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  • 1.
    Acuña, José
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Distributed thermal response tests: New insights on U-pipe and Coaxial heat exchangers in groundwater-filled boreholes2013Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    U-pipe Borehole Heat Exchangers (BHE) are widely used today in ground source heating and cooling systems in spite of their less than optimal performance. This thesis provides a better understanding on the function of U-pipe BHEs and Investigates alternative methods to reduce the temperature difference between the circulating fluid and the borehole wall, including one thermosyphon and three different types of coaxial BHEs.

    Field tests are performed using distributed temperature measurements along U-pipe and coaxial heat exchangers installed in groundwater filled boreholes. The measurements are carried out during heat injection thermal response tests and during short heat extraction periods using heat pumps. Temperatures are measured inside the secondary fluid path, in the groundwater, and at the borehole wall. These type of temperature measurements were until now missing.

    A new method for testing borehole heat exchangers, Distributed Thermal Response Test (DTRT), has been proposed and demonstrated in U-pipe, pipe-in-pipe, and multi-pipe BHE designs. The method allows the quantification of the BHE performance at a local level.

    The operation of a U-pipe thermosyphon BHE consisting of an insulated down-comer and a larger riser pipe using CO2 as a secondary fluid has been demonstrated in a groundwater filled borehole, 70 m deep. It was found that the CO2 may be sub-cooled at the bottom and that it flows upwards through the riser in liquid state until about 30 m depth, where it starts to evaporate.

    Various power levels and different volumetric flow rates have been imposed to the tested BHEs and used to calculate local ground thermal conductivities and thermal resistances. The local ground thermal conductivities, preferably evaluated at thermal recovery conditions during DTRTs, were found to vary with depth. Local and effective borehole thermal resistances in most heat exchangers have been calculated, and their differences have been discussed in an effort to suggest better methods for interpretation of data from field tests.

    Large thermal shunt flow between down- and up-going flow channels was identified in all heat exchanger types, particularly at low volumetric flow rates, except in a multi-pipe BHE having an insulated central pipe where the thermal contact between down- and up-coming fluid was almost eliminated.

    At relatively high volumetric flow rates, U-pipe BHEs show a nearly even distribution of the heat transfer between the ground and the secondary fluid along the depth. The same applies to all coaxial BHEs as long as the flow travels downwards through the central pipe. In the opposite flow direction, an uneven power distribution was measured in multi-chamber and multi-pipe BHEs.

    Pipe-in-pipe and multi-pipe coaxial heat exchangers show significantly lower local borehole resistances than U-pipes, ranging in average between 0.015 and 0.040 Km/W. These heat exchangers can significantly decrease the temperature difference between the secondary fluid and the ground and may allow the use of plain water as secondary fluid, an alternative to typical antifreeze aqueous solutions. The latter was demonstrated in a pipe-in-pipe BHE having an effective resistance of about 0.030 Km/W.

    Forced convection in the groundwater achieved by injecting nitrogen bubbles was found to reduce the local thermal resistance in U-pipe BHEs by about 30% during heat injection conditions. The temperatures inside the groundwater are homogenized while injecting the N2, and no radial temperature gradients are then identified. The fluid to groundwater thermal resistance during forced convection was measured to be 0.036 Km/W. This resistance varied between this value and 0.072 Km/W during natural convection conditions in the groundwater, being highest during heat pump operation at temperatures close to the water density maximum.

  • 2. Al-Yaarubi, A. H.
    et al.
    Pain, C. C.
    Grattoni, C. A.
    Zimmerman, Robert W.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Mark- och vattenteknik.
    Navier-Stokes Simulations of Fluid Flow Through a Rock Fracture2013Ingår i: Dynamic Fluids and Transport Through in Fractured Rock, American Geophysical Union (AGU), 2013, s. 55-64Kapitel i bok, del av antologi (Övrigt vetenskapligt)
    Abstract [en]

    A surface profilometer was used to measure fracture profiles every 10 microns over the surfaces of a replica of a fracture in a red Permian sandstone, to within an accuracy of a few microns. These surface data were used as input to two finite element codes that solve the Navier-Stokes equations and the Reynolds equation, respectively. Numerical simulations of flow through these measured aperture fields were carried out at different values of the mean aperture, corresponding to different values of the relative roughness. Flow experiments were also conducted in casts of two regions of the fracture. At low Reynolds numbers, the Navier-Stokes simulations yielded transmissivities for the two fracture regions that were closer to the experimental values than were the values predicted by the lubrication model. In general, the lubrication model overestimated the transmissivity by an amount that varied as a function of the relative roughness, defined as the standard deviation of the aperture divided by the mean aperture. The initial deviations from linearity, for Reynolds numbers in the range 1-10, were consistent with the "weak inertia" model developed by Mei and Auriault for porous media, and with the results obtained computationally by Skjetne et al in 1999 on a two-dimensional self-affine fracture. In the regime 10 < Re < 40, both the computed and measured transmissivities could be fit very well to a Forchheimer-type equation, in which the additional pressure drop varies quadratically with the Reynolds number.

  • 3.
    Andersson, Johan Vium
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE).
    Undifferenced GPS for Deformation Monitoring2006Licentiatavhandling, monografi (Övrigt vetenskapligt)
    Abstract [en]

    This thesis contains the development of a deformation monitoring software based on undifferenced GPS observations. Software like this can be used in alarm systems placed in areas where the earth is unstable. Systems like this can be used in areas where people are in risk of getting hurt, like in earthquake zones or in land slide areas, but they can also be useful when monitoring the movements in buildings, bridges and other artefacts.

    The main hypotheses that are tested are whether it is possible to detect deformations with undifferenced observations and if it is possible to reach the same accuracy in this mode as when working in a traditional mode where the observations are differenced.

    The development of a deformation monitoring software based on undifferenced GPS observations is presented. A complete mathematical model is given as well as implementation details. The software is developed in Matlab together with a GPS observation simulator. The simulator is mainly used for debugging purposes.

    The developed software is tested with both simulated and real observations. Results from tests with simulated observations show that it is possible to detect deformations in the order of a few millimetres with the software. Calculations with real observations give the same results. Further, the result from calculations in static mode indicates that the commercial software and the undifferenced software diverge a few millimetres, which probably depends on different implementations of the tropospheric corrections. In kinematic mode the standard deviation is about 1 millimetre larger in the undifferenced mode than in the double differenced mode. An initial test with different observation weighting procedures indicates that there is a lot of potential to improve the result by applying correct weights to the observations. This is one of the aims in the future work within this project.

    This thesis are sponsored by the Swedish Research Council for Enviroment, Agricultural Sciences and Spatial Planning, FORMAS within the framework “Monitoring of construction and detection of movements by GPS ref no. 2002-1257"

  • 4.
    Bjureland, William
    Mälardalens högskola, Akademin för hållbar samhälls- och teknikutveckling.
    Uttorkning av lera: Orsaker och följder2010Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
  • 5.
    Bjureland, William
    Mälardalens högskola, Akademin för hållbar samhälls- och teknikutveckling.
    Uttorkning av lera: Orsaker och följder2010Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

    When building a house or similar the stress on the ground increases and deformations can arise. The deformations create a foundation that the building is not constructed for and damages on the building arise. The increased stress on the ground can be derived back to the building, but it is possible that the increased stress may well derive from different sources such as other buildings or trees.      

     

    The building is an older property, built in the late 19th century alternatively early 20th century, and is today used for rental housing and has suffered severe damages due to subsidence. The goal of the thesis is to find possible causes for these subsidences.

     

    The thesis was executed as a combination between literature- and casestudie.

     

    After careful studies it has been found that a probable cause for these subsidences is trees. Through field- and lab studies it has been found that the trees has effected the ground through there accumulation of water. This has caused the soil to dry up and subsidence’s has probably arisen through the decrease in pore pressure due to the disappearing of water. This, however, needs to be proven by further studies of pore pressures in the area.

  • 6. Boano, F.
    et al.
    Harvey, J. W.
    Marion, A.
    Packman, A. I.
    Revelli, R.
    Ridolfi, L.
    Wörman, Anders
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Vattendragsteknik.
    Hyporheic flow and transport processes: Mechanisms, models, and biogeochemical implications2014Ingår i: Reviews of geophysics, ISSN 8755-1209, E-ISSN 1944-9208, Vol. 52, nr 4, s. 603-679Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    Fifty years of hyporheic zone research have shown the important role played by the hyporheic zone as an interface between groundwater and surface waters. However, it is only in the last two decades that what began as an empirical science has become a mechanistic science devoted to modeling studies of the complex fluid dynamical and biogeochemical mechanisms occurring in the hyporheic zone. These efforts have led to the picture of surface-subsurface water interactions as regulators of the form and function of fluvial ecosystems. Rather than being isolated systems, surface water bodies continuously interact with the subsurface. Exploration of hyporheic zone processes has led to a new appreciation of their wide reaching consequences for water quality and stream ecology. Modern research aims toward a unified approach, in which processes occurring in the hyporheic zone are key elements for the appreciation, management, and restoration of the whole river environment. In this unifying context, this review summarizes results from modeling studies and field observations about flow and transport processes in the hyporheic zone and describes the theories proposed in hydrology and fluid dynamics developed to quantitatively model and predict the hyporheic transport of water, heat, and dissolved and suspended compounds from sediment grain scale up to the watershed scale. The implications of these processes for stream biogeochemistry and ecology are also discussed.

  • 7.
    Breton, Simon-Philippe
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper.
    Shen, W.Z.
    Technical University of Denmark, Energivej, Building 414, 2800 Kgs. Lyngby, Denmark.
    Ivanell, Stefan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper.
    Validation of the actuator disc and actuator line techniques for yawed rotor flows using the New MEXICO experimental data2017Konferensbidrag (Refereegranskat)
    Abstract [en]

    Experimental data acquired in the New MEXICO experiment on a yawed 4.5m diameter rotor model turbine are used here to validate the actuator line (AL) and actuator disc (AD) models implemented in the Large Eddy Simulation code EllipSys3D in terms of loadingand velocity field. Even without modelling the geometry of the hub and nacelle, the AL and AD models produce similar results that are generally in good agreement with the experimental data under the various configurations considered. As expected, the AL model does better at capturing the induction effects from the individual blade tip vortices, while the AD model can reproduce the averaged features of the flow. The importance of using high quality airfoil data (including 3D corrections) as well as a fine grid resolution is highlighted by the results obtained. Overall, it is found that both models can satisfactorily predict the 3D velocity field and blade loading of the New MEXICO rotor under yawed inflow.

  • 8.
    Bäckström, Ann
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik.
    A study of impact fracturing and electric resistivity related to the Lockne impact structure, Sweden2005Ingår i: Impact Tectonics / [ed] Koeberl C; Henkel H, 2005, s. 389-404Konferensbidrag (Refereegranskat)
    Abstract [en]

    The fracture frequency and the electric resistivity of outcrops of crystalline basement rocks at the Lockne meteorite impact site have been studied in order to investigate the extent and radial changes of impact induced fracturing. By measuring the electric resistivity and the fracture frequency at the same outcrops, the effect of fracturing on the electric properties of the rock is estimated and correlated with the fracture frequency. A negative linear correlation between the Log of fracture frequency and the Log of electric resistivity was found.

    It was also found that the fracture frequency decreases in a transition zone over a distance of about 1100 m across the southern margin of the impact structure. A similar set of measurements was made across the suggested northern limit of the structure, but no change was detected. This implies that the outer limit of the Tandsbyn Breccia is further to the north. The studied area is, therefore, not likely to be the. margin of the structure.

  • 9.
    Bäckström, Ann
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Teknisk geologi och geofysik.
    Rock damage caused by underground excavation and meteorite impacts2008Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The intent of this thesis is to contribute to the understanding of the origin of fractures in rock. The man-made fracturing from engineering activities in crystalline rock as well as the fracturing induced by the natural process of meteorite impacts is studied by means of various characterization methods. In contrast to engineering induced rock fracturing, where the goal usually is to minimize rock damage, meteorite impacts cause abundant fracturing in the surrounding bedrock. In a rock mass the interactions of fractures on the microscopic scale (mm-cm scale) influence fractures on the mesoscopic scale (dm-m scale) as well as the interaction of the mesocopic fractures influencing fractures on the macroscopic scale (m-km scale). Thus, among several methods used on different scales, two characterization tools have been developed further. This investigation ranges from the investigation of micro-fracturing in ultra-brittle rock on laboratory scale to the remote sensing of fractures in large scale structures, such as meteorite impacts. On the microscopic scale, the role of fractures pre-existing to the laboratory testing is observed to affect the development of new fractures. On the mesoscopic scale, the evaluation of the geometric information from 3D-laser scanning has been further developed for the characterisation of fractures from tunnelling and to evaluate the efficiency of the tunnel blasting technique in crystalline rock. By combining information on: i) the overbreak and underbreak; ii) the orientation and visibility of blasting drillholes and; iii) the natural and blasting fractures in three dimensions; a analysis of the rock mass can be made. This analysis of the rock mass is much deeper than usually obtained in rock engineering for site characterization in relation to the blasting technique can be obtained based on the new data acquisition. Finally, the estimation of fracturing in and around two meteorite impact structures has been used to reach a deeper understanding of the relation between fracture, their water content and the electric properties of the rock mass. A correlation between electric resistivity and fracture frequency in highly fractured crystalline rock has been developed and applied to potential impact crater structures. The results presented in this thesis enables more accurate modelling of rock fractures, both supporting rock engineering design and interpretation of meteorite impact phenomena.

  • 10.
    Bäckström, Ann
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Teknisk geologi och geofysik.
    Cosgrove, John W.
    Department of Earth Science and Engineering, Imperial College, London.
    Hudson, John A.
    Department of Earth Science and Engineering, Imperial College, London.
    Interpretation of the development of induced cracks within a pre-cracked rock microstructure and the similarities with the geometry of larger-scale geological fracturesIngår i: Journal of Structural Geology, ISSN 0191-8141, E-ISSN 1873-1201Artikel i tidskrift (Övrigt vetenskapligt)
  • 11.
    Bäckström, Ann
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Teknisk geologi och geofysik.
    Feng, Quanhong
    Berg Bygg Konsult AB.
    Lanaro, Flavio
    Berg Bygg Konsult AB.
    Excavation Damage Zone (EDZ) at the TASQ tunnel (Äspö, Sweden): Quantification of blasting effects on the geological settings by 3D-laser-scanningIngår i: Engineering Geology, ISSN 0013-7952, E-ISSN 1872-6917Artikel i tidskrift (Övrigt vetenskapligt)
  • 12.
    Bäckström, Ann
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Teknisk geologi och geofysik.
    Feng, Quanhong
    Berg Bygg Konsult AB.
    Lanaro, Flavio
    Berg Bygg Konsult AB.
    Christiansson, Rolf
    Swedish Nuclear Fuel and Waste Management Co.
    Evaluation of the Excavation Damage Zone (EDZ) by using 3-D laser scanning technique2006Ingår i: The 4th Asian Rock Mechanics Symposium, Singapore, 8 - 10 November 2006, 2006Konferensbidrag (Övrigt vetenskapligt)
  • 13.
    Bäckström, Ann
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Teknisk geologi och geofysik.
    Jing, Lanru
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Teknisk geologi och geofysik.
    Koyama, Tomofumi
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Teknisk geologi och geofysik.
    et al.,
    Numerical modelling of uniaxial compressive failure of granite with and without saline porewater2008Ingår i: International Journal of Rock Mechanics And Mining Sciences, ISSN 1365-1609, E-ISSN 1873-4545, Vol. 45, nr 7, s. 1126-1142Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    It is important for rock engineering design to be able to validate numerical simulations, i.e. to check that they adequately represent the rock reality. In this paper, the capability and validity of four numerical models is assessed through the simulation of an apparently simple case: the complete process of microstructural breakdown during the uniaxial compressive failure of intact crystalline rock. In addition to comparing the capabilities of the four models, the results generated by each model were compared with the experimentally determined complete stress-strain curves for the Swedish Avro granite for different porewater conditions. In this way, it has been possible to audit the models' adequacy for this particular simulation task. It was found that although the models had common features, they were each idiosyncratically different and required considerable expertise to match the actual stress-strain curves (which did not monotonically increase in axial strain)-indicating that, for more complex simulations, both adequate modelling and appropriate validation are not going to be an easy task. The work was conducted within the framework of the international 2004-2007 DEmonstration of COupled models and their VALidation against EXperiments with emphasis on Thermo Hydro Mechanic and Chemical aspects (DECOVALEX-THMC) phase on coupled modelling extended to include chemical effects and with application to the excavation damaged zone (EDZ) in crystalline rock.

  • 14. Bäckström, Ann
    et al.
    Lanaro, Flavio
    Berg Bygg Konsult AB.
    Christiansson, Rolf
    Swedish Nuclear Fuel and Waste Management Co.
    Coupled chemical-mechanical behaviour: the influence of salinity on the uniaxial compressive strength of the Smålands granite, Sweden2006Ingår i: Proc. of the 2nd International Conference on Coupled T-H-MC Processes in Geo-Systems: Fundamentals, Modeling, Experiments and Applications, Geo-Proc 2006, 2006, s. 437-443Konferensbidrag (Refereegranskat)
  • 15. Chan, T.
    et al.
    Christiansson, R.
    Boulton, G. S.
    Ericsson, L. O.
    Hartikainen, J.
    Jensen, M. R.
    Ivars, Diego Mas
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik.
    Stanchell, F. W.
    Vistrand, P.
    Wallroth, T.
    DECOVALEX III BMT3/BENCHPAR WP4: The thermo-hydro-mechanical responses to a glacial cycle and their potential implications for deep geological disposal of nuclear fuel waste in a fractured crystalline rock mass2005Ingår i: International Journal of Rock Mechanics And Mining Sciences, ISSN 1365-1609, E-ISSN 1873-4545, Vol. 42, nr 5-6, s. 805-827Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A number of studies related to past and on-going deep repository performance assessments have identified glaciation/ deglaciation as major future events in the next few hundred thousand years capable of causing significant impact on the long term performance of the repository system. Benchmark Test 3 (BMT3) of the international DECOVALEX III project has been designed to provide an illustrative example that explores the mechanical and hydraulic response of a fractured crystalline rock mass to a period of glaciation. The primary purpose of this numerical study is to investigate whether transient events associated with a glacial cycle could significantly influence the performance of a deep geological repository in a crystalline Shield setting. A conceptual site-scale (tens of kilometres) hydro-mechanical (HM) model was assembled based primarily on site-specific litho-structural, hydrogeological and geomechanical data from the Whiteshell Research Area in the Canadian Shield, with simplification and generalization. Continental glaciological modelling of the Laurentide ice sheet through the last glacial cycle lasting approximately 100,000 years suggests that this site was glaciated at about 60 ka and between about 22.5 and 11 ka before present with maximum ice sheet thickness reaching 2500 m and maximum basal water pressure head reaching 2000m. The ice-sheet/drainage model was scaled down to generate spatially and temporally variable hydraulic and mechanical glaciated surface boundary conditions for site-scale subsurface HM modelling and permafrost modelling. Under extreme periglacial conditions permafrost was able to develop down to the assumed 500-m repository horizon. Two- and three-dimensional coupled HM finite-element simulations indicate: during ice-sheet advance there is rapid rise in hydraulic head, high transient hydraulic gradients and high groundwater velocities 2-3 orders of magnitude higher than under nonglacial conditions; surface water recharges deeper than under nonglacial conditions; upon ice-sheet retreat, the gradients reverse; fracture zone network geometry, interconnectivity and hydraulic properties significantly influence flow domain response; residual elevated heads are preserved for 10,000s in the low-diffusivity rock; and no hydraulic jacking or shear failure occurs at depth. It was found that transient coupled modelling is necessary to capture the essence of glacial effects on Performance Assessment. Model dimensionality also significantly affects simulated results.

  • 16.
    Dargahi, Bijan
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Vattendragsteknik.
    Setegn, Shimelis Gebriye
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Vattendragsteknik.
    Combined 3D Hydrodynamic and Watershed Modelling of Lake Tana, Ethiopia2011Ingår i: Journal of Hydrology, ISSN 0022-1694, E-ISSN 1879-2707, Vol. 398, nr 1-2, s. 44-64Artikel i tidskrift (Refereegranskat)
    Abstract [en]

     The growing high demand for lake Tana water portends a disturbing future. The main objective of this paper is to make a contribution to the development of a sustainable use of the water of Lake Tana. A fully three-dimensional hydrodynamic model was combined with a watershed model and together, these models were successfully validated for the year 2006. The flow structure is characterized by large recirculation and secondary flow regions. Secondary flows are induced by hydrodynamic instabilities occurring at the interfaces of layers with a velocity gradient and the interaction with the irregularities of the bed. The weak stratification process in Lake Tana is characterized by a classic summer profile, which is more pronounced during January-February. Mixing processes in the lake are controlled by wind, the mixing energy induced by both river inflows and the lake outlet, and convective mixing due to the negative buoyancy. An alarming fall of the water levels in Lake Tana was found in response to the planned water withdrawal. The long flushing time (19 months) will not allow a fast decay of contaminated materials released into the lake. The flow structure will not be significantly modified by the planned water withdrawal but the flushing time will decrease. The hydrodynamics of Lake Tana resemble a closed system similar to a shallow reservoir with an overflow type outlet. The implication is that the lake is vulnerable to changes in external conditions and sustainable use of the water resource of the lake will require awareness of this vulnerability. The combined watershed and hydrodynamic models would be effective tools to achieve this awareness. It is also necessary to address the impact of climate change on the fate of the lake. These are all difficult challenges that need to be addressed to safeguard the sensitive eco-system of the area.

  • 17.
    Dessirier, Benoît
    et al.
    Stockholms universitet, Institutionen för naturgeografi.
    Frampton, Andrew
    Stockholms universitet, Institutionen för naturgeografi.
    Fransson, A.
    Jarsjö, Jerker
    Stockholms universitet, Institutionen för naturgeografi.
    Modeling early in situ wetting of a compacted bentonite buffer installed in low permeable crystalline bedrock2016Ingår i: Water resources research, ISSN 0043-1397, E-ISSN 1944-7973, Vol. 52, nr 8, s. 6207-6221Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The repository concept for geological disposal of spent nuclear fuel in Sweden and Finland is planned to be constructed in sparsely fractured crystalline bedrock and with an engineered bentonite buffer to embed the waste canisters. An important stage in such a deep repository is the postclosure phase following the deposition and the backfilling operations when the initially unsaturated buffer material gets hydrated by the groundwater delivered by the natural bedrock. We use numerical simulations to interpret observations on buffer wetting gathered during an in situ campaign, the Bentonite Rock Interaction Experiment, in which unsaturated bentonite columns were introduced into deposition holes in the floor of a 417 m deep tunnel at the Aspo Hard Rock Laboratory in Sweden. Our objectives are to assess the performance of state-of-the-art flow models in reproducing the buffer wetting process and to investigate to which extent dependable predictions of buffer wetting times and saturation patterns can be made based on information collected prior to buffer insertion. This would be important for preventing insertion into unsuitable bedrock environments. Field data and modeling results indicate the development of a de-saturated zone in the rock and show that in most cases, the presence or absence of fractures and flow heterogeneity are more important factors for correct wetting predictions than the total inflow. For instance, for an equal open-hole inflow value, homogeneous inflow yields much more rapid buffer wetting than cases where fractures are represented explicitly thus creating heterogeneous inflow distributions.

  • 18.
    Elvin, Lena
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper.
    Dangré, Markus
    Spetsbärförmåga hos betongpålar slagna i friktionsjord2004Självständigt arbete på avancerad nivå (yrkesexamen), 20 poäng / 30 hpStudentuppsats
    Abstract [sv]

    Syftet med examensarbetet är att upprätta en databas över spetsburna pålar fastslagna i friktionsjord och morän. Vidare skall databasen analyseras för att hitta styrande parametrar samt även hitta områden med problematisk geoteknik.

    Databasen omfattar spetsburna pålar som stoppslås i friktionsjord. Pålar som i huvudsak är mantelburna har uteslutits. Endast betongpålar har tagits med. Geografiskt omfattar databasen i stort sett hela Sverige. Totalt innehåller databasen 110 projekt med sammanlagt över 600 pålar.

    För entreprenörer i byggbranschen är grundläggningsarbetet ofta förknippat med ekonomiska risker och osäkerhet gällande omfattning och tidsåtgång. Vid dimensionering av grundläggningsarbeten kan databasen vara till stor hjälp för att bestämma lämpliga lastnivåer. Mängden slagningsarbete och risken för bortslagna pålar kan lättare uppskattas.

    Först analyserades olika påltyper utan ytterligare urvalskriterier. Vikten av att filtrera informationen blev då tydlig, eftersom resultatet blev svårtolkat och inga markanta samband kunde urskiljas. Med databasen som grund har materialet vidare analyserats med hjälp av statistiska metoder. Orsaken till låga bärförmågor vid ett urval av projekt har även kartlagts.

  • 19.
    Farcas, Florentina
    Linköpings universitet, Institutionen för datavetenskap, GIS - Geografiska informationssystem.
    Road Traffic Noise - A study of region Skåne, Sweden2008Självständigt arbete på avancerad nivå (masterexamen), 30 poäng / 45 hpStudentuppsats
    Abstract [en]

    Since the first car appeared, the pollution on the roads became an issue, which is still mainly unsolved. Too many people complain about traffic noise. Various methods have been developed that aimed at minimizing the noise pollution and improving the environment.

    This thesis presents the problems posed by noise pollution, covers the background of noise pollution and its effects on human health. Another important part of the thesis covers the method of noise calculation which applies in specific Nordic countries.

    The main goal of the thesis is to present maps of noise levels on roads for region Skåne in Sweden. Because the regulation and the limits for noise levels are different for different countries, I could find various calculators for traffic noise. Australia, England, USA have the noise level calculators open for public. Another professional calculator, SoundPlan, is a program that can perform a very accurate calculation for traffic noise but only for small areas. Because of this disadvantage, the request for my thesis was to provide a program which can calculate traffic noise level for wide areas. As a master student specialist in GIS (Geographic Information System) it was natural to develop the traffic noise calculator with available GIS tools.

    The software system to calculate the traffic noise maps was implemented in ArcMap 9.1, a GIS program which allows creation of tools, according to a mathematical description of noise calculator. The mathematical description is based on the Nordic Prediction method, a document which set up requirements for prediction of road traffic noise. ArcMap 9.1 allows the development of extensions in different programming languages. The tools implemented in this thesis are written in Visual Basic. The thesis work implements several tools for calculating noise levels, starting from the basic traffic noise level and introducing additional noise corrections to perform more accurate noise calculation. The additional corrections could be added because I had access to additional data regarding buildings and population location. The available population data from Lund gave me the opportunity to create a tool which performs population exposure to noise in this region.

     

  • 20.
    Fernlund, Joanne M. Robison
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Teknisk geologi och geofysik.
    Tafesse, Solomon
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Teknisk geologi och geofysik.
    Magnusson, Mimmi K.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Teknisk geologi och geofysik.
    Total analysis of till using resistivity and 3D image analysisArtikel i tidskrift (Övrigt vetenskapligt)
  • 21.
    Fernlund, Joanne
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Teknisk geologi och geofysik.
    Tafesse, Solomon
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Teknisk geologi och geofysik.
    Magnusson, Mimmi
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Teknisk geologi och geofysik.
    Lithological analysis of multiple size fractions of tillArtikel i tidskrift (Övrigt vetenskapligt)
  • 22.
    Giron, Alexander
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper.
    Effekter på grund- och ytvattenförhållandenkring svenska oljelager i bergrum2015Självständigt arbete på avancerad nivå (yrkesexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Det saknas i dagsläget en samlad redovisning av erfarenheter rörande påverkan pågrundvattennivåer samt ytvattennivåer och flöden vid grundvattenbortledning från Svenskaberganläggningar. Det saknas även en utvärdering av olika prognosmetoders tillämpbarhetbaserad på prognoser kontra utfall.Det finns ett brett spektrum av metoder för att prognostisera effekterna, från relativt enklabedömningar baserat på vattenbalanser, analytiska lösningar, till avancerade numeriskamodelleringsverktyg. Vilken eller vilka metoder som används i det enskilda fallet styrs idealtav faktorer som exempelvis anläggningstyp, hydrogeologiska förhållanden och dekonsekvenser som grundvattenbortledning potentiellt kan ge upphov till i omgivningen. Ensamling av branscherfarenheter skulle således kunna leda till en effektivisering samt enkostnadssänkning vid framtida bergbyggen.Det saknas även en kartläggning av befintliga berganläggningar i norden. Det finns mängdermed bergrum, tunnlar och gruvor i norden men i dagsläget finns ingen sammanställning avdessa. En sammanställning som redovisar relevant information om området somberganläggningen ligger i som t.ex. berggrund, jordtyp och potentiell grundvattenbildningskulle även det kunna effektivisera arbetet och minska framtida kostnader då en jämförelsesnabbt kan göras med befintliga anläggningar.En analys av ett enklare prognosverktyg som uppskattar uppfyllnadstiden för olikaberganläggningar endast baserat läckvattenmängd och berganläggningens totala volym visadeatt dessa enklare metoder ofta underskattar uppfyllnadstiden.En metod för teoretisk beräkning av påverkansavståd och kvot mellan grundvattenbildning tilljord och berg undersöktes och påvisades gå att använda i områden med tätt berg, dock medstor osäkerhet.

  • 23.
    Henkel, Herbert
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik.
    Piazolo, Sandra
    Wörman, Anders
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Vattendragsteknik.
    Jing, Lanru
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Teknisk geologi och geofysik.
    A deep rock laboratory in the Dellen impact crater2010Ingår i: GFF, ISSN 1103-5897, E-ISSN 2000-0863, Vol. 132, nr 1, s. 45-54Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The Deep Rock Lab is a platform to establish a comprehensive subsurface bedrock characterization approach, by integrating site characterization techniques applied from different disciplines of geo-mechanics, geochemistry, hydrogeology, structural geology, lithology and geophysics, with consideration of the effects of coupled geological processes of importance for the understanding of groundwater renewal, continental shield deformations, engineering issues related to geological disposal of nuclear waste and CO2, and geothermal energy retrieval in crystalline rocks. The approach will focus on the physics and chemistry of crystalline rocks and groundwater with down-the-hole measurements of relevant variables, using and developing more efficient geo-scientific site investigation techniques for deep boreholes at a chosen site, and develop more advanced down-the-hole measurements and numerical modelling methods with more advanced inversion algorithms to help integrate data interpretations and object representations. The goal is to develop this platform into a long-term research facility that can be readily used by the scientific community for both subsurface fundamental and engineering-oriented research. Such a platform will be especially important for the education of PhD students for generations to come. The integrated drilling and research facility is suggested to be located at the Dellen site. This site has an impact crater with a large range of expected physical property changes with depth, complex and multiple thermal processes that have affected the bedrock, a favorable infrastructure and local supporting activities, and a large body of existing geo-scientific data.

  • 24. Hollesen, J.
    et al.
    Elberling, B.
    Jansson, Per-Erik
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Miljögeokemi och ekoteknik.
    Modelling temperature-dependent heat production over decades in High Arctic coal waste rock piles2011Ingår i: Cold Regions Science and Technology, ISSN 0165-232X, E-ISSN 1872-7441, Vol. 65, nr 2, s. 258-268Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Subsurface heat production from oxidation of pyrite is an important process that may increase subsurface temperatures within coal waste rock piles and increase the release of acid mine drainage, AMD. Waste rock piles in the Arctic are especially vulnerable to changes in subsurface temperatures as the release of AMD normally is limited by permafrost. Here we show that temperatures within a 20 year old heat-producing waste rock pile in Svalbard (78 degrees N) can be modelled by the one-dimensional heat and water flow model (CoupModel) with a new temperature-dependent heat-production module that includes both biological and chemical oxidation processes and heat source depletion over time. Inputs to the model are meteorological measurements, physical properties of the waste rock material and measured subsurface heat-production rates. Measured mean annual subsurface temperatures within the waste rock pile are up to 10 C higher than the mean annual air temperature of -5.8 degrees C. Subsurface temperatures are currently decreasing with 0.5 degrees C per year due to decreasing heat production, which can be modelled using an exponential decay function corresponding to a half-life period of pyrite oxidation of 7 years. Simulations further suggest that subsurface temperatures two years after construction of the pile may have been up to 34.0 degrees C higher than in 2009 and that the release of AMD may have been more than 20 times higher. Sensitivity simulations show that maximum temperatures in the pile would have been up to 30.5-32.5 degrees C lower and that the pile would have been frozen 12-27 years earlier if the pile had been initially saturated with water, constructed with a thickness half of the original or a combination of both. Simulation show that the pile thickness and waste rock pyrite content are important factors controlling the internal build up of heat leading to potential self-incineration. However, site specific measurements of temperature-dependent heat production as well as simulation results show that the heat produced from pyrite oxidation alone cannot cause such a temperature increase and that processes such as heat production from coal oxidation may be equally important. (C) 2010 Elsevier B.V. All rights reserved.

  • 25.
    Jiang, Bin
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, Samhällsbyggnad/GIS-Institutet.
    Yao, Xiaobai
    Geospatial Analysis and Modelling of Urban Structure and Dynamics2010Samlingsverk (redaktörskap) (Övrigt vetenskapligt)
    Abstract [en]

    The increasingly urbanized world has created various problems of environment, climate, consumption of resources, and public health, which are closely linked to the side-effects of urbanization such as sprawl, congestion, housing affordability and loss of open space. Fundamental to the urban problems are two separate yet related issues: urban structure and urban dynamics. The chapters collected in this book present an excellent profile of the current state of geospatial analysis and modelling, and demonstrate how these approaches can contribute to the study of various urban issues. The book addresses key themes including new ways of capturing data digitally at the individual level, the development of systems based around networks, the notion of linking hierarchy to networks to morphology as in complexity theory, and the development of new ways of integrating diverse urban processes through simulation paying careful attention to the basic econometric and statistical principles of spatial analysis.

  • 26.
    Jing, Lanru
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik (flyttat 20130630).
    Feng, X
    Main rock mechanics issues in geological disposal of radioactive wastes: Yanshilixue Yu Gongcheng Xuebao2006Ingår i: Chinese Journal of Rock Mechanics and Engineering, ISSN 1000-6915, Vol. 25, nr 4, s. 833-841Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Geological disposal of radioactive wastes is a multi-disciplinary issue of importance for national interest. It stimulated many challenging scientific and technical issues, and at a higher level, presented a series of demanding requirements for a country's overall research and development programme, its implementation and engineering practice, about basic policies and legislature concerning nuclear energy, defense, waste management and environment. Rock mechanics and rock engineering are very important fields for geological disposal of radioactive wastes, and contribute significantly to the conceptual design, site investigation, engineering design and construction, operation and the long-term safety assessment of the waste repositories. It plays, therefore, a irreplaceable role in the research and development programme of geological disposal of radioactive wastes. In this paper, we first summarizes briefly the main steps about repository system, followed by the major demands for rock mechanics and rock engineering during feasibility study and site investigation, and the major international trends concerning these issues. The focus is placed on the coupled thermo-hydro-mechanical and chemical (THMC) processes and the current status of research in international communities. At the end, the progresses in research and development works in the field of radioactive waste disposal in China are presented; and possible future working directions are discussed.

  • 27. Jing, Lanru
    et al.
    Stephansson, Ove
    Fundamentals of Discrete Element Methods for Rock Engineering2007Bok (Refereegranskat)
  • 28. Jing, Lanru
    et al.
    Stephansson, Ove
    Research results from the DECOVALEX III BECHPAR Projects2005Ingår i: International Journal of Rock Mechanics And Mining Sciences, ISSN 1365-1609, E-ISSN 1873-4545, Vol. 42, nr 5-6, s. 591-870Artikel i tidskrift (Refereegranskat)
  • 29.
    Johansson, Teddy
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Jord- och bergmekanik.
    Artificial Ground Freezingin Clayey Soils: Laboratory and Field Studies of Deformations During Thawing at the Bothnia Line2009Doktorsavhandling, monografi (Övrigt vetenskapligt)
    Abstract [en]

    Artificial ground freezing as a method to temporarily stabilize and create hydraulic sealing in urban as well as in rural areas has been used in a number of Swedish construction projects, particularly during the last decade.

    One problem with the freezing of soil and rock is that fine-grained clayey types of soils have showed a tendency to under certain circumstances, during the thawing process, create a pore water overpressure and to consolidate, despite a change in the external loading conditions. In certain cases, this condition can be a desired effect as the soil mass after a freeze- and thaw cycle acquires overconsolidated properties.

    The main objectives of this study are, to describe and review the knowledge and current state of practice of artificial ground freezing, to increase the understanding about the conceptual behaviour for prognosis of the vertical deformation concerning artificial ground freezing and to compare and discuss results from laboratory and field studies concerning vertical deformation during thawing process for Bothnia soil.

    The field studies and the laboratory tests in this research study have been performed with soil from the freezing of the Bothnia Line in the vicinity of Stranneberget. The Bothnia Line is the railway link between Nyland, north of Kramfors, and Umeå.

    This thesis relates to a part of the Bothnia Line. It deals with the behaviour of soil during thawing by means of temporary stabilization and hydraulic sealing of fine-grained soil through artificial freezing using brine as the cooling agent. However, the reason behind the problem consists of the final deformations due to the thawing process.

    The general conclusions of this study are;

    • the Bothnia soil water content decreased in mean approximately 14 % after a freeze-thaw cycle, which approximately corresponds to; wth = 0.8w – 1.5
    • the decrease of the water content has no correlation to the depth below ground surface, in contrast, there is a strong correlation between the undisturbed soil water content and the magnitude of the decrease in water content
    • the soil liquid limit decreases after a freeze-thaw cycle, simultaneously as the relative share of clay and fine silt grains decreases while the relative share of more coarse grains increases
    • the coarser and denser soil created after a freeze-thaw cycle obtains an increased preconsolidation pressure and an increased undrained shear strength.
  • 30.
    Junjun, Yin
    Högskolan i Gävle, Institutionen för teknik och byggd miljö.
    Exploring the topological patterns of urban street networks from analytical and visual perspectives2009Självständigt arbete på avancerad nivå (masterexamen), 80 poäng / 120 hpStudentuppsats
    Abstract [en]

    Research interests in the studies of complex systems have been booming in many disciplines for the last decade. As the nature of geographic environment is a complex system, researches in this field are anticipated. In particular, the urban street networks in the Geographic Information System (GIS) as complex networks are brought forth for the thesis study. Meanwhile, identifying the scale-free property, which is represented as the power law distribution from a mathematical perspective, is a hot topic in the studies of complex systems. Many previous studies estimated the power law distributions with graphic method, which used linear regression method to identify the exponent value and estimate the quality that the power law fits to the empirical data. However, such strategy is considered to cause inaccurate results and lead to biased judgments. Whereas, the Maximum Likelihood Estimation (MLE) and the Goodness of fit test based on Kolmogorov-Smironv (KS) statistics will provide more solid and trustable results for the estimations. Therefore, this thesis addresses these updated methods exploring the topological patterns of urban street networks from an analytical perspective, which is estimating the power law distributions for the connectivity degree and length of the urban streets. Simultaneously, this thesis explores the street networks from a visual perspective as well. The visual perspective adopts the large network visualization tool (LaNet-vi), which is developed based on the k-core decomposition algorithm, to analyze the cores of the urban street networks. By retrieving the spatial information of the networks from GIS, it actually enables us to see how the urban street networks decomposed topologically and spatially. In particular, the 40 US urban street networks are reformed as natural street networks by using three "natural street" models.

    The results from analytical perspective show that the 80/20 principle still exists for both the street connectivity degree and length qualitatively, which means around 20% natural streets in each network have a connectivity degree or length value above the average level, while the 80% ones are below the average. Moreover, the quantitative analysis revealed the fact that most of the distributions from the street connectivity degree or length of the 40 natural street networks follow a power law distribution with an exponential cut-off. Some of the rest cases are verified to have power law distributions and some extreme cases are still unclear for identifying which distribution form to fit. The comparisons are made to the power law statement from previous study which used the linear regression method. Moreover, the visual perspective not only provides us the chance to see the inner structures about the hierarchies and cores of the natural street networks topologically and spatially, but also serves as a reflection for the analytical perspective. Such relationships are discussed and the possibility of combining these two aspects are pointed out. In addition, the future work is also proposed for making better studies in this field.

  • 31.
    Kaden, Heike
    et al.
    Karlsruhe Institute of Technology.
    Niklasson, Gunnar A.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Königer, F
    Karlsruhe Institute of Technology.
    Schuhmann, R
    Karlsruhe Institute of Technology.
    Emmerich, K
    Karlsruhe Institute of Technology.
    Dielectric spectroscopy of swellable clays at low moisture levels2012Ingår i: BDS 2012. Broadband Dielectric Spectroscopy and its Applications, Leipzig, September 3-7, 2012., 2012, s. 142-Konferensbidrag (Refereegranskat)
  • 32.
    Kamarad, Anthony
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Design and construction of a mobile equipment for thermal response test in borehole heat exchangers2012Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    In 2010, the Ground Source Heat Pumps (GSHPs) market in the European Union went up over one million (1 014 436 units at the end of 2010 according to EUROBSERV’ER 2011). In 2011, it was estimated around 1.25 million according to Bayer et al. (2012). With more than 378 000 units installed in 2010, according to the Swedish heat pump association (SVEP), the Swedish GSHPs market was the first in the EU. As for the French GSHPs market, it was estimated to 151 938 units in service in 2010, which propelled France at the third rank in the EU. However, despite a relatively important number of GSHPs installed in the whole EU, since 2008 GSHP sales have shrank. Even Sweden which has been the most competitive country sees its GSHP sales decline in the first quarter of 2012 (EUROBSERV’ER 2011).

    This report is the achievement of my Master of Science Thesis project. It also represents the end of my studies at INSA Lyon in France and concludes my degree in Energetic and Environment Engineering. This report deals with the improvement of a heat injection apparatus which is available at KTH (Royal Institute of Technology). This equipment is better known as Thermal Response Test (TRT) apparatus. This kind of equipment improves Borehole Heat Exchangers (BHE) design in terms of size and cost benefits. This technology is generally used to design GSHP installations in both domestic and industrial purposes. It allows to determine really important thermal BHE parameters: the thermal conductivity of the ground and the borehole thermal resistance. The report covers a theoretical description of TRT experiments, the reasons and objectives of such a project, the apparatus design and its construction. The last part is dedicated to a first experimental laboratory results and some problems met during the project course. 

  • 33.
    Kizito, Frank
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Miljöbedömning och -förvaltning.
    Ngirane-Katashaya, Gaddi
    Thunvik, Roger
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Miljöbedömning och -förvaltning.
    Using geovisualisation to support participatory problem structuring and decision making for an urban water utility in Uganda2008Ingår i: Applied GIS, ISSN 1832-5505, Vol. 4, nr 2, s. 1-33Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper describes the application of geovisualisation to facilitate participatory identification and structuring of problems in an urban water supply system in Uganda. The city of Kampala has experienced rapid expansion over the years, with a corresponding increase inthe demand for piped water supply. However, this demand was not well matched with expansion of the water supply system, and as a result parts of the city have been facingchronic supply anomalies and insufficiencies. Faced with the task of identifying remedies to theproblems in the system, the city water company undertook a formal participatory problemstructuring and decision analysis process, to try and understand the underlying causes of system failures as well as the geospatial patterns of these failures. As part of this process,analysis, mapping and geovisualisation of data derived from historical records of waterconsumption, as well as records of pipe breakages, supply intermittences, and other recordedcustomer complaints, was done. The maps so produced were key in bringing the variousstakeholders and decision makers to a common understanding of the problem issues, andhelped in the formulation of alternative courses of action. Furthermore, with the establishment of a formal discussion forum for problem analysis and decision making, structured participatory decision making was entrenched within the company’s work ethos. It is hoped that in future,the coupling of the geovisualisation tools with the existing operational databases in thecompany will result in the development of a functional spatial decision support system and adynamic framework for system performance monitoring and reliability assessment.

  • 34.
    Kolesnikov, Anton
    et al.
    Carnegie Inst Washington, Geophys Lab.
    Kutcherov, Vladimir G.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Goncharov, Alexander F.
    Methane-derived hydrocarbons produced under upper-mantle conditions2009Ingår i: Nature geosicence, ISSN 1752-0894, Vol. 2, nr 8, s. 566-570Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    There is widespread evidence that petroleum originates from biological processes(1-3). Whether hydrocarbons can also be produced from abiogenic precursor molecules under the high-pressure, high-temperature conditions characteristic of the upper mantle remains an open question. It has been proposed that hydrocarbons generated in the upper mantle could be transported through deep faults to shallower regions in the Earth's crust, and contribute to petroleum reserves(4,5). Here we use in situ Raman spectroscopy in laser-heated diamond anvil cells to monitor the chemical reactivity of methane and ethane under upper-mantle conditions. We show that when methane is exposed to pressures higher than 2 GPa, and to temperatures in the range of 1,000-1,500 K, it partially reacts to form saturated hydrocarbons containing 2-4 carbons (ethane, propane and butane) and molecular hydrogen and graphite. Conversely, exposure of ethane to similar conditions results in the production of methane, suggesting that the synthesis of saturated hydrocarbons is reversible. Our results support the suggestion that hydrocarbons heavier than methane can be produced by abiogenic processes in the upper mantle.

  • 35.
    Kommana, Karteek
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Implementation of a Geoserver Applicatoin For GIS Data Distribution and Manipulation2013Självständigt arbete på avancerad nivå (masterexamen), 30 poäng / 45 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Accessibility and Interactivity are keywords of information today and that is equally important in science as anywhere else. When scientists share information it benefits if it is intuitive, informative and simple and does not demand expert skills in complicated formats. This master thesis has the aim to investigate open source software tools to design a web map application that can be used by any institute or NGO to distribute their data over internet.

    The Java platform to be implemented is the open source OpenLayers which allow users to view and potentially manipulate GIS map data through a web map application. Whatever GIS data made available on the Geoserver (the host site for the application) can be shared to users worldwide. The user can then: add from a list of available data layers, choose background (e.g. Google Earth, Open Street Map, etc.), zoom in and out, pan, change symbols and colors, add their own data on top and start animation (if applicable).

    The data distributed from the Geoserver can also be viewed and accessed from smartphones whichopens the possibility to make the public part of the larger data gathering task of specific scientific inventories like observations of migrating birds, or whatever indicator a specific scientist is interested in. Data is uploaded to the Geoserver and can then be analyzed and the result is distributed to the public.

  • 36.
    Koyama, Tomofumi
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik.
    Numerical modelling of fluid flow and particle transport in rough rock fracture during shear2005Licentiatavhandling, monografi (Övrigt vetenskapligt)
    Abstract [en]

    The effects of different shearing processes and sample sizes on the fluid flow anisotropy and its impact on particle transport process in rough rock fractures are significant factors that need to be considered in the performance and safety assessments of underground nuclear waste repositories. The subjects, however, have not been adequately investigated previously in either laboratory experiments or numerical modeling. This thesis addresses these problems using numerical modeling approaches.

    The modeling consists of two parts: 1) fluid flow simulations considering more complex but realistic flow boundary conditions during shear processes that cannot be realized readily in laboratory experiments, using digitalized fracture surfaces scanned in the laboratory, so that anisotropic fluid flow induced by shearing with channeling phenomenon can be directly simulated and quantified; 2) particle tracking simulations to demonstrate the impacts of such channeling effects on characteristic properties of particle transport. The numerical method chosen for the simulations is the Finite Element Method (FEM). Scale effects were considered in the simulations by using fracture surface samples of different sizes.

    The distributions of fracture aperture during shear were obtained by numerically generating relative translational and rotary movements between two digitalized surfaces of a rock fracture replica without considering normal loading. From the evolutions of the aperture distributions during the shearing processes, the evolutions of the transmissivity fields were determined by assuming the validity of the cubic law locally. A geostatistical approach was used to quantify the scale effects of the aperture and transmissivity fields. The fluid flow was simulated using different flow boundary conditions, corresponding to translational and rotary shear processes. Corresponding to translational shear (with a 1 mm shear displacement interval up to a maximum shear displacement of 20 mm), three different flow patterns, i.e., unidirectional (flow parallel with and perpendicular to the shear direction), bi-directional and radial, were taken into account. Corresponding to rotary shear (with a 0.5o shear angle interval up to 90o), only the radial flow pattern was considered. The particle transport was simulated using the Particle Tracking Method, with the particles motion following the fluid velocity fields during shear, as calculated by FEM. For the unidirectional particle transport, the breakthrough curves were analyzed by fitting to an analytical solution of 1-D advection-dispersion equation. The dispersivity, Péclet number and tracer velocity, as well as their evolutions during shear, were determined numerically.

    The results show that the fracture aperture increases anisotropically during translational shear, with a more pronounced increase in the direction perpendicular to the shear displacement, causing significant fluid flow channelling. A more significant increase of flow rate and decrease in travel time of the particles in the direction perpendicular to the shear direction is predicted. The particle travel time and characteristics are, correspondingly, much different when such effects caused by shear are included. This finding may have an important impact on the interpretation of the results of coupled hydro-mechanical and tracer experiments for measurements of hydraulic properties of rock fractures, because hydraulic properties are usually calculated from flow test results along the shear directions, with the effects of the significant anisotropic flow perpendicular to the shear direction ignored. The results also show that safety assessment of a nuclear repository, without considering the effects of stress/deformation of rocks on fluid flow and transport processes, may have significant risk potential. The results obtained from numerical simulations show that fluid flow through a single rough fracture changes with increasing sample size, indicating that representativehydro-mechanical properties of the fractures in the field can only be accurately determined using samples of representative sizes beyond their stationarity thresholds.

  • 37.
    Koyama, Tomofumi
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik.
    Stress, Flow and Particle Transport in Rock Fractures2007Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [sv]

    Vätskeflödet och spårämnestransporten i en enskild bergsspricka under skjuvningsprocesser har varit ett viktigt ämne inom bergmekanik. I denna avhandling undersöks ämnet med hjälp av finita element metoden (FEM) och en strömlinjebaserad partikelspårningsmetod. Hänsyn tas till utveckling av öppningar och transmissivitet med skjuvningens förflyttningshistoria under olika normala belastningar baserat på laboratorietester. Fördelningen av spricköppningar och deras utveckling under skjuvning beräknades från de initiala öppningsfälten baserat på det laserscannade provets ytas grovhetskännetecken sam tskjuvningsöppningar uppmätta under de kopplade skjuvning-flöde-spårämneslaboratorietesterna som utförts med nyutvecklad testapparatur i Nagasaki Universitet i Nagasaki, Japan. Tre bergssprickor i granit med olika grovhetskarakteristika användes som utgångsprover från vilka nio gipskopior gjordes. Kopplade skjuvning-flödes tester utfördes sedan under tre normala belastningstillstånd (två nivåer med konstant normal last (KNL) och en konstant normal styvhetstillstånd (KNS). För att visualisera spårämnestransporten tillverkades en transparent övre del av sprickproverna av akryl och en nedre del av gipsbaserat på en kostgjord spänningsspricka i sandsten och de kopplade skjuvning-flödes testerna med vätskevisualisering utfördes med färgspårämne injekterat uppströms och en CCD kamera monterad ovanför för att registrera färgens rörelse. En särskild algoritm användes för att behandla kontaktytorna som nollöppningsämnen användes för att åstadkomma mer exakta flödesfältssimuleringar med FEM. Detta är viktigt för kontinuerliga simuleringar av partikelflöden men uppmärksammas oftast inte tillräckligt i litteraturen. Simuleringsresultaten överensstämde väl med de flödesnivådata som erhölls från laboratorietesterna vilket visade att komplexa historier av spricköppningar och invecklade flöden överensstämde med ändrade normala belastningar och ökande skjuvningsförflyttningar, vilket även fångades av de kopplade skjuvning-flödestesterna av sprickproverna genom visualisering av vätskeflödet. Från de erhållna flödesfälten förutsågs partikeltransporten genom en strömlinjebaserad partikelspårningsmetod med kalkylerade flödeshastighetsfält (vektorer) från flödessimuleringarna genom vilka resultat som flödeshastighetsprofiler, totala flödesnivåer,partikeltransporttid, genombrottskurvor samt Pécletnumret, Pe, erhölls. Vätskeflödet i det vertikala tvådimensionella tvärsnittet av en bergsspricka simulerades även genom att både Navier-Stokes (NS) och Reynoldsekvationerna löstes och partikeltransporten förutsågs genom den strömlinjebaserade partikelspårningsmetoden. Resultaten som erhöllsmed NS och Reynoldsekvationerna jämfördes för att illustrera graden av tillförlitlighet för Reynoldsekvationen för allmänna tillämpningar i praktiken då den senare är betydligt mer beräkningseffektiv för storskaliga problem. Resultaten från flödessimuleringarna visar att den totala flödesnivån och den totala flödeshastigheten förutsedda med NS ekvationer är helt annorlunda motsvarande värden som förutsågs med Reynoldsekvationen. Resultaten visar att en ca 5-10 % för hög uppskattning av flödesnivån erhålls då Reynoldsekvationen används och de ideala parabola hastighetsprofilerna, som definieras av den lokala kubiklagen när Reynoldsekvationen används, inte längre är giltiga särskilt när sprickytornas grovhetskarakteristika ändras med skjuvning. De här avvikelserna i flödesnivå och flödeshastighetsprofiler längs med spricköppningen har en betydande påverkan på partikeltransportuppträdande och de tillhörande egenskaperna såsom rörelsetid och Pécletnummer. Avvikelserna ökar med ökande flödeshastighet och blir mer signifikanta när spricköppningarnas geometri ändras med skjuvning. Forskningsresultaten från dessa studier gav nya insikter i de fysiska uppträdandet av vätskeflöde och masstransporter i bergssprickor vilket är den vetenskapliga basen för många bergmekanikproblem på grundläggande nivå och som har särskild vikt för bergstekniksproblem såsom geotermisk energiutvinning (där flödesnivå i sprickor dominerar produktiviteten för en geotermisk energikälla) och kärnavfallsförvaringsplatser (där transporten av radioaktiva nuklider genom sprickor dominerar den slutgiltigasäkerhetsutvärderingen) i sprickigt berg.

  • 38.
    Koyama, Tomofumi
    et al.
    KTH, Tidigare Institutioner                               , Mark- och vattenteknik.
    Fardin, Nader
    KTH, Tidigare Institutioner                               , Mark- och vattenteknik.
    Jing, Lanru
    KTH, Tidigare Institutioner                               , Mark- och vattenteknik.
    Shear-induced anisotropy and heterogeneity of fluid flow in a single rock fracture with translational and rotary shear displacements: a numerical study2004Ingår i: International Journal of Rock Mechanics And Mining Sciences, ISSN 1365-1609, E-ISSN 1873-4545, Vol. 41, nr 3, s. 426-426Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The effects of rotary shear displacements on fluid flow rates and patterns under shear-flow test conditions were numerically investigated in this paper. A pair of digitized surfaces of a concrete fracture replica of size 250 x 250mm was numerically manipulated to simulate the translational and rotary shearing processes of the sample, which provided the evolution of the aperture distributions during shearing and was used to determine the evolution of the fracture transmissivity field. The translational shear test has bidirectional (x and y) hydraulic head boundary conditions and shearing in the x-direction with 1mm shear displacement interval up to 20mm. The rotary shear test has a 0.5° rotation interval up to 90°. The results of flow simulations show that with increasing rotary shear, the flow rate increases but its pattern becomes rapidly isotropic. For bi-directional translational flow, the flow rate increases with shear but significant channelling, anisotropy and heterogeneity developed with shear displacement. The above flow simulations illustrated the more realistic flow patterns under general fracture deformation modes of translation and rotation, and provided insights for the design of more flexible and complementary laboratory coupled stressflow tests.

  • 39.
    Koyama, Tomofumi
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik.
    Fardin, Nader
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik.
    Jing, Lanru
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik.
    Stephansson, Ove
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik.
    Numerical simulation of shear-induced flow anisotropy and scale-dependent aperture and transmissivity evolution of rock fracture replicas2006Ingår i: International Journal of Rock Mechanics And Mining Sciences, ISSN 1365-1609, E-ISSN 1873-4545, Vol. 43, nr 1, s. 89-106Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Fluid flow anisotropy in a single rock fracture during a shear process is an important issue in rock mechanics and is investigated in this paper using FEM modelling, considering evolutions of aperture and transmissivity with shear displacement history. The distributions of fracture aperture during shearing with large shear displacements were obtained by numerically manipulating relative translational movements between two digitalized surfaces of a rock fracture replica, with changing sample sizes. The scale dependence of the fluid behaviour and properties were also investigated using a fractal approach. The results show that the fracture aperture increases anisotropically during shear with a more pronounced increase in the direction perpendicular to the shear displacement, causing significant fluid flow channelling effect, as also observed by other researchers. This finding may have important impacts on the interpretation of the results of coupled hydro-mechanical experiments for measurements of hydraulic properties of rock fractures because the hydraulic properties are usually calculated from flow test results along the shear directions while ignoring the more significant anisotropic flow perpendicular to the shear direction. This finding indicates that the coupled stress-flow tests of rough rock fractures should be conducted in true three-dimensions if possible. Significant change in fracture aperture/ transmissivity in the out-of-plane direction should be properly evaluated if two-dimensional tests are conducted. Results obtained from numerical simulations also show that fluid flow through a single rough fracture changes with increasing sample size and shear displacements, indicating that representative hydro-mechanical properties of the fractures in the field can only be more reliably determined using samples of large enough sizes beyond the stationarity threshold and tested with larger shear displacements.

  • 40.
    Koyama, Tomofumi
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik.
    Jing, Lanru
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Teknisk geologi och geofysik.
    Effects of shearing processes on the fluid flow and particle transport in a single rock fracture2006Ingår i: Rock mechanics in underground construction: ISRM International Symposium 2006 / [ed] Leung, CF Y, Zhou, YX, 2006, s. 408-Konferensbidrag (Refereegranskat)
  • 41.
    Koyama, Tomofumi
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Teknisk geologi och geofysik.
    Li, B.
    Jiang, Y.
    Jing, Lanru
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Teknisk geologi och geofysik.
    Numerical simulations for the effects of normal loading on particle transport in rock fractures during shear2008Ingår i: International Journal of Rock Mechanics And Mining Sciences, ISSN 1365-1609, E-ISSN 1873-4545, Vol. 45, nr 8, s. 1403-1419Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Fluid flow and tracer transport in a single rock fracture during shear is investigated using the finite element method (FEM) and streamline particle tracking, considering evolutions of aperture and transmissivity with shear displacement histories under different normal stresses, based on laboratory tests. The distributions of fracture aperture and its evolution during shear were calculated from the initial aperture fields, based on the laser-scanned surface roughness of feature replicas of rock fracture specimens, and shear dilations measured during the coupled shear-flow tests in laboratory. The coupled shear-flow tests were performed under two levels of constant normal loading (CNL). A special algorithm for treating the contact areas as zero-aperture elements was used to produce more accurate flow field simulations using FEM. The simulation results agreed well with the flow rate data obtained from the laboratory tests, showing complex histories of fracture aperture and tortuous flow channels with changing normal stresses and increasing shear displacements for the flow parallel with the shear direction. A greater increase was observed for flow in the direction perpendicular to the shear direction, due to the significant flow channels created by the shearing process. From the obtained flow velocity fields, particle transport was predicted using a streamline particle tracking method with the flow velocity fields (vectors) taken from the flow simulations, yielding particle travel times, breakthrough curves, and the Peclet number, Pe. The transport behavior in the fracture is also anisotropic, and advective transport is greater in the direction parallel with the shear direction. The effect of normal stress on the particle transport is significant, and dispersion becomes larger with increasing normal stress.

  • 42.
    Koyama, Tomofumi
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik (flyttat 20130630), Teknisk geologi och geofysik.
    Vilarrasa, Victor
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik (flyttat 20130630), Teknisk geologi och geofysik.
    Jing, Lanru
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik (flyttat 20130630), Teknisk geologi och geofysik.
    Tracer transport in a rough rock fracture during shear: a numerical study2006Ingår i: Proc of the 2nd International Conference on Coupled T-H-M-C Processes in Geo-Systems: Fundamentals, 2006, s. 575-580Konferensbidrag (Refereegranskat)
    Abstract [en]

    The effects of translational shear on particle transport under coupled shear-flow testing conditions in a rough rock fracture were numerically investigated in this study. A pair of digitalized surfaces of a rough concrete fracture replica was numerically manipulated to simulate the translational shearing process without considering normal loading and asperity damage. From the evolutions of the aperture filed during shear, the evolutions of the fracture transmissivity field were determined. Undirectional and bi-directional fluid flow situations were considered, using Finite Element Method (FEM). The results show that translational shear makes rough fractures more permeable, producing a significant change in travel time of the particles. Translational shear yields a significant channelling effect in the direction perpendicular to the shear direction. Bi-directional flow patterns show clearly the shortcommings of the conventional laboratory shear-flow tests with unidirectional flow. These simulations provide a first step towards a better understanding of particle transport in rock fractures.

  • 43.
    Koyama, Tomofumi
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Teknisk geologi och geofysik.
    Vilarrasa, Victor
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Teknisk geologi och geofysik.
    Neretnieks, Ivars
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    Jing, Lanru
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Teknisk geologi och geofysik.
    Shear-induced flow channels and its effect on the particle transport in a single rock fractureIngår i: Hydrogeology Journal, ISSN 1431-2174, E-ISSN 1435-0157Artikel i tidskrift (Övrigt vetenskapligt)
    Abstract [en]

    The effect of mechanical shearing on fluid flow anisotropy and particle transport in rough rock fractures was investigated using numerical modeling. Two opposite surfaces of a rock fracture of 194x194 mm in size were laser scanned to generate their respective digital profiles. Fluid flow through the fracture was simulated using a finite element code that solves the Reynolds equation, while incremental relative movement of the upper surface was maintained numerically to simulate a shearing process without normal loading. The motion of solute particles during shearing was studied using a simple particle-tracking code. It was found that shearing introduces anisotropy in both fluid transmissivity and particle motion, with a greatly increased flow rate and particle travel velocity in the direction perpendicular to the direction of shear. This finding has an important impact in the interpretation of the results of coupled hydro-mechanical and tracer transport experiments of hydraulic and transport properies of rock fractures.

  • 44.
    Liu, Chia-Chuan
    et al.
    Natl Cheng Kung Univ, Tainan, Taiwan.
    Maity, Jyoti Prakash
    Natl Cheng Kung Univ, Tainan, Taiwan.
    Jean, Jiin-Shuh
    Natl Cheng Kung Univ, Tainan, Taiwan.
    Reza, A. H. M. Selim
    Natl Cheng Kung Univ, Tainan, Taiwan.
    Li, Zhaohui
    Univ Wisconsin Parkside, Kenosha, WI USA.
    Nath, Bibhash
    Univ Sydney, Sydney, NSW Australia .
    Lee, Ming-Kuo
    Auburn Univ, Auburn, AL USA.
    Lin, Kao-Hung
    Natl Cheng Kung Univ, Tainan, Taiwan.
    Bhattacharya, Prosun
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik.
    Geochemical characteristics of the mud volcano fluids in southwestern Taiwan and their possible linkage to elevated arsenic concentration in Chianan plain groundwater2012Ingår i: ENVIRONMENTAL EARTH SCIENCES, ISSN 1866-6280, Vol. 66, nr 5, s. 1513-1523Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Fluid and mud samples were collected from Wushanting (WST), Hsiaokunshui (HKS), Yenshuikeng (YSK), Kuantzeling (KZL), and Kunshuiping (KSP) mud volcanoes of southwestern Taiwan. Concentrations of major ions and trace elements in mud volcanic fluids were analyzed to find the possible linkage to elevated arsenic (As) concentrations in the Chianan plain groundwater. The elevated Na+, K+, and Cl- concentrations indicated possible marine origin of the fluids. The trace element concentrations in the mud volcanic fluids were generally low, but the As concentrations were up to 0.12 mg/L. High contents of As, Fe, and Mn were observed in the mud samples. Saturation index calculations indicated that both carbonate and oxide minerals acted as potential sinks for As in the mud volcanic fluids. Arsenic in the dewatering fluids and muds may be transported by the subsurface flow and surface streams as suspended solids and eventually deposited in the Chianan plain aquifers. Under reducing conditions, As may be released from the host minerals (such as Fe- and Mn-oxides/hydroxides), thereby causing widespread groundwater As pollution.

  • 45.
    Malmström, Maria
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Industriell ekologi.
    Docampo Cabaleiro, Eva
    KTH, Skolan för industriell teknik och management (ITM), Industriell ekologi.
    Regenspurg, Simona
    KTH, Skolan för industriell teknik och management (ITM), Industriell ekologi.
    Modelling Ni(II) Sorption in Granitic Groundwater2006Ingår i: Geochimica et Cosmochimica Acta 70 (18):Suppl 1:A387., 2006, s. A387-A387Konferensbidrag (Övrigt vetenskapligt)
  • 46. Marklund, Lars
    et al.
    Simic, Eva
    Wörman, Anders
    Swedish University of Agricultural Sciences.
    The impact of different geological parameters on transport of radionuclides2006Ingår i: Proceedings of the 11th International High Level Radioactive Waste Management Conference, IHLRWM, American Nuclear Society , 2006, s. 369-373Konferensbidrag (Refereegranskat)
    Abstract [en]

    Quaternary deposits and topography are two geological parameters which have a great impact on transport and retardation of radionuclides from a leaking repository of high level nuclear waste in crystalline bedrock. Due to the hydraulic and sorption properties of quaternary deposits, even thin layers significantly increase the residence time of leaking radionuclides. This study also shows that the flow paths predominantly discharge in low areas of the catchments where the layers of quaternary deposits often are relatively deep. The effect of topography is depending on the relationship between the local(kilometres) topography at the repository site and the large scale(hundreds of kilometres) topography surrounding the site area. The areas studied here, are located at discharge areas of deep groundwater flow, driven by large scale topography. Therefore residence times of radionuclides significantly decrease when large scale topography is accounted for. The impact of large scale topography is particularly clear in areas of flatter local topography.

  • 47.
    Marklund, Lars
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik.
    Wörman, Anders
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Vattendragsteknik.
    Characterisation of discharge areas of radionuclides originating from nuclear waste repositories2008Ingår i: Proceedings of the International Conference on Radioecology and Environmental Radioactivity / [ed] Per Strand, Justin Brown and Torun Jolle, 2008Konferensbidrag (Refereegranskat)
  • 48.
    Mas Ivars, Diego
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Teknisk geologi och geofysik.
    Bonded Particle Model for Jointed Rock Mass2010Doktorsavhandling, monografi (Övrigt vetenskapligt)
    Abstract [en]

    Jointed rock masses are formed of intact rock and joints. There-fore, proper characterization of rock mass behavior has to consid-er the combined behavior of the intact rock blocks and that of the joints.

    This thesis presents the theoretical background of the Synthetic Rock Mass (SRM) modeling technique along with example applica-tions. The SRM technique is a new approach for simulating the mechanical behavior of jointed rock masses. The technique uses the Bonded Particle Model (BPM) for rock to represent intact ma-terial and the Smooth-Joint Contact Model (SJM) to represent the in situ joint network. In this manner, the macroscopic behaviour of an SRM sample depends on both the creation of new fractures through intact material, and slip/opening of pre-existing joints. SRM samples containing thousands of non-persistent joints can be submitted to standard laboratory tests (UCS, triaxial loading, and direct tension tests) or tested under a non-trivial stress path repre-sentative of the stresses induced during the engineering activity under study.

    Output from the SRM methodology includes pre-peak properties (modulus, damage threshold, peak strength) and post-peak proper-ties (brittleness, dilation angle, residual strength, fragmentation). Of particular interest is the ability to obtain predictions of rock mass scale effects, anisotropy and brittleness; properties that can-not be obtained using empirical methods of property estimation. Additionally, the nature of yielding and fracturing can be studied as the rock mass fails. This information can improve our understand-ing of rock mass failure mechanisms.

  • 49.
    Min, Ki-Bok
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Teknisk geologi och geofysik.
    Rutqvist, J
    Tsang, C F
    Jing, Lanru
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Teknisk geologi och geofysik.
    Thermally induced mechanical and permeability changes around a nuclear waste repository - a far-field study based on equivalent properties determined by a discrete approach2005Ingår i: International Journal of Rock Mechanics And Mining Sciences, ISSN 1365-1609, E-ISSN 1873-4545, Vol. 42, nr 5-6, s. 765-780Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A numerical investigation is conducted on the impacts of the thermal loading history on the evolution of mechanical response and permeability field of a fractured rock mass containing a hypothetical nuclear waste repository. The geological data are extracted from the site investigation results at Sellafield, England. A combined methodology of discrete and continuum approaches is presented. The results of a series of simulations based on the DFN-DEM (discrete fracture network-distinct element method) approach provide the mechanical and hydraulic properties of fractured rock masses, and their stress-dependencies. These properties are calculated on a representative scale that depends on fracture network characteristics and constitutive models of intact rock and fractures. In the present study, data indicate that the large scale domain can be divided into four regions with different property sets corresponding to the depth. The results derived by the DFN-DEM approach are then passed on to a large-scale analysis of the far-field problem for the equivalent continuum analysis. The large-scale far-field analysis is conducted using a FEM code, ROCMAS for coupled thermo-mechanical process. The results show that the thermal stresses of fractured rock masses vary significantly with mechanical properties determined at the representative scale. Vertical heaving and horizontal tensile displacement are observed above the repository. Observed stress and displacement fields also shows significant dependency on how the mechanical properties are characterized. The permeability changes induced by the thermal loading show that it generally decreases close to the repository. However, change of permeability is small, i.e., a factor of two, and thermally induced dilation of fracture was not observed. Note that the repository excavation effects were not considered in the study. The work presented in this paper is the result of efforts on a benchmark test (BMT2) within the international co-operative projects DECOVALEX III and BENCHPAR.

  • 50.
    Mörén, Lena
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper.
    Bergerosion i utskovskanaler2005Självständigt arbete på avancerad nivå (yrkesexamen), 20 poäng / 30 hpStudentuppsats
    Abstract [sv]

    Dagens klimatsituation ser ut att ge ökad mängd nederbörd i Sverige, vilket innebär att de svenska älvarna kommer att utsättas för allt högre vattenflöden. De flesta av Sveriges älvar är reglerade, d v s längs älvarna finns en mängd större och mindre dammar. Ett högre flöde i älvarna innebär även rikligare tillrinning till dammarna vilket medför att avbördningen från dem måste bli större. Avbördningen från dammarna sker genom utskov och höga vattenflöden i utskovskanalerna kan orsaka erosion på det berg som kanalen vanligen består av. Erosionen är av typen ”blockerosion” där hela bergblock av större eller mindre storlek lösgörs från bergmassan. I värsta fall kan blockerosionen krypa uppströms och erodera dammkroppen bakifrån, vilket skulle kunna innebära att dammen brister.

    Syftet med detta arbete var att identifiera omfattning och typ av bergerosionsproblem som uppkommer i utskovskanaler. Blockerosion uppkommer i regel då forsande vatten skapar tryckskillnader mellan övre och undre ytan på block. Tryckskillnaden kan då skapa tillräckliga lyftkrafter för att block ska lossna. De huvudsakliga faktorerna som styr blockerosionen är bergmassans sprickighet och material, utskovskanalens geometri och vattnets flöde och ytfluktuation. Genom litteraturstudie, numerisk modellanalys samt fältstudie har inverkan på blockerosionen av sprickriktningar utretts. En bergmassa som innehåller sprickgrupper som har liten, nära horisontell, stupning är känslig för vattenbelastning. Stupningsriktningen i förhållande till flödesriktningen har också betydelse för blockerosionen. Stupningsriktning i flödesriktningen gör bergmassan mer känslig för belastning av forsande vatten och gynnar därmed erosionen.

    Utskovskanalerna i Ligga, Harsprånget, Porjus, Satisjaure samt Seitevare har undersökts med avseende på erosionsrisk. Erosionen i Ligga, Harsprånget och Porjus har varit omfattande och detta beror troligtvis på att dessa kanaler har subhorisontella bankningssprickor med litet sprickavstånd. I Satisjaure är bergmassan mycket sprickig, varför denna kanal är mycket känslig för vattnets belastning. Där har dock åtgärder vidtagits så att kanalen ska tåla sitt dimensionerande flöde. I Seitevare är erosionsrisken i kanalens övre del liten.

    Det finns olika metoder för att bedöma erosionsrisken i en bergmassa. Erosionsindexmetoden är en semiempirisk metod som är verifierad med platsobservationer i USA. Med hjälp av observationer från Porjus, Harsprånget och Seitevare har erosionsindexmetodens tillämplighet på svenska kanaler undersökts. För dessa tre observationer verkar metoden fungera bra och har därför även använts i kanalerna i Satisjaure och Ligga.

    Energidämpande åtgärder i kanalerna, såsom energiomvandlargropar och utsprängda trappor i kanalerna, har visats sig vara mycket effektivt för att minska erosionsrisken. En noga dokumentering av utskovskanaler, som t ex kartering och inmätningar, skulle bidra till att erosionsindexmetoden kunde verifieras ytterligare och att en översiktlig bedömning av erosionsrisken i utskovskanaler enkelt kan erhållas.

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