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By Stephen Hardcastle

Supplying ventilation in underground metal mines can be one of the most energy demanding services required to support production activities. Consequently, as energy, in the form of electricity or combustible fuels can be expensive and their unit cost is expected to increase, there is significant interest in reducing the overall demands of a mine?s ventilation system through such initiatives as controlling ventilation based upon demand and exploring other power alternatives to the current usage of the diesel engine in mobile mine vehicles. However, determining the benefit of any energy saving technology is complex and not universal applicable across the industry, consequently they have not been widely adopted. For these technologies to succeed they must be strategically applied based upon sound business cases. The intent of this paper is to provide information on some of the prospective control strategies and their potential impact on the power consumption related to supplying ventilation.

May 1, 2007

By J. L. Jambor, E. J. Reardon, E. C. Appleyard, J. A. Cherry

Abstract- Since the 1957 initiation of deposition of mill tailings at the Heath Steele mine, New Brunswick, periodic detailed studies of the tailings geochemistry and mineralogy have been con­ ducted, thereby providing a unique opportunity to examine the geochernical evolution of a sulfide- rich mine-tailings impoundment. When deposited, the tailings contained about 85 wt% sulfide minerals, 1 wt% to 3 wt% carbonate minerals, and 12 wt% to 14 wt% aluminosilicate minerals. Mineralogical examination of samples of the tailings from deep in the impoundment indicates that little oxidation occurred prior to tailings deposition. The mill process-water deposited with the tailings was neutral to slightly basic and contained low concentrations of Cu, Pb, Zn and As. Sampling of the tailings five years after deposition indicated that sulfide-oxidation reactions, occurring near the tailings surface, had decreased the tailings-water pH and increased the concentrations of Fe, SOi-, Cu, Zn and Pb (up to 10 000 mg/L, 25 000 mg/L, 2.5 mg/L, 200 mg/L, and 4.5 mg/L, respectively) . In 1975, ten years after decommissioning, the tailings could be divided into three zones: an upper oxidation zone in which sulfide oxidation is actively occurring, a hardpan layer, 15 cm to 20 cm thick, composed of tailings cemented by secondary Fe minerals, and an underlying reduction zone in which the tailings are relatively tinoxidized (Boorman and Watson, 1976). Chemical analyses indicated the presence of low-pH waters containing very high concentrations of SO42- , Fe, and other metals (up to 63 600 mg/L SO42-, 28 600 mg/L Fe, 10 mg/L Pb, 600 mg/L Cu and 4000 mg/L Zn), suggesting that there was a period of intense sulfide oxidation between five and ten years after tailings deposition. More recent sampling, conducted some 20 years after the end of tailings deposition, indicates that relatively little change has occurred in the last ten years, thereby suggesting that the hardpan layer has provided an impediment to the downward movement of dissolved constituents . Analyses of the tailings solids show increased accumulations of many metals at or near the depth of the hardpan layer. Evaluations of the long-term evolution of the tailings can be enhanced by comparison of descriptions of the tailings with descriptions of the gossan that overlay the massive­ sulfide orebody prior to mining. At Heath Steele, this comparison suggests that many of the mechanisms controlling the distribution of metals in the tailings will probably persist over geologic time.

Jan 1, 1992

By N. Gharib, F. Hassani, P. Nekoovaght

"Novel rock breakage techniques are becoming more viable and attractive to industry. Microwave energy, as a thermal energy capable of inducing micro cracks through differential heating (therefore expansion) is a technology gaining considerable attention in mineral processing and ore comminution applications. Recently, the use of microwave radiation has been evaluated as a possible avenue for terrestrial and extra-terrestrial drilling applications as well as full face tunneling or rock breaking machines. As part of an overall research on use of microwave in rock breaking systems, the influence of microwave energy on the mechanical properties of common hard rock types as basalt has been investigated. The results revealed that microwave energy irradiation imposes micro and macro cracks to the surface of the rock being irradiated. In explosive free tunneling applications using TBM, jointed and cracked surface of rock eases the cutting process and increases penetration rate. The experimental setups have been simulated with the help of a multi-physics numerical modeling and the results have been compared with practical experiment. The wave propagation of microwave has been simulated and the distances where the power intensity is higher are identified. Experimental and simulation results underlined the potential impact of the use of microwave energy in underground or surface excavation applications such as mining and tunneling. This will also contribute economically when mine-to-mill operation is fully considered to improve the efficiency of rock crusher stages. INTRODUCTIONDuring hard rock breakage (i.e., separation of a piece of a rock from its parent deposit) in mining and civil applications, the performance of mechanical equipment such as tunnel boring machines (TBMs) is limited by high levels of bit wear and maintenance. Preweakening natural rock prior to breaking it by machine is one approach to lower bit wear and maintenance costs. Some preweakening methods apply heat directly or indirectly. For example, flame torch-assisted TBMs (Lauriello et al., 1974; Resource Technology, 1984) have been deemed economical in terms of equipment, but their feasibility is limited by high fuel consumption. Microwave energy could offer several advantages over the flame torch method: it does not produce emissions or increase fuel consumption (electricity source is available on the machine), and is easy to control (quick power on and off)."

Jan 1, 2015

By O. Mejia

"As study was undertaken to investigate the relationship between mill liner wear and grinding energy efficiency and to assess the opportunity to control mill speed to improve energy performance as mill liner wears. The study involved analysis of plant operating data and liner wear profiles over time. The operating work index was found to be an effective tool to identify the decrease of grinding efficiency along the liner service. The plant data show that the mill grinding efficiency as determined by monitoring the operating work index, and throughput decreases as liner wears. However, efficiency and throughput can be maintained by either changing the liner more frequently or by increasing the mill speed. Two scenarios for increasing mill throughput were analyzed. The first one involves changing the liner before the efficiency drops and the second one requires increasing the mill speed from 75% to 79%. Both scenarios show financial benefits that can be used in mill operations.INTRODUCTION The analysis of the mill power draw is used in this study as a key parameter for comparing mill liner profile and its effect on mill performance. Current technology and simulation software used in the mining industry do not factor in the impact of liner wear profiles in grinding efficiency and mill throughput (Toor, 2013). To address this gap, this study provides an analysis of key factors affecting mill throughput and grinding efficiency: mill speed, ball loading, and liner profiles. Several years of plant mill operating data, published research papers, and MillTraj® simulation results are used to demonstrate that face angles impact grinding efficiency and throughput and that mill speed can be used to overcome this problem. Moreover, the liner profile wear analyses clarify a mismatch between actual and estimated power draw calculations."

Jan 1, 2019

By Chantale Doucet

L?utilisation du remblai en pâte dans les exploitations en vrac est de plus en plus importante. Puisque la technologie existe pour fabriquer du remblai en pâte sans construire une usine coûteuse, il est maintenant possible d?élargir le domaine d?utilisation du remblai en pâte pour y inclure des gisements filoniens où le besoin annuel de remblai est moindre. Dans certains cas, l?utilisation du remblai en pâte pourrait permettre de réaliser d?importantes économies telles que la réduction de la dilution, la stabilité des ouvertures, la récupération d?une plus grande partie du minerai par la réduction de la taille des piliers et l?entreposage de moins de résidus à la surface. L?ampleur des économies est parfois difficile à chiffrer mais il est tout de même important d?en tenir compte lors de la décision d?utiliser du remblai en pâte puisque ce sont souvent ces économies qui seront déterminantes. Différentes méthodes d?extraction avec remblai en pâte appliquées aux mines filoniennes seront présentées. Des défis et les solutions reliés à l?utilisation du remblai en pâte à la Mine Doyon seront discutés.

Oct 1, 2001

By J. Ouellet

The design of hydrostatic liner for a deep potash mine shaft in Saskatchewan poses tremendous technological challenges. Technology has evolved to a point where one could consider a new innovative approach to hydrostatic liner design. But there is still a place for conventional technologies such as cast iron tubbings. As will be discussed in this paper, improvement to manufacturing process, installation procedures and even new materials can bring this technology to an excellent level of performance. With the spur of new projects in the potash industry of Saskatchewan, the authors worked in various shaft liner designs from the conceptual stage through to the construction phase. They were either directly leading the design work on some of these projects or acting as an external reviewer on others. Most of these shaft liner designs involved cast iron tubbing technology and ground freezing. The major challenge in sinking potash shafts in Saskatchewan is to go through a water-bearing ground formation under high pressure, known as the Blairmore or Manville fm. The only proven stabilizing technology for these formations is ground freezing. For a potash shaft, dry shaft conditions are highly desired, so a fully waterproof hydrostatic liner is required. All the existing potash mine shafts in Saskatchewan, except for two with composite steelconcrete lining, used the cast iron tubbing technology. Two new shaft tubbing liners have been constructed recently, one in the Athabasca Basin and one for a potash mine in Saskatchewan. When the authors began working on these new projects, what became quickly evident is that the technological knowhow for designing and constructing tubbing liners was no longer available within Canada and that the past construction methods used to sink tubbing lined shafts was obsolete. The tubbing liner for the shafts sunk in the sixties were designed either by German or British companies. In both of these countries only few tubbing lined shafts were sunk in last 40 years and the technology used in the sixties was not improved. There are only few countries where tubbing is routinely produced and installed: China, Russia, Ukraine and Poland. Out of these countries Poland is the one where this technology is the most advanced. The authors, working in close collaboration with engineers from Poland, attempted to rebuild this knowledge for the mining industry in Canada. This process involved thorough analysis of old technical reports, literature review and study of current polish design and construction practices as well as site visits of existing shafts. Through actual construction experience, some lessons were learned as well as ideas for improvements. In this paper, the authors will present a succinct review of design and procurement process. But, the practical aspects of the construction and installation methodology will be treated with more emphasis, more specifically the practice leading to good liner performance. Some of the poorly understood technical aspects of tubbing installation will be discussed more thoroughly and some currently accepted myths dispelled.

Aug 1, 2013

By Frederik H. Kriel, John Ralston, Craig Priest

"Stream-based microfluidic solvent extraction offers a novel alternative to bulk-scale mixer-settler operations. However present maximum throughputs are restrictive and there are engineering challenges that need to be overcome before the technology is robust. This is especially the case for mineral processing, where circuits must be able to handle variable feed streams with long retention times and where maintenance should be minimized. This paper highlights research directed at investigating and evaluating these challenges for actual mineral leach solutions of metal ions. Molecular and particulate channel fouling is discussed. Most extraction systems studied to date show no effects that would preclude use of the technology. For rare earth elements (REE) with fast extraction rates, scale-up of volumetric throughput to 100 L/h using suitable arrays of channels, microfluidic chips and modules is shown to be achievable using a small contactor (approx. 2 m3) platform. This requires only 2–3 % of the typical aqueous phase inventory and residence time used in an equivalent mixer-settler. For a circuit with 100 contactors, the overall residence time would be less than 1 h, using an aqueous inventory of 40 L.INTRODUCTIONHydrometallurgy is of pivotal importance in many mineral processing circuits around the world, with liquid-liquid solvent extraction (SX) a key step in the separation of many base metals (e.g. Cu and Ni), radioisotopes, precious metals, and the ‘technology’ metals, such as rare earth elements (REEs) (Ritcey & Ashbrook, 1979). The standard equipment for SX in mineral processing is the mixer-settler, in which liquid dispersions are created, by agitation, to increase the surface-to-bulk ratio and, thus increase the mass transfer rate between the liquid phases. In stream-based microfluidic SX (microSX), these high surface-to-volume ratios are achieved by contacting microscopic streams (Ciceri, Perera, & Stevens, 2014), rather than forming small droplets, so that phase disengagement can be accelerated (essentially instantaneous via branching of the two streams of liquid at a channel junction). MicroSX is profoundly different from bulk mixer-settler SX operations and offers exciting opportunities for processing hydrometallurgy solutions (Kriel, Holzner, Grant, Ash, Woollam, Ralston, & Priest, 2015; Priest, Zhou, Klink, Sedev, & Ralston, 2012). Nonetheless, the advantages of using microfluidic environments are presently balanced by very significant challenges relating to throughput, process control, coupling of stages, flow stability, and fouling. If these challenges can be met using smart chip designs, process control and clever engineering, high-value/low-volume SX processes stand to benefit greatly."

Jan 1, 2016

By R. T. Saxon

Prior to November 1975 there were several failures of front -wheel spindles on large haulage truck s in B.C., attributed to fatigue cracks. Since that time, a non-destructive test program has succeeded in detecting the cracks before catastrophic failure, However, the author regards the failures as just one example of a. general unreliability in large high-strength steel castings and urges the industry to look to forgings for sensitive components of heavy equipment.

Jan 1, 1977

By J. S. DeLury

The last few years have been eventful ones for Manitoba in connection with mineral development. Perhaps the past year has been the most important of all. It is therefore a suitable time to review the mining situation in the Province. In order to obtain, in the following paper, a proper set ting from which to discuss the trend of recent developments, a brief review of the story of mining will first be given. This will include a summary of a few of the outstanding facts regarding prospecting, discovery, and operations in the several known metalliferous areas of the Province. Following this will come a more detailed description of activities during the past year or two. Special attention will then be paid to the outstanding enterprises, such a~ those associated with the names of Flin Flon, Sherritt-Gordon, and Central Manitoba, names which have been attracting the attention of the mining world to Manitoba. And last of all will be presented a brief summary of mineral production, which, so far, has largely been credited to non-metallics. HISTORICAL To aid a proper comprehension of the recent trend in mining, it is well not to lose sight of the history of development in the different metalliferous areas in Manitoba. This Province seems throughout to have been more or less dependent on mining interest excited by discoveries in the neighbouring province of Ontario. The first interest came as an effect of the Lake of the Woods mining boom, when small adjacent parts of Manitoba were prospected. Several discoveries were made, but no mining industry resulted.

Jan 1, 1929

By A. MacKinnon, P. W. Kingston, W. F. Caley

"Wollastonite (CaSiO3]) is experiencing increased usage in a variety of applications, such as fillers in paints, plastics and resins, as an extender to replace both non-fibrous and fibrous materials (e.g. asbestos), and in the glass and ceramics industries. Significant new deposits of wollastonite have been discovered in Marmora Township, about 175 km northeast of Toronto. The geological setting of these large-tonnage. High grade deposits has recently been investigated to assess the possibility of their development. A preliminary study of the chemistry, as well as the mineralogy of six occurrences is presented. Based upon this information, it is suggested that several of the deposits have an excellent development potential.INTRODUCTIONWollastonite is an anhydrous calcium metasilicate (CaSiO3), with a theoretical composition of 48.3% CaO and 51.7% SiO2; the calcium may be partially replaced by iron, manganese, magnesium, and strontium. Commonly associated minerals include diopside, tremolite, idocrase, grossularite andradite, quartz, and calcite. Wollastonite forms as a contact metamorphic mineral within impure limestone near intrusive bodies of granite, or other acidic rocks, as the result of metasomatism of calcareous sedimentary rocks, or by the crystallization of certain magmas (e.g. carbonautes). Generally, the reaction of calcite with silica to produce wollastonite occurs when siliceous hydrothermal fluids from a granitic intrusion or primary silica in the limestone/marble react with calcite in limestone at temperatures between 450°C and 600°C."

Jan 1, 1989

By M. Samuels

"Block and panel cave mining methods are being increasingly proposed as they allow massive, deeply situated ore-bodies to be mined economically at a time when discovery rates of significant near surface deposits are declining. Cave-to-Mill, a mine-to-mill approach for block cave mines, defines ore block models with respect to both mine and mill performance. A cave-to-mill study for the New Afton block caving operation focused on identifying value opportunities related to fragmentation and sorting for a future lift as development progresses deeper. The lack of selectivity and potential for dilution associated with the block cave mining method results in many caving operations having to mine and either dispose of or process material that is below cut-off grade at certain stages of production. As an outcome of the study, the variation in cave fragmentation size and the sensitivity of mill throughput to feed size was examined. To evaluate the amenability of bulk and particle sorting, Prompt Gamma Neutron Activation Analysis and X-Ray Fluorescence sensors were tested. A conceptual bulk and particle sorting flowsheet is presented. Grade data from regular underground sampling was used to predict the performance of a bulk sorter. A heterogeneity analysis of material reporting to drawpoints helped to identify areas of the extraction level that experience high variations in grade and thereby stand to benefit from dedicated ore and waste material handling systems should underground bulk sorting be implemented.INTRODUCTION Block and panel caving are low-cost underground mass mining methods that are suitable for excavating weak, massive and steeply-dipping orebodies. Accordingly, cave mining methods have predominantly been used to mine copper porphyry and diamond bearing deposits. Due to the increasing depletion of near-surface orebodies, it is expected that block and panel caving methods will be increasingly used in the copper-gold industry. Their implementation holds significant potential to extend the life of existing open-pit operations by providing an economic means to access ore located at depths that are beyond the practical limits of open-pit mining. Examples of cave mines proposed for British Columbia include the Kwanika Mine, Red Chris underground, Kemess Underground project, and the Iron Cap and Mitchell cave mines of the Kerr-Sulphurets and Mitchell (KSM) project (Moose Mountain Technical Services, 2017; Imperial Metals, 2017; Golder Associates, 2017; Tetra Tech, 2016)."

Jan 1, 2018

By B. R. MacKay

Introduction During the past six seasons the writer has been engaged in semi-detailed investigations on the coal areas lying along the front of the Rocky mountains between the Brazeau river and the Smoky River Coal Reserve (see Map, Figure 1). The purpose of this paper is to present some observations pertaining to the stratigraphy and structure of the district, touching especially upon the lithological units into which the Lower Cretaceous sediments have been divided, the thicknesses of the formations at different localities, the number, thicknesses and horizons of the principal coal seams, and the structural conditions which exist in the various fields.

Jan 1, 1930

By Henri-Louis Jacob

Le secteur des substances non-metalliques repose au Quebec sur !'exploitation et la transformation d'une dizaine de mineraux ainsi que sur la production de materiaux de base destines surtout a l'industrie de la construction. L'ensemble de cette production representait en 1982 une valeur estimee a plus de 797 millions $, soit tout pres de 400Jo de la production minerale du Quebec. L'amiante et Jes scories de titane destines a la production de pigments, qui comptent parmi Jes plus importantes substances minerales produites au Quebec, representent respectivement 370Jo et I 70Jo de la valeur totale des non-metalliques tandis que le groupe des materiaux de construction represente pres de 400Jo. Les autres substances, parmi lesquelles ressortent nettement la tourbe, la silice et la magnesite, representent une valeur totale de 61.5 millions $.

Jan 1, 1984

By Edward Thomas

Note. - Securing mine roof through consolidating thin or otherwise incompetent strata to increase overall thickness of the immediate roof beam is a new method of roof support and control which has aroused great interest amongst mining engineers and which is now being experimented with and thoroughly investigated by the United States Bureau of Mines. A paper on Roof Bolting, illustrated by photographs and motion-picture films, will be presented by Edward Thomas, of the U. S. Bureau of Mines, at the forthcoming Annual Meeting of the Mining Society of Nova Scotia. In the following pages, Mr. Thomas describes the methods used in roof bolting as illustrated by the photographs that accompanied his paper. The photographs are supplied through the courtesy of the United States Bureau of Mines, whose willing cooperation with miners and mining engineers in Canada is very well known and even more greatly appreciated. This method of publishing Mr. Thomas's paper is adopted because few, if any, Canadian mining engineers have actually seen installations of roof bolts and it is felt that the best possible presentation of such an interesting subject through the medium of the Bulletin will be attained by publication of the photograps over explanatory captions. - Ed.

Jan 1, 1950

"Liberation is a key requirement for efficient separation in mineral processing. As a consequence of this an understanding of the inherent textural features of an ore is no longer possible since during the process of liberation, texture is destroyed. Knowledge of key textural features, such as mineral grain size and distribution, prior to breakage processes provides the opportunity to understand the textural drivers for ore hardness. Modern characterisation methods, including automated SEM-based techniques, provide the possibility of measuring mineral characteristics at a range of scales. This paper discusses how textural features of two different ore types in a porphyry copper deposit can be measured and interpreted at a number of scales. Standard breakage tests conducted on the ores indicate that one of the ores can be characterised as hard and the other as soft. The impact of mineral grain size and the presence and scale of vein type structures in the two ores have been used to determine the extent to which these features influence ore hardness.INTRODUCTIONIn order to effectively convert ore into metal, knowledge of both the processing stages and the characteristics of the ore are essential. Prior to the advent of technologies that enabled the fundamental understanding of the sub-process at each stage of processing and the measurement of appropriate ore properties the most effective way to understand how an ore would respond to a process was to put it through that process, for example the way to determine how an ore would break was to first break it. Existing comminution models seek to predict the size distribution of rock fragments as the result of applied energy based on knowledge of the rock strength. It is common for these models to consider the rock as homogeneous and despite providing important data for the design and optimisation of industrial comminution circuits these models are only applicable within a narrow range of operation. In order for reliable predictive models to be developed that account for the inherent ore characteristics, a step change is required in the type of measurements that are carried out to characterise an ore and the type of data that is extracted and used as model inputs."

Jan 1, 2016

By C. R. Stelck

"AbstractThe Cardium formation of northeastern British •Columbia •contains an erosional unconformity that becomes progressively more severe northward until, •at Liard river, the stratigraphic hiatus eliminates the underlying Lower •Cardium sandstone, the Kaskapau formation, and the upper Dunvegan sandstones. The area of unconformity roughly coincides with the distribution of the continental facies of the earlier Dunvegan formation. Along Wapiti river, the zone fossil Scaphites ventricosus Meek and Hayden is found in the Bad-heart member of the overlying Wapiabi shale; Scaphites :preventricosus. Cobban marks the base of the Wapiabi shale; Scaphites cf. corvensis •Cobban is found in the middle shale member of the •Cardium formation. The log of the Red-Willow No. 1 well shows close similarity to the outcrop sections south of Wapiti river. The Cardium formation is mainly late Turonian in age. Two other pre-Cardium Turonian sands of north-eastern British Columbia are named the Wartenbe and Tuskoola sands.IntroductionTHE Upper Cretaceous Cardium (Bighorn) sandstone formation of the Foothills of northeastern British Columbia carries within its formational limits an erosional unconformity. The unconformity decreases to the southeast, becoming in immediate shoreline regions, now under the plains, a minor diastem. Such diastems, or stratigraphic intervals of non-deposition, occurring in the shallow unda-zone are paralleled in the deeper portions of the unda-zone by the phenomena of sub-aqueous winnowing. '.This winnowing and re-working •at critical depths creates sand areas with porosity."

Jan 1, 1955

By J. E. Danoczi

ABSTRACT A diamond processing plant is being designed for the Star–Orion South diamond project in central Saskatchewan. Key to the plant is diamond liberation, which occurs in the comminution section and is the process of breaking up kimberlite rock as gently as possible to minimize diamond damage, particularly in larger, high-value diamonds. Kimberlite from the crater area of a volcanic pipe is generally softer than kimberlite from the diatreme zone. Softer kimberlite, comprising the majority of Star– Orion South deposits, can be readily broken up using abrasion and attrition by autogenous grinding mills, the preferred comminution method for minimizing diamond damage.

Jan 1, 2013

By V. Vakiloroaya

The paper aims at developing a hybrid solar-assisted air conditioner system for performance enhancement and energy efficiency improvement. To increase sub-cooling of the refrigerant at partial loads, we propose a new discharge bypass line together with an inline solenoid valve, installed after the compressor to regulate the mass flow rate of the refrigerant vapour passing through a hot water storage tank. For control design, a lumped parameter model is first developed to describe the dynamics of the system in an explicit form of input-output relationship. The system has been fully-instrumented to examine its performance under different operation conditions. The system model is then validated by extensive experimental tests. The predictions from the models exhibit a good coincidence with experimental results, judging by an RMS error less than 15%. Based on the obtained dynamic model, a linear quadratic regulator (LQR) is applied to optimize a cost function of the output errors and control efforts. The key challenge is to regulate the refrigerant temperature entering the condenser by controlling the valve opening. The design approach is then tested in a transient simulation tool to predict the system performance in transient conditions. The experimental results obtained from implementation with PLC demonstrate that the proposed system delivers higher system efficiency owing to the higher refrigeration effect in the direct expansion evaporator. Thus, the novel development is promising for improvement of energy efficiency, enhancement of the system performance while fulfilling the cooling demand. Consequently, between 25 and 43% of monthly electricity can be saved on average.

Aug 1, 2013

By A. M. Hadian

The use of dolomite refractories in steel making and cement industries has advantages over other basic products particularly in countries where this type of refractories is produced. Due to existence of high-quality dolomite deposits in many regions of Iran, there is a good potential for producing dolomite refractories in the country. This study focuses on the effect of such additives as iron oxide and alumina on hydration resistance and density of Iranian dolomite. It was found that addition of Fe2O3 is more effective than Al2O3 on increasing density as well as resistance to hydration of dolomite.

Jan 1, 2004

By G. V. Theja, V. B. Maji

Large infrastructure projects like tunnel excavations, underground constructions face innumerable risks. For successful completion of these projects, it is essential that we foresee and understand risks that could occur during different phases of the project. One of the risks affecting underground excavation projects is the inaccurate performance prediction of TBMs. As this could severely affect the project, resulting in lower advance rates and could also result in changing the excavation machine or method, due to difficulties in excavation, thereby increasing the overall cost of tunnelling. This makes performance prediction of the TBMs as one of the crucial aspects in tunnelling, as a precise estimation of its performance is required for planning and estimation of time and cost of the tunnelling projects. This performance prediction of TBM is a challenging geotechnical problem that is intricate and complex in nature, this is possibly due to the fact that TBM performance prediction involves understanding the rock fragmentation process in wide range from micro-scale (i.e. the interaction of surface of rock material and cutter tip) to macro-scale (including the interaction of rock mass and TBM). Thus in order for the performance prediction model to be efficient, parameters of both TBM specifications and ground conditions have to be considered. Various models have been proposed by researchers since the early phases of TBM application, these studies resulted in the development and improvement of numerous penetration prediction models. Most of these models consider the geotechnical parameters that are input to the model to be consistent along the TBM drive and neglect the uncertainties in parameters that occur. And so to improve the predictive capability of these models and to incorporate the above uncertainties, the penetration rate is modeled as a stochastic variable depending on the geotechnical and TBM parameters, its statistical distribution is determined and is used to characterize the penetration rate instead.

Jan 1, 2015