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  • 1401.
    With, Christoffer
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Jord- och bergmekanik.
    Larsson, Stefan
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Jord- och bergmekanik.
    Bodare, Anders
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Jord- och bergmekanik.
    Lime-cement columns as wave barrier against train-induced vibrations2007Inngår i: Geotechnical Engineering in Urban Environments: Proceedings of the 14th European Conference on Soil Mechanicsand Geotechnical Engineering / [ed] V. Cuéllar, E. Dapena, E. Alonso, J.M. Echave, A. Gens, J.L. de Justo, C. Oteo, J.M. Rodríguez-Ortiz, C. Sagaseta, P. Sola, A. Soriano, 2007, s. 1397-1401Konferansepaper (Fagfellevurdert)
  • 1402.
    Xintao, Liu
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geodesi och geoinformatik.
    Bin, Jiang
    Geomatics, University of Gävle.
    Defining and generating axial lines from street center lines for better understanding of urban morphologies2012Inngår i: International Journal of Geographical Information Science, ISSN 1365-8816, Vol. 26, nr 8, s. 1521-1532Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Axial lines are defined as the longest visibility lines for representing individual linear spaces in urban environments. The least number of axial lines that cover the free space of an urban environment or the space between buildings constitute what is often called an axial map. This is a fundamental tool in space syntax, a theory developed by Bill Hillier and his colleagues for characterizing the underlying urban morphologies. For a long time, generating axial lines with help of some graphic software has been a tedious manual process that is criticized for being time consuming, subjective, or even arbitrary. In this paper, we redefine axial lines as the least number of individual straight line segments mutually intersected along natural streets that are generated from street center lines using the Gestalt principle of good continuity. Based on this new definition, we develop an automatic solution to generating the newly defined axial lines from street center lines. We apply this solution to six typical street networks (three from North America and three from Europe), and generate a new set of axial lines for analyzing the urban morphologies. Through a comparison study between the new axial lines and the conventional or old axial lines, and between the new axial lines and natural streets, we demonstrate with empirical evidence that the newly defined axial lines are a better alternative in capturing the underlying urban structure.

  • 1403.
    Yaghoobi Rafi, Jalaleddin
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Jord- och bergmekanik.
    Design approaches for grouting of rock fractures; Theory and practice2013Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Currently, cement base grout is used widely for sealing of the rock fractures in order to decrease the permeability of rock mass. Grouting procedure is one of the main tasks in cycle of rock excavation. In addition, huge amount of grout should be used during dam construction in order to seal the bedding and embankment walls. Therefore, considering the effect of grouting in duration and cost of the project, improving the design methods seems essential.

    In successful grouting the goal is to achieve the required sealing of fractures while avoiding ground movement due to applied pressure. Empirical methods have been developed to decide the pumping pressure, grout mix properties and stop criteria in order to fulfill requirements of successful grouting but there are ambiguities in using them and performance of them have been questioned. In these methods, assumptions and criteria are based on rules of thumbs and experiences from previous projects. The main uncertainties connected to these methods are identifying amount of grout spread and state of the fracture.

    Theoretical approach is an analytical solution which provides the chance for estimation of penetration length of the grout in real time. Furthermore, void filling fracture aperture and trend of the grout flow are estimated. As the development of this theory, elastic and ultimate jacking limits have been established based on the estimated penetration length. Therefore, it is possible to identify jacking of the fracture and estimate the state of the fracture in real time. 

    In this research work, performance of this theoretical approach which is called “Real Time Grouting Control Method” has been validated through case studies. Properties of the used material, data for pressure and flow in addition to geological characteristics have been gathered from projects in sedimentary rock (Gotvand Dam in Iran and THX Dam in Laos) and hard rock (City Line Project in Sweden). This theory made it possible to observe overflow of grout and jacking of the fractures in sedimentary rock. In place of hard rock with mostly vertical fractures, this theoretical approach confirms usage of higher pressure which will shorten the grouting time.

    In this research work, variation in properties of the grout mix during grouting has been neglected. moreover, orientation of the fracture and its deformation due to injection pressure are not considered. Despite these assumptions, the results were promising and performance this approach in estimation of grout spread and identifying jacking of the fracture has been verified.

  • 1404.
    Yaghoobi Rafi, Jalaleddin
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Jord- och bergmekanik.
    Study of Pumping Pressure and Stop Criteria in Grouting of Rock Fractures2014Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Today practice of grouting is based on empirical approaches in that, pumping pressure and stop criteria are determined by benchmarking similar projects. Considering a maximum limit for grouting pressure would allow applying a relatively high pressure that may lead to jacking of the fracture or even uplift of the rock mass. On the other hand, keeping the pressure lower than the overburden, in order to avoid any deformation, will prolong grouting process. Determination of pumping pressure is more complicated considering the induced energy to the rock fracture due to combination of the injected volume and pumping pressure. In other word, pressurizing large volume of the injected grout with a low pumping pressure establish the same force inside the fracture as the high applied grouting pressure on small injected volume do. Therefore, an stop criterion to limit grouting volume along with grouting pressure, which is a hyperbola trimming maximum pressure-maximum volume limits and  named as grout intensity number (GIN), has been defined. However, in using this stop criterion and at completion point, the state of the fracture and the distance that grout spread inside the fracture are unknown. As a theoretical approach, examining the flow of the Bingham fluid in network of fractures led to development of a numerical model and later an analytical solution, which enabled estimation of distance that grout spread in the fractures in real time. Finally, theoretical curves to limit elastic and ultimate jacking were established to limit grout pressure in correlation with depth of grout penetration by considering the state of the fracture.  

    Despite empirical and theoretical developments, determination of optimum grouting pressure is still challenging. In this study, In addition to examining performance of the analytical solution in estimation of grout spread and distinguishing onset of fracture jacking, the goal is coming up with recommendations for selection of optimum grouting pressure, by examining mechanism of elastic jacking. For this purpose, negative aspects of fracture deformation, which are increase of grouting time and remaining transmissivity, were quantified and discussed against its positive effect on increase of penetrability. By that, application of a relatively high pressure was recommended in order to opening of the fracture to a permitted level, with purpose of increasing penetrability while considering negative effects of elastic jacking. The stop criterion is defined as the grouting time of achieving the required distance of grout spread at the highest applicable grouting pressure.

    In examining empirical methods, in grouting of fractures in deep levels, pressure-depth graph suggests usage of higher pressure in compare with the estimated pressure by theory while GIN method is conservative. In further studies GIN was estimated analytically and applying a relatively high grouting pressure in order to opening the fracture, up to attaining the hyperbola, and continuation of grouting with decreasing trend, in order to bringing the fracture back to its initial size at refusal, were proposed. Complexity of using this methodology in compare with theoretical approach was discussed.

    As the future work, there is a need to verify the results in the field, and to confirm well performance of this analytical solution in different geologies. Examining variation of grout mixture properties during grouting program as well as significance of simplification of geological pattern to a single horizontal fracture, in that grout flow radially, are among other future studies that can develop this theoretical application further.  

  • 1405.
    Yaghoobi Rafi, Jalaleddin
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Jord- och bergmekanik.
    Fereidouni, Hamidreza
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Jord- och bergmekanik.
    Stille, Håkan
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Jord- och bergmekanik.
    Robustness of Theories and Newly Developed Methods for Cement Base Grouting Works2012Konferansepaper (Annet vitenskapelig)
  • 1406.
    Yaghoobi Rafi, Jalaleddin
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Jord- och bergmekanik.
    Stille, Håkan
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Jord- och bergmekanik.
    Applicability of using GIN method, by considering theoretical approach of grouting design2015Inngår i: Geotechnical and Geological Engineering, ISSN 0960-3182, E-ISSN 1573-1529, Vol. 33, nr 6, s. 1431-1448Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In the practice of grouting of fractured rock, currently, empirical methods are used. Amongst them, the GIN method is popular mostly in Europe and has been tried in many projects. The concept of this method is to limit the combination of pressure and injected volume to a specific grout intensity number in order to control the energy induced in the rock fractures and to avoid uplift. However, difficulties in employing this method have been reported, which are mainly due to uncertainties in recognizing the distance of grout penetration and the state of the fractures during grouting and at the completion grouting. In this paper, the purpose has been examining the applicability of the GIN method by defining the characteristic curve of the P·V diagram (referred to here as the hyperbola) and suggesting appropriate completion criteria based on the radius of grout spread around the borehole. This will provide the chance to assign a permitted level of fracture deformation (or jacking) to the GIN by considering the formulation of fracture deformation based on grout propagation in a previously developed theoretical approach by Stille et al. (Geotech Geol Eng 30:603–624, 2012) as a part of the Real Time Grouting Control Method. Thus, in attaining the hyperbola, the identified radius of grout spread is achieved and the resulting fracture deformation at this completion point can be beneficial in improving penetrability. However, if the full extent of this deformation extends beyond the grouted zone, part of the fracture may remain un-grouted, and this will affect the sealing efficiency of the grouting program. This may be continued by selecting a smaller GIN and reducing the grouting pressure as the real time pressure–volume plot moves along the hyperbola, which will bring the fracture back to its initial state as grouting approaches the completion point, i.e. when the grout has spread to the desired distance. This hypothesis has been examined against the grouting works performed in three different real projects, for which the grouting parameters can be determined from the available grouting records. It is concluded that the GIN used in practice was much higher than the theoretically estimated values obtained through the proposed analytical solution. Furthermore, in the grouting of fractures close to the surface, the radius of grout spread impacts the GIN significantly, and only a limited grouting pressure is applicable, thus in using split spacing technique in such circumstances, different GINs should be selected for different sets of boreholes to obtain enough propagation at the maximum applicable pressure. The introduced analytical solution introduced in this paper can be a useful procedure for designing the GIN based on the grout spread. Nevertheless, it becomes complicated in dealing with fracture deformation. In a difficult grouting case where the demand for sealing is high, the recommendation is to use the proposed theoretical approach, which provides detailed information during the actual grouting procedure, by estimation of the radius of grout spread and the state of the fracture in real time

  • 1407.
    Yaghoobi Rafi, Jalaleddin
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Jord- och bergmekanik.
    Stille, Håkan
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Jord- och bergmekanik.
    Control of rock jacking considering spread of grout and grouting pressure2014Inngår i: Tunnelling and Underground Space Technology, ISSN 0886-7798, E-ISSN 1878-4364, Vol. 40, s. 1-15Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper describes a theoretical approach for monitoring fracture dilatancy (or “jacking”) during grouting. From this, a methodology to optimize the grout pumping pressure has been developed, based on the required penetration length (i.e. the distance that the grout spreads from the grout hole into the network of fractures within the rock mass). Empirical rules are put forward to prevent the damage that may result from uncontrolled deformation (Jacking) of the fractures, by limiting either pumping pressure or the injected grout volume, or by a combination of both. The state of the fractures and the spread of the grout when these limits are reached are discussed. The theoretical approach, which is referred to here as the Real Time Grouting Control Method, enables the estimation of grout penetration length or “spread” in real time. This gives an opportunity to monitor fracture dilation as it happens and, for the purpose of this paper, the allowable limits of elastic deformation and jacking have been estimated based on the grout spread. Two case histories are analyzed, for which the physical reaction of the fracture deformation with time and grout spread are determined from the recorded pressure and flow. By comparing the observed physical reaction with the theories for jacking presented here, the Real Time Grouting Control Method has been validated, and it is shown that this theoretical approach is superior to commonly used empirical methods, in that it allows the optimization of the pumping pressure to achieve a given penetration length in the shortest time and with an acceptable fracture dilatancy. This approach is a major step forward in customizing grouting works.

  • 1408.
    Yaghoobi Rafi, Jalaleddin
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Jord- och bergmekanik.
    Stille, Håkan
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Jord- och bergmekanik.
    Bagheri, Mehdi
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Jord- och bergmekanik.
    Applying Real Time Grouting Control Method in Sedimentary Rock2012Inngår i: Grouting and deep mixing: proceedings of the fourth International Conference on Grouting and Deep Mixing, February 15-18, 2012, New Orleans, Louisiana, American Society of Civil Engineers (ASCE), 2012, s. 1450-1459Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We report on preliminary studies of low (14 at.%) and high (53at.%) concentration Mn doped MgO films deposited by co-sputtering from metallic Mn and Mg targets. The structural, surface morphologies and magnetic properties of the films of different thickness were studied. All the as grown films are found to be amorphous and film surfaces are found to be flawless and homogeneous. We observe at room temperature robust ferromagnetic loops with a saturation magnetization value that is a function of film thickness reaching a maximum of ≃38.5 emu/cm3 in the Mn0.53Mg0.47O film at a thickness of ≃92 nm. In thicker films room-temperature ferromagnetic ordering is suppressed and eventually at a thickness around 120nm the expected diamagnetism of the bulk appears. The origin of ferromagnetism may be attributed to cation defects at the Mg-site.

  • 1409.
    Yaghoobi Rafi, Jalaleddin
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Jord- och bergmekanik.
    Tsuji, Masakuni
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Jord- och bergmekanik.
    Stille, Håkan
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Jord- och bergmekanik.
    Theoretical approaches in grouting design: estimation of penetration length and fracture deformation in real time2013Inngår i: Bergmekanikdagen, 2013Konferansepaper (Annet vitenskapelig)
  • 1410.
    Yaghoobi Rafi, Jalaleddin
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Jord- och bergmekanik.
    Tsuji, Masakuni
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Jord- och bergmekanik.
    Stille, Håkan
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Jord- och bergmekanik.
    Theoretical Approaches in Grouting Fractures of the Rock Mass: Theories and Applications2013Inngår i: 47th US Rock Mechanics / Geomechanics Symposium, American Rock Mechanics Association (ARMA), 2013, s. 1731-1737Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Currently there is a great deal of specific attention on improving the grouting methods since optimizing the grouting process will have significant impact on performance and economy of projects as well as safeguarding the purity of nature. The main problem with existing grouting method is lack of knowledge about the spread of grout, i.e. there is no clue if the grout has been penetrated enough or if it has been over spread. Also the state of fractures during grouting is unknown. In the last decade, theoretical approach has been developed which enables estimation of the grout spread in real time. Furthermore, by replacing the estimated penetration length with injected volume, dilation of the rock fractures is monitored in real time. In this paper, this analytical solution has been examined and competency of its application has been discussed. Implementing this theory with data from City Line project confirms the usage of high applied pressure in this project which will lead to shortening of the grouting time.

  • 1411.
    Yang, Ting
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Borehole sealing with expandable buffer clays in HLW disposal: Lab-scale performance2015Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Two basically different multibarrier concepts for high-level radioactive waste (HLW) are the often cited KBS-3 V/H concepts, for isolating nuclear waste at 400-600 m depth and Very Deep Boreholes concepts (VDH) for placement at 2000-4000 m depth. Both make use of expandable clay as isolating medium of canisters with HLW and as backfill material in shafts and tunnels in repositories for safe disposal of such waste. This licentiate thesis is based on three papers related to the properties of clays for use as engineered barriers, and to their performance at geological disposal. The first paper deals with the buffer criteria for the two disposal concepts. In this paper the possibilities and limitations of using clays of montmorillonite-, saponite- and mixed layer clay type are considered. The second paper discusses the swelling property and permeability of Na-montmorillonite clays (MX-80, GMZ) and illite-smectite mixed layer clay (Holmehus) saturated and percolated by distilled water and a salt solution. The third paper describes a lab-scale performance of VDH holes sealing using Holmehus clay. In this paper, methods for solving the problem of too quick hydration of the dense clay are investigated and evaluated.

  • 1412.
    Yang, Ting
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Maturation of Clay Seals in Deep Bore Holes for Disposal of Radioactive waste: Theory and Experiments2017Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    KBS-3 and very deep borehole (VDH) concepts are two major types of long-term geologicaldisposal methods for high-level radioactive waste (HLW) isolating from the biosphere. TheKBS-3V concept for isolating the HLW at the depth of 400-500 m, is the officially proposedoption in Sweden and has been the subject of considerable research in the past few decades,while the VDH concept was considered as an option in the 1950s but later became discouragedbecause of insufficient experience in drilling technology. The greatest merit of the VDHconcept is that the almost stagnant groundwater in the deep boreholes prevents the transport ofthe possible release of radionuclides into the rock or up to the ground level. Since variousdisadvantages of the KBS-3V concept were found in previous research, the superiority of VDHconcept attracted the researchers to continue studying it into the late 1980s.The geological repositories of both of KBS-3V and VDH types primarily consist of a naturalbarrier (host rock) and of an engineering barrier (also known as a buffer/backfill barrier).According to the principle of IAEA and national relative research organizations, thebuffer/backfill material should have low permeability and good expandability, as well assuitable physical and sealing properties.The thesis concerns the VDH concept and is focused on the construction and performance ofthose parts of the sealed repository that are not affected by high temperature or gamma radiation.In the lower part of a VDH repository, the clay packages containing HLW will be exposed tohigh temperature (100-150 􀄇 ) in the borehole and to highly saline groundwater. In theinstallation phase of HLW, the groundwater will be pumped out and replaced by medium-softsmectite clay mud in which the HLW packages are installed vertically. During the hydrationand maturation of the clay components, the microstructural reorganization, water transport,migration of clay particles and redistribution of the density of the components take place. Thematuration determines the transient evolution of the clay seals and influences the rheologicaland soil mechanical behavior in the installation phase. The maturation of clay system alsodetermines their ultimate sealing potential of VDH repositories.This study presents the work carried out for investigating the maturation of the buffer-backfillclay in the HLW deep borehole. Initially in the study three types of clays, the Namontmorillonite,magnesium-rich and illite-smectite mixed layer clays, were examined for estimating their performance as the barrier candidate material. This is mainly presented in theliterature review. The experimental study was conducted on montmorillonite GMZ clays andI/S mixed-layer Holmehus clay. The expandability and permeability tests were carried out forinterpretation of the recorded swelling development and assessment of the effect of the salineconditions, with the goal of deriving a relationship between swelling pressure and hydraulicconductivity for different dry densities. The maturation tests of initially fully-saturatedHolmehus clay and partly saturated GMZ clay were performed. During the tests, the shearstrength mobilised by the relative movement of densified mud and migrated dense clay -contained in a perforated central tube - were determined. According to the results of shearstrength tests, the maximum operation time or the number of clay packages to be placed in asingle operation was evaluated, whilst the suitable saturation degree of the dense clay wasdiscussed as well.A model of the maturation of initially water-saturated clay seals based on Darcy’s law wasworked out and the evolution of the clay components in a lab-scale borehole using Holmehusclay were performed and compared with the experimental recordings. Good agreementsbetween the physical behaviors of the theoretical simulations and the measurements wasachieved by which the validity of the model was verified. Using the results, the hydration andsoil migration in the entire maturation process were presented in diagram. The model was alsoused for preliminary evaluation of the maturation products in real boreholes by assuming thesame Holmehus clay as used in the tests. Two constellation of borehole and dense clay withdifferent diameters, 80 cm borehole /60 cm clay and 80cm/50cm, were assumed. The resultsrespecting dry density and hydraulic conductivity of the ultimate maturation products, and thedegree of homogeneous of the buffer and backfill clay system in the assumed boreholes, arepresented and discussed. The options of different mineral types and initial physical propertiesof the candidate buffer clays provide a reference for engineering barrier design of HLW disposalin VDH.

  • 1413.
    Yang, Ting
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Xiaodong, Liu
    East China Institute of Technology, Fuzhou, Jiangxi.
    Swelling properties and permeability of expandable clays of potential use for nuclear waste disposal2016Inngår i: Journal of Earth Sciences and Geotechnical Engineering, ISSN 1792-9040, E-ISSN 1792-9660, Vol. 6, nr 2, s. 49-61Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Bentonite clay has attracted considerable attention as isolating material for safe disposal of high-level radioactive nuclear waste (HLW) on account of its low hydraulic conductivity and high swelling capacity. In the presently described study, three candidate smectitic clay materials were investigated and compared with respect to hydraulic conductivity and expandability. The clay samples were prepared from desiccated and crushed raw material placed and compacted in oedometer cells for saturation with distilled water and 3.5% CaCl2 solution in separate test series to a density at fluid saturation of 1200 ~ 1900 kg/m3. The samples were tested with respect to the hydraulic conductivity and swelling capacity. The MX-80 and Homehus clays matured as expected giving a successively monotonous increase in swelling pressure during the wetting process while GMZ clay showed two pressure peaks. The pressure development was different for low and high densities and can be explained by crystal expansion via interlamellar wetting, followed by osmotic swelling including establishment of electrical double-layers. The phenomena can alternatively be explained by the microstructural changes when clay minerals absorb solutions in the hydration phase. Differences in granule size distributions and mineral composition can explain different swelling abilities and permeabilities.

  • 1414.
    Yang, Ting
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Pusch, Roland
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Liu, Xiaodong
    East China University of Technology.
    Assessment of clay buffers for isolating HLW2014Inngår i: Waste Management and The Environment VII / [ed] C.A. Brebbia; G. Passerini; H. Itoh, Southampton: WIT Press, 2014Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Great effort is put on finding optimal buffer clays for isolating highly radioactive waste (HLW) in countries utilizing nuclear energy. Different materials are required to provide a hydrologically and mechanically suitable surrounding of canisters with highly radioactive waste in repositories in crystalline rock. For shallow disposal the high hydraulic conductivity of the rock makes very dense smectite-rich clays necessary while for disposal in very deep holes the primary desire is to use smectitic clays with a potential to resist high temperatures. In both cases montmorillonite, with Al being a dominant lattice ion in the octahedral layer, is suitable, but saponite with Mg as dominant octahedral constituent can be preferable for deep disposal. For both concepts use of smectitic mud is an option for supplying the buffer with water from start and for controlling the hydration rate.

  • 1415.
    Yang, Ting
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Pusch, Roland
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Liu, Xiaodong
    East China University of Technology.
    Lab testing of method for clay isolation of spent reactor fuel in very deep boreholes2015Inngår i: Vol. 15, s. 152-158Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In Sweden and Finland and some other countries, two basically different multibarrier concepts for disposal of spent reactor fuel (HLW) are the often cited KBS-3 methods and Very Deep Boreholes methods (VDH), on which the paper focuses. These concepts have engineered barriers in the form of clay-embedded canisters with spent reactor fuel.. The clay, placed around the canisters and between them, provides ductility and tightness for minimizing the risk of canister breakage, and for tightness. The large-diameter VDH holes have dense clay seals of smectite-rich material in combination with clay mud for stabilization of the rock. In this paper, clay mud of smectite-rich Danish Holmehus clay was investigated for evaluating the physical interaction with the dense clay blocks. The possibility of solving the problem of too quick hydration of the blocks, which can make the resistance to insertion of the units of dense clay and canisters (“supercontainers”) in the mud difficult, was investigated by using prewetted dense clay blocks prepared by a new method (“DW” technique). The laboratory experiments, which were made to simulate the installation of supercontainers in clay mud using model versions of them, have given promising results.

  • 1416.
    Yao, Yu
    Luleå tekniska universitet.
    A laboratory study of mechanical characteristics of a marine soil1987Rapport (Annet vitenskapelig)
  • 1417.
    Yao, Yu
    Luleå tekniska universitet.
    Offshore geotechnical investigations in South China sea1987Rapport (Annet vitenskapelig)
  • 1418.
    Yaseen, Zaher Mundher
    et al.
    Sustainable Developments in Civil Engineering Research Group, Faculty of Civil Engineering, Ton Duc Thang University, Ho Chi Minh City, Vietnam.
    Ehteram, Mohammad
    Department of Water Engineering and Hydraulic Structures, Faculty of Civil Engineering, Semnan University.
    Sharafati, Ahmad
    Civil Engineering Department, Science and Research Branch, Islamic Azad University, Tehran.
    Shahid, Shamsuddin
    School of Civil Engineering, Universiti Teknologi Malaysia (UTM).
    Al-Ansari, Nadhir
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    El-Shafie, Ahmed
    Civil Engineering Department, Faculty of Engineering, University of Malaya, Kuala Lumpur .
    The Integration of Nature-Inspired Algorithms with Least Square Support Vector Regression Models: Application to Modeling River Dissolved Oxygen Concentration2018Inngår i: Water, ISSN 2073-4441, E-ISSN 2073-4441, Vol. 10, nr 9, artikkel-id 1124Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The current study investigates an improved version of Least Square Support Vector

    Machines integrated with a Bat Algorithm (LSSVM-BA) for modeling the dissolved oxygen (DO)concentration in rivers. The LSSVM-BA model results are compared with those obtained using M5Tree and Multivariate Adaptive Regression Spline (MARS) models to show the efficacy of this novelintegrated model. The river water quality data at three monitoring stations located in the USA areconsidered for the simulation of DO concentration. Eight input combinations of four water quality parameters, namely, water temperature, discharge, pH, and specific conductance, are used to simulate the DO concentration. The results revealed the superiority of the LSSVM-BA model over the M5 Tree and MARS models in the prediction of river DO. The accuracy of the LSSVM-BA model compared with those of the M5 Tree and MARS models is found to increase by 20% and 42%, respectively, in terms of the root-mean-square error. All the predictive models are found to perform best when all the four water quality variables are used as input, which indicates that it is possible to supply more information to the predictive model by way of incorporation of all the water quality variables.

  • 1419.
    Yassin, Ali
    et al.
    Iraq Geological Survey, Baghdad.
    Alabidi, Abdulkadhim
    Department of Geology, Faculty of Science, University of Kufa.
    Hussain, Mohammed
    Babylon University.
    Al-Ansari, Nadhir
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Copper Ores in Mawat Ophiolite Complex(Part of ZSZ) NE Iraq2015Inngår i: Natural Resources, ISSN 2158-706X, E-ISSN 2158-7086, Vol. 6, nr 10, s. 514-526Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Ore microscopy study for some samples from Mawat complex NE Iraq (part of Zagros Suture Zone) showed the presence of copper ore minerals was irregularly distributed, mainly throughout the basic rocks of Mawat Ophiolite Complex. The main sulfides minerals identified were: chalcopyrite, pyrite, bornite, chalcocite and covellite. Iron hydroxides/oxides including goethite and magnetite were also observed associated with sulfide ore. Chalcopyrite and pyrite were the main primary minerals from which other ores were formed. They were originated at the orthomagmatic stage, and also deposited from aqueous solution of final stage in the consolidation of a magma forming vein textures which was observed in many samples. Two types of pyrite generations were recognized. They were pre-tectonic pyrite and post-tectonic pyrite. The secondary recognized ore textures were rim, pseudo morph, zoning, relicts, atoll and vein replacement textures. Secondary textures resulting from exsolution were also presented. Three stages of mineralization could be concluded: orthomagmatic stage (Earliest), the hydrothermal activations stage (Hypogene) and the weathering stage (Supergene). Paragenaticaly, the primary copper sulfides including chalcopyrite and bornite were responsible for other copper ores formation. These minerals were observed disseminated throughout the host mafic rocks which were considered as endogenic deposits (magmatic and hypogene origin) and they were modified as small patches of chalcocite and covellite.

  • 1420.
    Yederulh, Hulumtaye Kefyalew
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Jord- och bergmekanik.
    Settlement calculation for lime/cement column improved clay: Analytical and numerical analyses related to a case study2018Independent thesis Advanced level (degree of Master (Two Years)), 80 poäng / 120 hpOppgave
    Abstract [en]

    The dry deep mixing method is widely used to improve a soft clay soil to increase the shear strength as well as to reduce the time for consolidation. It is a mechanical mixing process that makes parts of the soil stiffer than its original strength. It is mainly applicable to soft clay or peat soil.

     

    In this master thesis, the objective was set to perform a comparative analysis on the prediction of the settlements of a clay soil improved by lime/cement columns (LCC). The theoretical settlement predictions were made using two analytical and numerical modeling. A case study was carried out on a part of Stockholm bypass project where LCC was applied to improve soft clay for a foundation of a concrete trough. Field measurements of the vertical deformation of the improved soil were performed using settlement plates to compare the analytical and numerical results.

    The first analytical method was performed based on the recommendation of TK Geo 13 (2013) while the second method was performed based on the concept of a composite ground. In the case of the numerical method, FEA was performed using 2D plane strain model in Plaxis simulation. The performance of the geometry and combined matching models were investigated to convert the axisymmetric to plane strain model. The variation in stiffness of the columns were taken into consideration by applying two stiffness values 30 and 33 MPa for the upper and lower half of the column respectively. A preload of 58 kPa was applied on the improved clay soil to simulate the time-dependent consolidation settlement due to the stress addition.

    A comparison was carried out between the results obtained from the analysis and a field measurement. The two analytical methods produced a better agreement with the field measurement regarding long-term consolidation settlement and a reasonable agreement concerning the rate of consolidation. The numerical analysis showed a good agreement with the benchmark concerning both the long-term consolidation settlement as well as the rate of consolidation. The geometry matching model gave a reasonable result regarding correctness of the result compared with the combined matching. Based on the results obtained in this study, the numerical methods had a better agreement with the measurements.

  • 1421.
    Yi, Changping
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Sjöberg, Jonny
    Itasca Consultants AB.
    Johansson, Daniel
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Petropoulos, Nikolaos
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    A numerical study of the impact of short delays on rock fragmentation2017Inngår i: International Journal of Rock Mechanics And Mining Sciences, ISSN 1365-1609, E-ISSN 1873-4545, Vol. 100, s. 250-254Artikkel i tidsskrift (Fagfellevurdert)
  • 1422. Young, Raymond N.
    et al.
    Nakano, Masashi
    Pusch, Roland
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Environmental soil properties and behaviour2012Bok (Fagfellevurdert)
    Abstract [en]

    Examining the many changes in soil properties and behavior as a result of stresses from both anthropogenic and environmental forces, this critical work details the requirements of soils to maintain their design engineering properties (rheological, transmission, buffering, and ion-accumulation) over their projected life-spans. It discusses the use of soils as engineered materials in the construction of structures on and in the ground, including foundations, bridges, nuclear waste repositories, tunnels, and other civil infrastructures. The book presents numerous laboratory tests, procedures, techniques, data gathering, data reduction models, and analyses of soil structure.

  • 1423.
    Yu, Y.
    et al.
    Luleå tekniska universitet.
    Axelsson, Kennet
    Luleå tekniska universitet.
    Li, Z. Q.
    Interaction between soil and bored pile based on field tests1991Inngår i: Field measurements in geomechanics: proceedings of the 3rd international sysmposium Oslo / [ed] Geraldine Sorum, Rotterdam: Balkema Publishers, A.A. / Taylor & Francis The Netherlands , 1991, s. 799-808Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Three long instrumented bored piles have been tested in the ground of a multilayer soil of clay and sand. The shaft load transfer mechanism was investigated with regard to the soil type, pile geometry and test procedures. Additional pile tests of large displacement penetration have also been carried out to study the performance of tip resistance. Special attention is given to the installation procedure of piles, which may play a significant role in the performance of the bored piles.

  • 1424.
    Yu, Yan
    Luleå tekniska universitet.
    Silty landslides in the river valleys of northern Sweden1994Inngår i: Proceedings: Seventh International Congress, International Association of Engineering Geology, 5-9 September 1994, Lisboa Portugal / [ed] R. Oliveira, Rotterdam: Balkema Publishers, A.A. / Taylor & Francis The Netherlands , 1994, s. 1731-1740Konferansepaper (Fagfellevurdert)
  • 1425.
    Yu, Yao
    Luleå tekniska universitet.
    Constitutive relations for soils and their verifications: a report on the level of development of geomaterial modelling : a state-of-the-art report1988Rapport (Annet vitenskapelig)
  • 1426.
    Yu, Yao
    Luleå tekniska universitet.
    Stability of embankments on sulphide-rich soils1994Rapport (Annet vitenskapelig)
  • 1427.
    Yu, Yao
    Luleå tekniska universitet.
    Testing and modelling of silty and sulphide-rich soils1993Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Silt and sulphide soil are two types of soil which are dominating in northern Sweden, especially in the coast area of the Baltic sea. The stress-strain and strength characteristics of these two soils have so far not been as much explored as those for e.g. Scandinavian clays. With increasing use of numerical methods in geotechnical engineering, better knowledge of the constitutive behaviour of soils is needed as well as more accurate models. The work reported in this thesis is an attempt to achieve such a knowledge for silt and sulphide soil. The drained and undrained stress-strain characteristics of silt have been investigated by means of triaxial compression and extension tests. The compressibility, the dual characteristic of contractancy and dilatancy during shearing, the effect of the clay content and the dependence of the failure surface on the Lode angle have been specially discussed. The drained and undrained stress-strain characteristics of sulphide soil were investigated by means of triaxial and CRS oedometer tests. The compressibility, the effect of the excess pore pressure and the anisotropy have been specially discussed. A plasticity model was proposed for modelling the constitutive behaviour of silt. Among others, the model takes into account the dual characteristic and the dependence of the yield criterion on the Lode angle. An analytical solution was carried out for the undrained triaxial state which links the dilatancy parameter to other parameters. Conditions of material stability were also derived for the triaxial stress state. A plasticity model was proposed for modelling the constitutive behaviour of sulphide soil. Among others, the model takes into account the cohesion and the initial and stress-induced anisotropy. An explicit relation was derived to relate failure or critical state parameters in the isotropic case to those in the anisotropic (K0) case. A calibration method based on optimization was designed to improve the overall quality of model parameters. By using this method, the two proposed models were then calibrated to experimental data from several sets of tests on silt and sulphide soil. Two boundary-value problems, with available data from field tests, were analyzed using a finite element code with the proposed models implemented to demonstrate the capability of the proposed models and of the numerical method.

  • 1428.
    Yu, Yao
    Luleå tekniska universitet.
    Three-dimensional finite element analyses of pile group foundations1993Rapport (Annet vitenskapelig)
  • 1429.
    Yu, Yao
    et al.
    Luleå tekniska universitet.
    Axelsson, Kennet
    Luleå tekniska universitet.
    A plasticity model for silt1992Inngår i: Numerical models in geomechanics: of the fourth International Symposium on Numerical Models in Geomechanics, NUMOG IV, Swansea, U.K., 24-27 August 1992 / [ed] G.N. Pande; S. Pietruszczak, Rotterdam: Balkema Publishers, A.A. / Taylor & Francis The Netherlands , 1992, Vol. 4, s. 37-45Konferansepaper (Fagfellevurdert)
  • 1430.
    Yu, Yao
    et al.
    Luleå tekniska universitet.
    Axelsson, Kennet
    Luleå tekniska universitet.
    Constitutive driver for response behaviour of soils1992Rapport (Annet vitenskapelig)
  • 1431.
    Yu, Yao
    et al.
    Luleå tekniska universitet.
    Jacobsson, A.
    Geological and geotechnical characteristics of tills for road construction1994Inngår i: Proceedings: Seventh International Congress, International Association of Engineering Geology, 5-9 September 1994, Lisboa Portugal / [ed] R. Oliveira, Rotterdam: Balkema Publishers, A.A. / Taylor & Francis The Netherlands , 1994, s. 3235-3243Konferansepaper (Fagfellevurdert)
  • 1432.
    Zainy, Maher T.
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Al-Ansari, Nadhir
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Bauer, Tobias
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Ask, Maria
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    The Tectonic and Structural Classifications of the Western Part of the Zagros Fold and Thrust Belt, North Iraq, Review and Discussion2017Inngår i: Journal of Earth Sciences and Geotechnical Engineering, ISSN 1792-9040, E-ISSN 1792-9660, Vol. 7, nr 2, s. 71-89Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The Zagros fold and thrust belt represents a tectonically significant area, and one of the richest areas in oil and gas reservoirs in the world. The Zagros fold and thrust belt is the deformational product of the Cretaceous-present day convergence of the Arabian and Iranian (Eurasian) plates (subduction and collision). The belt extends more than 2000 km from southern Turkey through the north and northeastern Iraq to the Strait of Hormuz in southwestern Iran. The Zagros fold and thrust belt is divided into two parts which are; Western part within Iraqi region and Eastern part within Iranian region. The western part of the Zagros fold and thrust belt has been traditionally subdivided into several structural zones that are generally striking parallel to the plate boundary. This is characterized by exposure of Late Ordovician to Pliocene - Pliestocene formations with different types of Quaternary Sediments. This research will concentrate on Western part of Zagros fold and thrust belt and the styles of structural classifications, which will aid to clarify and better understand the tectonic and structural history and evolution of the region. We have considered the last version of structural classification as the most relevant one to the reality, especially within outer platform (Unstable shelf). Where it divides the region into four structural zones, which are: Low Folded zone, High Folded Zone, Imbricate Zone, and Zagros Suture Zone and these zones were further divided to several subzones. This classification is based on the structural style and intensity of deformation, stratigraphy, mechanicalstratigraphy and tectono-stratigraphy of the deformed sequences, Age of deformation, surface physiography and morphology. The data used in the classification is more reliable, up to date and relevant.

  • 1433.
    Zakaria, Saleh
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Rain water harvesting and supplemental irrigation at Sinjar district in northwest Iraq2012Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    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 deals with rainwater harvesting modeling on Sinjar District. The area of study is a plan area located on the northern and southern flank of Sinjar Mountain, within Nineveh province in northwest Iraq. The model was first applied on southern of Sinjar Mountain, where barley crop was chosen as one of the main crops grown in the area. Linear programming technique was adopted to optimize the irrigated area for irrigation scenario of supplemental irrigation (SI) 100% of full irrigation requirements. Two scenarios of 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 a basin were operated as one system. Both scenarios gave encouraging results. Scenario two however, was relatively better.And then the model was applied again on the northern Sinjar Mountain area. Wheat crop was considered as the main crop grown in the area. A linear programming technique was adopted to optimize the irrigated area for three scenarios of irrigation. They were: 1/supplemental irrigation (SI) 100%, 2/deficit irrigation (DI) 50%, 3/deficit irrigation (DI) 25% of full irrigation requirements. 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. These results reflect useful value of RWH and its influence to increase the irrigated area in the studied region.This study had been carried out at Lulea University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Lulea, Sweden.The present work structured in seven chapters, and can be pursued as follows: In chapter 1, Background of the rainwater harvesting, aims of study and research methodology are addressed. In chapter 2, Scope of description of Water Resources in Iraq, Numbers and facts about Iraq, Present water resources conditions in Iraq, Irrigation practices in Iraq, Main Rivers of Iraq, Dams on Tigris and Euphrates Rivers, The impact of Southeastern Anatolia Project (GAP) on water resources in Iraq, Environmental Consequences and Groundwater in Iraq are described.In chapter 3, Information review on rainwater harvesting and supplemental irrigation is presented. In chapter 4, Description of the study area of the Sinjar District, simulation models used in the study and a research methodology are presented.In chapter 5, The results are presented and discussed for southern and northern of Sinjar Mountain. In chapter 6, Summaries for future study: water harvesting and groundwater recharge, water harvesting and its role in increasing crop productivity and the impact of forecasting on water harvesting. In chapter 7, Summaries for the overall conclusions based on the results and then references of the study are listed.Extended of thesis 1-Water harvesting and reservoir optimization of selected areas south Sinjar Mountain, Iraq, Lulea University of Technology, Sweden.Nadhir Al-Ansari, Mohammad Ezz-Aldeen, Sven Knutsson, Saleh Zakaria Submitted to the Journal of Hydrological Engineering. 2- Rainwater harvesting and supplemental irrigation at northern Sinjar Mountain, Iraq, Lulea University of Technology, Sweden.Saleh Zakaria, Nadhir Al-Ansari, Sven Knutsson, Mohammad Ezz-Aldeen Journal of Purity, Utility Reaction and Environment, Vol. 1 No.3,May 2012, 121-141.

  • 1434.
    Zakaria, Saleh
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Rain Water Harvesting (RWH) North of Iraq2014Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    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.

  • 1435.
    Zakaria, Saleh
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Al-Ansari, Nadhir
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Dawood, Anwer
    Koya University.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Future Prospects for Macro Rainwater Harvesting Technique at Northwest Iraq2014Inngår i: Journal of Earth Sciences and Geotechnical Engineering, ISSN 1792-9040, E-ISSN 1792-9660, Vol. 4, nr 1, s. 1-16Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Rainfall data is part of the main components in the hydrological cycle and firmly associated with almost all aspect of climate. Previous research indicated that Macro rainwater harvesting techniques (RWH) can be implemented successfully in Sinjar area northwest Iraq. Recently, prediction of rainfall trends in the Middle East and Iraq in particular suggest a decrease in rainfall due to climate change. This raises the question about the future validity of RWH in the area.In this research, the validity of RWH was investigated using predicted rainfall data in Sinjar area. Eight seasons were selected representing different decades that start 2020 to 2099. The results showed that the maximum, minimum and average harvested future runoff volumes reached about 28.5, 7.61, and 13.9 million cubic meters, that may occurred during the seasons 2055-2056, 2046-2047, and 2065-2066 respectively. The resultant harvested runoff volumes produced by four selected basins at Eastern Sinjar as a catchment area with total area of 435.15 km2. In the second part, an attempt had been made to provide the study area by a set of charts that can help in estimating daily runoff under dry, wet and normal conditions for rainfall depths that ranged between 15 to 55 mm.

  • 1436.
    Zakaria, Saleh
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Al-Ansari, Nadhir
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Ezz-Aldeen, Mohammad
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Rain water harvesting at eastern Sinjar mountain, Iraq2012Inngår i: Geoscience Research, ISSN 0976-9846, E-ISSN 0976-9854, Vol. 3, nr 2, s. 100-108Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Iraq is facing water shortages and the problem is becoming more serious with time. The main water resources of Iraq (Tigris and Euphrates Rivers) suffer from severe reduction in their discharges due to construction dams on the both banks of Rivers inside Turkey and Syria. Agricultural land had been reduced drastically due to water scarcity. Despite this fact, none of the Iraqi farmers had yet used non-conventional techniques to augment water resources to overcome water shortage problems such as Rainwater Harvesting (RWH) technique.The main aim of this research is to contribute to solving the problem of water shortage of Iraq by finding effective results in terms of saving significant runoff water for irrigation purposes, and therefore provide an academic effort as a tool for encourage and decision support for RWH in Iraq.Macro RWH (large catchment area), was applied at East Sinjar Mountain in Iraq. The estimating volume of harvested runoff ranged (0.11-28.11) ×106 m3 calculated using the Watershed Modeling System (WMS) for the four selected basins together with total area of 435.14 km2 for the study period of (1990-2009).The results of estimating runoff volume showed that the runoff volume can be considered for irrigation practices especially in supplementary irrigation.A linear programming technique was adopted to maximize the irrigated area. Three scenarios of irrigation level were chosen: supplemental irrigation (SI) 100% Satisfy full irrigation requirements (S1), deficit irrigation (DI) 50% of full irrigation requirements (S2), and deficit irrigation (DI) 25% of full irrigation requirements (S3). The resultant irrigated area ranged between 18-2646 for SI 100%, 58-41303 for DI 50%, and 27-9543for DI 25% hectares respectively for all four selected basins together. These results reflect useful value of RWH and its influence to increase the irrigated area in the studied region.

  • 1437.
    Zakaria, Saleh
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Al-Ansari, Nadhir
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Historical and future climatic change scenarios for temperature and rainfall for Iraq2013Inngår i: Journal of Civil Engineering and Architecture, ISSN 1934-7359, E-ISSN 1934-7367, Vol. 7, nr 12, s. 1574-1594Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The world is facing a big challenge of climatic change, mainly due to increasing concentrations of greenhouse gases (GHGs) in the atmosphere. Many researches indicated that the climate change occurred disproportionately on developing countries such as Middle East and North Africa (MENA) countries.The climatic model CGCM3.1 (T47) 2 is used in this research to explain the changes in average temperatures and the rainfall on MMENA region with special emphases on Iraq. Historical records (1900-2009) and future (2020-2099) were studied and compared, each period was divided to four sub-periods of thirty years. The results showed that the average monthly temperature for the four historical periods fluctuated between the lowest and highest value as follows: 9.2-32.9, 10.3-32.7, 9.3-32.8, and 8.6-33.9 (Cº).The rainfall for historical periods kept on the same distribution during the past 109 years, and fluctuated between the lowest and highest value of 21.3 and 37.6 mm with an average that reached up to 26.51 mm. For the future period, the maximum average monthly temperature reached up to 37.41 (Cº) during June and minimum average monthly temperature reached up to 4.24 (Cº) during January. The average monthly temperature fluctuated giving a clear impression that the future portends a higher temperature. The average monthly of rainfall, for the future period, fluctuated between the lowest and highest value of 12.91 and 20.63 mm with an average that reached 16.84 mm which represent a reduction percentage of about 36.47% relative to the historical record of rainfall for the same months.

  • 1438.
    Zakaria, Saleh
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Al-Ansari, Nadhir
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Rainwater harvesting using recorded and hypothetical rainfall data scenarios2013Inngår i: Journal of Earth Sciences and Geotechnical Engineering, ISSN 1792-9040, E-ISSN 1792-9660, Vol. 3, nr 2, s. 21-42Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Macro Rainwater Harvesting (RWH) under recorded and forecasting rainfall scenarios helps to overcome the water shortage problem. Eastern Sinjar District-Iraq had been investigated for the potential of RWH with a catchment area of four basins. Three recorded rainfall scenarios (S1, S2, and S3) were diagnosed representing seasons of the maximum, minimum and average weekly rainfall events for the period 1990-2011. Forecasting the rainfall depths for the same catchment area were estimated depending on Box-Jenkins methodology to build Autoregressive Integrated Moving Average (ARIMA) models for weekly rainfall data for the period 2012-2016. Three forecasting rainfall scenarios (S4, S5, and S6) were diagnosed to represent the seasons of the maximum, minimum and average weekly forecasting rainfall events. The results of these scenarios were compared with an average area to be irrigated obtained from the results of 19 years record. The results indicated that in wet years RWH technique with supplemental irrigation help to give total irrigated area larger than a total specified average irrigated area. In average and dry years, the amounts of the additional needed water were estimated to irrigate the total areas that should be increase in order to satisfy the specified average irrigated area.

  • 1439.
    Zakaria, Saleh
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Al-Ansari, Nadhir
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Wheat yield scenarios for rainwater harvesting at northern Sinjar mountain, Iraq2013Inngår i: Journal of Natural Science, ISSN 0075-4307, Vol. 5, nr 10, s. 1057-1068Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Iraq is part of West Asia and North Africa (WANA) region. The area is known as dry land, famous with gap of crop yield as a result of the water shortage problem.Six basins with total catchment area of 614.19 km2 at rain-fed of Northern Sinjar District-Iraq had been chosen to investigate both of the potential of rainwater harvesting (RWH) and three supplemental irrigation (SI) scenarios S1, S2, and S3 (100%, 75%, and 50% of full irrigation requirement) to support the wheat yield (bread and durum) under various rainfall conditions for the study period 1990-2009.The results indicated that, the total volume of harvested runoff can be considered for irriga- tion practices, that reached up to 42.4 , 25.1, 0.6, 10.9 (*106 m3) during 1995-1996, 1996-1997, 1998-1999, and 2001-2002, respectively.The total irrigated area ranged between 10.9-5163.7 and 8.8-3595.7 (ha) for bread and durum wheat crop for the four selected seasons respectively. The yield scenarios for supplemental irrigation condition Y1, Y2, and Y3 give 68–9712, 94–12999, and 105–22806 Ton for bread wheat, and for durum wheat give 56–8035, 87–10906, and 103–17396 Ton.

  • 1440.
    Zakaria, Saleh
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Al-Ansari, Nadhir
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Al-Badrany, Thafer
    University of Mosul.
    ARIMA Models for weekly rainfall in the semi-arid Sinjar District at Iraq2012Inngår i: Journal of Earth Sciences and Geotechnical Engineering, ISSN 1792-9040, E-ISSN 1792-9660, Vol. 2, nr 3Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Time series analysis and forecasting is an important tool which can be used to improve water resources management. Iraq is facing a severe water shortage problem. The use of rainwater harvesting is one of the techniques to overcome this problem. To put this into practice, it is of prime importance to forecast future rainfall events on a weekly basis.Box-Jenkins methodology has been used in this research to build Autoregressive Integrated Moving Average (ARIMA) models for weekly rainfall data from four rainfall stations in the North West of Iraq: Sinjar, Mosul, Rabeaa and Talafar for the period 1990-2011. Four ARIMA models were developed for the above stations as follow: (3,0,2)x(2,1,1)30, (1,0,1)x(1,1,3)30, (1,1,2)x(3,0,1)30 and (1,1,1)x(0,0,1)30 respectively. The performance of the resulting successful ARIMA models were evaluated using the data year (2011).These models were used to forecast the weekly rainfall data for the up-coming years (2012 to 2016). The results supported previous work that had been carried out on the same area recommending the use of water harvesting in agricultural practices.

  • 1441.
    Zakaria, Saleh
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Al-Ansari, Nadhir
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Ezz-Aldeen, Mohammad
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Rain water harvesting and supplemental irrigation at northern Sinjar mountain, Iraq2012Inngår i: Journal of Purity, Utility Reaction and Environment, ISSN 2232-1179, Vol. 1, nr 3, s. 121-141Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Iraq is facing water shortages and the problem is becoming more serious with time. Despite this fact, none of the farmers had used Rainwater Harvesting (RWH) technique yet. The main aim of this research is to contribute to solving the problem of water shortage of Iraq by finding effective results in terms of saving significant runoff water for irrigation purposes. Macro RWH was applied at Northern Sinjar Mountain in Iraq, where macro is indicator for large catchment area. Runoff volume was determined by applying the watershed modeling system (WMS) for six selected basins with total area of 614.19km2 for the study period of (1990-2009). The volume of harvested water ranged (0.6-42.4) × 106 m3 for all six basins together for the study period. A linear programming technique was adopted to optimize the irrigated area for three scenarios of irrigation, 1/ supplemental irrigation (SI) 100%, 2/ deficit irrigation (DI) 50%, 3/ deficit irrigation (DI) 25% of full irrigation requirements. The results of calculation of irrigated area ranged between 14.5-3663.7 for SI 100%, 33.0-39827.1 for DI 50%, and 20.1-7314.0 for DI 25% hectares respectively. These results reflect useful value of RWH and its influence to increase the irrigated area in the studied region.

  • 1442.
    Zakaria, Saleh
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Al-Ansari, Nadhir
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Mustafa, Yaseen
    Zakho University.
    Alshibli, Mohammad
    Ministry of Water Resources.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Macro rain water harvesting network to estimate annual runoff at Koysinjaq (Koya) district, Kurdistan region of Iraq2013Inngår i: Engineering, ISSN 1947-3931, E-ISSN 1947-394X, Vol. 5, nr 12, s. 956-966Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Macro rainwater harvesting techniques (Macro RWH) are getting more popular to overcome the problem of water scar-city in arid and semi-arid areas. Iraq is experiencing serious water shortage problem now despite the presence of Tigris and Euphrates Rivers. RWH can help to overcome this problem. In this research RWH was applied on Koya city in its districts, North West Iraq. Twenty two basins were identified as the catchment area for the application of RWH tech-nique. Watershed modeling system (WMS), based on Soil Conservation Service - curve number (SCS-CN) method, was applied to calculate direct runoff from individual daily rain storm using average annual rainfall records of the area. Two consecutive adjustments for the curve number were considered. The first was for the antecedent moisture condition (AMC) and the second was for the slope. These adjustments increased the total resultant harvested runoff up to 79.402 *106 m3. The average percentage of increase of harvested runoff volume reached 9.28%. This implies that water allocation is of the order of 2000 cubic meter per capita per year. This quantity of water will definitely help to develop the area.

  • 1443.
    Zakaria, Saleh
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Al-Ansari, Nadhir
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Mustafa, Yaseen
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Ahmed, Payman
    Ghafour, Bahra
    Rainwater harvesting at Koysinjaq (Koya), Kurdistan region, Iraq2013Inngår i: Journal of Earth Sciences and Geotechnical Engineering, ISSN 1792-9040, E-ISSN 1792-9660, Vol. 3, nr 4, s. 25-46Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Macro Rainwater Harvesting (RWH) has been tested at Koysinjaq (Koya) District, Kurdistan region of Iraq, due to its limited source of water.The studied area consists of four basins with total area of 228.96 km2. The estimating volumes of harvested runoff for the four selected basins together for the study period (2002-2011) were calculated using the Watershed Modeling System (WMS) which is based on Soil Conservation Service Curve Number (SCS-CN) method.In this research, a comparison between maximum and minimum rainfall seasons was conducted to give better understanding for the events that is governing the harvested runoff collection.The results show that, the total harvested runoff ranged from14.83 to 80.77(*106 m3) from the four selected basins together. This indicates that the technique of Macro RWH can be considered to provide a new source of water to contribute to reduce the problem of water scarcity.

  • 1444.
    Zakaria, Saleh
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Mustafa, Yassen
    Zakho University.
    Mohammed, Diary
    Sulaimaniya University.
    Ali, Salahalddin
    Sulaimaniya University.
    Al-Ansari, Nadhir
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Estimation of annual harvested runoff at Sulaymaniyah Governorate, Kurdistan region of Iraq2013Inngår i: Journal of Natural Science, ISSN 0075-4307, Vol. 5, nr 12, s. 1272-1283Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Kurdistan Region (KR) of Iraq has suffered from the drought period during the seasons 2007- 2008 and 2008-2009 that affected the human and economic activities of the region. Macro rain- water harvesting (Macro RWH) is one of the te- chniques that can ensure water availability for a region having limited water resources. This te- chnique is based on Soil Conservation Service- Curve Number (SCS-CN) method and the Water- shed Modeling System (WMS) was used to esti- mate the runoff. Rainfall records of Sulaymani- yah area for the period 2002-2012 were studied and an average season was selected (2010-2011). The results of the application of the WMS model showed that about 10.76 million cubic meters could be harvested. The results also showed that the quantity of the harvested runoff was highly affected by rainfall depth, curve number values, antecedent moisture conditions (AMC) and the area of the basins.

  • 1445. Zang, A.
    et al.
    Stephansson, Ove
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik (flyttat 20130630). GFZ German Research Centre for Geosciences, Telegrafenberg, Germany .
    Stress field of the earth's crust2010Bok (Fagfellevurdert)
    Abstract [en]

    This book about rock stress is suitable for students in geosciences and rock engineering, who need to broaden their horizons about the Stress Field of the Earth?s Crust. The book covers the topic so that geosciences students will be able to grasp the Cauchy Stress Principle without fear of matrix transformations in an exercise. Students interested in mathematics, physics and engineering will learn how strain gauges are used to obtain in-situ stress by the overcoring method. Leading edge technology in determining rock stress like quadruple packer and the Kaiser effect are presented together with classical methods like hydraulic fracturing. Borehole techniques (breakouts) and core-based methods (anelastic strain recovery) are illustrated. With respect to stress data, we choose to present the scientific ultra-deep drilling project KTB (Germany), the excavation for nuclear waste disposal at Olkiluoto (Finland) and the drilling into a seismic active fault zone at SAFOD (USA). Stress compilations viewed by the World Stress Map project are presented and interpreted in terms of plate tectonics.

  • 1446.
    Zardari, Muhammad Auchar
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Mechanical properties of fine grained, sulphur rich, silty soils2010Rapport (Annet vitenskapelig)
    Abstract [en]

    Tailings are the waste products produced during extraction of minerals from the ore. The particle size of tailings varies from medium sand to silt or clay size. Tailings are used as a construction material for raising of embankments called tailings dams. During spigotting, the coarse particles (sands) lie close to the embankment, while the fine particles (slimes) move downwards to the impoundment. The rate of failure in tailings dams is higher than that for the conventional water dams. In the past, tailings dams have failed due to various causes such as meteorological incidents, slope instability, piping/seepage, weak foundations, and seismic liquefaction etc. The statistics shows that the tailings dams are not safe even in their construction stages. The closure and reclamation measures require that the tailings dams and impoundments should be stable for a long time (more than 1000 years). Hence, the proper understanding of the mechanical properties (i.e., permeability, stiffness and strength) of tailings is essential in order to make reliable predictions for the long time stability of tailings dams and impoundments. The purpose of the literature survey carried out is: (a) to understand the mechanical properties of tailings material regarding anisotropy, cyclic loading, particle crushing and creep effects; (b) to know the current design practice and identify the factors that may have strong influence on the long time stability of tailings dams and impoundments, and (c) to find from literature, an appropriate constitutive model that can predict realistic behaviour of tailings material. There is similarity in properties of coarse tailings and loose to medium dense natural sands. Slimes are complex material and may show resemblance to natural sands, clays, or a combination of both. The hydraulic conductivity of tailings varies from point to point in a deposit. Tailings are more compressible than the natural soils. The coefficient of consolidation of slimes is in the range shown by natural clays. Due to high particle angularity, the sands and slimes show higher drained shear strength than that for similar natural soils. Undrained strength of sands is important in evaluation of liquefaction behaviour. The embankments can be raised with upstream, downstream or centreline construction methods. The upstream method is susceptible to liquefaction, whereas the downstream and centreline methods are relatively seismic resistant. The stability of the tailings embankments can be enhanced by keeping the phreatic surface low within the embankment body. The phreatic surface can be lowered with the application of cores, drainage zones, and the use of sand tailings in the embankment construction. Cut-off trenches, slurry walls, grout curtains, and liners can control seepage in tailings dams.The pore water pressures develop during construction of tailings embankments. These pore pressures are described as initial static pore pressure, initial excess pore pressure, and pore pressure due to shearing. The stability analyses conditions for conventional water dams (such as end of construction, staged construction, and long term) are also applicable to the tailings dams. The end of construction condition, and staged construction condition of a tailings dam can be analysed with undrained strength analysis. The drained analysis can be used for the long-term condition of a tailings dam (when an embankment attains maximum height and is constructed slowly). The aim of reclamation measures for tailings dams and impoundments is to achieve long time mass stability, environmental safety, and productive land use. Tailings impoundments can be stabilized with ripraps, chemicals, vegetation, and dry/wet covers etc.Most natural soils show anisotropy in strength due to their depositional history. Due to low density and high degree of saturation, tailings show large cyclic strains in a few cycles of stress reversal. The cyclic strength of tailings can increase with decreasing void ratio. Creep occurs in all soils. Clays show more creep than sands. Loose sands creep more than dense sands. The loads due to high tailings embankments may cause particle crushing and creep. The long time stability of tailings dams and impoundments can be predicted with finite element analysis with suitable constitutive models. The numerical analysis needs to be carried out for severe conditions of rainfalls, floods, and earthquakes.

  • 1447.
    Zardari, Muhammad Auchar
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Numerical analyses of stability of a gradually raised tailings dam2013Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Numerical analyses are presented in this thesis to address potential stability problems that may occur during gradual raisings and under seismic loading conditions of Aitik tailings dam in northern Sweden. The dam is mainly raised using upstream construction method. It is planned to raise the dam gradually in several stages. Two dam parts were studied. The first dam part is a straight dam portion, and the second dam part is a corner. The main concerns associated with future raisings of the straight dam part were: (i) the stability of the dam could be affected by an increase in excess pore pressures during sequential raisings, (ii) how to gradually strengthen the dam by using rockfill berms as supports in such a way that required slope stability can be achieved with a minimum volume of rockfill berms, and (iii) if the dam is subjected to seismic loading, whether or not an increase in excess pore pressures could lead to extensive liquefaction which may cause a failure. The problems related to the dam corner were that tension zones and/or low compression zones could develop because of the horizontal pressure of the stored tailings on the inside of the curvature of the dam corner.Numerical analyses were conducted on both the dam parts using finite element method. Two dimensional (2D) plane strain finite element model was utilized to analyse the straight dam. The dam corner was analysed with both the three dimensional (3D) finite element model, and the 2D axisymmetric finite element model. Coupled deformation and consolidation analyses, and slope stability analyses were performed on both the dam parts to simulate gradual raisings, and to compute safety factors. In addition to this, dynamic analyses were carried out on the straight dam part to evaluate the potential for liquefaction, and seismic stability of the dam. The seismic behaviour of the dam was analysed for two cases: (i) a normal case (earthquake of 3.6 Swedish local magnitude), and (ii) an extreme case (earthquake of 5.8 moment magnitude).The results of the straight dam part, with only previously existing rockfill berms, indicate that stability of the dam was reduced due to an increase in excess pore pressures during raisings. Rockfill berms were utilized as supports to raise the dam with enough safety. An optimization technique was utilized to minimize the volume of rockfill berms. This technique could result in significant saving of cost of rockfill berms.The results of the dam corner show that tension zones and/or low compression zones were located on the surface of the dam corner, mainly above the phreatic level. It is interpreted that there is no risk of internal erosion through the embankments because no seepage path occurs above the phreatic level, and a filter zone exists along the slope of the dam. It is suggested to gradually strengthen the dam corner with rockfill berms. The results of the 2D axisymmetric analyses of the dam corner were in a fairly good agreement with those of the 3D analyses. This implies that the 2D axisymmetric analyses are valid for this dam corner. This is an important finding as 2D axisymmetric analyses require much less computational time compared to 3D analyses.The results of the dynamic analyses performed on the straight dam (including additional rockfill berms) suggest that, for the extreme case, liquefaction could occur in a limited zone that is located below the surface near the embankments. For both the normal and the extreme case, (i) seismically induced displacements seem to be tolerable, and (ii) the post seismic stability of the dam is considered to be sufficient.The findings of this study have been practically applied to the Aitik tailings dam. In general, the modelling procedure and the optimization technique to minimize volume of rockfill berms, presented in this study, could be applied to other tailings dams.

  • 1448.
    Zardari, Muhammad Auchar
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Stability of tailings dams: focus on numerical modelling2011Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Upstream tailings dams may experience slope stability problems when the rate of raising is too fast. Tailings consolidate slowly due to low hydraulic conductivity. The excess pore pressures can build up due to accelerated rate of raising. The cumulative increase in excess pore pressures due to successive raisings can endanger slope stability of a tailings dam. The stability of a tailings dam is closely related to the consolidation process. The consolidation process and associated stability of an upstream tailings dam during staged construction was modelled with the finite element program PLAXIS. The analysis indicated that the stability of the dam reduced during raising due to increase of excess pore pressures. The safety of the dam was improved by adding rockfill banks on the downstream side. The volume of the rockfill banks was minimized with an optimization technique. This technique involves (i) construction of a rockfill bank on the downstream side when the factor of safety is less than a permissible limit, (ii) utilization of a minimum volume of the rockfill that is necessary to stabilize the slope. This technique can be practicable when the rate of raising is moderate, and partial consolidation occurs between consecutive raisings. Numerical analysis was also performed on a curved embankment of an upstream tailings dam in order to investigate the possible risk of hydraulic fracturing and internal erosion in a corner of the dam. The analysis showed that low compressive stresses occurred above the phreatic level, near the zones of filter and rockfill banks. These zones contain coarse material, and are, therefore, not susceptible to hydraulic fracturing and internal erosion. An increase in the radius of the corner is suggested in order to prevent large reductions in compressive stresses that may occur due to future raisings. Presently the curved dam section is stable. However, an additional rockfill bank on the downstream side will be required for future raisings. Static liquefaction is considered as a common cause of disastrous flow failures of tailings dams. These flow failures can be predicted with numerical modelling using suitable constitutive models. In this context, some constitutive models capable of simulating static liquefaction behaviour of loose saturated sands are reviewed. It is generally concluded that the finite element method can be a helpful tool for modelling stability of tailings dams.

  • 1449.
    Zardari, Muhammad Auchar
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Mattsson, Hans
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    3D finite element analyses of a corner at Aitik tailings dam in Sweden2012Inngår i: SWEMP 2012: International symposium on Environmental Issues and Waste Management in Energy and Mineral Production, 2012, s. 444-452Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The 3D finite element analyses were performed for the gradual raisings of a corner section of Aitik tailings dam, located in the north of Sweden. The purpose of the analyses was to investigate the potential risk of low compressive stresses or tensile stresses in the corner and to evaluate the slope stability of the dam for current and future raisings. The results indicate that the magnitudes of the minor effective principal stresses in the interior of the dam are sufficient to resist the development of soft zones or cracks in the dam and it is interpreted that there is no increased risk of internal erosion. The slope stability analyses show that the dam has enough safety up to a height of 76 m, if the dam is gradually strengthened with rockfill supports on the downstream side.

  • 1450.
    Zardari, Muhammad Auchar
    et al.
    Quaid-e-AwamUniversity of Engineering, Science and Technology, Nawabshah.
    Mattsson, Hans
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Ormann, Linda
    Fortum, Power Division, Renewable Energy, Våxnäsgatan 10, Box 2087, SE-65002 Karlstad, 8 Sweden.
    Comparison of three-dimensional and two-dimensional axisymmetric finite element analyses of a corner section of a tailings dam2017Inngår i: Scientia Iranica. International Journal of Science and Technology, ISSN 1026-3098, E-ISSN 2345-3605, Vol. 24, nr 5, s. 2320-2331, artikkel-id 9Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper presents three dimensional (3D) and two dimensional (2D) axisymmetric finite element analyses of a corner of a tailings dam. The analyses were performed to: (i) locate tension and/or low compression zones and to evaluate slope stability during sequential raising of the dam corner, and (ii) find whether the results of 2D axisymmetric analyses can be reliable for the dam corner. The corner is a potentially weak section of the dam where tension and/or low compression zones may develop. Development of such zones inside the dam corner can lead to cracks and initiation of internal erosion. The results of both the 3D and 2D axisymmetric analyses indicated that (i) tension and/or low compression zones were located in vicinity of surface of the dam corner mainly above the phreatic level, and (ii) the dam corner is stable up to the planned height if it is gradually strengthened with rockfill berms on the downstream side. The results of 2D axisymmetric analyses showed a fairly good agreement with those of 3D analyses. It is concluded that 2D axisymmetric analyses are appropriate for this dam corner. This implies that significant computational time can be saved by utilizing 2D analyses instead of 3D analyses.

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