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  • 301.
    Christiansson, Rolf
    et al.
    SKB.
    Olsson, Mats
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser.
    Nyberg, Ulf
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Niklasson, Bengt
    Skanska Teknik, Göteborg.
    Studier av sprängskador i Äspö-laboratoriet2005Ingår i: Bergsprängningskommittén Diskussionsmöte BK 2005, Bergsprängningskommittén , 2005, s. 139-152Konferensbidrag (Övrigt vetenskapligt)
    Abstract [sv]

    En ny tunnel med 70 m längd byggdes på 450 m djup i Äspölaboratoriet 2003. Det ställdes speciella krav på begränsning av sprängskadezonens djup med hänsyn till planerade experiment.Tunneln drevs med galleri och bågformad låg pall för att minimera sprängskador i sulan. I huvuddelen av tunneln användes initieringsystemet Nonel MS och LP. I de tre sista salvorna av galleriet testades elektroniksprängkapslar. Skonsamhetsgraden för vägg och tak var normal med en tillåten skadezon på 0,3 m. Däremot tillämpades samma skonsamhetsgrad även för botten. I övrigt användes normal sprängteknik och normala sprängämnen som Dynotex 17 och Dynorex.Arbetet följdes noggrant genom dokumentation av utfört arbete. Vibrationsmätningar utfördes på nära håll samt på stort avstånd, 1,5 km från arbetsplatsen. Språng¬skador har undersökts genom sågning och sprickkartering.Föredraget kommer att presentera projektet, framförallt (1) erfarenheter från vibra¬tionsmätningar av samtliga sprängsalvor (noggrannheten i geofonmätningarna; totala antalet spränghål i salvorna; bomsalvor; avståndet från salvorna och geo¬logiska strukturer), (2) P-vågshastigheten i tunnelns närområde, (3) faktorer som påverkar utvecklingen av sprängskador, och (4) förslag på kontrollåtgärder som kan leda till att begränsa skadezonen i praktiskt tunnelarbete.

  • 302. Christiansson, Rolf
    et al.
    Olsson, Mats
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser.
    Nyberg, Ulf
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Niklasson, Bengt
    Studies of blast damage at the Äspö Hard Rock Laboratory2005Ingår i: 3rd European Federation of Explosives Engineers (EFEE) World Conference on Explosives and Blasting, 2005, s. 425-434Konferensbidrag (Refereegranskat)
  • 303.
    Chryssanthakis, P.
    et al.
    Norwegian Geotechnical Institute.
    Barton, Nick
    Jing, Lanru
    Stephansson, Ove
    Luleå tekniska universitet.
    Modelling the effect of glaciation, ice flow and deglaciation on large faulted rock masses1991Ingår i: Proceedings: GEOVAL-1990, Symposium on Validation of Geosphere Flow and Transport Models, organised by the Swedish Nuclear Power, Organisation for Economic Co-operation and Development , 1991, s. 530-541Konferensbidrag (Refereegranskat)
  • 304.
    Daerga, Per-Anders
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Stephansson, Ove
    Luleå tekniska universitet.
    Sagefors, I.
    Boliden Wp.
    Funnel Store: new concept for large rock caverns1987Ingår i: Large rock caverns: proceedings of the International Symposium, Helsinki, Finland, 25-28 August 1986. / [ed] K.H.O. Saari, Oxford: Pergamon Press, 1987, Vol. 1, s. 479-488Konferensbidrag (Refereegranskat)
  • 305.
    Dandotiya, Rajiv
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Decision support models for the maintenance and design of mill liners2012Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [sv]

    Gruvindustrin är beroende av att deras maskiner fungerar dygnet runt i krävande miljöer. Autogena (AG) kvarnar som används i gruvor och anrikningsverk är exempel på viktiga flaskhalsar när det gäller stillestånd, vilket direkt påverkar produktionen. Insidan av dessa kvarnar är täckta av gummiinfodring för att förhindra slitage av kvarnarna och för att optimera deras kapacitet och malningsförmåga. Eftersom infodringen nöts kontinuerligt på grund av malningen, och produktionsstopp är väldigt kostsamma, måste reparation, underhåll och inspektion av infodringen genomföras vid lämpliga tillfällen. Vid inspektionerna mäts slitaget på infodringen och det är därmed väsentligt att mätutrustningen är både tillräckligt noggrann och så snabb som möjligt för att minska stilleståndskostnaderna och så att rätt underhållsbeslut kan fattas. I denna avhandling har bland annat en metod utvecklats för att välja optimala mätmetoder för denna applikation. Slitaget av infodringen påverkar hela produktionskapaciteten och effektiviteten hos kvarnarna. Därmed påverkar underhållsbesluten om infodring inte bara kostnader för infodring och produktionsförlustkostnader utan även det totala utbytet vilket visar sig i form av variationer i hur mycket värdefull metall som finns i materialet som lämnar kvarnarna. Därför måste hänsyn tas till kvarnarnas prestanda som funktion av tiden, när beslutsmodeller utvecklas för optimala bytesintervaller. Variationer i malmegenskaper påverkar också slitaget av infodringarna och värdet av malmen. Alla dessa parametrar inverkar på kostnads- och utbytesparametrarna. Därför leder ett hänsynstagande av malmegenskaper i livscykelvinstformuleringen (LCPformuleringen) till att effektivare underhållsbeslut kan fattas. En modell för att stödja underhållsbeslut har därför utvecklats för att möta specifika krav från process-, inköps- och underhållsavdelningarna hos gruvföretaget. Livslängden hos olika komponenter i infodringen, på grund av slitage, varierar beroende på malningsprocessen i kvarnarna och de behöver stoppas vid många tillfällen för byte av infodringskomponenter. Dessa stopp är en av huvudorsakerna till stillestånd i kvarnarna vilket ger produktionsförluster som kan minimeras genom en effektiv planläggning av infodringsbytena och optimal gruppering av de detaljer som skall bytas. Denna planläggning är naturligtvis beroende av livslängden på infodringen. Livscykelkostnaden (LCC) kan reduceras ytterligare genom att på ett optimalt sätt välja infodring med längre livslängd. En modell för beslutsstöd har därför utvecklats som grupperar de olika infodringsdetaljerna på ett optimalt sätt vid byten och som med hänsynstagande till att bättre komponenter har ökade inköpskostnader, föreslår med hur mycket de olika komponenterna borde förbättras för att LCC skall minimeras. Denna modell har visat att betydande besparingar kan göras, om modellen tillämpas fullt ut och ersätter nuvarande underhållsstrategier. Systematiska utvärderingsmetoder och parvisa jämförelser har använts vid valet av optimala mätmetoder för geometrimätningar av infodringsdetaljer. Provtagning av tider, korrelationsstudier och simuleringsmetoder har använts vid LCP-optimeringen för att fastställa optimala bytesintervall för infodringen. En ansats som bygger på en totalgenomgång av alla tänkbara bytesalternativ har använts för att fastställa optimala grupperingar av infodringsdetaljer vid byte, och för att ta fram förslag på optimala livslängdsförbättringar på komponenterna.

  • 306.
    Dandotiya, Rajiv
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Mathematical model for optimum replacement interval of grinding mill liners2009Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper presents an approach to decide a cost effective replacement intervals for the liners of a grinding mill used in ore processing plants. The replacement model is based on the detailed analysis of mill performance characteristics, mill failure statistics and maintenance of mill liner. The model formulation for optimum replacement and mill efficiency includes the cost and revenue drivers for the mill. The developed decision model incorporates maintenance cost and monetary gain by doing analysis of production performance of the mill.The developed mathematical model uses the various types of process data i.e. power consumption, mill load, feed flow, metal recovery etc. which is analyzed to establish correlation with life cycle of mill liners. Due to lack of process data for some particular ore types, various techniques such as smoothing, interpolation, simulation and distribution analysis are used to generate the data for the periods for which data is not available. The paper also discusses practical problems encountered while modeling of the real data using classical approach for replacement decisions. The main objective of this paper is to develop a decision support model for taking a cost effective optimum replacement interval for mill liners. A case study was carried out on real data obtained from an ore dressing plant to validate the model.

  • 307.
    Dandotiya, Rajiv
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Banerjee, Rabindra Nath
    Indian Institute of Technology, Kharagpur.
    Ghodrati, Behzad
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Parida, Aditya
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Optimal pricing and terminal location for a rail-truck intermodal service: a case study2011Ingår i: International Journal of Logistics, ISSN 1367-5567, E-ISSN 1469-848X, Vol. 14, nr 5, s. 335-359Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    To be competitive with other modes of transport, the railway needs to be cost-effective. In order to become more competitive in the logistics industry, Indian Railways has taken new initiative to improve their operations in recent years. A rail-truck intermodal transportation service for Indian Railways is described in this paper. The main focus of the present research is to optimize the freight rate and terminal location together, in order to minimize the total shipping cost of truckers while ensuring the targeted profit of the railway. A model has been developed for the determination of the optimal freight rate and the corresponding intermodal terminal location. The key regulators of this model are the price sensitivity of the trucker and profit guarantee for railways. A case study was developed on the Delhi - Mumbai freight corridor. An analysis was performed to gain insight into the trade-offs among shipment cost and terminal locations.

  • 308.
    Dandotiya, Rajiv
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Berglund, Filip
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Increased production systems effectiveness through condition monitoring and prognostics2011Konferensbidrag (Övrigt vetenskapligt)
  • 309. Dandotiya, Rajiv
    et al.
    Fuqing, Yuan
    Kumar, Uday
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Optimal maintenance decision for line reparable units (LRU) for an aircraft system: a conceptual approach2008Ingår i: Quarterly Journal of the Operational Research Society of India (OPSEARCH), ISSN 0030-3887, E-ISSN 0975-0320, Vol. 45, nr 3, s. 291-302Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Maintenance decisions concerning repair of the Line Replaceable Unit (LRU) of an aircraft fleet need to be considered carefully while deciding the phasing out of the fleet. This is important for achieving higher degree of cost effectiveness and fleet availability at desired level. Discard rate and phasing out period for an aircraft fleet are the critical parameters for determining optimum time to stop the maintenance of LRU. The economic value of remaining useful life of an aircraft fleet should be taken into consideration by salvaging the LRU at the end of the phasing out. The paper suggests a methodology to arrive the time that will minimize the total life cycle cost and provide us economic basis to withdraw the maintenance resources. A mathematical model has been developed for the discard rate of aircrafts based on failure rate, mission life and remaining useful life of the aircrafts in the fleet. This will assist in fulfilling the managing demand of LRU while phasing out of the aircraft fleet.

  • 310.
    Dandotiya, Rajiv
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Lundberg, Jan
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Economic model for maintenance decision: a case study for mill liners2012Ingår i: Journal of Quality in Maintenance Engineering, ISSN 1355-2511, E-ISSN 1758-7832, Vol. 18, nr 1, s. 79-97Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Purpose – Wear life of mill liners is an important parameter concerning maintenance decision for mill liners. Variations in process parameters such as different ore properties due to the use of multiple ore types influences the wear life of mill liners whereas random order of processing, processing time and monetary value of different ore types leads to variation in mill profitability. The purpose of the present paper is to develop an economic decision model considering the variations in process parameters and maintenance parameters for making more cost effective maintenance decisions. Methodology/approach – Correlation studies, experimental results and experience of industry experts are used for wear life modeling whereas simulation is used for maximizing mill profit to develop economic decision model. The weighting approach and simulation have been considered to emphasize the contribution of parameters such as ore value and processing time of a specific ore type to a final result. Findings – This study resulted in developing an economic decision support model for mill liner replacement considering the influence of the variation in the process parameters and its affect on maintenance decisions. This study identified the various important process and maintenance parameters and described the influence of variations in the process parameters on decisions model. The results obtained from the model show that an optimum maintenance policy can only not reduce the maintenance cost, but also affect the process performance, which leads to significant improvement in the savings of the ore dressing mill. Originality and Value – The developed model considers the economic influence of ore properties, variation in process parameters and proposed an approach for considering these parameters in decision making which enhance its value in terms of increased mill profit. Practical implications – The proposed economic decision model is practically feasible and can be implemented within the ore dressing mill industries. Using the model, the cost effective maintenance decision can increase the profit of the organization significantly. Paper type – Case study Keywords: Economic model; Replacement decision; Mill liners; Ore properties; Optimization; Process parameters

  • 311.
    Dandotiya, Rajiv
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Lundberg, Jan
    Parida, Aditya
    Nordström, Jakob
    LTU.
    A systematic evaluation of devices for measuring abrasive wear of mill liners2009Ingår i: 22nd International Congress on Condition Monitoring and Diagnostic Engineering Management: COMADEM 2009 ; June 9 - 11, 2009, San Sebastian, Spain, Miramar Palace / [ed] Aitor Arnaiz, Eibar: Fundaci n Tekniker , 2009, s. 419-427Konferensbidrag (Refereegranskat)
    Abstract [en]

    Inspection of the liner wear in the mill of an ore dressing plant is one of the critical parameters in the context of mill downtime and production performance. The total downtime cost during measurement can be reduced by a significant fraction by using appropriate measurement devices. Due to the different quality dimensions of a measuring device, e.g. the cost, accuracy, reliability and accessibility, it is necessary to select an appropriate device based on the specific needs of the industry. Customer satisfaction is perhaps the most important performance measure for the service quality of the device, and therefore this paper provides an approach to define the customer satisfaction with reference to the mentioned quality dimensions. The main aim of this paper is to determine a unified measure or quality index for the service quality of the measurement device across all the dimensions. Each quality index will then correspond to the total predicted usability of the particular measurement method based on the industry needs. Furthermore, this study also discusses the advantages and disadvantages of existing measurement methods and proposes an indirect measurement method to reduce the downtime during inspection.

  • 312.
    Dandotiya, Rajiv
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Lundberg, Jan
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Wijaya, Andi
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Evaluation of abrasive wear measurement devices of mill liners2011Ingår i: International Journal of COMADEM, ISSN 1363-7681, Vol. 14, nr 2, s. 3-17Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Measurement of the liner wear in the mill of an ore dressing plant is one of the critical parameters in the context of mill downtime and production performance. The total downtime cost during measurement can be reduced by a significant fraction by using appropriate measurement devices. Due to the different quality attributes of a measuring device, e.g. the cost, accuracy, reliability and accessibility, it is necessary to select an appropriate device based on the specific needs of the industry. The main aim of this study is to determine a unified measure or quality index for the service quality of the measurement device across selected attributes. Each quality index will then correspond to the total predicted usability of the particular measurement method based on the industry needs. Furthermore, this study includes test of selected measurement methods and discusses the advantages and disadvantages for the same. It also proposes a new concept of an indirect measurement method to reduce the downtime during inspection.

  • 313.
    Danielsson, Markus
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Ghosh, Rajib
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Navarro Miguel, J.
    Universidad Politechnica de Madrid.
    Johansson, Daniel
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Schunnesson, Håkan
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Utilizing production data to predict operational disturbances in sublevel caving2017Ingår i: Mine Planning and Equipment Selection (MPES 2017): Proceeding of the 26th International Symposium on Mine Planning and Equipment Selection Luleå, Sweden, August 29-31, 2017 / [ed] Behzad Ghodrati, Uday Kumar, Håkan Schunnesson, Luleå: Luleå tekniska universitet, 2017, s. 139-144Konferensbidrag (Refereegranskat)
  • 314.
    Danielsson, Markus
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Johansson, Daniel
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Schunnesson, Håkan
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    The Influence of Blast Fragmentation on Loadability in Sublevel Caving2018Ingår i: Proceedings of the forty-forurth annual conference on explosives and blasting technique / [ed] Kevin Hachmeister, 2018Konferensbidrag (Refereegranskat)
    Abstract [en]

    In sublevel caving, blasted material flows gravitationally into the drawpoint from above in a periodical manner. This type of flow behavior entails muck pile conditions that are variable along the course of extraction. The effect of this variability on the LHD (Load-Haul-Dump) operation in terms of loading efficiency and ability to undermine the blasted ring is not fully understood as of today. This paper presents results from a field test in LKABs Malmberget mine in Sweden, where the influence of fragmentation on the loading operation has been studied in detail. Drawpoint filming was conducted for extraction of two rings equivalent of roughly 10000 metric tons (~9842 long tons) of material each. The analysis includes fragmentation measurements, muck pile classification, and general estimations in terms of loadability. Further, an evaluation of LHD machines from two different manufacturers was conducted to identify and highlight differences. The results show that fragmentation, muck pile compactness, and flow characteristics are all interdependent. Flow disturbances and the subsequent loading of compacted fine material in the back of the ring have been identified as the main reason for occurring problems and prolonged digging times. However, the ability to sufficiently undermine the blasted ring has been identified to primarily depend on digging depth which is only observed to be high during flow disturbances. An absence of flow disturbances seem to promote high loading efficiency but simultaneously limit the maximum digging depth. A mid-range particle size distribution with a low amount of fines has proven beneficial for overall loading efficiency. The various LHDs employed showed significant variations in terms of ability to handle difficult loading situations (e.g. compactness, boulders, etc.).

  • 315.
    Darbari, Jyoti D.
    et al.
    Department of Operational Research, University of Delhi, India.
    Agarwal, Vernika
    Department of Operational Research, University of Delhi, India.
    Yadavalli, Venkata S.S.
    Department of Industrial and Systems Engineering, University of Pretoria, South Africa.
    Galar, Diego
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Jha, Prakash C.
    Department of Operational Research, University of Delhi, India.
    A multi-objective fuzzy mathematical approach for sustainable reverse supply chain configuration2017Ingår i: Journal of Transport and Supply Chain Management, ISSN 2310-8789, E-ISSN 1995-5235, Vol. 11, artikel-id a267Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Background: Designing and implementation of reverse logistics (RL) network which meets the sustainability targets have been a matter of emerging concern for the electronics companies in India.

    Objectives: The present study developed a two-phase model for configuration of sustainable RL network design for an Indian manufacturing company to manage its end-of-life and endof-use electronic products. The notable feature of the model was the evaluation of facilities under financial, environmental and social considerations and integration of the facility selection decisions with the network design.

    Method: In the first phase, an integrated Analytical Hierarchical Process Complex Proportional Assessment methodology was used for the evaluation of the alternative locations in terms of their degree of utility, which in turn was based on the three dimensions of sustainability. In the second phase, the RL network was configured as a bi-objective programming problem, and fuzzy optimisation approach was utilised for obtaining a properly efficient solution to the problem.

    Results: The compromised solution attained by the proposed fuzzy model demonstrated that the cost differential for choosing recovery facilities with better environmental and social performance was not significant; therefore, Indian manufacturers must not compromise on the sustainability aspects for facility location decisions.

    Conclusion: The results reaffirmed that the bi-objective fuzzy decision-making model can serve as a decision tool for the Indian manufacturers in designing a sustainable RL network. The multi-objective optimisation model captured a reasonable trade-off between the fuzzy goals of minimising the cost of the RL network and maximising the sustainable performance of the facilities chosen.

  • 316.
    Delghandi, Sayed Hamed
    et al.
    Tarbiat Modares University.
    Sayadi, Ahmad Reza
    Tarbiat Modares University.
    Hoseinie, Hadi
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Reliability analysis of the loading system of hydraulic excavator2014Konferensbidrag (Refereegranskat)
    Abstract [en]

    Hydraulic excavators are widely used in mining and construction. They have an important role in mine loading cycle. These machines have three major parts: work equipment, upper structure and lower structure. The work equipment that is for digging and loading includes boom, arm and bucket. Because of the operation of the work equipment, it has got more failures in comparison with other parts. In this paper reliability modeling of work equipment according to the method of analytic solution of the proposed model has been made. After estimating of model parameters, system failure rate has been calculated and failure behavior is assessed. The reliability of work equipment system reduces to 80% after 30 hours of operation and it reach zero after about 360 hours. The failure rate increases at a decreasing rate and after 360 hours it will be at a rate of 0.021.

  • 317.
    Delsing, Jerker
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, EISLAB.
    Ekman, Jonas
    Mäkitalo, P.
    Niska, Stefan
    Wisten, Åke
    Sources and propagation of eectromagnetic transients in railway systems, S01-3915/08. Final Report2005Rapport (Övrigt vetenskapligt)
    Abstract [en]

    The railway system is continuously being updated. Upgrading axle loads, introducing new engines with increasing power needs and advanced motor control give unwanted electromagnetic consequences for electronic-, telecommunication-, and signalling systems along the track. This can, for example, lead to failure in detector systems and traffic control systems and increased cost due to corrective maintenance. This research project was initiated with the purpose of understanding origin and propagation of radiated and conducted electromagnetic transients in the railway system. To investigate the problem of radiated and conducted electromagnetic interference, it has been necessary to develop new measuring methods. Measurements have been conducted to determine if the more sensitive low voltage systems are influenced by higher voltage systems. An existing electromagnetic modeling tool has been utilized, to model crosstalk between the rails and the overhead line catenary system, and modified to incorporate a combination of two- and three- dimensional models to reduce time and space complexity. The resulting simulation environment can be used to analyze possible sources of electromagnetic disturbances in the coexisting signaling circuitry of today, and to reduce the influence of these sources. This gives a new application of the measurement method and further development of a simulation tool. One of the objectives in this project has been to find out the tolerance of the low voltage detector systems in presence of the higher voltage system used in the railways. One of the conclusions is that correct installation is important and that failure to comply with installation procedures results in high electromagnetic interference. There is no correlation between the presence of trains and randomly occurring disturbances.

  • 318.
    D'Emilia, G.
    et al.
    University of l'Aquila, L'Aquila, Italy.
    Gaspari, A.
    University of l'Aquila, L'Aquila, Italy.
    Galar, Diego
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Improvement of measurement contribution for asset characterization in complex engineering systems by an iterative methodology2018Ingår i: International Journal of Service Science, Management, Engineering, and Technology, ISSN 1947-959X, Vol. 9, nr 2, s. 85-103, artikel-id 4Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The evolution of systems based on the integration of Internet of Things (IoT) and Cloud computing technologies requires resolute and trustable management approaches, to let the industrial assets thrive and avoid losses in efficiency and, thus, profitability. In this article, a methodology based on the evaluation of the measurement uncertainty is proposed, which is able to suggest possible improvement paths and reliable decisions. The approach is based on the identification of subsequent tasks that should be fulfilled, also in a recursive way. Its application in the field, for the identification of the vibration and acoustic emission signatures of highly-performance machining tools, allows directing future actions to increase the potentiality of proper management of the information provided by measurements. In a complex scenario, characterized by many devices and instruments, the compliance with the procedures for measurement accuracy has proven to be a useful support.

  • 319.
    Desai, Ajay
    et al.
    CQ University.
    Chattopadhyay, Gopinath
    CQ University.
    Clegg, Richard
    CQ University.
    Howie, Alex
    QR National Ltd, Brisbane.
    Larsson-Kråik, Per-Olof
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Prakash, Braham
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Experimental setup and methodology for the analysis of rail lubricant effectiveness2011Ingår i: Proceedings of the 24th International Congress on Condition Monitoring and Diagnosis Engineering Management: COMADEM 2011 / [ed] Maneesh Singh; Raj B.K.N. Rao; J.P. Liyanage, COMADEM International, 2011, s. 592-598Konferensbidrag (Refereegranskat)
    Abstract [en]

    Rail and wheel wear is a complex problem. Lubrication plays an important role in reducing wear and enhancing asset life. Curves and switches are the areas of major challenges. Tight curves when running dry shows wear rates higher to rapid wear, increased maintenance costs and non-availability of track due to maintenance or replacement. The economic analysis based on cut-off radius, lubricants and applicators takes a very long time using field data. Rail operators often face difficulties when selecting lubricants. Lubricant manufactures use different test standards when specifying lubricant properties. Four-ball test fails to give a meaningful indication of lubricant performance. The result is often a complex decision problem in ranking different lubricants under a particular axel load. An appropriate selection of lubricant for a particular rail application can give financial returns and extension of asset life. An experimental set up has been proposed in this paper. The experimental results are expected to be used for development of models on effective lubrication. This paper proposes experimental setups and methodology for analysis of lubrication effectiveness in heavy haul lines. Theories along with existing research to date relating to ranking of lubricants for rail applications and a criterion for the ranking is discussed. An analysis is carried out to compare lubricants used in Australian Heavy Haul lines based on manufacturer supplied specifications and experimental results.

  • 320.
    Diez-Olivan, Alberto
    et al.
    TECNALIA, Donostia-San Sebastián, Spain.
    Del Ser, Javier
    TECNALIA, Donostia-San Sebastián, Spain. Department of Communications Engineering, University of the Basque Country, Bilbao, Spain. Basque Center for Applied Mathematics (BCAM), Bilbao, Bizkaia, Spain.
    Galar, Diego
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik. TECNALIA, Donostia-San Sebastián, Spain.
    Sierra, Basilio
    Department of Computer Sciences and Artificial Intelligence, University of the Basque Country (UPV/EHU), Donostia-San Sebastián, Spain.
    Data Fusion and Machine Learning for Industrial Prognosis: Trends and Perspectives towards Industry 4.02018Ingår i: Information Fusion, ISSN 1566-2535, E-ISSN 1872-6305, Vol. 50, s. 92-111Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The so-called “smartization” of manufacturing industries has been conceived as the fourth industrial revolution or Industry 4.0, a paradigm shift propelled by the upsurge and progressive maturity of new Information and Communication Technologies (ICT) applied to industrial processes and products. From a data science perspective, this paradigm shift allows extracting relevant knowledge from monitored assets through the adoption of intelligent monitoring and data fusion strategies, as well as by the application of machine learning and optimization methods. One of the main goals of data science in this context is to effectively predict abnormal behaviors in industrial machinery, tools and processes so as to anticipate critical events and damage, eventually causing important economical losses and safety issues. In this context, data-driven prognosis is gradually gaining attention in different industrial sectors. This paper provides a comprehensive survey of the recent developments in data fusion and machine learning for industrial prognosis, placing an emphasis on the identification of research trends, niches of opportunity and unexplored challenges. To this end, a principled categorization of the utilized feature extraction techniques and machine learning methods will be provided on the basis of its intended purpose: analyze what caused the failure (descriptive), determine when the monitored asset will fail (predictive) or decide what to do so as to minimize its impact on the industry at hand (prescriptive). This threefold analysis, along with a discussion on its hardware and software implications, intends to serve as a stepping stone for future researchers and practitioners to join the community investigating on this vibrant field.

  • 321.
    Digby, P.J.
    et al.
    Luleå tekniska universitet.
    Nilsson, L.
    Luleå tekniska universitet.
    Bergman, B-O
    Luleå tekniska universitet.
    Computer simulation of blast-induced vibration, fracture and fragmentation processes in brittle rocks1983Ingår i: First international symposium on rock fragmentation by blasting, August 23-26, 1983, Luleå university of technology / [ed] Roger Holmberg; Agne Rustan, Luleå: Luleå tekniska universitet, 1983, Vol. 1, s. 393-406Konferensbidrag (Refereegranskat)
  • 322.
    Dineva, Savka
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Boskovic, Mirjana
    LKAB.
    Evolution of seismicity at Kiruna Mine2017Ingår i: Deep Mining 2017: Eighth International Conference on Deep and High Stress Mining / [ed] J Wesseloo, Perth: Australian Centre for Geomechanics , 2017, s. 125-140Konferensbidrag (Refereegranskat)
    Abstract [en]

    Kiirunavaara (Kiruna) iron ore mine owned by LKAB (Sweden) is one of the largest underground mines. Miningstarted in 1898 as an open pit mine. In mid-1950, the mine started a transition to underground mining andpassed to only underground mining in 1962. More substantial problems with seismicity started in 2007-2008when the deepest mining level was 907 m (ca. 670 m below surface). By 2016, the mining production is at1,022–1,079 m Level (ca. 785–845 m below surface). More than one billion tonnes of ore have been extractedsince the beginning of mining. The average yearly production in recent years is 28 million tonnes.By 2016 the mine has the largest underground seismic system in the world with 204 operational geophones.The number of the sensors (geophones with natural frequencies of 4.5, 14, and a few of 30 Hz) changed withthe increasing of production depth. The major stages with seismic system upgrades are: August 2008–June2009 with 112 installed geophones, and July 2012–September 2013 with 95 installed geophones. During2016–2017 it is planned to install some additional 45 geophones.The study was carried out to identify some trends in seismicity as the mining goes deeper and to find thecorrelation with some main controlling parameters – volume and depth of the production in order to obtaininformation for future seismic hazard and risk analysis. Custom made applications within mXrap were utilisedto carry out the spatial variations of seismicity.The analysis showed substantial difference between the seismicity in the three studied blocks – 15/16, 28/30,and 33-37/34, with the weakest seismic activity in Block 15/16 (Mmax 1.6, maximum observed magnitude),followed by Block 28/30 (Mmax 2.2), and then largest seismicity in Block 33-37/34 (Mmax 2.2). The dailyseismicity rate increased substantially through the years only for Block 33-37/34. The seismicity correlatesstrongly with the production depth. In general a straightforward correlation between the production volumeand number of larger events (M > 0) was not found for the three studied blocks, assuming there are otherfactors affecting the seismicity, e.g. geological structures, areas with contrast in geomechanical properties,etc. The spatial variations of some seismic source parameters were traced for varying periods of time,depending on the major production stages (opening of new levels, full production, closing) for the threeblocks. The distributions of the cumulative seismic energy showed a maximum around and below theproduction. The cumulative seismic moment and number of events in most cases showed a maximum aroundand above the production, indicating caving in these areas. The static stress drop shows the largest valuesaround and below the production on the footwall side, corresponding also to the areas with increased stress.The energy index showed increased stresses in the same areas (EI > 1).This study is only the first overview of the seismicity in Kiruna Mine. For seismic hazard assessment and riskanalysis further more detailed studies with smaller time intervals need to be carried out to obtain more precisecorrelations between the seismic parameters and the production volume and depth, and other possible factorsaffecting seismicity (geological structures, areas with contrast geomechanical properties, etc.).

  • 323.
    Dineva, Savka
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Mihaylov, Dimitar
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Hansen-Haug, Jouni
    Lundin Mining.
    Nyström, Anders
    Boliden AB.
    Woldemedhin, Biruk
    LKAB.
    Local seismic systems for study of the effect of seismic waves on rock mass and ground support in Swedish underground mines (Zinkgruvan, Garpenberg, Kiruna)2016Ingår i: Proceedings of the 8th International Symposium on Ground Support in Mining and Underground Construction / [ed] E . Nordlund, T.H. Jones and A. Eitzenberger, 2016Konferensbidrag (Refereegranskat)
    Abstract [en]

    Three local seismic systems were installed by August 2015 in deep underground mines in Sweden – Zinkgruvan Mine (Lundin Mining AB), Garpenberg Mine (Boliden AB), and Kiirunavaara Mine (LKAB) as part of a project for developing new methods for Evaluating the Rock Support Performance (ERSP, Vinnova). The areas were chosen within the most probable volumes where large rockbursts can be expected. The local systems were installed at mine levels between 730 and 1150 m in different mines. The horizontal extend of each instrumented areas is between 70 and 100 m. The seismic system in each mine is a combination of uni-axial and three-axial 4.5 Hz geophones installed on the surface, in shallow (~0.5 m) and deeper (6-9 m) boreholes in profiles across drifts. These profiles are in close proximity to profiles with extensometers, instrumented bolts, and observation holes. The seismic systems are manufactured and installed by the Institute of Mine Seismology (IMS). The aim of the seismic systems is to record the seismic events that occur in the vicinity of the instrumented areas and provide valuable data about the variability of seismic waveforms around the underground openings and changes when seismic waves approach them. Data is used to study: 1) the attenuation/decrease of the maximum ground velocity (PPV) with the distance, especially at small distances; 2) site effects, including maximum amplitudes, predominant frequency, and duration of the seismic signals, 3) the attenuation/amplification of the seismic waves approaching the underground opening. The final aim is to obtain new information that can be used for improved requirements for the rock support design in rockburst prone areas.The installation of the seismic systems started in May 2015 (Zinkgruvan Mine) and was completed by August 2015. They run mostly in triggered mode with initial automatic arrival time picking and source parameter calculation and subsequent manual processing of seismic event of interest. More than 200,000 seismic events with magnitude from -4.5 to 2.0 were recorded by December 2015. At present only a small portion of all data was processed manually and the procedures for processing of the events were developed on this subset. The first results from the monitoring showed that there are differences in the amplitudes and shape of the seismic signals recorded by the sensors installed in deeper borehole (behind the most blast-damaged zone (6 – 9 m)) and close to the surface (0.5 m) or on the surface of the openings. There are also differences between the waveforms recorded on the walls and the roof along the same profiles or on nearby profiles. Data from the investigated rockbursts showed maximum velocity recorded from a seismic events at close distances with magnitude larger than 0.5 in the order of 10 cm/s with clipping levels 10 – 20 cm/s.

  • 324.
    Doe, T.W.
    et al.
    Lawrence Berkeley Laboratory.
    Hustrulid, W.A.
    Colorado School of Mines, Golden.
    Leijon, Bengt
    Luleå tekniska universitet.
    Ingevald, K.
    Swedish State Power Board.
    Strindell, L.
    Swedish State Power Board.
    Carlsson, H.
    Swedish Nuclear Fuel Supply Co.
    Results and conclusions of stress measurements at Stripa1983Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper describes the results of stress measurements at Stripa, compares the results obtained by different techniques, and recommends a stress measurement program for a hard rock repository site. The state of stress at the Stripa Mine has been measured both in a 381-m-deep hole drilled from the surface and in holes drilled from the drifts underground. Hydraulic fracturing and several overcoring methods have been used (Lulea triaxial gauge, CSIRO gauge, USBM gauge, Swedish State Power Board deep-hole Leeman triaxial gauge). The results of overcoring and hydraulic fracturing agree well, particularly for the magnitude and orientation of the greatest stress. A recommended program for stress measurement at a repository site would include hydraulic fracturing and deep-hole overcoring in a deep hole drilled from surface, and overcoring (Lulea gauge and USBM gauge) and hydraulic fracturing from holes drilled from underground openings when access is available. Propagation of the hydraulic fractures should be monitored acoustically to determine their location and orientation.

  • 325.
    Doe, T.W.
    et al.
    Lawrence Berkeley Laboratory.
    Hustrulid, W.A.
    Colorado School of Mines, Golden.
    Leijon, Bengt
    Luleå tekniska universitet.
    Ingvald, K.
    Statens Vattenfallsverk.
    Strindell, L.
    Statens Vattenfallsverk.
    Determination of the state of stress at the Stripa Mine, Sweden1982Ingår i: Workshop on Hydraulic Fracturing Stress Measurements: Proceedings / [ed] M. D. Zoback ; B. C. Haimson, Menlo Park, Calif, 1982Konferensbidrag (Refereegranskat)
    Abstract [en]

    The state of stress at the Stripa Mine has been measured both in a 381-m-deep hole drilled from the surface and in holes drilled from the drifts underground. Hydraulic fracturing and several overcoring methods have been used (Lulea triaxial gauge, CSIRO gauge, USBM gauge, Swedish State Power Board deep-hole Leeman triaxial gauge). Propagation of the hydraulic fractures underground was monitored acoustically in an attempt to determine the location and orientation of the fractures. The results of overcoring and hydraulic fracturing agree well, particularly for the magnitude and orientation of the greatest stress. The hydraulic-fracturing data were interpreted using first-breakdown pressures and tensile-strength values determined using statistical fracture mechanics. Shut-in pressure values were obtained from semi-logarithmic plots of the post-breakdown pressure decay and from reopening the fractures at low pumping rates.

  • 326.
    Duarte, Margarida Taborda
    Luleå tekniska universitet.
    Modelling the microstructure, the mechanical response of rock material and the relationship between them2003Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Rock material heterogeneity is one of most important intrinsic properties of geological materials. The need to quantify and model this heterogeneity is a key point for the prediction of the rock fragmentation behaviour through simulation. In this thesis both microstructure and mechanical heterogeneity are analysed. In both characterizations, statistical modelling is used as the main tool. This thesis is organized in two parts. The first part consists in overview of the approach used to quantify, model and investigate rock material heterogeneity. Moreover, a literature reviews about the influence the microstructure properties in the strength and deformability behaviour of granites is presented. Shortly, the main conclusions obtained in this thesis are: (i) after testing several statistical models it is concluded that Weibull distribution function is the most appropriate one for modelling the grain size and grain shape of the microstructure. The parameters for this modelling are given. Concerning grain orientation none of the models is able to model it as they to show a trend to anisotropy while the rock is isotropic; (ii) it is proved that even when a small number of mechanical tests are available the mechanical heterogeneity can be estimated in a reliable way. The confidence intervals for the homogeneity index of granites for unconfined compression, Young's modulus and Poisson's ratio are given. The second part of this thesis consists in four appended papers listed bellow. The first two papers (A and B) deal with the modelling of the microstructure and mechanical heterogeneity using the weakest link theory. The paper C concerns the analysis of the correlation between the microstructure and mechanical properties of aggregates.

  • 327.
    Duarte, Margarida Taborda
    et al.
    Luleå tekniska universitet.
    Lindqvist, Per-Arne
    Kou, S.Q.
    Luleå tekniska universitet.
    Miskovsky, Karel
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser.
    Quantitative characterization of rock material for modelling of microstructure2003Ingår i: Konferens i mineralteknik / [ed] Marianne Thomaeus; Eric Forssberg, Föreningen Mineralteknisk Forskning / Swedish Mineral Processing Research Association , 2003Konferensbidrag (Övrigt vetenskapligt)
  • 328.
    Duarte, Margarida Taborda
    et al.
    Geomaterials Research, Cnh da Figueira.
    Liu, H.Y.
    Luleå tekniska universitet.
    Kou, S.Q.
    Luleå tekniska universitet.
    Lindqvist, Per-Arne
    Miskovsky, Karel
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser.
    Microstructural modeling approach applied to rock material2005Ingår i: Journal of materials engineering and performance (Print), ISSN 1059-9495, E-ISSN 1544-1024, Vol. 14, nr 1, s. 104-111Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The importance of the microstructural parameters in rock mechanical behavior has been investigated by several authors. Moreover, the Weibull statistical model has been used to characterize the heterogeneity of several materials on the basis of the concept that the microscopic defects within the material determine their mechanical strength. The modeling of different rocks is a topic that is fundamental for the prediction of rock fragmentation. In this article, the analysis of rock microstructure is performed using the microstructural modeling approach, which consists of the simplification, quantification, and modeling of the main properties of rock microstructure. The grain size, grain shape, and microcracks are modeled by means of statistical density functions, namely, Cauchy, chi-squared, exponential, extreme value, gamma, Laplace, normal, uniform, and Weibull. It is found that the Weibull distribution is the most appropriate statistical model of the grain size and grain shape, when compared with the other eight statistical models. Regarding microcracks, the results show that the gamma distribution is the most appropriate model. The Weibull and gamma distributions are then used to analyze the heterogeneity of the microstructure. This is done by comparison of the statistical models of each microstructural property evaluated in several thin sections of the same rock. It is found that with respect to grain size and grain shape, the rock is homogeneous, while the size distribution of the microcracks shows a clear trend toward less homogeneity. The microstructural modeling approach is important for modeling, characterizing, and analyzing the microstructure of rock material. Among other applications, it can be used to explain differences in the mechanical behavior obtained in testing several specimens.

  • 329.
    Duvnjak, Ivan
    et al.
    University of Zagreb, Croatia.
    Damjanović, Domagoj
    University of Zagreb, Croatia.
    Sabourova, Natalia
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Grip, Niklas
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
    Ohlsson, Ulf
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Elfgren, Lennart
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Tu, Yongming
    School of Civil Engineering, Southeast University, Nanjing, China.
    Damage Detection in Structures – Examples2019Ingår i: IABSE Symposium 2019: Towards a Resilent Built Environment - Risk and Asset Management, 2019Konferensbidrag (Refereegranskat)
    Abstract [en]

    Damage assessment of structures includes estimation of location and severity of damage. Quite often it is done by using changes of dynamic properties, such as natural frequencies, mode shapes and damping ratios, determined on undamaged and damaged structures. The basic principle is to use dynamic properties of a structure as indicators of any change of its stiffness and/or mass. In this paper, two new methods for damage detection are presented and compared. The first method is based on comparison of normalised modal shape vectors determined before and after damage. The second method uses so-called 𝑙1-norm regularized finite element model updating. Some important properties of these methods are demonstrated using simulations on a Kirchhoff plate. The pros and cons of the two methods are discussed. Unique aspects of the methods are highlighted.

  • 330.
    Edberg, Jonas
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
    Larsson, Dan
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Lindgren, Lars-Erik
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Material- och solidmekanik.
    Simulation of braking of railway wheel2003Rapport (Övrigt vetenskapligt)
    Abstract [en]

    LKAB has tried new iron ore wagons for the 30 tonnes axle load. They got problems with cracking and material removal from the rim of the wheels during the tests. Martensite, which is more prone to cracking than other microstructures, was found at these locations. The initial material microstructure is supposed to contain no martensite. The purpose of this investigation is to find whether the thermal cycle due to braking, possibly with assistance of the mechanical load, can cause martensite formation

  • 331.
    Edelbro, Catrin
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Bestämning av bergmassans hållfasthet med hjälp av bergkaraktärisering2004Ingår i: Bergmekanikdag 2004 Föredrag, SweBeFo , 2004, s. 41-51Konferensbidrag (Övrigt vetenskapligt)
    Abstract [sv]

    Kunskapen om bergmassans lastbärande förmåga är viktig vid utformning av alla former av underjordsanläggningar. I denna studie har befintliga karaktäriserings- och klassificeringssystem samt brottkriterier kritiskt granskats med avseende på tillämpbarhet för att bedöma hållfastheten av hårda bergmassor. De viktigaste styrande faktorerna/parametrarna för bergmassans hållfasthet har identifierats och beskrivits. Befintliga brottkriterier har utvärderats genom en kritisk fallstudie, uppdelad i två delar. Den första delen består av ett s.k. "Round Robin Test", där ett antal bergmekaniker har, baserat på samma indata, uppskattat hållfastheten med hjälp av några utvalda karaktäriseringssystem och brottkriterier. Två fall studerades - en pelare från Laisvallgruvan och en fiktiv bergmassa med en djupt belägen tunnel. Den andra delen av fallstudien behandlar hållfasthetsbedömning av ett storskaligt test från Stripa. Fallstudien nyttjades för att identifiera vilka brottkriterier som är robusta, vilka parametrar/faktorer som är viktiga samt vilka faktorer som i de befintliga systemen/kriterierna är känsliga för variationer och/eller har en beskrivning som ger en stor spridning i resultatet. Baserat på fallstudierna identifierades de mest användbara och robusta kriterierna och karaktäriseringssystemen för uppskattning av bergmassans hållfasthet.

  • 332.
    Edelbro, Catrin
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Different approaches for simulating brittle failure in two hard rock mass cases: a parametric study2010Ingår i: Rock Mechanics and Rock Engineering, ISSN 0723-2632, E-ISSN 1434-453X, Vol. 43, nr 2, s. 151-165Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    One of the aims of rock mechanics analysis is to predict fallouts in underground excavations. The objective of this paper was to study the relative importance of different strength parameters and their significance on the simulation of brittle failure and fallouts. This work was conducted as a parametric study, using numerical modelling and a number of approaches. The results were compared with observed fallouts. More obvious and distinct shear bands could be observed with decreased element sizes close to, and at, the boundary. The maximum shear strain was the most reliable indicator for fallout prediction. The results of the (instantaneous) cohesion softening friction softening models were sensitive to changes of the peak strength parameters and less sensitive to variations in residual parameters. The result from the cohesion-softening friction-hardening (CSFH) model, when using a peak cohesion equal to the intact rock strength, best captured the observed rock behaviour.

  • 333.
    Edelbro, Catrin
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Evaluation of rock mass strength criteria2004Licentiatavhandling, monografi (Övrigt vetenskapligt)
    Abstract [en]

    Knowledge of the rock mass behaviour in general, the failure process and the strength in particular, is important for the design of all kinds of underground excavations. One of the most common ways of estimating the rock mass strength is by using a failure criterion. The existing rock mass failure criteria are stress dependent and often include one or several parameters that describe the rock mass properties. These parameters are often based on classification or characterisation systems. A comprehensive literature review of existing classification/characterisation systems and rock mass failure criteria has been performed. As the application of this licentiate thesis is for hard rock masses some limitations have been stated on the systems and criteria. The limitations of the classification/ characterisation systems are that they should present a result that is relevant for the strength, give a numerical value, have been used after the first publication and be applicable to hard rock masses. Based on the literature review, it was concluded that the uniaxial compressive strength, block size and shape, joint strength and a scale factor are the most important parameters that should be used when estimating the rock mass strength. Existing rock mass failure criteria and classification/characterisation systems have been evaluated through the use of case studies. The aim of the case studies was to identify robust systems and criteria, parameters having the strongest impact on the calculated rock mass strength and those giving a large interval of the result. The case study revealed that the rock mass quality (Q-system), rock mass Number (N-system), Rock Mass index (RMi) system, Yudhbir – Rock Mass Rating (RMR76) and Hoek-Brown – Geological Strength Index (GSI) seem to be the most suitable systems and criteria to use when determining the rock mass strength. None of the systems or criteria complies with the requirements of a method to determine the rock mass strength and a better rock mass strength estimation method should be developed. This requires more case histories where the determined/estimated rock mass strength from the criteria/systems can be compared to the measured/determines rock mass strength.

  • 334.
    Edelbro, Catrin
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Numerical modelling of observed fallouts in hard rock masses using an instantaneous cohesion-softening friction-hardening model2009Ingår i: Tunnelling and Underground Space Technology, ISSN 0886-7798, E-ISSN 1878-4364, Vol. 24, nr 4, s. 398-409Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The work presented in this paper focuses on compressive stress-induced brittle fallouts in hard rock masses, which are massive or sparsely fractured and subjected to intermediate to high in situ stresses. The results of numerical modelling, using a linear-elastic, brittle plastic material model with cohesion-softening friction-hardening (CSFH) behaviour, were compared with observed fallouts for six cases. The objective was to study how well the results of a CSFH model agrees with observed fallouts with respect to location, depth, and shape. All six cases were well documented with respect to virgin stresses, fallout characteristics, rock mass properties, and rock behaviour. The modelling results showed that shear strain localization (shear bands) developed for all cases. The depth of the intersected shear bands were used as a fallout indicator. Furthermore, the location and shape of the observed fallouts could be predicted fairly accurately. The predicted fallout depth was in good agreement with observed fallouts for three of the cases. Using both yielded elements and intersecting shear bands as fallout indicators results in a better prediction of fallout than using just one indicator.

  • 335.
    Edelbro, Catrin
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Observations and modelling of failure of hard rock masses2007Ingår i: Deep Mining 07: proceedings of the fourth International Seminar on Deep and High Stress Mining, 7-9 November 2007, Perth, Australia / [ed] Yves Potvin, Perth, W.A: Australian Centre for Geomechanics, 2007, s. 81-94Konferensbidrag (Refereegranskat)
    Abstract [en]

    The objective of this paper is to run field data, without modification, for a number of case studies in different numerical models to find the best non-calibrated approach. The purpose of the comparison is to identify which frequently used approach gives the best agreement with the observed fallouts with respect to location, depth, shape, and extent. All of the five case studies are situated in hard rock masses that are massive or sparsely fractured, at depths of 630-965 m below surface. The observed fallouts are compared with the results from numerical models in Examine2D and Phase2D. None of the studied approaches give perfect agreement with the actual fallouts. This study demonstrates that when rock mass strength parameters are defined by either the Hoek-Brown or the Mohr-Coulomb criterion, the elastic and elastic-perfectly plastic models reasonably well predict actual fallout depth, although the extent of fallout is exaggerated and the shape incorrect. Therefore, a precise estimation can not be expected. When using the m=0 approach, the results were in poor agreement with the observed fallout. The fallouts are significantly overestimated when applying the brittle-plastic models using instantaneous softening by cohesion and friction or cohesion weakening.

  • 336.
    Edelbro, Catrin
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Observations and modelling of fallouts of hard rock masses2007Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    The objective of this paper is to apply field data, without modification, for a number of case studies in different numerical models to find the best non-calibrated approach. The purpose of the comparison is to identify which of a number of well-known and frequently used approaches to failure prediction, that gives the best agreement with the observed fallouts with respect to location, depth, shape, and extent. Four case studies are presented which all are situated in hard rock masses that are massive or sparsely fractured, at depths of 630-965 m below surface. The observed fallouts are compared with the results from five numerical models in Examine2D and Phase2D by studying (i) strength factors (SF) and yielded elements and (ii) volumetric and (iii) maximum shear strains. This study demonstrates that when the rock mass strength parameters are defined by either the Hoek-Brown or the Mohr-Coulomb criterion the predicted fallout depth by the SF and yielded elements resulted in a reasonable agreement with the observed fallout depth. Still the extent on the boundary and shape is incorrect. As a preliminary result, the volumetric strain is not found to be a good indicator of fallouts of hard (high strength) rock masses. Also, due to the high rock mass strength, no shear bands were formed when evaluating the maximum shear strain, except when using instantaneous softening of friction and/or cohesion. However the instantaneous softening approaches significantly overestimated the predicted fallouts. Despite the fact that none of the approaches in this study showed perfect agreement with the actual fallouts, a 2D stress analysis program can be used for guidance of where, on the boundary, the actual compressive fallout will occur.

  • 337.
    Edelbro, Catrin
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Prediction of failure and fallouts in access drifts at the Kiirunavaara mine using numerical analysis2008Ingår i: MassMin 2008: Proceedings of the 5th International Conference and Exhibition on Mass Mining, Lulea, Sweden 9-11 June 2008 / [ed] Håkan Schunnesson; Erling Nordlund, Luleå: Luleå tekniska universitet, 2008, s. 835-844Konferensbidrag (Refereegranskat)
  • 338.
    Edelbro, Catrin
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Rock mass strength: a review2003Rapport (Övrigt vetenskapligt)
    Abstract [en]

    The estimation of the rock mass strength is becoming more and more important as the mining depths increase in Swedish mines. A better understanding of the rock mass strength makes it possible to control stability problems in underground excavations. This review constitutes the first phase of a research project aimed at developing a suitable method to estimate the hard rock mass strength. One of the most common ways of determining the rock mass strength is by using a failure criterion. The existing rock mass failure criteria are stress dependent and often include one or several parameters that describe the rock mass properties. These parameters are usually based on classification or characterization systems. This report is a critical literature review on failure criteria for intact rock and rock masses and on classification/characterization systems. Those criteria and systems that are presented were selected based on the facts that they are published, well known, deemed suitable for underground excavations and/or instructive. Totally eleven failure criteria for intact rock, five for rock masses and nineteen classification/characterization systems are presented. To decide which systems and criteria that are applicable for hard rock masses, some limitations have been stated. The rock mass is assumed to be continuous, comprising of predominantly high-strength rock types with a uniaxial compressive strength of the intact rock in excess of 50 MPa and with a failure mechanism caused by compressive stresses. The limitations for further studies of the classification/characterization systems are that they should present a result that is related to the strength, give a numerical value, have been used after the first publication and be applicable to hard rock masses. Based on this study, it was concluded that the uniaxial compressive strength, block size and shape, joint strength and a scale factor are the most important parameters that should be used when estimating the rock mass strength. Based on these findings, selected systems and criteria were chosen for further studies. These include Rock Mass Rating (RMR), Rock Mass Strength (RMS), Mining Rock Mass Rating (MRMR), rock mass quality (Q- systemet), rock mass Number (N), Rock Mass index (RMi), Geological Strength Index (GSI) and Yudhbir, Sheorey and Hoek-Brown criterion.

  • 339.
    Edelbro, Catrin
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Strength, fallouts and numerical modelling of hard rock masses2008Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [sv]

    Att förutsäga och bedöma tryckspänningsinducerade skador och utfall av berg är av stor betydelse för djupt belägna konstruktioner inom både gruv- och tunneldrift. Höga bergspänningar kan leda till utfall av berg, vilket i sin tur är en säkerhetsrisk för de som arbetar under jord samt att maskiner kan skadas och/eller att produktionsstörningar uppstår. Syftet med denna avhandling har varit att studera lämpliga materialmodeller för att kunna bedöma utfall orsakade av höga tryckspänningar. Denna avhandling fokuserar på vanligt förekommande metodiker för design av underjordskonstruktioner med tillämpning på hårda bergmassors. Målet är att föreslå den mest lämpade materialmodellen för att bedöma utfall samt att identifiera de faktorer som är styrande för hårda bergmassors hållfasthet.En omfattande litteraturstudie av existerande klassificeringssystem och brottkriterier för bergmassan har genomförts i detta arbete. För att utvärdera dessa system och kriterier användes tre fallstudier. Ett så kallat "Round Robin Test" utfördes för två av dessa fall. Baserat på fallstudien så bedömdes "rock mass quality" (Q-system), "rock mass Number" (N-system), "Rock Mass index" (RMi), Yudhbir - "Rock Mass Rating" (RMR76) and Hoek-Brown - "Geological Strength Index" (GSI) vara de brottkriterier och system som gav en relativt god överensstämmelse med de spänningar som uppmätts vid brott. De parametrar som återspeglar sprickans skjuvhållfasthet hade störst påverkan på de uppskattade hållfasthetsvärdena. RMi metoden visade sig vara svår att använda. För att bedöma kvaliteten av en bergmassa ansågs ett spänningsreduceringsfritt Q-system (eller N metoden) vara mest lämpligt, då beskrivningen av parametrarna i detta system är bättre och omfattar fler geologiska förhållanden än för RMR-systemet. För massiva bergmassor som är kraftigt sammanpressade av höga spänningar, är påverkan av sprickornas egenskaper av mindre vikt och GSI metoden anses vara lämplig för att bedöma bergmassans kvalitet.För att kunna utvärdera lämplig materialmodell så har resultaten från numeriska analyser jämförts med fältobservationer av skador och utfall. Totalt beskrivs sex fallstudier, hämtade från gruvor och tunnlar, där utfall har skett i hårda bergmassor. Uppmätta spänningar i berget, bergmassans egenskaper och beteende är väl dokumenterade för respektive fall. Dessa fall baseras på en omfattande studie och insamling av välbeskrivna utfall orsakade av höga spänningar i tunnlar och schakt. Fältobservationerna har jämförts med beräknade resultat från numeriska analyser i Finita Element programmet Phase2. Efter att ha tillämpat fallstudier och utvärderat resultat från numeriska analyser ansågs den mest lämpade materialmodellen vara kohesions-mjuknande friktions-hårdnande.Resultaten i denna avhandling visar också hur man kan tolka resultat från numeriska analyser med hänsyn till potentiella brott och utfall då man använder en kohesionsmjuknande friktions-hårdnande materialmodell. Korsande skjuvband med genomgående höga värden, som mynnar ut på randen av utbrytningen samt som finns inom den plasticerade zonen bör tolkas som potentiellt utfall. Skjuvbanden och zonen av plasticerade element var elementberoende. Genom att använda små element (0.01 m) på och nära randen av utbrytningen och i det område där potentiellt utfall var möjligt så innebar fortsatt reducering av elementstorleken inte någon större påverkan på resultatet.Tillämpningen för att förutsäga brott och utfall med hjälp av en kohesions-mjuknande friktions-hårdnande modell utfördes för Kiirunavaaragruvans fältorter i liggväggen. En flerstegsanalys utfördes för att kunna simulera förändringar i spänningar påverkade av gruvbrytningen. En parameterstudie genomfördes där hållfasthetsparametrar, lokalisering av orterna med avseende på avstånd till produktionen samt tvärsnitten på liggväggsorternas varierades. Resultaten påverkades mycket av formen på orten. För fältorter på samma nivå som produktionen fanns en tydlig tendens till tryckspänningsinducerade utfall i anfanget i riktning mot malmen. Lokaliseringen av det beräknade brottet i anfanget var mer tydligt för ett platt tak kontra den teoretiska profilen av tvärsektionen. Resultaten indikerar att den verkliga formen på fältorterna skiljer sig från den teoretiska profilen.Genom att ta bort de element i modellen som motsvarade verkliga utfall visade resultaten från simuleringen att färre utfall av tryckspänningsinducerade utfall kunde förväntade i senare belastningsskeden för Kiirunavaaras fältorter. Genom att skrota bort skadat berg och skapa en v-formad kil i taket (liknande den som förväntas ske vid simuleringen) för en ort i Kristinebergsgruvan kunde stabiliteten förbättras.

  • 340.
    Edelbro, Catrin
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Strength of hard rock masses: a case study2006Rapport (Övrigt vetenskapligt)
    Abstract [en]

    Knowledge of the rock mass strength is important for the design of all types of underground excavations. An improved rock mass strength prediction, as well as a better understanding of the failure process in a rock mass enables e.g., reduced stability problems in underground design and reduced waste rock extraction, improved working conditions underground, and, ultimately, reduced operating costs for underground and mining work. This report constitutes a portion of a PhD project, which was initiated due to the relatively limited knowledge of failure behaviour and the rock mass strength. The aim of the project is to develop a methodology to estimate the strength of hard rock masses. Case histories, where the determined/estimated rock mass strength from a criterion/system can be compared to a measured/determined rock mass strength, are presented in this report. Hence, this report is a summary of all collected field data of observed or documented rock mass failures within this PhD project. For each case presented in this report (except the Stripa case), the following requirements were fulfilled: 1. a rock mass failure has occurred in an underground excavation, with typical tunnel dimensions (approximately 2-10 m), for which the rock mass can be treated as a continuum, 2.the failure is stress induced, for instance spalling, shear failure, slabbing, buckling or compressive failure, 3.stress measurements has been performed (or good knowledge of the in- situ stresses exists), and 4.the uniaxial compressive strength of intact rock (laboratory scale) was above approximately 50 MPa. A total of 14 cases where failure has occurred are presented in this report. First, mining industry cases are presented, comprising three cases from Sweden and one case from Finland. Secondly, two cases of underground storage facilities from Sweden are described. Thirdly, a large scale test from Sweden is presented, and finally, three tunnel cases from Norway are described.

  • 341.
    Edelbro, Catrin
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Tryckspänningsreducerade utfall i bergmassor2009Ingår i: Föredrag vid Bergmekanikdag i Stockholm 9 mars 2009, Stiftelsen bergteknisk forskning - Befo , 2009, s. 57-67Konferensbidrag (Övrigt vetenskapligt)
  • 342.
    Edelbro, Catrin
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Validation of numerical analysis: a feasibility study2012Rapport (Övrigt vetenskapligt)
    Abstract [sv]

    Syftet med denna förstudie var att öka förståelsen för var, vad, när och hur mätningarna bör utföras för att kunna validera numeriska analyser. Detta arbete har fokuserat på validering av befintliga materialmodeller och programvaror som används av LKAB för bergmekaniska analyser. Sekundära spänningar orsakade av gruvdriften, deformationer och plasticering runt fältorter i liggväggen i Kiirunavaara gruva har studerats.Baserat på denna förstudie kan man dra slutsatsen att det är fördelaktigt att utföra mätningar i orter som ligger nära malmkontakten. Bergmassans hållfasthet hade en stor påverkan på resultatet av de beräknade spänningarna, deformationerna och storleken på den plasticerade zonen. Young's modul hade en stor påverkan på deformationerna, särskilt för låga värden på styvheten.Den bästa positionen att mäta spänningar på i fältorter visade sig vara i taket och det är nödvändigt att installera utrustningen i taket när produktionen är (eller öppningen har börjat) två nivåer ovanför den studerade orten. Om spänningarna ska mätas i andra riktningar är det viktigt att installera utrustningen när produktionen ska börja tre nivåer ovanför den studerade orten för att kunna studera alla stora förändringar som sker orsakade av gruvdriften.Det nedre högra hörnet (i motsatt riktning till malmkontakten) är den lämpligaste platsen för övervakning både x-och y-förskjutningen. Utrustningen för att mäta deformationer/förskjutningar bör installeras i den studerade orten när produktionen har påbörjats en till två nivåer ovanför.De bästa positionerna att mäta skadezonen (EDZ) är i väggarna. Hur än om det är spänning, deformation eller EDZ som ska övervakas så behöver installation av sådan utrustning finnas med i gruvkartan redan då orten planeras. Förslaget på framtida arbete är att starta ett valideringsprojekt.

  • 343.
    Edelbro, Catrin
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Nordlund, Erling
    Influence of blast design on rock slope stability2002Ingår i: Proceedings of the ISRM International Symposium on Rock Engineering for Mountainous Regions, EUROCK, 2002Konferensbidrag (Refereegranskat)
  • 344.
    Edelbro, Catrin
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Sandström, Daniel
    Boliden Mineral AB.
    Interpretation of failure and fallouts based on numerical modelling of an underground mine stope2009Ingår i: Proceedings of the ISRM-sponsored International Symposium on Rock Mechanics: "Rock Characterisation, Modelling and Engineering Design Methods" : SINOROCK2009 / [ed] John A. Hudson; George Tham; Xia-Ting Feng; Alan Kwong, Hong Kong: International Society for Rock Mechanics , 2009Konferensbidrag (Refereegranskat)
  • 345.
    Edelbro, Catrin
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Sjöberg, Jonny
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Dahner-Lindqvist, Christina
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Malmgren, Lars
    Prediction and follow-up of failure and fallouts in footwall drifts in the Kiirunavaara mine2012Ingår i: Canadian geotechnical journal (Print), ISSN 0008-3674, E-ISSN 1208-6010, Vol. 49, nr 5, s. 546-559Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A likely result of changes in rock stresses due to progressing mining is an increased number of compressive stress–induced failures. This paper presents the results from numerical analysis and observations of stress-induced fallouts infootwall drifts in the Kiirunavaara underground mine. A brittle-plastic cohesion-softening friction-hardening (CSFH) material model was used for simulating brittle fallouts. To account for mining-induced stress changes, the local model stress boundary conditions were extracted from a global model. The rock mass properties were based on field observations in the footwall drifts as well as on results from laboratory testing. A multi-stage analysis was carried out to gradually change the stresses to simulate mining progress. A parametric study was conducted in which strength properties, location, and shape of the footwall drift were varied. Yielded elements and maximum shear strain were used as damage and fallout indicators. The modelling results were sensitive to the shape of the drift. The location of the predicted fallouts was in good agreement with the location of observed fallouts for the case in which the drift roof was simulated flatter than the theoretical cross section. The results indicate that the true shape of the drift is different from the planned one

  • 346.
    Edelbro, Catrin
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Sjöberg, Jonny
    Nordlund, Erling
    A quantitative comparison of strength criteria for hard rock masses2007Ingår i: Tunnelling and Underground Space Technology, ISSN 0886-7798, E-ISSN 1878-4364, Vol. 22, nr 1, s. 57-68Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Knowledge of the rock mass strength is important for the design of all types of underground excavations. A frequently applied approach for estimation of the rock mass strength is through an empirical failure criterion, often in conjunction with rock mass classification/characterisation systems. This paper presents a review of existing methods to estimate the rock mass strength using empirical failure criteria and classification/characterisation systems—in this study, commonly denoted as estimation methods. A literature review of existing methods is presented, after which a set of methods were selected for further studies. The selected methods were used in three case studies, to investigate their robustness and quantitatively compare the advantages and disadvantages of each method. A Round Robin test was used in two of the cases. The case studies revealed that the N, Yudhbir-RMR76, RMi, Q-, and Hoek–Brown-GSI methods, appeared to yield a reasonable agreement with the measured strengths. These methods are thus considered the best candidates for realistic strength estimation, provided that care is taken when choosing values for each of the included parameters in each method. This study has also clearly shown the limits of presently available strength estimation methods for rock masses and further work is required to develop more precise, practical, and easy-to-use methods for determining the rock mass strength. This should be based on the mechanical behaviour and characteristics of the rock mass, which implies that parameters that consider the strength of intact rock, block size and shape, joint strength, and physical scale, are required.

  • 347.
    Edin, Erik
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Ström, Mattias
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Comparing a full scale test with FDS, FireFOAM, McCaffrey & Eurocode2019Självständigt arbete på grundnivå (yrkesexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

    In the rapidly growing field of CFD-calculations (Computational Fluid Dynamics), companies and organizations are bringing forth new tools, tools that display an image of a given fire scenario. These tools are developed because they provide time efficiency as well as a sustainable economic approach. Another useful tool is analytical solutions, these analytical solutions serve the same purpose as CFD-modeling, providing results of a given scenario. The purpose of this thesis was to simulate a fire plume with two different CFDprograms and compare the gas temperature from each simulation with a full-scale test. Also, analytical solutions were used to perform the same comparisons. Four different calculation models were utilized to obtain results. The CFD-programs were FDS (Fire Dynamics Simulator) and FireFOAM. The analytical solutions were performed using McCaffrey´s plume equation and Eurocode solutions for localized fire temperatures. FDS is a very well documented program, due to this, problems that arose were easily fixed. The structure of FDS enables the user to maneuver the program easily. SmokeView was used to visualize the simulation. FireFOAM is written in C++ and is operated through the command prompt. The structure of the program was time-consuming to understand mainly because of two reasons, primarily because the authors lack of knowledge in coding in C++, and second because of the LINUX environment. Moreover, the process of working in FireFOAM was mostly through trial and error. On some occasions, issues arose that could be solved by communication with other CFD users at CFD-Online. When major problems occurred, regarding the code or other CFD issues, Johan Anderson at RISE Research Institutes of Sweden guided us through most of these problems and enabled us to move forward with the work. ParaView was used to visualize the simulation, and Excel was used to evaluate the temperature data from the FDS- and FireFOAM simulations. For the calculations in FDS and FireFOAM, a sensitivity analysis was performed to see which grid size presented best results in each program. A grid size of 5 cm, 10 cm, and 20 cm were applied in FDS, and in FireFOAM the grid dimensions were set to 5 cm and 10 cm. The results showed that 5 cm was the most appropriate grid size for both programs. It would have been more favorably to simulate with several different grid sizes, to further strengthen the grid analysis. Though, due to the time frame of the thesis, further simulations were not performed. Calculations were repeated for the same scenario only with a lower HRR (Heat release rate). An extensive sensitivity analysis was conducted for FDS in the form of two different simulations. One simulation where HRR was the same as the full-scale test but with twice the area of the burner. In the second simulation, the same area was used on the burner as the fullscale test, but with half the HRR. Results from the analytical solutions were easy to achieve; however, the model has some limitations regarding calculations within the flame region. The estimated gas temperature, using FDS, aligns well with the full-scale test. The temperatures analyzed from FireFOAM deviated in general through the flame region and reached unreasonable high temperatures close to the ceiling. Since the analytical solutions were based on different conditions compared to those applied in the full-scale test, it was expected that the results should deviate. However, McCaffrey plume equations can still be used to give an approximate picture of scenarios similar to that of the full-scale test, and the same applies to Eurocode solutions for localized fire temperatures. Analysis of the results shows that FDS can be used to simulate similar scenarios. FireFOAM simulates a gas temperature that is overestimated within the flame region. One of the reasons for this was due to the grid size since the sensitivity analysis III showed that a refined grid size resulted in more correct temperature value, the reason for not simulating with a more refined grid size was due to the restricted time frame of this thesis. FireFOAM is, at present, recommended for researchers who wish to use the code for specific purposes. Therefore, given the same premises, FireFOAM is not recommended for the standard fire safety analysis.

  • 348.
    Eitzenberger, Andreas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Inventory of geomechanical phenomena related to train-induced vibrations from tunnels2008Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [sv]

    Banverket uppskattar att antalet järnvägstunnlar I tätbebyggt område kommer att öka inom de närmaste 20 åren, dels på grund av att tåg är ett miljövänligt transportsätt samt att marken i tätbebyggda områden är begränsad. Det finns därför ett stort behov av tillförlitliga metoder för att bedöma vilka vibrations- samt stomljudsnivåer som kommer att uppstå i bostäderna längs den planerade järnvägen. För att öka förståelsen har Banverket initierat ett forskningsprojekt där denna avhandling utgör den första delen. I denna avhandling har vågors propagering genom bergmassan studerats. Områden som uppkomsten av vibrationerna, hur människor och byggnader påverkas av vibrationer, nationella samt internationella standarder, samt åtgärder för att minska vibrationer har studerats. Slutligen ges förslag på fortsatt forskning.När vågor propagerar genom ett material dämpas vågen. Dämpningen kan bestå av geometrisk dämpning, energiförluster till materialet, eller reflektion och refraktion vid materialgränser. I en bergmassa som innehåller heterogeniteter i varierande skala orsakas dämpningen av vågorna främst av sprickornas egenskaper. Teoretiska modeller av vågors propagering genom en spricka finns rapporterade i litteraturen . Dessa modeller kan användas för att studera en sprickas inverkan på vågor för olika kombinationer av sprickegenskaper, till exempel sprickstyvhet, impedans eller infallsvinkel. Det finns även teoretiska modeller för att studera parallella sprickors inverkan på vågor. Dämpningen av vågor med låg frekvens är dominerande i bergmassor av låg kvalitet men i princip försumbar i hårt friskt berg. Ökad förekomst av sprickor, förkastningar, och materialgränser ökar dämpningen. Det är dock svårt att studera sådana bergmassor på ett bra sätt med analytiska modeller.En bergmassa innehåller en mängd olika typer av heterogeniteter. Trots detta antas oftast bergmassan vara ett isotropt, elastiskt och homogent material vid analyser av stomljud och vibrationer. Detta gäller både numeriska och empiriska modeller. Det finns således ingen metod som beaktar sprickors egenskaper vid analyser av vibrationer i bergmassor. I den fortsatta forskningen bör man studera möjligheten att kombinera metoder som används för att bestämma materialdämpning med metoderna som används för att bestämma dämpningen för sprickor och materialkontakter. Detta skulle möjliggöra utvecklingen av enkla regler för hur bergmassan ska modelleras vid analyser av stomljud. Därtill bör konceptuella modeller användas för att studera vågors propagering genom material med varierande grad av uppsprickning. Dessa enkla modeller bör sedan jämföras med de teoretiska modellerna. De konceptuella modellerna bör sedan kombineras med studier av något eller några väldokumenterade tunnlar. Utifrån analyserna bör det vara möjligt att skapa enkla regler för hur bergmassan ska modelleras då man studerar stomljud.

  • 349.
    Eitzenberger, Andreas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Train-induced vibrations in tunnels: a review2008Rapport (Övrigt vetenskapligt)
    Abstract [en]

    Banverket is expecting that the number of railway tunnels in densely populated areas will increase over the next 20 years due to the lack of available space on the ground surface. Together with the increased awareness of the residents the need for good prediction of vibration and noise levels in dwellings along the planned tunnels is evident. Consequently, a study of the propagation of vibrations through rock and soil generated by trains operating in tunnels is required in order to make more reliable prognoses. This report constitutes the first stage within a research project aimed at increasing the understanding about ground-borne noise and ground-borne vibrations generated by trains moving in tunnels constructed in rock. In this report, the propagation of vibration through a rock mass is reviewed. The emphasis has been on wave propagation in hard rock, but soil has also been included. Areas, such as the generation of vibration at the train-rail interaction, the response of buildings and humans, national and international recommended noise and vibrations levels, measurement of noise and vibrations, and possible countermeasures are briefly reviewed as well. Finally, suggestions for the continued research within this field are presented. The propagation of waves is influenced by attenuation along the propagation path. The attenuation can either be through geometric spreading, energy loss within the material, or reflection and refraction at boundaries. In a rock mass, where heterogeneities of various scales are present, the attenuation of (train-induced) waves through the ground therefore mainly depends on discontinuities, e.g. joints, faults, cracks, crushed zones, dykes, and boundaries between different rock types or soil. Also the topography - along as well as intersecting tunnels - influences the wave propagation in form of local amplification. An increased amount of joints, faults and boundaries increases the attenuation of the waves. The rock mass is in most cases inhomogeneous due to all heterogeneities present. Despite this fact, the rock mass and soil is always treated as an isotropic, homogeneous material when analyzed with regard to ground-borne noise and ground-borne vibrations. This concerns both numerical and empirical methods. Thus, there is a lack of knowledge regarding the influence of various heterogeneities on the propagation of waves, and thereby vibrations, in non-isotropic ground conditions (e.g. a rock mass) at low frequencies. Future research regarding train-induced vibration should focus on conceptual models used to determine the propagation of low-frequency waves in a rock mass containing various amount of heterogeneities (from isotropic to highly inhomogeneous). Once the behaviour of waves in an inhomogeneous rock mass has been established, conceptual models should be used together with measurements from a few well documented cases. From the results of the analysis, guidelines for analysis of railway tunnels with regard to ground-borne noise and ground-borne vibrations should be established.

  • 350.
    Eitzenberger, Andreas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Vågutbredning i berg2013Ingår i: Föredrag vid Bergmekanikdag i Stockholm, 11 mars 2013, Stockholm: Stiftelsen bergteknisk forskning - Befo , 2013, s. 115-126Konferensbidrag (Övrigt vetenskapligt)
    Abstract [sv]

    I tätbefolkade områden kan vibrationer genererade av tågtrafik i tunnlar nå närliggande byggnader i form av stomljud och/eller vibrationer. Tillförlitliga prognoser för att säkerställa att de som vistas i byggnaderna inte ska störas är nödvändigt när man planerar en ny järnväg eller bygger nya byggnader längs en befintlig järnväg. Numeriska analyser är idag en naturlig del vid prognostisering av tåginducerade vibrationer/stomljud. Vid analyserna antas ofta marken bestå av ett homogent och isotropt material. Vågutbredning genom diskontinuerliga bergmassor har studerats med hjälp numeriska analyser för att bedöma om ett sådant antagande är rimligt. Resultaten visar att sprickor under vissa förutsättningar påverkar vibrationerna lokalt på markytan ovanför en tunnel utsatt för en dynamisk last. Egenskaper som har stor inverkan på vågutbredning är sprickans normal och skjuvstyvhet, sprickors orientering och antal samt sprickavståndet. Zoner kan kanalisera vågor vilket resulterar i ökade vibrationer på markytan där zonen når markytan, men kan också agera som en vågfälla eller ett filter. Om det översta skicket av bergmassan har egenskaper som skiljer sig från den omgivande bergmassan förstärks generellt vibrationerna på markytan, särskilt i horisontell riktning.

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