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By Dan Yang

Pile foundation designs are performed routinely based on geotechnical information available at the time of design, often with due consideration of large uncertainties inherent to soils and site conditions. These uncertainties frequently are the causes of piles being installed not the same as those designed, especially by factors beyond quality assurance and quality control. With a variety of both satisfactory and unsatisfactory pile test results from these nonconforming piles, the design engineers are required to examine the foundation performance as a whole against the project design requirements before signing off on them or calling for potentially costly remediation. Over the years, as-built analysis has been a consistent way of dealing with pile non-conformity and damage in our practice, avoiding many construction delays and it is an integral part of our pile foundation design. In this paper, the key elements of an as-built analysis along with several major bridge projects are presented.

Jan 1, 2010

By Raj K. Rajamani, Samira Rashidi

High pressure grinding rolls have been utilized in various operations during the past four decades, simply due to their inherent mode of breakage that offers metallurgical benefits with pronounced energy reduction. For every new application, wear and in particular roll surface wear protection has always been the focal point of HPGR trade-off studies. Wear remains an important issue throughout a mine’s life given inevitable variations in the ore deposits properties. Hence, the capability of continuous scanning of rolls provides ample information about any deviations in the design values as well as their effect on the wear pattern. In part I of this manuscript, we present the feasibility of in-line scanning of roll surface in a 200 × 100 mm lab-scale HPGR. First, the in-line scanning was developed in a mock-up roll and then the scanner was moved to the laboratory-scale HPGR. We present the choice of scanners and the methods adopted to achieve high-level accuracy of determining wear. Even though we planned for micron-level precision of scanning, the inherent variability in shaft rotation was higher than the variability in the roll diameter due to wear. The hundred-kilogram mass processed in the HPGR was not sufficient to create enough wear that is discernible to the in-line scanner. Yet, the method tested is a promising avenue for inline scanning of HPGR rolls.

By Chester Wells Purington

Situation.—The Camp Bird mine is in Imogene basin† (Fig. 1) at the head-waters of Canon creek, a branch of the Gunnison, in the southern part of Ouray county, Colorado, towards the northern edge of the region known as the San Juan mountains, and about 10 miles W. of the continental divide. It is 8 miles by wagon-road from Ouray, the terminus of a branch of the Rio Grande' Southern railway. The distance from Denver to Ouray is 387 miles by rail. In an air-line, the mine is 190 miles SW. of Denver. The altitude of the town, tunnel and buildings is 11,200 ft., and level No. 2 is 11,500 ft., and No. 1 is 11,670 ft., above sea-level. The lowest point of the lode-ontcrop, which crosses the basin E. and W., has an elevation of 11,850 ft., and that of the highest point, on the divide between Imogene and Tomboy basins, is 13,250 ft. On the eastern slope of the Imogene basin (towards Ironton) the vein is less clearly defined on the surface. Ownership and Extent.—At the time of the writing of this paper, the property is owned by Mr. Thomas I?. Walsh, and operated under the management of Mr. J. W. Benson. It

Jan 1, 1903

By A Scott, I Onederra

Most iron ores occur in mine benches as complex mixtures of lithologies and ore types. This significantly complicates their characterisation for both blast design and fragmentation modelling. A great deal of technical and research effort has been applied to the development of models to predict fragmentation from rock blasting. A number of quite useful engineering models are currently available to blasting engineers and consultants, and more sophisticated approaches using mechanistic descriptions of rock breakage continue to be developed and applied by researchers and explosives companies.The engineering or empirical models that are in more general use within the industry, such as the Kuz-Ram model, require appropriate data if they are to generate useful fragmentation predictions. Some of these models have reached significant sophistication and have made very useful contributions to both routine blasting operations and the exploration of new blasting paradigms. However, these models struggle to adequately deal with rock that is as complex as iron ore. This paper reviews the characteristics of the most successful blast fragmentation models available to the industry and discusses approaches to the derivation of suitable rock mass properties to adequately describe blast fragmentation in a range of iron ores.CITATION:Scott, A and Onederra, I, 2015. Characterising the blasting properties of iron ore, in Proceedings Iron Ore 2015, pp 481–490 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 13, 2015

By R. Frank Chiappetta, E. B. Wilson

"The maintenance records for AL-60 airlegs at Falconbridge Ltd. are used to demonstrate some of the procedures for the analysis of such data.The data are not representative of pure failure s of one type or another. In fact, the records are for the undefined pseudo-failures which are usually found in industrial operations. However, because the machines are brought to the shop only when inoperative, the individual recorded components are treated as failures. Manual calculations are conducted to show the analysis of variance (ANO VA) approach to determine whether certain data can be combined; only a limited number of the 206 machines being considered. The manual procedures continue with the weighting of the suspensions; i.e. terminations f or reasons other than the failure of the given component. After the data are sequenced in the proper order, the nature or pattern of the data is determined using the Kolmogorov-Smirnov (KS) test.It is recognized that these manual examples must be replaced by compute r methods 10 process voluminous data of this nature. Such programs are developed and available. However, a program called RELCODE is used in this case to correspond to the manual examples and to take into account the suspensions. These analytical procedures form the basis for those studies required for good maintenance management."

Jan 1, 1985

By B. D. Thompson

Many mines adopt necessarily conservative backfilling strategies due to a lack of understanding of their backfill behaviour. In the past five years, extensive instrumentation campaigns have focused on measuring in-situ cemented paste backfill behaviour. These tests have resulted in optimised backfilling efficiency through elimination or reduction of cure periods where; i) controls on backfill behaviour are understood, and ii) barricade pressures are demonstrated to be within a safe range using routine monitoring as a required QA/QC procedure. Recently, this work has been extended to consider hydraulic backfill operations. Two stopes have been instrumented at Vale?s Coleman and Garson Ramp mines. The instrumentation and deployment methods are discussed, and representative total earth pressure, pore pressure, and temperature data are presented. In one case, pressures in the stope are relatively low as drainage causes strength gain in the fill and so pressures are arched. In a second example, again, drainage causes strength gain in the fill, but increasing temperatures correlate with pressure increases even during downtimes in filling. These pressure increases are thought to be caused by thermal expansion of the backfill in confined locations. Generally, the instrumentation approach has proven successful in measuring hydraulic backfill behaviour and offers good potential for incorporation into a procedure to safely maximise backfilling efficiency through routine barricade pressure monitoring, when combined with safeguards to ensure adequate fill drainage.

Aug 1, 2013

By Ken Barish

Jane Mine of the Keystone Coal Mining Corporation was started in 1962 and is in the Lower Freeport seas located in Armstrong County, Pennsylvania, approximately 45 miles northeast of Pittsburgh. The mine is a slope/shaft complex with the cover ranging from 100 feet at the slope to 450 feet near the back end of the property. The seam height ranges from 48 to 72 inches. A variety of roof conditions have been en¬countered, and an equal variety of roof control systems have been tried with varying degrees of success. Initially, places could be mined as deep as 100 feet without any permanent roof support. After several problems and the advent of the Health and Safety Act of 1969, roof control became more and more prevalent and predominant at the Jane Mine. It started with 4 foot conventional oolts. As the mine progressed in the northeasterly direction, roof conditions changed from the extremely good roof that was encountered initially, to bad roof; and other types of roof support were required. Sixty pound rails and 6 inch 25 pound to the foot steel I-beams were used for supplemental support in long life headings such as belt and track. Resin bolting was done in many areas for long life support due to the deterioration of the shale roof over time. Several areas had to be abandoned because of uncontrollable top.

Jan 1, 1984

By J. L. Kohler

Component failures in the electrical control circuits of mining machines account for a large percentage of the total downtime of the machine, Once a failure has occurred it is always a tedious and usually a time-consuming task to locate the failed component. Moreover, the pressure to quickly locate the cause of a delay can lead to compromises in safety. Thus an onboard diagnostic system, essential for an automated machine, would be a very useful addition to existing machines. This report details U.S. Bureau of Mines development of a generic procedure for synthesizing diagnostic systems for electrical-control-circuit failures in mining machinery. A continuous mining machine is used as the testbed to illustrate the application of the developed methodology. Substantive differences among mining machine control circuits made it impossible to achieve a generic diagnostic system, but a generic approach for the synthesis of the diagnostic system was possible. As the research progressed, it became apparent that an algorithmic approach was better than an expert-system-based implementation. A prototype system was constructed and used to evaluate the diagnostic system. Prototype implementation issues are also examined.

Jan 1, 2010

By Raymond A. Bradbury

Martin County Coal Corporation operates three underground mines and two surface mines on Wolf Creek in Martin County near Inez, Ky. The original underground development was begun in March of 1970. The property being developed is leased from Pocahontas Land Corporation. The A. T. Massey Coal Company, whose offices are located in Richmond, Virginia, is the parent company and sales agent for Martin County Coal. Duke Power Company is the customer who will take all the production from the mines which ultimately are scheduled to produce 2,500,000 tons annually. The Norfolk and Western Railway Company built a 24-mile railroad into this huge reserve of low-sulfur steam coal. Four coal seams, all above drainage, are included in the lease. The Middle Coalburg and Stockton seams are being deep-mined now and it is in three mines that the diesel haulage equipment is used. Those of you who attended the AIME meeting in Birmingham last October or the Diesel Symposium in Pittsburgh in January of this year are familiar with the introduction of trackless diesel-powered haulage equipment into our Martin County mines. I made a presentation at each of those meetings which dealt with our first experience with Wagner Mining Equipment haulage units. These machines are sold exclusively by Lake Shore, Inc. whose offices are in Iron Mountain, Michigan.

Jan 1, 1973

By A. Felipe Uribe-Henao, Camilo Ballesteros, Luis G. Arboleda-Monsalve, David G. Zapata-Medina

Conventional excavation analysis based on total or effective stress methods can result in inaccurate estimation of ground movements when impervious soil conditions or rapid excavation sequences are not found in the excavation (i.e., assumption of undrained response is not valid). The influence of excavation rate, hydraulic conductivity, and excavation geometry on the fully coupled solid-fluid behavior of a braced excavation in cohesive soils are studied parametrically using PLAXIS2D. The coupled excavation analysis is performed using the Hypoplasticity clay model to reproduce the constitutive behavior of soil and the poro-elasticity Biot’s theory to account for changes in pore water pressure due to deformations in the soil skeleton. Results obtained from the parametric studies indicate that excavation rates to hydraulic conductivity ratios, ER/k, smaller than 0.1 and larger than 104 can be used as limits for drained and undrained analyses, respectively. In practical applications, undrained and partially drained excavation analysis with ER/k larger than 102 resulted in a similar ground deformation. However, smaller ER/k ratios demand fully coupled solid-fluid analysis. An analytical method aimed at predicting excess pore water pressures and determining the required type of analysis associated with soil and excavation conditions, e.g., drained, partially drained, and undrained analysis, is proposed herein to accurately estimate the ground movements induced by the excavation.

By Schneider, W. G.

IT is not my purpose to burden you with many statistics. The charts herewith should be considered merely as indicating the trend. I believe' that is what is really of interest to us. It is difficult, if not impossible to forecast with any assurance future developments, because of possible new mines, competitive materials, curtailment' or increase in the use of the metal in certain markets, and many other factors that have a vital bearing on any industry. Fig. 1 shows United States smeltet output of copper, starting with 1845. It is estimated that in 1928 the smelter output of copper will be about 1,010,000 tons. Between 1895 and 1905 it increased about 200,000 tons, and between 1905 and 1915 about 240,000 tons. Between 1915 and 1925 the increase was about 140,000 tons. This is an average increase over 30 years of about 190,00Q tons per ten-year period. At the present time the indications are that this demand for increased production will continue. As to whether or not we have the supplies or facilities to maintain this increase or a greater one, remains to be seen. Provided it is possible for United States smelters to increase their production, they should be producing at the rate of about 1,210,000 tons or more per year by 1935.

Jan 1, 1928

By David S. Graham, Benjamin Turner, Paul J. Axtell

Seismic challenges were at the forefront of design for two parallel replacement bridge structures over the Arkansas River as part of the I-30 Crossing Project in Little Rock, Arkansas. Although not an area of the country typically associated with high seismicity, proximity to the New Madrid Fault Zone resulted in design ground motions sufficient to trigger liquefaction in alluvial channel and point bar deposits. A detailed post-award subsurface investigation program utilized CPT with complimentary borings to obtain samples for laboratory testing to assess the continuity of potentially liquefiable layers, from which we concluded that continuous zones of liquefaction across the extent of the north approach could lead to lateral spreading towards the river. An overview of the foundation and superstructure design to resist lateral spreading forces in accordance with the latest published design guidelines and research is presented. Other seismic aspects of the design are covered including timber pile ground improvement to mitigate liquefaction at the north approach embankment and foundation input motions that differ from code-based ground surface motions due to foundation stiffness, strength, and geometry. The project showcases an example of successful collaboration between geotechnical and structural designers with contractor input to address seismic challenges in the South Central US. Furthermore, the importance of considering kinematic demands on columns and other superstructure components – not just foundations – is highlighted.

Sep 8, 2021

By Hjalmer Sjögren

AMONG the feldspar-rocks there are certain types which occur constantly in different areas-viz., the aruphibolitic plagioclase- rocks and the granulitic rocks Composed of quartz and alkaline feldspars. Among the latter soda: granulites as well as potash are met with; also the corresponding gneisses occur. GROUP I.-THE ORES OF THE ARCHEAN CRYSTALLINE SCHISTS. The Rocks. The ore-bearing rocks of the ore-province of central Sweden are chemically and petrographically unlike the more monotonous gneiss- and granite-areas which surround them. On the whole, they constitute a quartz-feldspar formation in which purer quartzitic rocks, limestones, " skarn " rocks, and ore-bodies are very subordinate members. (Skarn is the Swedish name for rocks of varying composition, mostly consisting of lime, magnesia, iron, and alumina, silicates of the pyroxene, amphibole, and garnet groups; as secondary minerals, epidote, chlorite, biotite, and talc occur. The skarn is scarcely an independent rock but is connected with the ore-deposits. It is formed through an interchange between the silica of the quartz-feldspar rocks and the basic constituents of the ore-formation.) [A BRIDGED SUMMARY.-The amphibolites must be considered as stretched and dynamo-metamorphosed dioritic rocks. The granulites are divided into two groups, one showing predominant plagioclase, the other equal or predominant orthoclase. Evidently, the iron-ore deposits are connected in some way with the

Jan 1, 1913

By P. Michael

Proponents of geomorphic mine land reclamation have criticized current reclamation practices in the coal fields of steep-sloped Central Appalachia as too narrowly focused on civil engineering principles and neglectful of the functional and aesthetic benefits of reclaiming mine sites in ways that mimic natural landforms and drainage patterns. They observe that current mining and reclamation practices are radically transforming the mountain-and-valley terrain into gigantic flat plateaus and, in doing so, disrupting the beauty and ecology of the natural landscape. Instead of designing and constructing linear or planar surfaces and unvarying slope gradients during the reclamation process, they recommend ?landforming,? i.e. the adoption of curvilinear, compound slope forms that blend well with the surrounding physiography and represent the result of naturally stabilizing geomomorphic processes. The authors feel that the concept of geomorphic mine land reclamation is sound, however, its application to the Central Appalachian coal fields faces significant--albeit not insurmountable--challenges. They include: (1) existing reclamation enforcement regulations that are focused on civil engineering principles and not explicitly supportive of geomorphic methodologies; (2) regulatory agencies? current intent to limit the down-gradient reach of excess spoil fills in order to allay disruption or burial of natural streams; (3) actual or perceived increases in reclamation costs; and (4) the challenge of designing and constructing ?natural? landforms that are mature and stable in an otherwise youthful, erosional landscape.

Jan 1, 2010

By Raj K. Rajamani, Samira Rashidi

High pressure grinding rolls have been utilized in various operations during the past four decades, simply due to their inherent mode of breakage that offers metallurgical benefits with pronounced energy reduction. For every new application, wear and in particular roll surface wear protection has always been the focal point of HPGR trade-off studies. Wear remains an important issue throughout a mine’s life given inevitable variations in the ore deposits properties. Hence, the capability of continuous scanning of rolls provides ample information about any deviations in the design values as well as their effect on the wear pattern. In part I of this manuscript, we present the feasibility of in-line scanning of roll surface in a 200 × 100 mm lab-scale HPGR. First, the in-line scanning was developed in a mock-up roll and then the scanner was moved to the laboratory-scale HPGR. We present the choice of scanners and the methods adopted to achieve high-level accuracy of determining wear. Even though we planned for micron-level precision of scanning, the inherent variability in shaft rotation was higher than the variability in the roll diameter due to wear. The hundred-kilogram mass processed in the HPGR was not sufficient to create enough wear that is discernible to the in-line scanner. Yet, the method tested is a promising avenue for inline scanning of HPGR rolls.

By Thomas R. Kuesel

Just south of the L'Enfant Station in Seventh Street, the WMATA system splits into two branches, each comprising twin single-track soft ground tunnels. Immediately at the beginning of the section, Interstate Route 95 crosses transversely over the alignment in open cut, removing most of the cover over the tunnels. Seventh Street spans I-95 on a bridge whose abutments and pier also cross transversely over the four tunnels, with their footings as little as 7 feet above the tunnel crown (Figure 1). Soil investigations revealed that the tunnels would have to be driven through mixed face, with a clay invert and a waterlogged sand crown. Thus, there was a good chance that the roof would fall in, leaving 1-95 and the Seventh Street Bridge in a crater. Since there was no roof that could be counted on, these were figuratively (and potentially truly) Washington Metro's Topless Tunnels (Figures 2 and 3). DESIGN ALTERNATIVES Faced with this situation, the designers considered several options, including temporary detours that would permit demolition of the bridge and building tunnels under the 1-95 Freeway by cut-and-cover methods. They also investigated structural underpinning of the bridge and freeway pavement, and strengthening the bridge abutments and center pier by post-tensioning to enable them to span over any subsidence trough.

Jan 1, 1976

By Paul C. Merritt

Chrysotile asbestos producers in Quebec may soon experience a unique situation-i.e., strong competition from American ore sources for the short fiber market west of the Mississippi River. This com- petition will be forthcoming from Copperopolis and Coalinga, two deposits now being developed on opposite flanks of the San Joaquin Valley in central California. The combined output now planned from both deposits is 100,000 tons annually, equivalent to about 50% of the annual market demand in the western, central and Gulf States, and more than twice the tonnage sold in 1960 by all other American asbestos producers combined. The principal companies involved in these new undertakings are Jefferson Lake Asbestos Corp. (subsidiary of Jefferson Lake Sulphur Co.), Hidden Splendor Mining Co., Coalinga Asbestos Co. (Johns- Manville Corp. in conjunction with Kern County Land Co.), Union Carbide Corp., and Asbestos Corp. Ltd. Jefferson Lake's principal interest is at Copperopolis where the company's new 70,000-ton per yr mill recently went on stream. The company also holds some claims at Coalinga, but this latter area is better known as the site where Hidden Splendor, Coalinga Asbestos Co. and Todd Industries (a local company) have established operating mines and mills capable of turning out 30,000 tons of fiber each year. Coalinga is also the site of exploration by Union Carbide Nuclear and Asbestos Corp. Ltd.

Jan 9, 1962

By Alan Bye, Nick Beaton, Wayne Stange, Emmy Manlapig, James Groutsch

"For over 50 years the JKMRC has applied a unique education-based research strategy to develop modelling and simulation tools that are "fit for purpose" for industrial application. These tools are widely used for the analysis and optimisation of mining and mineral processing systems. As the mining industry context evolves to deal with declining head grades, falling commodity prices, professional skill shortages, and an exponential growth in the volume of data, a re-evaluation of what "fit for purpose" means in the future is required. It is contended that future industry needs for simulation-based decision support requires tools and systems that incorporate: • Multi-component modelling, • Models of complex sensor behaviour, • Integration across the physical value-chain e.g. resource to market, • Financial analysis including risk and uncertainty assessment, • Enabling multi-criterion decision making (technical, financial and environmental), • Ore-body knowledge at multiple scales, • The use of fundamental numerical models to provide insight for the development of practically useful models, and • Decision support delivered through remote operations centres. JKMRC and CRC-ORE are collaborating to develop a next-generation simulation-based decision support system that assists in addressing these challenges. The Integrated Extraction Simulator (IES) combines many years of pragmatic and successful work integrated with modern technology trends - in particular the rapid move to cloud-based computing."

Jan 1, 2014

By Nima Nabavi

Shovels and excavators have significant blind spots due to their large sizes, increasing the chances of collision with other surrounding equipment such as haul trucks, loaders, and dozers. While a camera surveillance system is very useful in preventing collision, it can benefit from two additional features: (i) the ability to display the distance of the closest object within the view, and more importantly (ii) the ability to warn the operator if objects are getting too close. After a comparison between few different technologies, it is explained how these features can be provided by integrating rugged pulsar radar sensors with a camera system. The specific radar technology is already field proven in the harsh mining environments. Motion Metrics International Corp. has developed this exact product, which combines its 4-camera surveillance system (ViewMetricsTM) with a series of rugged radar sensor elements, named ViewMetricsTM-Radar. The radar system employs intelligent CAN bus communication to reduce wiring, hence improving hardware reliability with built-in troubleshooting features. A USB connection is the only hardware bridge between the radar sensors and the embedded computer. As such, an existing ViewMetricsTM system can be easily upgraded to ViewMetricsTM-Radar. As addition of new interfaces to the cab could result in operator distraction, this paper explains how ViewMetricsTM-Radar reduces distraction compared to other radar collision prevention systems.

Oct 1, 2009

By Z. Song

Real-time monitoring makes it possible to detect any disturbance occurring in production, while decision instruments can efficiently assist decision-makers to optimize production, reduce iterative workload, obtain better solutions, and preview possible results. Technologies for the above already exist and have been proven in the process industry, i.e. refining and smelting. Optimization is also essential for profitable and stable mining production. Real-time monitoring has already taken hold in mining operations, especially in surface mining, while optimization techniques have also been widely used in underground mining, particularly for planning and scheduling. This review is limited to the hard-rock mining production of metallic ores such as gold and copper. It reviews optimization techniques developed for mine planning and scheduling, and communication technologies suitable for underground applications. It also presents control features for individual operation units, and discusses the technical viability of a mining production real-time optimization (MPRTO) system for underground mines, with possible benefits and challenges. Operational disturbances always occur in mine production. An MPRTO system can be useful to maintain operational effectiveness and efficiency by allowing quick changes to short-term plans. This paper briefly describes the MPRTO system, including the input, output, and basic algorithms. The technical prerequisites for the system specified here are already available. Further studies that are required to improve the system are discussed. Keywords real-time optimization, underground mining, production, operation.

Dec 1, 2013