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By Lothar Baumann, Wilhelm Knickmeyer

In mechanized roadheading predominantly two methods of rock breakage are applied at present: the cutting method by means of picks and the cutting/crushing method by means of roller cutters. Both systems meanwhile reached a high degree of technical development and consequently show very few possibilities of further improvement. While application of hard-metal picks is limited by rock hardness, the roller cutters require a high specific thrust, and, accordingly, heavy carrier systems. Roller-cutter equipped tunneling machines are therefore only cost-effective in hard-coal mining if the high investments for transport and assembly are justified by a corresponding length of road to be headed. The limit for acceptable cost-effectiveness is at present a minimum heading length of approximately 3 km. In order to improve the specific cutting performance of roller cutters by activation, Bergbau-Forschung carried out a research project sponsored by the Commission of the European Communities and the provincial government of

Jan 1, 1981

By N. Graham, C. Walker

The SORD Miner is a patented mining principle being developed to exploit mineral and energy resources that current technology can not access. SORD Miner is designed to operate in underground wet, granular, continuously collapsing geological environments such as alluvial and marine deposits. It is somewhat like a cutter suction dredge and should be capable of mining its way through any fine granular material like sand or gravel, pumping the slurry back to the surface. In areas where the target layer is covered, the SORD Miner is inserted below the water table and will tunnel its way to the mineral deposits at depth. This paper describes the development, concept testing and prototype construction of the SORD Miner.

Jan 1, 2007

By John R. Marks

In April 1990, the Homestake Gold Mine embarked on a five year, $US 23 million underground drifting and drilling program to explore promising ore targets north of the current mine. This paper describes the ventilation and air-conditioning system that was installed for the 4m x 4m x 5.2 km (ultimately) drift, which is being driven at about 8m per day in 48OC (118.5 F) crystalline rock. Design parameters are described first. Differences in South African, Canadian and U.S. drift ventilation and civil tunneling techniques proved interesting. Details are then given on equipment selection, installation and performance. Costs are included. Special note is made of safety considerations for a long, dead-end drift.

Jan 1, 1991

By G. Zandt, H. R. Pratt, W. A. Hustrulid, M. Bouchon, D. E. Stephenson

PREFACE The National Waste Terminal Storage Program was initiated to conduct the research to select a site for the disposal of high level radioactive waste in deep geologic formations. As part of this program, the Savannah River Laboratory at Aiken, South Carolina, is conducting geologic research of generic applicability on the potential subsurface damage to a repository from an earthquake. Part of this study involved the collection of data on subsurface damage due to an earthquake, and another part involved the calculation of displacement fields as a result of an earthquake. Both of these studies were conducted at Terra Tek of Salt Lake City. This report is an abridged and combined version of both studies which was presented at the Rapid Excavation and Tunneling Conference in Atlanta, GA, on June 19, 1979.

Jan 1, 1979

By D. M. Cregger, J. L. Rosenblad, R. E. Ranken

The construction of a large span, high-walled underground opening in a low strength shale rock is unprecedented. The feasibility of constructing a pumped storage project with several tunnels and a large underground powerhouse in low strength shale rested largely on the feasibility of building stable openings large enough to accommodate the required equipment. Because of the lack of experience with large openings in shale, the decision was made to excavate a test adit and test chamber and conduct a multi-faceted geotechnical evaluation program designed to yield pertinent in-situ data on the ability of the shale to accommodate a large underground opening. Factors considered in the shape, size, orientation, and location of the test chamber were: (1) similarity to the anticipated powerhouse chamber, (2) nature of the most important data to be obtained, (3) feasibility of construction, and (4) economics.

Jan 1, 1983

By David C. McLean, Peter Penner, Martin de G. Salter

The Rogers Pass Project for C.P. Rail includes a 14.7 km tunnel and an 8.5m diameter concrete lined ventilation shaft to a depth of about 335m. The shaft collar is in bouldered water bearing glacial till to a depth of about 95m. Initial excavation in the overburden was with the aid of dewatering wells. When ground support problems arose the excavation was completed by a two stage freeze programme. Freeze holes were drilled from the shaft bottom. This most unusual method was successful in overcoming the difficulties safely and efficiently. The remainder of the shaft was sunk and lined conventionally. Finally, a central dividing wall was poured by jump forming from the bottom up. The wall was completed to a high standard at up to about 20 vertical metres per day.

Jan 1, 1989

By H. J. Handewith, W. D. Coski

This paper describes the development and testing of the RAMEX excavation system. Incorporating a synergy of low velocity, high energy impact and kerf cutting, this machine offers a competitive alternative to drilling and blasting in hard rock. It is a boom mining machine that incorporates the features of a lightweight roadheader and it can mine nearly any shape opening in hard rock. The RAMEX Tunneler has been developed to satisfy industry demands for a non-explosive, flexible, continuous and rapid underground rock excavation system. It will produce minimum ground vibration in the urban environment and allow the flexibility necessary for thin seam mining conditions. It will also reduce initial ground support costs and has a minimum impact on rock integrity. Developed by RAMEX Systems with cooperative research provided by the U.S. Bureau of Mines, this system, could produce the next step in the continuing evolution of mechanical mining systems.

Jan 1, 1989

By Francis Otuonye

Rock fragmentation by blasting still remains the most common and cost-effective method of excavating hard rock in mining and tunneling operations. During blasting, the dynamic stresses induced by the detonation of the explosive, in addition to fragmenting the rock in the vicinity of the blast, may fracture the rock at considerable distances from the point of detonation of the explosive. The fractures can result in reduced mine safety, increased costs to support the opening, low productivity and perhaps high ore dilution. Besides the dynamic stresses produced in the rock, air blast overpressure pulses are generated and propagate through the network of underground mine openings. The waves, unable to spread out spherically or hemispherically like blast waves from surface blasting, are forced to propagate by reflection from the roof, ribs and floor down the drift. Blast wave focusing can occur and produce intense shock waves that could damage ventilation barriers such as cement block stoppings.

Jan 1, 1992

By Clifton W. Livingston

So many factors influence blasting results that theories and rules are usually dismissed as impractical; the practice prevailing today is arrived at by cut and try. Usually the first step is to experiment with drillhole patterns and spacing until an arrangement is found that gives best results. The next step is to experiment with different types of explosives and sequences of blasting until the most satisfactory degree of fragmentation is achieved and until no further reduction in cost is immediately apparent. Improved fragmentation is generally attributed to the type of powder used, the sequence in which the holes are blasted, or the use of millisecond delays. Various types of drill rounds have been evolved in tunneling operations, underground development headings, and stoping, and various patterns of blasting in open pit mines and quarries. These practices usually are carried from mine to mine or from district to district, and great skill is exercised by those experienced in the art of blasting.

Jan 1, 1960

Preceding the regular meeting, "Harvest from the Sky" was shown, an action-packed movie demonstrating how man and machines provide Denver with water. This vividly colored picture illustrated the magnitude of the job, highlighting the construction scenes at the 23-mile Harold D. Roberts tunnel, many scenes of which were taken underground at the face. Presiding was Mr. John Peperakis, Alanager, Sunnyside Operations, Kaiser Steel Corporation, Sunnyside, Utah, who called the regular meeting to order at 9:30. Mr. Peperakis introduced Mr. Otto A. Wiesley, Chairman, Industrial Commission and Utah Labor Relations Board, Salt Lake City, Utah, who spoke on "Functions and Policies of the Industrial Commission of the State of Utah." It was with obvious pride that he discussed the Medical Panel in use and the successful operation of the Indus- trial Commission in Utah, stressing the fact that the most important word in their vocabulary was "cooperation." (The text of his address appears later in these proceedings; see index for page number.)

Jan 1, 1959

By J. C. F. Randolph

This mill being now in successful work, it seems proper to record some professional memoranda concerning it. It is intended to handle an unusual ore, in a locality difficult of access, and its arrangement and method of procedure present some novel features of interest. It was prepared for the San Miguel property at Batopilas, State of Chihuahua, Mexico, owned by the Consolidated Batopilas Silver Mining Company of New York, at present under the management of ex-Governor Alexander R. Shepherd. This property contains a large series of more or less parallel veins, worked through a deep cross-cut tunnel 1300 feet in length. The vein rock of these veins is calcapar in diorite. While, near the stirface, ruby silver, black

Jan 1, 1882

By John C. F. Randolph

THIS mill being now in successful work, it seems proper to record some professional memoranda concerning it. It is intended to handle an unusual ore, in a locality difficult of access, and its arrangement and method of procedure present some novel features of interest. It was prepared for the San Miguel property at Batopilas, State of Chihuahua, Mexico, owned by the Consolidated Batopilas Silver Mining Company of New York, at present under the management of ex-Governor Alexander R. Shepherd. This property contains a large series of more or less parallel veins, worked through a deep cross-cut tunnel 1300 feet in length. The vein rock of these veins is calespar in diorite. While, near the surface, ruby silver, black

Jan 1, 1882

By Maynard O. Serbousek, Melvin E. Poad

Shotcrete, a useful support material in underground openings, is a sprayed concrete, and, when used with fast-setting agents, is immediately self-supporting. Although shotcrete has been used extensively for tunnel support, the technique has not been readily accepted by the mining industry because of the lack of essential information on such basic items as material properties and rock interaction. The Spokane Mining Research Center (SMRC) of the Bureau of Mines has been active in the field for the past 2 years, including research on fibrous reinforced shotcrete. IIT Research Institute, Chicago, under Bureau of Mines contract, is investigating physical properties of shotcrete as affected by (1) type of process (wet or dry) and (2) fast-set agents and controlle-dset cements. Already the contractor has shown the advantage of a regulated-set cement over normal cement and fast-set additives for the dry process. The regulated-set cements can produce high early strengths with no decrease in ultimate strength.

Jan 1, 1997

By J. L. Humphrey

The origin of roof bolting is obscure, but is believed to have begun some 40 years ago in the mines of St. Joseph Lead Co. in southern Missouri. It was not until after World War II, and more particularly after 1949, as a result of the concentrated effort of the USBM, that roof bolting attracted widespread interest. It is estimated that at the end of 1954, 26 pct of all bituminous coal mining in the U. S. was being done under roof bolts. Those mines alone use nearly 2,000,000 roof bolts per month, according to USBM statistics. Uses in metal mines are increasing rapidly, as confidence and knowledge grow. The application has found equal success in other fields, such as tunneling work for dam and waterway construction and right of way maintenance on highways and railroads.

May 1, 1956

By Y. Ooishi, Y. Matsumoto, T. Arai, H. Ohta

The multi-circular face shield (MFS) is a new type of tunnelling machine for construction of the special cross section and has been put to practical use in 1988. The MF shield has two circular faces partially overlapped in a single shield machine and can construct the cross section shaped like glasses for the double track railway. And it is possible to equip two or more cicular faces horizontally or vertically, if necessary. During the development of the MF shield the experiments have been carried out for the purpose of estimating the excavatability and the face stability of the MF shield. As a result it was confirmed that the both types of MF shield (one with double faces aligned horizontally and the other with double faces aligned vertically) has higher performance in the face stability and lower value in the cutter torque and the total thrust than the conventional circular shield.

Jan 1, 1991

By Jin Kim, Jerry C. Tien

Water is still the most economical and popular means of controlling dust underground. It is a process that captures dust by bringing water droplets into intimate contact with coal particles. Wetting agents, also known as surfactants, can be added to greatly facilitate such a process since they tend to reduce the interfacial tension between the coal particles (usually hydrophobic) and the liquid. The surfactants used in the study were first chosen on the basis of their HLB (Hydrophile-Lipophile Balance) value, and later tested in order to select the right type and amount of surfactants to give the best performance. Both static and dynamic tests were later conducted using different types of surfactants to examine their respective wetting effectiveness on coal particles. Experimental results show close correlation with the theoretically calculated collection efficiency that is based on a horizontal tunnel and a solid-cone water spray.

Jan 1, 1993

By Thomas E. Ricketts

An important part of underground mine planning and operations involves the reclamation of working areas after blasting before the mining cycle can continue. This is especially true for mining that must use large blasting operations in the vicinity of extensive underground workings. In an effort to develop a rational procedure for estimating mine damage produced by blasting, underground rock fall has been assessed for a large-scale blasting operation in oil shale. The amount of mine damage has been quantified in terms of manshifts of effort required to reclaim underground working areas after blasting. This has been further broken down into the three main phases of reclamation, i.e., scaling and excavation, rockbolting, and miscellaneous repairs on ventilation, utilities, etc. Different types of openings have also been assessed including level tunnels, incline drifts and rooms. The effect of repeated blasting on mine damage has also been documented with initial blasts producing more damage than subsequent blasts.

Jan 1, 1988

By C. J. Pritchard

I commend the authors on examining an interesting method of shaft lining and attempting to improve safety in a dangerous environment by remotely installing the shaft lining. It is important, though, to not trade off shaft lining safety for long-term mine safety by lining an intake shaft with combustible material. In many operations, the mine utilities are installed next to the lining of the intake shaft, supplying a possible ignition source if damaged or overloaded. Although the polyurethane studied in the paper is of relatively high density, no mention is made of the flame retardency of the samples. When exposed to heat, small amounts of polyure¬thane will melt and bum but are extinguished when the heat source is removed. If large surface areas of combustible polyurethane - a tunnel or mine shaft - are exposed to ignition heat sources that are not removed or extinguished early, an uncontrollable, fuel rich fire may result with high carbon monoxide levels, low oxygen concentrations, and greatly increased burning rates that can have devastating effects on the ventilation system and miners' safety.

Jan 1, 1990

Since the 1950's drilling has been rapidly mechanised. First from hand held drills with air legs to pneumatic jumbos, then to more effective hydraulic jumbos. Development of underground drilling equipment naturally could not have stopped here. Hydraulic drilling saw an improvement in drilling capacity and efficiency after the introduction of second generation drifters in the early 1980's. Also in the early 1980's a few equipment suppliers started to study how to improve the efficiency in operating the rigs. The first computerised rigs for tunnelling were delivered to work sites in mid 1980's. At the same time a few computerised longhole drills started drilling in mines.

Jan 1, 1988

By Yokozawa K, Yamamoto T, Kameoka Y

Japan Construction Method and Machinery Research Institute has been conducting various field surveys of tunnel works and other excavation works, and the cost and efficiency of these two excavation methods have been studied. Based on these data, the costs of blasting excavation and mechanical excavation represented by roadheaders were calculated. The costs were calculated and compared for rocks of various hardness. When the total construction cost is considered, the degree of overbreak becomes one of the most influencial factors, because the overbreak area must be filled up with expensive shotcrete in NATM. So, in the next step, the relation between the excavation costs considering overbreak and the rock hardness was studied using the data on overbreak obtained by the field survey.

Jan 1, 1987