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By M. Doucet

The introduction of high-nickel anodes to CCR in 2006 resulted in an increase of nickel in anodic slimes. Removal of the nickel in these slimes to below 3.0% is necessary in order to prevent slag viscosity problems in the subsequent pyrometallurgical step. A lower specification of 0.5% was chosen in order to minimize Ni losses to the slag and to recover this nickel as NiSO4. A 2-stage autoclave process, which was patented by CCR in 1992, was chosen to treat the high nickel slimes. Laboratory and plant?scale tests were performed in 2004 in order to validate the results of this process with the present slimes. These results along with corrosion tests were used to design two brick-lined autoclaves. These autoclaves were installed in October 2006 and successfully commissioned within 8 weeks. A "Design of Experiment" test program was performed in 2006 on an alternative autoclave process that reversed the cycles in the patented process. The effects of temperature and acid content were modeled using the results. The alternative process will be validated with the new autoclaves.

Jan 1, 2007

By G. Shaw

IN recent years, most of the reconnaissance work of the Geological Survey of Canada has been mapped on a scale of 1 inch to 4 miles. Topographic base maps, commonly made from aerial photographs, were available to the geologist for such work. The advent of war curtailed aerial photography for civilian purposes, and by 1941 all areas already photographed had been geologically mapped. Nevertheless, the need for geological maps to assist post-war prospecting was so apparent, and the country to be covered is so vast, that some new method of rapid mapping had to be devised. It was felt that the need would be met if geological maps could be produced at a scale of 1 inch to 8 miles, provided they were sufficiently accurate in topographic detail to serve as guides to travel. Though in such maps there would be considerable sacrifice of geological detail, they would serve to outline, at least approximately, the major geological units, some of which might prove of sufficient interest to warrant later detailed study. It seemed that such mapping would be particularly useful in the northern regions of Canada which the work of early explorers has indicated are underlain largely by granitic rocks. These, so far as is known, are barren of mineral deposits, but within them are known to be areas or bands of 'greenstones' of the type that, in some localities, have been found to contain valuable orebodies. The problem, then, was to devise a method of mapping, particularly of such greenstone bands, that would make it possible to cover a relatively large area-say 30,000 square miles-in one season and at a cost below that of 4-mile mapping, with, of course, some sacrifice of accuracy. The problem seemed to be threefold: (a) to observe as much of the bed-rock as possible; (b) to produce a topographical map of as much of the area as possible, with particular reference to portions of geological interest; and (c) to cover as large an area as possible in a limited time, which meant faster modes of travel than have hitherto been used. The obvious answer to all three phases of the problem was the use of aircraft. If rock types could be broadly differentiated from the air, reconnaissance traverses by air would supply the answer to the first part of the problem. For topography, air photographs taken on reconnaissance flights appeared to be the answer. For the third phase of the problem, the use of aircraft was ideal.

Jan 1, 1943

By K. Spence

"The notion of “value” has always been a subjective and contentious issue. Indeed, value is in the eye of the beholder. There are as varied methods and practices for valuing property, as there are industries in which they are applied. For example, there is replacement value, insurance value, salvage value, appraised value, book value, and fair market value, to name a few, although in the mining industry, valuations usually refer to fair market value.In the Canadian mining industry, at present, there are no comprehensive regulations or guidelines that specify which approaches or methods are appropriate for use in the valuation of mineral projects. In January 1999, The Mining Standards Task Force of the Toronto Stock Exchange and the Ontario Securities Commission recommended that the Canadian Institute of Mining, Metallurgy and Petroleum (CIM) establish a committee to review and advise on approaches and methodologies for the valuation of mineral properties. Among the approaches to be considered are included the following: the discounted cash flow approach, the cost approach, the option pricing approach and the market comparables approach. In addition, methodologies differ depending on whether the project is at the exploration stage or the producing stage.The CIM Special Committee on the Valuation of Mineral Properties (CIMVal) expects that its final report will form the basis for a Canadian code or standard for the valuation of mineral properties."

Jan 1, 2002

By M. Boher, J. Lehmann, M. C. Kaerlé

"In the production of high quality steel, the understanding of the interactions between liquid steel and refractories and of their effect on steel purity and cleanness are becoming more and more important.An experimental study has been per-formed in order to estimate the importance of the reaction between a MgO-based tundish refractory and an Al-killed steel. The results show a pollution of the liquid steel:•the silicon content of the liquid steel increases due to the reduction of the silica of the refractory by the aluminum contained in the steel; and•a reoxidation of the steel occurs and the formation of an oxide layer on the refracto-ry, mainly composed of spinel crystals and of Ca-aluminates is observed.The transfer mechanisms of the various elements are analyzed."

Jan 1, 1997

By Charles J. Zablocki, Robert J. Kamilli

"Abstract - Buried, possibly mineralized granite cupolas at the Silsilah tin deposit in Saudi Arabia (lat. 26°06' N, long. 42°40' E) have been successfully located using a closely spaced electric-field-ratio profiling technique. In this study, electrical fields at 27 and 270 Hz across grounded electrodes spaced 50 m apart were measured along six traverses. This method is interpretable by inspection, unlike the dipole-dipole technique, which requires mathematical modeling for interpretation.In the study area, the technique allowed the authors to identify and distinguish among unroofed granite cupolas, cupolas with their aplite-pegmatite apical contact zones intact, strong (quartz-rich) and weak (relatively quartz-poor) greisens, dikes, faults, and pervasively argillized rocks.This method should be useful in the valuation of other shallow mineral prospects in similar settings in other parts of the world, especially deposits for which the location of vertical contrasts is important, such as veins or mineralized zones associated with the apexes of small igneous cupolas."

Jan 1, 1993

By K. Yamaguchi

To contribute highly efficient and environmentally conscious copper smelting process, several topics in chemistry of the continuous converting were discussed. Through the reviewing the authors' thermodynamic simulations, it is recognized that small amount and low copper content of the coexisting slag is preferable. Some discussions were added to the Takeda's diagram for Cu20-FeOx-CaO ferrite slag, and the activity curves of the constituents were derived. Thermodynamic calculations were carried out on the copper contents of the slag during the blister copper formation. The dissolution of copper in slag decrease somewhat with increasing temperature, but the effects of increasing S02 pressure and decreasing %S in copper are considerable to increase in copper content of the slag. The optimum oxygen enrichment in the supplied air, and regulation of the oxidation degree for the blister copper are important in practice. The gypsum phase separation in the calcium ferrite slag was also evaluated thermodynamically, and concluded that decreasing temperature, increasing CaO content or S02 pressure, and extensive oxidation of the blister copper tend to separate CaS04.

Jan 1, 2007

By A. Zarei-Hanzaki, S. M. Fatemi-Varzaneh, M. Haghshenas

The microstructure in modified semi-solid ALTHIX (A356) alloy consists of aAl phase with Al/Si eutectic structure. Silicon phase in eutectic structure is coral like with fine fibers. The lack of good ductility in this alloy is related to the presence of silicon fibers. Accordingly many investigations have been recently conducted to modify the Si morphology through Thermomechanical processing on this alloy. In the present work an ALTHIX (A356) alloy was deformed at 450°C, 500°C and 540°C through different strain rates. Consequently the silicon fibers were broken into small particles. The results indicated that the Si particles may coarsen according to Ostwald ripening mechanism at 540°C deformed by rate of0.0005 sec-1 & 0.0001 sec-1-

Jan 1, 2006

By C. H. Sleeman

"The Iron Ore Company of Canada constructed a beneficiation complex in Sept-Iles, Quebec, to concentrate and pelletize earthy red hematite iron ores from the Knob Lake area. The plants were scheduled for initial production during the first quarter of 1973.Many problems have been experienced to date. Difficulties in controlling the process, excessive mechanical failures, design deficiencies and manpower-staffing problems have caused an extended start-up. The problems are now essentially solved and, with the completion of some additional minor modifications, it is expected that the plants will be producing premium iron ore pellets at or near rated capacity within the next immediate period."

Jan 1, 1976

A mini- or micro-machine is a small electro- mechanical device. There are several existing applications of micro-sensors such as the accelerometers used in automobile airbags or the force sensors and grippers used at the ends of micro-surgery tools. Potential applications of existing mini- and micro-technologies are possible and could be used to improve the control and efficiency of fragmentation, heap leaching and other mining and mineral processing operations. A more radical proposition is to devise mass-produced, possibly disposable, minimachines that would operate in large groups. These would be the basis of highly selective, efficient, flexible, and clean mining and mineral processing methods. The paper is intended to promote discussion of how innovative applications of mini-technologies can be used to improve and radically change current mining and mineral processing methods.

Jan 1, 2002

By A. O. Sfriso

"Numerical modelling is becoming universal in rock engineering practice. Most applications focus on the prediction of failure loads of 2D problems, where the numerical models are useful extensions to analytical methods and experience-based design criteria. For 3D problems and problems where the assessment of serviceability indicators – displacements, ground-structure response, etc. – are of importance, the selection of the constitutive models themselves and the implications of the selection of material parameters may have a very heavy impact on the reliability of the model outcome and its predictive capability.This paper overviews basic common aspects of constitutive equations used in practical rock engineering and summarizes some challenges that are frequently observed when reviewing numerical models performed for routine problems in rock engineering. INTRODUCTIONNumerical methodsFrom a philosophical perspective models, either analytical or numerical, are idealizations of a perceived reality. For us engineers, models are just tools we use to guide our judgement and understanding of the problem in hand. When dealing with problems in rock engineering, we resort to a wide range of techniques:1. Closed form solutions like confinement-convergence methods for circular tunnels: these methods satisfy equilibrium and compatibility requirements at the cost of a crude simplification of the material behavior and geometry;2. Limit analysis methods, like bearing capacity formulas: lower bound methods satisfy equilibrium but sacrifice compatibility, and upper bound methods do the opposite. Material behavior must be simple, geometry admits limited freedom;3. Limit equilibrium methods, like method of slices for slope stability: they satisfy restricted forms of equilibrium, do not satisfy compatibility requirements, require simple material behavior but have a much greater flexibility on geometry;4. Numerical methods, where a mesh is employed to discretize the problem geometry: when properly formulated, these methods satisfy equilibrium and compatibility requirements and give reasonable approximations to the behavior of very complex geometries and construction sequences. Very little restrictions remain on geometry and material behavior, but the cost of calibrating the material parameters can be very high."

Jan 1, 2015

"Dry crushing trials at pilot scale have shown that the IMPTEC Super-fine Crusher has the capacity to generate ultra-fine products from hard mineral assemblages presenting at either coarse or fine feed sizes. The super-fine crusher was introduced at the 27th International Mineral Processing Congress in Santiago Chile, with results from a range of duties, which demonstrated the crusher’s potentially expansive operating scope. This paper focuses on current preparations to progress the technology from pilot scale to commercial scale within a concrete production plant, where lead blast furnace slag will be crushed to ultrafine sizes to generate an active silica product for use as a supplementary cementitious material, which can replace Ordinary Portland Cement. A key objective of the operation is to demonstrate an economical route to reducing the cost of concrete production, improving concrete quality and reducing greenhouse gas emissions. The paper also highlights the potentially key contribution super-fine crushing can make to the long-term viability of iron ore beneficiation by simplifying comminution flow-sheets and reducing operating costs. There is every indication that the technology has the potential to feature universally in metalliferous and industrial mineral flow-sheets. INTRODUCTIONToday’s IMPTEC super-fine crusher is the successful end product of development work over 19 years and is the third particle size reduction device conceived, built and tested over that time. The concept evolved as engineering design progressively developed a mechanism capable of harnessing a highly efficient combination of fundamental particle breakage mechanisms. Early development trials at pilot scale indicated that super-fine crushing had the potential to establish a wet or dry, media free, low energy route to ultra- fine products from hard mineral assemblages. Having achieved some impressive results from open circuit pilot tests on fly ash and granulated blast furnace slag it became clear that the cement industry may well provide opportunities to apply the technology commercially. Following expressions of interest from local cement and concrete plant operators, IMPTEC negotiated an agreement to undertake commercial trials with a SFC 350 super-fine crusher installed on site at a concrete supply plant in South Australia. Super-fine crushing scope was recently expanded following further expressions of interest from research groups involved in the processing of iron ores. Pilot trials are progressing in these areas."

Jan 1, 2016

By Azadeh Riahi

The main goal of this paper is to investigate the effects of permeability anisotropy in Large Open Pit (LOP) mines for problems that exhibit homogeneous anisotropic characteristics. The most important effect of the groundwater flow in open pit mines is on the stability of the pit slopes. This study will investigate the effects of having increased permeability in both horizontal and vertical directions on three aspects of LOP behavior, location of phreatic surface, pore pressure distribution and stability of slopes. The hydromechanical coupling is simulated using a one-way coupling approach. The Shear Strength Reduction method (SSR) is applied to assess the stability of slopes. The studies performed in this paper suggest that anisotropy in permeability leads to a significantly different regime of pore pressure dissipation depending on two aspects, ratio of anisotropy and the relative magnitude of permeability to simulated time. As a result, variation in safety factors and the location and depth of the failure surface must be expected.

Jun 1, 2012

By R. Kumar, A. K. Verma

"In this paper, an anisotropic shear behavior of rock joints is investigated under constant normal load condition (CNL). The natural rock joint roughness is transferred to artificial rock samples using room temperature vulcanizing (RTV) silicon rubber. Artificial cylindrical rock joint samples (90 mm diameter and 50 mm height) are made by mixture of cement, sand, and water in the ratio of 1:1.5:0.45 (by weight). Direct shear tests are conducted on these samples in twelve directions at 30º apart at four different normal stresses (250kPa, 500kPa, 1000kPa, and 1500kPa). Thus, 48 samples are tested in laboratory. Test results shows that the peak shear strength (?) of rock joints is anisotropic in nature due to change in morphological features in particular shearing direction. Joint roughness coefficient (JRC) is determined in each shearing direction by trial and error method using Barton’s model (1973). Further, cohesion ( c) and angle of friction ( ? )of joint surface in each direction is determined. Finally, a relationship between angle of friction ( ? ) and joint roughness coefficient (JRC) is developed. Experimental shear strength and Barton’s shear strength is compared and it is found that effect of anisotropic decreases with increasing normal stress. INTRODUCTIONRock mass is generally composed of discontinuity which refers collectively to joints, faults, bedding plane and folds etc. ISRM (1978) defined joint as a line of break of geological origin along which there is no visible displacement. Joint is three dimensional discontinuity which composed of two matched/mismatched surfaces. The presence of joints in rock mass plays an important role to define its overall shear strength, deformability behavior, in-situ stresses and hydro-geological properties. The shear strength of rock joints is important in the design of near surface/ deep geotechnical works (mining excavation, dam foundation, power plants, underground caverns, and slopes).In last 40 years, many constitutive models are developed to predict shear strength of rock joints under CNL conditions (Patton 1966; Landanyi and Archambault 1969; Barton 1973; Goodman 1976; Barton and Choubey 1977; Plesha 1987; Desai ad Fishman 1991; Amadei and Saeb 1992; Maksimovic 1992; Wibowo et al. 1993; Huang et al. 1993; Amadei et al. 1998; Indraratna 2000; Homand et al. 2001; Wang et. al. 2003; Samadhiya et. al. 2008; Asadollahi and Tonon 2010; Ghazvinian et al. 2012). These constitutive models have limitations to predict shear strength of rock joints in one direction. Till date, among all constitutive models, Barton (1973) model is widely used in practice due its simplicity. It includes parameters such as joint roughness and joint compressive strength (JCS) to quantify joint surfaces."

Jan 1, 2015

By P. P. Rosario

A research project was conducted at the University of British Columbia (UBC) resulting in the development and evaluation of a novel comminution circuit incorporating autogenous grinding and parallel trains of cone crushers and high-pressure grinding rolls (HPGR). A primary driver for the circuit was to treat ore from deposits with clay and variable hardness. This paper summarizes the unique pilot-plant test program that was developed as a basis for experimental simulation and lists the main findings of the research, including the circuit?s potential operational cost savings compared to a conventional SAG circuit.

Jan 1, 2012

By T. L. McCall

AUTHENTIC records show that coal mining in Cape Breton dates from the year 1720, when the French military authorities obtained coal from what is now known as the Blockhouse seam, in the Morien district, for use at Louisburg, where the fortress, now of such historic interest, was being built. Thereafter, coal was mined more or less continuously, and although, for many years, in a very haphazard way, there was, on the whole, a steady growth towards a better regulation of the industry, culminating in the year 1825 with the arrival of the General Mining Association in Nova Scotia. This Company, more generally known as the G.M.A., had acquired extensive tracts in Brazil and Colombia and had also purchased the mining rights for the whole of Nova Scotia-excepting such areas as had been previously leased-the attraction being the rich veins of copper currently reported as occurring in the Province. These fabulous copper veins, upon examination, failed to materialize, but the engineer sent out to report on them returned with such good accounts of the coalfields he had seen that steps were taken immediately to investigate them. From that rime onward, the history of coal mining in Nova Scotia is one of progress and achievement. One of the first acts of the G.M.A. was to acquire the areas already leased to other concerns and develop these in a masterly fashion, employing the best machinery and talent available at that time. Such dominant control over the minerals of the Province, although it led to orderly development in the several coalfields, also, later on, resulted in restricting operations in the various coal centres to such an extent that a determined effort was put forward by the people of Nova Scotia to end such a state of affairs. Consequently, in 1857, the original lease of the G.M.A. was abrogated, the Company, however, being allowed to retain certain areas in the districts it had already developed. This opened the way for the formation of other coal-mining companies, and numbers of these immediately sprang into existence in the various coal-mining centres. In 1893, the Dominion Coal Company, Limited, was formed by the amalgamation of seven companies operating in the neighbourhood of Glace Bay, in Cape Breton. Later, in 1910, the Dominion Iron & Steel Company, Limited, obtained control of the Cumberland Railway & Coal Company, which had been formed in 1884 to acquire the rights of the two companies working in the Cumberland County coalfield.

Jan 1, 1936

By M. S. Diederichs, J. Oke

Surface limitations and a need for more direct transportation routes require serious consideration be given to the development of underground construction works in geotechnically unfavourable conditions. Due to geographical and logistical limitations, the construction of these underground works is restricted to difficult ground conditions that require temporary pre-support before excavation in order to avoid tunnel collapse or severe surface settlement. One type of pre-support is the umbrella arch system, which has been gaining popularity due to cost and time commitment in comparison with other pre-support systems (e.g., ground freezing). The umbrella arch system has been employed with significant frequency around the world, yet without a complete understanding about the mechanical response of the system. As such, literature has found the temporary support system to be both under and over designed with regard to safety and/or economical impact. The authors of this paper have made three major contributions to increase understanding of the umbrella arch system and to help optimize the design process. Firstly, the authors have developed nomenclature in order to categorize and define umbrella arch elements and systems, which also stimulated the creation of the empirically driven Umbrella Arch Selection Chart. Secondly, the authors have established a design methodology that is primarily based on advanced numerical modelling techniques to aid in the optimized design of the umbrella arch arrangement for site specific conditions. Thirdly, the authors have developed a semi-analytical model for umbrella arch systems employed in squeezing ground conditions by incorporating elastic foundation theory as well as convergence confinement theory. These three major contributions to such a widely employed tunnelling pre-support system will be introduced and explained in detail, and will include discussion of how each is incorporated in the complete tunnel support design process and throughout the construction and monitoring phase of a project.

Jan 1, 2015

By A. G. Mattes

This paper presents an overview of passive, engineered, biologically-based anaerobic bioreactor (ABR) treatment systems of the sort that can be used to remove dissolved copper from mine wastewaters. The paper begins with a brief history of the origins of this treatment technology and continues with a discussion of principles of engineered wetlands (EWs, advanced kinds of constructed wetlands, CWs) and the use of vertical sub-surface flow (VSSF) varieties that contain pulp & paper biosolids as the reactive medium for EW cells. A brief outline of a procedural methodology used in evaluating the potential for biological treatment on a site-specific basis is also included. An introduction to the microbiology of passive biologically-based treatment systems is followed by some recent research results in the general area of wetlands and ABR research. The paper concludes with a brief discussion of several sites known by the authors to have successfully (or not) demonstrated the potential of this treatment option.

Jan 1, 2007

By R. T. Elworthy

Canada ranks second in the list of world consumers of natural gas. In 1923 our production was nearly fifteen million thousand cubic feet valued at $5,800,000. Our output, however, appears very small compared with that of the United States, which in 1923 totalled over one thousand and eight million cubic feet, valued at $240,000,000. Natural gas is found in commercial quantities in three? provinces in Canada. New Brunswick: Natural gas in New Brunswick has been utilized commercially only since 1912,although the investigation of oil and gas possibilities of the province commenced as early as 1859. The annual production is a little more than one-twentieth of the total Canadian production and remains fairly constant from year to year. Ontario: In Ontario the earliest gas wells were drilled in Essex and Welland counties between the years 1885 and 1890. On account of the small demand in Canada the cities of Detroit and Buffalo were supplied with large quantities of gas from these wells, but this export was curtailed in 1898 and finally ceased in 1900. The production of natural gas in Ontario, mainly from fields in Lambton, Kent, Essex, Norfolk, Haldimand and Welland counties, increased rapidly from 1900 until the peak was reached in 1917, when over nineteen million thousand cubic feet valued at $3,641,587 was consumed.

Jan 1, 1925

By B. S. Kim, Y. D. Kim, T. S. Kim, T. B. Kim, H. J. Chae

"The Nd-Fe-B scrap was placed in Fe crucible with pure Mg in an Ar atmosphere, and the scraps were melted using an induction heating method. The effects of experimental parameters such as melting temperature (range of 993K to 1073K) and holding time (15min-600min) on the ability of extraction were investigated. The microstructure and diffusion layers were analyzed by Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS), and the constituent phases were characterized using XRay Diffraction (XRD). Diffusion of Nd through the Nd-Fe-B scrap into liquid Mg was described, and the diffusion coefficient of Nd in liquid Mg was estimated.INTRODUCTIONNd-Fe-B magnets are usually produced either from comminuted melt-spun ribbons as bonded magnets or hot pressed bulk magnets, or by sintering in conjunction with prior green compaction in an applied magnetic field (Sagawa et al., 1984). These magnets have been widely used for various electromechanical and electronic devices such as voice coil motors (VCMs) and magnetic resonance imaging (MRI) (Samardzija et al., 2012; Matsuura et al., 2006). The production of the Nd-Fe-B magnets is increasing by about 20% per year because of their excellent magnetic properties. However, the expansion of Nd-Fe-B magnet market induced a concern for the scarcity of Nd at the aspect of natural resource. Therefore, the development of an effective recycling process for Nd-Fe-B magnet scraps is an extremely important issue from the viewpoint of resource and energy conservation. Several recycling processes for the Nd-Fe-B magnets have been proposed (Uda et al., 2002; Lyman et al., 1993]. It has been reported that the best separation of rare-earths from the Nd-Fe-B magnets is obtained by sulfuric acid dissolution followed by precipitation of recyclable rare-earth salts. However, this process can make a large amount of waste water including dangerous solutions. Recently, (Xu et al., 2000) have reported a technique to extract Nd from 18Nd-72.4Fe-0.9B-1.82Pr-5.3Dy (wt.%) magnet scrap by using liquid metal extraction (LME) processing. However, these techniques seemed to be difficult for application, because the scraps consist of an infinitesimal amount of other minor elements (Pr, Dy, Cu, Al and Tb), and these minor elements can make a new intermetallic compounds with Mg. Also, some oxides or the plated Ni metal can be preventable to reaction between solid-liquid (S/L) interfaces. For these reasons, the substantive reaction mechanism between Mg and Nd-Fe-B scrap is not clear. In this study, the simple composition of 33Nd-66Fe-1B (wt.%) magnet scraps were prepared using an induction melting process. The effects of the experimental parameter on the diffusion properties between Mg and scraps were investigated to determine whether these methods could be used in industrial application in a liquid metal extraction (LME) process."

Jan 1, 2012

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