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  • 1.
    Abbasiverki, Roghayeh
    et al.
    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.
    Larsson, Stefan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Seismic response of buried concrete pipelines subjected to highfrequency earthquakesIn: Geotechnical and Geological Engineering, ISSN 0960-3182, E-ISSN 1573-1529Article in journal (Refereed)
    Abstract [en]

    Buried pipelines are tubular structures that cross large areas with different geological conditions. During an earthquake, imposed loads from soil deformations on concrete pipelines may cause severe damages. In this study, the use of two-dimensional finite element models of pipelines and surrounding soil for simulation of seismic waves that propagate from the bedrock through the soil are demonstrated. The models describe both longitudinal and transverse cross-sections of pipelines and the soil-pipe interaction is modelled as a nonlinear behaviour. The effects of uniform ground with different burial depths, soil layer thickness, soil stiffness and bedrock geometry on the seismic response of reinforced concrete pipelines is studied. Two earthquakes, with high and low frequency contents, are employed for the dynamic analysis. The results show that there is a much smaller risk of damage from high-frequency earthquakes, but that there is a significant effect on the response due to possible irregular ground with inclined bedrock.

  • 2.
    Abbaszadeh Shahri, Abbas
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics. College of Civil Engineering, Roudehen branch, Islamic Azad University, Tehran, Iran.
    Larsson, Stefan
    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.
    CPT-SPT correlations using artificial neural network approach: A Case Study in Sweden2015In: The Electronic journal of geotechnical engineering, ISSN 1089-3032, E-ISSN 1089-3032, Vol. 20, no 28, 13439-13460 p.Article in journal (Refereed)
    Abstract [en]

    The correlation between Standard and Cone Penetration Tests (SPT and CPT) as two of the most used in-situ geotechnical tests is of practical interest in engineering designs. In this paper, new SPT-CPT correlations for southwest of Sweden are proposed and developed using an artificial neural networks (ANNs) approach. The influences of soil type, depth, cone tip resistance, sleeve friction, friction ratio and porewater pressure on obtained correlations has been taken into account in optimized ANN models to represent more comprehensive and accurate correlation functions. Moreover, the effect of particle mean grain size and fine content were investigated and discussed using graph analyses. The validation of ANN based correlations were tested using several statistical criteria and then compared to existing correlations in literature to quantify the uncertainty of the correlations. Using the sensitivity analyses, the most and least effective factors on CPT-SPT predictions were recognized and discussed. The results indicate the ability of ANN as an attractive alternative method regarding to conventional statistical analyses to develop CPT-SPT relations.

  • 3.
    Abbaszadeh Shahri, Abbas
    et al.
    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.
    Johansson, Fredrik
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Updated relations for the uniaxial compressive strength of marlstones based on P-wave velocity and point load index test2016In: INNOVATIVE INFRASTRUCTURE SOLUTIONS, ISSN 2364-4176, Vol. 1, no 1, UNSP 17Article in journal (Refereed)
    Abstract [en]

    Although there are many proposed relations for different rock types to predict the uniaxial compressive strength (UCS) as a function of P-wave velocity (V-P) and point load index (Is), only a few of them are focused on marlstones. However, these studies have limitations in applicability since they are mainly based on local studies. In this paper, an attempt is therefore made to present updated relations for two previous proposed correlations for marlstones in Iran. The modification process is executed through multivariate regression analysis techniques using a provided comprehensive database for marlstones in Iran, including UCS, V-P and Is from publications and validated relevant sources comprising 119 datasets. The accuracy, appropriateness and applicability of the obtained modifications were tested by means of different statistical criteria and graph analyses. The conducted comparison between updated and previous proposed relations highlighted better applicability in the prediction of UCS using the updated correlations introduced in this study. However, the derived updated predictive models are dependent on rock types and test conditions, as they are in this study.

  • 4.
    Al-Naqshabandy, Mohammed
    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.
    Effect of Uncertainties of Improved Soil Shear Strength on the Reliability of Embankments2013In: Journal of Geotechnical and Geoenvironmental Engineering, ISSN 1090-0241, E-ISSN 1943-5606, Vol. 139, no 4, 619-632 p.Article in journal (Refereed)
    Abstract [en]

    The strength variability of soils improved by lime-cement columns is very high, and assessment of the reliability is associated with high uncertainty. Previous research on natural soils has shown that variability has a major impact on the reliability of geotechnical systems. However, concerning ground improvement with lime-cement columns, the effect of the uncertainties associated with improved strength properties on the reliability is unknown. This paper addresses the integration of reliability-based design in the design of embankments founded on soil improved by lime-cement columns by an analysis of a project conducted in Sweden. The uncertainties associated with estimating the strength property based on results from cone penetration tests and their effect on the assessed system reliability are addressed and discussed. The use of variance reduction with respect to the spatial variability of the shear strength of the columns was found to have a major influence on the assessed system reliability. Furthermore, it was found that the transformation uncertainty from measurements based on cone penetration tests has a significant impact on the assessed system reliability. System reliability cannot be improved significantly simply by performing a large number of tests.

  • 5.
    Al-Naqshabandy, Mohammed
    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.
    Partial factor design for a highway embankment founded on lime-cement columns2012Conference paper (Refereed)
    Abstract [en]

    Stability assessment of highway embankments is a common practice in geotechnical engineering. Rational estimation of soil properties is essential for reliable and safe design. However, previous research has shown that high degree of uncertainty is associated with engineering properties and the behavior of the ground improvement with lime-cement columns. Current design methods for stability of lime-cement column are deterministic and the uncertainties are not treated rationally. A reliable design requires rational treatment of uncertainties. This paper addresses the need for application of partial factor design for safety and reliability assessment of lime-cement columns. The study was carried out on an example highway embankment of 6 m height. Resistance and load parameters were considered random variables. The sensitivity factors for the random variables were evaluated from the first order reliability method (FORM). Partial factors were evaluated for the random variables according to the approximate location of the design values. It was shown that the design by partial factor method fulfills both safety and reliability requirements.

  • 6.
    Al-Naqshabandy, Mohammed Salim
    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.
    Larsson, Stefan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Effect of spatial variability of the strength properties in lime-cement columns on embankment stability2012In: Geotechnical Special Publication, ISSN 0895-0563, Vol. 228, 231-242 p.Article in journal (Refereed)
    Abstract [en]

    Spatial variability with respect to the strength in lime-cement columns is an unavoidable source of uncertainty that should be considered in design. Current design method for the assessment of embankment stability, based on the deterministic factor of safety, cannot address the effect of spatial variability. Reliability-based design methodology is a powerful tool that can be used to integrate the variability into the analysis. In this paper, the spatial variability with respect to the undrained shear strength in the soil and in the columns was evaluated based on CPT test. The first order second moment (FOSM) reliability method was applied to address the impact of the spatial variability of the strength in the soil and in the columns on the reliability of an embankment founded on improved soil by lime-cement columns. The paper also presents a technique to evaluate the variance reduction factor over the failure surface. The results propose that the undrained shear strength in the soil and in the columns can be modelled following normal or lognormal distribution. The analysed example show that the reliability increased significantly when the spatial variability was considered

  • 7.
    Al-Naqshabandy, Mohammed Salim
    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.
    Larsson, Stefan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Strength variability in lime-cement columns based on CPT data2012In: Ground Improvement, ISSN 1365-781X, E-ISSN 1751-7621, Vol. 165, no 1, 15--30 p.Article in journal (Refereed)
    Abstract [en]

    Natural and improved soils have relatively high inherent property variability that should be taken into consideration in design. Investigations of the spatial variability in lime-cement columns are important since they provide a rational quantification of the variability parameters needed for a reliability-based design analysis of geotechnical systems. Statistical analyses are used to evaluate the spatial variability parameters, i.e. the mean, the variance, and the scale of fluctuation, which is the distance within which soil properties reveal strong correlation. This paper presents a field test, in which 30 CPT soundings were performed and analyzed statistically in order to address the spatial variability in a group of lime-cement columns, with respect to the cone tip resistance. The objective of this paper is to describe the statistical analyses and to make a contribution to the empirical knowledge about strength variability in a volume of lime-cement columns. Stationarity has been assessed, and the scale of fluctuation has been evaluated in the vertical and horizontal directions. Random field theory was used based on the sample autocorrelation function ACF. The scale of fluctuation was found to be within the range of 0.2-0.7 m and 2-3 m in the vertical and horizontal direction, respectively. A simple design consideration shows that the variance reduction factor has a major influence on the determination of the design value.

  • 8. Axelsson, Morgan
    et al.
    Larsson, Stefan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Column penetration tests for lime-cement columns in deep mixing - experiences in Sweden2003In: Geotechnical Special Publication, ISSN 0895-0563, Vol. 120, 681-694 p.Article in journal (Refereed)
    Abstract [en]

    In this paper column penetration tests for lime-cement columns in deep soil mixing are reviewed. In principle, column penetration tests and reversed column penetration tests are considered. Improved test techniques are presented and discussed based on tests from two test sites in Sweden. The investigations indicate that the reversed column penetration test is the most suitable method for the primary quality test with reference to the uniformity and continuity of the columns. The probe should, however, be installed by the lime-cement column machine short after the manufacturing of the column to avoid disturbances in the mixing process and to enable a random test selection.

  • 9.
    Bergman, Niclas
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Al-Naqshabandy, Mohammed Salim
    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.
    Variability of strength and deformation properties in lime-cement columns evaluated from CPT and KPS measurements2013In: Georisk: Assessment and Management of Risk for Engineered Systems and Geohazards, ISSN 1749-9518, E-ISSN 1749-9526, Vol. 7, no 1, 21-36 p.Article in journal (Refereed)
    Abstract [en]

    The strength variability of soil improved by deep mixing with lime-cement columns is generally high. Eurocode 7 states that selection of characteristic values for geotechnical parameters shall take the variability of measured property values into account. This variability can be considered in the design by using reliability-based design. With reliability-based design, three statistical parameters are needed to evaluate the design value; mean, variance and scale of fluctuation. In this paper, the shear strength of soil improved by lime-cement columns was evaluated using two different penetration methods, the cone penetration test and the column penetration test. The strength was quantified statistically by the mean, variance and scale of fluctuation, while each test method was analyzed and discussed with a focus on its influence on the design value. Based on the analyses, the column penetration test is suggested as a test method for soil improved by lime-cement columns.

  • 10.
    Bergman, Niclas
    et al.
    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. Skanska Sverige AB.
    Larsson, Stefan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Serviceability Limit State design of lime-cement columns - A reliability-based design approach2014In: Geotechnical Safety and Risk IV - Proceedings of the 4th International Symposium on Geotechnical Safety and Risk, ISGSR 2013 / [ed] D . Q . Li, London: Taylor & Francis Group, 2014, 417-422 p.Conference paper (Refereed)
    Abstract [en]

    Deep mixing with lime-cement columns is a ground improvement method used to improve the strength and deformation properties of soft cohesive soils. Due to the complex manufacturing process, the variability in the strength and deformation properties is normally high. A rational approach to include variability in the design process is by introducing Reliability-Based Design (RBD). This paper presents a reliability-based design approach for Serviceability Limit State (SLS) design of soil improved by lime-cement columns using the First-Order Reliability Method (FORM). The paper further presents the impact of uncertainties, reliability indices and area replacement ratios on the relationship between the characteristic value and the design value with respect to the column modulus of elasticity.

  • 11.
    Bergman, Niclas
    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.
    Probabilistic serviceability limit statedesign approach for dry deep mixingManuscript (preprint) (Other academic)
  • 12.
    Bergman, Niclas
    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.
    Alternativ metod för verifiering av hållfasthet hos kalkcementpelare2013In: Bygg & teknik, ISSN 0281-658X, no 1, 75-79 p.Article in journal (Other (popular science, discussion, etc.))
    Abstract [sv]

    Inom ett doktorandprojekt på Kungliga Tekniska högskolan (KTH) har möjligheten till att använda Jb-totalsondering som testmetod för verifiering av hållfasthet hos kalkcementpelare studerats. Syftet med doktorandprojektet, som är finansierat av Svenska Byggbranschens Utvecklingsfond (SBUF) och Trafikverket, är att öka förståelsen för variationer i hållfasthets- och deformationsegenskaper hos kalkcementpelare och att undersöka variationernas betydelse vid sannolikhetsbaserad dimensionering i bruksstadiet, Bergman (2012).

  • 13.
    Bergman, Niclas
    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.
    Comparing column penetration and total–sounding data for lime–cement columns2014In: Ground Improvement, ISSN 1365-781X, E-ISSN 1751-7621, Vol. 167, no 4, 249-259 p.Article in journal (Refereed)
    Abstract [en]

    In Sweden, the method commonly used for the quality control of lime–cement columns is the column penetration test. However, it is recommended for depths of no more than 8 m because the probe easily deviates from the column at greater depths. As an alternative to facilitate keeping the probe vertical, a centre hole is normally bored in the column using the total-sounding test method. The aim of this paper is to quantify the agreement between the two methods. If there is good agreement, it should be possible to use the less expensive and less time-consuming total-sounding test as a complement to the column penetration test. The analyses suggest good agreement between the methods, and it is therefore suggested that the total-sounding test be used as a complement to the column penetration test in evaluating the average strength properties of a group of medium- and high-strength lime–cement columns.

  • 14.
    Bitir (Buliga), Andreea-Cristina
    et al.
    “Gheorghe Asachi” Technical University of Iaşi.
    Muşat, Vasile
    “Gheorghe Asachi” Technical University of Iaşi.
    Larsson, Stefan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Laboratory Methods Used to Assess the Mechanical Properties of Soft Soils Improved by Deep Mixing2015In: Bulletin of the Polytechnic Institute of Jassy, Constructions, Architechture Section, ISSN 1224-3884, E-ISSN 2068-4762, Vol. LXI (LXV), no 4, 165-178 p.Article in journal (Other academic)
    Abstract [en]

    In ground improvement projects by deep mixing, the laboratory experimental programis an important stage by which,the suitable binder and quantity are chosen andgeotechnical performances of improvedsoil are evaluated.In current practice, the design process oflime-cement columns ismainlybased on unconfined compressive strength and the corresponding secant Young's modulusevaluated by unconfined compression tests. In this paper, the main laboratory methods used to assess the mechanical properties of improvedsoil mixed with lime and cement in deep mixing are reviewed. Laboratory preparation of the samples and testing procedures for unconfined compression tests, triaxial tests and oedometer testsare presented. In addition,someexperimental results of tests conducted on soft soils mixed with lime and cement are analyzedand commented.

  • 15.
    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), 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.
    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.
    Challenges in applying fixed partial factors to rock engineering design2017In: Geotechnical Special Publication, ISSN 0895-0563, no 283, 384-393 p.Article in journal (Refereed)
    Abstract [en]

    The Swedish national guidelines for design of the main structural support system in road and railway rock tunnels have been adjusted to cohere with Eurocode 7. In the design guidelines, the limit states that the designer should consider are specified. The main method to account for uncertainties in the Swedish guidelines is similar to the method preferred in Eurocode 7: the partial factor method. For each limit state, fixed partial factors retrieved from different sections of the Eurocodes are specified. However, fixed partial factors may not correspond to the same structural reliability for all design situations. In this paper, we show for a common design situation in rock engineering design how partial factors in theory should vary with design geometries and uncertainties. The derived partial factors are compared to the Eurocodes’ fixed values. We find that using fixed partial factors to ensure structural safety in these limit states might not be suitable. The implications are discussed along with suggestions of other more suitable methods to account for uncertainties in rock engineering design.

  • 16.
    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), 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.
    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.
    Reliability aspects of rock tunnel design with the observational methodManuscript (preprint) (Other academic)
  • 17.
    Daniels, Markus
    et al.
    Bjerking AB.
    Lovén, Katarina
    Skanska Sverige AB.
    Larsson, Stefan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Berg, Joakim
    Skanska Sverige AB.
    Studie visar fördelarna med borrad spont med avseende på markvibrationer2015In: Bygg & teknik, ISSN 0281-658X, no 1, 36-39 p.Article in journal (Other (popular science, discussion, etc.))
    Abstract [sv]

    Då det byggs allt tätare och i känsliga områden blir det allt vanligare att man måste ta hänsyn till markvibrationer. Anläggningsarbeten såsom packning, borrning och pål- och spontinstallationer genererar markvibrationer som kan skada intilliggande bebyggelse, påverka marken negativt samt skapa en otrivsam vistelsemiljö. I känsliga områden är det viktigt att kunna välja rätt metod som skapar acceptabla vibrationsnivåer.

      Det är allmänt vedertaget att vibrationerna som skapas vid installation av borrade stålrör är mindre än vibrationer genererade vid installation av vibrerad spont och slagna pålar. Det har dock inte gått att finna några tillgängliga studier där markvibrationer genererad från borrning respektive vibrerad spont har uppmätts parallellt. Fördelen av att använda borrade stålrör har därför inte kunnat påvisas. Att förutspå vibrationerna analytiskt är mycket komplicerat då det finns ett stort antal parametrar som inverkar på resultatet, både vad det gäller installationsmetoden samt markens beskaffenhet. I Daniels & Lovéns (2014) examensarbete utfört för KTH och Skanska Grundläggning har för första gången en borrad RD-vägg och en vibrerad spont installerats inom samma område med lika markförhållanden samtidigt som vibrationerna uppmätts både i marken och på respektive sponttyp (Figur 1 och 2). Resultaten från undersökningen visar tydligt på skillnaderna i vibrationer och är tänkta att kunna användas vid projektering av spontarbeten där vibrationer blir en faktor att ta hänsyn till.

  • 18.
    Eriksson, Fredrik
    et al.
    Bjerking AB.
    Gemvik, Lina
    Atkins Sverige AB.
    Hov, Sölve
    Atkins Sverige AB.
    Larsson, Stefan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    En bortglömd metod: Elektroosmos,jordförstärkning med hjälp av el2015In: Bygg & teknik, ISSN 0281-658X, no 1, 61-65 p.Article in journal (Other (popular science, discussion, etc.))
    Abstract [sv]

    Elektroosmos är en metod för att dränera och förbättra hållfasthetsegenskaperna hos finkorniga jordar. Metoden har visat sig kunna vara upp till hundra gånger snabbare än mekanisk konsolidering med hjälp av till exempel överlast, Lefebvre & Burnotte (2002). I dagens projekt är både de ekonomiska och miljömässiga aspekterna kanske viktigare än någonsin, och elektroosmos har visat sig kunna vara både miljövänlig och ekonomiskt fördelaktig vilket skulle kunna göra den till en användbar metod i många projekt med geotekniska problem. Som exempel visade Lamont Black & Weltman (2010) i ett projekt med stabilitetsproblem att klimatpåverkan, i form av utsläpp av växthusgaser, minskade med 47 procent vid användande av elektroosmos i jämförelse med till exempel jordspikning. Även kostnaderna minskade med 26 procent jämfört med andra jämförbara metoder. I ett examensarbete, Eriksson & Gemvik (2014), utfört för KTH, Atkins Sverige AB och Sweco Geolab har leror från tre olika platser i Sverige behandlats med elektroosmos. Resultaten visar att elektroosmos effektivt kan dränera en finkornig jord och avsevärt öka dess hållfasthetsparametrar

  • 19.
    Holm, Göran
    et al.
    Statens geotekniska institut.
    Larsson, Stefan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Beyer, Fredrik
    Batman, Mathew
    Genberg, Cristian
    Geokonstruktioner av stabiliserade/solidifierade förorenade muddermassor2009In: Bygg & teknik, ISSN 0281-658X, no 1, 46-51 p.Article in journal (Other (popular science, discussion, etc.))
  • 20.
    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, 573-580 p., 2079Conference paper (Refereed)
  • 21.
    Ignat, Razvan
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Baker, Sadek
    Skanska Sweden AB.
    Larsson, Stefan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Liedberg, Sven
    Skanska Sweden AB.
    Two- and three-dimensional analyses of excavation support with rows of dry deep mixing columns2015In: Computers and geotechnics, ISSN 0266-352X, E-ISSN 1873-7633, Vol. 66, 16-30 p.Article in journal (Refereed)
    Abstract [en]

    In this study, a 2D model of an excavation with a tied back sheet pile wall in interaction with perpendicular rows of deep dry mixed overlapping columns was compared to a 3D model. A method to take into consideration the effect of the overlap zones between columns in a 2D model, where the improved soil was modeled as a composite material, was investigated and the results between the 2D and 3D analyses were compared with focus on predicted failure load, failure mechanism and deformations. The results of this numerical study show that both the area improvement ratio of the improved soil and the quality of the overlap zone has a significant influence on how well a 2D model that incorporates the overlap zone between columns, performs compared to the 3D model.

  • 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 Sverige AB.
    Liedberg, Sven
    Skanska Sverige AB.
    Larsson, Stefan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Behavior of braced excavation supported by panels of deep mixing columns2016In: Canadian geotechnical journal (Print), ISSN 0008-3674, E-ISSN 1208-6010, Vol. 53, no 10, 1671-1687 p.Article in journal (Refereed)
    Abstract [en]

    This paper describes the instrumentation, execution and performance of two full-scale tests where a braced steel sheet pile wall interacting with rows of overlapping dry deep mixing columns was excavated and then loaded to failure. The purpose of these tests was to provide knowledge of the behavior of deep mixing column rows located in passive zone and interacting with a retaining structure. Both tests were extensively instrumented on the active as well as on the passive side of the retaining structure. In both conducted tests a stability failure of the retaining structure occurred, resulting in heave at the bottom of the excavation and large settlements of the ground surface behind the sheet pile wall. For a spacing between LC-panels of 3.0 m a very brittle failure developed suddenly in the clay between the panels with small deformations prior to failure. In the second test, with a spacing of 1.5 m between LC-panels, the failure developed in the LC-panels as well as in the clay between the panels. Even if a similar failure mechanism developed, measured horizontal displacements, horizontal stresses, and pore pressure response prior to failure differed between the tests.

  • 23.
    Ignat, Razvan
    et al.
    Skanska AB.
    Larsson, Stefan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Baker, Sadek
    Skanska AB.
    Studie av 2D/3D numeriskmodellering av kalkcementpelare installerade som överlappande skivor2014In: Bygg & teknik, ISSN 0281-658X, Vol. 1, 80-83 p.Article in journal (Other (popular science, discussion, etc.))
  • 24.
    Kardan, Caesar
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Nik, Leyla
    Geosigma.
    Viking, Kenneth
    NCC Teknik.
    Larsson, Stefan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    CPTu: Kan vi lita på sonderingsresultaten?2015In: Bygg & teknik, ISSN 0281-658X, no 1, 53-58 p.Article in journal (Other (popular science, discussion, etc.))
    Abstract [sv]

    I geotekniska utredningar ingår behovet av att kunna bestämma markförhållanden och jordens egenskaper. Ett antal sonderingsmetoder har utvecklats för detta ändamål och CPTu (Cone Penetration Test med portrycksmätning) betraktas som en av de mer sofistikerade. Denna metod ställer dock höga krav på alla aktörer i processen, det vill säga fältgeotekniker, handläggande geotekniker, geokonstruktörer men även beställaren. Ett vanligt problem med CPTu är osäkerheten i resultaten, osäkerheter kopplat till både utrustning och handhavande. Trots att det idag finns ramverk avseende användning, prestanda, underhåll och andra detaljer, finns det fortfarande en grad av osäkerhet i resultaten. Hur stor denna osäkerhet är och vilka faktorer som inverkar har översiktligt studerats i form av ett examensarbete på KTH Jord- och bergmekanik, under 2014,Kardan (2014), i samarbete med övriga medförfattare. Resultat från studien visar tydligt på skillnader i resultat, en skillnad som är kopplat till både aktörens utrustning och handhavande.

  • 25.
    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, 153-158 p.Conference 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.

  • 26.
    Krounis, Alexandra
    et al.
    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.
    Larsson, Stefan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Shear strength of partially bonded concrete-rock interfaces for application in dam stability analyses2016In: Rock Mechanics and Rock Engineering, ISSN 0723-2632, E-ISSN 1434-453X, Vol. 49, no 7, 2711-2722 p.Article in journal (Refereed)
    Abstract [en]

    The shear strength of the concrete–rock interface has a substantial influence on the sliding stability of concrete gravity dams founded on rock. While several studies have been done on concrete–rock contacts, there remains uncertainty regarding the peak shear strength of partially bonded interfaces. There exists, in particular, an uncertainty regarding the contribution from surface roughness of the unbonded parts to the peak shear strength of the interface due to the dependency of mobilized strength on shear displacement. In this study, a series of 24 direct shear tests are performed under CNL conditions on concrete–rock samples with different bonding conditions. Tests on samples with fully bonded and unbonded interfaces are conducted to study the strain compatibility of the different contacts, while the results of samples with partially bonded interfaces are evaluated in the context of linking the joint roughness of the unbonded parts to the peak shear strength of the interface. The results indicate that a significant part of the surface roughness of the unbonded parts is mobilized prior to degradation of bond strength, in particular for interfaces with low bonding percentages. It is recommended that further research should be conducted to understand how the contribution from roughness change with an increase in scale and degree of matedness.

  • 27.
    Krounis, Alexandra
    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.
    Larsson, Stefan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Influence of cohesive strength in probabilstic sliding stability re-assessment of concrete dams2016In: Journal of Geotechnical and Geoenvironmental Engineering, ISSN 1090-0241, E-ISSN 1943-5606, Vol. 143, no 2, 04016094Article in journal (Refereed)
    Abstract [en]

    For concrete dams, cohesive strength often constitutes a significant share of the overall shear strength of partially bonded concrete-rock interfaces. However, cohesive strength is also associated with great uncertainties that may have a significant impact on the assessed stability of the analyzed structure. In this paper, the merits of including cohesion are evaluated using a probability-based approach to analyze the sliding stability of an existing concrete gravity dam. The shear strength properties of the interface are inferred from a limited number of site-specific tests and previous knowledge from similar structures using Bayesian updating. The study shows that the potential gain from cohesive strength is strongly related to the involved uncertainties and identifies the bonding percentage and basic friction angle as the most influential parameters. The importance of testing, both with regard to the specific project and for future projects, is also highlighted.

  • 28.
    Krounis Guerrero, Alexandra
    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.
    Effects of spatial variation in cohesion over the concrete-rock interface on dam sliding stability2015In: Journal of Rock Mechanics and Geotechnical Engineering, ISSN 1674-7755, Vol. 7, no 6, 659-667 p.Article in journal (Refereed)
    Abstract [en]

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

  • 29.
    Larsson, Stefan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Binder distribution in lime-cement columns2001In: Ground Improvement, ISSN 1365-781X, E-ISSN 1751-7621, Vol. 5, no 3, 111-122 p.Article in journal (Refereed)
    Abstract [en]

    The mixing of soil and binders is a very complex process. The object of the mixing process is to distribute the binder and to achieve a satisfactory mixture for the particular purpose. The requirements on homogeneity may differ for each application. The assessment and definition of mixing quality are difficult and very expensive. This paper discusses the concept of mixing quality with respect to the binder distribution, and the use of mixing indices, as a quantitative assessment. The possibility of using mixing indices with the lime–cement column method is taken up. Statistical analysis was performed on a number of samples taken from four lime–cement columns at Arboga, Sweden. The sampling methodology, the scale of scrutiny and thus the influence of the sample size are discussed. The study shows that mixing indices can be used as a quantitative measure of the mixing quality. The results indicate that the sample size has a considerable influence when the mixing quality is poor and a lesser influence when the mixing quality is relatively good. It is also shown that it is difficult to draw conclusions concerning binder distribution from only a few samples, since the distribution may vary. With more extensive knowledge, it may be possible to assess the mixing quality from only a few samples.

  • 30.
    Larsson, Stefan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Inblandningsprocessen vid kemiskdjupstabilisering - en översikt2000In: Proc. of the 12th Nordic Geotechnical Meeting, 2000, 241-250 p.Conference paper (Other academic)
  • 31.
    Larsson, Stefan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    On the use of CPT for quality assessment of lime-cement columns2005In: Proceedings of the International Conference on Deep Mixing: Best Practice and Recent Advances, 2005, 555-560 p.Conference paper (Refereed)
    Abstract [en]

    This paper presents results from a somewhat unusual application, where CPT was performed inclined in order to investigate the overlapping zone in lime-cement column rows. The column rows had been subjected to large movements due to an embankment failure. The discussion touches upon the evaluation of strength properties, advantages and major drawbacks. The results show that the upper part of the column rows was held together in spite of the fact that the rows had been subjected to large movements. However, the value of using CPT with respect to the assessment of strength properties is strongly questioned due to the small probe size.

  • 32.
    Larsson, Stefan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Recent Developments in Deep Mixing Research in Sweden2013Conference paper (Other academic)
  • 33.
    Larsson, Stefan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Reliabilityanalysis and design issues of ground improvement by deep mixing2012Conference paper (Other academic)
  • 34.
    Larsson, Stefan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Shear box apparatus for modelling chemicalstabilised soil - introductory tests1999In: Dry Mix Methods for Deep Soil Stabilization, Balkema, 1999, 115-121 p.Conference paper (Refereed)
  • 35.
    Larsson, Stefan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    State of Practice Report: Execution, monitoring and quality control2005In: Proceedings of the International Conference on Deep Mixing: Best Practice and Recent Advances, 2005, 732-785 p.Conference paper (Refereed)
    Abstract [en]

    The state of practice of deep mixing concerning execution, monitoring and quality control is highlighted and discussed. Important recently published publications and different deep mixing methods are briefly reviewed. The mixing process in-situ is described and present knowledge concerning influencing factors are reviewed and discussed. The quality control concept of deep mixing is discussed and control methods are reviewed. The extent of testing and the evaluated strength- and deformation properties are discussed. The concept quality and variability in deep mixing are discussed.

  • 36.
    Larsson, Stefan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    The mixing process at the dry jet mixing method1999In: Dry Mix Methods for Deep Soil Stabilization / [ed] H.Bredenberg/G.Holm / B.B.Broms, Balkema, 1999, 339-346 p.Conference paper (Refereed)
  • 37.
    Larsson, Stefan
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Adevik, Sebastian
    Ignat, Razvan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Baker, Sadek
    Skanska Sverige AB.
    A case study on the effect of using surcharge fill as a complement to ground improvement with dry deep mixing2014Conference paper (Refereed)
    Abstract [en]

    Uncertain strength, deformation and flowproperties in dry deep mixing columns often lead to conservative choicesconcerning design values where the design is regularly complemented with asurcharge fill.  The surcharge not onlyleads to increased cost but also to logistical problems where the surcharge isa physical obstacle.  The deformationproperties of a ground improvement were studied by means of two smallembankment load tests.  The settlementmeasurements were also used in FEM analyses, where the effect of surcharge oncreep settlements was investigated.  Basedon the results, the effects of the surcharge were considered negligible and couldsafely be ignored.  The project is anexample how the contractor can use a field test as an effective designapproach.

  • 38.
    Larsson, Stefan
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Ahnberg, Helen
    Ignat, Razvan
    Baker, Sadek
    Discussion of "Numerical Modeling of Geotextile-Reinforced Embankments over Deep Cement Mixed Columns Incorporating Strain-Softening Behavior of Columns" by N. N. S. Yapage, D. S. Liyanapathirana, H. G. Poulos, R. B. Kelly, and C. J. Leo2015In: International Journal of Geomechanics, ISSN 1532-3641, E-ISSN 1943-5622, Vol. 15, no 4, 07014008Article in journal (Refereed)
  • 39.
    Larsson, Stefan
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Al-Naqshabandy, Muhammed
    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.
    Ignat, Razvan
    SVR, C02, Skanska Sverige AB.
    Kalkcementpelare: forskningen på KTH med industrisamverkan2012In: Samhällsbyggaren, ISSN 2000-2408, no 4, 14-18 p.Article in journal (Other (popular science, discussion, etc.))
  • 40.
    Larsson, Stefan
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Axelsson, Morgan
    Rehnman, Sven-Erik
    On the assessment of the mixing quality whenusing the dry jet mixing method2000In: Proceedings of the 4th GIGS, Int. Conf. on Ground Impr. Geosystems, 2000, 99-108 p.Conference paper (Refereed)
  • 41.
    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, 300-311 p.Article 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.

  • 42.
    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, CD-Rom-6p p.Conference 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.

  • 43.
    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)
  • 44.
    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, 67-77 p.Article 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.

  • 45.
    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, 1-15 p.Article 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.

  • 46.
    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, 70-72 p.Article 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.

  • 47.
    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, 573-580 p.Conference 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.

  • 48.
    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, 111-118 p.Conference paper (Refereed)
  • 49.
    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, 25-28 p.Article in journal (Other (popular science, discussion, etc.))
  • 50.
    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, 48-57 p.Article 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.

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