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By Jan M. Mutmansky

While production scheduling for both surface and underground mining operations is similar in nature, a rather large array of techniques is applied in solving such planning problems. The techniques consist of both rigid operations research (OR) methods and practical procedures which are not mathematically based. In the following sections, a short summary of some of the techniques that are applicable to production scheduling problems in mineral operations is presented. The techniques discussed are: linear programming, integer programming, dynamic programming, graph and network theory, simulation, and heuristic methods. For an in-depth comprehension of these techniques, the reader is referred to any of the available textbooks on these subjects. One or more references will be listed for each topic to provide a starting point.

Jan 1, 1979

By Glenn A. Gruber

The conditioning of phosphate flotation feed with anionic flotation reagents was identified as a high- priority research topic during a beneficiation work- shop sponsored by the Florida Institute of Phosphate Research (FIPR). FIPR subsequently solicited research proposals to identify the mechanisms of reagent adsorption, to determine scale-up relationships for conditioner design, and to investigate the effect of conditioning variables on reagent adsorption and flotation performance. The two-year research project was awarded to Jacobs Engineering. Somasundaran, Inc., the University of Florida Mineral Resources Research Center, and the U.S. Bureau of Mines assisted Jacobs. Two mechanisms of anionic collector adsorption were detected by spectrographic analyses and confirmed by microcalorimetric measurements. The mechanisms provided a sound technical basis for the empirical practice of conditioning phosphate flotation feed at a high percent solids. Tests performed in laboratory and pilot-scale agitated tanks indicated that power intensity may be used as a reliable scale-up parameter for anionic conditioning of phosphate slurry. Excessive agitator speed during conditioning was found to be detrimental to anionic flotation performance. Some dimensional ratios of anionic conditioners were found to be consistent with good utilization of agitation energy. Laboratory conditioning and flotation tests demonstrated that adsorption of collector onto phosphate and the subsequent recovery of phosphate in anionic flotation were significantly influenced by the quantity and quality of water used in conditioning. Conversely, the quality of water used in flotation was more influential on the recovery of quartz in the concentrate. A comprehensive survey of anionic conditioners and conditioning practice in the Florida phosphate industry was also performed during this project. The study clearly showed that flotation testing with laboratory conditions typical of scientific research gives different results than laboratory testing with simulated plant conditions. The effects of test conditions on laboratory test results should be carefully considered by investigators planning and conducting applied research.

Jan 1, 1999

A general form of pore pressure in a saturated porous medium, which is subject to external forces it has the pressurization of a borehole in hydraulic fracturing, is derived. The pore pressure consists of two parts: the preexisting initial pore pressure and the pressure induced by fluid flow due to the pressure difference caused by pressurizing the borehole The initial pore pressure associates with the effective stresses in the stress, fields of crustal stresses and a thick hollow cylinder subjected to internal and external pressures. The pure pressure weaned by fluid flow is implied in Biot's (1941) constitutive equation for three-dimensional consolidation and proved to be the exact effective pore pressure (Nur and Byerlee, 1971). Using this general form of pore pressure, a general poroelastic model for hydraulic-fracturing breakdown (fracture-initiation) pressure was derived. This model was validated by laboratory experimental results on Indiana limestone. Three sets of tests were conducted under the conditions of preexisting pore pressures of 6, 21 and 28 MPa, respectively. The equal horizontal (confining) pressures applied in the tests ranged from 6 to 60 MPa. Hainison and Fairhurst's (1967) model appear to be applicable to rocks having microcracks or flows. Experimental results of fracture reopening pressures on Indiana limestone supported this assertion. The test results also demonstrated that, when the pressure difference between the confining and the initial pore pressure grows larger than 14 to 21 MPa, the breakdown pressures agree well with the general poroelastic model developed in this paper. This indicates that the developed model will be superior when hydrofacturing stress measurements are conducted at great depth.

Jan 1, 1997

By R. L. McNearny, K. A. Barker

Four numerical models written with the "PFC2D " program were compared against four similar physical models. The numerical models were constrained numerically to closely follow the caving behavior of the physical models. Results from the numerical analyses closely simulated both the granular and blocky behaviors of the physical models, including bridging and interlocking of the simulated orebody during draw. The drawdown patterns and the rate of draw developed during numerical modeling also closely simulated the physical models. The same assumptions and governing parameters used in analyzing the first four models were applied to an additional model. The fifth model employed a completely different, uneven, draw sequence than the other four models, allowing the material to flow in a more granular manner with a demonstrated instability of the undercut sections between each drawpoint opening. Drawdown patterns and behavior of the numerical material of the first four models progressed at uneven and inconsistent rates, similar to those seen in the physical models. By inspection, the overall shape and flow lines of both the numerical and physical models were close in the area removed and in the flow characteristics. The fifth model proved to be the most unstable of all the models tested, with poor correlation to the physical models. The uneven draw sequence, coupled with an additional frictionless wall condition and an added drawpoint, caused the material to flow in a very granular manner. Information generated by this study can be used as a first approach in determining the proper draw rate, drawpoint spacing and undercut thickness for a block-caving operation. Numerical models are often difficult to predict and interpret. However, this study should increase the confidence level for use of the PFC2D program in the future.

Jan 1, 2000

By H. Tutu

The legacy of gold mining operations continues to affect water quality in the Witwatersrand Basin in South Africa. The acid mine drainage (AMD) emanating from the tailings dumps liberates heavy metals from the ore minerals. The objective of this study was to characterise the geochemical processes that are important in understanding chemical evolution of polluted water in the study area. Analytical results for water samples collected in the catchment of the study area generally showed elevated concentrations of heavy metals in the vicinity of tailings dumps and mining operations and a decrease in the distal. Dams and wetlands, despite their proximity to the tailings dumps, recorded low concentrations of heavy metals and other pollutants. The characterisation of AMD was summarised in a conceptual model in which plots of redox potential versus pH and electrical conductivity versus pH were identified as the most important sub-models that captured the gross physical-chemical characteristics of polluted water and its interaction with the environment.

Jan 1, 2006

By S. A. F. Murrell, M. Hong, L. J. Bond

This paper investigates the propagation, interaction and scattering of explosively generated seismic waves with discontinuities in rock masses using numerical models which employ a finite difference method. The models consider 2-D systems and give a full solution including mode-conversion in the mid-frequency scattering region where feature dimensions are of the order of the wavelengths involved. The paper has two parts, the first of which considers wave propagation and diffraction by simulating an explosive body source in a half- space containing a step or a slot on the surface which represent a cliff and a rift valley that has dimensions of the order of the wavelengths in the source. The second part of the paper reports a hybrid technique which combines a perturbation method and the finite difference method for wave propagation again caused by an explosive body source in a 2-D half-space system but with a shallow surface obstacle, such as a smooth ridge, with elastic constants slightly different from bulk material and the slope of this surface topography are shallow. This hybrid technique is also reported being applied to a half-space with a horizontal void or insert.

Jan 1, 1986

By A. Ang-Ug, L. Gurieff

"The Phu Kham Cu-Au mine in Laos is owned and operated by Phu Bia Mining Limited. The deposit is a complex and low grade Cu-Au porphyry ore. The rougher feed has a particle size distribution of 80% passing 110 µm, and the rougher concentrate is reground for cleaning to 80% passing 25 µm. The Cu losses in the cleaning circuit are primarily in the <12 µm fraction. A randomised paired ON-OFF test of magnetic conditioning in one of the two parallel cleaner 1 circuits was undertaken. The results showed that with magnetic conditioning there was approximately a 10% reduction in the <12 µm Cu distribution in the cleaner 1 tail to a 98% level of confidence. The Cu distribution in the <12µm fraction is a less variable measure of changes in the <12µm Cu recovery, therefore, this was used to evaluate the impact of magnetic conditioning. Subsequently, magnetic conditioning was installed in both cleaner 1 circuits and the plant results monitored after this installation. Comparing the plant results immediately before and after this installation showed that there was a 20% reduction in <12µm Cu losses to the cleaner tail. INTRODUCTION The Cu-Au, Phu Kham Mine (PKM) is located within PanAust's Phu Bia Mining Contract Area in Laos, approximately 140 kilometres from the capital city, Vientiane. PKM is PanAust's flagship operation and the significant cash flow generated by PKM has supported PanAust’s growth, while contributing to a strong balance sheet. PKM comprises an open-pit mine and a conventional milling and flotation operation that produces and exports a Cu and precious metals concentrate. The concentrate contains around 23% Cu, 6 ppm Au and up to 35 ppm silver. Process Overview The PKM deposit consists of complex heterogeneous mineralogy horizons of Cu-Au stockwork and skarn mineralisation. It contains areas of soft-leached zones, overlying transition zones and supergene chalcocite dominant secondary Cu mineralisation and clay-rich gangue. Areas of high As and Zn also pose a challenge in treating the highly variable ore. In addition, hardness of the ore increases with deposit depth. The ROM is hauled to a primary gyratory crusher to produce a coarse ore stockpile with size distribution suitable for the 13 MW semi-autogenous mill. The SAG product feeds two parallel ball mills each equipped with a cyclone cluster producing a product particle size distribution of 80% passing 110 µm. The conventional flotation circuit consists of two parallel rougher banks. The rougher concentrates feed the regrind cyclone where the underflow is split and reports to two parallel, 3MW, M10000 IsaMills. The regrind mill discharge combines with the regrind cyclone overflow with a product particle size distribution 80% passing 25 µm and reports to the Jameson cell."

Jan 1, 2018

By Hans Ehdwall, Erling Strandon, Friedrich Steinhäusler, Victor A. Leach

INTRODUCTION The basis for any measures in radiation protection is the quantitative assessment of the radiation exposure. Due to the extensive requirement in health physics manpower and related cost it is necessary to develop certain criteria regarding the necessity of monitoring and the selection of population groups to be monitored. Depending on the overall objective of the particular programme, the specific requirements for the measurement of atmospheric levels of radon, thoron and their daughters for practical radiation protection purposes differ significantly for those in the case of research applications, such as use of data for epidemiological studies. As part of the OECD-NEA Programme on Radon Dosimetry and Monitoring Task Group 1 reviewed available models for lung dosimetry in the case of inhalation of radon 222, radon 220 and their daughters (James et al., 1981). Using defined reference atmospheres for underground- and open-pit mining conditions as well as for dwellings, normalized conversion factors were calculated for the mean bronchial dose (mGy) per Working Level Month exposure (WLM). Task Group 2 discussed the features and adequacy of the Working Level (WL)-concept as a physical correlative of the absorbed lung dose and its limits of confidence and accuracy (Johnson and Leach, 1981). The WL-concept was found acceptable for radiation protection purposes provided that modifying factors like particle size, unattached fraction and respiratory minute volume did not cause the effective dose equivalent per WLM as calculated by either the James-Birchall or Jacobi-Eisfeld lung models to be more than 50 % above that given by ICRP of 0.01 Sv/WLM. For application in epidemiological studies the WLconcept is considered acceptable if the calculated absorbed dose to the tissue does not vary by more than 50 % (at the 95 % confidence level) from that given for defined reference conditions. In the following, objectives and requirements for the measurement of radon, thoron and their daughters are discussed for operational health physics routine and special research applications according to the scheme outlined in Fig. 1.

Jan 1, 1981

By Gennaro G. Ph. D Marino

In order to improve handling of subsidence damages the Illinois Mine Subsidence Insurance Fund supported the development of novel cost-effective methods of repair. The research in developing the repairs was directed towards the most common and costly damages that had been observed. As a result repair techniques were designed for structurally cracked foundations in the tension zone; structurally cracked foundations in the compression zone; and damaged or undamaged tilted foundations. When appropriate, the postulated methods would result in: 1. significant cost savings (over conventional procedures); 2. a structural capacity greater than when the foundation was untracked; and 3. an aesthetic appeal. All the postulated repair methodologies were laboratory and/or field tested. The paper will summarize the essentials of each technique developed and the test results.

Jan 1, 1986

By Steven J. Schatzel, Kayode M. Ajayi, Marcia M. Harris, Zoheir Khademian

Predicting rockmass permeability is critical in evaluating various engineering designs, including estimating gas inflow to a longwall mine in the case of a hypothetical breach in the gas well. This study conducted field permeability measurements to validate a geomechanical model capable of predicting rockmass permeability during longwall mining. A series of slug permeability tests were conducted in an active mine in Pennsylvania. A model of the mine was constructed in 3DEC numerical modeling software, and permeabilities were calculated. The modeling results agreed well with the pre- and post-mining permeability measurements, showing the applicability of this tool to evaluate gas well stability near mine workings.

Feb 1, 2024

By Giin-Fa Fuh, Sally A. Shoop

An instrumentation program was developed based on the results of an analytical study of the geomechanical effects of longer longwall face lengths. Boundary element simulations showed that longer face lengths can cause in- creased face convergence and an increase in the shear stresses in the immediate roof. Empirical design methods predict that longer faces will cause little effect on abutment stresses as long as the roof caving is well behaved. On this basis, a longwall face instrumentation program was designed with emphasis on the interaction between face support and ground response for optimizing face conditions. At a 600-foot (183 m) face, five midface shields and two headgate shields were monitored with vary- ing hydraulic pump pressure. The instrumentation included six convergence rods with linear potentiometers to measure canopy-to-toe convergence; fourteen pressure transducers to monitor leg pressures; and two portable data loggers. Similar instrumentation will be in- stalled on a 750-foot (229 m) face for comparison. The results from the 600-foot (183 m) face indicate that a ground reaction curve, as determined from the relationship between the sup- port set pressure and the roof convergence, can be used to optimize the support pressure to control convergence, the key element to ground stability in the face area.

Jan 1, 1986

By A. B. Seal, C. J. Bise

Excessive noise has long been a hazard in the coal-mining industry. Studies conducted during the mid-1970s and mid-1990s consistently show that hearing loss within the mining industry persists, in spite of regulatory requirements and sampling technology advances. When the U.S. Mine Safety and Health Administration&apos;s new health standards to protect miners from hearing loss took effect in September 2000, the potential developed to reevaluate sampling approaches with regard to noise-source hazards, such as task-based methods. This paper describes results from a Pennsylvania State University research project now being conducted at an underground coal mine. Each occupation was reviewed, and a list of tasks or processes performed by each was generated. Traditional personal noise dosimetry, static sound pressure levels and equipment sound mappings have been performed. Job tasks indicating the greatest levels of daily noise exposure and contributions to noise dose have been identified and will be discussed.

Jan 1, 2003

By F. Michael Wahl

With the exception of reports on commercial deposits of kaolin, fuller&apos;s earth, and other specialty type clays, there is little published information on the extent, properties, and potential uses of the clay resources of Florida. Recent studies by the Florida Bureau of Geology in cooperation with the University of Florida and the U.S. Bureau of Mines have proven the existence of two extensive Miocene clay deposits, one in peninsular Pinellas County and the other in southeastern Charlotte County. Drilling and subsequent testing of the clays from these deposits indicate their potential for economic development. Both deposits consist of montmorillonite type clays, have an average thickness of 25 to 35 feet, and are overlain by unconsolidated Pleistocene sediments. Preliminary firing tests indicate that the clays from Pinellas County are a potential raw material for lightweight aggregate production. The clay has good bloating characteristics across an acceptable temperature range with a resultant aggregate density of less than 1.00 specific gravity. The clays from Charlotte County have poorer natural bloating characteristics but might well be used after treatment or with additives. The economic potential and locations of both deposits emphasize the need for locating similar clay resources in the state that might have economic potential so that land use planning and subsequent urbanization will not prohibit their development.

Jan 1, 1972

By Edward D. Elkins

CalMat Co. is one of the largest producers of construction aggregates in the United States. The CalMat Reliance plant is located in Irwindale, California, and is situated on an alluvial fan formed by the San Gabriel River. The fan deposits are of Quaternary age and were derived from granitic and metamorphic bedrock exposed in the San Gabriel Mountains to the north. The sediments are poorly sorted and range in size from large boulders to clay size particles. The coarse material is hard and durable and consists of quartz diorite, granodiorite, granitic gneiss, schist and minor amounts of volcanic rock. The matrix is comprised of silty sand with varying amounts of clay. Thin silt and clay lenses occur sporadically throughout the deposit. The clay content of the matrix and the degree of weathering of the coarse material increases with depth. Based on seismic data, the alluvial fan varies from 200 to 400 feet thick and overlies crystalline bedrock. The Reliance plant was constructed in 1971 and 1972. It has a nominal capacity of 1200 to 1400 tons per hour, and typically produces more than three million tons of aggregate products per year. Alluvial fan sediments are mined from a gravel pit situated adjacent to the plant. The material is fed through a mobile, 48- by 60-inch, in-pit jaw crusher, then transported by conveyor to the main plant to be processed. The plant is modern and highly efficient. It has a typical wet and dry circuit and is capable of producing a wide range of aggregate products. To extend the life of the plant, a 9,000 foot conveyor system is being constructed to connect it to a granite quarry operated by Azusa Rock Inc. The quarry is located north of Irwindale, and is 50 percent owned by CalMat Co. The conveyor will be used to export crushed rock from the quarry to Reliance. The existing plant will be modified to process the crushed rock.

Jan 1, 1995

By D. F. Symonds

INTRODUCTION Dense medium processes have been used to separate coal and ores for over a hundred years. In fact Sir Henry Bessemer first patented a process in 1858. In recent years, their importance relative to other gravity dependent processes has increased. This is particularly true in the coal industry where over 60% of all preparation plants operating in 1984 in North America (1) contained either dense medium vessel or cyclone circuits. In addition, the stringent product quality demands of the consumer, together with increases in mining costs, dictate that the cleaning circuits be both predictable and efficient. Dense medium systems are the most predictable and efficient of all gravity- dependent processes. The majority of the text of this chapter will be concerned with dense medium applications as they relate to the coal industry. However, the techniques and calculation procedures can be applied, in general, to all non-coal minerals (such as diamonds, marginal iron and lead-zinc ores and gravel) which take advantage of a difference in specific gravity between the saleable product and the reject. The object in dense medium cleaning is to produce a liquid whose effective specific gravity is between that of the concentrate and the reject. In which case the lighter product will float to the surface and the heavier product will sink to the bottom. Unfortunately, this simple process becomes complicated by the following practical necessities: (a) collecting and removing the float and sink products from the medium without disturbing the free settling effects; (b) maintaining and controlling the specific gravity of the medium; (c) separating and reclaiming the medium once the products have left the separating vessel; and (d) separating finer sized particles which take longer to fall through the dense, and often viscous, medium. As a result of the last issue (item d) two main types of dense medium separators have evolved: dense medium vessels and dense medium cyclones. Dense medium vessels are essentially large baths through which the dense medium flows at a relatively slow velocity. The lighter products float to the surface and are carried out of the vessel by the medium flow. The heavier products sink to the bottom of the vessel and are physically transported out either by means of a conveyor (usually a chain conveyor) or a rotating, lifting arrangement (Figure 1). They generally

Jan 1, 1986

By Marini David, Pigorini Andrea, Fuoco Stefano, Zurlo Raffaele

"The excavation of a tunnel in highly weathered and strongly fractured rock masses due to tectonic actions is still a challenge. In order to maintain reasonable productivity, excavation through a wide zone of highly tectonized rock mass requires a detailed, integrated study of the construction solutions and a monitoring system to minimize the process time and to optimize the adopted consolidation measures in accordance with a predefined matrix of possible support systems. This paper summarizes some interesting data acquired during the excavation of the Brenner Railway Base Tunnel system between Italy and Austria. The Brenner Base Tunnel (BBT) runs through the fault line between the European and the African tectonic plate. This big fault zone is called “Periadriatic Line.” In particular, data acquired in the exploratory-service tunnel have been analyzed. Furthermore, the base concepts for defining the consolidation and support solutions adopted for the excavation of the exploratory tunnel are described. INTRODUCTION The Brenner Railway Base Tunnel (BBT) is a system of underground structures and tunnels that is designed to connect Italy and Austria using new railway standards. It is based on high speed (HS) concepts and applies the European Standards for Interoperability (TSI). The railway includes twin tunnels for a total length of about 55.0 Km without considering the connection tunnels to the existing underground railway in Innsbruck. Including the latter, the total length of the tunnel system reaches 64 Km, and is among the longest tunnels in the world. The Italian section passes through the so-called ""Periadriatic Line,"" which is an important tectonic structure generated by the collision between the European and the African tectonic plates. Despite the extensive investigations carried out (boreholes down to 700 meter depth), significant geological and mechanical uncertainties inside the Periadriatic formations remained unsolved. In order to elevate the level of confidence and observe the behavior of the rock mass at a representative scale, the BBT Authority decided to excavate in advance the service tunnel, which has taken the function of an exploratory tunnel. The data and observations collected during its excavation would provide important insights for the design of the main tunnels."

Jan 1, 2016

By L. A. Morley

Electricity is a major cause of lost-time accidents and fatalities in the mining industry. Major hazards and unsafe practices that contribute to electrical hazards are identified in this paper. Recommendations for reducing electrical accidents in surface mining are given and are directed toward the following three areas: preventing equipment contact with overhead lines, preventing maintenance related accidents, and defining system protection techniques.

Jan 1, 1986

By G. Gregory Bryan

G. GREGORY BRYAN 33.1-DEFINITIONS 1. Engineering-Engineering may be defined simply as the science and art of making materials and energy serve the purposes of mankind. There are many fields of engineering, each with specialized branches. The basic fields are: civil, mechanical, electrical and chemical. Others may be specialized phases of one of these or a combination of two or more of them. Mining engineering, for example, requires a working knowledge of construction, mechanics, electricity, metallurgy, geology, accounting and economics, in addition to mining techniques or methods. Mining geology and geological engineering involve rocks and their structure and the forces that act upon them, and chemistry, physics and mechanics also are important to practitioners in these fields. Metallurgical engineering requires chemistry and physics but also a working knowledge of mechanics and electricity. The fields of engineering with which this section are concerned are those primarily involved in the finding, mining, processing and utilization of the natural mineral resources of the earth. They include geology, mining engineering and metallurgy, each with several specialized subdivisions. 2. The Engineer-The engineer is an individual who has had specialized training to qualify him to practice the profession of engineering. The term engineer is used here in its broadest sense to include such professions as certain applied branches of geology, physics and chemistry, whose practitioners may not have acquired engineering degrees but who, nevertheless, by training and experience in some area of the minerals industry, qualify under the above definition. To become a successful engineer, a person should have certain pronounced aptitudes and preferences, even before embarking upon the requisite course of training. Among the chief qualifications that the engineer-to-he must possess are: (a) a natural inclination toward mathematics and the physical sciences, and (b) intellectual and moral honesty. Among the qualities the student engineer must develop are: (a) independence of thought, open-mindedness, sound judgment and the ability to observe, deduce, plan and apply solutions, (b) the ability to articulate and convince, and (c) the ability to organize and direct the activity of others. These qualities are normally developed through sound education, followed by pro¬gressive experience. 3. The Consulting Engineer-The consulting engineer is an engineer primarily in the business of furnishing specialized advice and engineering services on an intermit¬tent, part-time or occasional basis to clients who do not have continuous or full-time need for those services. He must be able to make and take full responsibility for decisions and recom¬mendations where original thought is required. He should not be confused with the engineer, surveyor or technician who also may furnish services on an intermittent basis, such as regular periodic surveys, the overseeing of drilling programs and other such routine work as may require little original thought and planning. 33.2-THE PROFESSION OF CONSULTING ENGINEERING 33.2.1- QUALITIES REQUIRED A successful consulting engineer must first have, as a minimum, the qualities and preparation of an engineer. In addition, he must have sufficient knowledge,

Jan 1, 1973

By G. Viggiani, J. Bel, H. Wong, N. Losacco, D. Branque

"Within the framework of the European project NeTTUN, the Laboratory of Civil Engineering and Building Sciences of ENTPE in Lyon (France) is in charge of a large experimental campaign to investigate the impact of tunneling on neighbouring piled structures. For this study, an original reduced-scale (around 1:10) physical model of EPBS is used. This ""1g"" laboratory model is able to reproduce the main features of the excavation method. For this new experimental program, the miniature EPBS advances inside a large tank filled with a model soil (dry sand), in which instrumented piles were pre-installed. In this paper, the authors describe briefly the original 3D device and present results concerning the impact of tunneling on a single pile located above the tunnel. Different tunneling face pressure are studied in connection with the practice. Machine parameters, pile solicitations and stress-strain behavior of the soil mass monitored under real time conditions are discussed. INTRODUCTION When tunnels are constructed in urban areas, they often come close to pre-existing structures, such as pile foundations. Perturbations of tunnel construction on these neighbouring structures must be considered during design and construction of the tunnel. Ground movements due to tunnelling may induce bending moments, lateral and vertical loads, settlements and lateral deflections in the piles, which may lead to structural damage or failure of the piles or the supported structure. The interaction between piles and a tunnel in construction is a complex three dimensional problem. To date, several experimental approaches have been carried out to analyse the effects of tunnelling on piled foundations (Bezuijen et al., 1994, Loganathan et al., 2000, Jacobsz et al. 2004, Lee and Basset, 2006, Marshall and Mair, 2011, ). These different studies carried out in the laboratory on 1 g or centrifuged models aim at a better understanding of tunnel - piles interaction and a quantification of the influence of each dominating parameter on the structural responses. Parameters like foundation type (single pile, group of piles) and geometry, relative tunnel – pile position, volume loss induced by tunnelling, ground characteristics, pile loading history were considered. However, most of these experiments were carried out under plane strain conditions by modelling the volume loss due to tunnel excavation by decreasing the tunnel diameter or the radial support pressure. As a result, these models do not adequately account for the variations of settlements both in the longitudinal and the transverse direction, which can induce significant flexional and torsional effects on the structures. These effects are particularly critical and detrimental in the case of historical monuments."

Jan 1, 2016

By A. M. Wala

It is common practice in Appalachia, when extending the life of an existing mine, to acquire the adjacent reserves and extend the existing mine into it. Also, often the existing mine is renovated to accommodate the new conditions. The existing mining system and the track and belt haulage systems may be modified while the new property is integrated into the old one. All of these changes create new constraints for the mine ventilation system (M.V.S.) that require proper planning and control procedures. The authors describe and present the study that was carried out for the ventilation system of a newly expanded underground coal mine located in the Appalachian coal region. Discussed first is the process of correcting the ventilation system of the existing mine. Then, some of the stages of controlling the expanded system are discussed. Finally, numerical data for these steps are presented.

Jan 1, 1992