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By Tran K. Van, Francois E. Heuzé, Richard E. Goodman

Sound design of structures founded in or upon rock requires that the deformability of each rock member involved be characterized. This can be done by means of loading tests (plate bearing, flat jacks, borehole jacks, pressure chambers, etc.) or through convergence measurements (tunnel convergence, roof sag, etc.) in exploratory works. Analysis of data will be qualitative (degree of nonlinearity, creep behavior, scattering of results over a number of sites, etc.) and quantitative (modulus of elasticity or deformation). Some of these tests involve a very bulky apparatus and are expensive to perform. On the other hand, for the purpose of mapping and describing the various rock members which occur within a given site, many feet of diamond drill holes are frequently completed. Even with the optimum equipment and expert drillers, however, quantitative characterization of the rock units on the basis of tests on returned samples is apt to be misleading; the softer and weaker components of the rock tend to be lost and the fabric of the rock block- fracture system in situ is not sampled. Laboratory moduli of elasticity have proved to be consistently higher than in-situ values selected for engineering purposes. This led to the design of instruments which would operate in boreholes, combining the advantages of a reduced size and a deeper investigation, from the surface to several tens of feet. BOREHOLE DEFORMABILITY MEASURING INSTRUMENTS In the last 10 to 15 years, a number of testing devices have been con- structed which can be inserted into a borehole to apply a load and mea-

Jan 1, 1972

By Revendra Awasthi

The application of a horizontal inclinometer and a tiltmeter to measure tilt, curvature, and deformations of shallow footings during mine subsidence is described. The measurements were taken during mining of a longwall panel in Southern Illinois and were supplemented with precision level survey data. Monitoring was conducted under a cooperative agreement between the Institute for Geotechnology at The University of Tennessee, Knoxville, the U.S. Bureau of Mines, the National Science Foundation, the Illinois Mine Subsidence Insurance Fund, and Old Ben Coal Company. Six different footings were constructed and instrumented at two sites; one above the panel centerline, and the second inside the edge of the panel in the anticipated zone of maximum tension. A brief description of the inclinometer casing and tiltplate installation is described, and the results obtained from the two instruments on a plain concrete footing compared. Observations of footing deformations and curvatures calculated from the inclinometer and tiltmeter data are also presented, and the results compared with observed structural damage.

Jan 1, 1990

By E. V. Cilento, K. A. DiGregorio, R. C. Lantz

"K. A. DIGREGORIO, E. v. CILENTO, AND R. c. LANTZ. Measurement of superoxide release from single pulmonary alueolar macrophages. Am. J . Physiol. 252 (Cell Physiol. 21 ): C677-C683, 1987.-An electrooptical method was developed to quantify superoxide (02) release from single rat pulmonary alveolar macrophages (PAM) during adherence to the bottom of a culture dish. This was done by measuring the reduction of nitro blue tetrazolium (NBT) to a diformazan precipitate at 550 nm from videorecorded images of individual cells. Temporal changes in cell optical density, which are proportional to the mass of diformazan produced, were calculated from videophotometric measurements of the change in light intensity over individual cells. Total diformazan produced increased 78 and 1263 with an increase in NBT from 0.5 to 1.0 and 2.0 mg/ml, respectively. Total diformazan produced and maximum rate of production among individual PAM varied two- to threefold providing strong evidence for heterogeneity in 02 production. Specific inhibition of 02 production by superoxide dismutase, iodoacetate, and chlorpromazine significantly reduced the total diformazan produced and maximum rate of diformazan production. Hydrogen peroxide was not involved in NBT reduction, since catalase alone did not significantly change diformazan production. This novel method to quantify 02 release from single PAM should be valuable in analyzing heterogeneity and single cell kinetics of O; production, in assessing the effects of exposure of cells to particulates on O; release, and in relating release to electrophysiological measurements.rat; nitro blue tetrazolium; macrophage heterogeneity; single cell kinetic PULMONARY ALVEOLAR MACROPHAGES (PAM) protect the lungs by phagocytizing foreign debris and bacteria (24). This process involves ingestion as well as destruction of foreign matter. Phagocytosis is usually accompanied by a respiratory burst that increases cellular oxygen consumption and glucose metabolism in the hexose monophosphate shunt (7), which leads to the release of highly reactive oxygen metabolites at the surface of the · plasma membrane (6, 27). These agents have been implicated in the killing of bacteria by phagocytes (22), but have also been shown to be toxic and have been linked to cancer, emphysema, arthritis, diabetes, and other diseases (17, 22, 30). Toxic effects may be a result of either an abnormally low production of metabolites, resulting in damage to lung tissue by respirable bacteria and dusts, or an abnormally high production, resulting in direct damage to lung tissue by metabolites themselves."

Jan 1, 1989

By Maria Sullivan

There have been many papers and articles presented over the last 60 years questioning the relevance of the 8-millisecond blasting delay window as an ‘Industry rule of thumb’. The concept of using delays between blast holes to minimise vibration is well understood and agreed upon. The means for evaluating what that minimum delay interval needs to be, for a particular site given their ground conditions, design parameters and blasting techniques, is much less established. Some sites haven’t even recognised their required minimum delay value may not be 8-milliseconds!

Feb 6, 2023

One of the earliest and continuing challenges in driving sustainable development in large scale resource industry projects is around the issue of assessment û how do you measure the sustainability of a mineral operation? One of the key road blocks when confronted with this challenge is the temptation of technical folks to reach for a definition of sustainability or sustainable development. But definitions, by definition, have boundaries and limitations that serve to constrain thinking û they limit the thinking of what we can achieve with sustainability (it also acts as a barrier that constrains innovation). Rather than seeking definitions, better understanding of the core perspectives around sustainability and their application to the minerals industry provides a much more powerful platform from which to conduct assessments. But it is only when these perspectives are combined with the right framework and supporting techniques that the complex becomes doable. With the support of the perspectives and the framework, various assessment and measurement methodologies can be used; the challenge is communicating to stakeholders the sustainability character of the project in ways that are meaningful and to which people can connect. Assessment is not about finding the best or most accurate methods that fulfil strictly academic and possibly abstract requirements. The challenge is to help people understand what the impacts are, and what the value contributions will be, in a format and language that make sense in their world-view.

Jan 1, 2009

By T van Niel, M Trefry, B Baker, I Rea, A Hawdon, D McJannet, D Boadle, R Fandrich, A Littleboy

Many open cut mines extend to depths well below the natural water table level with constant dewatering required to maintain operations. When mining activities cease the groundwater starts to fill the void and pit lakes form. The resultant pit lake is directly connected to the surrounding water table and understanding the hydrological and chemical evolution of these lakes is important for minimising environmental impacts. In Western Australia alone there are currently 1800 mine voids and more than 150 mines operating below the water table (Johnson and Wright, 2003). In conjunction with BHP Billiton Iron Ore, CSIRO has been undertaking research to measure and model rates of evaporation from pit lakes in the Pilbara region of Western Australia. Extreme high temperatures and low humidity ensures that this region experiences the highest evaporation rates in Australia.CITATION:McJannet, D, Hawdon, A, Boadle, D, Baker, B, van Neil, T, Littleboy, A, Trefry, M, Rea, I and Fandrich, R, 2016. Measurements and modelling of evaporation from abandoned mine pit lakes, in Proceedings Life-of-Mine 2016 Conference, pp 106–109 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jun 28, 2016

By Clifford C. Hanninen, Allan H. Caverson

Within the past nine years a means for measuring the distance between mine roof and floor was developed at the White Pine mine which yields relevant information utilized in the mining operation. The technique known as "convergence" is an efficient, low cost way for obtaining large quantities of data for predicting roof falls, caving activity and overall mine stability. Since 1964 the activity of convergence measurements has expanded to become a production tool found in all sections of the mine. The program involves four types of activity: 1) monthly measurements in areas known to be active and in sample blocks scattered throughout the mine for a long-term stability study; 2) semi- monthly measurements along vital travel roads, belt drifts and compressor sites; 3) weekly measurements in areas where men are working; 4) daily measurements in pillar-recovery and caving operations.

Jan 5, 1973

By Atta B. Yiadom, A. David Miller, Robert C. Kirby, Sean M. Todaro

"San Pablo Dam is a 170-foot (52-meter)-high earthfill embankment, located approximately 10 miles (16 kilometers) north of downtown Oakland, California, that impounds a 38,600 acre-feet (47.6 million m3) reservoir for customers in the East Bay Municipal Utility District's (EBMUD's) service area. Seismic upgrades were designed and constructed in 2008 through 2010. Work included removal of an existing 140,000 cubic-yard (107,000 m3) downstream buttress, which was replaced with an enlarged 300,000 cubic-yard (230,000 m3) buttress founded on alluvium and colluvium that were improved in-place using Cement Deep Soil Mixing (CDSM) technology. The site characterization for the project, design of CDSM, reuse of CDSM spoils as construction materials, and environmental permitting have been described in five previously published professional papers.This paper provides a brief summary of the design of the seismic upgrades and presents the results of measurements made during and/or after construction including the variation of CDSM strengths with time, piezometric levels within the dam and foundation soils, and seepage flow rates. These measured values are compared to the values estimated during design of the seismic upgrades.INTRODUCTIONSan Pablo Reservoir is located approximately 10 miles (16 kilometers) north of downtown Oakland, California, as shown in Fig 1. As many as 50 million gallons (200,000 m3) per day pass through the reservoir for treatment and distribution to a portion of the 1.3 million customers served by EBMUD. The dam is founded mainly on alluvium and was originally built in 1920 using materials excavated from the left and right abutments consisting of siltstone, claystone, fine-grained sandstone, mudstone, and shale that were excavated and placed using hydraulic fill methods. The dam is located within two miles (three kilometers) of the Hayward Fault which is capable of a moment magnitude 7.25 earthquake.Because of the foundation materials, construction method, and proximity to the Hayward Fault, the dam has undergone a series of seismic improvements, including the placement of a downstream compacted earth buttress in 1967 and an upstream compacted earth buttress in 1979. In 2002, the State of California Division of Safety of Dams (DSOD) requested that EBMUD evaluate the seismic stability of San Pablo Dam, following the results of a study that same year that indicated a 62 percent chance of a greater than 6.7 magnitude earthquake striking the San Francisco Bay region between 2003 and 2032. The dam was evaluated and it was concluded that portions of the underlying foundation soils may liquefy during the maximum credible earthquake which could cause the dam to become unstable."

Jan 1, 2015

By Jesse Puller, Ken W. Mills, Owen Salisbury

"An underground coal mine located in New South Wales has a target coal seam located 160-180 m deep directly below a 16-20 m thick conglomerate unit that has been associated with significant periodic weighting events on the longwall face. As part of the investigations to better understand the causes of periodic weighting at the mine, inclinometers capable of measuring horizontal shear movements through the full section of the overburden strata were installed ahead of mining at two locations approximately 1 km apart above the centre of two longwall panels. These inclinometers were monitored as the longwall approached each site. This paper presents the details of the installation, the results of the inclinometer monitoring at both sites, and the insights that these measurements provide for overburden behaviour about longwall panels.Horizontal shear movements were observed to develop on shear horizons that correlate closely across the two sites suggesting a mechanism that is consistent across a large area of the mine. Shear movements were observed to develop on a single horizon near the top of the conglomerate strata that was mobilised almost immediately after initial formation of the longwall goaf at a distance of 425 m ahead of the longwall face. The direction of horizontal movement was consistent with the relief of the major principal horizontal stress. As the longwall face approached each inclinometer, other horizons within the upper part of the overburden strata begin to shear with the upper strata moving toward the approaching goaf more than the lower strata. Within the last 30 m of longwall approach, tilting of the strata associated with the increase in vertical subsidence toward the extracted goaf caused a change in the style of deformation with tilting and reverse shear offsets.INTRODUCTIONLongwall mining is recognised from subsidence monitoring, surface extensometer measurements, and various other observations to cause significant disturbance to the overburden strata directly above the extracted goaf of each longwall panel. Disturbance to the overburden strata beyond the limits of each longwall panel is not so well understood. Subsidence monitoring indicates that horizontal movements beyond the edges of the extracted longwall panel are generally greater in magnitude than vertical subsidence and horizontal movements may extend up to several kilometres from the edge of the panel in some circumstances (Reid 1998, Reid 2001, Hebblewhite et al 2000, Mills 2001, Mills 2014). The mechanics of how these movements are accommodated within the overburden strata is only poorly understood and there are few direct measurements."

Jan 1, 2015

By O. A. Bascur

Ores are becoming extremely variable with mineralogy and hardness disturbing the grinding and flotation circuits. The current grinding and flotation sensors provide large amounts of data for process optimisation. Adding the right context and operational events augments operational knowledge for proactive actions to improve the performance of the grinding and flotation circuits. A data-driven strategy is needed to enable operations, maintenance, and business personnel to quickly and easily take corrective action when abnormal conditions occur. A digital plant template transforms data into operational insights in real-time. It uncovers the hidden, idle and downtime losses. By measuring and managing these unproductive times, people find new ways of avoiding them, improving the profitability of the plant. The information created by the real time analytics enables the calculation of recovery in real time and develops predictive analytics models to find the best operating condition based on the type of ore currently mined. The creation of new workflows and collaboration between mining and concentrator plant and the enterprise, including services providers, are enabled. A grade recovery model is used to identify the best operating conditions in real-time. An optimal Gaudin size distribution shape is used to find the grinding operating conditions that optimise the metal recovery in the rougher sections of the mineral processing plant. Sensors in the flotation circuits enable estimation of metal recovery and determine the optimal froth depth and aeration profiles, using an industrial air holdup flotation model. The implementation of a recovery/grind strategy with industrial examples in non-ferrous metal concentrator is presented in the paper. Keywords: Digital transformation, soft sensors, predictive analytics, grinding flotation optimisation, flotation bubbles, particle size, particle size distribution shape, froth aeration profiles, flotation air hold up model, recovery predictive analytics

Jan 1, 2020

By H Kurth

"The focus of this paper is on measuring the composition to improve mill feed quality to minimise the processing of waste, optimise process performance, reduce processing costs and minimise the generation of tailings.Technologies used since the 1990s in the cement and coal industries for measuring conveyed materials have been operationally proven and effectively derisked. Despite this the acceptance by the minerals industry has been very slow except in iron ore. Real-time penetrative full stream measurement using prompt gamma neutron activation analysis (PGNAA) for multielemental analysis and microwave transmission for real-time moisture analysis provide representative, tonnage weighted dry weight per cent results on a minute by minute basis. Analysis is unaffected by particle size, dust, layering/segregation, mineralogy and belt speed. The technologies are explained and performance examples given. The benefits derived from real-time compositional analysis are predicated upon a good understanding of deposit geology, mineralogical associations, waste to ore interfaces, amenability to mining, metallurgical processes and downstream customer requirements. Processing may include basic preparation in the case of direct shipping ores, minor beneficiation using simple upgrading methods, or concentration using more complex processing systems such as flotation, leaching or many others. The value of real-time data from primary crushed conveyed flows, using analysis of increments smaller than a single haul truck’s load, is very beneficial in process plants aiming to reduce waste processing, increasing feed grades and increasing metal recoveries. Grade variability can be utilised to divert conveyed increments of waste, direct shipping ore (DSO) quality material bypassing beneficiation, and subeconomic material amenable to upgrading diverted for further preconcentration by particle separation (sorting, heavy medium etc). Paybacks of a few months have been commonly achieved where the real-time technologies have been applied in the minerals sector. The paper outlines proven applications and case studies and proposes some innovative applications.Citation:Kurth, H, 2016. Measuring and Utilising Ore Quality Variability Using Real-time On-belt Elemental Analysis to Improve Mill Feed Quality, in Proceedings 13th AusIMM Mill Operators’ Conference 2016, pp 239–244 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Oct 10, 2016

By S. Mason

Many organizations are realizing that continual improvement in health and safety relies on addressing the potential for various forms of human error. Of these, violations are often the most frequent form associated with accidents. These occur when an individual, or individuals, deliberately contravenes established and known safety rules. They have been associated with up to 90% of accidents and incidents in some industries and yet rarely receive the systematic attention they deserve in the promotion of safety. This paper presents underlying motives which cause violations. These can vary significantly from mine to mine and from job to job. Managers need some measure of attitudes to determine the underlying motives behind violations if they are to determine effective strategies for promoting safe behaviour. Questionnaires form the starting point to address attitudes and the motives behind rule violations. The choice of the most suitable questionnaire, however, will vary from organization to organization. Guidelines on the choice of questionnaire are offered.

Jan 1, 1998

By Hairong Zeng, Shahram Tafazoli, Edmond Chow

Blast fragmentation is one of the main parameters for optimizing mineral processing, but reliable data is difficult to acquire, resulting in unpredictable performance and efficiency. Crusher and grinder circuits are designed to process specific rock size ranges. Oversized rocks require extra energy to reduce before feeding into the process, and undersized rocks indicate that the process is not used to its full extent. Blast design is the key to controlling the blast fragmentation, so the ability to accurately monitor the particle sizes is imperative.

Jan 1, 2011

By Charles Zdazinsky

Many blasting applications in the mining industry demand that the hard rock being blasted remains structurally competent. For example, pre-splitting is a common technique to reduce fracturing, and operators of dimension stone quarries use this blasting method to eliminate overbreak. When pre-split design parameters are not applied correctly, there will be a redistribution of stresses within the rock, resulting in Blast Induced Rock Damage (BID). Advances in geophysical technology are enabling blast technicians to monitor BID and then use the results to correctly design their blasts.

Jan 1, 2011

By M. J. Farrell

The threat of global warming and its prominent position in public discussion and political debate requires all industry to take stock of its contribution to rising atmospheric concentration of greenhouse gases. For the primary metals industry, the first step must be to identify the pattern and range of emissions at each step in the production chain. Only then can the industry assess the economic consequences of the penalties on emissions that will be imposed by governments and regulators and devise cost-effective plans to avoid or mitigate such penalties. While some work has been done to estimate carbon dioxide (CO2) emissions using Life Cycle Inventory analysis, this approach is less useful than site-by-site emissions estimates. It is the level of specific emissions at each site that will ultimately deter-mine carbon taxation liabilities and participation in emissions trading schemes. Most mining companies have moved with the times to issue sustainability reports for their operations. But in the absence of any standardized reporting format, it is difficult to make useful comparisons between even the best-reported producers on a like-with-like basis. For this reason, Minecost.com modeled the use of fuels and energy used in mining, milling, shipping and metallurgical treatment to cover ?cradle-to-gate? emissions of greenhouse gases resulting from the production of the major base metals copper, zinc, lead and nickel. Greenhouse gas emissions ? overwhelmingly carbon dioxide ? are associated with the consumption of energy at every step in the production chain, from exploration through mining to the production of refined metal. Producers of primary metal employ diverse technologies to mine, mill, smelt and refine several different types of ore. Every orebody has its own special characteristics. In addition, most base metals are produced in concentrate that must be transported to smelters, with con-sequent emissions consequences.

Jan 1, 2009

By Wallace W. Roepke, James C. Church

Introduction The history of mining machine development has been and is one of "bigger is better." While this may not always be true, it is currently the only approach open to machine designers without specific in situ cutting force information. The US Bureau of Mines has tried to modify this approach by supporting research, both in the laboratory and in field tests, that demonstrates that bigger is only better if the equipment is used correctly. In-house research has shown conclusively that deeper cutting reduces both dust and energy (Roepke, Lindroth, and Myren, 1976). This approach has been applied to a large Lee-Norse (LN456) continuous mining machine, which confirmed that slow deep cutting is beneficial and does not have a negative effect on production (Black and Rounds, 1977; Black et al., 1978). Specific in situ engineering data needed on coal cutting forces have not, however, been obtained by field tests with the LN456. Although the machine was instrumented to obtain data on one seam, it would be impractical to move the machine from mine to mine. It became apparent that a portable, easy to use device was needed for obtaining coal cutting forces in situ. Such a device could provide the engineering data needed by manufacturers, the site-specific cutting information needed by operators, and a field research tool to establish correlation with laboratory cutting tests. Design and Development According to a set of design guidelines established by the Bureau, the proposed device should be able to measure cutting forces directly with standard coal cutting bits, be transportable by two miners, and be self-contained. These guidelines were given to Ingersoll-Rand Research Inc. (IRRI). The contractor performed a rigorous review of 16 existing in situ portable tester designs, none of which could use a standard coal cutting bit to measure cutting force directly. These included a wide range of devices, all of which are discussed in the final report (Banerjee and Wisner, 1982). A series of design tradeoffs were established to satisfy initial design guidelines. The final deci¬sion was heavily weighted by an industry survey to determine the preferred concept from four man¬ufacturers and four operators. To assure ease of use with maximum information, all respondents wanted a linear cutting device that could work in seams down to 1 m (40 in.). The final design choice was between a linear and a rotary tester. The rotary tester would cut on an arc in the same manner as a rotary drum machine. It had several faults, however, that could not be resolved within the scope of this contract. The worst was related to arc cutting (Roepke, Lindroth, and Myren, 1976). Since any bit cutting on arc enters the coal at zero depth, goes to maximum depth only at the horizontal centerline, and exits at zero, maximum cutting force is obtained only at the instant the bit crosses the horizontal centerline. This centerline peak response would require that many replications be made with an arc-type cutter to get reliable force information. The arc-type tester would require extensive face preparation to establish the cutting path and extensive wasted clearing cuts to advance the device for additional layers of cuts. The linear tester could be mounted directly on any face or rib with only minor preparation. By its nature, a linear cut at a constant depth provides multiple peak force data over the length of the cut, thus reducing the required number of replications. The final review of these two major design concepts plus indus-

Jan 9, 1983

By M. J. Hannan

Considerable interest has arisen in developing analytical methods suitable for measuring resource commodity substitution patterns. some of this work has applied the Translog method to estimate actual elasticities of substitution. Recent examples incl.uae Privolos and Dunietz (1987), Kopp and Smith (1983), and Moroney and Trapani (1983). Another method, one which has received attention earlier in the work of Fisher and Pry (1970), is that of the logistic or diffusion function. We believe that the latter method has properties suitable for analyzing current problems of material substitution. The present study thus evaluates this method in its original logistic form as well as an extended version incorporating additional explanatory influences. The analysis is applied to copper/aluminum substitution and iron ore beneficiation. Substitution for copper by aluminum is examined in the building wire and cable, and magnet wire end-use markets. For iron ore, the substitution of pellets for sinter is considered for the U. S. market.

Jan 1, 1990

By H Kurth

Mining geologists utilise many technologies to map, sample, measure, model and plan before and during the mining process. Predicted ore quality rarely corresponds with feed quality determined by process operators. Objectively measuring conveyed material quality accurately in real time avoids disagreements over mined ore quality and generates opportunities to improve mill feed quality.This paper discusses the well proven PGNAA (prompt gamma neutron activation analysis) technology used in the GEOSCAN-M elemental analyser that is ideally suited to measuring composition of primary crushed conveyed material in real time. Representative, continuous, fully penetrative measurements are unaffected by particle size, belt speed, mineralogy, dust or layering on the conveyor. Material can be directed to processes or stockpiles by utilising measurement increments of typically one to five minutes and then activating diverters to direct increments to the correct location. Waste, low-grade or deleterious material can be rejected to waste dumps or stockpiled for later processing. Material meeting a product specification can bypass unnecessary processing. Paybacks in weeks have been achieved for such applications. Process operators are able to control the blend of ores fed into the mill to improve processing performance and use measurements for ore reconciliation and metal accounting. Utilising the technology to upgrade ore quality after mining and before processing is beneficial in improving plant economics.The technology has been successfully utilised in base metals, ferrous metals and industrial minerals. Mining geologists can determine ore quality being produced in real time and modify the ore quality prior to milling. Ore feed quality measurements are also used by process operators in optimising plant performance. The elemental content can help identify geometallurgical domains as well as other major changes in quality, which may affect processing. This paper outlines proven applications and case studies and proposes some innovative applications.CITATION:Kurth, H, 2017. Measuring ore quality using real-time on-belt elemental analysis – more than grade control, in Proceedings Tenth International Mining Geology Conference 2017, pp 213–220 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 20, 2017

By T. R. Kostecki, K. V. Jessu

"Roof bolts are subjected to axial stresses, shear stresses, or both. Axial and shear stresses were compared between roof bolts machined with two and three slots. Shear stresses perpendicular to and at an angle to the shear planes were evaluated by analyzing a three-slot instrumented roof bolt, performing laboratory tests on two- and three-slot roof bolts, and conducting in-situ test analyses. Threeslot bolts appear to provide a complete bending strain profile, requiring no prior knowledge of the estimated shear-plane orientation. Minimum displacements occur in roof bolts installed perpendicular to rather than at an angle to the shear planes.RÉSUMÉ Les boulons d’ancrage dans le toit d’une mine sont sujets à des contraintes axiales, des contraintes de cisaillement ou les deux. On a comparé les contraintes axiales et de cisaillement de boulons d’ancrage usinés avec deux ou trois fentes. Les contraintes de cisaillement perpendiculaires et à angle aux plans de cisaillement ont été évaluées en analysant un boulon d’ancrage de toit à trois fentes, en effectuant des essais en laboratoire sur des boulons d’ancrage de toit à deux et à trois fentes et en effectuant des analyses de tests in situ. Les boulons à trois fentes semblent fournir un profil complet de résistance aux contraintes de flexion, sans avoir besoin de connaître l’orientation estimée du plan de cisaillement. Des déplacements minimums ont lieu dans les boulons d’ancrage de toit installés perpendiculairement, plutôt qu’à un angle, aux plans de cisaillement."

Jan 1, 2016

By S A. McManus

With the advances in software speed and capability, many of us now are running multiple scenarios on entire models rather than just testing small areas or a few blocks. In the authors experience both the geological and geostatistical academic theory and our rules of thumb, often prove un-useable or incorrect in the real world we work in. The only way to truly validate and tune our models is to complete the entire model and ‘see if it works’. If it lacks some property we were expecting, then we need to find out why and/or run different scenarios to see what changes. This is not always possible with tight project timelines but we find ourselves doing more and more of this sort of thing, and in so doing, understand that every deposit is different and requires its own ‘rules’ to get valid and useful results. For the purposes of this paper, this process is termed Empirical Geostatistics. Take Clayton Deutsch’s ‘all realisations all of the time’ concept a step back. Before you even think of simulating, test the alternate realisations generated by alternate parameters such as different domaining, varying search neighbourhood parameters etc.

Mar 22, 2022