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By A. D. Dalvi

Economics, Resources, Environment and Technology are the major driving forces in the base metals industry. However, these factors are intertwined and together will propel the industry in the future. The demand for metals has grown with economic expansion, between 2 to 4 % p.a. The current growth cycle has been driven by economic expansion in China where the demand for base metals has risen from - 7 % of the world demand in the 90's to - 25 % of world demand today, and rising. Base metals are commodities and their demand and price are cyclical. Historically metal prices have declined in constant dollars, forcing the industry to reduce costs, increase productivity and increase the scale of operation for economies of scale. Due to resource depletion and capacity expansion the industry is driven to expand its reserve and resource base. However, in the case of sulphide deposits of copper and nickel it appears to be a losing battle. For nickel the laterites represent a vast source at this time. Their development requires development of new technologies to make these resources economic. Emission reduction is being increasingly mandated in most jurisdictions with all governments enacting progressively more stringent regulations. The industry has been responding with technological innovation. With the Kyoto protocol there is a push to reduce energy intensity in metal production. Technological innovation is driven by all the other factors and is leading to novel ways of doing exploration, mining and processing, that would maximize resource delineation and utilization, reduce costs, increase productivity, reduce energy consumption, maximize asset utilization and reduce environmental affects. Development of alternative technologies such as Pressure Acid Leach of laterite for nickel, bio-leaching, heap leaching, SX-EW etc are being adopted to achieve the aims of the industry.

Jan 1, 2005

By M. E. Holuszko

A research program has been carried out at the Mining Department of the University of British Columbia to study the effect of wettability of coal on its handleability and bulk density. The effect of moisture content on the bulk density of coal was found to be more pronounced for hydrophilic coals than for hydrophopbic ones. Altering wettability of coal surface leads to different effects of moisture on bulk density. The samples were studied at different fine fractions content, and it was shown that there was no effect of increased content of fines on the bulk density for hydrophobic coals, while for hydrophilic coals this effect was very significant. It was shown that the moisture content at which the lowest bulk density was reached coincides with the critical moisture content for studied samples, as determined from handleability tests using Durham Cone method. This critical moisture is the moisture content at which a sudden deterioration of coal handleability occurs. Based on the bulk density and handleability tests, the flow theory of moist coal is proposed.

Jan 1, 2006

By D. M. Muir

The mineralogy of residues formed during the pressure acid leaching of arid region nickel laterite ore varies according to the salinity of the process water, alkali cation additives and the overall acid loading. In fresh water, hematite is the main iron-bearing leach residue component, together with amorphous silica and hydronium or sodium alunite/jarosite [(H3O,Na)(Fe,Al)3(SO4)2(OH)6]. As the process water salinity increases, or as NH4+ or K salts are added, alunite/jarosite is the kinetically favoured iron-bearing phase accompanied by an increase in acid consumption. The alunite/jarosite appears as two XRD distinct phases with different Fe:Al molar ratios. In weakly saline water, iron-rich alunite/jarosite slowly transforms to hematite and an aluminium-rich alunite/jarosite together with the release of acid. The addition of potassium salts forms a more stable alunite/jarosite whilst the addition of ammonium salts leads to greater transformation of alunite/jarosite at 250°C. Weakly saline process water gives enhanced nickel recoveries, whilst strongly saline process water gives lower nickel recoveries but higher soluble iron because of chloro-complexation. SEM and microprobe analysis shows very little nickel is associated with the alunite/jarosite and hematite phases. Nickel losses to the residues are attributed to adsorption on amorphous silica and to a lesser extent on alunite/jarosite.

Jan 1, 2006

By Ralph L. Rutherford

Geologists or mining engineers familiar with geology are frequently requested by mine operators to give correlation in-formation regarding some mining property with respect to an adjacent area on one at some greater distance. It is the object of this article to mention a few of the difficulties involved in securing this information and to point out some of the salient factors upon which correlation is dependent. In view of the nature of the following discussion, a brief statement of the general character of coal formations .. seems appropriate. Coal formations, by reason of their environment of deposition which is in fresh or brackish water, exhibit the features common to continental deposits, in contrast to those of marine deposits. Such deposits are characterized by rapid variation in thickness and in lithological character both later-ally and vertically. (Plate 1 A). They consist essentially of sandstones and clay shales with all gradations between them, and also a few beds of coal and frequently some conglomerates.

Jan 1, 1924

By Barry D. Simmons

"A well-defined approach is essential to ensure the long-term success of a regional exploration program. Teck's approach in eastern Canada is designed to fulfill corporate objectives while recognizing certain unique parameters for exploration in the area. The elements of this approach include clearly defined objectives, technical considerations and personnel policies, all of which are equally important. The goal is a significant discovery before the mid-l990s and the company is confident that this target will be achieved.IntroductionAs one of Canada's oldest continuously operating mining companies, Teck Corporation traces its roots to Kirkland Lake, Ontario, with the development of the Teck-Hughes gold mine in 1913, later supplemented by production from the Lamaque gold mine in Val d'Or, Quebec. Control of the company was acquired by Temagami Mining Company, part of the Keevil Mining Group, in 1959. Credited as one of the first discoveries made using airborne geophysics, the Keevil Group had recently found the small but very high-grade copper deposits at Temagami, Ontario. These developments in eastern Canada formed a foundation for remarkable growth and Teck's present status as one of Canada's most successful and respected mining companies.Teck currently operates successful mining ventures across Canada and has international exposure through its association with Cominco Ltd., M.I.M. Holdings Limited and Metallgesellschaft AG. Operations in eastern Canada, however, remain an important component of Teck's ongoing success. The David Bell and Williams mines at Hernlo, Ontario, are Canada's lowest cost and largest gold operations, respectively. The Niobec Mine at Chicoutimi, Quebec, is North America's only significant producer of niobium. Teck maintains a 45070 interest in Golden Knight Resources Inc., part owner of the successful gold mining operation in the Casa Berardi area of northwestern Quebec. As a significant shareholder in Aur Resources Inc. and as a part owner, Teck is participating in the development of the Louvicourt deposit, a major base metal discovery at Val d'Or, Quebec."

Jan 1, 1992

By Josée Dartois

En 1988, à l?instar de plusieurs états du monde industrialisé, le Québec décidait d?accélérer la cadence de l?assainissement des rejets industriels et lançait un programme intégré de réduction de la pollution industrielle visant, à la fois, les rejets dans le milieu aquatique, les émissions atmosphériques et les matières résiduelles. Ce programme fut intitulé le Programme de réduction des rejets industriels.

Nov 1, 2002

By F. H. Samuel, A. M. Samuel, H. R. Ammar

Casting imperfections, such as porosity, in cast aluminum components greatly influence their fatigue properties. The effect of porosity on the fatigue life of 319-F and A356-T6 aluminum alloys was studied, where the porosity characteristics on the fracture surfaces of fatigue-tested samples were examined using SEM and image analysis. The results show that porosity has the most detrimental effect on the fatigue life: 92 % of all tested samples fractured due to porosity acting as the main crack initiation site. In the absence of casting imperfections, other microstructural aspects such as slip bands can be responsible ( 4 % ). The porosity was investigated in terms of the pore size at the sample fracture surface and its location i.e. near the edge or close to the interior. It was found that porosity located far from the sample surface (edge) has less influence on the fatigue crack initiation, and the fatigue life decreases as the size of the pore located at the sample surface increases. Aluminium

Jan 1, 2006

By P. J. Le Roux

"Mining worldwide and definitely in South Africa, is constantly under pressure to reduce its cost structure so as to sustain profitability. In underground gold mines where an open stope mining method is employed, dilution often has a significant effect on the viability of sustaining profits. Target Mine practices Open Stope mining Method and it was found that in some open stopes dilution was in excess of 10%, which has a significant impact on the sustainability of the mine.Dilution in excess of 10% can result in the reduction of the recovered grade from 5,5 to 4,5 grams per ton (g/t). The reduction of 1 g/t in recovered grade results in a potential loss of about ZAR21 Million per month bases on a gold price of ZAR240 000 per kilogram. Based on Life of Mine projections the potential loss of income could be as much as ZAR3,3 Billion. A reduction in dilution would have the opposite effect. There are a number of factors which affect dilution of which falls of ground in open stopes is a major contributor. The falls of ground can be attributed to a number of factors such as beam failure as a result of a larger than normal expected roof area (hydraulic radius too large), poor ground conditions, and poor blasting. The cost of damage to or loss of trackless equipment as a direct result of the falls of ground in open stopes, is very significant. The review of financial figures has indicated that this could be as high as ZAR491 million. This combined with the added cost of transport, hoisting, secondary blasting, milling and plant treatment costs of ZAR293 results in an estimated opportunity loss of ZAR784 million.Currently there is a significant amount of data available in the mining industry which could be effectively used to develop suitable back analysis techniques but to date this has not been used effectively. If dilution can have such an impact on current and future mining ventures then the optimization of back analyses for the prediction of dilution in open stoping could assist significantly in the reduction of dilution in massive open stopes. Rockmass classifications, geotechnical information, blast techniques, blast design, the stress strain environment and hydraulic radius all have an effect on, or play a role in the evaluation of dilution. Each of these factors will be taken into consideration to ultimately determine a measurable or calculated percentage of dilution in massive open stopes.The amount of overbreak in an open stope can be determined by subtracting the planned stope volume in m3 from the actual measured final stope volume in m3, which is obtained from the CMS (cavity monitoring system). This is in turn divided by the planned stope volume in m3 to determine the percentage overbreak. The CMS wireframe is imported into the geological model and its grade re-evaluated. From this the actual percentage dilution for this open stope can be determined. The dilution obtained can result in a major reduction of recovered grade for the open stope, but can also increase the recovered grade. The latter is normally the exception rather than the rule.When analysing data from Target mine the following was achieved:• Using 11 years of data a method of measuring and predicting the percentage dilution in open stoping was developed. This took into account rock mass quality, stress-strain state, and the hangingwall hydraulic radius (size of stope hangingwall exposed).• Implementation of this prediction method resulted in a reduction in falls of ground in open stopes. The benefit of this was a reduction in the damage to mechanised equipment resulting from less falls of ground which had a positive effect on the profit margins of the mine. As a direct result the recovered grade from the open stopes increased due to the reduction in the amount of dilution.• A design criterion, Dilution Stress-Strain Index (DSSI), was developed which allows the user to calculate, with certainty, the stability of the open stope and determine if m"

Jan 1, 2015

By A. S. Dawson

"IntroductionTHE PURPOSE of this paper is to describe the results of a preliminary investigation of a method thought to be useful in interpreting geological structures in un-metamorphosed sedimentary rocks. The writer is not aware of the method having been described or investigated previously, although no thorough search of the literature has been made.The method to •be described is based on the assumption that, in argillaceous sedimentary rocks, certain ceramic properties are diagnostic for certain beds within areas of variable limits.Two ceramic properties• have been investigated: pyrometric cone equivalent (P.C.E.), and bloating characteristics of shales. The enquiry has been directed toward testing the usefulness of these properties in determining the following:A -The correlation of shale beds and, by inference, of coal seams, sandstone beds, or other such structures associated with them.B.-The location of contacts between marine and non-marine shales where lithological, palaeontological, or other evidence is lacking.Limitations of time and facilities have prevented a thorough investigation of this problem. The results given in the present paper are preliminary only. It is hoped, however, that they will occasion discussion or even lead to more thorough investigation of the method by individuals or organizations.There are, admittedly, various limitations to the proposed method. It is thought to show some promise when used in conjunction with the well-known and established methods used in stratigraphic correlation and, more particularly, when the conventional methods are not applicable."

Jan 1, 1952

By W. L. Goodwin

Twenty-five years ago mining engineering in Canada was not a profession. To-day the members of the mining fraternity can fairly claim for 10themselves the professional status. If their pretension is not fully warranted by fact it is not for lack of any technical attainment or service to the public but by reason merely of their neglect to cultivate the cohesion and consciousness that are the outward and visible signs of a professional body. This paper is an attempt, first to sketch briefly the course of the events during the past thirty-five years that have resulted in organizing the mining industry of this country in its present form; then to notice the principal features of the professional organization of this day; and finally to point out that an important part of the work of the mining engineer remains in the state of chaos that characterized the whole of it three or four decades ago, and to suggest a remedy. Thirty years ago there came a great wave of interest in mining in Canada, based principally upon the discovery of gold-quartz and gold-copper throughout wide areas in Nova Scotia, Ontario and British Columbia.

Jan 1, 1926

By W M. Gilchrist

This paper gives an estimation of the future requirements of the western world in relation to energy re-sources. It then goes on to outline the role that atomic power -with its basic raw material, uranium -will play in supplying these energy requirements. Canada's position in this picture is covered, and some interesting forecasts are made. Introduction I T is possible that the following remarks will appear to have more to do with power than uranium. However, to fully comprehend what is in store for the Canadian uranium mining industry, we must be able to estimate the potential requirement, and, to do this satisfactorily, a thorough understanding of the circumstances that will give rise to that demand is necessary. The growing need for electrical energy will play by far the major role, as large tonnages of uranium will be required for its generation. The nuclear weapon has, up to the present, comprised the major market for uranium.

Jan 1, 1964

By MAX VOS

Lithium is the lightest and electrochemically most reactive of all metals. Renewed interest in lithium coincides with research in lithium batteries and power generation by atomic fusion. Ontario lithium resources are contained in spodumene pegmatites that can form where medium- to high-grade metamorphic volcanic-sedimentary formations are intruded by pegmatite and porphyritic granitic rocks. Spodumene pegmatites occur in at least twelve locales throughout northern Ontario, all of which are in the Superior Province of the Precambrian Shield. Tantalum, cesium, rubidium, beryllium, niobium and tin also were noted with lithium in spodumene pegmatites. Considerable potential remains for discovery of additional lithium and rare-element pegmatites in northern Ontario.

Jan 1, 1984

By M. R. Khalesi, S. Bellec, C. Bazin, D. Hodouin

Batch grinding tests conducted on a gold ore indicated that gold is not randomly distributed within the size fractions of the ground ore. Since gold leaching performances were found to be dependent of the size of the gold carrying particles an integrated gold ore grinding-leaching simulator should incorporate a method to predict the gold size distribution of a ground ore. The paper describes the results obtained from batch grinding tests showing the non random distribution of gold within the size intervals of a ground ore and the initial developments of a grinding model to predict the gold size distribution in a batch grinding product.

Jan 1, 2011

By D. D. Macdonald, G. Engelhardt

The accumulation of damage due to localized corrosion [pitting, stress corrosion cracking (SCC), corrosion fatigue (CF), crevice corrosion (CC), and erosion-corrosion (EC)] in complex industrial systems, such as power plants, refineries, desalination systems, etc., poses a threat to continued safe and economic operation, primarily because of the sudden, catastrophic nature of the resulting failures. Of particular interest in managing these forms of damage is the development of robust algorithms that can be used to predict the integrated damage as a function of time and as a function of the operating conditions of the system. Because complex systems of the same design rapidly become unique, due to differences in operating histories, and because failures are rare events, there is generally insufficient data on any given system to derive reliable empirical models that capture the impact of all (or even some) of the important independent variables. Accordingly, empirical models have generally failed to provide a robust basis for predicting the accumulation of corrosion damage in complex systems under realistic operating conditions. The alternative prediction philosophy is determinism, in which the development of damage is described in terms of valid, physico-electrochemical mechanisms with the output being constrained by the natural laws. The differential damage is then integrated along the corrosion evolutionary path for the system (i.e., over the future operating "history") to yield the desired integrated damage, which is the quantity that is most useful to an operator. In this paper, we review the theory of predicting corrosion damage within the framework of Damage Function Analysis (DFA), with particular emphasis on the pitting of aluminum in chloride solutions and on the accumulation of damage from SCC in Type 304 SS components in the primary coolant circuits of Boiling Water (Nuclear) Reactors (BWRs). These cases have been selected to illustrate the various phases through which localized corrosion damage occurs.

Jan 1, 2005

Pilot plants for pressure hydrometallurgy represent special design and project execution challenges unique to the industry and to the pilot- and demonstration-scale. Pilot plant projects have different objectives and shorter timescales than commercial plant projects. Design considerations and strategies, and project execution methods that meet the special needs of pilot plant projects, are discussed. Specific guidance is given for the selection of appropriate pressure and temperature design points for pressure hydrometallurgical process equipment, and for the selection of materials of construction for pilot-scale equipment. The balance between the need for process similarity with future commercial operations and the realities of pilot-scale equipment is also discussed.

Jan 1, 2004

By E. Henderson, L. K. Daneshmend

Drawpoint control is critical in determining the cutoff point for load-haul-dump mucking operations to minimize dilution. It is also necessary to ensure even mucking distribution and to prevent possible hang-up of material within a stope. A prototype production monitoring and reporting system has been developed for load-haul-dump operations in under-ground mines. The system generates accurate and timely information regarding mucked tonnages and drawpoint and ore/waste pass utilization. The monitoring system integrates a PLC-based load weighing system with a radio frequency identification (RFID) system for locating the vehicle. The system records the identification and time of entry and exit of each draw-point and ore/waste pass visited during a shift, as well as the weight of each bucket load. A trial of the system was conducted at the CAN-MET Experimental Mine near Val d’Or, Quebec. The monitoring and reporting system functioned as designed, with the exception that the maximum read range of the RFID tags under dynamic conditions was found to be a limitation. RFID systems with greater range capabilities have been identified for a second generation system. The system is the first of its type in North America to demonstrate that RFID tagscan be successfully applied to locate trackless underground equipment. Because of their ability to locate equipment and personnel within underground mines, RFID systems should be considered a key technology for future mine information and process control systems.

Jan 1, 1996

By Shek N. Lau, Nicola Samman

"Enclosed gear cases on board heavy mining equipment have traditionally been lubricated with regular heavy duty gear oils. However, equipment manufacturers, have recommended the use of an ISO-1000 gear oil for this application to ensure adequate lubricant film strength, especially at the higher end of the working temperature range. The majority of these ISO-1000 gear oils are based either on residual/asphaltic oil or synthetics, primarily higher viscosity polyalphaolefins. Although the performance of these lubricants has been satisfactory, they suffered other shortcomings that equipment users have lived with over the years.The major requirement at the user’s mine was to provide lubrication for the shovel Hoist gear case. Within such a gear case design, the gears and the roller bearings, that have different lubrication requirements, are lubricated with the same lubricant. Several lubricants were used, light gear oils as well as the recommended ISO-1000 heavy gear oils. On the one hand, the lighter oils performed adequately for the lubrication of the bearings that formed part of the enclosed gear system. These lighter oils did not perform as well for the lubrication of the gears due to their lower viscosities, resulting in shorter gear servicelives.On the other hand, the ISO-1000 gear oils performed well for the lubrication of the gears, but were too viscous to creep into the bearing elements to lubricate them adequately, especially during the cold northern Canadian winters. This resulted in catastrophic bearing failures and secondary damages to the gears.The challenge, then, was to formulate a lubricant which met the 1000 cSt at 40°C viscosity requirement as stipulated by the equipment manufacturer, while satisfactorily lubricating the bearings at the full working temperature range. This was achieved by the development of a semi-fluid grease lubricant, which has proven in field trials to give adequate performance in this application for the lubrication of both the bearings and gears down to -40°C.This product met the equipment manufacturer’s performance criteria and resolved, to a large extent, leakage of the lubricant through seals experienced with the use of conventional and synthetic gear oils.Although the main performance criteria of the fluid was its capability to lubricate the “Hoist” gear case, it was also used during the field trial in other gear cases on board the shovel to test its full capabilities.This unusual alternative lubricant was field tested and evaluated for more than two years. Based on this assessment, the product was reformulated to improve its fluidity, slumpability and the settling of debris/wear metals to the bottom of the gear cases. This reformulated softer grade, a semi-fluid grease, has been performing satisfactorily for more than eight months and is still undergoing longer term assessment."

Jan 1, 1996

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 M. Sahoo, P. Burke, Y. Fasoyinu, J. P. Thomson

The effects of grain refinement, mold temperature and chemical composition on the hot tearing resistance of aluminum alloys 535.0 and 206.0 has been studied by pouring constrained rod castings in metal molds. In addition, two prototype components that could be used in automotive applications were also poured from both alloys by gravity tilt-pour and low pressure permanent mold casting processes. This paper summarizes the results and issues encountered during the casting trials. It was shown that grain refinement and mold temperature ::::: 400°C reduced, and sometimes eliminated hot tear cracks in both alloys. The two prototype engineering components could be cast successfully from both alloys in metal molds. The metallurgical issues related to molten metal treatment and processing temperatures were well controlled. However, issues related to the control of hot tearing, casting and mold design must be addressed in future studies to guarantee the production of defect free castings.

Jan 1, 2006

By S. F. Guo, B. W. Zheng, X. L. Huang, S. W. Qi

"The study of mechanical characteristics of rock discontinuities under different shear deformation velocities is an important premise of rock slope dynamic response analysis. According to disposing and calculating the experimental results of previous research about peak shear strength of rock discontinuities under different shear deformation velocity of constant normal loading, the law of influence of shear velocity on the total friction angle is studied. Based on the research results, it can be found that the total friction angle of rock joint specimens varies in the form of negative logarithm with the variation of shear deformation velocity. It’s also indicated that the total friction angle of rock joints decreases with the increase of shear deformation velocity for rock joints of relative strong homogeneity and isotropy. However, the total friction angle of rock joints increases with the increase of shear deformation velocity for rock joints of relative strong heterogeneity and anisotropy and the latter amplitude of increase is less than the former amplitude of decrease. The physical property and microscopic geometry of rock joints play an important effect on the increase or decrease tendency and amplitude variation of total friction angle with the increase of shear deformation velocity.INTRODUCTIONThe rock slope dynamic response is largely restricted by rock discontinuities. Hence the study of dynamic characteristics of rock discontinuities, especially the dynamic shear characteristics is an important premise of rock slope dynamic response analysis (Qi et al., 2007). Seismic load is both dynamic load and cyclic load (Liu et al., 2011). Under the dynamic and cyclic shearing actions of seismic load, the rock slope which is stable under the condition of static load may slide along the rock discontinuities whose shear strength reduce and then the earthquake landslides occur. The strength degradation and deformation mechanism of rock discontinuities under the dynamic and cyclic shearing actions is one of the key problems to be solved in the work of earthquake prevention and control of engineering slope. Based on the above understanding, predecessors conduct some researches which focus on the shear behavior mechanical characteristics of rock joints under cyclic shearing actions (Plesha, 1987; Hutson & Dowding, 1990; Jing et al., 1992, 1993; Huang et al., 1993; Qiu et al., 1993; Homand et al., 2001; Lee et al., 2001; Jafari et al., 2003; Liu et al., 2011, 2013). However, there are a few researches about the mechanical characteristics of rock joints under different shear deformation velocities because of the restriction of shear apparatus. Crawford and Curran (1981) conducted a series of one-way cyclic direct shear tests on four kinds of natural rock joints under different shear deformation velocities varying from 0 to 200 mm/s. The tests showed that at low normal stresses the peak shear strength of soft rock joints exhibited an increase up to a certain velocity, after which it remained essentially constant. For rock joints of intermediate hardness, the peak shear strength was essentially independent of shear deformation velocity; whereas for hard rock joints, the peak shear strength of which showed a significant variation with the shear deformation velocity. Jafari et al. (2003) carried out a series of conventional triaxial tests on artificial rock joints of regular saw-tooth shape with axial loading rate from 0.05 mm/s to 0.4 mm/s."

Jan 1, 2015