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By A. A. Mathews

During the past year (1967-68), there have been many instances of either partial or complete failure of a tunnel-support system. It looks like the art is in a pretty sad state, but as long as we permit the field of tunnel design to remain basically an art, that's about what we can expect. The application of scientific principles to tunnel design involves much more than assigning values to a series of factors in an equation. I am reminded of the case where the engineer calculated that steel ribs with struts were required to support a horseshoe-shaped tunnel in firm ground. The contractor had driven several hundred feet without installing the struts when the engineer visited the job. When he was informed that the struts had been left out, he fled the tunnel in alarm. As one authority has so aptly put it, "There is far too much calculating and too little observing." Initially, one might think of a tunnel support as a structural member, such as a strut or arch which is installed in order to support some definite load. Similarly, a tunnel lining might be considered as a treatment of the interior surface of the tunnel in order to produce desired aesthetic, hydraulic, or architectural results, or to serve a protective function. Actually, many linings, such as a concrete lining, serve a dual purpose and support a load as well as satisfy other requirements. Not too many years ago a tunnel, during the driving or excavating stage, was considered to be either supported or unsupported. In recent years, however, several techniques have been developed, which by helping the tunnel to support itself, permit the elimination of separate structural support. Since these techniques in many cases actually become a substitute for the conventional types of supports and linings, a state-of-the-art review would hardly be complete without including them for consideration. Thus, for the purpose of this discussion, we shall define tunnel supports as any system or technique which effectively maintains the integrity of the tunnel opening. In their chapters, both Jacobs (No. 6) and Lippold (No. 7) pointed out how support systems have advanced from timber supports to steel supports

Jan 1, 1970

By John E. Young

United States Steel Corporation's Winifrede Mine is operated by Lynch District in the mountainous region of Eastern Kentucky. This region is characterized by narrow mountain ridges and precipitous slows which present both an opportunity and challenge in the design and selection of coal handling facilities for the movement of coal from the section belts to the railroad cars. The narrow finger ridges precluded use of underground haulage and, thereby, presented the opportunity to use high capacity equipment on the outside bench. The precipitous mountain slopes, steepest at the Winifrede seam horizon, presented a challenge to select a solution for lowering the coal approximately 1000 feet from the seam level to the valley floor railroad load-out point. It was evident from the start of planning that these two factors predominated; namely, rail haulage and coal lowering, and solutions to these would determine the final design of the Winifrede Mine coal handling facilities.

Jan 1, 1970

By R. C. Stevens

INTRODUCTION Idarado Mining Company, a subsidiary of Newrnont Mining Corporation, is situated high in the San Juan Mountains in southwestern Colorado. Portals, offices and surface plants are located near the towns of Ouray and Telluride at elevations ranging from 9,000 to 12,000 feet. The Ouray portion of the development was initiated in 1943. Upon completion in 1945 of a 250-ton mill, processing of development ores containing copper, lead and zinc was undertaken; thus, serving as a pilot testing unit for larger scale milling operations. These facilities were subsequently enlarged and utilized until 1956. Meanwhile, in 1953 Idarado had acquired The Telluride Mines Company, 62 miles distant by highway; however, only six miles via a network of tunnels which eventually linked the two workings. Extensive underground development and increased ore production necessitated reconstruction and expansion of the milling plant. The facility was designed to accomodate processing of 1700 tons of ore daily. This goal was achieved and it represents the current daily output. MINERALOGY The veins are a compound fissure which have undergone several stages of mineralization. The first stage is represented by complex ores of copper, lead and zinc in a quartz gangue. Precious

Jan 1, 1970

Factual data about the sedimentation in the Newcastle Coal Measures are presented. Data concerning the total coal measure sequence (isopachs, sand/shale ratio, and total coal thickness variation), data about three coal seams (Borehole, Dudley, and Victoria Tunnel) and data about interseam conglomerate units are discussed.From this data conclusions are drawn about the coal measure environment. The western edge of the coal basin, the Lochinvar Dome, although a high feature, was apparently stable during coal measure time. Despite its height it apparently supplied little sediment to the basin.The northern and north-eastern edge, which was unstable, supplied most of the coarse detritus (including the conglomerates) to the basin. The conglomerates show patterns of fluvial origin but after a period of "normal" variations in pattern they become restricted to two parallel zones evidently tectonically controlled. Deposition of conglomerates is episodic and separated by periods of coal formation when deformation was apparently slight. Formation of each of the three seams considered followed a rather similar pattern- each show development of thick coal around the basin edge and poor thin coal in the "axial" region of the present synclinal structure.Evidence of ill situ formation of some areas of the seams is discussed and periodic deformation of the basin during coal measure time is postulated.The unusual character of this coal basin, in particular the very coarse units, is stressed, despite the presence of many "normal "coal basin features.

Jan 1, 1970

By C. J. Delisio

The basic concept of tunnel boring has not changed since the late 1800's. R. Stanley of Great Britain obtained a Canadian patent as early as December 1891. Mr. Stanley's machine was a device that consisted of a rotating wheel equipped with drag-type teeth; it had a means of thrusting the cutterhead against the face or heading; it had a means of clamping or gripping the machine in its bore; it had a means of collecting and depositing the cuttings into a screw-type conveyor located near the invert of the tunnel. It even had a means of varying the speed of the forward motion of the machine to suit different hardnesses of rock encountered. This description essentially fits the latest tunnel-boring machines being built today. In short, there has been no significant advance in the basic concept in 70 to 80 years. It may well be that no significant change can be expected for some time into the future. Today's machines, while still basic in concept, offer many advances aimed at faster tunneling. Among these are 1 ) improved cutters, 2) guidance and steering devices, 3) dust-control devices, and 4) mechanisms to aid in installing tunnel supports. CUTTERS The most important part of a hard-rock tunnel borer is the cutter. If the cutter can cut the rock, it is a boring machine. If the cutter cannot cut the rock, no other part of the machine can. When Jarva, Inc. decided to build a machine, the first problem was to find a good cutter. In our search, we looked at most of the cutters on the market. We selected Reed Drilling Tools' cutter because the design of their cutter was aimed at hard-rock tunneling. We feel that they build the best cutter available and provide the best possible service to their customers. As tunnel-boring machine design advanced, the transition from drag bits to roller bits was natural because harder formations required a roller bit, and it is the goal of all mole users to bore harder formations. Roller bits

Jan 1, 1970

By W. C. Schafer

In tunneling or mining where hydraulic shields, moles, or rock boring equipment is used lasers such as those shown guide the production machine by providing a continuous and visible line and grade reference. In this application the laser may be mounted in the heading, preferably somewhere above spring line. If we view the circular heading as a compass in the vertical plane with 0º referencing at the crown of the heading and 180º on the invert, then it might be said that the laser may be mounted anywhere from 270º through 0º to 90º. The laser is generally mounted 2 to 3 ft off the wall or the crown of the heading by means of a bracket that may be attached directly to the liner plate. In cases where no liner plate is used, then brackets may be bolted directly into the ribs, or grouted directly into the rock. Once the laser is in position the beam is projected to the face. Two points must be surveyed upstream between the laser and the face which define line and grade. Targets may be suspended beneath each of these points approximately 2 to 3 ft. These targets may be circular or rectangular with a surface area which approximates 16 sq in. Each of these two targets should have a ½ to ¾ in. hole drilled directly in their center. When the laser is adjusted so that the beam passes through the holes in each of the two targets, the laser beam itself will parallel the center line of the tunnel and become a visible line and grade reference over the total beam projection.

Jan 1, 1970

By I. Spector, A. J. Smith

In 1967, BACM Industries Limited started producing walboard at Saskatchewan's first gypsum products plant, located in Saskatoon, using, as a basic raw material, gyp-sum rock supplied from the company's mine near Amaranth, Manitoba. This paper describes the geology of the Amaranth gypsum deposit, the method of mining the rock and the manufacturing facilities used to produce wall-board.

Jan 1, 1970

"In response to needs created by intensive exploration and accelerating expansion of coal mining in the Western provinces, Canadian R & D on coal is progressively widening its scope. Principal interests continue to lie in coal geology, preparation and processing, carbonization, combustion and transportation, but much active work is also in progress with respect to mine environments, mined-land reclamation, and environmental consequences of coal mining, processing and use. Long-range 'basic' research, which characterized much of the R & D pattern in the fifties and early sixties and which was often no more than an attempt to prevent total extinction of a dying industry, has been somewhat de-emphasized, except insofar as it relates to 'safe' coal storage and to coal-based carbons (which are beginning to command attention as pollution control media).In this review, recent exploration, mine development and new preparation facilities are noted, and current R & D in transportation, processing, handling, carbonization and combustion is summarized. Reference is also made to investigations bearing on non-fuel uses of coal (notably as source-materials for carbons and agrobiological products)."

Jan 1, 1970

By J. B. Scott, J. S. Nelson, G. H. Kruse, W. S. Johnson, K. L. Zerneke

The economics of pressure tunnel design emphasize the utmost utilization of the least expensive pressure-resisting material available, namely, the rock surrounding the tunnel. A major difficulty in the design is the problem of transferring internal hydraulic pressure to the rock through a tunnel lining or membrane provided to maintain watertight conditions. The lining is necessary not only to prevent water loss, but to prevent the diffusion of water at high pressure through joints and fractures beyond the confines of the tunnel, an occurrence which could ultimately affect the stability of the rock mass through which the tunnel passes. Because of its toughness and ability to bridge localized areas of weakness, steel is used for a lining material whenever high internal pressures are involved. The steel lining is coupled to the surrounding rock mass through an annular ring of concrete backfill. It is paradoxical that the steel lining, needed primarily to assure water tightness, must of necessity be incorporated into the structure as a major pressure-resisting component, not to augment the bearing capacity of the concrete and rock, but to limit the strain for the safety and preservation of the steel lining itself. With the deformation modulus of the steel so much greater than that of the rock, the liner approaches its yield strength before the load capacity of the rock can be fully mobilized. An economical determination of plate thickness for steel liners is therefore dependent upon measurement of the properties of the surround-

Jan 1, 1970

By William I. Gardner

Optimum design of a structure obviously requires a thorough knowledge of the materials to be utilized in its construction. When the structure is a tunnel, a most important element in its design and construction is the geology. As a tunnel may be many miles in length and at depths of hundreds or thousands of feet, we face a real problem to meet the needs of the designer and builder. How can we determine the properties of our construction materials in this situation? Engineering geology has had a formidable challenge to meet the requirements of conventional excavation methods; the advent of machine methods for rapid excavation compounds the requirements for more detailed and more precise geological knowledge of the tunnel site. This chapter will discuss the means now at our disposal to meet the challenge to produce the required data on the tunnel site in the preconstruction stage. Our considerations will be directed towards construction of a free-flow tunnel, primarily in fractured rock formations, without any requirements for the rock mechanics type of in-situ tests that might be made for a pressure tunnel or for a large opening for an underground power plant. In essence the investigation must determine: (1) The geologic conditions affecting the type of construction equipment and excavation method of the rock to be broken and removed. (2) The quantities of water and gas to be encountered. (3) The strength and stability of the material surrounding the bore and its need for support and lining. GEOLOGICAL FACTORS AFFECTING TUNNEL DESIGN AND CONSTRUCTION The engineer or contractor may classify the rock as either competent or incompetent or more pointedly as "good" or "bad" ground. The geologist may bestow a precise petrographic name upon the rock, such as granodiorite or indurated tuff breccia or name the formation, as Mancos shale, for

Jan 1, 1970

By George H. K. Schenck

The North American-based mining engineer needs to understand the differences that exist between mechanical mining or boring machines built on this continent and those built in Europe. The differences Ere most clearly seen when machines for large-sized openings--about 15 feet high-are considered. This report will focus on the innovations of European origin. The rock-breaking tool, drag bit, or roller cone that is efficient for a particular project is related directly to the strength of the rock involved. This strength is generally stated in reference to the rock's unconfined compressivee strength in pounds per square inch (psi) although it is well recognized that a rock's shear strength is also important. Compressive strength has been adopted because it is simple to test for and provides a convenient comparison. Table 1 relates cutter type to compressive strength and indicates the general nature of the machine innovation devel¬oped in Europe.

Jan 1, 1970

By John V. Beall

With some difficulty we framed the picture of the village on the mountain getting in the railroad bridge and tunnel at the base. It was a charming scene of red-tile roofs on a green mountain in the golden autumn sunshine with the black hole of the railroad tunnel looking like something out of the movie, "The Train." We clicked the shutter, advanced the film and started back to our rented Audi. At which point there was a hail from the other side of the railroad bridge. A man in uniform was brandishing an object in the air which looked suspiciously like a rifle. We peered around. We were the only other persons in view. He must be yelling at us. He was now closing the distance at a brisk, determined gait but was still 100 yards away. The car was handy but the road was straight, paralleling the railroad tracks for some distance. We dismissed the idea of running for it. Who knows, he might shoot. When he came up we didn't have much of a conversation because it had taken us a week to learn three words of Yugoslavian-zhiveli, long life, huhvalla, thank you, and schlivavitza, the national drink (plum brandy). None of these seemed appropriate. We got the Idea that photographs of railroad tunnels and bridges were prohibited. The guard, for such he seemed to be, took the Audi plate number, administered a last scowling reprimand and stalked off. This incident was the only one in a 15-day visit to Yugoslavia which we would have associated with "Iron Curtain restrictions."

Jan 1, 1970

By H. A. Halupka, I. A. Mozer

"At its plant in San Juan, Peru, Marcona Mining Company operates two grate pelletizing furnaces for the agglomeration of 3.5 million long tons of magnetic concentrates annually. Line One, installed in 1963, was built by Lurgi as a downdraft process furnace utilizing a furnace fan for the recuperation of hot gases from the cooling zone. This line was modified in 1966 to include both updraft drying and downdraft drying, and the original roof burners were converted to side-wall burners. Line Two, a Dravo-Lurgi furnace with an annual capacity of 2.4 million long tons, was built in 1966. This line, in contrast to the modified Lurgi furnace, employs direct recuperation of hot gases from the cooling zone and utilization of process gases from the firing zone for updraft drying.At its plant in San Juan, Peru, Marcona Mining Compa-ny operates two grate pelletizing furnaces for the agglo-meration of 3.5 million long tons of magnetic concentrates annually. Line One, installed in 1963, was built by Lurgi as a downdraft process furnace utilizing a furnace fan for the recuperation of hot gases from the cooling zone. This line was modified in 1966 to include both updraft drying and downdraft drying, and the original roof burners were converted to side-wall burners. Line Two, a Dravo-Lurgi furnace with an annual capacity of 2.4 million long tons, was built in 1966. This line, in contrast to the modified Lurgi furnace, employs direct recuperation of hot gases from the cooling zone and utilization of process gases from the firing zone for updraft drying. 5 per cent increased capacity, 30 per cent lower fuel oil consumption, and approximately 400 per cent reduction in grate bar and pallet corrosion. Firing of the pellet bed was improved by conversion from roof to side-wall burners. This modification also permitted utilization of monolithic refractory in place of pre-fired shapes, thereby improving over-all furnace availability and reducing refractory stock requirements from 154 different shapes to 18.Data are presented to compare operating performance of the Dravo-Lurgi furnace and the modified Lurgi furnace. These data show 30 per cent lower fuel oil consumption and 10 per cent higher capacity per unit grate area for the Dravo-Lurgi furnace, which also averages higher availability due to greater operating flexibility."

Jan 1, 1970

By J. M. Glass, C. D. Sholtess

We at Hughes Tool Co. are extremely proud of the quality of the hardware and techniques introduced through our efforts in tunnel-machine development and of the ready acceptance of them by manufacturers and contractors throughout the world. All of us who attended the conference and who are represented in the book, we believe, anticipate an increasing need for improved methods of underground excavation. The development of such methods will permit the further exploitation of our underground resources plus providing underground space for transportation and habitation at a rate compatible with demand. We hope that our comments, derived from the application of Hughes Tool Co.'s rotary boring experience, may provide a better understanding of the boring method as a possible avenue through which the desired improvement in underground excavation may be attained. We hope you may also become aware of some of the problems Hughes, as a pioneer developer of raise, shaft, and tunnel-boring equipment, must face prior to further major undertakings in this very interesting field. Our task is to acquaint you with the present status of the Hughes Tool Co. development program as it relates specifically to tunnel-boring machines. We feel this task can best be accomplished by a brief review of the general sequence of events leading to and constituting an equipment development program and more specifically the manner in which these events have occurred to either influence or further our boring-machine development program. The development of a machine to accomplish a certain function or series of functions is usually a very long and tedious process to which any number of individuals must contribute, perhaps over a period of centuries. Of particular irony is the fact that often those who contribute most generously do not necessarily reap the greatest immediate benefit. A marketable ma- chine will, however, result from a sequence of events such as these: 1) A problem or need is defined. 2) An idea is born to eliminate the problem.

Jan 1, 1970

By D. A. Summers, C. J. Haas, G. B. Clark, J. W. Brown

While significant advances have been made in excavation of rock, largely in improvements in drilling, blasting, loading, and haulage, conventional operations have been improved until little feasible increase in efficiency or rate of advance appears possible. Tunnel-boring machines have been developed which will excavate at rapid rates in soft to medium- hard rock. Hypervelocity impact is being intensively investigated as a possible means of cutting and breaking rock, as well as lasers, electric current, explosive drilling, high frequency vibration, etc. The current development and use of high-velocity small-diameter water jets, metallic jets, and projectiles of various materials involve ultra-high-pressure phenomena of fundamental interest. Rock disintegration by water jets has been investigated in the USSR for over a decade. Large-diameter jets of low velocity are used to mine coal, and high-velocity capillary jets will cut and break rocks under laboratory conditions. Velocity ranges for breaking and cutting are dependent upon rock and jet properties, and pulsed jets break some rocks more easily than continuous jets. Spectacular laboratory results have been reported for breakage of unconfined blocks of some types of rocks. Compressors, pressure multipliers, gas explosion chambers, and water cannons have been used to generate jets. Jet properties, such as continuity, unit pressure, total pressure, and stability have been measured. Results agree with theory, although the latter has been established only for relatively low-velocity flow. Diameter, speed of traversing, and frequency of pulsed jets affect rock response. Investigations in Britain have only recently begun consideration of harder rocks and higher velocities, although water jet cores have been found to be more continuous at lower velocities than previously believed. Lower limits of jet velocity for rock cutting were established for the rocks investigated.

Jan 1, 1970

The 1969 Lignite Symposium was held at Grand Forks, N. Dak., on May 1-2, 1969. Cosponsored by the University of North Dakota and the Department of the Interior, Bureau of Mines, the meeting was the fifth in this series. Registrants from many States and Canadian Provinces attended the meeting representing many segments of energy-oriented companies, State and Federal Government, and universities. At 2-year intervals, these symposia provide a common meeting place where recent research and developments in technology and utilization of energy resources with emphasis on solid fuels (lignite) are presented. Proceedings3 of the previous symposia including a Forum held in 1958 have been published.4

Jan 1, 1970

By T. N. Williamson

Most U.S. coal production is bituminous coal. Some 90% of current production comes from a geographical area enclosed in a circle with a 300 mile radius and its center at about Huntington, West Virginia. There are important underground coal production areas in the western parts of the United States as well. Most U.S. coal production comes from fairly level seams, many of which pitch rather uniformly only a few feet per mile. Usually there will be several overlying seams of varying thicknesses, separated by several tens of feet. Fig. 1. 1. Seams have minor local undulations but these? are small enough not to be a major consideration in a horizontal drilling research program.

Jan 1, 1970

By Fred A. Anderson, George B. Wallace, Edward J. Slebir

Auburn Dam will be a thin, double-curvature concrete arch dam about 685 ft high. With a crest length of about 4000 ft, it will be the world's longest single-arch dam. The site is located on the North Fork of the American River about 40 miles northeast of Sacramento, Calif. Construction is scheduled to get under way in 1970. In planning for the design and construction of Auburn Dam (see artist's conception), the foundation material, with its various discontinuities, is being investigated and the structural characteristics of the rock mass evaluated. The investigation and testing programs will aid in defining the pertinent geologic features and their individual and cumulative influence on the foundation. The work includes geologic surface mapping, surface trenching, core drilling, geophysics, tunneling, excavating shafts and raises, performing in-situ tests, and conducting laboratory tests on core and block samples. Competent amphibolite is the predominant material in the foundation, but significant bodies of chloritic, talcose, and metasedimentary rocks, a strongly developed jointing pattern, faults, and shear zones also affect the deformability of the rock mass. A comprehensive rock mechanics program, closely coordinated with geologic investigations as well as the engineering studies, therefore is required The rock mechanics work is a combination of many analytical studies and experimental investigations. The experimental work includes laboratory tests on core samples from holes drilled for geological studies of the entire foundation and in-situ tests performed in selected areas. The laboratory testing program evaluates the general properties of all important rock types and aids in correlating many of the key structural features encountered within the foundation. To derive maximum benefit from the field tests, they are conducted in materials which represent a

Jan 1, 1970

By Henry C. Meeves

The Bureau of Mines investigated the silver production potential of the Leadville (California) mining district, Lake County, Colo., in 1966-67. The mining history of the district, the ground conditions encountered in mining, and the mine-support methods used are reviewed. The drainage problem is discussed in detail. An initial objective was to establish the existence of potential silver resources minable by low-cost open-pit methods, particularly in the silver-bearing manganese halos surrounding the major deposits. The report concludes that under present conditions, development of the deposits in the area is not economically feasible; however, a pioneer rotary noncore drilling program demonstrated that this type of exploration is technically feasible. Potential reserves of silver and associated metals are estimated. Possible mining methods for recovery of the reserves are discussed. Future production possibilities from the various subareas of the district are analysed, considering optimum operating size. Consolidation of small individual holdings for unit operation is recommended. Type of operation, amount of rehabilitation, size and type of concentrating plants required, drainage and other mining problems, and metal price trends are discussed as they bear on economic feasibility of development.

Jan 1, 1970

By William C. Peters

The frustration encountered by exploration crews in connection with land acquisition could be graphed to show a correlation with the natural law that everything tends to become more so. Figure I shows a rather common, situation. The combinations of ingredients are almost limitless and the resulting brew is often poisonous to an exploration man. A single step, that of taking a series of deep soil samples is often delayed until some sense can be made from "floating" unpatented claims which are obscure in orientation as well as position, placer claims overlapping lode claims, location posts with empty Prince Albert cans, and claims with no apparent assessment work for ten years. Add to this some patented claims with¬out monuments, a state or federal withdrawal area which may or may not invalidate pre-existing claims, a loosely defined tunnel site, and some ranchers who understandably resent the separation of surface rights from mineral rights. The picture is familiar to exploration men. One approach to such problems is to ignore them until someone voices an objection -- but then an even more chaotic situation is likely to develop. Another practice is to stake new claims to cover all ground that is "open" at first glance and then find out if there are conflicts so that the new claims can be adjusted accordingly.

Jan 1, 1970