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  • 1.
    Shamu, John
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Zou, Liangchao
    Håkansson, Ulf
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics. Skanska Sweden AB.
    An experimental study of 2D radial flow of a yield stress fluid between parallel disks2019In: September 2-3, 2019, Helsinki. Nordic Grouting Symposium 2019, Helsinki: Nordic Grouting Symposium , 2019Conference paper (Refereed)
  • 2.
    Zou, Liangchao
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Resources, Energy and Infrastructure.
    Håkansson, Ulf
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics. Skanska AB, Stockholm.
    Cvetkovic, Vladimir
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Resources, Energy and Infrastructure.
    Cement grout propagation in 2D fracture networks: impact of rheology2019In: Proceedings in Earth and Geosciences: Rock Mechanics for Natural Resources and Infrastructure Development / [ed] Sergio A.B. da Fontoura, Ricardo Jose Rocca, José Pavón Mendoza, CRC Press, 2019, Vol. 6, p. 2486-2493Conference paper (Refereed)
    Abstract [en]

    Cement grouts propagation into a two-dimensional water-saturated fracture networks with different values of rheological properties are simulated by using an extended two-phase flow model. The cement grouts are typical non-Newtonian fluids that contain yield stress, which are often assumed as Bingham fluids. The aim of this study is to investigate the impact of Bingham rheological properties, i.e. yield stress and plastic viscosity, on cement gouts propagation in two-dimensional fracture networks. The results generally show that the rheological properties of cement grouts, i.e. yield stress and plastic viscosity, significantly affect cement grouts propagation in the fracture network. The propagation rate in the fracture networks reduces with the increase of the yield stress and the plastic viscosity of the cement grouts.

  • 3.
    Shamu, John
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Zou, Liangchao
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Resources, Energy and Infrastructure.
    Håkansson, Ulf
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics. Skanska Sweden AB.
    Cementbaserade Injekteringsmedels Reogram: Instabilt Flöde Och Inverkan På Injektering2019In: Proceedings Bergdagarna 2019, Stockholm, 2019Conference paper (Other academic)
  • 4.
    Wersäll, Carl
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Åkesson, Fredrik
    Persson, Andreas
    Dynamic roller characteristics and CCC using automatic frequency control2019Conference paper (Refereed)
  • 5.
    Damasceno, Davi Rodrigues
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Spross, Johan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Johansson, Fredrik
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Johansson, Jan
    Naturgasteknik.
    Efficiency of subset simulation in the design of lined rock caverns for storage of hydrogen gas2019In: Proceedings of the 13th International Conference on Applications of Statistics and Probability in Civil Engineering, Seoul, South Korea, 2019, article id 124Conference paper (Refereed)
    Abstract [en]

    Efforts to substitute the use of fossil fuels in industry by hydrogen gas requires the storage of large volumes of gas with a reliable pressure vessel design. The Hydrogen Breakthrough Ironmaking Technology (HYBRIT) initiative aims to make the whole steel making process in Sweden fossil-free with the storage of industrial scale quantities of hydrogen in underground Lined Rock Cavers (LRCs). The LRC concept is a relatively new design methodology that can be further developed with respect to safety and economic efficiency and reliability-based design methods provide one option to comply with codes and regulations. High reliability is required for the storage of hydrogen gas and the computational time becomes unpractical for the evaluation of a complex system such as the LRC. In this paper, the efficiency of Subset Simulation (SuS) regarding accuracy, precision and required number of samples is studied for the calculation of probability of failure against fatigue of the steel lining. It can be observed that by increasing the number of samples per level and increasing the conditional probability of failure the precision increases as well as the total number of samples. The accuracy of the SuS is checked with respect to Monte Carlo simulation (MCS) showing good agreement and with greater precision for fewer number of samples. A case study is performed for the geologic conditions of Sweden showing that the considered failure mode is unlikely for high stresses and good rock mass quality.

  • 6.
    Olsson, Lars
    et al.
    Geostatistik AB.
    Spross, Johan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Hintze, Staffan
    NCC.
    Stille, Håkan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Båtelsson, Olle
    Trafikverket.
    Framtidens riskhantering – nu med systemförståelse2019Conference paper (Other (popular science, discussion, etc.))
    Abstract [sv]

    Geoteknikern hanterar i sin vardag många och ofta stora risker. Men trots att kostnaden för negativa utfall av geotekniska risker årligen bedöms ligga på flera miljarder kronor, används tillgängliga verktyg för strukturerad riskhantering sparsamt. I ett SBUF-projekt har vi tagit fram en vägledning för hur sådana verktyg kan användas i praktiken. Vi har i denna vägledning särskilt fokuserat på den för riskhanteringen så viktiga systemförståelsen av det geotekniska sammanhanget som man verkar i. Denna artikel är en sammanfattande kortversion av den slutrapport som författarna skrivit inom ramen för SBUF-projektet.

  • 7.
    Spross, Johan
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Stille, Håkan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Johansson, Fredrik
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Palmström, Arild
    Rock Mass AS.
    Hur ska bergbyggande kunna inkluderas i Eurokod 7: How to include rock engineering in Eurocode 72019In: Proceedings Bergdagarna 2019, 2019Conference paper (Other (popular science, discussion, etc.))
    Abstract [en]

    Sweden, among other countries, has chosen not to apply Eurocode 7 to rock engineer­ing design. However, Eurocode 7 is currently under revision, with one purpose being to improve its applicability to rock engineering. Such a revision would however require that the code accommodates the current principles of rock engineering design and exe­cution, since rock engineering in many cases fundamentally differs from other types of construction. In this presentation, we give our view on how a design code for rock engineering needs to be organized, in order to ensure that new rock engineering struc­tures become both sufficiently safe and cost-effectively constructed. An important pre­requisite is having a decision-theoretical connection between design and risk manage­ment that always should permeate geotechnical design and construction. The presented research is based on the results from a research project funded by the Rock Engineering Research Foundation (BeFo) that was finalized in January 2019.

  • 8.
    Zou, Liangchao
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Resources, Energy and Infrastructure.
    Håkansson, Ulf
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics. Skanska AB .
    Cvetkovic, Vladimir
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Resources, Energy and Infrastructure.
    Non-Newtonian grout flow in single rough-walled rock fractures2019Conference paper (Refereed)
    Abstract [en]

    Modeling of cement grout flow in rock fractures plays an important role in the design of rock grouting. Cement grouts used in rock grouting practice are typical non-Newtonian fluids containing yield stress, and are often assumed as Bingham fluids. Natural rock fractures typically consist of rough surfaces. Therefore, in reality, rock grouting process actually involves non-Newtonian fluid flow in rough-walled fractures, which is rarely studied in the literature. In this work, we focus on the impact of surface roughness and present direct numerical simulations of non-Newtonian grouts flow in single rough-walled fractures, using a regularized method to approximate the yield-stress. The rough-walled rock fracture models are created from a laser-scanned surface of a granite rock sample, to represent realistic features of natural rock fractures. The numerical results generally show nonlinear behaviors of non-Newtonian fluid flow in rough-walled fractures. The surface roughness significantly reduces the effective transmissivity when Reynolds number is relatively large. The obtained result can be used for upscaling analysis in practice, in order to reduce the potential uncertainties caused by the surface roughness of the rock fractures.

    The full text will be freely available from 2020-01-01 23:22
  • 9.
    Stille, B.
    et al.
    Department of Civil Infrastructure, AECOM Nordic AB, Stockholm, Sweden.
    Johansson, Fredrik
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics. Department of Civil Infrastructure, AECOM Nordic AB, Stockholm, Sweden.
    Ríos Bayona, Francisco
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics. Department of Civil Infrastructure, AECOM Nordic AB, Stockholm, Sweden.
    Batres Estrada, R.
    Department of Civil Infrastructure, AECOM Nordic AB, Stockholm, Sweden.
    Roslin, M.
    Swedish Transport Administration, Stockholm, Sweden.
    Stockholm bypass project – passage under the Lake Mälaren2019In: Tunnels and Underground Cities: Engineering and Innovation meet Archaeology, Architecture and Art- Proceedings of the WTC 2019 ITA-AITES World Tunnel Congress (WTC 2019), May 3-9, 2019, Naples, Italy / [ed] Daniele Peila, Giulia Viggiani, Tarcisio Celestino, London: CRC Press, 2019, p. 1569-1578Conference paper (Refereed)
    Abstract [en]

    In the last years, the Swedish Transport Administration has been working on improving and expanding road communications in Sweden. The Stockholm Bypass Project, one of the biggest projects in Swedish history, consists of a 21 km long highway that goes around the city from north to south. In order to reduce the environmental impact, 17 km of the total length will be excavated underground passing through several regional fault zones and subsea passages. One of the most difficult technical challenges in this project is the passage under the Lake Mälaren and the regional fault zone in the Fiskar fjord. This paper presents the utilized methodology to design the temporary rock support and to manage the risks and uncertainties for the excavation through the fault zone, which mainly originate from the limited information about the rock conditions and the relatively large width of the tunnels.

  • 10.
    Ríos Bayona, Francisco
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Stigsson, Martin
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Resources, Energy and Infrastructure. SKB, Swedish Nuclear Fuel and Waste Management Co.
    Johansson, Fredrik
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Mas Ivars, Diego
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics. SKB, Swedish Nuclear Fuel and Waste Management Co.
    Comparison between shear strength based on Barton’s roughness profiles and equivalent synthetic profiles based on fractal theory2018In: 52nd U.S. Rock Mechanics/Geomechanics Symposium, American Rock Mechanics Association (ARMA) , 2018Conference paper (Refereed)
    Abstract [en]

    A comprehensive understanding of the shear strength and the mechanical behavior of rock joints is to some extent still missing today. Several attempts have been made to develop empirical and analytical shear strength criteria that explain this mechanism. One of the most important parameters governing the shear strength of rock fractures is the surface roughness, which is generally determined using the Joint Roughness Coefficient (JRC). This parameter is often determined subjectively in the field by comparison with 10 predefined roughness profiles. Recent studies indicate that surface roughness can be accurately represented by using fractal analysis. The aim of this study is to perform a first attempt to investigate the mechanical equivalence in terms of the peak shear strength between synthetic rock fractures, where the surface roughness has been generated using fractal theory, and standard roughness profiles from Barton and Choubey, 1977, using the particle flow code PFC2D. The results from the numerical shear tests under constant normal load (CNL) are compared with the predicted peak shear strength using Barton’s criterion and a back-calculation of the JRC value is carried out.

  • 11. Davy, P.
    et al.
    Darcel, C.
    Le Goc, R.
    Munier, R.
    Selroos, J. O.
    Ivars, Diego Mas
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    DFN, why, how and what for, concepts, theories and issues2018In: 2nd International Discrete Fracture Network Engineering Conference, DFNE 2018, American Rock Mechanics Association (ARMA), 2018Conference paper (Refereed)
    Abstract [en]

    DFN – Discrete Fracture Network – is primarily a modeling framework for fractured geological systems that aims to integrate field data into simulations of flow and/or deformation. It is complementary to, or competing with, continuum methods with both advantages of easily integrating the statistical properties of fracture networks, and of not assuming any homogenization scale. The core element is the DFN conceptual model, which makes a functional link between data from different sources, prior knowledge and medium models. We discuss some fundamental issues about this conceptual model, namely (i) the upscaling of small-scale measurements to site-scale relationships, (ii) intrinsic variability versus geological determinism, (iii) the way to incorporate a priori knowledge, (iv) the transformation of a statistical description into a medium model, (v) the critical characteristics (length scales, scaling laws or physical properties) of fractures for a given DFN application. The main product of the DFN conceptual model is medium models, whose role is to extrapolate/interpolate data with a faithful representation of the geological system. The way in which fracture correlations are taken into account, or not, in the generation process plays an important control on the connectivity and flow properties of medium models.

  • 12.
    Hov, Sölve
    et al.
    Geomind AB.
    Eriksson, Håkan
    Geomind AB.
    Wersäll, Carl
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Dynamic Compaction of Rockfill on Land and under Water at Stockholm Norvik Port2018Conference paper (Refereed)
  • 13.
    Zou, Liangchao
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Resources, Energy and Infrastructure.
    Cvetkovic, Vladimir
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Resources, Energy and Infrastructure.
    Jing, Lanru
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering.
    Ivars, Diego Mas
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Impact of Normal Stress Caused Closure on Fluid Flow and Solute Retention in Rock Fractures2018Conference paper (Refereed)
    Abstract [en]

    Modeling of coupled hydro-mechanical and chemical (HMC) processes in fractured rocks is an important topic for many geoengineering projects.  Over the past decades, many efforts have been devoted to study the flow and transport in single fractures with consideration of mechanical effects. It is generally known that the mechanical effects, i.e. normal and shear deformation, significantly affect fluid flow and solute transport processes in rough-walled rock fractures since the deformation may largely alter the structure of fracture apertures that directly controls transmissivity. Due to complicated physical processes combined with complexity of geometry structures, many issues remain open questions, such as fracture surface roughness characterization, deformation dependence of transmissivity and advective transport in natural rock fractures. In this work, we attempt to investigate the impact of stress caused closure on fluid flow and solute advective transport in a rough-walled fracture through numerical modeling.  A rough-walled fracture model is created based on a laser-scanned rock surface. The Bandis’s model is used to describe the fracture closure subject to normal stress. The flow is modeled by solving Reynolds equation and the advective transport is simulated through Lagrangian particle tracking. The results show that the normal stress caused fracture closure creates asperity contacts and reduces the mean aperture, which significantly reduces transmissivity, and affects the travel time and transport resistance. With increases of normal stress, the specific surface area reduces nonlinearly due to the nonlinear closure. In practice, especially for important hydrogeological projects, e.g. nuclear waste disposal, it is important to consider the coupled HMC processes in design and risk assessment.

  • 14.
    Zou, Liangchao
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Resources, Energy and Infrastructure.
    Håkansson, Ulf
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Cvetkovic, Vladimir
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Resources, Energy and Infrastructure.
    Modeling of rock grouting in saturated variable aperture fractures2018In: Proceedings of Bergdagarna 2018., 2018, p. 79-87, article id 10Conference paper (Refereed)
    Abstract [en]

    Modeling and analysis of cement grouts flow in rock fractures is important in the design, execution and monitoring of grouting in fractured rocks. At present, modeling of rock grouting mainly relies on analytical models, e.g., the real time grouting control (RTGC) method. In the RTGC method, it is assumed that the rock fractures are consisting of smooth parallel plates or disks and water flow is neglected. However, in reality, the natural rock fractures are commonly consisting of complex rough-walled surfaces and are filled with groundwater; therefore, grouting is actually a multiphase (non-Newtonian grouts and groundwater) flow process in rough-walled rock fractures with variable apertures. In this study, we present an efficient one-dimensional (1D) numerical model for modeling of rock grouting in a single rock fracture with consideration of multiphase flow and variable apertures. It is assumed that the cement grouts are Bingham fluids and that the analytical solution for flowrate with a given pressure gradient in a pair of smooth parallel plates is locally applicable. A time-dependent advection equation is used to describe the interface (between the grout and groundwater) propagation. A finite element method (FEM) code is developed to iteratively solve the mass balance and the interface advection equations. The numerical simulations are compared with the RTGC method. It generally shows that water flow significantly affect grouts penetration in the fracture, especially for the grouts with relatively lower viscosity. The variable aperture significantly postpones the penetration process compared with that of constant aperture. This numerical model is able to describe more realistic physical processes and geometry conditions in rock grouting, which can be readily used in practice to reduce the potential uncertainties in application of simplified analytical models.

  • 15. Darcel, C.
    et al.
    Davy, P.
    Le Goc, R.
    Ivars, Diego Mas
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Rock mass effective properties from a DFN approach2018In: 2nd International Discrete Fracture Network Engineering Conference, DFNE 2018, American Rock Mechanics Association (ARMA) , 2018Conference paper (Refereed)
    Abstract [en]

    Rock mass mechanical properties are strongly controlled by the fractures they contain. Their determination raises strong issues for many rock-engineering applications, like underground repository safety assessment, support design, slope stability or mine caving. To compensate the impossibility to perform direct in-situ measures of these properties at appropriate scales, empirical approaches classically aim to determine the rock mass equivalent properties from simple indicators. Here we propose an approach based on the complete representation of the rock mass as an intact rock with a population of discrete fractures through it (the Discrete Fracture Network). The core of the approach is the definition, at the rock mass scale, of the deformation induced by each fracture locally, including the fracture mechanical and geometrical parameters, the remote stress conditions and the interactions with the rest of the fracture population. Depending on the conditions, the resulting scaling and anisotropic effects can be critical. The method is applied to the Forsmark site in Sweden. We show that two main scaling regimes occur, where the shift from the one to the other is controlled by the ratio between the intact rock modulus, the typical fracture stiffness and the DFN size distribution. Beyond the scaling issue we quantify the resulting level of anisotropy. 

  • 16.
    Wersäll, Carl
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Nordfelt, Ingmar
    Larsson, Stefan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Roller compaction of rock-fill with automatic frequency control2018In: Proceedings of the Anniversary Symposium – 40 Years of Roller Integrated Continuous Compaction Control (CCC), 2018Conference paper (Refereed)
  • 17.
    Johansson, Fredrik
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Westberg Wilde, Marie
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Krounis, Alexandra
    KTH, School of Architecture and the Built Environment (ABE).
    Spross, Johan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Ríos Bayona, Francisco
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Some recent developments in reliability based slidingstability assessments for concrete dams2018In: 26th International Congress on Large Dams, 2018, CRC Press/Balkema , 2018, p. 1277-1294Conference paper (Refereed)
    Abstract [en]

    In this paper, a reliability based framework for the assessment of sliding stability for concrete dams was presented. The framework consists of several parts based on the Probabilistic model code for concrete dams developed by Westberg-Wilde and Johansson and includes guidelines on how reliability based sliding stability assessment should be performed, together with recent work by Krounis et al. how to account for partially bonded interfaces. In the proposed framework, the assessments start with performing preliminary calculations using a priori assumptions on parameters included in the analysis. If cost-benefit analyses show that further analyses could be beneficial, investigations are undertaken on relevant parameters in the failure modes. The results from the investigations are used to update the calculations in the assessment and decisions on stability enhancing measures are undertaken if necessary. In the presented example the preliminary sliding stability analysis of the interface, before testing was performed, showed a reliability index of 4.91, indicating an unacceptable failure probability of the dam without any testing. Taking into account the information obtained from testing the basic friction angle of the interface increased the reliability index from 4.91 to 7.24, clearly showing the gain of including test results in the assessment. When the influence of cohesion was accounted for a reliability index of 6.49 was obtained, which shows that cohesion can give a potential gain to the stability, even though it in this case still is lower than the gain from updating the basic friction angle. When both limit states of the interface were considered as a system the reliability index increased to 8.1.

  • 18.
    Abbaszadeh Shahri, Abbas
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Spross, Johan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Johansson, Fredrik
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Larsson, Stefan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Storskalig kartering av skredbenägenhet i västra Götaland med artificiell intelligens2018Conference paper (Other academic)
  • 19. Massarsch, Rainer
    et al.
    Wersäll, Carl
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Vibratory plate resonance compaction2018In: Proceedings of the Anniversary Symposium – 40 Years of Roller Integrated Continuous Compaction Control (CCC), 2018Conference paper (Refereed)
  • 20. Massarsch, K. Rainer
    et al.
    Wersäll, Carl
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Acoustic soil and rock sounding2017Conference paper (Refereed)
  • 21.
    Nejad Ghafar, Ali
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Sadrizadeh, Sasan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Fluid and Climate Technology.
    Draganović, Almir
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics. Lawrence Berkeley National Laboratory.
    Johansson, Fredrik
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Håkansson, Ulf
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Larsson, Stefan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Application of Low-Frequency Rectangular Pressure Impulse in Rock Grouting2017In: Grouting 2017: Grouting, Drilling, and Verification / [ed] Byle, MJ Johnsen, LF Bruce, DA ElMohtar, CS Gazzarrini, P Richards, TD, American Society of Civil Engineers (ASCE), 2017, Vol. 2, no 288, p. 104-113Conference paper (Refereed)
    Abstract [en]

    In order to sufficiently seal an underground facility in fractured rock, it is essential to obtain adequate grout spread into the surrounding fractures. The grout spread itself depends on parameters, the most significant of which are the filtration tendency and rheological properties. These properties can be affected by the applied pressure. High-frequency oscillating pressure has been shown to improve grout spread by virtue of reducing the grout viscosity. However, this method has not yet been industrialized due to the quick dissipation of the oscillation along a fracture. In a recent investigation, we examined a low-frequency rectangular pressure-impulse using a short slot. The results showed significant improvements in the injected grout volume in comparison to the static pressure results. In this paper, we examine the method in a considerably longer artificial fracture in order to investigate the dissipation of the pressure impulses. The study indicates the potential of the method to improve the grout spread in rock grouting.

  • 22.
    Ignat, Razvan
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Baker, Sadek
    Skanska.
    Liedberg, Sven
    Skanska.
    Larsson, Stefan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Djupstabilisering med kalkcementpelarskivor för förstärkning av djupa schakter2017Conference paper (Other academic)
  • 23.
    Stille, Håkan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Geological Uncertainties in Tunnelling - Risk Assessment and Quality Assurance2017In: Sir Muir Wood Lecture 2017, The International Tunnelling and Underground Space Association , 2017Conference paper (Refereed)
    Abstract [en]

    Risk is always present in rock tunnelling. The uncertainties connected to design and execution, especially geological uncertainties, are larger and to some degree different from those in other types of civil engineering projects. This implies that systems for handing the uncertainties like ISO 31 000 “Risk management –Principles and guidelines” must be adapted to the special conditions prevailing in underground projects. Risk management is, consequently, closely connected to project management. The work can be carried out in different ways in relation to the complexity of the project. However, site organizations with teams responsible for the geotechnical and geological follow-up is an important part of risk management in tunnelling. The project manager must have the overall responsibility.

    The uncertainties have to be treated as an integrated part with a set of activities within the project work and the ordinary project organization. Project models like Props, developed by Ericsson Infocom based on tollgates and milestones, are also very adequate.

    The base for risk evaluation should be the epistemic nature of geological uncertainties. Updating by observation and investigation can reduce the uncertainties. Systematic approaches for collecting additional information should be implemented. Lead-time to make adequate decisions may be obtained by identifying and looking for warning bells. In many situations such an approach will prevent unwanted events, like tunnel collapse, high water ingress and similar problems from happening.

    Rock design is affected by geological uncertainties. Models and material properties of the rock mass will have a much higher degree of uncertainty than other building material like concrete and steel. This implies that verification of the design cannot only be built on calculations as normal in civil engineering. The observational approach in tunnelling will therefore in most cases be mandatory and can be regarded as part of the risk assessment and quality control. A common approach in tunnel design is the adoption of prescriptive measures. Application of rock classification systems belongs to this category. The limitations of such approach need to be understood in order to achieve an adequate risk treatment.

    The overall quality is governed by two factors “doing the right things” and “doing the things right”. The special focus on the first issue comes from the special uncertainties connected to underground works. The system is called “Dual quality system”. Geotechnical category as defined in the new Euro Code (EC7) is an essential part in applying a dual quality system but it has to be adapted to rock engineering problems.

    The above described approach for risk assessments and quality assurance in rock engineering and tunnelling is based on experiences from tunnel projects and supported by theories of uncertainties.

  • 24.
    Draganović, Almir
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Nejad Ghafar, Ali
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Issues in Measurements and Evaluation of Penetrability of Cement-Based Grout Measured with Filter Pump and Penetrability Meter in the Field2017In: Grouting 2017, American Society of Civil Engineers (ASCE), 2017, Vol. 2, no 288 GSP, p. 404-414Conference paper (Refereed)
    Abstract [en]

    Grouting of underground constructions is important to decrease water inflow into constructions. It is therefore important to use grout with good penetration ability to achieve this goal. The purpose of this paper is to show issues connected to measuring of the penetration ability of cement-based grouts in the field with a filter pump and penetrability meter and show the need for improvement or use of some other method. Three main reasons which contribute to a different estimated critical aperture with these two methods are: different maximum test volume in regression analysis of measured data, limited maximum test volume in the filter pump, and different test pressure. Test volume should be related to volume of designed grout spread in the critical aperture and test pressure should be related to grout spread velocity in the field.

  • 25. Swindell, Robert
    et al.
    Johansson, Fredrik
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Kjellström, Ingrid
    ÅF Consult.
    Benhalimi, Mehdi
    Karaktärisering av bergmassor – systematiska fel och möjliga åtgärder2017In: / [ed] Eva Friedman, 2017Conference paper (Other academic)
    Abstract [en]

    Rock mass quality assessment is performed in a variety of situations by engineers andgeologists during design and excavation of rock engineering projects. The results form thebasis for rock engineering design and are an important part of the tender documents andcontract for rock engineering works. Trafikverket sponsored two Masters Theses to analyzethe occurrence and possible causes of systematic “errors” introduced during rock masscharacterization. This paper provides a summary of the results of these theses and shows thatthere are clear indications that systematic “errors” are introduced due to the methods used forrock mass characterization. The paper also provides suggestions for how these errors can bemitigated in future projects. Possible remedial measures include the introduction of guidelinesfor drill core logging, incorporation of geotechnical baseline reports, better coupling of rockmass characterization and rock engineering design, implementation of guidelines forexcavation mapping and continued statistical analysis of rock mass characterization data.

  • 26.
    Sjölander, Andreas
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Bjureland, William
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Ansell, Anders
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    On failure probability in thin irregular shotcrete shells2017In: Proceedings of the World Tunnel Congress 2017, 2017Conference paper (Refereed)
    Abstract [en]

    Tunnels through hard jointed rock are commonly reinforced with a combination of fibre reinforced shotcrete (sprayed concrete), FRS, and rock bolts. The design of such reinforcement is a complex task. First, the interaction between rock bolts, FRS and rock should be considered. Secondly, a natural variation in important parameters such as thickness of the shotcrete, fracture energy, and bond strength between shotcrete and rock exists. In this paper, a numerical framework for non-linear analyses of FRS suitable for Monte Carlo simulations is presented. As a case study, a 2D FE-model of a bolted shotcrete lining subjected to load from a pushing block was used to perform a sensitivity analysis for the variation in thickness. Results indicate that an irregular shotcrete thickness highly affects the failure load but has a smaller impact on ductility.

  • 27.
    Prästings, Anders
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Larsson, Stefan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Müller, Rasmus
    Tyréns AB.
    Optimizing geotechnical site-investigations2017In: Proceedings of the 19th International Conference on Soil Mechanics and Geotechnical Engineering, Seoul 2017, 2017, p. 639-642Conference paper (Refereed)
    Abstract [en]

    One major question to deal with in the process of updating the current version of Eurocode 7 is how to convert thequality of a performed site-investigation into a measurable context. This should, in turn, affect the safety factor applied to the soil-strength properties in a limit state. This paper presents a study in which the total uncertainty from the evaluation of undrained shearstrength in clay is assessed from single and multiple site-investigation methods with regard to both random and systematicuncertainties. A Bayesian procedure is used to convert potential reduction of random and systematic uncertainties into a measurablecontext in relation to: (1) the type of site-investigation method, (2) the combination of methods, and (3) the number of measurementsperformed.

  • 28. Harrison, J. P.
    et al.
    Alejano, L.
    Bedi, A.
    Ferrero, A. M.
    Lamas, L.
    Mathier, J. -F
    Migliazza, R.
    Olsson, R.
    Perucho, A.
    Sofianos, A.
    Stille, Håkan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Virely, D.
    Wittke, M.
    Rock engineering design and the evolution of Eurocode 7: The critical six years to 20202017In: 13th ISRM International Congress of Rock Mechanics, International Society for Rock Mechanics , 2017Conference paper (Refereed)
    Abstract [en]

    In 2010, the Eurocode for Geotechnical Design, EN-1997-1:2004 (CEN, 2004), informally known as Eurocode 7 or EC7, became the Reference Design Code (RDC) for geotechnical design - including rock engineering design - within the European Union (EU). EC7 is one standard within the comprehensive Structural Eurocode suite, which as a whole has been also adopted by a number of other countries beyond the EU. EC7 is thus becoming a key design standard for geotechnical engineering worldwide. As part of the Structural Eurocode suite, EC7 requires designs to adhere to the principles of Limit State Design. However, it is not clear that current rock engineering design practice can satisfy this requirement. In addition, evidence is accumulating that EC7 is currently difficult to apply to, and may even be inappropriate for, rock engineering design. These issues may be due to the fact that the development of EC7 to date took place without any formal input from the international rock mechanics and rock engineering community. In early 2011 under the auspices of CEN (Comité Européen de Normalisation / European Committee for Standardisation), EC7 entered a formal period of maintenance which was aimed at improving the applicability and ease-of-use of the Code. This maintenance cycle will conclude in 2020 with the publication of a revised version of EC7. This paper describes a number of critical aspects for rock engineering in the context of EC7, in particular the following: - the history of the Structural Eurocodes and the concepts they embody; - the nature of Limit State Design and the challenges and opportunities it poses for rock engineering design; - the formal means by which the Structural Eurocode maintenance cycle proceeds; - the plans currently being developed for improving EC7 with regard to rock engineering design and construction; - the unique and vital opportunity for the entire international rock mechanics and rock engineering community to comment on the Code and make suggestions for its improvement.

  • 29.
    Larsson, Stefan
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Spross, Johan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Bjureland, William
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Ignat, Razvan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Tar byggherrar geotekniska risker på allvar?2017Conference paper (Other (popular science, discussion, etc.))
    Abstract [en]

    During the fall of 2015, the state owned property company Akademiska hus started the construction of a new education building on KTH:s Campus. Due to the astounding and poor management of geotechnical risks during construction, we have in two previous papers discussed our observations and the built in system error that we consider exists. In this paper, we go deeper into more technical questions and present the process that we ran parallel to the construction with responsible authorities and Akademiska hus. As can be seen in the paper, property developers, such as Akademiska hus, flaws symptomatically in their management of geotechnical risks simultaneously as responsible authorities acts neglectfully. The paper brings a serious lack of competence in light which must be scrutinized and treated with urgency.

  • 30.
    Spross, Johan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Vilken roll har observationsmetoden i framtidens bergbyggande?2017Conference paper (Other (popular science, discussion, etc.))
    Abstract [en]

    In 2016, BeFo’s research project Observational method and reliability analysis wascompleted. The aim of this PhD project was to investigate how the observationalmethod can be linked to reliability-based design and when that is applicable. The resultshowed that reliability-based design methods are well adapted to apply together withthe observational method, in particular when such methods are combined with decisionanalysis. The main reason is that reliability-based methods straightforwardly canaccount for the effect of increased knowledge gained from measurements and observations.The decision analysis allows comparison of design options and design methods,so the most favourable method can be chosen. In this paper, I briefly present the mainresearch contributions of the project and discuss the future prospects of the observationalmethod.

  • 31.
    de Frias Lopez, Ricardo
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Ekblad, Jonas
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Highway Engineering Laboratory.
    Silfwerbrand, Johan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    A Numerical Study on the Permanent Deformation of Gap-Graded Granular Mixtures2016In: Proceedings of the Third International Conference on Railway Technology: Research, Development and Maintenance / [ed] J. Pombo, Stirlingshire, UK: Civil-Comp Press , 2016Conference paper (Refereed)
    Abstract [en]

    Permanent deformation accumulation of unbound granular layers under traffic plays a critical role in the performance and need for maintenance of pavements and railway structures. In this paper, the discrete element method is used to study the permanent strain behaviour of binary mixtures of elastic spheres, as an idealization of gap-graded mixtures, under triaxial monotonic loading. The effects of stress level and soil fabric structure, based on a recently proposed classification system founded on micromechanical considerations, are assessed by subjecting mixtures with varying fines contents to different stress levels. Additionally, mixtures are loaded to static failure to study the dependency of the permanent strains on the closeness of the applied stress to failure stress, in accordance with existing empirical models. Numerical results are also compared with the experimentally determined behaviour of granular materials. The findings indicate that numerical mixtures are able to reproduce some of the most significant features observed in laboratory tests on granular materials, further encouraging the use of numerical simulations to enhance the understanding of granular media behaviour. Additionally, a good correlation between fabric structure and performance is obtained, giving additional support to the use of the studied fabric classification system for performance characterization.

  • 32. Rafi, J. Y.
    et al.
    Johansson, Fredrik
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Stiiie, Håkan
    Choice of pumping pressure in pre-grouting in scandinavian tunneling projects2016In: ITA-AITES World Tunnel Congress 2016, WTC 2016, Society for Mining, Metallurgy and Exploration , 2016, p. 124-134Conference paper (Refereed)
  • 33.
    Bjurström, Henrik
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Gudmarsson, Anders
    Ryden, Nils
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Starkhammar, Josefin
    Comparative Seismic Laboratory and Non-Contact Field Measurements of Asphalt Concrete2016In: 2016 Structural Materials Technology Paper Summaries / [ed] American Society for Nondestructive Testing, 2016Conference paper (Refereed)
    Abstract [en]

    Non-contact acoustic field measurements are performed on a newly built highway to characterize the real part of the dynamicmodulus of the asphalt concrete (AC) top layer. The in situ measurements are performed using an array of 48 micro-electromechanicalsystem (MEMS) sensors. Cores extracted from the field measurement positions are then examined in a laboratory usingseismic modal testing for comparison. The laboratory testing allows master curves to be constructed to characterize the AC over awide temperature and frequency range. It is demonstrated that the real parts of the dynamic moduli are consistent at the fieldtemperatures using the two test methods. The in situ measurements are also shown to be highly repeatable. The presentedcomparative study indicates a possible application for assuring the quality of AC based on mechanical properties using fast noncontactin situ measurements.

  • 34.
    Dinegdae, Yared H.
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Birgisson, Björn
    Aston University, UK.
    Design inputs variabilities influence on pavement performance reliability2016In: Functional Pavement Design / [ed] Erkens et al. (Eds), 2016, p. 741-750Conference paper (Refereed)
    Abstract [en]

    Pavement design is a probabilistic process as it involves many random variables.Through the incorporation of reliability, pavement design methods consider inputparameters variabilities effect on pavement performance. Load and Resistance Factor Design(LRFD) is a typical example of reliability-based design procedure. In LRFD, a set of partialsafety factors are developed by modelling input parameters variabilities with representativeaverage conditions. This paper evaluates the impact input parameters variabilities have onestimated target reliability in the case when actual variabilities are different from assumedconditions. This was achieved by evaluating a field pavement section with various combinationsof input parameters variabilities. The optimized section for a given target reliability wasachieved through the mechanics-based LRFD procedure and the actual reliabilities of thevarious cases were obtained using a methodology that uses response surface approach andfirst order reliability method (FORM). The results have shown that the level of input parametersvariabilities used affect the target reliability considerably.

  • 35.
    Wersäll, Carl
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Larsson, Stefan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Influence of force ratio and frequency on vibratory surface compaction2016In: Geotechnics for Sustainable Infrastructure Development / [ed] Phung Duc Long, 2016Conference paper (Refereed)
  • 36.
    Kardan, Caesar
    et al.
    Ramböll, Sweden.
    Viking, Kenneth
    NCC, Sweden.
    Nik, Leila
    Geosigma, Sweden.
    Larsson, Stefan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Influence of operator performance on quality of CPTu results2016In: Challenges in Nordic Geotechnic, The Icelandic Geotechnical Society , 2016, p. 153-158Conference paper (Refereed)
    Abstract [en]

    Cone penetration tests (CPT) is one of the most sophisticated geotechnical field investigations methods. As for all test methods, the CPT is associated with many uncertainties. However,there are two main sources that have aninfluence on the quality ofCPTumeasurements. One is the choice of equipment since different equipment differs in design and functionality.The other source relates tooperator performanceand incorrectexecutionof the methodas well as lack of competence to analyze the results.However, inorder to achieve satisfying results, the operator should be skilled, competent and well-educated. Some countries don’t have any formal education and in countries wereformal education doexist, the achieved quality ofresultsdoesquite frequentlystill come out unsatisfactory.This fact is seldom mentioned, but still a well-known fact amongst practicing geotechnicians.The objective of this paperis to discuss operator performance related factors and contribute to a better knowledgeof how important every single procedure contributes to the outcome as well as quality of the results.

  • 37.
    Hellgren, Rikard
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Malm, Richard
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Johansson, Fredrik
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Ríos Bayona, Francisco
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Pull-out tests of 50-year old rock bolts2016In: Proceedings of the International Symposium on Appropriate technology to ensure proper Development, Operation and Maintenance of Dams in Developing Countries, Johannesburg, 2016, p. 263-272, article id 258Conference paper (Refereed)
    Abstract [en]

    In this paper, detailed numerical and analytical calculations are presented with the aim to study the effect of rock bolts and the influence of degradation on the dam safety. In addition, results from inspections and pull-out tests are presented from a case study with rock bolts that has been installed for 50 years. All tested bolts have with margin withstood higher stresses than the maximum allowed stresses according to Swedish standards. At visual inspection, no bolts have shown any major signs of degradation and all investigate bolts are in very good condition.

  • 38.
    Malm, Richard
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Johansson, Fredrik
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Fransson, Lennart
    Luleå Tekniska Universitet.
    Alternative methods to determine the ice load on concrete dams2015Conference paper (Other academic)
  • 39.
    Ghazal, Rima
    et al.
    Itasca .
    Mas Ivars, Diego
    Itasca.
    Johansson, Fredrik
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Batres-Estrada, Rocio
    SWECO Civil AB.
    Back analysis of in situ stress at shallow depth using discontinuum numerical modeling - a case study at the Odenplan station in Stockholm, Sweden2015Conference paper (Refereed)
  • 40.
    Larsson, Stefan
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Kock-Larsen, Jennie
    Golder Associates AB.
    Garin, Håkan
    GeoVerkstan Sverige AB.
    Ekström, Jan
    The Swedish Transport Administration.
    Correlation between Undrained Shear Strength in Dry Deep Mixing Columns and Unimproved Soft Soil2015In: Proceedings of the Deep Mixing 2015 Conference / [ed] Al Sehn; Mary Ellen Large; Paolo Marzano; Hidenori Takahashi, Deep Foundation Institute , 2015, p. 573-580Conference paper (Refereed)
    Abstract [en]

    This paper describes the testing procedure (or protocols) for quality control of dry deep mixing columns in a major ground improvement project carried out in Sweden. Quality control was mainly based on column penetration tests performed at different stages in the project and on two occasions after installation. In the paper, the results from the tests are compared with tests on the unimproved clay. As expected, the results show that the correlation between undrained shear strength in the columns and in the unimproved soft soil depends mainly on the in-situ stress. However, the correlation probably depends on when the tests were performed after mixing. When the influence of the in-situ stress was excluded from the analysis, no significant correlation could be identified. This means that the undrained shear strength in the columns and in the unimproved soft can be considered to be uncorrelated when the strengths and the corresponding variability are evaluated with depth from groups of tests.

  • 41.
    Bjurström, Henrik
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Rydén, Nils
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Effect of Surface Unevenness on In Situ Measurements and Theoretical Simulation in Non-Contact Surface Wave Measurements Using a Rolling Microphone Array2015In: NDT-CE2015 proceedings, Berlin: NDT , 2015Conference paper (Refereed)
    Abstract [en]

    Non-destructive seismic testing using air-coupled microphones is today an attractive alternative to the more conventional stationary accelerometer testing, in order to perform fast and reliable material characterization on pavement structures. A multichannel microphone array enables fast mobile data collection using a rolling trolley. It is essential that the microphone array and the material surface are perfectly aligned to receive a correct result. This study presents estimations of the calculation errors due to misalignments between the microphone array and the material surface. It is shown that even small misalignments can cause large errors. A realistic pavement roughness is simulated in order to quantify the errors in different situations and for different materials (stiffness). A simple solution to correct the errors under certain circumstances is also presented.

  • 42.
    Bjurström, Henrik
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Rydén, Nils
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Effect of surface unevenness on non-contact surface wave measurements using a rolling microphone array2015In: 41ST ANNUAL REVIEW OF PROGRESS IN QUANTITATIVE NONDESTRUCTIVE EVALUATION: Volume 34 / [ed] Dale E Chimenti and Leonard J. Bond, American Institute of Physics (AIP), 2015, Vol. 1650, p. 128-135Conference paper (Refereed)
    Abstract [en]

    Surface wave velocity is measured and evaluated along a straight survey line in order to compare two different data acquisition methods. Results from a rolling microphone array are compared to data acquired using a conventional accelerometer. Results from the two different data acquisition methods are shown to be similar. However, it is demonstrated that the results are very sensitive to misalignments between the microphone array and the measured surface. Practices to overcome problems with misalignments are discussed and demonstrated.

  • 43.
    Johansson, Fredrik
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Ekström, I.
    Rito Pi, C.
    Malm, Richard
    Carlsson, V.
    FEM-analysis of a concrete dam in northern Sweden2015In: Association of State Dam Safety Officials, Dam Safety 2015, Association of State Dam Safety Officials , 2015Conference paper (Refereed)
    Abstract [en]

    Krångfors is a concrete dam located in northern Sweden that was constructed in three stages from 1928 to 1973. This expansion in different stages resulted in a complicated structural design. Extensive cracks have been noticed in parts of the structure. Two main hypotheses for the cause of these cracks were initially established; 1) alkali-silica reaction (ASR) and 2) large temperature variations in the structure. Petrographic analyses of concrete cores showed that the concrete ballast consisted of greywacke with potential for ASR. However, accelerated testing of concrete cores showed that the potential for expansion due to ASR was limited. To analyze the effect from temperature variations, three dimensional FEManalyses were performed. The results from these FEM-analyses are the main focus of this paper. These analyses showed that adding the annual temperature variation and possible shrinkage to the FEM-model gave results that could explain the observed cracks.

  • 44.
    Ignat, Razvan
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Baker, Sadek
    Larsson, Stefan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Field test of braced excavation supported wth rows of dry deep mixing columns2015In: Proceedings of the Deep Mixing 2015 Conference, Deep Foundation Institute , 2015, p. 573-580, article id 2079Conference paper (Refereed)
  • 45.
    Spross, Johan
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Johansson, Fredrik
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Larsson, Stefan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Observationsmetoden – hur svårt kan det vara?2015Conference paper (Other academic)
  • 46.
    Wersäll, Carl
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Optimering av packningsparametrar för vibrationsvältar2015Conference paper (Other academic)
    Abstract [sv]

    Jordpackning av bankar och fyllning utförs normalt med vibrationsvält i olika typer av anläggningsprojekt. I ett doktorandprojekt vid KTH studeras hur denna process kan effektiviseras genom att optimera vissa packningsparametrar. Huvuddelen av projektet syftar till att finna den optimala vibrationsfrekvensen. Omfattande småskaleförsök har utförts i laboratorium som visar att frekvensen har stort inflytande över packningseffektiviteten. Fullskaleförsök kommer att visa om och hur dessa resultat kan implementeras i praktiken. Inom projektet har även en beräkningsmodell utvecklats som enkelt kan förutsäga den dynamiska responsen av en vibrerande platta på markytan. Projektet finansieras av Svenska Byggbranschens Utvecklingsfond (SBUF), Dynapac Compaction Equipment AB, Trafikverket, PEAB och Fredrik Bachmans minnesfond.

  • 47.
    Bjureland, William
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Spross, Johan
    KTH, School of Architecture and the Built Environment (ABE).
    Johansson, Fredrik
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Stille, Håkan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Some aspect of reliability-based design for tunnels using observational method (EC7)2015In: EUROCK 2015 & 64th Geomechanics Colloquium, Salzburg, 2015Conference paper (Refereed)
    Abstract [en]

    According to Eurocode 7, the observational method is an accepted design method, where a preliminary design may be updated as the construction progresses. However, Eurocode 7 does not give any advice on how to relate the observations to the acceptable level of safety of the structure. In this paper, we outline a methodology for how to use deformation measurements to predict the final deformation of a circular rock tunnel to calculate the probability of failure. Consequently, the measurements can be used to verify that the design does not violate the specified safety level. The paper shows the potential of combining the observational method with reliability-based design in tunneling

  • 48.
    Vestberg Wilde, Marie
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Johansson, Fredrik
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Suggested probabilistic model code for probability-based assessment of concrete dams2015In: ICOLD 25th Congress/ICOLD 83rd Annual Meeting/Symposium Hydropower 15, 2015Conference paper (Other academic)
    Abstract [en]

    For design and assessment of concrete dams the standard procedure is to calculate safety factors and compare with some experience-based requirements. Probability-based design and assessment is still in its infancy, but in recent years an increasing number of papers has been presented in different contexts, e.g. ICOLD (2009), 3IWRDD (2011). This paper describes the background and main contents of a suggested “probabilistic model code for concrete dams” that gives recommendations on how to perform probabilistic analysis of concrete gravity and buttress structures. The purpose of the work is to educate dam owners, consultants and researchers in Sweden and to, in the long-term, implement probability-based guidelines and, if found appropriate, partial factors. In this paper, some of the most important points in the PMCD are described and an example is given on the use. The main conclusion from the work is that the code enables probabilistic analyses and also comparisons of dams. When several dams are analyzed using similar assumptions, for their specific context, the resulting comparison will become a useful tool to identify the necessary remedial works.

  • 49.
    Westberg Wilde, Marie
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Johansson, Fredrik
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Suggested probabilistic model code for probability-based assessment of concrete dams2015Conference paper (Other academic)
  • 50.
    Deckner, Fanny
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Viking, Kenneth
    NCC Construction, Stockholm, Sweden.
    Hintze, Staffan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics. NCC Construction, Stockholm, Sweden.
    Vibration transfer during vibratory sheet pile driving: a full-scale field test2015In: Proceedings of the 6th International Conference on Earthquake Geotechnical Engineering, ICEGE , 2015Conference paper (Refereed)
    Abstract [en]

    Vibration transfer between sheet pile and soil during vibratory driving is commonly modelled using theory developed for impact pile driving. However, field observations and previous literature show that a driven sheet pile vibrates both vertically and horizontally. A transfer of vibrations to adjoining sheet piles in the sheet pile wall can also be observed. Results from a full-scale field test are presented showing that driven sheet piles vibrate both horizontally as well as vertically and that vibrations to a high degree are transferred to adjoining sheet piles. Based on the results it is suggested that the common vibration transfer model is modified to better capture the real behavior of the driven sheet pile and the adjoining sheet pile wall.

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