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

No description available.

No description available.

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)

<p>Godkänd; 1994; 20080401 (ysko)</p>

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>

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>

Vid gruvbrytning genereras bland annat ett finmalet gråbergsavfall, anrikningssand. Den vanligaste deponeringsmetoden för anrikningssand är att den tillsammans med vatten pumpas eller leds till en gruvdamm. Där deponeras anrikningssanden genom sedimentation. Trots att det är den vanligaste deponeringsmetoden är den behäftad med svagheter. Det uppdämda vattnet i gruvdammen kan ge upphov till incidenter och i olyckliga fall till allvarliga haverier. Ett sätt att minska riskerna och att öka stabiliteten, är att deponeringen sker under dränerade förhållanden. Detta kan åstadkommas med hjälp av sildammar. För att studera funktion och lämplig uppbyggnad av sildammar har ett anta fält- och laboratorieförsök genomförts. Grovkornigt gråbergsavfall, kallat sovringsgråberg, användes när sildammarna byggdes. Sildammarnas uppgift var att hindra flödet av anrikningssand genom filtrering och samtidigt tillåta dränering av inpumpat vatten. Syftet med denna licentiatuppsats har varit att hitta en lämplig design för sildammar. Efter en inledande litteraturstudie byggdes testanläggningar, både som rännförsök och i pilotskala. I testanläggningarna testades olika sildammar genom att dess filtrerande och dränerande förmåga undersöktes. Testerna föregicks av laboratorieförsök där sildammsmaterialens hydrauliska konduktivitet undersöktes. Testerna visar att vid valet av lämpligt material för sildammar, kan filterkriteria användas tillsammans med bedömningar av materialets hydrauliska konduktivitet. Finns inte lämpligt sovringsgråberg att tillgå, kan geotextiler användas som filter i en sildamm. Sildammarnas filtrerande förmåga beräknades som verkningsgrader, vilka låg mellan 34 - 100 % beroende på sildammarnas design. Sildammarnas dränerande förmåga beräknades i det deponerade materialet med hjälp av uppmätta och beräknade porvattentryck. Porvattentrycken sjönk mellan 60 - 100 % under testperioden. Testerna visar att det deponerade materialets egenskaper påverkas av den inpumpade mängden av vatten och anrikningssand samt av sildammarnas funktion. Där sildammens filtrerande förmåga var hög, tog det längre tid innan det deponerade materialet dränerades. Vidare påverkas sildammarnas funktion av det deponerade materialets egenskaper. Vid deponeringen skedde en partikelsegregering, då de tyngsta partiklarna sedimenterade närmast inloppsröret medan lättare partiklar transporterades längre innan de sedimenterade. Denna segregation påverkar sildammens dränerande funktion negativt. Sildammen kan inte filtrera enbart de finkornigaste partiklarna samtidigt som sildammen skall dränera det inpumpade vattnet. Ju mer omfattande partikelsegregationen är och ju bättre sildammen kan hindra de finkornigaste partiklarna, desto större kommer sättningarna i det sedimenterade materialet bli nära sildammen. Detta kan försvåra dränering av ytvattnet. Testerna genomfördes sommartid. Framtida undersökningar bör koncentreras på att anpassa metoden även för vinterförhållanden. Vidare bör materialprover tas för att få en bättre uppskattning av partikelsegregationen. Målet är att kunna beräkna deponins optimala storlek. Slutligen bör ytterligare fältförsök genomföras där anrikningssanden deponeras i våningar. Vid dessa försök bör det deponerade materialets dräneringsförmåga ytterligare utredas tillsammans med undersökningar av eventuella erosionsproblem i underliggande sildammar från dränerat vattnet. / Godkänd; 2005; 20061215 (haneit)

Tunnels have been built since 2180 B.C., through the stone age. They became popular worldwide since the eighteenth century, as transportation, military, mining, conveyance, storage and flood control structures. Due to the increasing world population, urbanization and industrialization, the construction of underground tunnel structures are preferred as they limit interferences with existing surface uses of the land and water bodies. Although underground tunnels are a common flexible construction alternative, they are high hazard risk structures. The risks are mostly related to ground conditions. Tunnels buried at depth disturb in-situ conditions, cause ground instability and ultimately failure. Widespread tunnel failures, though not publicly advertised because of their adverse implications, have claimed human lives, cleared cities, cost 100 million United States dollars' worth in financial losses and year-long project delays. As such, stability of the structures is crucial to prevent the catastrophes thereby reducing societal outcries. Permanency of underground structures is ensured by provision of adequate resistance to any impeding failure of the ground surrounding deep underground excavations. The effectiveness of the ground-support interaction depends on geology, material properties, geotechnical parameters, loads of the surrounding ground mass and mechanism of the interaction. Using actual project information, the factors influencing stability, structural resistance as well as methods to select the required support are explored in this dissertation. The study used typical geological data of an underground tunnel component of Karuma, a proposed 600MW hydropower project in Uganda. It doubles as the largest hydropower project and first underground construction, to date. The project is located along the River Nile in a sensitive ecosystem neighboring both a major national park and the Great Rift Valley system in East Africa. The instability problem at Karuma was assessed using scientific and universal tunneling practice. Typical site data formed input for the geotechnical engineering design of the tunnel support based on analytical, observational and empirical methods. The study demonstrated that all methods were independent and dissimilar for the same geotechnical engineering challenge of the underground structure. The most comprehensive method was the one based on geotechnical engineering principles and rock mechanics theory. The outcomes of the different approaches in this study were unique functions of their underlying scientific philosophies. The study proposes that in designing adequate support systems to resist forces causing failure of underground tunnels, excavations buried in the ground should encompass several methods. The most conservative design should be chosen to ensure permanency.

Densification of soil during construction of earth structures is achieved through the process of compaction by application of mechanical energy to obtain the required engineering properties of the soil for a particular project such as hydraulic conductivity, soil strength and compressibility. These properties are dependent on attainment of high compaction densities normally achieved at specific moisture contents for a given compactive effort. The optimum moisture content and maximum dry density for a particular soil is determined by means of Proctor tests in the laboratory. A relative compaction index is then used to correlate the laboratory values with the field compaction values obtained using in-situ tests. The Sand Cone (SC) and Nuclear Density Gauge (NDG) are the common field tests used to the dry density and moisture content of the soil for purposes of quality control of the compaction process. The sand cone is a laborious test that involves excavation of part of the compacted layer and requires a 24-hour waiting period to obtain the moisture content of the soil through the laboratory oven method. The NDG on the other hand is less laborious, however it uses a radioactive source that is a potential health hazard and therefore requires strict handling, storage and maintenance of the equipment to maintain safety standards. The Electrical Density Gauge (EDG) is an alternative in-situ test that is quicker, safer and easier to maintain since it uses electric current to measure the compaction characteristics of the soil. The objective of the study was to determine the repeatability, accuracy and applicability of the EDG on South African soils by comparing its measurements for dry density and moisture content in the laboratory and in the field to the results from the sand cone and oven method. In the laboratory, a clean sand and a clayey sand were tested at the optimum moisture content and at ± 3% of the optimum moisture content. The soils were compacted to 200 mm using the RT74 rammer and the compaction values first tested using the EDG then followed by the sand cone test at the centre of the EDG test spot. The moisture content of the excavated sample from the sand cone test was determined using the oven method. For the field tests, the compaction characteristics of a sandy gravel and three uniformly graded sands were tested in-situ using the EDG followed by the sand cone test. Overall, the EDG measurements were repeatable based on test-retest comparison of the paired measurements. EDG results for moisture content were consistent with the values obtained from the laboratory oven method especially in the uniformly graded sands. However, the density measurements differed from the results of the sand cone test, which was considered the reference test for determination of field soil density. It is recommended that the EDG calibration relationship for bulk density be revised in order to improve the accuracy of the density measurements.