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  • 51.
    Larsson, Stefan
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Bergman, Niclas
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Probabilistic design of dry deep mixing using an observational approach2015In: Ground Improvement, ISSN 1365-781X, E-ISSN 1751-7621, Vol. 168, no 4, p. 300-311Article in journal (Refereed)
    Abstract [en]

    The evaluation of material parameters for design should consider the spatial variability of measured parameters, the extent and type of tests, and the type and size of the current mechanical system. This is stated in Eurocode 7; however, there is very little guidance as to how this is to be done in practice. The strength and deformation properties of dry deep mixing columns are subject to high variability, and it is difficult to estimate these parameters in advance. Owing to this high variability, probabilistic analyses are considered useful for the design and quality assessment decision procedure. This paper presents a procedure, based on probabilistic analysis, which is a combination of design by calculation and the observational method. The procedure renders the possibility to update acceptance criteria based on measurements during construction, and the methodology rewards the development of the mixing process and increased testing.

  • 52.
    Larsson, Stefan
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Broms, Bengt
    Shear box model tests with lime/cement columns -some observations of failure mechanisms2000In: GeoEng 2000, 2000, p. CD-Rom-6pConference paper (Refereed)
    Abstract [en]

    In this paper, the behaviour of lime/cement columns under lateral loading has been examined by performing five shear box model tests. Tests were conducted with singular lime/cement columns and with rows of columns with and without screw anchors. The lime/cement columns were installed in the shear box by mixing dry lime and cement in place with soft clay. The results show that single lime/cement columns do not contribute greatly to the shear resistance in the direct shear zone. The rows of columns increased the shear resistance considerably. The test results also show that the shear resistance of the rows of columns can be increased further by using screw anchors. The paper discusses the various failure mechanisms observed.

  • 53.
    Larsson, Stefan
    et al.
    KTH.
    Broms, Bengt B.
    Shear box model tests with lime/cement columns - Some observations of failure mechanisms2018In: ISRM International Symposium 2000, IS 2000, International Society for Rock Mechanics , 2018Conference paper (Refereed)
    Abstract [en]

    In this paper, the behaviour of lime/cement columns under lateral loading has been examined by performing five shear box model tests. Tests were conducted with singular lime/cement columns and with rows of columns with and without screw anchors. The lime/cement columns were installed in the shear box by mixing dry lime and cement in place with soft clay. The results show that single lime/cement columns do not contribute greatly to the shear resistance in the direct shear zone. The rows of columns increased the shear resistance considerably. The test results also show that the shear resistance of the rows of columns can be increased further by using screw anchors. The paper discusses the various failure mechanisms observed.

  • 54.
    Larsson, Stefan
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Charbit, Benjamin
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Malm, Richard
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Ansell, Anders
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Pilotstudie för utveckling av förenklad beräkningsmetod för jordstabilisering med skivor av kalkcementpelare2011Report (Other academic)
  • 55.
    Larsson, Stefan
    et al.
    Tyréns AB.
    Dahlström, Marcus
    Nilsson, Bengt
    A complementary field study on the uniformity of lime-cement columns for deep mixing2005In: Ground Improvement, ISSN 1365-781X, E-ISSN 1751-7621, Vol. 9, no 2, p. 67-77Article in journal (Refereed)
    Abstract [en]

    This paper presents results from work concerning development of the installation technique of lime-cement columns for ground improvement by deep mixing, as a part of the work of the Swedish Deep Stabilization Research Centre. A second field test was performed in order to test the findings from a previous work published by Larsson et al. The same methodology was adopted as in the previous work. However, the experimental programme was somewhat modified. Statistical analysis of variances, ANOVA, was used to investigate the influence of a number of factors in the mixing process: retrieval rate; number of mixing blades; rotation speed; air pressure in the binder tank; and diameter of the binder outlet hole. The analysis was performed with respect to the stabilisation effect and the coefficient of variation evaluated from hand-operated penetrometer tests on excavated column sections in open test pits. The retrieval rate and the number of mixing blades were found to have a significant effect. The effect of rotation speed, the binder tank air pressure, and the diameter of the outlet hole were insignificant. The two field studies illustrate the importance of performing a sufficient number of tests when studying influencing factors, because the strength is highly stochastic with large variations.

  • 56.
    Larsson, Stefan
    et al.
    Tyréns AB, Stockholm, Sweden.
    Dahlström, Marcus
    Nilsson, Bengt
    Uniformity of lime-cement columns for deep mixing: A field study2005In: Ground Improvement, ISSN 1365-781X, E-ISSN 1751-7621, Vol. 9, no 1, p. 1-15Article in journal (Refereed)
    Abstract [en]

    A field study of the mixing process of lime-cement columns for deep mixing has been carried out at a test site in Håby, Sweden. The study aimed to investigate the influence on the stabilisation effect and the coefficient of variation for excavated columns, when a number of factors related to the installation process were varied. The influencing factors investigated were the retrieval rate, number of mixing blades, rotational speed, air pressure in the storage tank, and diameter of the binder outlet hole. A large number of hand-operated penetrometer tests were carried out on the excavated column cross-sections. Statistical multifactor analyses were used to evaluate the influence on the stabilisation effect and the coefficient of variation of the varied factors. The results showed that the retrieval rate and the number of mixing blades were found to have a significant effect. The effect of rotational speed and the diameter of the outlet hole were found to be insignificant. The field study showed that the strength and deformation properties of the soil and the upper pair of mixing blades, with respect to the binder outlet hole, had a major influence on the binder dispersion over the column cross-section. The blade rotation number can be used as an indirect value of the mixing work and can be used as a measure of the mixing tool effectiveness.

  • 57.
    Larsson, Stefan
    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.
    Spross, Johan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Wersäll, Carl
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Geotekniker och bergmekaniker ska lära för livet: men hur ska det gå till?2014In: Bygg & teknik, ISSN 0281-658X, no 1, p. 70-72Article in journal (Other (popular science, discussion, etc.))
    Abstract [sv]

    Geoteknikeroch bergmekaniker ska ha förmågan att projektera, bygga och underhålla geokonstruktionerför det moderna samhället. Konstruktionerna måste vara både ekonomiska, säkra,estetiska och miljövänliga. Ingenjören får sin kompetens genom utbildning,träning och erfarenheter från skolan, annan fortbildning och arbete iprojekten. Kraven på en bred kunskapsbas ökar alltmer, samtidigt som det krävsen betydande fördjupning inom det specifika ämnesområdet. Både högskolorna ochnäringslivet genomgår nu ett påtagligt generationsskifte och det är därförlämpligt att inom de närmaste åren utföra en omfattande didaktisk analysavseende: Vad ska läras ut? Varför ska det läras ut? Hur ska det läras ut? Förvem ska det läras ut? Vi anser att geoteknik­ och bergmekanikundervisningen börinriktas på att ge ingenjören förmågor som ska utgöra en bas för ett livslångtlärande.

  • 58.
    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.

  • 59.
    Larsson, Stefan
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Kosche, Mirja
    A laboratory study on the transition zone around lime-cement columns2005In: Proceedings of the International Conference on Deep Mixing: Best Practice and Recent Advances, 2005, p. 111-118Conference paper (Refereed)
  • 60.
    Larsson, Stefan
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Malm, Richard
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Ansell, Anders
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Numerisk simulering av lateralt belastade kalkcementpelare2012In: Bygg & teknik, ISSN 0281-658X, no 1, p. 25-28Article in journal (Other (popular science, discussion, etc.))
  • 61.
    Larsson, Stefan
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Malm, Richard
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Charbit, Benjamin
    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.
    Finite element modelling of laterally loaded lime-cement columns using a damage plasticity model2012In: Computers and geotechnics, ISSN 0266-352X, E-ISSN 1873-7633, Vol. 44, p. 48-57Article in journal (Refereed)
    Abstract [en]

    The behaviour of laterally loaded lime-cement columns in a shear box was studied. Laboratory tests are presented together with numerical analyses where the columns are simulated by a concrete damage plasticity model that considers stiffness degradation. Seven model tests were investigated where the columns were installed in a single column pattern and in rows with different column overlap in order to investigate the influence of the degree of overlapping of the columns in the rows. The results of the numerical evaluations showed good agreement with the experimental shear stress-displacement relation and a good accuracy with respect to the fractures developed.

  • 62.
    Larsson, Stefan
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Nilsson, Amelie
    Horizontal Strength Variability in Lime-Cement Columns2009In: Proc. of the Int. Symp. on Deep Mixing & Admixture Stabilizaton / [ed] Masaki Kitazume, Masaaki Terashi, Sachihiko Tokunaga, Nobushige Yasuoka, SANWA CO.,LTD , 2009, p. 629-634Conference paper (Other academic)
  • 63.
    Larsson, Stefan
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Nilsson, Gunnar
    NCC.
    Jelisic, Nenad
    Trafikverket.
    Utveckling av Jb-Totalsondering för kontroll av kc-pelare2018Report (Other academic)
  • 64.
    Larsson, Stefan
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Nilsson, Lars
    Findings of the work on influencing factors on the installation process for lime-cement columns2005In: Proceedings of the International Conference on Deep Mixing: Best Practice and Recent Advances, 2005, p. 561-569Conference paper (Refereed)
  • 65.
    Larsson, Stefan
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Rehnman, Sven-Erik
    Walter, Maria
    Laboratory method for design and development ofthe dry jet mixing method1999In: Geotechnical Engineering for Transportation Infrastructure: Theory and Practice, Planning and Design, Construction and Maintenance / [ed] F.B.J. Barends, J. Lindenberg, H.J. Luger, A. Verruijt, L. de Quelerij, CRC Press, 1999, p. 1533-1538Conference paper (Refereed)
  • 66.
    Larsson, Stefan
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Rothhämel, Mirja
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Jacks, Gunnar
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering (moved 20130630).
    A laboratory study on strength loss in kaolin surrounding lime-cement columns2009In: Applied Clay Science, ISSN 0169-1317, E-ISSN 1872-9053, Vol. 44, no 1-2, p. 116-126Article in journal (Refereed)
    Abstract [en]

    This study evaluated property changes in laboratory-prepared kaolin surrounding lime-cement columns. The parameters investigated included geotechnical parameters such as undisturbed undrained shear strength, remoulded shear strength, water content, and Atterberg limits. In addition the exchangeable Ca2+, Na+ and K+ ion concentrations were assessed. Four types of small-scale lime-cement columns were manufactured using different production methods and binder blending ratios. Tests were performed 7, 14, 30 and 90 days after installation. The migration of Ca2+, Na+ and V ions from the lime-cement columns into the surrounding soil has been confirmed through the chemical analysis on a large number of samples taken. The results illustrate that the undrained shear strength properties in the surrounding kaolin were significantly affected by the migration of Ca2+, Na+ and K+ ions. An increase in the Na+ and K+ ion concentrations in the front of the migrated Ca2+ ions was observed. The tests illustrate that, under the experimental conditions chosen, the remoulded undrained shear strength decreased in a thin zone as a result of the migrated Na+ and K+ ions. The magnitude of the strength loss depended on the binder blending ratio in the lime-cement columns.

  • 67.
    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.
    Obefintlig tillsyn utarmar geoteknisk kompetens hos husbyggare2017In: Bygg & teknik, ISSN 0281-658X, no 1, p. 61-63Article in journal (Other (popular science, discussion, etc.))
  • 68.
    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.

  • 69.
    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 husbyggare geoteknisk säkerhet på allvar?2016In: Samhällsbyggaren, ISSN 2000-2408, no 3, p. 30-31Article in journal (Other (popular science, discussion, etc.))
    Abstract [en]

    Sedan 1 januari 2011 ska standarden Eurokod 7 användas för att garantera geotekniska konstruktioners säkerhet. Efter att på nära håll ha följt ett pågående husprojekt ifrågasätter vi nu hur väl uppföljningen av pågående grundläggnings- arbeten för byggnader fungerar. Hur lätt ska det vara att strunta i säkerheten — och komma undan med det utan konsekvenser?

  • 70.
    Larsson, Stefan
    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.
    Olsson, Lars
    On horizontal variability in lime-cement columns in deep mixing2005In: Geotechnique, ISSN 0016-8505, E-ISSN 1751-7656, Vol. 55, no 1, p. 33-44Article in journal (Refereed)
    Abstract [en]

    The variability with respect to results from hand-operated penetrometer tests on lime-cement column cross-sections is investigated by means of spatial correlation structures. Experimental directional semi-variograms are evaluated for a large number of column cross-sections from two field tests. Analyses of variance (ANOVA) are performed in order to investigate the influence of various factors in the installation process on the inherent variability. The paper also briefly discusses the concept of sufficient mixing: the link between the mixing process and the mechanical system. The results have been interpreted within the framework of variance reduction based on an averaging model for axially loaded columns. The results from the two field tests show that the radius is the dominating variable in the variability, and different types of correlation structure can be obtained in spite of the fact that they have been equally installed. The mechanical mixing work does not significantly influence the type of spatial correlation structure. Furthermore, a simple design consideration shows that the variance reduction has a major influence on the determination of the partial factor of safety.

  • 71.
    Larsson, Stefan
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Torstensson, Bengt-Arne
    Sjödahl, Thord
    Väg 73, Infartsled Nynäshamn - Avanceraddjupstabilisering med vertikaldränering2001In: Väg- och Vattenbyggaren, no 4, p. 44-48Article in journal (Other (popular science, discussion, etc.))
  • 72.
    Larsson, Stefan
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Wallmark, Göran
    Förbelastning för två höga järnvägsbankar påBotniabanan2001In: Bygg & teknik, ISSN 0281-658X, Vol. 93, no 1, p. 41-46Article in journal (Other (popular science, discussion, etc.))
  • 73.
    Lingwanda, Mwajuma
    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.
    Nyaoro, Dalmas L.
    Inherent soil variability linked to different characterization methods2014Conference paper (Other academic)
  • 74.
    Lingwanda, Mwajuma
    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.
    Nyaoro, D.L.
    Correlations of SPT, CPT and DPL data for sandy soil in Tanzania2015In: Geotechnical and Geological Engineering, ISSN 0960-3182, E-ISSN 1573-1529, Vol. 33, no 5, p. 1221-1233Article in journal (Refereed)
    Abstract [en]

    In Tanzania, standard penetration test (SPT) is the most commonly used in situ test for foundation design site investigations. In an effort to increase the amount of geotechnical information at low cost, the quicker and much cheaper dynamic probing of light (DPL) hammer is sometimes performed along with SPT to supplement the expensive SPT. Nevertheless, the information gathered with DPL has been applicable only for site stratification. Recently, the static cone penetration test (CPT) has also been introduced in the country with a view to combining these methods in site investigations. In this study, side by side testing was performed with the three in situ methods and correlations established through regression analysis and arithmetic mean methods. Results indicate that DPL data correlate better with CPT than SPT data, with lower magnitudes of transformation uncertainty. The local SPT–CPT correlations compare fairly well to those in the literature. The established correlations extend the function of DPL data to analysis and design.

  • 75.
    Lingwanda, Mwajuma
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Prästings, Anders
    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.
    Nyaoro, Dalmas L.
    Comparison of geotechnical uncertainties linked to different soil characterization methods2016In: Geomechanics and Geoengineering, ISSN 1748-6025, E-ISSN 1748-6033, p. 1-15Article in journal (Refereed)
    Abstract [en]

    One of the essential inputs in settlement prediction models is the soil modulus, which may be obtained from laboratory tests or estimated from in situ measurements. The total uncertainty in predicting the confined modulus of a sandy soil is quantified with data from side-by-side in situ testing using the standard penetration test, the static cone penetration test, the light dynamic probing and the laboratory oedometer test. To estimate transformation errors, correlations are proposed between in situ and laboratory data. The results indicate that similar magnitudes of total uncertainties are associated with the in situ methods, which are approximately twice as high as those from the direct oedometer method. The quantified uncertainties are an important input for reliability-based designs of foundations under similar soil conditions.

  • 76.
    Müller, Rasmus
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Larsson, Staffan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Veda trial embankment-comparison between measured and calculated deformations and pore pressure development2009In: GEOTECHNICS OF SOFT SOILS - FOCUS ON GROUND IMPROVEMENT / [ed] Karstunen M, Leoni M, BOCA RATON: CRC PRESS-TAYLOR & FRANCIS GROUP , 2009, p. 405-410Conference paper (Refereed)
    Abstract [en]

    The Veda embankment is about 300 metres long, up to 16 metres high and is being built as a staged construction on vertically drained subsoil consisting of very loose post glacial sulphide clay and very loose glacial clay. The Veda trial embankment was built one year in advance in order to obtain essential knowledge about the behaviour of the subsoil when subjected to an embankment load. This paper present and discuss the process of using the measurements from the trial embankment together with laboratory tests in order to establish a numerical analysis for the Veda embankment, that describes the behaviour of the soil sufficiently well as a foundation for the design and prediction according to the observational method.

  • 77.
    Müller, Rasmus
    et al.
    Tyréns AB.
    Larsson, Stefan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Aspects on the modelling of smear zones around vertical drains2013In: Proceedings of the 18th International Conference on Soil Mechanics and Geotechnical Engineering, Paris 2013, 2013, p. 2965-2968Conference paper (Refereed)
    Abstract [en]

    The analytical design of vertical drains in soft clay requires knowledge of the coefficient of consolidation and also of the disturbance effects induced during the installation of the drains. Several analytical models describing the disturbance effects in different ways are proposed in the literature. The earliest and simplest models describe the disturbance effect in terms of concentric cylinders around a drain where a reduced and constant permeability is assumed, while more recent models attempt to describe the disturbance more realistically via more complex mathematical formulations. Although these new models describe the real in situ behaviour more realistically than the early ones, they may not always be suitable for practical use as many of the required variables are difficult to assess by standard investigation methods. This study investigates and discusses the difference between some of the available models and evaluates the influences on the results of the variables incorporated in the models.

  • 78.
    Müller, Rasmus
    et al.
    Tyréns AB.
    Larsson, Stefan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Hydraulic Conductivity and Coefficient of Consolidation of Two Sulphide Clays in Sweden2012In: Geotechnical and Geological Engineering, ISSN 0960-3182, E-ISSN 1573-1529, Vol. 30, no 1, p. 173-186Article in journal (Refereed)
    Abstract [en]

    The variation and anisotropy in hydraulic conductivity and the coefficient of consolidation was investigated for two Swedish sulphide clays. A series of constant rate of strain oedometer tests was performed on samples trimmed in the vertical and horizontal direction. A methodology to evaluate the horizontal coefficients of consolidation c h via the horizontal hydraulic conductivity k h and the vertical compression modulus M v is proposed. Laboratory evaluations of c h are also compared with determinations of c h from in situ piezometer measurements in vertically drained sulphide clay. Furthermore, the validity of the empirical correlation between hydraulic conductivity change index C k and initial void ratio e 0, C k = 0.5e 0 (Tavenas et al. in Can Geotech J 20(4):645-660, 1983b), was investigated for the sulphide clays. The results from the investigation show large ranges in measured hydraulic conductivities and coefficients of consolidation. However, the results indicate that the correlation C k = 0.5e 0 is valid. The anisotropy in hydraulic conductivity and the coefficient of consolidation of the sulphide clays tested seems to be small. For design purposes, multiple tests for assessment of hydraulic conductivity and the coefficient of consolidation should be made, and a partial factor of safety, depending on the requisite level of safety and the spatial variability of the parameters, should be introduced. For design purposes in this type of clay, k h = k v and c h = c v are suggested.

  • 79.
    Müller, Rasmus
    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.
    Multivariat analys: hur mycket ska jag undersöka för att vara säker?2013In: Bygg & teknik, ISSN 0281-658X, no 1, p. 71-74Article in journal (Other (popular science, discussion, etc.))
    Abstract [sv]

    I samband med Statens Järnvägars Geotekniska Kommissions slutbetänkande, SJ (1922), där man för första gången nämner termen ”geoteknik”, fastslogs att det inte är möjligt att exakt fastställa förutsättningarna för kraftjämnvikt för svag undergrund och att man måste validera ställda förutsättningar med uppmätning av faktiska förhållanden i fält. Idag är det naturligt för alla geotekniker och bergmekaniker att utföra sonderingar, borrningar, provtagningar och laboratorieförsök på den aktuella jorden eller bergmassan för att uppskatta dess egenskaper.

  • 80.
    Müller, Rasmus
    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.
    Berg, Kjell-Ola
    Stabilitet för en järnvägsbank byggd på sulfidlera2010In: Bygg & teknik, ISSN 0281-658X, no 1, p. 31-41Article in journal (Other (popular science, discussion, etc.))
  • 81.
    Müller, Rasmus
    et al.
    Tyréns AB.
    Larsson, Stefan
    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.
    Extended multivariate approach for uncertainty reduction in the assessment of undrained shear strength in clays2014In: Canadian geotechnical journal (Print), ISSN 0008-3674, E-ISSN 1208-6010, Vol. 51, no 3, p. 231-245Article in journal (Refereed)
    Abstract [en]

    Important features of the multivariate approach are discussed, and an extension to this approach is proposed whereby the total uncertainty in site investigation methods due to spatial averaging is assessed prior to its adoption. Results from a site investigation of spatially averaged values of undrained shear strength (S-u) and the corresponding coefficient of variation (COVSu) in Veda sulphide clay were used as a practical illustration of the extended multivariate approach and provide a basis for discussion. The inherent variability and scales of fluctuation for different methods are presented. The study shows the usefulness of the extended multivariate approach for the evaluation of representative values of S-u and COVSu based on results from different methods. It is also a way of implicitly reducing the transformation errors that arise when a property is derived from measurement results. Nevertheless, considerable care must be taken as a much lower COV for one method will have a significant impact on the results.

  • 82.
    Müller, Rasmus
    et al.
    Tyréns AB.
    Larsson, Stefan
    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.
    Multivariate stability assessment during staged construction2016In: Canadian geotechnical journal (Print), ISSN 0008-3674, E-ISSN 1208-6010, Vol. 53, no 4, p. 603-618Article in journal (Refereed)
    Abstract [en]

    For staging the construction of embankments on soft clay, an important aspect in deterministic or probabilistic stability analyses is the assessment of the representative average values and associated uncertainties for the undrained shear strength as the height of the embankment is sequentially increased. Assessments made prior to construction can be verified by performing observations during the construction phase. All relevant available information should be incorporated into an analysis to increase the level of confidence and the objectivity of the assessment. To this end, we apply an extended multivariate approach to assess the undrained shear strength using different indirect measurement methods during the staged construction of the Veda embankment (Sweden). This multivariate approach implies that uncertainties associated with the assessments are reduced, and objectively weighted averages are obtained. The resulting implications on the calculated deterministic safety factors and the probabilistically retrieved reliability indices of the embankment are thoroughly discussed in this work.

  • 83.
    Müller, Rasmus
    et al.
    Tyréns AB.
    Larsson, Stefan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Westerberg, Bo
    Luleå Institute of Technology.
    Stability for a high embankment founded on sulphide clay2013In: Proceedings of the Institution of Civil Engeneers: Geotechnical Engineering, ISSN 1353-2618, E-ISSN 1751-8563, Vol. 166, no 1, p. 31-48Article in journal (Refereed)
    Abstract [en]

    During staged construction of embankments on clay foundations, the undrained shear strength s(u) increases due to consolidation during the construction process. The increase is usually related to the pre-consolidation pressure sigma'(p) by way of the ratio s(u)/sigma'(p) and is important when assessing the stability of an embankment. Properties controlling the increase are usually associated with various unknowns that can be difficult to predict before construction. A case involving a large embankment built on vertically drained sulfide clay is presented. Empirical knowledge and experience of similar constructions on sulfide clay were limited, therefore there were uncertainties of the soil-drain interaction and how the soil would behave under the embankment load. A trial embankment was built to gather knowledge and experience of this particular soil and the observational method was adopted. The study presents how embankment stability was predicted at design stage and controlled during construction. It highlights the importance and usefulness of obtaining measurement data from different types of measurements. Laboratory tests and a large number of in situ tests at different stages during construction were performed to assess s(u)/sigma'(p) ratios in the sulfide clay. The mean s(u)/sigma'(p) ratio was estimated by means of statistical analysis to 0.25 for a large stress interval.

  • 84.
    Nejad Ghafar, Ali
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Ali Akbar, Saman
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Al-Naddaf, Manar
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Draganovic, Almir
    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.
    Uncertainties in Grout Penetrability Measurements; Evaluation and Comparison of Filter pump, Penetrability meter and Short slot2017In: Geotechnical and Geological Engineering, ISSN 0960-3182, E-ISSN 1573-1529Article in journal (Refereed)
    Abstract [en]

    To measure grout penetrability in fractured hard rock, various measuring instruments have been developed over the years. Penetrability meter and Filter pump have been designed to use in both the lab and the field. Short slot has been applicable mainly in the lab due to its complexity. The fact, that these instruments have been built based on different assumptions, limitations, and test conditions, makes their results occasionally in contradict. Deficiency in design of the instruments as well as the methods of evaluating grout penetrability is additionally a basis for uncertainty in results. This study is an experimental effort to determine and thoroughly perceive the nature of the most governing uncertainties in grout penetrability measurements. The test apparatus, procedure, and method used to evaluate the grout penetrability in both Penetrability meter and Filter pump were thus modified. The aim was to control the corresponding uncertainties and make their limitations and test conditions as similar as possible with the ones in Short slot. The results suggested that to obtain a more realistic evaluation of the grout penetrability, measurement should be accomplished at both the high and the low pressures with sufficient grout volume using Short slot. Moreover, application of both Filter pump and Penetrability meter is no longer recommended due to the revealed uncertainties.

  • 85.
    Nejad Ghafar, Ali
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Draganovic, Almir
    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.
    AN EXPERIMENTAL STUDY OF THE INFLUENCE OF DYNAMIC PRESSURE ON IMPROVING GROUT PENETRABILITY2015Report (Other academic)
    Abstract [en]

    In order to increase the sealing efficiency in rock grouting, the fractures should be entirely grouted while the filtration of cement particles is an obstacle. By reducing the filtration, penetrability of grout will be increased resulting in a more reliable grouting. Some of the advantages of controlling filtration are decreas in time, costs and the environmental impacts of the projects. Increase in the safety margins of the projects during both the construction and the operation are also among the benefits of regulating the filtration.

    Use of variable pressure for improving grout penetrability has been studied in both the lab and the field over the years. The focus of the previous investigations was mainly on application of high frequency oscillating pressure using artificial parallel plates without constrictions with openning sizes larger than 100 μm. The mechanism of improvement of grout penetrability was interpreted as reduction in viscosity due to the oscillation in all those studies. The missing parts of the resulted knowledge are the influences of different shapes of the variable pressure and the effects of low frequencies i.e. longer cycle periods to penetrate through micro fractures smaller than 100 μm with constrictions. Moreover, other mechanisms of improvement of grout penetrability might also be more efficient than reduction in viscosity due to the oscillation.

    The focus of this study is therefore to investigat the influence of low frequency instantaneous variable pressure with different peak and rest periods on regulating the filtration. A pneumatic pressure control system has been thus employed using parallel plates with constrictions of 43 and 30 μm. The proposed mechanism of action was change of flow pattern due to the change in pressure and the corresponding velocity. Comparison of results of the variable and the constant pressures revealed the great impact of the examined variable pressure on improving grout penetrability.

  • 86.
    Nejad Ghafar, Ali
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Mentesidis, Anastasios
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Draganovic, Almir
    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.
    An Experimental Approach to the Development of Dynamic Pressure to Improve Grout Spread2016In: Rock Mechanics and Rock Engineering, ISSN 0723-2632, E-ISSN 1434-453X, Vol. 49, no 9, p. 3709-3721Article in journal (Refereed)
    Abstract [en]

    Dynamic grouting is one of the methods to improve grout spread in rock that have been investigated since 1985. The results were promising, but all tests were performed under noticeable simplifications related to conditions in rock fractures. This study is an experimental approach to improve the grout spread using low-frequency instantaneous variable pressure as a new alternative with better control of filtration. The method is tested through parallel plates with constrictions of 30 and 43 µm under the applied pressures with 4 s/8 s and 2 s/2 s peak/rest periods. The results reveal conclusively the effectiveness of the method and provide a basis for further development of dynamic grouting.

  • 87.
    Nejad Ghafar, Ali
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Mentesidis, Anastasios
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Draganovic, Almir
    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.
    Ett nytt sätt att förbättra inträngnigs egenskaperna hos cementbaserat injekteringsbruk med momentant varierande tryck2016In: Bygg & teknik, ISSN 0281-658X, no 1, p. 17-22Article in journal (Other (popular science, discussion, etc.))
    Abstract [sv]

    Ett mycket viktig moment i samband med undermarksbyggande är tätning av konstruktioner för att hindra vatteninflöde eller ett eventuellt läckage av lagrade material i konstruktionen. Sedan mitten på 1980-talet har man på Kungliga tekniska högskolan (KTH) forskat kring injekteringen av sprickor i berg med varierande tryck för att förbättra inträngningsförmågan av cementbaserade bruk. I tidigare studier har man huvudsakligen undersökt effekten av högfrekventa oscillerande tryck på brukets inträngningsförmåga men den uppnådda förbättringen har visat sig vara relativt begränsad. I ett doktorandprojekt på KTH har vi genomfört en experimentell studie för att undersöka påverkan av istället ett lågfrekvent tryck med en momentan tryckförändering på brukets inträngningsförmåga. Resultaten har visat på en betydande förbättring av inträngningsförmågan hos bruket jämfört med injektering med konstant tryck. Projektet har finansierats av Stiftelsen Bergteknisk Forskning (BeFo), Svenska Byggbranschens Utvecklingsfond (SBUF) och Trafikverket.

  • 88.
    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.
    Pronina, Elizaveta
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Draganovic, Almir
    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.
    Evaluation of the Real Time Grouting Control (RTGC) Theory using an Artificial Fracture with Variable Aperture2018Manuscript (preprint) (Other academic)
    Abstract [en]

    The real time grouting control (RTGC) theory has been developed to monitor the spread of grout in rock fractures. It predicts the extent of the grout spread over time using the grout properties and the applied pressure. Despite extensive work conducted to verify it in both the lab and the field, it has not yet been sufficiently investigated in the lab under geometry conditions similar to a real fracture in rock. This paper presents a novel effort to examine the performance of the RTGC theory in the presence of constrictions by using an artificial fracture, the so-called varying aperture long slot (VALS). The paper compares the predictions of grout propagation with the experimental results. The predictions obtained using a hydraulic aperture, the way that the theory was previously used in the early stages of development, showed relatively good agreement with the experimental results. In predictions obtained using the mean-physical aperture, the way that the theory is currently used in field applications, the results showed considerably faster spread than the experimental results. This suggests that use of the mean-physical aperture does not always give a good approximation of the apertures to employ in predictions using the RTGC theory. Depending on the geometry conditions, the hydraulic aperture might be more realistic.

  • 89. Nilsson, Amelie
    et al.
    Larsson, Stefan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Hållfasthet i kalkcementpelare - nya testrutiner förbättrar kvalitétskontrollen2008In: Väg och vattenbyggaren, ISSN 0042-2177, no 4, p. 48-51Article in journal (Other (popular science, discussion, etc.))
  • 90.
    Palmén, Anders
    et al.
    PEAB Civil Engineering.
    Axelson, Morgan
    Swedish Transport Administration.
    Price, Graham
    Lithic Australia Pty Ltd.
    Larsson, Stefan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Low-temperature calcite precipitation in sand using CIPS2016In: Ground Improvement, ISSN 1365-781X, E-ISSN 1751-7621, Vol. 169, no 1, p. 36-41Article in journal (Refereed)
    Abstract [en]

    The permeation grouting system CIPS (calcite in situ precipitation system) stabilises granular soil by hydrolysing the urea and causing calcite crystals to precipitate at the contact points of the grains. At low temperatures, the activity of urea hydrolysis is slow, causing concern that the CIPS system might not build sufficient strength in order to be an efficient soil stabilisation method. Most of the documented experience and research have been conducted in Australia; in order to examine the suitability of CIPS under Scandinavian climate conditions, where the operating temperature for the method needs to be adjusted to around 10°C, a laboratory study was conducted. The test cores were all treated and stabilised in a temperature-controlled room simulating Scandinavian ground conditions. After different lengths of curing time, some of the cemented samples were tested saturated for unconfined compressive strength (UCS); the other samples were allowed to dry at either 10 or 20°C before they were tested for UCS. The tests showed a rather obvious increase in strength especially after allowing the spent fluid to deplete, causing the samples to dry out; only a slight difference in UCS increase was recorded between the drying temperature of 10 and 20°C.

  • 91. Place, Joachim
    et al.
    Nejad Ghafar, Ali
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Malehmir, Alireza
    Draganovic, Almir
    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.
    On using the thin fluid-layer approach at ultrasonic frequencies for characterising grout propagation in an artificial fracture2016In: International Journal of Rock Mechanics And Mining Sciences, ISSN 1365-1609, E-ISSN 1873-4545, Vol. 89, p. 68-74Article in journal (Refereed)
    Abstract [en]

    We investigate the ultrasonic transport properties of such an idealised fracture whose 100 µm aperture is about 0.02 the wavelength, and filled with various fluids flowing under external forcing. As the artificial fracture is made of two solid and parallel walls separated by a thin fluid layer, we use the thin fluid layer concept to study the compressional (P-) wavefield transmitted across and reflected off the fracture, with no mode-conversion considered. We demonstrate that air and various fluids (water, grouts of varied w/c – water to cement ratio) can be distinguished when injected into the fracture, both at atmospheric pressure or under over-pressure as done in real grouting cases in the field. Then, using an analytical solution, we verify our experimental data and predict the results that can be obtained with a different fracture aperture. Our results illustrate that replicating such ultrasonic measurements both in space and time would allow successfully monitoring the grout propagation within an artificial fracture.

  • 92.
    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.
    Multivariate approach in reliability-based design of a sheet pile wall2016In: Transportation Geotechnics, ISSN 2214-3912, Vol. 7, p. 1-12Article in journal (Refereed)
    Abstract [en]

    In light of a restricted budget, there is a need to stress on the potential savings in conducting qualitative geotechnical investigations. This paper presents a case study on how site investigation efforts can be linked to potential savings in designing a sheet pile wall in central Sweden. The uncertainty in the undrained shear strength is a measure of investigation effort and have been evaluated from multivariate information, several investigation methods. A multivariate analysis (MVA) procedure based on Bayesian statistics was used to cross-validate information obtained by different investigation methods, thus allowing the uncertainty or effort to be updated (reduced) when additional investigations are included in the analysis. The uncertainty was evaluated for two sets of investigations, one of which included additional measurements and hence less uncertainty. A reliability-based design method, FOSM, was then used to study how the additional investigations affected the evaluated uncertainty and one design constraint of the sheet pile wall, namely the depth of penetration. The results show that the depth of penetration can potentially be reduced by approximately 11% of the total wall area.

  • 93.
    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.

  • 94.
    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 .
    Sannolik besparing av spont2016In: Bygg & teknik, ISSN 0281-658X, no 1, p. 47-51Article in journal (Other (popular science, discussion, etc.))
  • 95.
    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.
    Utvärdering av osäkerheter i geotekniska parametrar2014Conference paper (Other academic)
  • 96.
    Prästings, Anders
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Müller, Rasmus
    Larsson, Stefan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    The observational method applied to a high embankment founded on sulphide clay2014In: Engineering Geology, ISSN 0013-7952, E-ISSN 1872-6917, Vol. 181, p. 112-123Article in journal (Refereed)
    Abstract [en]

    Since its introduction, Eurocode 7 has acknowledged the observational method as a valid design approach for geotechnical structures. The observational method is defined in five paragraphs. Although several case studies have concluded that the observational method is useful, the method is still sparsely used. This study compares the actual implementation of the observational method in the Veda embankment project according to the definitions given in Eurocode 7. The outcome of the observational method as a design approach, and the major deviations compared to the definitions in Eurocode 7 are discussed. It is concluded that the design of a multi-staged embankment, where the building process is governed by consolidation in the subsoil, can only partly be adapted to the observational method as defined in Eurocode 7. Furthermore, when this is the case, the possibility of combining "design by calculations" and the observational method is discussed.

  • 97.
    Prästings, Anders
    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.
    Larsson, Stefan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Characteristic values of geotechnical parameters in Eurocode 72019In: Proceedings of the Institution of Civil Engeneers: Geotechnical Engineering, ISSN 1353-2618, E-ISSN 1751-8563, Vol. 172, no 4, p. 301-311Article in journal (Refereed)
    Abstract [en]

    Lack of harmonisation between reliability-based design and the partial factor method in Eurocode 7 (EN 1997-1:2004) is preventing the widespread introduction of a risk-based concept in geotechnical design. This paper discusses how uncertainties are managed according to EN 1997-1:2004 and possible implications of not harmonising the current safety format with reliability-based design. One of several challenges highlighted is how EN 1997-1:2004 defines the characteristic value and design value. The characteristic value is therein defined based on a classical frequentist approach through a confidence interval. From a Bayesian point of view, the current definition does not treat the characteristic value as an uncertain variable. Consequently, the definitions of the characteristic value and design value in EN 1997-1:2004 feature weak connections between uncertainties in the geotechnical properties and the consequences of failure, as regulated by the target reliability index.

  • 98.
    Prästings, Anders
    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.
    Müller, Rasmus
    Tyréns AB.
    Larsson, Stefan
    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.
    Johansson, Fredrik
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Implementing the Extended Multivariate Approach in Design with Partial Factors for a Retaining Wall in Clay2017In: ASCE-ASME Journal of Risk and Uncertainty in Engineering Systems, Part A: Civil Engineering, ISSN 2376-7642, Vol. 3, no 4, article id 04017015Article in journal (Refereed)
    Abstract [en]

    Limitations with the current design using partial factors in Eurocode 7 have been identified. Uncertainties in the material properties are incorporated in both the cautious estimate of the characteristic value and the partial factor. Furthermore, the partial factor is fixed, which limits the opportunities to update the design when additional information is available. A more rational procedure of managing uncertainties in design with partial factors is proposed based on the Bayesian methodology referred to as the extended multivariate approach. The benefits of the approach are illustrated with a case study in which uncertainties of undrained shear strength are characterized for a Swedish clay. The characteristic value and design value is calculated in accordance with the Swedish national annex to Eurocode 7 by adjusting the otherwise fixed partial factor with a conversion factor allowable through EN 1990. The study highlights major benefits in managing uncertainties in a quantifiable and rational way.

  • 99.
    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)
  • 100.
    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.
    On the use of pore pressure measurements in safety reassessments of concrete dams founded on rock2013In: Georisk: Assessment and Management of Risk for Engineered Systems and Geohazards, ISSN 1749-9518, E-ISSN 1749-9526, Vol. 8, no 2, p. 117-128Article in journal (Refereed)
    Abstract [en]

    In probabilistic stability analyses of concrete dams founded on rock, the uplift pressure is often a parameter of major importance. In previous literature, it has been suggested that assessing uplift with pore pressure measurements, instead of using empirical assumptions, could improve the calculated dam safety. This paper presents a coherent methodology to investigate whether incorporating pore pressure measurements has any impact on the calculated dam safety, based on Bayesian linear regression of pore pressure data in combination with series-system and the first-order reliability method. The study concludes that the probability of sliding failure is closely related to the probability of an extreme increase in uplift. Hence, measured uplift should only be incorporated while this probability remains sufficiently small, which requires proper programs both for uplift monitoring and for maintenance of drains and grout curtains.

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