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  • 1. Andersson, J. C.
    et al.
    Feng, X.
    Pan, P.
    Koyama, T.
    Kwon, S.
    Lee, C. S.
    Rinne, M.
    Shen, B.
    Lan, H.
    Martin, C. D.
    Chen, Y.
    Zhou, C.
    Blaheta, R.
    Kohut, R.
    Jing, Lanru
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering (moved 20130630).
    Modeling the Äspö Pillar stability experiment2010In: Rock Mechanics in Civil and Environmental Engineering - Proceedings of the European Rock Mechanics Symposium, EUROCK 2010, 2010, p. 787-790Conference paper (Refereed)
    Abstract [en]

    This paper presents results of the 1st stages ofTaskAof the Decovalex 2011 project, the numerical modeling of the Äspö Pillar Stability experiment performed by the Äspö Hard Rock Laboratory of the Swedish Nuclear Fuel and Waste Management Company (SKB). The objective is to perform back calculation of the Äspö pillar behavior using state of the art numerical modeling techniques for the material behavior. The work is divided into three stages and it is the first stage of thework that will be presented in this paper. Seven international teams from six different countries participated in the task and contributed to the results presented in this paper, concerning back calculation of uniaxial and triaxial compressive core testing and elastic back calculation of the stress path for excavation-induced stresses. The results are useful for understanding the occurrence of spalling in the upper part of the pillar during excavation and the stress path modeling gives the first approximation of the yielding strength of the pillar. The calculated results agree well with observations measured during experiment.

  • 2.
    Baghbanan, Alireza
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Engineering Geology and Geophysics.
    Jing, Lanru
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Engineering Geology and Geophysics.
    Effects of size and stress on deformability and strength of fractured rocks with correlated fracture aperture and length2008In: International Journal of Rock Mechanics And Mining Sciences, ISSN 1365-1609, E-ISSN 1873-4545Article in journal (Other academic)
  • 3.
    Baghbanan, Alireza
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Engineering Geology and Geophysics.
    Jing, Lanru
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Engineering Geology and Geophysics.
    Hydraulic properties of fractured rock masses with correlated fracture length and aperture2007In: International Journal of Rock Mechanics And Mining Sciences, ISSN 1365-1609, E-ISSN 1873-4545, Vol. 44, no 5, p. 704-719Article in journal (Refereed)
    Abstract [en]

    Permeability of fractured rocks is investigated considering the correlation between distributed fracture aperture and trace length, based on a newly developed correlation equation. The influence of the second moment of the lognormal distribution of apertures on the existence of representative elementary volume (REV), and the possibility of equivalent permeability tensor of the fractured rock mass, is examined by simulating flow through a large number of stochastic discrete fracture network (DFN) models of varying sizes and varying fracture properties.

    The REV size of the DFN models increases with the increase of the second moment of the lognormal distribution, for both the correlated and uncorrelated cases. The variation of overall permeability between different stochastic realizations is an order of magnitude larger when the aperture and length are correlated than when they are uncorrelated. The mean square error of the directional permeability increases with increasing value of the second moment of the lognormal distribution function, and good fitting to an ellipsis of permeability tensor can only be reached with very large sizes of DFN models, compared with the case of constant fracture aperture, regardless of fracture trace length.

  • 4.
    Baghbanan, Alireza
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Engineering Geology and Geophysics.
    Jing, Lanru
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Engineering Geology and Geophysics.
    Scale and stress effects on permeability tensor of fractured rocks with correlated fracture length and aperture2008In: Thermo-Hydromechanical and chemical coupling in geomaterials and applications: Proceedings of the 3rd International Symposium GeoProc’2008 / [ed] Nicolas Burlion, Jian-Fu Shao, 2008, p. 439-446Conference paper (Refereed)
    Abstract [en]

    The effect of stress on permeability tensor and Representative Elementary Voliume (REV) of fractured rock masses is studied using a Discrete Element Approach (DEM). A new nonlinear model of rock fractures is developed for prediction of normal stress-normal displacement behavior of fractures based on the correlation between fracture aperture and length distributions. The results show that at small differential stress ratios K (=horizontal/vertical stresses) the overall permeability of fracture networks is generally decreased. However contribution from a few large fractures of higher hydraulic conductivity prevents drastic reduction of the overall permeability, compare with DFN models of constant fracture apertures regardless of fracture trace length. With large values of differential stress ratios, the overall permeability of the DFN models is controlled by a combination of highly conductive larger fractures and fractures with shear slipping and dilation. With increasing differential stress ratios (K=1,3,4 and 5) the REV of a fractured rock may exist at much larger model sizes comparing with the model without stress (K=0).

  • 5.
    Baghbanan, Alireza
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Engineering Geology and Geophysics.
    Jing, Lanru
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Engineering Geology and Geophysics.
    Stress effects on permeability in fractured rock mass with correlated fracture length and aperture2008In: International Journal of Rock Mechanics And Mining Sciences, ISSN 1365-1609, E-ISSN 1873-4545, Vol. 45, no 8, p. 1320-1334Article in journal (Refereed)
    Abstract [en]

    The effect of stress on permeability and fluid flow patterns in fractured rock masses is studied when distributed fracture aperture is correlated with fracture trace length, using a discrete element method (DEM). The basic assumptions are that the rock matrix is impermeable and linearly elastic, and that the fluid flows only in fractures. A new nonlinear algorithm is developed for prediction of normal stress-normal displacement behavior of fractures based on the Bandis model and the correlation between aperture and length. The results show that when small stress ratios (K = horizontal/vertical stress) are applied at the model boundaries, the overall permeability of the fracture network is generally decreased. However, contribution from a few large fractures of higher hydraulic conductivity prevents drastic reduction of the overall permeability, compared with models that assume uniform fracture apertures. With large values of the stress ratio, both the overall permeability and flow patterns are controlled by a combination of highly conductive larger fractures and fractures with shear slipping and dilation, with much increased overall permeability and shear-induced flow channeling. With increasing stress ratios, it becomes more and more difficult to establish an equivalent permeability tensor and representative elementary volume (REV) of a fractured rock, compared with the unstressed model. These results show significant difference between correlated and non-correlated aperture and fracture length distributions, and highlight more significant scale and stress dependence of hydro-mechanical behavior of fractures rocks when geometric parameters of rock fractures are correlated.

  • 6. Borgesson, L.
    et al.
    Chijimatsu, M.
    Fujita, T.
    Nguyen, T. S.
    Rutqvist, J.
    Jing, Lanru
    KTH, Superseded Departments, Land and Water Resources Engineering.
    Thermo-hydro-mechanical characterisation of a bentonite-based buffer material by laboratory tests and numerical back analyses2001In: International Journal of Rock Mechanics And Mining Sciences, ISSN 1365-1609, E-ISSN 1873-4545, Vol. 38, no 1, p. 95-104Article in journal (Refereed)
    Abstract [en]

    This paper presents some laboratory tests performed on the bentonite used as buffer material in the engineered barrier experiment in Kamaishi mine in Japan and a collective effort of four research groups to characterise the coupled thermo-hydro-mechanical behaviour of the bentonite by comparing numerical calculations with the laboratory test results. Each research group used finite element programs with constitutive models capable to simulate both liquid and vapour flux of water, heat transfer, volume change, swelling pressure and mechanical deformation. Numerical calibrations were performed against results obtained from three types of laboratory tests: water infiltration tests, thermal gradient tests and swelling pressure tests. Parameter values, which could not be directly measured in laboratory tests, were obtained with these calculations.

  • 7. Bäckström, A.
    et al.
    Antikainen, Janne
    Backers, Tobias
    Feng, X.
    Jing, Lanru
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Engineering Geology and Geophysics.
    Kobayashi, A.
    Koyama, Tomofumi
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Engineering Geology and Geophysics.
    Pan, P.
    Rinne, M.
    Shen, B.
    Hudson, J.A.
    Numerical modelling of unaxial compressive failure of granite with and without saline porewater2008In: International Journal of Rock Mechanics And Mining Sciences, ISSN 1365-1609, E-ISSN 1873-4545, Vol. 45, no 7, p. 1126-1142Article in journal (Refereed)
  • 8.
    Bäckström, Ann
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Engineering Geology and Geophysics.
    Jing, Lanru
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Engineering Geology and Geophysics.
    Koyama, Tomofumi
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Engineering Geology and Geophysics.
    et al.,
    Numerical modelling of uniaxial compressive failure of granite with and without saline porewater2008In: International Journal of Rock Mechanics And Mining Sciences, ISSN 1365-1609, E-ISSN 1873-4545, Vol. 45, no 7, p. 1126-1142Article in journal (Refereed)
    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.

  • 9. Chen, Y.
    et al.
    Hu, R.
    Zhou, C.
    Jing, Lanru
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Land and Water Resources Engineering.
    A permeability evolution model for crystalline rocks subjected to coupled thermo-hydro-mechanical loading2013In: Chinese Journal of Rock Mechanics and Engineering, ISSN 1000-6915, Vol. 32, no 11, p. 2185-2195Article in journal (Refereed)
    Abstract [en]

    An anisotropic damage model was established for fluid-saturated crystalline rocks of low permeability in coupled thermo-hydro-mechanical (THM) loading conditions by using the micromechanical approach in the framework of thermodynamics. The proposed damage model accounts for the impacts of some important micromechanisms, such as the interstitial water pressure, normal stiffness recovery induced by compressed microcracks and sliding and shear dilatancy of closed microcracks, on the macromechanical properties of rocks under non-isothermal condition. On this basis, using various homogenization approaches, estimates were presented for the variations in effective permeability of cracked rocks induced by anisotropic damage propagation. The predictive limitations associated with the lower bound estimates for the effective permeability of damaged rocks were discussed; and a rigorous upper bound estimate was then presented to account for the influence of some important microstructural features, such as the connectivity and persistence of microcrack system, on the permeability variation. Existing laboratory tests on granite samples for damage-induced variation in permeability in triaxial condition and for uniaxial mechanical response after high-temperature thermal treatment, together with the in-situ measurements of excavation-induced damage zone and permeability variation in the surrounding rock of the TSX tunnel, were used to validate the proposed models.

  • 10. Chen, Y.
    et al.
    Zhou, C.
    Tong, Fuguo
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering (moved 20130630).
    Jing, Lanru
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering (moved 20130630).
    Numerical model for fully coupled THM processes with multiphase flow and code validation2009In: Chinese Journal of Rock Mechanics and Engineering, ISSN 1000-6915, Vol. 28, no 4, p. 649-665Article in journal (Refereed)
    Abstract [en]

    A numerical model for fully coupled THM processes with multiphase flow in porous media was developed based on the momentum, mass and energy conservation laws of the continuum mechanics and the averaging approach of the mixture theory over a solid-liquid-gas three-phase system. To characterize multiphase THM coupling and to make the governing equations closed, complete and compatible, six processes and their coupling effects were considered, including stress-strain, water flow, gas flow, vapor flow, heat transport and porosity evolution processes. The physical phenomena such as phase transition, gas solubility in liquid, thermo-osmosis, moisture transfer and moisture swelling were modeled. As a result, the relative humidity of pore gas was defined on a sounder physical basis, avoiding the traditional definition as a negative exponential function of suction and absolute temperature. By selecting displacements, pore water pressure, pore gas pressure, pore vapor pressure, temperature and porosity as basic unknown variables, a finite element formulation was then established, and a three-dimensional computer code, THYME3D, was developed, with each node of 8 degrees of freedom. The bentonite THM Mock-up experiments performed by CEA were employed to validate the mathematical model and the software. The main coupling mechanisms involved in the experiments were satisfactorily simulated in the validation, and the effects of the governing equations, the constitutive relations and the parameters on the coupled THM processes were understood. The work developed enabled further in-depth research on fully coupled THM or THMC processes in porous media.

  • 11. Chen, Y.F
    et al.
    Zhou, C.B
    Mao, X.Y
    Jing, Lanru
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering (moved 20130630), Engineering Geology and Geophysics.
    Numerical simulation of coupled thermal elastic behaviors for hard rock pillar in Äspö Pillar Stability Experiment, Sweden2010In: Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering, ISSN 1000-4548, Vol. 32, no 8, p. 1200-1206Article in journal (Refereed)
    Abstract [en]

    The goal of the Äspö Pillar Stability Experiment performed in Äspö Hard Rock Laboratory, Sweden is to investigate the mechanical response and progressive failure process of ahard rock pillar during excavation and heating. Numerical simulation of the thermalelastic behaviors for the pillar is one of the three tasks of the DECOVALEX-2011 project. The evolutions of stress, deformation and temperature of the pillar are modeled by using a coupled thermal elasticity model. The research results demonstrate that the thermalelasticity model is suitable for describing the coupled thermal mechanical behaviors of the pillar during excavation and heating. The stress redistribution and temperature evolution processes of the pillar are largely modeled, and the failure process and its propagation are qualitatively analyzed. The major limitations of the thermal elasticity model are its absence of the multiphase flow and progressive failure processes. The model developed and the modeling experiences accumulated in this study may be helpful for the stability and safety assessment of the hard granite host rock in China's Beishan preselected area for high-level radioactive waste disposal.

  • 12. Chen, Yifeng
    et al.
    Hu, Shaohua
    Wei, Kai
    Hu, Ran
    Zhou, Chuangbing
    Jing, Lanru
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Land and Water Resources Engineering.
    Experimental characterization and micromechanical modeling of damage-induced permeability variation in Beishan granite2014In: International Journal of Rock Mechanics And Mining Sciences, ISSN 1365-1609, E-ISSN 1873-4545, Vol. 71, p. 64-76Article in journal (Refereed)
    Abstract [en]

    Triaxial compression tests with measurements of permeability were performed on core granite samples taken at 450-550 m depth from the Beishan area in Gansu Province, a potential site for China's high-level radioactive waste (HLW) disposal. Corresponding to the distinct features in the stress-strain behaviors, the permeability of the Beishan granite was found to evolve with a clear permeability decrease in the initial microcrack closure region, a constant permeability value in the elastic region and a dramatic permeability increase in the crack growth region. The permeability increases by up to and over two orders of magnitude as deviatoric stress increases up to sample failure; but at a given deviatoric stress, the permeability reduces remarkably with the increase of confining pressure. An empirical upper bound permeability model was presented by relating the mechanisms involved in the microstructure alteration to the permeability change, and the experimental results were well simulated by the proposed model. Combined with field geological characterization and numerical simulation, the implications of the experimental results for China's HLW disposal were discussed.

  • 13. Chen, Yifeng
    et al.
    Hu, Shaohua
    Zhou, Chuangbing
    Jing, Lanru
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering.
    Micromechanical Modeling of Anisotropic Damage-Induced Permeability Variation in Crystalline Rocks2014In: Rock Mechanics and Rock Engineering, ISSN 0723-2632, E-ISSN 1434-453X, Vol. 47, no 5, p. 1775-1791Article in journal (Refereed)
    Abstract [en]

    This paper presents a study on the initiation and progress of anisotropic damage and its impact on the permeability variation of crystalline rocks of low porosity. This work was based on an existing micromechanical model considering the frictional sliding and dilatancy behaviors of microcracks and the recovery of degraded stiffness when the microcracks are closed. By virtue of an analytical ellipsoidal inclusion solution, lower bound estimates were formulated through a rigorous homogenization procedure for the damage-induced effective permeability of the microcracks-matrix system, and their predictive limitations were discussed with superconducting penny-shaped microcracks, in which the greatest lower bounds were obtained for each homogenization scheme. On this basis, an empirical upper bound estimation model was suggested to account for the influences of anisotropic damage growth, connectivity, frictional sliding, dilatancy, and normal stiffness recovery of closed microcracks, as well as tensile stress-induced microcrack opening on the permeability variation, with a small number of material parameters. The developed model was calibrated and validated by a series of existing laboratory triaxial compression tests with permeability measurements on crystalline rocks, and applied for characterizing the excavation-induced damage zone and permeability variation in the surrounding granitic rock of the TSX tunnel at the Atomic Energy of Canada Limited's (AECL) Underground Research Laboratory (URL) in Canada, with an acceptable agreement between the predicted and measured data.

  • 14. Chen, Yifeng
    et al.
    Zhou, Chuangbing
    Jing, Lanru
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Engineering Geology and Geophysics.
    Modeling coupled THM processes of geological porous media with multiphase flow: Theory and validation against laboratory and field scale experiments2009In: Computers and geotechnics, ISSN 0266-352X, E-ISSN 1873-7633, Vol. 36, no 8, p. 1308-1329Article in journal (Refereed)
    Abstract [en]

    A FEM model for analysis of fully coupled multiphase flow, thermal transport and stress/deformation in geological porous media was developed based on the momentum, mass and energy conservation laws of the continuum mechanics and the averaging approach of the mixture theory over a three phase (solid-liquid-gas) system. Six processes (i.e. stress-strain, water flow, gas flow, vapor flow, heat transport and porosity evolution processes) and their coupling effects are considered, which not only makes the problem well-defined, but renders the governing PDEs closed, complete. compact and compatible. Displacements, pore water pressure, pore gas pressure, pore vapor pressure, temperature and porosity are selected as basic unknowns. The physical phenomena such as phase transition, gas solubility in liquid, thermo-osmosis, moisture transfer and moisture swelling are modeled. As a result, the relative humidity and other related variables in porous media can be evaluated on a sounder physical basis. A three dimensional computer code, THYME3D, was developed, with eight degrees of freedom at each node. The laboratory CEA Mock-up test and the field scale FEBEX benchmark test on bentonite performance assessment for underground nuclear waste repositories were used to validate the numerical model and the software. The coupled THM behaviors of the bentonite barriers were satisfactorily simulated, and the effects and impacts of the governing equations, constitutive relations and property parameters on the coupled THM processes were understood in terms of more straightforward interpretation of physical processes at microscopic scale of the porous media. The work developed enables further in-depth research on fully coupled THM or THMC processes in porous media.

  • 15. Chijimatsu, M.
    et al.
    Jing, Lanru
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering (moved 20130630), Engineering Geology and Geophysics.
    Millard, A.
    Nguyen, T. S.
    Rejeb, A.
    Rutqvist, Jonny
    KTH, Superseded Departments, Land and Water Resources Engineering.
    Souley, M.
    Sugita, Y.
    Building Confidence in the Mathematical Models by Calibration With A T-H-M Field Experiment2004In: Coupled Thermo-Hydro-Mechanical-Chemical Processes in Geo-Systems — Fundamentals, Modelling, Experiments and Applications, Elsevier, 2004, no C, p. 193-198Chapter in book (Refereed)
    Abstract [en]

    Geological disposal of nuclear fuel wastes relies on the concept of multiple barrier systems. In order to predict the performance of these barriers, mathematical models have been developed, verified and validated against analytical solutions, laboratory tests and field experiments within the international DECOVALEX project. These models in general consider the full coupling of thermal (T), hydrological (H) and mechanical (M) processes that would prevail in the geological media around the repository. This paper shows the process of building confidence in the mathematical models by calibration with a reference T-H-M experiment with realistic rock mass conditions and bentonite properties and measured outputs of thermal, hydraulic and mechanical variables.

  • 16. Chijimatsu, M.
    et al.
    Nguyen, T. S.
    Jing, Lanru
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Engineering Geology and Geophysics.
    De Jonge, J.
    Kohlmeier, M.
    Millard, A.
    Rejeb, A.
    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 1: Conceptualization and characterization of the problems and summary of results2005In: International Journal of Rock Mechanics And Mining Sciences, ISSN 1365-1609, E-ISSN 1873-4545, Vol. 42, no 5-6, p. 720-730Article in journal (Refereed)
    Abstract [en]

    Geological disposal of the spent nuclear fuel often uses the concept of multiple barrier systems. In order to predict the performance of these barriers, mathematical models have been developed, verified and validated against analytical solutions, laboratory tests and field experiments within the international DECOVALEX III project. These models in general consider the full coupling of thermal (T), hydraulic (H) and mechanical (M) processes that would prevail in the geological media around the repository. For Bench Mark Test no. 1 (BMTI) of the DECOVALEX III project, seven multinational research teams studied the implications of coupled THM processes on the safety of a hypothetical nuclear waste repository at the near-field and are presented in three accompanying papers in this issue. This paper is the first of the three companion papers, which provides the conceptualization and characterization of the BMT1 as well as some general conclusions based on the findings of the numerical studies. It also shows the process of building confidence in the mathematical models by calibration with a reference T-H-M experiment with realistic rock mass conditions and bentonite properties and measured outputs of thermal, hydraulic and mechanical variables.

  • 17. Chijimatsu, Masakazu
    et al.
    Borgesson, Lenart
    Fujita, Tomoo
    Jussila, Petri
    Nguyen, Son
    Rutqvist, Jonny
    Jing, Lanru
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Engineering Geology and Geophysics.
    Model development and calibration for the coupled thermal, hydraulic and mechanical phenomena of the bentonite2009In: Environmental Geology, ISSN 0943-0105, E-ISSN 1432-0495, Vol. 57, no 6, p. 1255-1261Article in journal (Refereed)
    Abstract [en]

    In the international DECOVALEX-THMC project, five research teams study the influence of thermal-hydro-mechanical (THM) coupling on the safety of a hypothetical geological repository for spent fuel. In order to improve the analyses, the teams calibrated their bentonite models with results from laboratory experiments, including swelling pressure tests, water uptake tests, thermally gradient tests, and the CEA mock-up THM experiment. This paper describes the mathematical models used by the teams, and compares the results of their calibrations with the experimental data.

  • 18. Feng, Q.
    et al.
    Fardin, N.
    Jing, Lanru
    KTH, Superseded Departments, Land and Water Resources Engineering.
    Stephansson, O.
    A new method for in-situ non-contact roughness measurement of large rock fracture surfaces2003In: Rock Mechanics and Rock Engineering, ISSN 0723-2632, E-ISSN 1434-453X, Vol. 36, no 1, p. 3-25Article in journal (Refereed)
    Abstract [en]

    This paper presents a new method for in-situ non-contact measurements of fracture roughness by using a total station (TS). The TS is a non-reflector geodetic instrument usually used for measuring control points in surveying and mapping. By using a special-developed program, the TS can be used as a point-sensor laser scanner to scan a defined area of the fracture surface automatically, in field or in laboratory, at a distance away from the target surface. A large fracture surface can be automatically scanned with a constant interval of the sampling points, both within a defined area or along a cross-section of the exposed rock face. To quantify fracture roughness at different scales and obtain different densities of the scanned points, the point interval can be selected with the minimum interval of I rum. A local Cartesian co-ordinate system needs to be established first by the TS in front of the target rock face to define the true North or link the measurements to a known spatial co-ordinate system for both quantitative and spatial analysis of fracture roughness. To validate the method, fracture roughness data recorded with a non-reflector TS was compared with the data captured by a high-accuracy 3D-laser scanner. Results of this study revealed that both primary roughness and waviness of fracture surfaces can be quantified by the TS in the same accuracy level as that of the high accuracy laser scanner. Roughness of a natural fracture surface can be sampled without physical contact in a maximum distance of tens of meters from the rock faces.

  • 19. Feng, Q.
    et al.
    Sjogren, P.
    Stephansson, O.
    Jing, Lanru
    KTH, Superseded Departments, Land and Water Resources Engineering.
    Measuring fracture orientation at exposed rock faces by using a non-reflector total station2001In: Engineering Geology, ISSN 0013-7952, E-ISSN 1872-6917, Vol. 59, no 1-2, p. 133-146Article in journal (Refereed)
    Abstract [en]

    Measurements of fracture orientation are usually taken by using a compass-inclinometer device on exposed rock faces. The drawbacks when using this method is that it is time-consuming if many fractures are measured and that measurement might be impossible if the rock face cannot be safely reached physically. To improve field mapping of rock fractures, a method for applying a non-reflector total station to measuring fracture orientation is presented in this paper. A non-reflector total station is a geodetic device that captures three-dimensional co-ordinates of target points without using a reflector. Therefore, physical touching the rock surfaces is no longer required. To determine a fracture orientation, co-ordinates of a set of points on the exposed fracture surface are captured at a distance from the rock face. The best-fit plane of the exposed fracture surface is defined by the co-ordinates of the target points, and the orientation (e.g. dip angle and dip direction) of the fracture surface is determined as that of its best-fit plane. This paper presents the technical procedure and a portable system designed for the field mapping of fracture orientation. Results of a case study performed at an exposed rock face are also included.

  • 20. Feng, X. -T
    et al.
    Liu, J.
    Jing, Lanru
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering (moved 20130630), Engineering Geology and Geophysics.
    Research and application on coupled t-h-m-c processes of geological media in china - a review2004In: Coupled Thermo-Hydro-Mechanical-Chemical Processes in Geo-Systems — Fundamentals, Modelling, Experiments and Applications, Elsevier, 2004, no C, p. 37-48Chapter in book (Refereed)
    Abstract [en]

    Theoretical models of coupled T-H-M-C processes of geological media and the associated numerical solutions have become an attractive research focus in geomechanics and related fields in China. This paper provides a systematic overview of the past progress in the fundamental studies of the coupled THM models and numerical methods, and their applications in the fields of oil/gas reservoir, coal mining, and water resources engineering works. The key areas of weakness in research in this field are also outlined and possible directions for the future development are discussed.

  • 21.
    Henkel, Herbert
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    Piazolo, Sandra
    Wörman, Anders
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Hydraulic Engineering.
    Jing, Lanru
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Engineering Geology and Geophysics.
    A deep rock laboratory in the Dellen impact crater2010In: GFF, ISSN 1103-5897, E-ISSN 2000-0863, Vol. 132, no 1, p. 45-54Article in journal (Refereed)
    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.

  • 22. Hudson, J. A.
    et al.
    Jing, Lanru
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering.
    Demonstration of coupled models and their validation against experiment: The current phase DECOVALEX 20152013In: Rock Characterisation, Modelling and Engineering Design Methods - Proceedings of the 3rd ISRM SINOROCK 2013 Symposium, Taylor & Francis Group, 2013, p. 391-396Conference paper (Refereed)
    Abstract [en]

    The DECOVALEX Project (DEmonstration of COupled models and their VALidation against EXperiment) has been operating since 1992 with the objective of developing thermo-hydro-mechanical coupled computer modelling in order to provide the necessary support for the design of underground radioactive waste repositories. The Project consists of Benchmark Tests which are synthetic models for comparison of different research teams' computer modelling results (verification), and Test Cases which are simulations of actual physical cases to establish whether the modelling does in fact represent the rock reality (validation). An international consortium of Funding Organisations supports the DECOVALEX work, currently the following ten Funding Organisations: BGR/UFZ (Germany), CAS (China), DOE (USA), ENSI (Switzerland), IRSN (France), JAEA (Japan), KAERI (Korea), NDA (UK), NRC (USA) and RAWRA (Czech Republic). In this paper, we explain the 2011-2015 DECOVALEX modelling tasks which cover the range of argillaceous, sedimentary and crystalline rocks.

  • 23. Hudson, J. A.
    et al.
    Stephansson, O.
    Andersson, J.
    Tsang, C. F.
    Jing, Lanru
    KTH, Superseded Departments, Land and Water Resources Engineering.
    Coupled T-H-M issues relating to radioactive waste repository design and performance2001In: International Journal of Rock Mechanics And Mining Sciences, ISSN 1365-1609, E-ISSN 1873-4545, Vol. 38, no 1, p. 143-161Article in journal (Refereed)
    Abstract [en]

    In this paper. coupled thermo-hydro-mechanical (THM) issues relating to nuclear waste repository design and performance are reviewed. Concise statements. that were developed from DECOVALEX discussions, on the current state-of-knowledge are presented. Section 1 describes the THM background and the interface with performance assessment (PA). The role of THM issues in the overall repository design context is amplified in Section 2, which includes a review of the processes in terms of repository excavation. operation and post-closure stages. It is important to understand the overall context, the detailed THM issues, the associated modelling and how these issues will be resolved in the wider framework. Also, because uncoupled and coupled numerical codes have been used fur this subject, there is discussion in Section 3 on the nature of the codes and how the content of the codes can be audited. To what extent does a particular code capture the essence of the problem in hand? Consideration is also given to the associated question of code selection and the future of numerical codes. The state-of-knowledge statements are presented in Section 4 under 11 headings which follow the repository design sequence. The overview conclusion is that A predictive THM capability is required to support repository design because precedent practice information is insufficient. Many aspects of THM processes and modelling are now well understood and there is a variety of numerical codes available to provide solutions for different host rock and repository conditions. However, modelling all the THM mechanisms in space and time is extremely complex and simplifications will have to be made - if only because it is not possible to obtain all the necessary detailed supporting information. Therefor, an important step is to clarify the THM modelling requirement within the PA context. This will help to indicate the complexity of THM modelling required and hence the models. mechanisms, type of computing, supporting data, laboratory and in situ testing, etc, required. An associated transparent and open audit trail should be developed. We also include comments from reviewers and highlight four outstanding issues which are currently being studied in the DECOVALEX III programme.

  • 24. Hudson, John A.
    et al.
    Bäckström, Ann
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Engineering Geology and Geophysics.
    Rutqvist, J.
    Jing, Lanru
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Engineering Geology and Geophysics.
    Backers, T.
    Chijimatsu, M.
    Christiansson, R.
    Feng, X. T.
    Kobayashi, A.
    Koyama, Tomofumi
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Engineering Geology and Geophysics.
    Lee, H. S.
    Neretnieks, Ivars
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Engineering.
    Pan, P. Z.
    Rinne, M.
    Shen, B. T.
    Characterising and modelling the excavation damaged zone in crystalline rock in the context of radioactive waste disposal2009In: Environmental Geology, ISSN 0943-0105, E-ISSN 1432-0495, Vol. 57, no 6, p. 1275-1297Article in journal (Refereed)
    Abstract [en]

    This paper describes current knowledge about the nature of and potential for thermo-hydro-mechanical-chemical modelling of the excavation damaged zone (EDZ) around the excavations for an underground radioactive waste repository. In the first part of the paper, the disturbances associated with excavation are explained, together with reviews of Workshops that have been held on the subject. In the second part of the paper, the results of a DECOVALEX [DEmonstration of COupled models and their VALidation against EXperiment: research funded by an international consortium of radioactive waste regulators and implementers (http://www.decovalex.com)] research programme on modelling the EDZ are presented. Four research teams used four different models to simulate the complete stress-strain curve for Avro granite from the Swedish A"spo Hard Rock Laboratory. Subsequent research extended the work to computer simulation of the evolution of the repository using a 'wall-block model' and a 'near-field model'. This included assessing the evolution of stress, failure and permeability and time-dependent effects during repository evolution. As discussed, all the computer models are well suited to sensitivity studies for evaluating the influence of their respective supporting parameters on the complete stress-strain curve for rock and for modelling the EDZ.

  • 25.
    Jing, Lanru
    KTH, Superseded Departments, Land and Water Resources Engineering.
    A review of techniques, advances and outstanding issues in numerical modelling for rock mechanics and rock engineering2003In: International Journal of Rock Mechanics And Mining Sciences, ISSN 1365-1609, E-ISSN 1873-4545, Vol. 40, no 3, p. 283-353Article, review/survey (Refereed)
    Abstract [en]

    The purpose of this review paper is to present the techniques. advances. problems and likely future developments in numerical modelling for rock mechanics. Such modelling is essential for studying the fundamental processes occurring in rocks and for rock engineering design. The review begins by explaining the special nature of rock masses and the consequential difficulties when attempting to model their inherent characteristics of discontinuousness. anisotropy, inhomogencity and inelasticity. The rock engineering design backdrop to the review is also presented. The different types of numerical models are outlined in Section 2. together with a discussion on how, to obtain the necessary parameters for the models. There is also discussion on the value that is obtained from the modelling. especially the enhanced understanding of those mechanisms initiated by engineering perturbations. In Section 3, the largest section. states-of-the-art and advances associated with the main methods are presented in detail. In many cases. for the model to adequately represent the rock reality. it is necessary to incorporate couplings between the thermal. hydraulic and mechanical processes. The physical processes and the equations characterizing the coupled behaviour are included in Section 4. with an illustrative example and discussion on the likely future development of coupled models. Finally. in Section 5. the advances and outstanding issues in the subject are listed and in Section 6 there are specific recommendations concerning quality control. enhancing confidence in the models, and the potential future developments.

  • 26.
    Jing, Lanru
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Engineering Geology and Geophysics.
    Baghbanan, Alireza
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Engineering Geology and Geophysics.
    Stress and scale effects of the hydraulic properties of fractured rocks2008In: Boundaries of rock mechanics: recent advances and challenges for the 21st century : proceedings of the International Young Scholars' Symposium on Rock Mechanics, 28 April-2 May, 2008, Beijing, China / [ed] Meifeng Cai, Jin'an Wang, 2008, p. 41-48Conference paper (Refereed)
    Abstract [en]

    The paper investigates the stress and scale effects on the hydraulic permeability of fractured rocks considering the correlation between distributed fracture aperture and trace length, where the fracture aperture and trace length follow a truncated lognormal distribution and a power-law distribution, respectively This parameter correlation of fractures leads to larger REV size and permeability magnitudes of the DEM models compared with the case of using constant apertures, which vary with stress conditions, and with the overall permeability more controlled by large-sized fractures.

  • 27.
    Jing, Lanru
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering (moved 20130630).
    Feng, X
    Main rock mechanics issues in geological disposal of radioactive wastes: Yanshilixue Yu Gongcheng Xuebao2006In: Chinese Journal of Rock Mechanics and Engineering, ISSN 1000-6915, Vol. 25, no 4, p. 833-841Article in journal (Refereed)
    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.

  • 28.
    Jing, Lanru
    et al.
    KTH, Superseded Departments, Land and Water Resources Engineering.
    Hudson, J. A.
    Fundamentals of the hydro-mechanical behaviour of rock fractures: roughness characterization and experimental aspects2004In: International Journal of Rock Mechanics And Mining Sciences, ISSN 1365-1609, E-ISSN 1873-4545, Vol. 41, no 3, p. 383-383Article in journal (Refereed)
    Abstract [en]

    The coupled hydro-mechanical behaviour of rock fractures plays an important role in design, performance and safety assessments of rock engineering projects. However, due to the complexity in the mathematical representation of the fracture surface geometry and its effects on the stress-flow behaviour of the fractures, and the limitations in the test conditions in laboratories, significant lack of knowledge still exists in testing and modelling approaches regarding rock fractures. Based on a general review of the roughness characterization and shear-flow testing of rock fractures, this paper presents the definition of the stationarity threshold of roughness, and a combined experimental-numerical approach for simulating rock fracture testing conditions for more general fluid flow behaviour of the rock fractures. The conclusions are that fracture roughness characterization must be conducted and represented in three-dimensions and the more general fluid flow behaviour cannot be observed with conventional parallel shear-flow tests or compressionradial flow tests. Numerical simulations are needed to reveal more general behaviour of stress-flow processes of rock fractures with boundary and loading conditions that are difficult or impractical in laboratory tests.

  • 29.
    Jing, Lanru
    et al.
    KTH, Superseded Departments, Land and Water Resources Engineering.
    Hudson, J. A.
    Numerical methods in rock mechanics2002In: International Journal of Rock Mechanics And Mining Sciences, ISSN 1365-1609, E-ISSN 1873-4545, Vol. 39, no 4, p. 409-427Article, review/survey (Refereed)
    Abstract [en]

    The purpose of this CivilZone review paper is to present the techniques, advances, problems and likely future development directions in numerical modelling for rock mechanics and rock engineering. Such modelling is essential for Studying the fundamental processes occurring in rock,, for assessing the anticipated and actual performance of structures built on and in rock masses, and C hence for Supporting rock engineering design. We begin by providing the rock engineering design backdrop to the review in Section 1. The states-of-the-art of different types of numerical methods are outlined in Section 2, with focus on representations of fractures in the rock mass. In Section 3, the numerical methods for incorporating couplings between the thermal, hydraulic and mechanical processes are described. In Section 4, inverse solution techniques are summarized. Finally, in Section 5, we list the issues of special difficulty and importance in the subject. In the reference Est, 'significant' references are asterisked and 'very significant' references are doubly asterisked.

  • 30.
    Jing, Lanru
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering.
    Koyama, T.
    Zhao, Z.
    Li, B.
    Stress and shear effects on fluid flow and solute transport in rock fractures2013In: Rock Characterisation, Modelling and Engineering Design Methods - Proceedings of the 3rd ISRM SINOROCK 2013 Symposium, Taylor & Francis Group, 2013, p. 33-44Conference paper (Refereed)
    Abstract [en]

    This paper provides a brief summary of a continuous research programme by the authors since 2004, and highlights the research approach, achievements and outstanding issues for conceptual understanding, laboratory testing and mathematical modeling of the coupled stress-shear-fluid flow-solute transport processes of rock fractures. The focuses are put on stress and shear induced fluid flow anisotropy, transport pass channeling, and impact of considering different retardation mechanisms in single fractures of crystalline rocks, typically granites, due to its importance for the performance and safety assessments of geological radioactive waste disposal projects.

  • 31.
    Jing, Lanru
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering.
    Min, K. -B
    Baghbanan, A.
    Zhao, Z.
    Understanding coupled stress, flow and transport processes in fractured rocks2013In: Geosystem Engineering, ISSN 1226-9328, Vol. 16, no 1, p. 2-25Article in journal (Refereed)
    Abstract [en]

    This paper presents a review of a systematic research program for understanding the scale and stress effects on the transport behaviors of fractured crystalline rocks, using a hybrid discrete element and particle tracking approach. The motivation is the importance of understanding the stress effects on the behaviors of contaminant transport in fractured crystalline rocks, which is an important issue of rock mechanics for environmental safety assessments of many rock engineering projects. The study is divided into three steps: the first step is a basic study that established the mathematical platform for deriving the conditions, criteria, basic approaches, and test case results for investigating the stress and scale effects on the hydraulic behavior of the fractured rock concerned. At the second step, based on outstanding issues drawn from the first step, the study was extended to consider the effects of the correlation between the fracture aperture and size (represented by trace length) on the permeability of the fractured rock and uncertainties in deriving equivalent continuum properties of fractured rocks. The third step added the particle/solute transport processes to the mathematical platform, including different retardation mechanisms, so that the impact of stress on safety can be directly evaluated, even though it can only be done conceptually. The obtained results show that stress, scale, and inter-parameter correlations of the fracture system geometry are dominant issues for the understanding and characterization of coupled hydro-mechanical processes of fractured rocks and play a significant role for understanding the mass transport behavior in them, with direct impact on geo-environmental safety.

  • 32.
    Jing, Lanru
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Engineering Geology and Geophysics.
    Min, Ki-Bok
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Engineering Geology and Geophysics.
    Baghbanan, Alireza
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Engineering Geology and Geophysics.
    Stress and scale-dependency of hydromechanical properties of fractured rocks2009In: Rock Mechanics: New Research / [ed] M. Abbie and J. S. Bedford, New York: Nova Science Publishers, Inc., 2009, 1, p. 109-165Chapter in book (Refereed)
  • 33.
    Jing, Lanru
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering (moved 20130630), Engineering Geology and Geophysics.
    Stephansson, O.
    Case Studies of Discrete Element Method Applications in Geology, Geophysics and Rock Engineering2007In: Fundamentals Of Discrete Element Methods For Rock Engineering: Theory And Applications, Elsevier, 2007, p. 447-538Chapter in book (Refereed)
  • 34.
    Jing, Lanru
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering (moved 20130630), Engineering Geology and Geophysics.
    Stephansson, O.
    Constitutive Models of Rock Fractures and Rock Masses - The Basics2007In: Fundamentals Of Discrete Element Methods For Rock Engineering:: Theory And Applications, Elsevier, 2007, p. 47-109Chapter in book (Refereed)
  • 35.
    Jing, Lanru
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering (moved 20130630), Engineering Geology and Geophysics.
    Stephansson, O.
    Discrete Element Methods for Granular Materials2007In: Fundamentals Of Discrete Element Methods For Rock Engineering: Theory And Applications, Elsevier, 2007, p. 399-444Chapter in book (Refereed)
  • 36.
    Jing, Lanru
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering (moved 20130630), Engineering Geology and Geophysics.
    Stephansson, O.
    Discrete Fracture Network (DFN) Method2007In: Fundamentals Of Discrete Element Methods For Rock Engineering: Theory And Applications, Elsevier, 2007, p. 365-398Chapter in book (Refereed)
  • 37.
    Jing, Lanru
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering (moved 20130630), Engineering Geology and Geophysics.
    Stephansson, O.
    Explicit Discrete Element Method for Block Systems - the Distinct Element Method2007In: Developments in Geotechnical Engineering: Fundamentals of Discrete Element Methods for Rock Engineering — Theory and Applications, Elsevier, 2007, p. 235-316Chapter in book (Refereed)
  • 38.
    Jing, Lanru
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering (moved 20130630), Engineering Geology and Geophysics.
    Stephansson, O.
    Fluid Flow and Coupled Hydro-Mechanical Behavior of Rock Fractures2007In: Fundamentals Of Discrete Element Methods For Rock Engineering: Theory And Applications, Elsevier, 2007, p. 111-144Chapter in book (Refereed)
  • 39.
    Jing, Lanru
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering (moved 20130630), Engineering Geology and Geophysics.
    Stephansson, O.
    Governing Equations for Motion and Deformation of Block Systems and Heat Transfer2007In: Fundamentals Of Discrete Element Methods For Rock Engineering: Theory And Applications, Elsevier, 2007, p. 25-46Chapter in book (Refereed)
  • 40.
    Jing, Lanru
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering (moved 20130630), Engineering Geology and Geophysics.
    Stephansson, O.
    Implicit Discrete Element Method For Block Systems - Discontinuous Deformation Analysis (DDA)2007In: Fundamentals of Discrete Element Methods for Rock Engineering — Theory and Applications, Elsevier, 2007, p. 317-364Chapter in book (Refereed)
  • 41.
    Jing, Lanru
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering (moved 20130630), Engineering Geology and Geophysics.
    Stephansson, O.
    Introduction2007In: Fundamentals of Discrete Element Methods for Rock Engineering Theory and Applications, Elsevier, 2007, p. 1-21Chapter in book (Other academic)
  • 42.
    Jing, Lanru
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering (moved 20130630), Engineering Geology and Geophysics.
    Stephansson, O.
    Numerical Techniques for Block System Construction2007In: Developments in Geotechnical Engineering Fundamentals of Discrete Element Methods for Rock Engineering — Theory and Applications, Elsevier, 2007, p. 199-232Chapter in book (Refereed)
  • 43.
    Jing, Lanru
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering (moved 20130630), Engineering Geology and Geophysics.
    Stephansson, O.
    The Basics of Combinatorial Topology for Block System Representation2007In: Fundamentals of Discrete Element Methods for Rock Engineering: Theory and Applications, Elsevier, 2007, p. 179-197Chapter in book (Refereed)
  • 44.
    Jing, Lanru
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering (moved 20130630), Engineering Geology and Geophysics.
    Stephansson, O.
    The Basics of Fracture System Characterization - Field Mapping and Stochastic Simulations2007In: Developments in Geotechnical Engineering Fundamentals of Discrete Element Methods for Rock Engineering — Theory and Applications, Elsevier, 2007, p. 147-177Chapter in book (Refereed)
  • 45.
    Jing, Lanru
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Engineering Geology and Geophysics.
    Stephansson, Ove
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Engineering Geology and Geophysics.
    Discrete methods for rock engineering-theory and application2007 (ed. 1)Book (Refereed)
  • 46. Jing, Lanru
    et al.
    Stephansson, Ove
    Fundamentals of Discrete Element Methods for Rock Engineering2007Book (Refereed)
  • 47. Jing, Lanru
    et al.
    Stephansson, Ove
    Research results from the DECOVALEX III BECHPAR Projects2005In: International Journal of Rock Mechanics And Mining Sciences, ISSN 1365-1609, E-ISSN 1873-4545, Vol. 42, no 5-6, p. 591-870Article in journal (Refereed)
  • 48. Koyama, T.
    et al.
    Jing, Lanru
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Engineering Geology and Geophysics.
    Particle mechanics approach for simulating micro-structure damage and failure processes of rock core samples due to different fluid salinity2006In: Proc. of the 2nd International Conference on Coupled T-H-M-C Processes in Geo-Systems: Fundamentals, Modeling, Experiments and Applications, GeoProc 2006, 2006, p. 569-574Conference paper (Refereed)
  • 49. Koyama, T.
    et al.
    Neretnieks, Ivars
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Engineering.
    Jing, Lanru
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Engineering Geology and Geophysics.
    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 shear2008In: International Journal of Rock Mechanics And Mining Sciences, ISSN 1365-1609, E-ISSN 1873-4545, Vol. 45, no 7, p. 1082-1101Article in journal (Refereed)
    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.

  • 50.
    Koyama, Tomofumi
    et al.
    KTH, Superseded Departments, Land and Water Resources Engineering.
    Fardin, Nader
    KTH, Superseded Departments, Land and Water Resources Engineering.
    Jing, Lanru
    KTH, Superseded Departments, Land and Water Resources Engineering.
    Shear-induced anisotropy and heterogeneity of fluid flow in a single rock fracture with translational and rotary shear displacements: a numerical study2004In: International Journal of Rock Mechanics And Mining Sciences, ISSN 1365-1609, E-ISSN 1873-4545, Vol. 41, no 3, p. 426-426Article in journal (Refereed)
    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.

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