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Rock mass response for lined rock caverns subjected to high internal gas pressure

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Journal of Rock Mechanics and Geotechnical Engineering 2023年第1期15卷 119-129页

作者： Davi Rodrigues Damasceno Johan Spross fredrik johansson Division of Soil and Rock Mechanics KTH Royal Institute of TechnologySE-10044StockholmSweden

The storage of hydrogen gas in underground lined rock caverns(LRCs)enables the implementation of the first fossil-free steelmaking process to meet the large demand for crude steel.Predicting the response of rock mass is important to ensure that gas leakage due to rupture of the steel lining does not occur.Analytical and numerical models can be used to estimate the rock mass response to high internal pressure;however,the fitness of these models under different in situ stress conditions and cavern shapes has not been studied.In this paper,the suitability of analytical and numerical models to estimate the maximum cavern wall tangential strain under high internal pressure is studied.The analytical model is derived in detail and finite element(FE)models considering both two-dimensional(2D)and three-dimensional(3D)geometries are presented.These models are verified with field measurements from the LRC in Skallen,southwestern Sweden.The analytical model is inexpensive to implement and gives good results for isotropic in situ stress conditions and large cavern heights.For the case of anisotropic horizontal in situ stresses,as the conditions in Skallen,the 3D FE model is the best approach.

关键词： Lined rock caverns(LRCs) High pressure Rock mass response In situ stress condition Cavern shape Gas storage

Modelling erosion of a single rock block using a coupled CFD-DEM approach

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Journal of Rock Mechanics and Geotechnical Engineering 2023年第9期15卷 2375-2387页

作者： Penghua Teng fredrik johansson J.Gunnar I.Hellström Division of Fluid and Experimental Mechanics Department of Engineering Sciences and MathematicsLuleåUniversity of TechnologyLuleåSE-97187Sweden Division of Soil and Rock Mechanics KTH Royal Institute of TechnologyStockholmSE-10044Sweden

Rock block removal is the prevalent physical mechanism for rock erosion and could affect the stability of dam foundations and spillways.Despite this,understanding of block removal is still inadequate because of the complex interactions among block characteristics,hydraulic forces,and erosive processes acting on the block.Herein,based on a previously conducted physical experiment of erosion of a single rock block,the removal processes of two different protruding blocks are represented by a coupled computational fluid dynamics-discrete element model(CFD-DEM)approach under varied flow conditions.Additionally,the blocks could be rotated with respect to the flow direction to consider the effect of the discontinuity orientation on the block removal process.Simulation results visualize the entire block removal process.The simulations reproduce the effects of the discontinuity orientation on the critical flow velocity inducing block incipient motion and the trajectory of the block motion observed in the physical experiments.The numerical results present a similar tendency of the critical velocities at different discontinuity orientations but have slightly lower values.The trajectory of the block in the simulations fits well with the experimental measurements.The relationship between the dimensionless critical shear stress and discontinuity orientation observed from the simulations shows that the effect of block protrusion becomes more dominant on the block incipient motion with the increase of relative protrusion height.To our knowledge,this present study is the first attempt to use the coupled finite volume method(FVM)-DEM approach for modelling the interaction behavior between the block and the flowing water so that the block removal process can be reproduced and analyzed.

关键词： Rock erosion Block removal Incipient motion Coupled CFD-DEM Critical shear stress

Influence of location of large-scale asperity on shear strength of concrete-rock interface under eccentric load

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Journal of Rock Mechanics and Geotechnical Engineering 2020年第3期12卷 449-460页

作者： Dipen Bista Gabriel Sas fredrik johansson Leif Lia SINTEF Narvik As Narvik8517Norway Norwegian University of Science and Technology(NTNU) Trondheim7491Norway Royal Institute of Technology(KTH) Stockholm10044Sweden

The location and geometry of large-scale asperity present at the foundation of concrete gravity dams and buttress dams affect the shear resistance of the concrete-rock interface.However,the parameters describing the frictional resistance of the interface usually do not account for these asperities.This could result in an underestimate of the peak shear stre ngth,which leads to significantly conservative design for new dams or unnecessary stability enhancing measures for existing ones.The aim of this work was to investigate the effect of the location of first-order asperity on the peak shear strength of a concrete-rock interface under eccentric load and the model discrepancy associated with the commonly used rigid body methods for calculating the factor of safety(FS)against sliding.For this,a series of direct and eccentric shear tests under constant normal load(CNL)was carried out on concrete-rock samples.The peak shear strengths measured in the tests were compared in terms of asperity location and with the predicted values from analytical rigid body methods.The results showed that the large-scale asperity under eccentric load significantly affected the peak shear strength.Furthermore,unlike the conventional assumption of sliding or shear failure of an asperity in direct shear,under the effect of eccentric shear load,a tensile failure in the rock or in the concrete could occur,resulting in a lower shear strength compared with that of direct shear tests.These results could have important implications for assessment of the FS against sliding failure in the concrete-rock interface.

关键词： Shear strength Concrete-rock interface Asperity location Eccentric load Model discrepancy Dam foundation

Effects of spatial variation in cohesion over the concrete-rock interface on dam sliding stability

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Journal of Rock Mechanics and Geotechnical Engineering 2015年第6期7卷 659-667页

作者： Alexandra Krounis fredrik johansson Stefan Larsson Division of Soil and Rock Mechanics KTH Royal Institute of Technology

The limit equilibrium method （LEM） is widely used for sliding stability evaluation of concrete gravitydams. Failure is then commonly assumed to occur along the entire sliding surface simultaneously.However, the brittle behaviour of bonded concrete-rock contacts, in combination with the varying stressover the interface, implies that the failure of bonded dam-foundation interfaces occurs progressively. Inaddition, the spatial variation in cohesion may introduce weak spots where failure can be initiated.Nonetheless, the combined effect of brittle failure and spatial variation in cohesion on the overall shearstrength of the interface has not been studied previously. In this paper, numerical analyses are used toinvestigate the effect of brittle failure in combination with spatial variation in cohesion that is taken intoaccount by random fields with different correlation lengths. The study concludes that a possible existenceof weak spots along the interface has to be considered since it significantly reduces the overallshear strength of the interface, and implications for doing so are discussed.

关键词： Concrete gravity dam Sliding stability Cohesion Brittle failure Spatial variation

Tailor-Made Electrospun Culture Scaffolds Control Human Neural Progenitor Cell Behavior—Studies on Cellular Migration and Phenotypic Differentiation

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Journal of Biomaterials and Nanobiotechnology 2017年第1期8卷 1-21页

作者： Ulrica Englund-johansson Eitan Netanyah fredrik johansson Department of Clinical Sciences in Lund Division of Ophthalmology Lund University Lund Sweden Department of Biology Section Functional Zoology Lund University Lund Sweden

In neuroscience research, cell culture systems are essential experimental platforms. It is of great interest to explore in vivo-like culture substrates. We explored how basic properties of neural cells, nuclei polarization, phenotypic differentiation and distribution/migration, were affected by the culture at poly-L-lactic acid (PLLA) fibrous scaffolds, using a multipotent mitogen-expanded human neural progenitor cell (HNPC) line. HNPCs were seeded, at four different surfaces: two different electrospun PLLA (d = 1.2 - 1.3 μm) substrates (parallel or random aligned fibers), and planar PLL- and PLLA surfaces. Nuclei analysis demonstrated a non-directed cellular migration at planar surfaces and random fibers, different from cultures at aligned fibers where HNPCs were oriented parallel with the fibers. At aligned fibers, HNPCs displayed the same capacity for phenotypic differentiation as after culture on the planar surfaces. However, at random fibers, HNPCs showed a significant lower level of phenotypic differentiation compared with cultures at the planar surfaces. A clear trend towards greater neuronal formation at aligned fibers, compared to cultures at random fibers, was noted. We demonstrated that the topography of in vivo-resembling PLLA scaffolds significantly influences HNPC behavior, proven by different migration behavior, phenotypic differentiation potential and nuclei polarization. This knowledge is useful in future exploration of in vivo-resembling neural cell system using electrospun scaffolds.

关键词： Human Stem Cells PLLA Electrospinning Differentiation Migration

Pain and fatigue in adult patients with rheumatoid arthritis: Association with body awareness, demographic, disease-related, emotional and psychosocial factors

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Open Journal of Nursing 2013年第2期3卷 293-300页

作者： Helena Loof Unn-Britt johansson Elisabet Welin Henriksson Staffan Lindblad fredrik Saboonchi Sophiahemmet University StockholmSweden Karolinska Institutet Department of Clinical SciencesDanderyd HospitalDivision of MedicineStockholmSweden Karolinska Institutet Division of NursingDepartment of Neurobiology and Rheumatology UnitKarolinska HospitalStockholmSweden Karolinska Institutet Department of Learning InformaticsManagement and EthicsStockholmSweden Karolinska Institutet Department of NeuroscienceDivision of Insurance MedicineStockholmSweden University of Stockholm Stress Research InstituteStockholmSweden Red Cross University College StockholmSweden

Background: Patients and clinicians report pain and fatigue as key outcome measures in rheumatoid arthritis. Fatigue and pain are a major concern to patients. Aim: The objective of this study was to examine fatigue and pain in adult patients with rheumatoid arthritis (RA) and to investigate the association between pain and fatigue with body awareness, demographic, disease-related, emotional and psychosocial factors. Method: Data were collected from a sample of patients with RA (n = 120) recruited from a Rheumatology clinic in a large university hospital in Stockholm, Sweden. Eligible for inclusion were patients between 20 -80 years of age and with a confirmed diagnosis of RA. Fatigue was measured using the Multidimensional Assessment of Fatigue (MAF) scale, while the Visual Analogue Scale (VAS) was used to assess components of pain. A multiple stepwise regression analysis was performed to evaluate factors related to fatigue and pain. In the first step a univariate analysis of variance (ANOVA) was used for all relevant independent factors. In the next step backwards stepwise regression was applied. Result: Fatigue was significantly associated with the Disease Activity Score 28-joints (DAS 28) (p = 0.049), the Body Awareness Questionnaire (BAQ) (p = 0.006), the Positive Affect (PA) scale (p = 0.008) and no smoking (p = 0.021). Pain was significantly associated with the EuroQol EQ-5D (p = 0.008) and the DAS 28 (p = 0.001). The adjusted R-square was 28.6% for fatigue and 50.0% for pain. Conclusion: This study clearly demonstrates that fatigue and pain in patients with RA appear to be associated with disease-related factors. Furthermore, fatigue was related to body awareness and emotional factors, and pain was related to health related quality of life.

关键词： Pain Fatigue Emotional Psychosocial Rheumatoid Arthritis

MARE研究项目1999～2006:关于项目管理的思考

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AMBIO－人类环境杂志 2007年第2期36卷 115-118页

作者： Sif johansson fredrik Wulff Erik Bonsdorff 王胜（译）徐化成（校） Swedish Environmental Protection Agency S-10648 Stockholm Sweden Department of Systems Ecology Stockholm University SE 106 91 Stockholm Sweden Abo Akademi University Environmental and Marine Biology Akademigatan 1 FI-20500 Turku/AboFinland 不详

引言至少从20世纪80年代开始，波罗的海的富养化就引起了波罗的海地区国家的极大关注。1988年，在赫尔辛基委员会的部长级会议上，部长们同意在10年内将波罗的海的养分总输入削减50％。1998年，部长们认为，尽管1988年的会议启动了若干... 详细信息

引言至少从20世纪80年代开始，波罗的海的富养化就引起了波罗的海地区国家的极大关注。1988年，在赫尔辛基委员会的部长级会议上，部长们同意在10年内将波罗的海的养分总输入削减50％。1998年，部长们认为，尽管1988年的会议启动了若干行动，但并未达到50％的目标，富养化仍然受到极大关注。他们还表态要开发共同合作研究项目，其中包括决策支持模型。

关键词：项目管理部长级会议波罗的海合作研究项目决策支持模型赫尔辛基委员会极大

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科学的挑战——重视成本效益,清洁波罗的海

AMBIO－人类环境杂志 2001年第4期30卷 254-259页

作者： fredrik Wulff Erik Bonsdorff Ing-Marie Gren Sif johansson Anders Stigebrandt 祁冬梅斯德哥尔摩大学 Abo学院大学瑞典农业大学瑞典哥德堡大学

波罗的海是世界上受人类活动影响最严重的海洋之一,虽然有减少向波罗的海排放营养物质的国际协议,但迄今为止采取的措施,既没有从根本上减少营养物质的排放,也没有促进环境的改善。部分原因可以归咎为缺少有关物理学、生物地球化学和生... 详细信息

波罗的海是世界上受人类活动影响最严重的海洋之一,虽然有减少向波罗的海排放营养物质的国际协议,但迄今为止采取的措施,既没有从根本上减少营养物质的排放,也没有促进环境的改善。部分原因可以归咎为缺少有关物理学、生物地球化学和生态特性之间大尺度关系和相互作用的知识,但是还缺少全流域范围的成本效益分析。错误的决策非常危险,例如,执行的减少排放的方案根本没有效果,或远远达不到成本效益。许多学科的研究者正面临着一个共同的挑战:开发一个决策支持系统,作为整个波罗的海成本效益分析法的科学基础。研究项目海洋富营养化的研究(MARE)(http://www.***.su.se)正致力于这方面的研究。

关键词：成本效益分析波罗的海海洋污染海洋富营养化