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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Thermal properties of bentonite based barriers : theoretical considerations and laboratory tests with special reference to the Buffer Mass Test in Stripa mine

Knutsson, Sven January 1985 (has links)
No description available.
22

Environmental Perspectives on Urban Material Stocks used in Construction : Granular Materials / Miljöperspektiv på upplagrade material i tätorter och användning i anläggningsarbete : Granulära material

Magnusson, Simon January 2016 (has links)
The peoples demand of functions and services in cities is the driver for energy and material flows. Most people in the world are now living in urban areas. In order to achieve a sustainable development of cities, both resource use and environmental impact have to be reduced. For construction activities, an important aspect is to increase the reuse of construction materials. From a resource perspective, the urban demand for construction of buildings, infrastructure and other facilities results in materials accumulated in constructions but also in other applications and in landfills. The materials can be described as the urban material stock where some materials are used and others are not used, i.e. wasted. There are many cases where material stocks are used for construction purposes. For example, used concrete and bricks, excavated soil and rock from construction projects and other wasted materials such as rubber from tires can be crushed, shredded and sorted to granules and used in many different construction applications. Different perspectives can be applied when assessing the environmental impacts of using stocked material in construction. The overall aim of this thesis is to study the environmental impacts of using granular soil, rock and rubber in construction. For soil and rock, the aim is to study the environmental impact of material management in urban areas. For granular rubber, the aim is to study the environmental impact of artificial turf from a life cycle perspective and from different infill materials of recycled and new rubber and plastics.  The literature of excavated soil and rock was reviewed in order to identify and quantify the material flows and greenhouse gas (GHG) emissions from the management of soil and rock materials. For artificial turf and the different infill materials, a life cycle approach was used to quantify the energy use and GHG emissions. A chemical analysis of potential chemical leaching from the different infill materials to water was conducted in order to compare potential local emissions to water.  Based on the results, it was concluded that the knowledge about the urban flows of excavated soil and rock is lacking in terms of patterns, quantities, qualities and its environmental performance. A resource perspective is missing in the literature. However, the recycling of soil and rock can reduce resource use and GHG emissions. It was suggested that models are developed that take into account future material demand and availability to soils and rock. From such information it would be able to assess sustainable management practices and the possibilities of sharing materials between urban construction projects in order to reduce resource use and environmental impact.  It was concluded that for the life cycle of artificial turf, the production of construction materials contributes largely to energy use and GHG emissions. Differences in terms of energy use and GHG emissions for the production of infill materials are large. The production of new material required more energy and resulted in more GHG emissions than using recycled rubber. The potential release of substances from infill materials to water were shown to be possible for all infill materials analyzed. Previous assessments of local environmental impacts of using infills generally concludes that the impacts are small. These assessments are primarily focused on infill of recycled tires. It is therefore concluded that environmental assessments of local impact should include all infill types.  Environmental assessments of using stocked materials in construction should take into consideration the material applications´ significance for the environmental impacts at a higher system level. Broader system boundaries in environmental assessments will reduce the risk for sub-optimizations when taking decisions on how materials should be used in construction.
23

An Experimental Study to Measure Grout Penetrability, Improve the Grout Spread, and Evaluate the Real Time Grouting Control Theory

Nejad Ghafar, Ali January 2017 (has links)
Due to the significant influence of the grout penetrability properties on spread of grout in rock fractures, this study aimed to investigate the grout penetrability from four different aspects. In Part (a), after review of all the existing methodologies developed to measure the grout penetrability, Filter-pump and Penetrability-meter were examined against Short-slot to figure out which one is more reliable. The study decisively considered Short-slot more reliable. In part (b), the so-called varying aperture long slot (VALS), an artificial fracture with apertures of 230-10 μm, was developed to study the gout penetrability more realistically. In part (c), a low-frequency rectangular pressure impulse was introduced to improve the grout spread by successive erosion of the produced filter cakes in consecutive cycles. The results showed considerable improvement in experiments using Short-slot. The dissipation of the pressure impulses was then investigated using VALS with noticeable remaining amplitudes after 2.0-2.7 m. In part (d), VALS was once more introduced to examine RTGC theory in a fracture with variable aperture. The study showed a relatively satisfactory agreement between the experimental results and the predictions of the grout propagation using the hydraulic aperture, whereas the predictions using the mean physical aperture showed considerably faster spread. / För att uppnå den täthet som krävs i undermarkskonstruktioner är det nödvändigt att uppnå tillräcklig spridning av bruket vid injekteringen. Cementbaserade injekteringsmedel är vanligast inom injekteringsindustrin, eftersom det har flera fördelar, särskilt från ekonomisk och miljömässig synvinkel. Eftersom inträngningsförmågan kan påverkas betydligt hos injekteringsmedel beroende på vilket bruk man använder, är syftet med denna avhandling att studera: a) Vilka av de befintliga metoder som har utvecklats för att mäta inträngningsförmågan hos injekteringsmedel är tillförlitliga? b) Hur kan man mäta inträngningsförmågan hos injekteringsmedel mer realistiskt? c) Hur kan man förbättra spridningen hos injekteringsmedel med hjälp av dynamiska tryckimpulser? och d) Kan Real Time Grouting Control (RTGC)-teorin användas för att förutse spridningen hos injekteringsmedel i en artificiell spricka med varierande vidd? I del a) av studien genomfördes en undersökning av alla befintliga metoder som har utvecklats för att mäta inträngningsförmågan hos injekteringsmedel. Därefter genomfördes en jämförelse mellan Filterpumpen, Filterpressen (d.v.s. två av de vanligaste metoderna i svensk injekteringsindustri) och metoden Kort spalt under så lika provförhållanden som möjligt. Studien visade att Kort spalt är tillförlitligare på grund av dess mer realistiska provförhållanden (d.v.s. geometrin, trycket och injekteringsvolymen) och är därmed en bättre utvärderingsmetod. I del b) utvecklades en så kallad Varying Aperture Long Slot (VALS), en fyra meter lång artificiell spricka med minskande spaltvidder (från 230 till 10 μm), som är en mer realistisk metod för att studera inträngningsförmågan hos injekteringsmedel under statiska/dynamiska tryckförhållanden upp till 20 bar. I del c) användes en lågfrekvent rektangulär tryckimpuls för att förbättra spridningen hos injekteringsmedlet genom successiv erosion av filterkakor som har byggts vid förträngningar i konsekutiva cykler. Resultaten visade en förbättring på upp till 11 gånger mer volym i mätningar med Kort spalt med 30-43 μm breda spaltvidder. Sedan, spridningen av tryckimpulserna undersöktes längs VALS. Resultaten visade att de återstående amplituderna av tryckimpulser kan vara så stora som 46% respektive 25% av den applicerade amplituden 2,0 m respektive 2,7 m in i sprickan. I del d) användes VALS igen för att undersöka om RTGC-teorin kan användas för att bedöma spridningen av injekteringsmedel i en konstgjord spricka med variabel spaltvidd. Studien visade en förhållandevis tillfredsställande överensstämmelse mellan försöksresultaten och förutsägelserna av spridningen hos injekteringsmedel när man tog hänsyn till den hydrauliska öppningen. Som jämföreslse gav förutsägelserna baserade på den genomsnittliga fysiska öppningen (felaktigt) en betydligt snabbare spridning. Detta visar att användning av den genomsnittliga fysiska öppningen inte alltid är lämpligt vid tillämpning av RTGC-teori. Beroende på de geometriska förhållandena kan den hydrauliska öppningen ge en mer realistisk förutsägelse av spridningen hos injekteringsmedlet. / <p>QC 20171121</p>
24

Rain Water Harvesting (RWH) North of Iraq

Zakaria, Saleh January 2014 (has links)
Rainwater harvesting is one of the methods that can ensure availability of water for winter crop in Iraq. Using this technique the excess rainwater (runoff) is stored in reservoirs of dams of different sizes. The water from these reservoirs can be used later when required to satisfy the crops requirements. It is believed that rainwater harvesting will be one of the solutions to overcome water shortages problem in Iraq.This work includes four parts dealing with macro rainwater harvesting modeling. The study area includes selected sites at three Governorates located north of Iraq (Erbil, Sulaymaniyah, and Nineveh). In part one of the work, three selected sites at south, north and east of Sinjar district (Nineveh Governorate) were used. The slope of the study area at Sinjar district is less than 5%. The technique was first applied on southern Sinjar Mountain. Linear programming technique was adopted to optimize the irrigated area of barley crop for irrigation scenario of supplemental irrigation (SI) 100% of full irrigation requirements. Two scenarios of reservoir operation were considered for each main basin. In the first, each reservoir was operated as a separate unit while in the second all reservoirs in main basin were operated as one system. Both scenarios gave encouraging results. Scenario two however, was relatively better. The technique was applied again on the northern and eastern Sinjar Mountain area but with different catchments area and scenarios of irrigation (supplemental irrigation (SI) 100%, deficit irrigation (DI) 50%, and deficit irrigation (DI) 25% of full irrigation requirements). Wheat crop was considered as the main crop grown in the area. A linear programming technique was adopted to optimize the irrigated area for the above three scenarios of irrigation. The results of the three scenarios used indicated that, using deficit irrigation (DI) of 50% can be more beneficial than SI of 100% and DI of 25% of full irrigation requirements. Part two of the work includes application of Macro RWH technique at mountain areas in Northeastern part of Iraq. In these areas, all selected basins having slope more than 5 % and located at the rain-fed farms of Kurdistan region of Iraq, Erbil and Sulaymaniyah Governorates. The annual rainfall is greater than what was available at Nineveh Governorate. Part three of the work focused about the ability of Macro RWH technique to support wheat crop yield production in dry rain-fed farms at north Sinjar district, north west of Iraq, using wheat crop yield-water relationship that conducted by International Center for Agricultural Research in the Dry Areas (ICARDA). Three scenarios of supplemental irrigation (100%, 75% and 50%) of full irrigation. requirements with, various rainfall conditions were used, two types of wheat (bread and durum) were considered. Part four of the work focused on climatic change and future prospects for Macro RWH technique. Box-Jenkins methodology for time series analysis and forecasting (ARIMA model) was used to study future rainfall for 4 main rainfall stations surrounding Sinjar area in order to forecast expected rainfall for the period 2012-2016. Future rainfall depths were forecasted with adoption of a confidence level of 95%. The future rainfall was employed for RWH technique. This part also includes a review of the impact of climatic change on countries of the Middle East and North Africa (MENA region). The climatic model CGCM3.1 (T47) 2 was used to explain the changes in the average temperatures and rainfall on MENA region with special emphases on Iraq. Long term future seasonal rainfall during the period 2020-2099 at east Sinjar (Nineveh Governorate) showed a clear negative trend reflecting the reduction in total seasonal rainfall amount. For these future rainfall depths, the maximum, minimum and average harvested runoff volumes were estimated. The comparison of the runoff results between future and historical recorded rainfall for the same study area was carried out to show the future validity of rainwater harvesting. In order to estimate the amount of runoff that can be harvested from a given catchment area at eastern Sinjar, an attempt was made to provide set of charts that are easy to be used in order to estimate the equivalent harvested runoff depth (mm) for different selected rainfall depths under different hydraulic conditions for the catchment area. Macro rainwater harvesting (RWH) technique had been tested for future rainfall data that predicted by two emission scenarios of climatic change (A2 and B2) for the period 2020-2099 at Nineveh and Sulaymaniyah Governorates north of Iraq. The results of the four parts of the thesis reflect useful values for RWH and its influence to increase the irrigated area and then the crop yield in the studied region when combined with an effective system like supplemental irrigation. Rain-fed land in the studied areas requires effective technique in terms of saving significant runoff water for irrigation purposes and this might be achieved by rain-water harvesting (RWH) technique. / Godkänd; 2014; 20140310 (andbra); Nedanstående person kommer att disputera för avläggande av teknologie doktorsexamen. Namn: Saleh Mohammed Saleh Zakaria Ämne: Geoteknik/Soil Mechanics and Foundation Engineering Avhandling: Rain Water Harvesting (RWH) North of Iraq Opponent: Professor Ahmed Hachum, Dams and Water Resources Engineering Department, College of Engineering, Mosul University, Mosul, Iraq Ordförande: Professor Sven Knutsson, Avd för geoteknik, Institutionen för samhällsbyggnad och naturresurser, Luleå tekniska universitet Tid: Tisdag den 29 april 2014, kl 10.00 Plats: F1031, Luleå tekniska universitet
25

Performance of Clay Liners in Near-Surface Repositories in Desert Climate

Al-Taie, Laith January 2014 (has links)
Wars in Iraq (1991 and 2003) generated various types of hazardous waste (HW) in the form of soil contaminated by depleted uranium (DU). Other HW emanated from destroyed army vehicles and remnants of Iraqi nuclear facilities holding various types and amounts of chemical and radioactive material. The negative impact of the various wastes on the health conditions of the population was reported from different parts of Iraq, showing an enhanced frequency of cancer and abnormally born infants. For isolating the wastes, which represent low-level and short-lived intermediate level radioactive wastes, near-surface repositories (NSR) are proposed since they represent the least expensive way of solving future problems with sufficient safety. Internationally, the timeframe of the containment of such wastes is designated to be 300 years. Site selection affects and largely controls the selection of a suitable design the aim being to minimize or eliminate migration of hazardous elements from the waste to the environment. The formulation of siting criteria is the first vital step toward the resolution of the problem. Site selection criteria are proposed taking in account three major factors: environmental, geological and socio-economic factors. Accordingly, Iraqi deserts, which make up 60% of Iraq, represent the number one candidate for locating a safe disposal facility, primarily because of the low population, suitable topography, climatic conditions, seismic stability and availability of raw materials. Long-term performance of NSR is directly related to the function of top and bottom liner systems. They should be designed so that they are mutually compatible and combine to effectively isolate the waste. Liners are considered as the main elements of any disposal facility on the ground surface and a properly designed top liner system is of particular importance since it will minimize or eliminate water percolation into the waste body. Compacted clay liners (CCL) should preferably have with a low hydraulic conductivity, which is achievable by proper selection of raw materials, compaction density and construction methods. A further criterion is that they must not soften significantly by expansion on wetting, which puts a limit to the smectite content and density. The liners can consist of native material found near the landfill site, and be used after simple processing, primarily drying and crushing, or be mixed with fillers like silty sand. Since the hydraulic conductivity is the key property of a reliable CCL, relevant experimental determination of the hydraulic conductivity is vital. The common practice in geotechnical laboratories is to apply high hydraulic gradients for getting results quickly but this can lead to non-conservative, incorrect results. The present study involved determination of the hydraulic conductivity of a smectite-rich clay sampled at places within reasonable distance from potential NSR sites. Various hydraulic gradients were applied to samples compacted to several different densities, using two permeants and two filter types. It was concluded that the outflow filter can significantly affect the evaluated conductivity especially when applying high hydraulic gradients. This was partly explained by clogging of outflow filters of conventional fine-porous type by torn-off clay particles at such gradients. A major conclusion was that the gradient in laboratory testing should not exceed 100 m/m.In order to assess the suitability of available raw materials within the Iraqi Deserts, two smectitic soils termed as Green and Red clays were investigated for potential use in CCLs. Both clays are fairly rich in smectite, which calls for mixing them with properly graded silt/sand material from the desert for modifying the expandability. The shear strength, swelling pressure, hydraulic conductivity and creep properties were determined and used for defining criteria for selecting suitable clay-sand ratios. The results showed that 30-50% Green clay mixed with sand and 40-60% Red clay mixed with sand were suitable for constructing top liners with a hydraulic conductivity of 1×10-9 - 1×10-10 m/s. For bottom liners, 70% Green clay mixed with sand and 80% Red clay mixed with sand would be suitable; they were found to have a hydraulic conductivity of 1×10-11 m/s.The long-term performance of CCL is controlled by a number of processes like long periods of extreme dryness and short periods of very heavy rain. The percolation of water through the top liner system of a number of design alternatives were simulated using the code HELP 3.95D and subsequently by the FE program VADOSE/W. For the assumed NSR concept the slope stability of the top liner is essential and it was determined by using FE technique considering various slope angles. The engineering properties, primarily the hydraulic conductivity, swelling pressure and shear strength of 30-50% Green clay mixed with sand were introduced in the simulations. Two initial water contents of the compacted materials were considered representing 1) optimum water content (“wet case”), and 2) air‐dry conditions (“dry case”). Application of the HELP code decided the selection of suitable CCL having a thickness of 0.5 m and inclined by 5.7ᵒ. More detailed analyses with VADOSE/W showed that a mixture at the dry case would bring 0.5 mm (0.5 litre of leaking water per square meter) through CCL in an eight year simulation period. Long-term simulations (up to 300 years) showed that CCL would undergo continuous drying without reaching saturation even in the case of periods of very heavy rain (616 mm) for the wet and dry cases. The slope stability factor for the rather steep angle 30ᵒ was found to be 1.5 for the most critical case representing complete water saturation. In conclusion, the proposed materials and design features are believed to be suitable for practical application. / Godkänd; 2014; 20140924 (laikha); Nedanstående person kommer att disputera för avläggande av teknologie doktorsexamen. Namn: Laith Al-Taie Ämne: Geoteknik/Soil Mechanics and Foundation Engineering Avhandling: Performance of Clay Liners in Near-Surface Repositories in Desert Climate Opponent: Professor Frank Wagner, University of Trier, Department of Geology, Tyskland Ordförande: Professor Sven Knutsson, Avd för geoteknologi, Institutionen för samhällsbyggnad och naturresurser, Luleå tekniska universitet Tid: Onsdag den 3 december 2014, kl 13.00s Plats: F1031, Luleå tekniska universitet
26

Sulfidjordars kompressionsegenskaper : Inverkan av tid och temperatur : en laboratoriestudie

Eriksson, Lars G. January 1992 (has links)
No description available.
27

Planeringshjälpmedel för ökad tillgänglighet på grusvägnätet : en studie av datorverktyget HDM-4

Johansson, Karin January 2005 (has links)
I dagsläget saknas i Sverige ett verktyg som behandlar både belagda och icke-belagda vägar i arbetet med långtidsplanering av vägnätet. För att kunna göra en riktig fördelning av resurser för drift- och underhållsåtgärder över vägnätet krävs ett verktyg som kan behandla samtliga vägtyper och som ger jämförbara resultat. Genom att använda programmet "Highway Development and Management systems", HDM-4, är det möjligt att simulera nedbrytning och åtgärdseffekter för det totala vägnätet, som en enhet. Målet med detta är att kunna simulera vägars tillståndsutveckling och lönsamhet vid olika underhållsstrategier, oavsett beläggningstyp. Kan detta uppnås är förhoppningen att man utifrån en begränsad budget kan utföra det lämpligaste underhållet för att öka standarden på vägnätet. Det faktum att grusvägsmodulen i HDM-4 inte nyttjas i områden med kallt klimat, samt att nedbrytnings- och åtgärdsmodellerna är utvecklade utifrån studier gjorda i områden med totalt annat klimat än Sverige gör att dessa bör valideras innan programmet tas i bruk. Syftet med detta arbete är att genom simuleringar av tillståndsutvecklingen för ett antal grusvägar visa på brister, användningsområden och möjliga idéer till förbättringar av HDM-4. Studier av nedbrytnings- och åtgärdsmodellerna visar på brister i främst anpassningen av modellerna till vinterklimat. I simuleringar med HDM-4 antas ojämnhetsutveckling och materialförlusten från en grusväg vara lika stor över hela året. Detta kan vara rimligt i områden där vägarna inte är snötäckta och frusna stora delar av året. Detta är dock fallet i norra Sverige. Det faktum att nedbrytningen av en väg inte sker på samma sätt under vinterhalvåret som under barmarksperioden tas det heller ingen hänsyn till i modellerna. Simuleringarna visar på möjligheter att använda HDM-4 för att se trender i ojämnhetsutveckling och materialtransport för olika åtgärdsstrategier. De faktorer i modellerna som tar hänsyn till klimat går inte enkelt att anpassa till nordiska förhållanden. Detta medför att tillförlitligheten av de numeriska värdena från simuleringarna bör behandlas med försiktighet när programmet används. Försök med att endast simulera barmarksperioden har även utförts. Dessa visar på en möjlig lösning till att enbart simulera nedbrytningen och effekterna av åtgärder under barmarksperioden. Utifrån de studier av programmet som hittills har utförts finns en möjlighet att kunna använda programmet för prioritering av insatser för det svenska grusvägnätet på en översiktlig nivå. Detta utan att ändra i de ekvationer som ligger till grund för nedbrytningsmodellerna. Programmet är däremot för grovt för att använda vid studier av enstaka objekt i detalj. De variationer i IRI som återspeglar olika nivåer av åtgärder kan tydligt identifieras, vilket innebär att programmet kan användas för att urskilja trender i ojämnhetsutvecklingen för olika åtgärdsalternativ. Ytterligare studier bör utföras för att testa de idéer till ändringar som hittills kommit fram i projektet. / Godkänd; 2005; 20061218 (haneit)
28

Risken för utfällning av ferriföreningar ur dräneringsvatten från anaeroba och aeroba sulfidjordar

Mácsik, Josef January 1994 (has links)
<p>Godkänd; 1994; 20080401 (ysko)</p>
29

Uppmätta och beräknade tjällyftningar och tjäldjup i jord : en analys av ingångsparametrarnas betydelse för beräkningsresultatet

Vikström, Lars January 1999 (has links)
Målet med arbetet som ligger till grund för licentiatuppsatsen har varit att bestämma behovet av och omfattningen på fält- och laboratorieundersökningar för att erhålla tillförlitliga resultat från beräkningar med programmet Pc-heave. Utgångspunkten har varit att studera om man enbart med en enklare fält- och laboratorieundersökningar kan erhålla ingångsparametrar som ger tillräcklig noggrannhet vid predikteringen av tjällyftning och tjälnedträngning i en jord med hjälp av programmet Pc-heave. Syftet har varit att beräkningen skall vara en prognos och utföras utan att i efterhand behöva anpassa parametrarna för att uppnå överensstämmelse mellan beräknade och uppmätta värden på tjälnedträngning och tjällyftning. Med anpassning av sådana parametrar som, mängd ofruset vatten och permeabilitet, utifrån en kortare tids, en månads, observationer i inledningen av tjälningsperioden erhåller man god överensstämmelse mellan beräknade och uppmätta värden på tjällyftning, islinsernas läge och mäktighet och tjälnedträngningen. Islinsernas läge och mäktighet i den frusna jorden har detekterats med hjälp av röntgenfotografering av upptagna borrkärnor. Ingångsparametrar valda utifrån enklare undersökningar av typen kornfördelning, densitet, vattenkvot eller ytterligare parametrar bland annat ofrusetvatteninnehåll och permeabilitet bestämda i laboratorium ger däremot sämre resultat. / <p>Godkänd; 1999; 20070320 (ysko)</p>
30

Stability of tailings dams : focus on water cover closure

Bjelkevik, Annika January 2005 (has links)
Mining activities have been ongoing for thousands of years within Sweden. As the results of previous activities are evident today, i.e. for example acid mine drainage (AMD), the focus and interest on closure and remediation of mine sites and tailings storage facilities (TSFs) has increased. At present all mines in operation have closure plans according to legal requirements. The purpose of a closure plan is to make sure that the site is safe when the mine comes to an end and the mining company abandons the site. The need for remediation of TSFs, where the fine (crushed and milled) waste material, i.e. tailings, from the process plant is stored, is important with regard to the consequences for the future environment. The composition of the tailings vary, i.e. content of chemicals, minerals etc., from mine site to mine site. Unwanted processes taking place in the tailings within the TSF may result in acidic leachate and leaching of metals and heavy metals from the TSF. These processes will be harmful for the environment and must therefore be prevented or reduced to levels that the environment can handle. They need to be controlled through a proper remediation and closure design of the facility. One method to control these processes is by covering the impoundment with water. One of the most important requirements when using this method is the stability of the tailings dams surrounding the impoundment. Without stable tailing dams the water cover will not stay. Long term stability of tailings dams has been the focus of this research project. Long term has in this case been set to 1000 years or more, which has become an international praxis in the last couple of years. To understand what we need to know in order to achieve long term stable tailings dams several areas have been studied. One idea used, was that we need to know, and understand, how tailings dams in operation perform today in order to understand how they may perform in a long term perspective. This resulted in studies of tailings dam safety in Sweden (see Benckert , 2003 and 2004) and of incidents and failures at Swedish tailings dams (see Bjelkevik, 2005b and 2005c). Another field of importance is the properties of tailings and for dam stability purposes the mechanical properties of tailings as a construction material. Sampling and laboratory tests where performed in 2002/2003 in order to compare the properties of tailings with natural materials (see Bjelkevik and Knutsson, 2005a). The conclusion drawn is that tailings have different properties compared to natural materials and the way of testing tailings material need to be calibrated for these differences. It was also concluded that this is a field requiring much more attention in the future. The focus of this thesis has been the long term dam stability and the factors and processes affecting this. In the State of the Art report (Bjelkevik, 2005d) this is covered and discussed. The most important factors for long term dam stability are: the hydraulic gradient and its relation to internal erosion extreme events like floods, drought, high winds, earthquakes etc. slow deterioration processes like erosion, weathering, frost and ice forces etc. These aspects have been analysed and discussed within the thesis. One valuable source for improving our knowledge on long term stability is natural analogies that have been stable since the last glacial period. Another valuable source is ancient structures, like man made earthen mounds and dams. Existing knowledge of some of these types of structures are presented in the thesis. The author, however, believes that there are a lot more information and knowledge to gain from analysis of these types of structures. Finally, the conclusions from this research project are: no Swedish tailings dams can be regarded as long term stable today it is possible to design long term stable tailings dams more knowledge can be gained from natural analogies and ancient structures the most challenging aspects in designing long term stable tailings dams are probably not the technical aspects, but the non-technical In order to be able to define criteria for long term stable tailings dams several areas need further attention and research. Examples of these areas are: internal erosion long term changes in material properties the effect of the hydraulic gradient on slope stability interaction between tailings material and sealing elements/foundation within the tailings dam external erosion seepage points / <p>Godkänd; 2005; 20061213 (haneit)</p>

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