultant with Perini Corp., Spring Lake, N.J. He has had 40 years experience in tunnel and shaft-sinking work in both soft and hard rock, as well as subaqueous rock. He has used moles in various locations and has traveled around the world studying the problems. SOME BRIEF COMMENTS ON "MOLES" by Thomas Adair We of the Perini Corp. have been, over the past 15 years, in the forefront of the battle to develop the mechanized miner. We have contributed much to pioneer, develop, and promote the use of the mining machine. Our money and talent have not been spared in this effort. However, we are sorry to say that as of the present time (1968), at least from the economic stand- point, this effort has not been very rewarding. But, I must say to those who are presently involved in the work of building mining machines, do not be discouraged. There is money in it. We of Perini Corp. know because we put it in there. It has been estimated that during the next 15 years, some $20 billion will be spent on underground excavation; more than 13 thousand miles of sub- surface tunnels will be excavated throughout the nation. An aggressive, properly structured research and development effort would produce, within the next five or ten years, a better excavation technology and improved boring system capable of reducing present costs drastically, with a resultant great saving. The time for this effort is now, but where the enabling money for this effort will come from, I have no idea. Machine builders should be encouraged to design and develop a shield- type boring machine capable of continuous mining through varying types of ground or rock by incorporating the possibility of making minor modifications such as change of bit type, power package, etc. Such a machine could

Jan 1, 1970

By Robert Walker

The win theme of this session is Unique Material Handing Systems. The theme was selected because of two major factors. 1. Accomplishments of unique character manage to attract interest regardless of their age. 2. There is much to be learned from pioneering efforts of the past as they are the stepping stones to technological development. Thus, 2-1/2 years after completion, the engineering feat of Oroville Dam still looms large let us take a close look at this project to see what made it unique. To begin with, it established a number of firsts: At 770 feet it was the highest earth fill dam in the world. At $121 million dollars, it was the largest ever United States construction project (Civil). At 80 million cubic yards it had the largest earth volume of any dam in the world. The extensive use of belt conveyors for this application had never before been tried. The use of a high capacity bucket wheel-excavator with shiftable belt conveyors had never before been utilized as a con¬tractor's tool. The principal of the "integral train" was applied most effectively whereby up to 220,000 tons of material-was transported daily some 14 miles. To achieve optimum economics a number of technical breakthroughs were necessary. The suppliers of major commercial components worked hand-in-hand with system engineers to develop new machinery necessary for the highly mobile characteristics of the systems, viz., single pulley drives delivering 2000 horsepower, 1000 horsepower right-angle shaft-mounted reducers, across the line starting of 1000 horsepower squirrel cage motors, 10 miles of steel chord conveyor belts with belt tensions up to 150,000 pounds, aircraft-type disc brakes, hydraulic take-ups, train loading at a rate of 25,000 tons per hour, automatic train indexing for rotary dumping at 10,000 tons per hour, roll-over car dumping without uncoupling cars, shifting 7500 ft. long conveyors up to 300 feet laterally without disassembly. These are some of the superlatives that have made the Oroville Dam project unique. The measure of its success is demonstrated by the results.

Jan 1, 1970

By T. T. Gronfors

The excavation process and equipment used for excavation join firmly each other. By changing the process or method, the construction of equipment may be altered essentially. It has been possible to develop a wholy new type of hydraulic boom for tunnelling, when only parallel drilling instead of V-cut is used. The utilization of controlled blasting has made small holes more desirable. So the controlled blasting has had an influence on the selection of drill steel equipment and in this way also influenced the construction of the equipment.

Jan 1, 1970

By T. Olrog

Dissemination of technical data on developments in rock-blasting techniques in Sweden initially takes place as personal contacts and contacts between companies. In addition to these informal contacts, contacts occur in Sweden in a somewhat more organized form. There exists an informal working group--the Rock Blasting Committee--which consists of a number of personal representatives from various companies that perform rock blasting on a large scale and from firms manufacturing the equipment that is used. This means that people from both mining and construction companies get together, plus the manufacturers of explosives, drill steel, drilling machines, and loading equipment. This working group has, so far, succeeded very well in ignoring the purely commercial interests of the companies concerned. Cooperation in this form was started in the 1940's when the tungsten-carbide drill steel was invented-the group originally concentrated entirely on the development of that product. Their activities have been broadened since that time and now a meeting is held every year, at which practical experiences are reported. Only in the past five years have subjects relating to blasting procedures to avoid rock damage been treated at such meetings. This, of course, does not mean that such techniques had been neglected previously. It does, however, reflect the fact that practice in this field is still under development. Why do we try to be careful about the rock surfaces? Obviously, it is a question of economic evaluation. An even rock surface provides, in certain cases, the conditions for more favorable maintainance costs later on, greater strength, and a diminished risk of slides. The economic connections in this field, however, are neither simple or clear. A well-controlled blasted rock surface limits the need for concrete when you later build the concrete constructions. In this respect, the connections are all the more clear. In certain situations, such as tunnels for hydroeletric power plants, a good rock surface that is not lined is hydraulically more favorable than a more coarsely blasted surface. This permits a gain in the height of fall, but the

Jan 1, 1970

By E. E. Mason

The Canadian National Railway system is completing construction of the first major tunnel in North America to use the coarse-aggregate (+ ½ -in.) shotcrete technique of primary support and lining. The tunnel was driven 29 X 20 ft in cross section, 10,760 ft long, passing under an industrial and residential area of Vancouver. With the exception of 1400 ft in soil (mainly impervious tills), the tunnel passes through a very young series of flat-lying sedimentary beds, to a large extent so incompletely consolidated as to fall apart on exposure. For a conventional steel-support system, it was estimated 8 WF, 28-lb steel should be used at 5-ft centers. Cost of erection including lagging would amount to $120 per linear ft of tunnel at 304 per lb. With 8-in. concrete cover on the steel, lining would cost $280 per linear ft at $82 per cu yd. Thus, minimum cost of support and lining would have amounted to $400 per linear ft. It is now estimated that at least 90% of the rock tunnel would have required support and 100 % required lining. Specified shotcrete support was 6 in. in the arch and 4 in. in the walls. Cost of this work was roughly $100 per linear ft. In addition, another $10-$12 per ft has been incurred in drainage and waterproofing wet areas and in measures to correct experimental and operational errors, thus finalizing the support as a lining (Fig. 1). The tunnel was driven three shifts five days weekly, no blasting being allowed by city ordinance between midnight and 7.00 a.m. A six-drill jumbo was used to drill a 10-ft round, 110 holes blasted three times daily. A 2-in. layer of shotcrete was applied to the newly blasted arch commencing within 45 min of blasting. This was done from a flying deck that extended over the muck pile from the jumbo (Fig. 2). Also during the mucking cycle, the preceding incomplete arch support was brought up to 6-in. specification. The walls were sprayed 4 in. thick during the drilling cycle (Fig. 3). The shotcrete machines and aggregate bins were mounted on the jumbo.

Jan 1, 1970

By N. G. W. Cook

At present, tunnels can be driven in rock by either of two essentially different techniques, in one of which rock-breaking is accomplished by drilling and blasting and in the other by mechanical loading. The methods based on these techniques are comparable in terms of the rates at which tunnels may be advanced, although they differ widely in their range of applicability to different types of rock and lengths of tunnel. The method based on drilling and blasting has reached a high degree of development. It is applicable to even the hardest rocks and rates of advance in excess of 50 ft per day (fpd) are attainable. The main disadvantages of this method are that it involves a sequence of operations punctuated by blasting and that it is relatively uncontrolled, resulting in overbreaking the tunnel profile and damage to the surrounding rock. However, its flexibility, mobility, and low capital cost constitute real advantages in many situations, such as those involving short lengths of tunnel or low rates of advance. Tunneling machines based on mechanical breaking of the rock are a more recent development. They offer a continuous and controlled means of tunneling capable of rates of advance in excess of 100 fpd under favorable conditions. However, these machines weigh many tens of tons and consume several hundred horsepower, so that they are costly and lack mobility. At present, their applicability is limited to long tunnels in relatively soft rock where the high rates of advance and tunnel quality can offset their onerous capital cost. Many situations exist in which the superior quality of a machined tunnel and freedom from blasting would be real advantages, but where the rock is either too hard for existing machines or the length of the tunnel does not justify their capital cost: What are the possibilities of developing cheaper, more flexible, and mobile tunneling machines? Most existing tunneling machines fragment all the rock at the tunnel face to facilitate its disposal. If a machine were used to cut only the profile of a tunnel as one of a sequence of operations, it would be required to break

Jan 1, 1970

By N. K. Bohidar

Evaluation of the stability of a structure under given boundary conditions requires accurate knowledge of the state of stress as well as the mechanism of failure at the critical state of stress. This paper represents a part of the research done by N. K. Bohidar during 1965-1968 for his Ph. D. research in Mining Engineering at the University of Utah. It summarizes the determination of internal stress and failure phenomena around cylindrical openings in viscoelastic media subjected to lateral restraint and vertical uniaxial load. The conditions of lateral restraint and viscoelastic nature of the media represent conditions associated with subsurface openings in rocks. The financial assistance provided to the project from the University of Utah Research (Uniform School Fund), W. C. Browning Scholarship Fund, Earth Science Research Fund, and D. C. Jackling Loan and Scholarship Fund is gratefully acknowledged. The authors also acknowledge the assistance of S. Siugh, W. Jones, and K. McCarter during the project.

Jan 1, 1970

By R. R. French

The industrial minerals industry in the Atlanta, Ga., area was studied in order to better understand problems associated with exploiting mineral resources in and near metropolitan areas. A method for delineating the Atlanta urban area and its component parts was developed so that the factors affecting the location of the minerals industry could be viewed mere objectively in the urban context. Major attention is focused on the area's dominant crushed stone subindustry Demographic and socioeconomic analysis of the Atlanta, Ga., area shows that expansion of the metropolis and its environs will probably eliminate potential mineral resources from the mineral resource base in the area, and that the expanding metropolis will be the primary determinant of future mining sites. Competition for land is accentuated to varying degrees by the incompatibility of wining operations with residential and other environmental requirements. Areas of consideration are suggested to provide maximum development of land and resources for greatest economic benefits it minimum social cost. Further research is recommended to determine market locations in urban areas, optimum operating levels for industrial minerals plants, and alternatives to surface mining.

Jan 1, 1970

By J. O. Wheeler

"DEFINITION OF THE REGION, ITS BOUNDARIES, AND PHYSICAL AND GE'OLOGICAL CHARACTERISTICSTHIS PAPER concerns the Western Cordilleran region, embracing most of British Columbia, the southern half of Yukon Territory and the southwesternmost part of the District of MacKenzie. It excludes Vancouver Island and the Queen Charlotte Islands, which are discussed in a background paper on the Pacific Continental Shelf. The region is bounded on the south by the northwestern United States, on the west by the continental shelf and Alaska, on the north by the front of the Ogilvie Mountains, on the northeast by the axis of the MacKenzie Mountains and on the east by the Rocky Mountain Trench.The region is dominated by two mountain chains that con tain icefields and glaciers: the St. Elias, Coast and Cascade Mountains in the west; the Selwyn, Pelly, Cassiar, Omineca and Columbia Mountains in the east. The Intermontane region between these mountain chains consists of lower mountains and plateaus. In the mountains, the region above the timberline and many of the steep valley-walls provide good exposures of rock, but these areas are subject to rockslides and landslides and in winter to snow avalanches. Much of the Western Cordillera was covered by ice-sheets at various times during the Pleistocene epoch. Consequently, the larger valleys in the mountains and much of the Intermontane region contain much glacial drift and alluvium and only limited exposures of rock. This same terrain in the Southern Cordillera, however, is the most favourable for agriculture. Parts of the region, particularly in the two mountain chains, are heavily forested. Elsewhere, the forest cover is less, with grassland prevailing in the south and tundra in the north."

Jan 1, 1970

By Akira Yokoyama

Japan is composed of four main islands: Honshu, Hokkaido, Kyushu, and Shikoku (Fig. 1). Between Honshu and Kyushu, a railway tunnel and a road tunnel have been open since 1942 and 1958, respectively. Hokkaido, [ ]

Jan 1, 1970