This thesis is based on a case study of the Kiirunavaara sublevel cave (SLC) mine. It focuses on footwall stability and damage development in the mining infrastructure on mine scale. Damage to the infrastructure is mappable for the full height of the footwall by access through decommissioned infrastructure associated with earlier mining stages. Damages range from pure structurally controlled failures (wedge failures) in the upper part of the footwall to fracture growth through intact rock combined with micro‑seismic emissions at the active mining depth. The thesis addresses four distinct research questions; (i) What are the predominant failure mechanisms for the Kiirunavaara footwall? (ii) What is the role of confinement on the damage development in the footwall? (iii) How does the SLC relate to the footwall damage development? (iv) How can infrastructure damage associated to the future mining be estimated using currently available data? Two sets of calibrated numerical models were used to study the damage evolution processes using damage mapping data as the main calibration parameter. Validation of the models was achieved by correlation of model output to micro-seismic locations. The modelling and damage mapping results were used as the basis for the development of a simple prognosis tool for estimating the ultimate extent of infrastructure damage associated to the mining advance for future mining steps. A literature review on slope failure modes, large scale failures in cave mining and failure tracking using micro-seismic locations is included to provide background and definitions. The literature describes principal failure modes as well as mechanism combinations such as structurally controlled failures initiated by deep seated rock mass failures or relaxation. Cases are presented where previously stable structures become destabilised by cave advance and examples where micro‑seismic recordings were used to track deformations and the initiation and growth of newly formed fractures. The Kiirunavaara SLC mine is presented in detail as the main case study of the work. The mine has been in operation since the early 20th century with a transition to underground operation over 50 years ago. The extent of the orebody is 4 km in length with an average width of 80-90 m, the termination at depth has yet to be determined. The ore has an average dip of 60˚ east and a dip-along-strike to the north. Both the footwall and hangingwall rock masses are considered hard and competent with UCS values for the footwall ranging from ca. 130 MPa to extreme cases of 600 MPa. The ore is mined in production blocks about 400 m wide (along strike), Mining of the northernmost blocks, situated in the Lake ore, did not start as open pit operations but has been accessed from the underground via SLC only. The instabilities in the footwall has been addressed by several research studies in the past, with the predominant failure mechanisms in different studies being suggested as large scale tensile failure, complex wedge failure, or rotational shear failure, i.e., some type of principal slope failure. In this work, conceptual numerical models in UDEC were calibrated to fit underground damage mapping data by tracking numerical shear strain concentrations. The conceptual models suggested rock mass damage without the indications of development of large scale slope failure mechanisms such as shear bands. Mine scale PFC models were calibrated with respect to the rock mass strength parameters derived by the conceptual UDEC models and used to study rock mass fracturing in the absence of large scale failure. It is shown that damage to the rock mass occurs mainly close to the active mining in a seismically active zone. This is suggested to weaken and soften the rock mass to allow the development of infrastructure damage in this volume to occur as the rock mass relaxes when entering the stress shadow of the SLC as mining progresses. The damage to the rock mass at the production depth is argued, based on seismic records and a parametric study in UDEC, to constitute of large quantities of local shear failures coalescing to appear as a large scale step-path or rotational shear failure in mapping records. The extent of the associated infrastructure damage is predicated to be limited by the extent of the damaged rock mass zone. A simple bi-linear equation is suggested using ore-width and mining depth as input to estimate the ultimate extent of the damaged zone for each mining stage and thus the limit of later infrastructure damage development. The thesis is concluded with recommendations for future work and potential for continued research. / Denna avhandling baseras på en fallstudie av skivrasgruvan Kiirunavaara. Fokus ligger på liggväggstabilitet och skadeutveckling på gruvans infrastruktur i gruvskala. Infrastrukturskador kan karteras längs med hela liggväggens höjd där tillgång till bergmassan ges via urdrifttagna ortar och ramper drivna i samband med tidigare brytningssteg. Dokumenterade skador varierar med djupet – från strukturstyrda brott i den övre delen av liggväggen till ny sprickbildning genom intakt berg kombinerat med mikro-seismik vid nuvarande brytningsdjup. Fyra distinkta forskningsfrågor avhandlas; (i) Vilka är de dominerande brottsmekanismerna i Kiirunavaaras liggvägg? (ii) Vilken roll spelar inspänning för brottsutvecklingen i liggväggen? (iii) På vilket sätt relateras skivrasbrytningen till brottsutvecklingen? (iv) Hur kan skador på gruvans infrastruktur kopplat till framtida brytningssteg uppskattas med data tillgängliga idag? Två omgångar med kalibrerade numeriska modeller togs fram för att studera skadeutvecklingen i liggväggen med skadekarteringsdata som primär kalibreringsparameter. Validering av modellerna uppnåddes genom att studera samstämmigheten mellan modellresultaten och lokaliseringen av mikro-seismiska händelser. Modellresultaten och skadekarteringsdatabasen användes som grund för att utveckla ett enkelt prognosverktyg för att uppskatta den slutgiltiga utbredningen av infrastrukturskador direkt associerade med gruvbrytningen för framtida brytningssteg. En litteraturstudie av släntbrott, storkskaliga brott i samband med rasbrytning samt brottsövervakning med mikro-seismik är inkluderad som bakgrund och för att definiera terminologier som används genom avhandlingen. Literaturstudien beskriver principiella brottsmekanismer samt kombinationer av mekanismer såsom strukturstyrda brott pådrivna av djupt belägna bergmassebrott eller minskad inspänning. Fallstudier presenteras där tidigare stabila strukturer destabiliseras av rasbrytningens framskridande och exempel där mikro-seismikdata använts för att följa deformationer samt initiering och tillväxt av nya sprickor i intakt berg och bergmassa. Kiirunavaaragruvan presenteras i detalj som den huvudsakliga fallstudien för arbetet. Gruvan har varit aktiv sedan tidigt 1900-tal med övergång till underjordsbrytning för över 50 år sedan. Malmkroppens utbredning är 4 km längs strykningen med en genomsnittlig vidd av 80-90 m, och malmkroppens fortsättning mot djupet är öppen. Malmen har en genomsnittlig stupning av 60 grader öst med en fältstupning mot norr. Bergmassan i både liggvägg och hängvägg anses vara hård och kompetent med UCS värden för liggväggen mellan ca. 130 MPa till extrema fall av 600 MPa. Malmen bryts i produktionsblock med ca 400 m bredd (längs malmens strykning). Brytning av de nordligaste blocken, belägna i Sjömalmen, har inte skett i dagbrott utan har utförts enbart via skivrasbrytning. Instabiliteten i liggväggen har avhandlats i ett flertal tidigare studier. De dominerande brottsmekanismerna har föreslagits i tidigare arbeten som storskaligt dragbrott, komplext kilbrott eller cirkulärt skjuvbrott d.v.s. någon typ av principiellt släntbrott. I arbetet för denna avhandling kalibrerades konceptuella numeriska modeller i UDEC mot skadekarteringsdata från liggvägens underjord, med avseende på koncentrationer av skjuvtöjningar. De konceptuella modellerna visade på bergmasseskador utan indikationer på storskaligt släntbrott, exempelvis koncentrationer av numeriska skjuvband. PFC-modeller i gruvskala kalibrerades gentemot bergmasseparametrarna från de konceptuella studierna i UDEC för att direkt studera upprickningen av bergmassan i frånvaro av storskaliga brottsindikationer. Modellerna visade på att skador i bergmassan främst uppkommer nära brytningsområdet i en seismiskt aktiv zon. Detta föreslås försvaga och mjukgöra bergmassan vilket i sin tur leder till utveklingen av infrastrukturskador i den skadade volymen när berget avlastas då området hamnar i spänningsskugga från skivraset. Ovanstående studier visar att skadorna som uppkommer i bergmassan, baserat på de konceptuella UDEC-modellerna och mikro-seismiska data, består av ett stort antal lokala skjuvbrott vilka samverkar till att framstå som ett storskaligt trappstegsbrott eller cirkulärt skjuvbrott i skadekarteringsdatat. Utbredningen av de relaterade infrastrukturskadorna förutspås begränsas av utbredningen av bergmasseskadorna uppkomna vid bryningen. Ett enkelt bi-linjär samband föreslås vilket använder malmbredd och brytningsdjup för att uppskatta den slutgiltiga utbredningen av skadezonen i bergmassan för varje brytningssteg, och i förlängningen begräsningen av senare uppkommande infrastrukturskador. Avhandlingen avslutas med rekommendationer för fortsatt arbete samt framtida forskningspotential.

In coming decades, many underground mines will operate at greater depths, which will affect many operational factors such as increased rock stress, longer haulage distances, and higher energy consumption, which potentially can generate lower production rates. The increased rock stresses may lead to smaller sized openings, further restricting the size of loading and hauling equipment that can be used. Longer hauling distances result in increased energy consumption for loading and hauling equipment, and in turn, high energy consumption increases heat and gas emissions for diesel equipment. Heat emission increases ventilation costs as large volumes of air must be circulated to cool diesel engines and simultaneously maintain adequate air quality for personnel.The research presented in this thesis was carried out to evaluate and analyze different haulage systems, including diesel and electric trucks, shafts, and belt conveyors. The aim was to determine how these various material-handling equipment may produce the desired production objectives and lead to lower energy costs. The net present value (NPV) of the mine plan at increasing mining rates and altered commodity prices was also analyzed. The method used was the combination of discrete event simulation and mixed integer programing. Discrete event simulation was used to estimate mine production for different haulage systems, and the results were used to compute appropriate mining costs for each hauling option. Mixed integer programming (MIP) was then used to generate the optimal production schedule and mine plan. The analysis showed that an increasing use of electric trucks will have positive effects on production improvement because electric trucks have shorter cycle times than their diesel counterparts. Therefore, electric trucks can make more cycles than diesel trucks in the same period of time. The analysis also showed that low-profile equipment will remain viable for haulage in high stress environments that result in smaller sized mine openings. In addition, when friction hoist systems are used, rope speed and skip payload play important roles in production improvement. With belt conveyors, production improvements can be obtained by increasing surcharge angle and running the belt at a low speed. For long hauls, the troughing angle should be increased and the belt operated at a higher speed.Energy costs increase with depth and are higher for diesel trucks compared with other haulage options. At 1000-meter depths and with current energy prices, energy costs for diesel trucks, electric trucks, belt conveyor, and shaft account for 62%, 54%, 25%, and 14% of the total haulage costs, respectively. These findings indicate that minimizing the usage of diesel engine machines will have greater benefits towards cost reductions in an era of increasing energy prices and greater mine depths. Diesel machines also have high heat and gas emissions, which increases operating costs particularly for deeper mines where heat emissions increase ventilation costs.Changes in mine plans based on changing commodity prices at a fixed mining rate resulted in an increase in the NPV from $96M to ultimately $755M for the studied case. An increase in mining rate from 300,000 to 450,000 tonnes raised the NPV to $773.45M. This finding indicates that even though an increase in mining rates increases costs, companies may find that pursuing such a course is beneficial at certain commodity prices, especially when the price is elevated. When the price falls, increasing mining rate may need a detail evaluation of other parameters such as grade, recovery, and investment changes.The evaluation showed that the method of combining discrete event simulation and mixed integer programming can yield a feasible solution and better understanding of the operational systems and reduce risks in selecting a system before it is implemented. This study provides mining companies an analysis of the use of underground haulage systems that can aid decision making. / Godkänd; 2014; 20141021 (abusal); Nedanstående person kommer att disputera för avläggande av teknologie doktorsexamen. Namn: Abubakary Salama Ämne: Gruv- och Berganläggningsteknik/Mining and Rock engineering Uppsats: Haulage System Optimization for Underground Mines Opponent: Professor Jazek Paraszczak, Université Laval, Canada Ordförande: Professor Håkan Schunnesson, Institutionen för samhällsbyggnad och naturresurser, Luleå tekniska universitet Tid: Torsdag den 27 november 2014 kl 10.00 Plats: F1031, Luleå tekniska universitet

Degradation is an on-going process in systems, equipments and components subjected to various stresses and adverse operating conditions. The factors influencing the degradation process may adversely affect the system or component performance. A study of these factors will provide a basis for making correct decisions concerning corrective and preventive measures. Such a study is also useful for reliability analysis of the degrading systems/components for making maintenance decisions or for initiating measures for changes in the design. Many times it is not possible to implement design changes due to complexities and cost considerations, as in the case of railway infrastructures, etc. In such situations operational reliability is assured through effective maintenance actions. Knowledge of the technical condition of components is important to achieve the optimal maintenance policy in order to minimize the total system risk. A methodology for rail defect prioritization and risk assessment is developed to support the decision- making process during the effective scheduling of the inspection frequency based on the type of defect and its risk of developing into a rail break. The present research work also demonstrates an application of reliability analysis to improve system reliability based on design changes. This has been illustrated with an example from a manufacturing industry. The objective is achieved using cost-benefit analysis in combination with failure data and root cause analysis. The analysis of failure data with the different cost elements involved in the operation and maintenance of the complex systems is presented as a basis for choosing between alternative designs. Furthermore, an optimization model has been developed to estimate the optimum inspection frequency required at the minimum maintenance cost based on the technical condition of the component. The model has been validated by a case study of an offshore oil and gas platform. The consequences of not choosing the right distribution have also been discussed in the thesis. The concept of the virtual failure state has been introduced to estimate the failure distribution of highly critical components. The factors influencing the degradation process have been identified and studied in detail. A framework for classification of rail failure data has also been developed for rail life estimation using reliability analysis. In short, the thesis discusses the application of reliability analysis and cost modeling techniques to support the decision-making process in operation and maintenance activities and demonstrates its usefulness in real life. / Godkänd; 2008; 20080328 (ysko)

All businesses need equipment to deliver services or manufacture goods. Over time, this equipment will degrade, but with proper maintenance, the degradation can be controlled, and failed equipment can be restored to operational status. Run-to-failure maintenance is performed when equipment or systems break down. In preventive maintenance, equipment is maintained as a precautionary measure to prevent failure. Finally, condition-based maintenance recommends maintenance actions based on the condition of the asset.The railway is a superior mode of transport if capacity, speed and environment are the main criteria; it also plays a crucial role in heavily crowded regions. The condition of the wheels and the rails affects rail- way safety, and infrastructure regulators and managers are always trying to reduce potential risk areas. The wheel-rail interface triggers most of the cost for maintenance.The railway wagons in this research use a time-based maintenance strategy, a strategy which does not fully consider the actual health of the asset. However, by using condition data from observations, along with diagnostics and prognostics, an effective condition-based maintenance strategy can be planned effectively way and executed efficiently.The results of this research suggest the efficacy of using automatic condition monitoring systems to increase the amount of available data for analysis and maintenance support planning, rather than depending on a system where operators or maintenance personnel do the measurements. The results also indicate that continuous monitoring of lateral forces will decrease the risk of derailment.Condition monitoring data can support maintenance preparation, assessment, and improvements and help to form a continuous improvement loop. This, plus a condition-based maintenance strategy, will lead to capacity assurance. / Godkänd; 2014; 20131125 (mikpal); Tillkännagivande disputation 2014-01-07 Nedanstående person kommer att disputera för avläggande av teknologie doktorsexamen. Namn: Mikael Palo Ämne: Drift och underhållsteknik/Operation and Maintenance Avhandling: Condition-Based Maintenance for Effective and Efficient Rolling Stock Capacity Assurance A Study on Heavy Haul Transport in Sweden Opponent: Professor Doug Hargreaves, Science and Engineering Faculty, Queensland University of Technology, Australia Ordförande: Professor Uday Kumar, Institutionen för samhällsbyggnad och naturresurser, Luleå tekniska universitet Tid: Måndag den 3 februari 2014, kl 10.00 Plats: C305, Luleå tekniska universitet

Impact-loaded conical and cylindrical friction joints are studied theoretically and experimentally. The system considered consists of a long, straight, cylindrical and linearly elastic rod which is impacted axially at one end, and which has a body attached by means of a friction joint at the opposite end. The conditions are such that the wave propagation is 1-D in the rod and can be neglected in the attached body. Slip and energy dissipation due to an impact load are determined. The theoretical results of the impact-loaded conical friction joints exhibit phenomena which sometimes have spectacular appearance. The agreement between theoretical and experimental results is fair. The influence of blow frequency and thrust on the performance of a percussive rock drill is studied theoretically. The drill considered consists of hammer, adapter, rod and bit. Two different rock drills are studied. The first is a simple drill with constant characteristic impedance throughout the drill. The second is a prototype of a high frequency percussive rock drill. The efficiency and the maximum (maximum tensile) and minimum (maximum compressive) stresses are determined. For the simple drill the average efficiency in the range from soft to hard rock is only weakly dependent on the blow frequency up to relatively high blow frequencies but strongly dependent for extremely high blow frequencies. It is also found that the maximum and minimum stresses in the drill in the range from soft to hard rock are only weakly dependent on the blow frequency up to high frequencies but strongly dependent for extremely high frequencies. The maximum stress increases and the minimum stress decreases with thrust. / Godkänd; 1986; 20070108 (mlk)

With increasing awareness that maintenance not only ensures safety and track performance, but also creates additional value in the business process; many infrastructure managers and owners are treating maintenance as an integral part of the business process. This is also true for the Banverket (Swedish National Rail Administration). One key issue for Banverket is to verify that the undertaken maintenance activities provides expected results, measured through maintenance performance indicators (MPI) related to technical, economical, and organizational issues. It is also necessary to classify the degree of effect for every single MPI, i.e. to create a logical cause-and-effect structure. The main purpose of this research work is to identify and study the existing operation and maintenance performance indicators related to railway infrastructure, their application in short term and long-term perspective to analyse their usefulness for operation and maintenance planning of the railway infrastructure. Furthermore, the study is to find a structured, reliable, and cost effective method using maintenance performance indicators (MPI) such as OEE-values to facilitate the operation and maintenance decision making process both in short term and long term perspective for the railway infrastructure management. A study at Banverket shows that 10 MPIs out of 17 identified ones are in use, where eight of them match the MPIs identified through the documents and two additional ones identified through interviews. Two conducted case studies at Banverket and Jernbaneverket, the Norwegian rail administration, shows that it is possible to quantify and benchmark MPIs between different countries. The comparison from the Iron Ore Line between Kiruna and Narvik indicated more or less the same rail and track related maintenance costs per track kilometre in Norway as in Sweden. The overhead cost per track kilometre results in 12 times higher costs for Jernbaneverket due to different track length in Norway and Sweden, though the number of employees in the infrastructure manager organization work force was the same in both countries. A case study evaluating technical and financial aspects of grinding campaigns on the track section between Kiruna and Riksgränsen shows that the grinding campaign postpone major rail replacements activities into the future. The yearly cost for grinding and renewal is an example of an aggregated MPI that can be used for future follow-ups and benchmarking. The grinding campaign itself seems not to affect the total system in a negative way. One important issue for the infrastructure manager is to focus on the overall railway infrastructure effectiveness. A model for calculating the overall railway infrastructure effectiveness (ORIE) is presented in this thesis. Performed case studies on three track sections shows similar ORIE figures that are significantly higher than the industry OEE, which is required for a punctual railway transportation system. The study indicates that ORIE must be calculated on a monthly basis. The findings of the ORIE and calculation are 89.7 - 100% ORIE values. The findings indicate that ORIE can be used as a key performance indicator by the railway infrastructure manager. It is also visualized that ORIE can provide important input and support in decision making for the infrastructure managers. A railway infrastructure maintenance link and effect model (LinkEM), that supports the overall objectives and focuses on critical strategic areas determined by the nature of the railway industry and public requirements and regulations is suggested. To conclude, in this research study relevant MPIs for effective management of operation and maintenance of the railway infrastructure are identified and analyzed. Further, models like LinkEM and ORIE are suggested for the railway infrastructure managers to facilitate in the decision-making. / Infrastrukturförvaltare av järnväg ser idag underhåll som en värdeskapande och integrerad del av hela förvaltningsverksamheten för att uppfylla kundernas krav och förväntningar. En central uppgift för Banverket är att verifiera att genomförda underhållsåtgärder ger önskat resultat ur tekniska, ekonomiska och organisatoriska perspektiv. Ett sätt att mäta detta är att använda underhållsrelaterade indikatorer (MPIs, maintenance performance indicators). Det är därför viktigt att dessa indikatorer förmår koppla och visa effekter av genomförda underhållsaktiviteter, dvs. förmår visa underhållsrelaterade orsak-verkansamband.En studie genomförd på Banverket visar att utav 17 identifierade MPIs så används 10 stycken. Åtta av dessa är identifierade i Banverkets egna dokument medan de två övriga är identifierade genom intervjuer. Två genomförda studier på Banverket och Jernbaneverket visar att det är möjligt att kvantifiera och jämföra MPIs mellan olika länder med hjälp utav benchmarking. Jämförelsen visar att underhållskostnaderna per spårmeter är ungefärligen lika stora på svensk och norsk sida för Malmbanan. En liknande jämförelse av overheadkostnaderna visar att kostnaderna på den norska sidan är ungefär 12 gånger högre per spårmeter räknat. En jämförelse av organisationernas storlek till antalet anställda visar dock att de är ungefärligen jämstora. En teknisk och ekonomisk utvärdering av genomförda rälsslipningskampanjer på sträckan mellan Kiruna och Riksgränsen visar att rälsslipning kan fördröja behovet av utbyte av räl. Den årliga kostnaden för rälsbyte är ett exempel på MPIs som kan användas för uppföljning och benchmarking. Genomförda rälsslipningskampanjer ser inte ut att påverka järnvägssystemet som helhet på något negativt sätt. En viktig fråga för infrastrukturförvaltare av järnväg är att kunna mäta järnvägssystemets effektivitet. En modell för att kunna mäta just detta presenteras i denna avhandling, dvs en så kallad ORIE-modell (overall railway infrastructure effectiveness eller infrastruktureffektivitet för järnväg) Genomförda studier och simulering på bandelsnivå visar på höga och jämförbara ORIE-värden för de olika bandelarna, vilka för övrigt är påtagligt högre än för motsvarande OEE-värden för exempelvis tillverkande industri. Studien påvisar att ORIE-värdena bör beräknas per månad och att de kan användas som MPIs. Resultaten visar på ORIE-värden mellan 89,7 - 100 %. ORIE-värden kan därmed utgöra ett bra beslutsstöd för järnvägens infrastrukturförvaltare. Ett förslag på en länk- och effektmodell för järnvägsinfrastruktur vilken stödjer övergripande mål för verksamheten och som fokuserar på strategiska områden utifrån järnvägens förutsättningar presenteras i denna avhandling. Sammanfattningsvis så har denna studie identifierat ett antal MPIs som används av infrastrukturförvaltare av järnväg. Koncept och modeller såsom LinkEM, ORIE och benchmarking har applicerats på och genererat resultat användbara för infrastrukturförvaltare av järnväg. / Godkänd; 2008; 20080416 (ysko)

Reliability prediction of the electronic components used in industrial safety systems requires high accuracy and compatibility with the working environment. The traditional reliability prediction methods that draw on standard handbooks such as MIL-HDBK 217F, Telcordia, PRISM etc., are not appropriate to determine the reliability indices of these components. For one thing, technology is constantly advancing; for another, the empirical data do not always match the actual working environment.The newest reliability prediction methodology, the physics-of-failure (PoF), emphasizes the root cause of failure, failure analysis, and failure mechanisms based on the analysis of parameter characteristics. It involves a focused examination of failure point locations, considering the fabrication technology, process, materials and circuit layout obtained from the manufacturer. This methodology is capable of providing recommendations for the increased reliability of components using intuitive analysis.However, there is a limitation: it is sometimes difficult to obtain manufacturer’s details for failure analysis and quality information. Several statistical and probability modeling methods can be performed on the experimental data of these components to measure the time to failure. These experiments can be conducted using the accelerated-testing of dominant stress parameters such as Voltage, Current, Temperature, Radiation etc.In this thesis, the combination of qualitative data from PoF approach and quantitative data from the statistical analysis is used to create a modified physics-of-failure approach. This methodology overcomes the limitations of the standard PoF approach as it involves detailed analysis of stress factors, data modeling and prediction. A decision support system is created to select the best option from failure data models, failure mechanisms, failure criteria and other factors to ensure a growth in reliability.In this study, the critical electronic components used in certain safety systems from different technologies are chosen for reliability prediction: Optocoupler, Constant Fraction Discriminator, BJT Transistor, Voltage Comparator, Voltage Follower and Instrumentation amplifier. The study finds that the modified physics-of-failure methodology provides more accurate reliability indices than the traditional approaches using field data. Stress based degradation models are developed for each of the components. The modified PoF models developed using Response Surface Regression and Support Vector Machine (SVM) show better performance. / Godkänd; 2013; 20130813 (aditha); Tillkännagivande disputation 2013-08-23 Nedanstående person kommer att disputera för avläggande av teknologie doktorsexamen. Namn: Adithya Thaduri Ämne: Drift och underhållsteknik/Operation and Maintenance Avhandling: Physics-of-Failure Based Performance Modeling of Critical Electronic Components Opponent: Professor Hoang Pham, Dept of Industrial and Systems Engineering, Rutgers, The State University of New Jersey, USA Ordförande: Professor Uday Kumar, Institutionen för samhällsbyggnad och naturresurser, Luleå tekniska universitet Tid: Torsdag den 12 september 2013, kl 10.00 Plats: F1031, Luleå tekniska universitet

The railway is an important mode of transport, due to its environmental friendliness, high safety level, and low energy consumption combined with a high transport capacity, among other factors. The Swedish railway network is old, there has been almost no expansion of the network during the past few decades, and more traffic is expected. Therefore, there is currently a demand for more track capacity and, in the short term, the existing network is expected to deliver the increased capacity. The railway operators in the network have a large impact on train delays, and wheel failures are one large contributor of delays. Delays destroy capacity and, therefore, capacityconsuming failures, such as abnormal wheels, need to be minimised. This can be achieved by using appropriate condition monitoring for the wheels on the track to find potential capacity consumers before failures happen. Therefore, the condition of the wheel-rail interface is important, since the state of the wheel influences that of the rail and vice versa. The monitoring of rail profiles is already being performed, but the monitoring of wheel profiles is still in the development phase. This thesis treats the applications and performance assessment of a wheel profile measurement system (WPMS), and presents case studies focusing on its system and measurement performance. The proposed applications concern how the information from the WPMS can be integrated with information from other data sources and with physical models to obtain a true current picture of the wheel behaviour. The thesis investigates the measurement performance of the WPMS by using a paired T-test and a number of quality measures, e.g. the reproducibility and repeatability, the precision-to-tolerance ratio and the signal-to-noise ratio. In conclusion, this thesis shows that the WPMS works well with an expected level of reliability in a harsh climate with respect to its measurement and system performance. By combining other data with the data from the WPMS, potentially abnormal wheels can be found in an early stage if the proposed new maintenance limit for the wheel parameter of the flange height is implemented. Furthermore, through adding a physical model to the process, the real contact condition of the actual wheel-rail interface can be evaluated and measurement deviations can be found. However, the wheel parameters, as well as the entire profile, need a high measurement quality with little variation, which seems to be an issue with respect to the measurement performance when advanced calculations are to be done. Therefore, a new approach for evaluating measurement performance has been developed using established statistical tools and quality measures with predefined acceptance limits; with the help of this approach, one can differentiate between the variation in the measurements originating in the different measurement units and the variation originating in the wheels. This new approach can be applied to judge the measurement performance of wheel profile condition-monitoring systems, and can also be implemented for other condition-monitoring systems to evaluate their measurement performance. Finally, this approach promotes the development of a condition-based maintenance policy by providing more reliable information for maintenance decision makers.

The mining production in Kiruna is heading towards larger depth and it is necessary to prepare for the next generation of underground facilities and new mining methods below the current main level. An important issue is the increasing rock stresses, which follows the ever-increasing depth of mining. This may result in instability of drifts, ramps, shaft and other facilities. The objective of this thesis is to clarify the stress situation in the mine and to state a relationship that could be used for rock mechanical analysis. The first part of the thesis is an appraisal of the results from the rock stress measurements carried out during the 1980's and 1990's. The measured state of stress shows a large variation, which depends on the influence of the mining production, measuring errors, and the heterogeneous nature of the rock mass. Even though, the stress measurements clearly affected by the mining production is sorted out, the variation remains. This means that the stress state in Kiirunavaara is still difficult to interpret. In order to increase the understanding of the natural variation, a literature review and analyses of the stress distribution in the rock mass is given. Because of this uncertainty, the second part presents another approach of handling the problems with the large scatter in the measured state of stress. By doing conceptual numerical analyses and probabilistic sensitivity analyses of underground constructions, the parameters affecting the behavior of the rock mass are studied. The analyses shows that the significance of the variation of the stress state is less than the significance of many other parameters like the stiffness and the strength of the rock mass. The recommendations is therefore, that a geomechanical model of the mine should be developed including for instance, the spatial variation of parameters like Young's modulus and strength of intact rock and joint parameters like number of joint sets, orientation, frequency and filling material. / <p>Godkänd; 2003; 20070218 (ysko)</p>

Open pit mines constitute more than half of global minerals production. Yet most of the large, high-grade, and close to the surface deposits have been depleted or are currently in production. Besides, volatility in commodity prices and stringent environmental regulations limit the up-scaling expansions in large open pits. Consequently, the mines are determined to increase their operational efficiency in order to thrive. This has recently led to major metallurgical improvements in the processing of ores; whereas the improvements in mining of the said ores are relatively overdue in terms of efficiency and technological advancement. This thesis concentrates on the mining activities and their efficiency in open pits with a focus on drilling, blasting, loading, and crushing. As all of these tasks revolve around the fragmentation of run-of-mine ore, their relationships and efficiencies are explored within the context of fragmentation. Fragmentation is a result of complex interactions between rockmass, blasting geometry, explosive, and timing sequence of blast holes. The influence of rockmass and timing sequence on fragmentation and efficiency are explored, as well as the target fragmentation for efficient loading and crushing. Moreover, the techniques for measuring fragmentation are evaluated as to whether they can benefit mines in terms of efficiency. As the circumstances in open pits are essentially site-specific, these issues are addressed as a case study of the Aitik mine in Sweden. The research comprised four elements. First, the influence of rockmass fractures on blast results and downstream efficiency was evaluated via full-scale field trials. The fractures in and around the case study mine were mapped using a photogrammetric technique and six production blasts were adapted to the major fracture sets to evaluate the effect of initiation direction on downstream efficiency. Second, the influence of the timing sequence of blast holes was explored within the theories of stress waves interaction and their consequent effect on fragmentation. Theoretical and numerical solutions were accompanied by six field trials in full-scale to evaluate the influence of short delay times on fragmentation and efficiency. Third, an empirical study was conducted to correlate fragmentation to the efficiency of loading and crushing; this was done to define a target fragmentation for the studied case. Finally, the techniques to assess fragmentation were discussed both quantitatively and qualitatively. The findings indicated that rockmass fractures have a significant influence on the quality of blasts and efficiency of downstream tasks. In the case study mine, adjustments to orientation of drill pattern and initiation direction of blasts suggested that careful experimentation in this regard can yield a favourable initiation direction with respect to existing discontinuities. Finer fragmentation and higher loading efficiencies can be achieved by adapting the blast designs to the existing fractures, which can lead to significant savings in the long run. On the contrary, the influence of stress waves interaction on blast results turned out to be marginal. Neither the theoretical and numerical solutions nor the field trials showed any significant improvements in blast results from short delays. In fact, it was found rather implausible to expect any noticeable improvements by using short delays. The empirical method to evaluate target fragmentation proved useful as well. It was shown that by incorporating different data from various sources in a mine, one can follow the ore from muckpile to loaders and then to crushers. Having a qualitative understanding of the fragmentation, and by developing tools to measure efficiency, one can estimate what fragmentation is most favourable for an efficient operation. Finally, two image-based methods to assess fragmentation were discussed in terms of repeatability and statistical significance. It was found that the scatter in both methods is rather large, introducing a certain ambiguity in representativeness of their results. Admittedly, it was found that in matters of long-term efficiency, the number, size and representativeness of assessed samples are of more importance compared to the accuracy of individual measurements.