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  • 51.
    Jing, Lanru
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik (flyttat 20130630), Teknisk geologi och geofysik.
    Stephansson, Ove
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik (flyttat 20130630), Teknisk geologi och geofysik.
    Special Issue: Research results from the DECOVALEX III & BENCHPAR projects - Preface2005Inngår i: International Journal of Rock Mechanics And Mining Sciences, ISSN 1365-1609, E-ISSN 1873-4545, Vol. 42, nr 5-6, s. 591-592Artikkel i tidsskrift (Annet vitenskapelig)
  • 52. Karimpour, Marziyeh
    et al.
    Karlson, Mårten
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Teknisk geologi och geofysik.
    Mörtberg, Ulla
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Miljöbedömning och -förvaltning.
    Ecological impacts of transportation infrastructure: A spatial national assessment for Sweden2011Konferansepaper (Fagfellevurdert)
  • 53. Koyama, T.
    et al.
    Jing, Lanru
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Teknisk geologi och geofysik.
    Particle mechanics approach for simulating micro-structure damage and failure processes of rock core samples due to different fluid salinity2006Inngår i: Proc. of the 2nd International Conference on Coupled T-H-M-C Processes in Geo-Systems: Fundamentals, Modeling, Experiments and Applications, GeoProc 2006, 2006, s. 569-574Konferansepaper (Fagfellevurdert)
  • 54. Koyama, T.
    et al.
    Neretnieks, Ivars
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk apparatteknik.
    Jing, Lanru
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Teknisk geologi och geofysik.
    A numerical study on differences in using Navier-Stokes and Reynolds equations for modeling the fluid flow and particle transport in single rock fractures with shear2008Inngår i: International Journal of Rock Mechanics And Mining Sciences, ISSN 1365-1609, E-ISSN 1873-4545, Vol. 45, nr 7, s. 1082-1101Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The study on fluid flow and transport processes of rock fractures in most practical applications involves two fundamental issues: the validity of Reynolds equation for fluid flow (as most often assumed) and the effects of shear displacements on the magnitudes and anisotropy of the fluid flow velocity field. The reason for such concerns is that the impact of the surface roughness of rock fractures is still an unresolved challenging issue. The later has been systematically investigated with results showing that shear displacement plays a dominant role on evolutions of fluid velocity fields, for both magnitudes and anisotropy, but the former has not received examinations in details due to the numerical complexities involving solution of the Navier-Stokes (NS) equations and the representations of fracture geometry during shear. The objective of this paper aims to solve this problem through a FEM modeling effort. Applying the COMSOL Multiphysics code (FEM) and assuming a 2D problem, we consider the coupled hydromechanical effect of fracture geometry change due to shear on fluid flow (velocity patterns) and particle transport (streamline/velocity dispersion), using measured topographical data of natural rock fracture surfaces. The fluid flow in the vertical 2D cross-sections of single rock fractures was simulated by solving both the Navier-Stokes and the Reynolds equation, and the particle transport was predicted by the streamline particle tracking method with calculated flow velocity fields (vectors) from the flow simulations, obtaining results such as flow velocity profiles, total flow rates, particle travel time, breakthrough curves and the Peclet number, Pe, respectively. The results obtained using NS and Reynolds equations were compared to illustrate the degree of the validity of the Reynolds equation for general applications in practice since the later is mush more computationally efficient for solving large-scale problems. The flow simulation results show that both the total flow rate and the flow velocity fields in a rough rock fracture predicted by the NS equation were quite different from those predicted by the Reynolds equation. The results show that a roughly 5-10% overestimation on the flow rate is produced when the Reynolds equation is used, and the ideal parabolic velocity profiles defined by the local cubic law, when Reynolds equation is used, is no longer valid, especially when the roughness feature of the fracture surfaces changes with shear. These deviations of flow rate and flow velocity profiles across the fracture aperture have a significant impact on the particle transport behavior and the associated properties, such as the travel time and Peclet number. The deviations increase with increasing flow velocity and become more significant when fracture aperture geometry changes with shear.

  • 55.
    Koyama, Tomofumi
    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.
    Effects of model scale and particle size on micro-mechanical properties and failure processes of rocks - A particle mechanics approach2007Inngår i: Engineering analysis with boundary elements, ISSN 0955-7997, E-ISSN 1873-197X, Vol. 31, nr 5, s. 458-472Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A numerical procedure to determine the equivalent micro-mechanical properties of intact rocks is presented using a stochastic representative elementary volume (REV) concept and a particle mechanics approach. More than 200 models were generated in square regions with side lengths varying from 1 to 10 cm, using the Monte Carlo simulation technique. Generated particle models were then used for the calculation of equivalent micro-mechanical properties. Results with a core sample of diorite from Aspo, Sweden, show that the variance of the calculated values of mechanical properties decrease significantly as the side lengths of particle models increase, reaching a REV side length about 5 cm with an acceptable variation of 5%, which is equal to the minimum diameter of rock specimen for uniaxial compressive tests suggested by ISRM. The complete stress-strain curve of the diorite rock sample was predicted under uniaxial compression, as the basis for evaluating the damage and failure processes. The unique contribution of this paper is its study on impacts of sample size and particle size distributions on mechanical behaviour of rocks when particle mechanics approaches are used.

  • 56.
    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 fracture2006Inngår i: Rock mechanics in underground construction: ISRM International Symposium 2006 / [ed] Leung, CF Y, Zhou, YX, 2006, s. 408-Konferansepaper (Fagfellevurdert)
  • 57.
    Koyama, Tomofumi
    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.
    Fluid flow and tracer transport simulations for rock fractures under normal loading and shear displacement2007Inngår i: Proceeding of the 11th Int Congr Rock Mech (ISRM 2007), 2007, s. 47-50Konferansepaper (Fagfellevurdert)
  • 58.
    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 modelling of fluid flow tests in a rock fracture with a special algorithm for contact areas2009Inngår i: Computers and geotechnics, ISSN 0266-352X, E-ISSN 1873-7633, Vol. 36, nr 1-2, s. 291-303Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The fluid flow in rock fractures during shear processes has been all important issue in rock mechanics and is investigated in this paper using finite element method (FEM), considering evolutions of aperture and transmissivity with shear displacement histories under different normal stress and normal stiffness conditions as measured during laboratory coupled shear-flow tests. The distributions of fracture aperture and its evolution during shearing were calculated from the initial aperture, based on the laser-scanned sample surface roughness results, and shear dilations measured in the laboratory tests. Three normal loading conditions were adopted in the tests: simple normal stress and mixed normal stress and normal stiffness to reflect more realistic in situ conditions. A special algorithm for treatment of the contact areas as zero-aperture elements was used to produce more accurate flow field simulations, which is important for continued simulations of particle transport but often not properly treated in literature. The simulation results agree well with the measured hydraulic apertures and flow rate data obtained from the laboratory tests, showing that complex histories of fracture aperture and tortuous flow fields with changing normal loading conditions and increasing shear displacements. With the new algorithm for contact areas, the tortuous flow fields and channeling effects under normal stress/stiffness conditions during shearing were more realistically captured, which is not possible if traditional techniques by assuming very small aperture values for the contact areas were used. These findings have an important impact on the interpretation of the results of coupled hydro-mechanical experiments of rock fractures, and on more realistic simulations of particle transport processes in fractured rocks.

  • 59.
    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 shear2008Inngår i: International Journal of Rock Mechanics And Mining Sciences, ISSN 1365-1609, E-ISSN 1873-4545, Vol. 45, nr 8, s. 1403-1419Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 60. Koyama, Tomofumi
    et al.
    Vilarrasa, V.
    Jing, Lanru
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Teknisk geologi och geofysik.
    Particle transport in a rough rock fracture during shear : a numerical study2006Inngår i: Proc. of the 2nd International Conference on Coupled T-H-M-C Processes in Geo-Systems:: Fundamentals, Modeling, Experiments and Applications, GeoProc 2006, 2006, s. 575-580Konferansepaper (Annet vitenskapelig)
  • 61.
    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 study2006Inngår i: Proc of the 2nd International Conference on Coupled T-H-M-C Processes in Geo-Systems: Fundamentals, 2006, s. 575-580Konferansepaper (Fagfellevurdert)
    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.

  • 62.
    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 fractureInngår i: Hydrogeology Journal, ISSN 1431-2174, E-ISSN 1435-0157Artikkel i tidsskrift (Annet vitenskapelig)
    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.

  • 63.
    Lanaro, Flavio
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik (flyttat 20130630), Teknisk geologi och geofysik.
    Tolppanen, Pasi
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik (flyttat 20130630), Teknisk geologi och geofysik.
    Illerström, A.
    Stephansson, Ove
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik (flyttat 20130630), Teknisk geologi och geofysik.
    Characterisation of size, shape and texture of aggregates by fourier analysis of 3-D-laser images2018Inngår i: ISRM International Symposium 2000, IS 2000, International Society for Rock Mechanics , 2018Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A new method for analysis of size, shape and roughness of aggregates based on a 3-D-laser-digitising technique is presented. Measurements of aggregate particles are carried out by a system consisting of a laser sensor and a co-ordinate-measuring machine; the accuracy of the system is ±50 µm. Scanned data are processed to create a digital image of aggregates to be employed in further analyses. Size, shape and volume analysis of particles has been conducted in two ways. A so-called geometrical analysis is based on simple applications of analytical geometry. Another method consists of the Fourier transform analysis of the topography of the two halves of the sample defined by a plane intersecting its mass center. Three-dimensional spectra are obtained as a function of two frequencies along the co-ordinate axes. The cross-sections of the spectrum are then investigated and the pattern of the power spectra gives the dimensions and shape of the particles. When comparing the results from these two methods, a very good agreement is obtained. From the spectrum, the texture component can be identified, which gives the roughness of the particles' surfaces. The new technique by Fourier transform analysis is promising giving repeatable results and performing a combined shape-size-texture analysis of the aggregate particles. .

  • 64. Li, Bo
    et al.
    Jiang, Yujing
    Koyama, Tomofumi
    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.
    Tanabashi, Yoshihiko
    Experimental study of the hydro-mechanical behavior of rock joints using a parallel-plate model containing contact areas and artificial fractures2008Inngår i: International Journal of Rock Mechanics And Mining Sciences, ISSN 1365-1609, E-ISSN 1873-4545, Vol. 45, nr 3, s. 362-375Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In recent years, geological disposal of radioactive wastes is considered to be the most promising option, which requires the understanding of the coupled mechanical, hydraulic and thermal properties of the host rock masses and rock fractures. The hydro-mechanical behavior and properties of rock fractures are usually determined by laboratory experiments on fracture specimens that serve as the basic building block of the constitutive models of fractured rock masses. Laboratory testing of rock fractures involve a number of technical issues that may have significant impacts on the reliability and applicability of the testing results, chief among them are the quantitative estimation of the evolutions of hydraulic transmissivity fields of fractures during shear under different normal constraint conditions, and the sealing techniques when fluid flow during shear is involved. In this study, a new shear-flow testing apparatus with specially designed fluid sealing techniques for rock fractures were developed, under constant normal load (CNL) or constant normal stiffness (CNS) constraint. The topographical data of all fracture specimens were measured before testing to constitute the geometrical models for simulating the change of mechanical aperture distributions during shearing. A number of shear-flow coupling tests were carried out on three kinds of rock fracture specimens to evaluate the influence of morphological properties of rock fractures on their hydro-mechanical behaviour. Some empirical relations were proposed to evaluate the effects of contact area and surface roughness on the behavior of fluid flow through rock fractures.

  • 65. Lindgren, Paula
    et al.
    Ivarsson, Magnus
    Neubeck, Anna
    Broman, Curt
    Henkel, Herbert
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Teknisk geologi och geofysik.
    Holm, Nils G.
    Putative fossil life in a hydrothermal system of the Dellen impact structure, Sweden2010Inngår i: International Journal of Astrobiology, ISSN 1473-5504, E-ISSN 1475-3006, Vol. 9, nr 3, s. 137-146Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Impact-generated hydrothermal systems are commonly proposed as good candidates for hosting primitive life on early Earth and Mars. However, evidence of fossil microbial colonization in impact-generated hydrothermal systems is rarely reported in the literature. Here we present the occurrence of putative fossil microorganisms in a hydrothermal system of the 89 Ma Dellen impact structure, Sweden. We found the putative fossilized microorganisms hosted in a fine-grained matrix of hydrothermal alteration minerals set in interlinked fractures of an impact breccia. The putative fossils appear as semi-straight to twirled filaments, with a thickness of 1-21 mu m, and a length between 10 and 100 mu m. They have an internal structure with segmentation, and branching of filaments occurs frequently. Their composition varies between an outer and an inner layer of a filament, where the inner layer is more iron rich. Our results indicate that hydrothermal systems in impact craters could potentially be capable of supporting microbial life. This could have played an important role for the evolution of life on early Earth and Mars.

  • 66.
    Magnusson, Mimmi K.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Teknisk geologi och geofysik.
    Geoelectrical imaging for interpretation of geological conditions affecting quarry operations2008Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Determination of the subsurface geology is very important for the rock quarry industry. This is primarily done by drilling and mapping of the surface geology. However in Sweden the bedrock is often completely covered by Quaternary sediments making the prediction of subsurface geology quite difficult. Incorrect prediction of the rock-mass quality can lead to economic problems for the quarry. By performing geophysical measurements a more complete understanding of the subsurface geology can be determined. This study shows that by doing 2D-parallel data sampling a 3D inversion of the dataset is possible, which greatly enhances the visualization of the subsurface. Furthermore the electrical resistivity technique together with the induced polarization method proved to be very efficient in detecting fracture frequency, identification of major fracture zones, and variations in rock-mass quality all of which can affect the aggregate quality. With this technique not only the rock-mass quality is determined but also the thickness of the overburden. Implementation of geophysics can be a valuable tool for the quarry industry, resulting in substantial economic benefits.

  • 67.
    Magnusson, Mimmi K.
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Teknisk geologi och geofysik.
    Fernlund, Joanne
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Teknisk geologi och geofysik.
    Dahlin, Torleif
    Department of Engineering Geology, Lund University.
    Geoelectrical imaging in the interpretation of geological conditions affecting quarry operations2010Inngår i: Bulletin of Engineering Geology and the Environment, ISSN 1435-9529, E-ISSN 1435-9537, Vol. 69, nr 3, s. 465-486Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Determination of the subsurface geology is very important for the rock quarry industry. This is primarily done by drilling and mapping of the surface geology. However in Sweden the bedrock is often completely covered by Quaternary sediments making the prediction of subsurface geology quite difficult. Incorrect prediction of the rock-mass quality can lead to economic problems for the quarry. By performing geophysical measurements a more complete understanding of the subsurface geology can be determined. This study shows that by doing 2D-parallel data sampling a 3D inversion of the dataset is possible, which greatly enhances the visualization of the subsurface. Furthermore the electrical resistivity technique together with the induced polarization method proved to be very efficient in detecting fracture frequency, identification of major fracture zones, and variations in rock-mass quality all of which can affect the aggregate quality. With this technique not only the rock-mass quality is determined but also the thickness of the overburden. Implementation of geophysics can be a valuable tool for the quarry industry, resulting in substantial economic benefits.

  • 68. Makurat, A
    et al.
    Zimmerman, R W
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik (flyttat 20130630), Teknisk geologi och geofysik.
    Special issue: Rock physics and geomechanics - Preface2005Inngår i: International Journal of Rock Mechanics And Mining Sciences, ISSN 1365-1609, E-ISSN 1873-4545, Vol. 42, nr 7-8, s. 871-872Artikkel i tidsskrift (Annet vitenskapelig)
  • 69.
    Mas Ivars, Diego
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Teknisk geologi och geofysik.
    Bonded Particle Model for Jointed Rock Mass2010Doktoravhandling, monografi (Annet vitenskapelig)
    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.

  • 70. Millard, A.
    et al.
    Rejeb, A.
    Chijimatsu, M.
    Jing, Lanru
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik (flyttat 20130630), Teknisk geologi och geofysik.
    De Jonge, J.
    Kohlmeier, M.
    Nguyen, T. S.
    Rutqvist, J.
    Souley, M.
    Sugita, Y.
    Evaluation of Thm Coupling on the Safety Assessment of a Nuclear Fuel Waste Repository in a Homogeneous Hard Rock2004Inngår i: Coupled Thermo-Hydro-Mechanical-Chemical Processes in Geo-Systems — Fundamentals, Modelling, Experiments and Applications, Elsevier, 2004, nr C, s. 211-216Kapittel i bok, del av antologi (Fagfellevurdert)
    Abstract [en]

    An evaluation of the importance of the thermo-hydro-mechanical couplings (THM) on the performance assessment of a deep underground storage design has been made as part of the international DECOVALEX III project. It is a numerical study that simulates a generic repository configuration in the near field in a homogeneous hard rock. A periodic pattern comprises a single vertical borehole, containing a canister surrounded by an over-pack and a bentonite layer, and the backfilled upper portion of the gallery. The thermo-hydro-mechanical evolution of the whole configuration is simulated over a period of 100 years. The importance of the rock mass intrinsic permeability has been investigated through three values : 10 -17, 10 -18 and 10 -19 m 2. Comparison of the results predicted by fully coupled THM analysis as well as partially coupled TH, TM and HM analysis, in terms of several predefined indicators, enables us to identify the couplings, which play a crucial role with respect to safety issues. The results demonstrate that temperature is hardly affected by the couplings. In contrast the influence of the couplings on the mechanical stresses is considerable.

  • 71. Millard, A.
    et al.
    Rejeb, A.
    Chijimatsu, M.
    Jing, Lanru
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Teknisk geologi och geofysik.
    De Jonge, J.
    Kohlmeier, M.
    Nguyen, T. S.
    Rutqvist, J.
    Souley, M.
    Sugita, Y.
    Numerical study of the THM effects on the near-field safety of a hypothetical nuclear waste repository - BMT1 of the DECOVALEX III project. Part 2: Effects of THM coupling in continuous and homogeneous rocks2005Inngår i: International Journal of Rock Mechanics And Mining Sciences, ISSN 1365-1609, E-ISSN 1873-4545, Vol. 42, nr 5-6, s. 731-744Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An evaluation of the importance of the thermo-hydro-mechanical couplings (THM) on the performance assessment of a deep underground radioactive waste repository has been made as a part of the international DECOVALEX III project. It is a numerical study that simulates a generic repository configuration in the near field in a continuous and homogeneous hard rock. A periodic repository configuration comprises a single vertical borehole, containing a canister surrounded by an over-pack and a bentonite layer, and the backfilled upper portion of the gallery. The thermo-hydro-mechanical evolution of the whole configuration is simulated over a period of 100 years. The importance of the rock mass's intrinsic permeability has been investigated through scoping calculations with three values: 10(-17), 10(-18) and 10(-19) m(2). Comparison of the results predicted by fully coupled THM analysis as well as partially coupled TH, TM and HM analyses, in terms of several predefined indicators of importance for performance assessment, enables us to identify the effects of the different combinations of couplings, which play a crucial role with respect to safety issues. The results demonstrate that temperature is hardly affected by the couplings. In contrast, the influence of the couplings on the mechanical stresses is considerable.

  • 72. Min, K. B.
    et al.
    Jing, Lanru
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Teknisk geologi och geofysik.
    Rutqvist, J.
    Tsang, C. F.
    Stephansson, Ove
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik.
    Representation of fractured rock masses as equivalent continua using a DFN-DEM approach2005Inngår i: / [ed] G. Barla and M. Barla, 2005, s. 531-538Konferansepaper (Fagfellevurdert)
  • 73.
    Min, Ki-Bok
    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.
    Stephansson, Ove
    Effect of stress on mechanical and hydraulic rock mass properties: Application of DFN-DEM approach on the data from site investigation at Forsmark, Sweden2005Inngår i: EUROCK 2005: IMPACT OF HUMAN ACTIVITY ON THE GEOLOGICAL ENVIRONMENT / [ed] Konecny P, LEIDEN: A A BALKEMA PUBLISHERS , 2005, s. 389-395Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The purpose of this study is to demonstrate the effect of virgin rock stresses on the deformability and permeability of fractured rocks. Geological data were taken from the site investigation at Forsmark, Sweden, conducted by SKB. A set of numerical experiments was conducted to determine the equivalent mechanical properties (essentially, elastic moduli and Poisson's ratio) and permeability using the DFN-DEM (Discrete Fracture Network - Distinct Element Method) approach. The results show that both mechanical properties and permeability are highly dependent on stress. Stress-induced anisotropy of mechanical properties was caused by hyperbolic nature of stiffness of the individual fractures. Stress induced anisotropy of permeability was observed due to different closure behavior of fractures, and in situ stresses influence the fluid pathways in the fractured rock mass. This study shows that proper characterization and consideration of in situ stress is important for the understanding of both mechanical and hydraulic behavior of fractured rocks.

  • 74.
    Min, Ki-Bok
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik (flyttat 20130630), Teknisk geologi och geofysik.
    Rutqvist, J.
    Tsang, C. -F
    Jing, Lanru
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik (flyttat 20130630), Teknisk geologi och geofysik.
    A Block-Scale Stress-Permeability Relationship of a Fractured Rock Determined by Numerical Experiments2004Inngår i: Coupled Thermo-Hydro-Mechanical-Chemical Processes in Geo-Systems — Fundamentals, Modelling, Experiments and Applications, Elsevier, 2004, nr C, s. 269-274Kapittel i bok, del av antologi (Fagfellevurdert)
    Abstract [en]

    We present the stress induced permeability change in a fractured rock with special focuses on 1) fracture closure/opening process, 2) anisotropic stress conditions, and 3) fracture dilation. In order to overcome the limitations from the experimental study on a single fracture or analytical study on orthogonal and/or persistent fracture models, realistic Discrete Fracture Network (DFN) models were used as a geometrical basis. A series of numerical experiments on fluid flow are conducted under different stress boundary conditions for calculation of equivalent permeability. From the analysis on the realistic DFN model, this paper demonstrates the decrease of permeability with the fracture normal closure, increased anisotropy in permeability with anisotropic stress and increase of permeability and significant channelling effect due to fracture dilation. It is shown that block-scale permeability change in fractured rock depends not only on stress magnitude but also on stress orientation and differential stresses.

  • 75.
    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 approach2005Inngår i: International Journal of Rock Mechanics And Mining Sciences, ISSN 1365-1609, E-ISSN 1873-4545, Vol. 42, nr 5-6, s. 765-780Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 76. Nguyen, T. S.
    et al.
    Chijimatsu, M.
    De Jonge, J.
    Jing, Lanru
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik (flyttat 20130630), Teknisk geologi och geofysik.
    Kohlmeier, M.
    Millard, A.
    Rejeb, A.
    Rutqvist, J.
    Souley, M.
    Sugita, Y.
    Implications of Coupled Thermo-Hydro-Mechanical Processes on the Safety of a Hypothetical Nuclear Fuel Waste Repository2004Inngår i: Coupled Thermo-Hydro-Mechanical-Chemical Processes in Geo-Systems — Fundamentals, Modelling, Experiments and Applications, Elsevier, 2004, nr C, s. 225-230Kapittel i bok, del av antologi (Fagfellevurdert)
    Abstract [en]

    In Bench Mark Test no. 1 (BMT1) of the DECOVALEX III international project, we looked at the implications of coupled thermo-hydro-mechanical (THM) processes on the safety of a hypothetical nuclear waste repository. The research teams first calibrated their models with the results of an in-situ heater experiments to obtain confidence in the capability of the models to simulate the main physical processes. Then the models were used to perform scoping calculations for the near-field of the hypothetical repository, with varying degrees of THM coupling complexity. The general conclusion from the BMT1 exercise is that it would be prudent to perform full THM coupling analyses for two main reasons. First, several safety features might be overlooked with lesser degrees of coupling. Second, the ability to predict and interpret several physical processes, during the post-closure monitoring period, is important for confidence building and public acceptance. Such ability is attainable only with fully coupled THM models.

  • 77. Nguyen, Thanh Son
    et al.
    Börgesson, Lennart
    Chijimatsu, Masakazu
    Hernelind, Jan
    Jing, Lanru
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Teknisk geologi och geofysik.
    Kobayashi, Akira
    Rutqvist, Jonny
    A case study on the influence of THM coupling on the near field safety of a spent fuel repository in sparsely fractured granite2009Inngår i: Environmental Geology, ISSN 0943-0105, E-ISSN 1432-0495, Vol. 57, nr 6, s. 1239-1254Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In order to demonstrate the feasibility of geological disposal of spent CANDU fuel in Canada, a safety assessment was performed for a hypothetical repository in the Canadian Shield. The assessment shows that the maximum long term radionuclide release from such repository would meet international criteria for dose rate; however, uncertainties in the assumed evolution of the repository were identified. Such uncertainties could be resolved by the consideration of coupled Thermal-Hydro-Mechanical-Chemical (THMC) processes. In Task A of the DECOVALEX-THMC project, THM models were developed within the framework of the theory of poroelasticity. Such model development was performed in an iterative manner, using experimental data from laboratory and field tests. The models were used to perform near-field simulations of the evolution of the repository in order to address the above-mentioned uncertainties. This paper presents the definition and rationale of task A and the results of the simulations. From a repository safety point of view, the simulations predict that the maximum temperature would be well below the design target of 100A degrees C; however, the stress on the container can marginally exceed the design value of 15 MPa. However, the most important finding from the simulations is that a rock damage zone could form around the emplacement borehole. Such damage zone can extend a few metres from the walls of the emplacement holes, with permeability values that are orders of magnitude higher than the initial values. The damage zone has the potential to increase the radionuclide transport flux from the geosphere; the effect of such an increase should be taken into account in the safety assessment and mitigated if necessary by the provision of sealing systems.

  • 78.
    Nilsson, Tracy
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Teknisk geologi och geofysik.
    The New Madrid Seismic Zone.2011Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The Mississippi River Valley, is hardly known as an earthquake zone, but may in fact be a natural disaster just waiting to happen. Historical records and paleoseismic investigations have shown that large magnitude earthquakes have occurred in the area and there are constantly microquakes all along the New Madrid Fault System. The inhabitants of the Midwest are living in a death trap so long society doesn’t preoperly prepare for earthquakes. The study presented here aims to prove that, as predicting earthquakes is difficult to the point of impossible, the only serious alternative is to reinforce existing buildings and infrastructure and make sure all new developments are seismically safe. The conclusion reached is, that although expensive, building earthquake safe and retrofitting existing buildings, is for the high risk areas by far cheaper than doing nothing when, not if, a new large magnitude earthquake occurs. For a city in the high risk area, the cost of retrofitting the current structures was 13 billion dollar to be compared with the 100 billion dollars in lost lives and properties of a worst case scenario.

  • 79. Reimold, W U
    et al.
    Kelley, S P
    Sherlock, S C
    Henkel, Herbert
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Teknisk geologi och geofysik.
    Koeberl, C
    Laser argon dating of melt breccias from the Siljan impact structure, Sweden: Implications for a possible relationship to Late Devonian extinction events2005Inngår i: Meteoritics and Planetary Science, ISSN 1086-9379, E-ISSN 1945-5100, Vol. 40, nr 4, s. 591-607Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In earlier studies, the 65-75 km diameter Si1jan impact structure in Sweden has been linked to the Late Devonian mass extinction event. The Siljan impact event has previously been dated by K-Ar and Ar-Ar chronology at 342-368 Ma, with the commonly quoted age being 362.7 +/- 2.2 Ma (2 sigma, recalculated using currently accepted decay constants). Until recently, the accepted age for the Frasnian/Famennian boundary and associated extinction event was 364 Ma, which is within error limits of this earlier Si1jan age. Here we report new Ar-Ar ages extracted by laser spot and laser step heating techniques for several melt breccia samples from Si1jan (interpreted to be impact melt breccia). The analytical results show some scatter, which is greater in samples with more extensive alteration; these samples generally yield younger ages. The two samples with the least alteration yield the most reproducible weighted mean ages: one yielded a laser spot age of 377.2 +/- 2.5 Ma (95% confidence limits) and the other yielded both a laser spot age of 376.1 +/- 2.8 Ma (95% confidence limits) and a laser stepped heating plateau age over 70.6% (39)Ar release of 377.5 +/- 2.4 Ma (2 sigma). Our conservative estimate for the age of Siljan is 377 2 Ma (95% confidence limits), which is significantly different from both the previously accepted age for the Frasnian/Famennian (F/F) boundary and the previously quoted age of Siljan. However, the age of the F/F boundary has recently been revised to 374.5 +/- 2.6 Ma by the International Commission for Stratigraphy, which is, within error, the same as our new age. However, the currently available age data are not proof that there was a connection between the Si1jan impact event and the F/F boundary extinction. This new result highlights the dual problems of dating meteorite impacts where fine-grained melt rocks are often all that can be isotopically dated, and constraining the absolute age of biostratigraphic boundaries, which can only be constrained by age extrapolation. Further work is required to develop and improve the terrestrial impact age record and test whether or not the terrestrial impact flux increased significantly at certain times, perhaps resulting in major extinction events in Earth's biostratigraphic record.

  • 80.
    Renman, Agnieszka
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik.
    Hylander, Lars D.
    Renman, Gunno
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Teknisk geologi och geofysik.
    Transformation and removal of nitrogen in reactive bed filter materials designed for on-site wastewater treatment2008Inngår i: Ecological Engineering: The Journal of Ecotechnology, ISSN 0925-8574, E-ISSN 1872-6992, Vol. 34, nr 3, s. 207-214Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Nitrogen (N) and phosphorus (P) should be removed and recycled from wastewater in order to reduce the nutrient load to recipient waters, avoid contamination of groundwater and conserve resources. Nitrogen removal and transformation were studied in domestic wastewater percolating in unsaturated conditions through 0.5 m long columns containing potential filter materials. Six materials (three types of slag, limestone, opoka, Polonite(R) and sand) were compared at a design loading rate of 85 L m(-2) d(-1) during 67 weeks. All materials transformed ammonium efficiently to nitrate (>98%). Apparent removal of inorganic N was shown only by the coarsest slag and by Polonite(R), possibly due to losses through volatilisation. All other filter materials leached nitrate at the column effluent. Total N content was highest in the surface layer of the column material, with decreasing values with depth. In contrast, carbon

  • 81.
    Renman, Agnieszka
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik.
    Renman, Gunno
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Teknisk geologi och geofysik.
    Gustafsson, Jon Petter
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik.
    Hylander, Lars D.
    Metal removal by bed filter materials used in domestic wastewater treatment2009Inngår i: Journal of Hazardous Materials, ISSN 0304-3894, E-ISSN 1873-3336, Vol. 166, nr 2-3, s. 734-739Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Bed filters using reactive materials are an emerging technology for on-site wastewater treatment. Used materials, which are enriched with phosphorus, can be used as a fertiliser or soil amendment. However the materials can also be enriched with metals from the wastewater. Six materials (opoka, sand, Polonite (R), limestone, two types of blast furnace slag) exposed to long-term wastewater loading in columns and in a compact filter well filled with Polonite were investigated for metal removal and accumulation. Wastewater applied to the columns had low heavy metal concentrations in the order Zn > Cu > Mn > Ni > Cr. All columns were able to remove 53%-83% of Zn except those filled with sand. Polonite demonstrated a high removal capacity of Mn (>98%), while only the slag materials were able to remove Ni. All materials showed increased Cu, Cr(III). Mn. Pb and Zn content after filtration. Speciation calculations showed that high concentrations of dissolved organic matter might have prevented efficient metal removal, particularly in the case of Cu. The low content of toxic heavy metals in the studied filter materials studied would probably not restrict their use as a fertiliser or soil amendment.

  • 82.
    Robison Fernlund, Joanne
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Teknisk geologi och geofysik.
    3-D image analysis size and shape method applied to the evaluation of the Los Angeles test2005Inngår i: Engineering Geology, ISSN 0013-7952, E-ISSN 1872-6917, Vol. 77, nr 02-jan, s. 57-67Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The 3-D image analysis (IA) method for size and shape determination has been used to evaluate the Los Angeles test (LA test) on granitic gneiss aggregates from the Vandle Rock Quarry north of Stockholm, Sweden. The method determines, very accurately, the 3-D size and shape of each particle in the sample. The size and shape of each particle is determined both prior and subsequent to the Los Angeles test. Thus, the size reduction and shape change of the particles is determined. Application of the image analysis method to the Los Angeles test makes it possible to evaluate the results in more detail than is possible with traditional sieve analysis. A correlation to the Los Angeles value is suggested. The method is quick, easy and extremely accurate. It can replace Sieve analysis, Flakiness index test, and Shape index test for coarse aggregate material. The 3-D image analysis method is a dynamic tool that can be used to evaluate other aggregate tests that rely on sieving for evaluation.

  • 83.
    Robison Fernlund, Joanne
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Teknisk geologi och geofysik.
    Image analysis method for determining 3-D shape of coarse aggregate2005Inngår i: Cement and Concrete Research, ISSN 0008-8846, E-ISSN 1873-3948, Vol. 35, nr 8, s. 1629-1637Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A 3-D method for particle shape determination of coarse aggregates using image analysis, IA, is presented. It is based on the measures the axial length of all three axis of every particle in a coarse aggregate sample. Two images of the entire aggregate sample are taken, in lying and standing positions. Since the particle's intermediate axes are measured in both images they can be used to couple the shortest and longest axial dimensions for each particle. The method allows an interpretation of length/thickness, length/width and width/thickness ratios of all the particles and is thus comparable to the flakiness and shape index tests.

  • 84.
    Robison Fernlund, Joanne
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Teknisk geologi och geofysik.
    Image analysis method for determining 3-D size distribution of coarse aggregates2005Inngår i: Bulletin of Engineering Geology and the Environment, ISSN 1435-9529, E-ISSN 1435-9537, Vol. 64, nr 2, s. 159-166Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A new 3-D grain size distribution analysis method for coarse aggregates using image analysis is presented. The method is designed for a laboratory environment and requires no sieving, only imaging of the aggregate. A luminous background material eliminates unwanted shadow effects. Particles are placed so they are not touching, thus the images of the aggregates are of good quality allowing an easy and accurate image analysis with no preprocessing. All three axial lengths of every particle are measured. The results can be plotted either as a continuous curve or showing the axial size of each and every particle. The latter allows the frequency of particles in the tails to be easily evaluated. Good agreement exists between the size distribution curves obtained from the Image Analysis and hand measurements using the Danish Box.

  • 85.
    Robison Fernlund, Joanne
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Teknisk geologi och geofysik.
    Zimmerman, Robert W.
    Kragic, Danica
    KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Centrum för Autonoma System, CAS.
    Influence of volume/mass on grain-size curves and conversion of image-analysis size to sieve size2007Inngår i: Engineering Geology, ISSN 0013-7952, E-ISSN 1872-6917, Vol. 90, nr 04-mar, s. 124-137Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Image analysis of aggregates does not measure the same size as sieve analysis. The size of aggregates, determined by sieve analysis, is presented with respect to the percent cumulative mass, whereas image analysis does not measure mass. Results are often presented in percent particles or percent area. Several researchers have claimed that more accurate volume and mass determinations are necessary for accurate construction of grain-size curves. In the present work, several methods for reconstructing volume and thus mass of aggregates from image analysis (IA) have been tested to see how they influence the grain-size distribution curves. The actual mass of the individual particles was found to have little or no influence on the grain-size distribution curve, which is normalized and thus insensitive to mass. Accurate conversion of image-analysis size to sieve size is dependent upon how particles pass through sieves. Most existing methods base their conversion of image-analysis size to sieve size on the intermediate axis, multiplied by some factor. The present work shows that there is no direct correlation between the intermediate axes and sieve size. A universal conversion of image-analysis size to sieve size has been developed, using the minimum-bounding square around the minimum projected area. This measure yields very good correlation with sieve-analysis results.

  • 86. Rutqvist, J.
    et al.
    Chijimatsu, M.
    Jing, Lanru
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Teknisk geologi och geofysik.
    Millard, A.
    Nguyen, T. S.
    Rejeb, A.
    Sugita, Y.
    Tsang, C. F.
    A numerical study of THM effects on the near-field safety of a hypothetical nuclear waste repository - BMT1 of the DECOVALEX III project. Part 3: Effects of THM coupling in sparsely fractured rocks2005Inngår i: International Journal of Rock Mechanics And Mining Sciences, ISSN 1365-1609, E-ISSN 1873-4545, Vol. 42, nr 5-6, s. 745-755Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    As a part of the international DECOVALEX III project, and the European BENCHPAR project, the impact of thermal-hydrological-mechanical (THM) couplings on the performance of a bentonite-back-filled nuclear waste repository in near-field crystalline rocks is evaluated in a Bench-Mark Test problem (BMT1) and the results are presented in a series of three companion papers in this issue. This is the third paper with focuses on the effects of THM processes at a repository located in a sparsely fractured rock. Several independent coupled THM analyses presented in this paper show that THM couplings have the most significant impact on the mechanical stress evolution, which is important for repository design, construction and post-closure monitoring considerations. The results show that the stress evolution in the bentonite-back-filled excavations and the surrounding rock depends on the post-closure evolution of both fields of temperature and fluid pressure. It is further shown that the time required to full resaturation may play an important role for the mechanical integrity of the repository drifts. In this sense, the presence of hydraulically conducting fractures in the near-field rock might actually improve the mechanical performance of the repository. Hydraulically conducting fractures in the near-field rocks enhances the water supply to the buffers/back-fills, which promotes a more timely process of resaturation and development of swelling pressures in the back-fill, thus provides timely confining stress and support to the rock walls. In one particular case simulated in this study, it was shown that failure in the drift walls could be prevented if the compressive stresses in back-fill were fully developed within 50 yr, which is when thermally induced rock strain begins to create high differential (failure-prone) stresses in the near-field rocks. Published by Elsevier Ltd.

  • 87. Rutqvist, Jonny
    et al.
    Borgesson, Lennart
    Chijimatsu, Masakazu
    Hernelind, Jan
    Jing, Lanru
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Teknisk geologi och geofysik.
    Kobayashi, Akira
    Nguyen, Son
    Modeling of damage, permeability changes and pressure responses during excavation of the TSX tunnel in granitic rock at URL, Canada2009Inngår i: Environmental Geology, ISSN 0943-0105, E-ISSN 1432-0495, Vol. 57, nr 6, s. 1263-1274Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper presents numerical modeling of excavation-induced damage, permeability changes, and fluid-pressure responses during excavation of a test tunnel associated with the tunnel sealing experiment (TSX) at the Underground Research Laboratory (URL) in Canada. Four different numerical models were applied using a wide range of approaches to model damage and permeability changes in the excavation disturbed zone (EDZ) around the tunnel. Using in situ calibration of model parameters, the modeling could reproduce observed spatial distribution of damage and permeability changes around the tunnel as a combination of disturbance induced by stress redistribution around the tunnel and by the drill-and-blast operation. The modeling showed that stress-induced permeability increase above the tunnel is a result of micro and macrofracturing under high deviatoric (shear) stress, whereas permeability increase alongside the tunnel is a result of opening of existing microfractures under decreased mean stress. The remaining observed fracturing and permeability changes around the periphery of the tunnel were attributed to damage from the drill-and-blast operation. Moreover, a reasonably good agreement was achieved between simulated and observed excavation-induced pressure responses around the TSX tunnel for 1 year following its excavation. The simulations showed that these pressure responses are caused by poroelastic effects as a result of increasing or decreasing mean stress, with corresponding contraction or expansion of the pore volume. The simulation results for pressure evolution were consistent with previous studies, indicating that the observed pressure responses could be captured in a Biot model using a relatively low Biot-Willis' coefficient, alpha a parts per thousand 0.2, a porosity of n a parts per thousand 0.007, and a relatively low permeability of k a parts per thousand 2 x 10(-22) m(2), which is consistent with the very tight, unfractured granite at the site.

  • 88. Rutqvist, Jonny
    et al.
    Bäckström, Ann
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Teknisk geologi och geofysik.
    Chijimatsu, Masakazu
    Feng, Xia-Ting
    Pan, Peng-Zhi
    Hudson, John
    Jing, Lanru
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Teknisk geologi och geofysik.
    Kobayashi, Akira
    Koyama, Tomofumi
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Teknisk geologi och geofysik.
    Lee, Hee-Suk
    Huang, Xiao-Hua
    Rinne, Mikael
    Shen, Baotang
    A multiple-code simulation study of the long-term EDZ evolution of geological nuclear waste repositories2009Inngår i: Environmental Geology, ISSN 0943-0105, E-ISSN 1432-0495, Vol. 57, nr 6, s. 1313-1324Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This simulation study shows how widely different model approaches can be adapted to model the evolution of the excavation disturbed zone (EDZ) around a heated nuclear waste emplacement drift in fractured rock. The study includes modeling of coupled thermal-hydrological-mechanical (THM) processes, with simplified consideration of chemical coupling in terms of time-dependent strength degradation or subcritical crack growth. The different model approaches applied in this study include boundary element, finite element, finite difference, particle mechanics, and elasto-plastic cellular automata methods. The simulation results indicate that thermally induced differential stresses near the top of the emplacement drift may cause progressive failure and permeability changes during the first 100 years (i.e., after emplacement and drift closure). Moreover, the results indicate that time-dependent mechanical changes may play only a small role during the first 100 years of increasing temperature and thermal stress, whereas such time-dependency is insignificant after peak temperature, because of decreasing thermal stress.

  • 89.
    Rutqvist, Jonny
    et al.
    KTH, Tidigare Institutioner, Mark- och vattenteknik.
    Chijimatsu, M.
    Jing, Lanru
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik (flyttat 20130630), Teknisk geologi och geofysik.
    Millard, A.
    Nguyen, T. S.
    Rejeb, A.
    Sugita, Y.
    Tsang, C. F.
    Evaluation of the Impact of Thermal-Hydrological-Mechanical Couplings in Bentonite and Near-Field Rock Barriers of a Nuclear Waste Repository in Sparsely Fractured Hard Rock2004Inngår i: Coupled Thermo-Hydro-Mechanical-Chemical Processes in Geo-Systems — Fundamentals, Modelling, Experiments and Applications, Elsevier, 2004, nr C, s. 217-223Kapittel i bok, del av antologi (Fagfellevurdert)
    Abstract [en]

    As part of the international DECOVALEX III project and the European BENCHPAR project, this paper evaluates the impact of thermal-hydrological-mechanical (THM) couplings on the performance of a bentonite back-filled nuclear waste repository in sparsely fractured hard rock. The significance of THM coupling on the performance of a hypothetical repository is evaluated by several independent coupled numerical analyses. Moreover, the influence of a discrete fracture intersecting a deposition hole is discussed. The analysis shows that THM couplings have the most impact on the mechanical behaviour of bentonite-rock system, which is important for repository design considerations.

  • 90.
    Tafesse, Solomon
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Teknisk geologi och geofysik.
    Physical characterization of coarse clasts with 3D image-analysis method: development, evaluation and application2012Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    This thesis presents a novel three dimensional (3D) image-analysis method for characterizing the physical characteristics of coarse particles in the field, and introduces new methodology for the total analysis of glacial till samples.

    The novel image analysis method, called the GID method, is capable of determining the size, shape and surface texture of each individual clast analysed. Images of particles are taken in the field and analysis is done in the laboratory. Therefore the GID method makes it feasible to analyse statistically representative large sample in short period; for poorly sorted sediments, such as till, one-tonne is required if the analysis includes cobble size. The capability of the GID method was demonstrated by studying coarse clasts (20-200 mm) from till. There is excellent agreement in the results of the size distribution obtained from the GID method and sieve analysis. The GID method results for size and shape parameters show high and very high repeatability. The particle angularity in the GID method has not been measured to acceptable level; the repeatability test shows some variability.

    The new methodology for total analysis of till applied the GID method at four different locations in Sweden. The total analysis included 3D size and shape distribution of coarse particles coupled to electrical resistivity, lithological distribution and magnetic susceptibility of the clasts. The results show clear difference in the till samples from the different sites.

  • 91.
    Tafesse, Solomon
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Teknisk geologi och geofysik.
    Physical properties of coarse particles in till coupled to bedrock composition based on new 3D image analysis method2010Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The physical properties of the coarse fraction of the till (0.4 to 20 cm) and the surface boulders have been studied at two different sites in Sweden. The research work included: development of a new image analysis software for 3D size and shape measurements of particles; lithological analysis on multiple size fractions in till and magnetic susceptibility survey on coarse till clasts, surface boulders and local bedrock.

    The new 3D image analysis method provides an enormous amount of size and shape data for each particle in the coarse fraction (2 to 20 cm) in till. The method is suitable for field study, cost effective and the software is executable in Matlab. The field imaging method together with the image analysis software give non subjective results of size and shape of coarse particles and makes it feasible and easy to study representative sample size, which is one tonne for testing clasts of size up to 20 cm.

    The lithological analysis of the multiple size fraction of the till clasts has been investigated on six different size fractions of the till (0.4 to 20 cm); the result of the different samples from the two sites shows that this method can potentially be used as a stratigraphic tool in the areas where there is no unique indicator lithologies.

    The magnetic susceptibility has been made on the surface boulders, the 6-20 cm till fraction and on insitu bedrock outcrops near to the study sites. The method has good potential for determining stratigraphic relationships between different till units as well as for determining the provenance ofcoarse clasts and surface boulders.

  • 92.
    Tafesse, Solomon
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Teknisk geologi och geofysik.
    Fernlund, Joanne
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Teknisk geologi och geofysik.
    Bergholm, Fredrik
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik.
    Digital sieving-Matlab based 3-D image analysis2012Inngår i: Engineering Geology, ISSN 0013-7952, E-ISSN 1872-6917, Vol. 137-138, s. 74-84Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A new image analysis technique for determining the three-dimensional size and shape distribution of coarse particles has been developed. It entails acquiring a pair of images, one each of the maximum and minimum projected area of the particles. Glow-In-the-Dark beads were used to create luminous background, thus it is named the GID method. In this study the size and shape distribution of four coarse-grained samples, size varies from 2 to 20. cm, have been analyzed. The size distribution of the samples obtained from the GID analysis is comparable to sieve analysis results, and has an extra advantage of being applicable in the field. The algorithm was developed in Matlab; therefore users could make some optimization in the program to meet their own needs as the program code is open source.

  • 93.
    Tafesse, Solomon
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Teknisk geologi och geofysik.
    Fernlund, Joanne M. Robison
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Teknisk geologi och geofysik.
    Repeatability of GID Image-analysis method for assessment size, shape and angularity of coarse particlesInngår i: Engineering Geology, ISSN 0013-7952, E-ISSN 1872-6917Artikkel i tidsskrift (Annet vitenskapelig)
  • 94.
    Tafesse, Solomon
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Teknisk geologi och geofysik.
    Fernlund, Joanne M. Robison
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Teknisk geologi och geofysik.
    Sun, Wenjuan
    Bergholm, Fredrik
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik.
    Evaluation of image analysis methods for the quantification of particle angularityInngår i: Sedimentology, ISSN 0037-0746, E-ISSN 1365-3091Artikkel i tidsskrift (Annet vitenskapelig)
  • 95.
    Tafesse, Solomon
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Teknisk geologi och geofysik.
    Robison Fernlund, Joanne M.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Teknisk geologi och geofysik.
    Sun, Wenjuan
    Bergholm, Fredrik
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik.
    Evaluation of image analysis methods used for quantification of particle angularity2013Inngår i: Sedimentology, ISSN 0037-0746, E-ISSN 1365-3091, Vol. 60, nr 4, s. 1100-1110Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Angularity is an important parameter in the characterization of particle morphology that is used to interpret the transport history of particles in sedimentary deposits. In the past, visual classification using silhouette charts was widely used to determine particle angularity, but this approach is subjective and time-consuming. With advances in modern image analysis techniques and low-cost software packages, it is possible to rapidly quantify particle angularity more objectively than using visual classification methods. This study re-examines the performance of three existing image analysis methods and one new image analysis procedure, applied to six rock and sediment samples that were visually different in angularity. To facilitate comparison between the angularity results, measurements were reduced to rankings for each aggregate sample. These results show that the four image analysis methods rank the angularity of the samples differently, and that none rank the mean angularity index in the same order as the angularity ranking using visual classification. Therefore, further research is needed to develop an image analysis method that can quantify the angularity of sedimentary particles more precisely.

  • 96.
    Tafesse, Solomon
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Teknisk geologi och geofysik.
    Sun, Wenjuan
    Virginia Tech, Department of Civil and Environmental Engineering.
    Fernlund, Joanne
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Teknisk geologi och geofysik.
    Linbing, Wang
    Virginia Tech, Department of Civil and Environmental Engineering.
    A New Image Analysis Technique to Quantify Particle AngularityArtikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Angularity is a fundamental morphological descriptor of a particle; it determines the aggregate performance in asphalt and concrete works. This paper introduces an innovative matlab based image analysis technique to quantify the angularity of an aggregate. The algorithm is based on application of two successive b-spline smoothing techniques around the aggregate profile. The first b-spline smoothing curve is generated by joining the mid-points of the adjacent segments; and the second smoothing curve is generated by a smoothing function upon the first b-spline. Then the distribution of the perpendicular distance between these two-b-splines is evaluated, which provides an excellent estimate to the aggregate angularity. In this paper the angularity index of six aggregate samples is determined using our new technique. Then we compared the index obtained with an existing Aggregate Imaging Measurement System (AIMS) and the measurement from the two methods revealed good similarity. Therefore our new method can be considered as a useful alternative in the aggregate industry for distinguishing the angularity of the samples obtained from different sources.

  • 97.
    Tong, Fuguo
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Teknisk geologi och geofysik.
    Numerical modeling of coupled thermo-hydro-mechanical processes in geological porous media2010Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Coupled Thermo-Hydro-Mechanical (THM) behavior in geological porous media has been a subject of great interest in many geoengineering disciplines. Many attempts have been made to develop numerical prediction capabilities associated with topics such as the movement of pollutant plumes, gas injection, energy storage, geothermal energy extraction, and safety assessment of repositories for radioactive waste and spent nuclear fuel. This thesis presents a new numerical modeling approach and a new computer code for simulating coupled THM behavior in geological porous media in general, and compacted bentonite clays in particular, as buffer materials in underground radioactive waste repositories.

    New governing equations were derived according to the theory of mixtures, considering interactions among solid-phase deformation, flows of water and gases, heat transport, and phase change of water. For three-dimensional problems, eight governing equations were formulated to describe the coupled THM processes.

    A new thermal conductivity model was developed to predict the thermal conductivity of geological porous media as composite mixtures. The proposed model considers the combined effects of solid mineral composition, temperature, liquid saturation degree, porosity and pressure on the effective thermal conductivity of the porous media. The predicted results agree well with the experimental data for MX80 bentonite.

    A new water retention curve model was developed to predict the suction-saturation behavior of the geological porous media, as a function of suction, effective saturated degree, temperature, porosity, pore-gas pressure, and the rate of saturation degree change with time. The model was verified against experimental data of the FEBEX bentonite, with good agreement between measured and calculated results.

    A new finite element code (ROLG) was developed for modeling fully coupled thermo-hydro-mechanical processes in geological porous media. The new code was validated against several analytical solutions and experiments, and was applied to simulate the large scale in-situ Canister Retrieval Test (CRT) at Äspö Hard Rock Laboratory, SKB, Sweden, with good agreement between measured and predicted results. The results are useful for performance and safety assessments of radioactive waste repositories.

  • 98.
    Tong, Fuguo
    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.
    Bin, Tian
    A Water Retention Curve Model for the Simulation of Coupled Thermo-Hydro-Mechanical Processes in Geological Porous Media2012Inngår i: Transport in Porous Media, ISSN 0169-3913, E-ISSN 1573-1634, Vol. 91, nr 2, s. 509-530Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper presents a new water retention curve (WRC) model for the simulation of coupled thermo-hydro-mechanical processes in geological porous media. The model simultaneously considers the impact of porosity and temperature on suction, for both wetting processes and drying processes. The model is based on an idealization of porous geological media as having an isotropic and homogeneous microscopic pore structure. Suction is expressed as a function of degree of saturation, porosity, surface tension of the water-air interface, and the length of air bubble perimeter of the pores per unit area on a random 2D cross-section of the medium. The tension of water-air interface is written as a function of temperature, and the length of perimeter of the water-air interface of the pores becomes a function of porosity and degree of saturation. The final equation of the new WRC is a function of suction, effective degree of saturation, temperature, porosity, pore-gas pressure, and the rate of degree of saturation change with time for both wetting and drying processes. The model was used to fit experimental data of the FEBEX bentonite, with good agreements between measured and calculated results.

  • 99.
    Tong, Fuguo
    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.
    Zimmerman, Robert W.
    A 3D FEM simulation of the buffer and buffer-rock interfacebehaviour of the Canister Retrieval Test (CRT) at Äspö HRL: 29 Sep-01Oct 2009, Luxembourg. European Commission2009Inngår i: Proceedings Conference of impact of THMC processes on thesafety of underground radioactive waste repositories, 2009Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper presents a 3D FEM model for simulating the coupled THM behaviour of the buffer and buffer-rock interface behaviour of the Canister Retrieval Test conducted at the Äspö Hard Rock Laboratory, Sweden. The effect of the interface between the canister and buffer was also included. New numerical techniques were developed for more efficient FEM formulation and equation solution, and for modeling saturated or partially saturated water flow, gas flow and heat transfer in buffer and interfaces. The numerical results compare well with the measured data, and the reasonably good agreement between simulated and measured results indicates that the coupled THM processes of buffer material can be accurately predicted by the newly developed THM model and computer code.

  • 100.
    Tong, Fuguo
    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.
    Zimmerman, Robert W.
    A fully coupled thermo-hydro-mechanical model for simulating multiphase flow, deformation and heat transfer in buffer material and rock masses2010Inngår i: International Journal of Rock Mechanics And Mining Sciences, ISSN 1365-1609, E-ISSN 1873-4545, Vol. 47, nr 2, s. 205-217Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper presents a numerical method for modeling coupled thermo-hydro-mechanical processes of geomaterials with multiphase fluid flow. A FEM code has been developed and validated for modeling the behavior of porous geological media, and is equally applicable for modeling coupled THM processes in rocks. The governing equations are based on the theory of mixtures applied to the multiphysics of porous media, considering solid phase deformation, multiphase fluid flow, and heat transport. New numerical techniques have been developed for more efficient FEM formulation and equation solution for modeling saturated or partially saturated water flow, gas flow and heat transfer indeformable porous media, as are commonly encountered in performance and safety assessment of underground radioactive repositories. The code has been validated against an experimental benchmark test, which involves bentonite under laboratory conditions, with good results. Several critical outstanding issues for modeling coupled processes of geomaterials are discussed indepth.

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