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  • 51.
    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, article id 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.

  • 52.
    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.
    Uotinen, Lauri K.T.
    Department of Civil and Environmental Engineering, Aalto University.
    Rafi, Jalaleddin
    BGC engineering Inc.
    Using observational method to manage safety aspects of remedial grouting of concrete dam foundations2016In: Geotechnical and Geological Engineering, ISSN 0960-3182, E-ISSN 1573-1529, Vol. 34, no 5, p. 1613-1630Article in journal (Refereed)
    Abstract [en]

    As concrete dams age, the need for remedial grouting to reduce the seepage and uplift pressure in the rock foundations under them increases. Based on a case study of a Swedish dam with very low calculated safety against sliding, this paper discusses the application of the observational method (as defined in Eurocode 7) to manage safety aspects during remedial grouting. The studied case was complex in that grouting works posed the risk of causing increased uplift pressure, which could have induced sliding failure along a shallow, persistent, horizontal rock joint in the foundation. The approach applied in the studied case mainly followed the principles of the observational method, except in some highly significant safety aspects for which alternative procedures are suggested and discussed. Implementing these procedures along with the observational method offers a coherent framework to manage the safety aspects of the remedial grouting of concrete dam foundations that is in line with modern risk-informed dam safety policies.

  • 53.
    Yaghoobi Rafi, Jalaleddin
    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.
    Applicability of using GIN method, by considering theoretical approach of grouting design2015In: Geotechnical and Geological Engineering, ISSN 0960-3182, E-ISSN 1573-1529, Vol. 33, no 6, p. 1431-1448Article in journal (Refereed)
    Abstract [en]

    In the practice of grouting of fractured rock, currently, empirical methods are used. Amongst them, the GIN method is popular mostly in Europe and has been tried in many projects. The concept of this method is to limit the combination of pressure and injected volume to a specific grout intensity number in order to control the energy induced in the rock fractures and to avoid uplift. However, difficulties in employing this method have been reported, which are mainly due to uncertainties in recognizing the distance of grout penetration and the state of the fractures during grouting and at the completion grouting. In this paper, the purpose has been examining the applicability of the GIN method by defining the characteristic curve of the P·V diagram (referred to here as the hyperbola) and suggesting appropriate completion criteria based on the radius of grout spread around the borehole. This will provide the chance to assign a permitted level of fracture deformation (or jacking) to the GIN by considering the formulation of fracture deformation based on grout propagation in a previously developed theoretical approach by Stille et al. (Geotech Geol Eng 30:603–624, 2012) as a part of the Real Time Grouting Control Method. Thus, in attaining the hyperbola, the identified radius of grout spread is achieved and the resulting fracture deformation at this completion point can be beneficial in improving penetrability. However, if the full extent of this deformation extends beyond the grouted zone, part of the fracture may remain un-grouted, and this will affect the sealing efficiency of the grouting program. This may be continued by selecting a smaller GIN and reducing the grouting pressure as the real time pressure–volume plot moves along the hyperbola, which will bring the fracture back to its initial state as grouting approaches the completion point, i.e. when the grout has spread to the desired distance. This hypothesis has been examined against the grouting works performed in three different real projects, for which the grouting parameters can be determined from the available grouting records. It is concluded that the GIN used in practice was much higher than the theoretically estimated values obtained through the proposed analytical solution. Furthermore, in the grouting of fractures close to the surface, the radius of grout spread impacts the GIN significantly, and only a limited grouting pressure is applicable, thus in using split spacing technique in such circumstances, different GINs should be selected for different sets of boreholes to obtain enough propagation at the maximum applicable pressure. The introduced analytical solution introduced in this paper can be a useful procedure for designing the GIN based on the grout spread. Nevertheless, it becomes complicated in dealing with fracture deformation. In a difficult grouting case where the demand for sealing is high, the recommendation is to use the proposed theoretical approach, which provides detailed information during the actual grouting procedure, by estimation of the radius of grout spread and the state of the fracture in real time

  • 54.
    Deckner, Fanny
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics. NCC Construction, Sweden.
    Viking, Kenneth
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics. NCC Construction, Sweden.
    Hintze, Staffan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics. NCC Construction, Sweden.
    Aspects of Ground Vibrations due to Pile and Sheet Pile Driving2015In: The Electronic journal of geotechnical engineering, ISSN 1089-3032, E-ISSN 1089-3032, Vol. 20, no 19, p. 11161-11176Article in journal (Refereed)
    Abstract [en]

    Vibrations due to pile and sheet pile driving are part of a complex process involving several factors that influence both vibration magnitude and frequency. Better understanding and prediction of the vibrations generated will greatly benefit the civil engineering practice as well as the construction industry. An important component in understanding vibrations due to pile driving is to comprehend and understand working procedures and the influence of different factors. The objective is to present and discuss factors and working procedures that influence vibrations caused by pile driving, based on three current field tests and formerly presented experience from literature. It is concluded that the factors have the highest impact on ground vibrations due to pile driving are the geotechnical conditions, the vibration generated at the source, the distance from the source and the installation method.

  • 55.
    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.

  • 56.
    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, p. 13439-13460Article 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.

  • 57.
    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, article id 07014008Article in journal (Refereed)
  • 58.
    Westerberg, Bo
    et al.
    Swedish Geotechnical Institute, Linköping, Sweden.
    Müller, Rasmus
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics. Tyréns AB, Sweden.
    Larsson, Stefan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Evaluation of undrained shear strength of Swedish fine-grainedsulphide soils2015In: Engineering Geology, ISSN 0013-7952, E-ISSN 1872-6917, Vol. 188, p. 77-87Article in journal (Refereed)
    Abstract [en]

    In Swedish practice, there is a long tradition of evaluating undrained shear strength from fall-cone tests and field vane tests. During the last 20 years cone penetration tests have also become widely used. However, the results from all these test methods have to be evaluated using empirical factors. The factors generally used for Swedish clays are related to liquid limit and overconsolidation, but they are not applicable to all types of fine-grained soils and can often be improved by local calibration for the particular type of soil in the area of current interest. For this calibration, the results of direct simple shear tests and/or triaxial tests in the laboratory are normally used. This paper presents an evaluation for Swedish fine-grained sulphide soils, for which a general correction factor of 0.65 for field vane tests and fall-cone tests, a cone factor Nkt of 20.2 for cone penetration tests and a relation cu,DSS/(σ′cOCR−0.2) of 0.28 have been found. No correlations were found between these empirical factors and the clay content, liquid limit or organic content, but a relationship was found between the overconsolidation ratio and both the cone penetration test and the field vane test. The sulphide soils in question are found in northern Sweden along the coast of the Gulf of Bothnia. They aremostly classified as organic silt or organic clay,which is normally silty.

  • 59.
    Wersäll, Carl
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Larsson, Stefan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Rydén, Nils
    Lund Universitet.
    Nordfelt, Ingmar
    Dynapac.
    Frequency Variable Surface Compaction of Sand Using Rotating Mass Oscillators2015In: ASTM geotechnical testing journal, ISSN 0149-6115, E-ISSN 1945-7545, Vol. 38, no 2, p. 198-207Article in journal (Refereed)
    Abstract [en]

    The influence of vibration frequency was studied in 110 small-scale compaction tests conducted using a vertically oscillating plate. The underlying soil was dry sand, or sand close to the optimum water content. The results showed that there is a resonant amplification, providing a slightly higher degree of compaction. Frequency has a major influence on soil compaction. An iterative method for calculating the dynamic response of the plate, incorporating strain-dependent properties of the soil, is also presented. The calculated frequency response agrees fairly well with measured quantities.

  • 60.
    Rahman, Mashuqur
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Håkansson, Ulf
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics. Skanska AB, Sweden.
    Wiklund, Johan
    SIK – The Swedish Institute for Food and Biotechnology.
    In-line rheological measurements of cement grouts: Effects of water/cement ratio and hydration2015In: Tunnelling and Underground Space Technology, ISSN 0886-7798, E-ISSN 1878-4364, Vol. 45, p. 34-42Article in journal (Refereed)
    Abstract [en]

    The rheological properties of cement based grouts change with water/cement ratio and time, during the course of hydration. For this reason, it is desirable to be able to measure this change continuously, in-line, with a robust instrument during the entire grouting operation in the field.The rheological properties of commonly used cement grouts were determined using the Ultrasound Velocity Profiling combined with the Pressure Difference (UVP. +. PD) method. A non-model approach was used that directly provides the properties, and the results were compared with the properties obtained using the Bingham and Herschel-Bulkley rheological models. The results show that it is possible to determine the rheological properties, as well as variations with concentration and time, with this method.The UVP. +. PD method has been found to be an effective measuring device for velocity profile visualization, volumetric flow determination and the characteristics of the grout pump used.

  • 61.
    Deckner, Fanny
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics. NCC Construction Sverige AB, Stockholm, Sweden.
    Viking, Kenneth
    Guillemet, Claire
    Hintze, Staffan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics. NCC Construction Sverige AB, Stockholm, Sweden.
    Instrumentation System for Ground Vibration Analysis During Sheet Pile Driving2015In: ASTM geotechnical testing journal, ISSN 0149-6115, E-ISSN 1945-7545, Vol. 38, no 6, article id UNSP GTJ20140275Article in journal (Refereed)
    Abstract [en]

    To enable the study of the sheet pile-soil interaction during driving, it was essential to have a record of the sheet pile vibrations as well as the vibrations at depth in the surrounding soil. In this paper, an instrumentation system for vibration analysis during vibratory sheet pile driving was presented. The instrumentation system was used in a full-scale field test where vibrations were measured on the sheet pile as well as at depth in the ground. The new instrumentation system and the field test were thoroughly described. As a sheet pile was driven into the ground, vibrations were transferred both at the toe and along the shaft. Whether it was the toe or the shaft that created the largest contribution to vibrations in the ground is debated in literature. Results from the field test were presented in order to investigate the effect of the position of the sheet pile toe on the ground vibrations at depth. It was shown that, within a distance of about 1.6m from the driven sheet pile, the ground vibrations at depth were affected by the passing of the sheet pile toe. The current field test also indicated that the toe contributed to more ground vibrations than the shaft.

  • 62.
    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, p. 165-178Article 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.

  • 63.
    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.

  • 64.
    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, p. 16-30Article 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.

  • 65.
    Johansson, Fredrik
    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.
    A conceptual model for the peak shear strength of fresh and unweathered rock joints2014In: International Journal of Rock Mechanics And Mining Sciences, ISSN 1365-1609, E-ISSN 1873-4545, Vol. 69, p. 31-38Article in journal (Refereed)
    Abstract [en]

    Several criteria have been proposed over the years in order to predict the peak shear strength of rock joints.The most widely used criterion is the JRC-JCS criterion by Barton. It says that changes in the peak shear strength originate from surface roughness, joint wall compressive strength and normal stress. A limitation with this criterion is that the contribution from roughness could be overestimated for natural and mismatched joints if the joint roughness coefficient, JRC, is estimated based on the direct profiling method. To account for this effect, Zhao introduced the joint matching coefficient, JMC, which accounts for the matedness of the joint. In addition to this, it is known that the scale of the sheared joint could affect the peak shear strength. However, no criterion exists that describes how roughness, matedness and scale interact. In this paper, a conceptual model is proposed. The model is based on adhesion and fractal theory, measurements of surface roughness and the anticipated variation of the number and size of the contact points. The model proposes how the compressive strength and the roughness of the joint surface together with the matedness of the joint interact in order to form the shear strength of the joint under constant normal load conditions. The model also suggests an explanation for the scale effect of rock joints with respect to the surface roughness.

  • 66.
    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, p. 249-259Article 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.

  • 67.
    Yaghoobi Rafi, Jalaleddin
    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.
    Control of rock jacking considering spread of grout and grouting pressure2014In: Tunnelling and Underground Space Technology, ISSN 0886-7798, E-ISSN 1878-4364, Vol. 40, p. 1-15Article in journal (Refereed)
    Abstract [en]

    This paper describes a theoretical approach for monitoring fracture dilatancy (or “jacking”) during grouting. From this, a methodology to optimize the grout pumping pressure has been developed, based on the required penetration length (i.e. the distance that the grout spreads from the grout hole into the network of fractures within the rock mass). Empirical rules are put forward to prevent the damage that may result from uncontrolled deformation (Jacking) of the fractures, by limiting either pumping pressure or the injected grout volume, or by a combination of both. The state of the fractures and the spread of the grout when these limits are reached are discussed. The theoretical approach, which is referred to here as the Real Time Grouting Control Method, enables the estimation of grout penetration length or “spread” in real time. This gives an opportunity to monitor fracture dilation as it happens and, for the purpose of this paper, the allowable limits of elastic deformation and jacking have been estimated based on the grout spread. Two case histories are analyzed, for which the physical reaction of the fracture deformation with time and grout spread are determined from the recorded pressure and flow. By comparing the observed physical reaction with the theories for jacking presented here, the Real Time Grouting Control Method has been validated, and it is shown that this theoretical approach is superior to commonly used empirical methods, in that it allows the optimization of the pumping pressure to achieve a given penetration length in the shortest time and with an acceptable fracture dilatancy. This approach is a major step forward in customizing grouting works.

  • 68.
    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.

  • 69.
    Draganović, Almir
    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.
    Filtration of cement-based grouts measured using a long slot2014In: Tunnelling and Underground Space Technology, ISSN 0886-7798, E-ISSN 1878-4364, Vol. 43, p. 101-112Article in journal (Refereed)
    Abstract [en]

    Penetrability of cement-based grout is an important issue when sealing the rock around tunnels and measurement of this property of the grout is needed for designing the grouting process and the development of grout. This paper investigates plug-building or the filtration process in a long slot where a slot constriction is placed relatively far from both the "borehole" and the end of the slot. In this slot, a certain shear stress develops before and after a constriction, which may influence plug-building at the constriction. This method is also compared with short slot and penetrability meter. The smallest groutable fracture for all three measured grouts is reasonably close to 75 mu m. Measurements using the long slot showed better penetrability results compared to the short slot and the penetrability meter. The short slot is more practical and gives reasonably good results. The penetrability meter underestimates the penetrability of the grouts.

  • 70.
    Spross, Johan
    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.
    On the observational method for groundwater control in the Northern Link tunnel project, Stockholm, Sweden2014In: Bulletin of Engineering Geology and the Environment, ISSN 1435-9529, E-ISSN 1435-9537, Vol. 73, no 2, p. 401-408Article in journal (Refereed)
    Abstract [en]

    For tunnelling in rock in Sweden, the public authorities usually set stringent requirements on low groundwater inflow to the tunnel, to minimise the risk of building settlement and the environmental impact. To improve this groundwater control, the potential application of the observational method in this matter was studied. A comparison was made between the actual implementation of groundwater control in the Northern Link road tunnel project in Stockholm and the definition of the observational method in Eurocode 7. The results showed that the groundwater control in the Northern Link project mainly agreed with the Eurocode. The significance of the deviations was discussed, and it was concluded that adopting the observational method for groundwater control so that it complied with Eurocode 7 would mostly entail simply a formalisation of today's procedures.

  • 71.
    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.

  • 72.
    Bagheri, Mehdi
    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.
    A new analytical solution based on joint relaxation for analyzing symmetrical block stability2013In: International Journal for Numerical and analytical in geomechanics,, ISSN 0363-9061, Vol. 37, no 8, p. 771-786Article in journal (Refereed)
    Abstract [en]

    The magnitude of clamping forces has a significant influence on the estimated ultimate pullout force of a block. The Crawford–Bray equation, which is fundamental in considering clamping forces, is only a function of horizontal stress and block height. Further research to incorporate the influence of induced stress in block stability analysis was considered, but all the previous analytical solutions for analyzing block stability assume a continuum medium to estimate clamping forces and do not allow joint deformations to occur before block movement due to gravity. Assuming a continuous medium to estimate clamping forces leads to an overestimation of block stability and therefore unsafe design. In this paper, an attempt has been made to deepen the understanding of the block failure mechanism and correct the estimated magnitude of clamping forces in a discontinuous medium. A conceptual model is proposed based on the loading–unloading of the block from an in-situ state to failure. Based on this model, an analytical solution has been developed that calculates clamping forces in a discontinuous medium. The validity and model uncertainty of the solution were checked for different conditions. The new analytical solution is both precise and accurate and can be used as a design tool to estimate block stability.

  • 73.
    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, p. 619-632Article 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.

  • 74.
    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.

  • 75.
    Wersäll, Carl
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Larsson, Stefan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Small-Scale Testing of Frequency-Dependent Compaction of Sand Using a Vertically Vibrating Plate2013In: ASTM geotechnical testing journal, ISSN 0149-6115, E-ISSN 1945-7545, Vol. 36, no 3, p. 394-403Article in journal (Refereed)
    Abstract [en]

    Vibratory rollers generally operate at a fixed vibration frequency. It is hypothesized that the compaction of soil could be made more efficient if the frequency could be adapted to specific project conditions. In order to study the applicability to surface compaction, the frequency dependence of compacting dry sand with a vertically vibrating plate was investigated experimentally in 85 small-scale tests. Tests were performed in a test box simulating the free-field condition and with concrete underlying the sand bed. The results show that there is a distinct frequency dependence, implying a significantly improved compaction effect close to the compactor soil resonant frequency. It is suggested that particle velocity is the governing amplitude parameter for vibratory soil compaction, rather than displacement or acceleration. As the soil is compacted, it is also displaced, resulting in surface heave. A larger vibration amplitude implies greater displacement relative to the compacted volume. It was also observed that the compaction and strain-dependent reduction of soil stiffness are closely related.

  • 76.
    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.

  • 77. Wilde, Marie Westberg
    et al.
    Johansson, Fredrik
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    System Reliability of Concrete Dams with Respect to Foundation Stability: Application to a Spillway2013In: Journal of Geotechnical and Geoenvironmental Engineering, ISSN 1090-0241, E-ISSN 1943-5606, Vol. 139, no 2, p. 308-319Article in journal (Refereed)
    Abstract [en]

    Structural reliability analysis is not widely used for the design and assessment of concrete dams. In this paper, the system reliability of a spillway structure consisting of two monoliths is calculated. Limit state functions are defined from the failure modes sliding in the concrete rock contact, sliding in the rock mass, and adjusted overturning. Random variables in the limit state functions are defined by stochastic distributions. These are defined based on site investigations and laboratory tests from samples taken at the dam. Simulations and information from the literature are used for the remaining variables. The safety index is calculated by the first-order reliability method for each failure mode and monolith, and the system reliability is approximated by direct integration of the bivariate normal distribution. The output is the safety index including associated sensitivity values at the single failure mode, monolith, and system levels. The results show that the system safety is governed by a persistent rock joint beneath one monolith. A system reliability analysis is found to be a useful tool in the dam risk management process as it can be used to calculate the probability of failure and to identify important failure modes and variables.

  • 78.
    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, p. 21-36Article 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.

  • 79.
    Stille, Håkan
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Gustafson, Gunnar
    Chalmers.
    Hässler, Lars
    Application of new theories and technology for grouting of dams and foundations on rock2012In: Geotechnical and Geological Engineering, ISSN 0960-3182, E-ISSN 1573-1529, Vol. 30, no 3, p. 603-624Article in journal (Refereed)
    Abstract [en]

    Permeation grouting is used to improve rock conditions under dams and foundations. During recent decades, there has been a substantial increase of understanding of the mechanism behind grout spread in fractured rock. It is the penetrability of the grout mix and the spread in the joints which will be the governing factors for the quality of the grout curtain. The flow properties and the pressure will give the required time to achieve the quality. The empirical based refusal and completion criteria of today can be replaced by a more engineering based grouting process. An active control method has been developed in order to govern the grout spread during the grouting operation based on the new theory of spreading of grout. The concept is called the "real time grouting control method". The concept and the latest finding of the mechanism of spreading of the grout in the fractures of the rock mass are presented in the paper. The application of the method on two dam projects is also presented.

  • 80.
    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, p. 231-242Article 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

  • 81.
    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.

  • 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.
    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.

  • 83. Wiklund, J.
    et al.
    Rahman, Mashuqur
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Håkansson, U.
    In-line rheometry of micro cement based grouts - a promising new industrial application of the ultrasound based uvp plus pd method2012In: Applied Rheology, ISSN 1430-6395, E-ISSN 1617-8106, Vol. 22, no 4, p. 42783-Article in journal (Refereed)
    Abstract [en]

    Measurements of the viscosity of non-Newtonian fluids and suspensions having a solid volume fraction of about 30% or more is of major interest from an industrial point of view. Cement paste and cement grouts for injection grouting applications, with water to cement ratios typically in the range of 0.4 and 0.6 - 0.8 by weight, are two examples of industrial fluid systems. Few in-line techniques are available on the market that can be used for these fluid systems and under realistic field conditions. The so-called UVP+PD in-line rheometry method combining the Ultrasound Velocity Profiling (UVP) technique with Pressure Difference (PD) measurements is a promising new tool for industrial applications. This paper presents an initial pre-study that aims to demonstrate the feasibility of the UVP+PD method using cement grouts for process monitoring and control of grouting applications under realistic field conditions. The UVP+PD method was tested and found successful for continuous inline measurements of concentrated micro cement-based grouts with water/cement ratios of 0.6 and 0.8. The test set-up consisted of a combination of an experimental " flow loop" and a conventional field grouting rig - UNIGROUT, from Atlas Copco. The rheological properties were determined, directly in-line and the parameters obtained were subsequently compared with off-line measurements using a conventional rotational rheometer.

  • 84.
    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, p. 15--30Article 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.

  • 85.
    Draganović, Almir
    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.
    Filtration and penetrability of cement-based grout: study performed with a short slot2011In: Tunnelling and Underground Space Technology, ISSN 0886-7798, E-ISSN 1878-4364, Vol. 26, no 4, p. 548-559Article in journal (Refereed)
    Abstract [en]

    Filtration of cement-based grout during penetration through fractures in rock is an important issue while sealing the rock around tunnels. Whether a type of grout could be designed to penetrate a fracture of a certain aperture without filtration is an interesting question that needs to be further investigated. This study examines the question of whether grout penetration can be measured using our designed measuring method as well as which factors and processes influence the penetrability and filtration of the grout.

    The penetration and filtration of grout are complex processes influenced by many factors such as the grain-size curve of the cement, hydration and flocculation, pressure, grain concentration, and the geometry of constriction.

    The measured results were in agreement with the predicted results, indicating that the filtration process in the given geometry describes correctly.

  • 86. Wiklund, Johan
    et al.
    Rahman, Mashuqur
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Håkansson, Ulf
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    In-line rheometry of dense cement suspensions using an Ultrasonic Velocity Profiling with combined Pressure Difference Method (UVP-PD)2011In: Applied Rheology, ISSN 1430-6395, E-ISSN 1617-8106Article in journal (Other academic)
  • 87.
    Bagheri, Mehdi
    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.
    Investigation of model uncertainty for block stability analysis2011In: International journal for numerical and analytical methods in geomechanics (Print), ISSN 0363-9061, E-ISSN 1096-9853, Vol. 35, no 7, p. 824-836Article in journal (Refereed)
    Abstract [en]

    The application of probabilistic design, such as FORM, is expanding rapidly in the design of geotechnical structures. The analytical solution proposed by Crawford and Bray for analyzing block stability can be used as a performance function to carry out probabilistic design. The solution benefits from considering both clamping forces and joint stiffness. However, imperfect assumptions and simplifications in the solution generate model uncertainties. The amount of model uncertainty must be considered in order to assess a reliable design. The purpose of this paper is to identify when the analytical solution is applicable and quantify the model uncertainty of the solution. The amount of model uncertainty for the analytical solution has been assessed for different conditions. The results show that at a shallow depth with a low value of in situ stress ratio (horizontal stress/vertical stress), the analytical solution predicts that the block is stable whereas DEM shows that the block is unstable. The results of the analyses indicate that in cases with low stress ratio, cases with high anisotropy of joint stiffness or the case of a semiapical angle close to the friction angle, the accuracy of the analytical solution is low. Neglecting key parameters, such as the absolute value of joint shear and normal stiffness, vertical in situ stress and its influence on joint relaxation generate model uncertainty in the analytical solution. The analyses show that by having more information about the key parameters, the model uncertainty factor could be identified more precisely.

  • 88.
    Stille, Håkan
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Holmberg, Mats
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Examples of applications of observational method in tunnelling2010In: Geomechanik und Tunnelbau: geomechanics and tunnelling, ISSN 1865-7362, Vol. 3, no 1, p. 77-82Article in journal (Refereed)
  • 89.
    Gothäll, Rikard
    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.
    Fracture-Fracture Interaction during Grouting2010In: Tunnelling and Underground Space Technology, ISSN 0886-7798, E-ISSN 1878-4364, Vol. 25, p. 199-204Article in journal (Refereed)
    Abstract [en]

    Sealing of self-supporting underground constructions is often done with grouting or pre-grouting, most often with cementitious grouts. In order to achieve sufficient sealing, fine fractures must be penetrated long distances before the grout hardens. This is achieved with high injection pressures that rivals the in situ stress normal to the fractures. In this paper, the interaction of parallel fractures during high pressure grouting is modelled and the influence of the resulting dilation is discussed. Both linear and non-linear fracture stiffness is used in the modelling.

  • 90.
    With, Christoffer
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Metrikine, A. V.
    Faculty of Civil Engineering and Geoscience, Delft University of Technology (TUDelft).
    Bodare, Anders
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Identification of effective properties of the railway substructure in the low-frequency range using a heavy oscillating unit on the track2010In: Archive of applied mechanics (1991), ISSN 0939-1533, E-ISSN 1432-0681, Vol. 80, no 9, p. 959-968Article in journal (Refereed)
    Abstract [en]

    As the demand for predictions of train-induced vibrations is increasing, it is essential that adequate parameters of the railway structure are given as input in the predictions. Gathering this information can be quite time-consuming and costly, especially when predictions are required for the low-frequency emission. This article presents a procedure for deriving the effective properties of the foundation under the sleepers of a railway track from measurements taken with a heavy oscillating unit on the track. The unit consists of two masses inside a modified freight car that exert a dynamic force in the range 3-30 Hz on one of the two axles. The ratio of force applied on the axle over the resulting response measured with an accelerometer is studied. The foundation of the sleepers is modelled using a frequency-dependent complex-valued dynamic stiffness.

  • 91.
    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.

  • 92. Hernqvist, Lisa
    et al.
    Fransson, Åsa
    Gustafson, Gunnar
    Emmelin, Ann
    Eriksson, Magnus
    Stille, Håkan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Analyses of the grouting results for a section of the APSE tunnel at Aspo Hard Rock Laboratory2009In: International Journal of Rock Mechanics And Mining Sciences, ISSN 1365-1609, E-ISSN 1873-4545, Vol. 46, no 3, p. 439-449Article in journal (Refereed)
    Abstract [en]

    The grouting results for a tunnel at a depth of 450 min crystalline rock at Aspo HRL were studied. The aims were to investigate whether the methodology used resulted in a successful grouting design and producing a sufficiently dry tunnel, and whether grout penetration and inflow into the finished tunnel corresponded to the predictions. An analysis was made of data from an original cored borehole, drilled before the tunnel was constructed and mapped thoroughly with regard to fractures and transmissivities. The predicted inflow into the tunnel was calculated and found to be four times higher than the measured inflow. The latter was 51/min a long the 70 m tunnel, considered to be a good result at the current depth. New cored control boreholes were drilled along a section of the tunnel. The inflow positions and quantities in these holes, and the positions of grout found in the corresponding cores, were compared with the data from the original borehole. It was found that at the predicted positions of larger fractures, grout was observed and there was no inflow, showing that these had been successfully sealed. At the predicted positions of small fractures, no grout was visible in the cores, and small inflows showed that the grout had not sealed these fractures. The results indicated that cement-based grout successfully sealed fractures down to a hydraulic aperture of about 50 mm but not below 30 mm. This concurs with the initial design aimed at sealing fractures larger than 50 mm.

  • 93.
    With, Christoffer
    et al.
    ÅF-Infrastruktur AB/Ingemansson.
    Bodare, Anders
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Evaluation of track stiffness with a vibrator for prediction of train-induced displacement on railway embankments2009In: Soil Dynamics and Earthquake Engineering, ISSN 0267-7261, E-ISSN 1879-341X, Vol. 29, no 8, p. 1187-1197Article in journal (Refereed)
    Abstract [en]

    A measuring car, the rolling stiffness measuring vehicle (RSMV), has been developed to investigate track conditions. The investigation described in this paper firstly attempts to understand whether the point flexibility of the track, i.e., the track-embankment-subsoil system, can be obtained by simultaneously measuring the force applied to an axle of the measuring car and the resulting acceleration response. Secondly, it attempts to determine the physical properties of the track by modelling it as a Bernoulli-Euler beam oil a Kelvin foundation. The final part of the paper investigates the possibility of predicting displacements on a railway embankment based oil the physical properties obtained after a train passage. Results from two sites in Sweden, Kumla and Kåhög, have been used. Investigations give encouraging results. However, as seen here, it can be difficult to analyse and obtain parameters if the resonance frequency of the system is low. The peak particle displacement of the ballast on the railway embankment was achieved with fair accuracy for both Kumla and Kåhög using the results from the accelerometer on the RSMV.

  • 94.
    Stille, Björn
    et al.
    Chalmers.
    Stille, Håkan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Gustafson, Gunnar
    Chalmers.
    Kobayashi, Shinji
    Experience with the real time grouting control method2009In: Geomechanik und Tunnelbau: geomechanics and tunnelling, ISSN 1865-7362, Vol. 2, no 5, p. 447-459Article in journal (Refereed)
    Abstract [en]

    A new concept of "real time grouting control method" is described by which grout penetration and grouting control are made applicable in real time by applying theories for grout spread. The stop criterion with this method can be related to achieved grout spread, and grouting may be considered complete when the grout penetration for the smallest fracture to be sealed is above a predetermined target value, or before the grout penetration for the largest fracture aperture reaches a certain maximum limiting value. It might also be possible by online monitoring of the process to predict the course of the grout spread and flow and to analyse the risk of uplift and jacking. Four tunnel projects in Sweden are presented in the paper. These references indicate that the real time grouting control method may be applicable to real grouting design and control.

  • 95.
    Gothäll, Rikard
    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.
    Fracture dilation during grouting2009In: Tunnelling and Underground Space Technology, ISSN 0886-7798, E-ISSN 1878-4364, Vol. 24, p. 126-135Article in journal (Refereed)
    Abstract [en]

    Sealing underground excavations from ingress of water constitutes a large part of both the cost and the risk for many infrastructure projects. In this paper we present a mechanical model for the rock mass response when grouting hard jointed rock. The model predicts a stiff and a non-stiff behaviour and a transition between them that is dependent on the relationship between the grouting pressure and the in situ stress conditions. The predictions are consistent with previously published measurements and explain grouting behaviour that has been difficult to model with previous methods.

  • 96. Andersson, J. Christer
    et al.
    Martin, C. Derek
    Stille, Håkan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    The Aspo Pillar Stability Experiment: Part II-Rock mass response to coupled excavation-induced and thermal-induced stresses2009In: International Journal of Rock Mechanics And Mining Sciences, ISSN 1365-1609, E-ISSN 1873-4545, Vol. 46, no 5, p. 879-895Article in journal (Refereed)
    Abstract [en]

    A 1-m-thick pillar was subject to coupled excavation- and thermal-induced stresses to induce brittle rock mass yielding. The yielding strength of the heterogeneous and fractured rock mass consisting of Aspo diorite was evaluated at eighteen discrete locations using data from the displacement, acoustic emission, and thermal monitoring systems. The average rock mass yielding strength was determined to be 0.59 of the uniaxial compressive strength. The onset of dilation in uniaxial laboratory tests, determined from strain gauge data, was found to occur at approximately 0.45 of the uniaxial compressive strength. It was shown that that the onset of acoustic emission events in situ also occurred when the tangential stress exceeded 0.43 of the uniaxial compressive strength. For sites with absence of in situ data it is recommended that this lower-bound value determined from laboratory data may be used for assessing the in situ rock mass yielding strength. Visual observation and displacement monitoring showed that extent of rock mass yielding is sensitive to small changes in the tangential stress magnitudes. It was determined using three-dimensional modelling that changes in the tangential stress magnitude of approximately 1 MPa was sufficient to cause yielding of the pillar to propagate in what appeared to be intact rock. Observations suggest that without this small stress change yielding of the rock mass would not occur. In other words, there appeared to be a well defined boundary, and if the stresses reached this boundary yielding was observed. However, if stresses were only slightly below this boundary yielding or time-dependant processes were not observed over the monitoring period used in the experiment.

  • 97.
    With, Christoffer
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Bahrekazemi, Mehdi
    Golder Associates AB, S-10460 Stockholm, Sweden .
    Bodare, Anders
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Wave barrier of lime-cement columns against train-induced ground-borne vibrations2009In: Soil Dynamics and Earthquake Engineering, ISSN 0267-7261, E-ISSN 1879-341X, Vol. 29, no 6, p. 1027-1033Article in journal (Refereed)
    Abstract [en]

    This paper presents a comparison between measured train-induced ground vibrations in the free-field before and after countermeasures had been taken at Kahog near Gothenburg in Sweden. A wave barrier of lime-cement columns was constructed parallel to the railway in order to reduce the ground-borne vibrations inside nearby buildings. On top of the barrier an embankment was built to reduce air-borne vibrations. Due to the wave barrier design, part of the energy content of the waves was expected to be reflected by the screen and transmitted energy was expected to be partly scattered. Contribution from the noise-embankment was not thought likely but could not be ruled out due to its fairly large mass and its close proximity to the railway. The effect of the mitigating measures resulted in a 67% reduction of the maximum particle velocity at 30 m and 41% at 60 m from the railway. A simple two-dimensional finite element model has been used to Study the relative importance of the wave barrier and the noise-embankment as contributors to the mitigation recorded of the ground vibrations in the field. It is concluded with respect to ground vibrations that both the barrier and the embankment had a mitigating effect but that the contribution from the barrier dominated. Furthermore, it is seen from the field results as well as the Simulation that the effect of the mitigating action is reduced with increasing distance from the railway.

  • 98.
    Stille, Håkan
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Palmstrom, Arild
    Ground behaviour and rock mass composition in underground excavations2008In: Tunnelling and Underground Space Technology, ISSN 0886-7798, E-ISSN 1878-4364, Vol. 23, no 1, p. 46-64Article in journal (Refereed)
    Abstract [en]

    Underground excavations like tunnels, caverns shafts, are located in a vast variety of rock mass and ground conditions with different modes of behaviour. The paper describes the main parameters and features determining the behaviour of the ground surrounding an underground excavation, namely: (1) the ground conditions (rock mass, stresses and water) and (2) the project related features, (size and shape of the opening and excavation method). Based on this a simple, qualitative division of the rock masses is presented, which together with the influence of stresses, ground water and dimension of the excavation, is used to find the probable behaviour. This may help the user to select appropriate rock engineering tool(s) for the geotechnical design as has been described by the two authors in an earlier paper.

  • 99. Eklund, Daniel
    et al.
    Stille, Håkan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Penetrability due to filtration tendency of cement-based grouts2008In: Tunnelling and Underground Space Technology, ISSN 0886-7798, E-ISSN 1878-4364, Vol. 23, no 4, p. 389-398Article in journal (Refereed)
    Abstract [en]

    Grouting is a widely used method for strengthening and sealing rock, soil and concrete. The possibilities for sealing Structures are of great importance from both an economic and environmental point of view. The cost of grouting has in certain projects been as high as the cost of blasting and excavating the tunnel. To improve the technique for grouting with cement-based material, it is necessary to examine the properties Of the grout mixture used. The ability of a grout to penetrate cavities, channels and porous material (penetrability) depends on two things: rheology and filtration tendency. Extensive laboratory tests on stable, low w/c-ratio grouts show that the most significant limitation to their penetrability is the tendency of cement grains to agglomerate into an impermeable filter cake. In this report, the ability of a grout to prevent passing obstructions in the flow path Without the cement grains clogging and preventing further penetration is called the filtration tendency. An inert material mixture and a cement-based mixture Lire used in these investigations. The inert material does not react with the water added to the mixture. The cement grouts used are based upon three types of commercially available Portland cements and two Portland cements with modified grain-size distribution Curves. Tests performed show that grain-size and grain-size distribution are of great importance to filtration tendency. According to experiments performed with inert and cement material, it seems to be advantageous for penetrability to have a grain-size distribution that does not contain too many fine or coarse grains. It is reasonable to believe that the grain-size distribution should be relatively steep (narrow grain-size range) between minimum and maximum grain-size. The maximum grain-size is of importance in terms of, for example, d(95). Too great maximum grain-size will prevent penetration of the mixture through obstruction of the flow path. According to the tests, the value of d(95) should be 4-10 times less than the aperture to be penetrated by the cement-based mixture. Small amount of small grain-sizes are also important in achieving low filtration tendency of the grout. This is because of the increased tendency for small grains to flocculate into larger agglomerates, compared to larger grain-sizes. The filtration experiments with cement-based grouts show that parameters such as surface chemistry (use of superplasticisers) and cement chemistry (hydration of cement grains) will strongly affect the filtration tendency of the mixture. To visualize the phenomenon of filtration tendency, it can be investigated to a larger-than-usual scale. Filtration experiments to a scale of approximately 100:1 have been performed in order to observe influences of grain concentration and penetrated slot aperture. It can be seen that the grain-sizes used (monodispersed and inert mixture) should be at least 2-3 times smaller than the aperture to be penetrated by the mixture.

  • 100. Nord, Gunnar
    et al.
    Bagheri, Mehdi
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Baghbanan, Alireza
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering (moved 20130630).
    Stille, Håkan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Design consideration of large caverns by using advanced drilling equipment2007In: Felsbau, ISSN 0174-6979, Vol. 25, no 5, p. 131-136Article in journal (Refereed)
123 51 - 100 of 115
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