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  • 1301.
    Taeseri, Damoun
    et al.
    ETH Zurich.
    Otsubo, Masahide
    Imperial College London.
    Laue, Jan
    ETH Zurich.
    Towhata, Ikuo
    University of Tokyo.
    New mitigation method for pipelines under the effect of buoyancy forces during seismic events2015Inngår i: Geotechnical engineering for infrastructure and development: proceedings of the XVI European Conference on Soil Mechanics and Geotechnical Engineering / [ed] M.G. Winter, London: Research Publishing Services, 2015, Vol. 4, s. 2213-2218Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Lifeline systems in liquefiable soils are subjected to buoyancy forces during seismic events, causing permanent deformations to pipelines and interrupting their service (e.g. water supply, sewerage, etc.) for extended periods of time. For example, the Great East Earthquake and the Niigata Chuetsu Earthquake (Mimura et al. 2011) caused significant damage through floating of underground lifelines. Different mitigation methods, such as soil compaction, cement mixing or continuous structural measures, are currently used to reduce the liquefaction potential of the fill material. However, these methods are expensive and time consuming when considering the size of the lifelines' networks. This paper studies the "horn-type-structure" as a mitigation method, which is less expensive, more effective and faster to build for existing lifelines. One of the advantages of this method is that the horn-type-structure can be installed in strategic locations across the lifeline network only, thus reducing the overall amount of soil excavation along the entire network. Small scale experiments were conducted at the University of Tokyo and centrifuge tests were conducted at ETH-Zurich, aiming to understand the mechanism better and to develop a calculation method.

  • 1302.
    Tenzer, Robert
    et al.
    The Department of Land Surveying and Geo-Informatics, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong.
    Foroughi, Ismael
    Department of Geodesy and Geomatics, University of New Brunswick, Canada.
    Sjöberg, Lars E.
    Division of Geodesy and Satellite Positioning, Royal Institute of Technology (KTH), Stockholm, Sweden.
    Bagherbandi, Mohammad
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, Samhällsbyggnad, GIS. Division of Geodesy and Satellite Positioning, Royal Institute of Technology (KTH), Stockholm, Sweden.
    Hirt, Christian
    Institute for Astronomical and Physical Geodesy and Institute for Advanced Study, Munich, Germany.
    Pitoňák, Martin
    New Technologies for the Information Society (NTIS), Faculty of Applied Sciences, University of West Bohemia, 301, Czech Republic.
    Definition of Physical Height Systems for Telluric Planets and Moons2018Inngår i: Surveys in geophysics, ISSN 0169-3298, E-ISSN 1573-0956, Vol. 39, nr 3, s. 313-335Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    In planetary sciences, the geodetic (geometric) heights defined with respect to the reference surface (the sphere or the ellipsoid) or with respect to the center of the planet/moon are typically used for mapping topographic surface, compilation of global topographic models, detailed mapping of potential landing sites, and other space science and engineering purposes. Nevertheless, certain applications, such as studies of gravity-driven mass movements, require the physical heights to be defined with respect to the equipotential surface. Taking the analogy with terrestrial height systems, the realization of height systems for telluric planets and moons could be done by means of defining the orthometric and geoidal heights. In this case, however, the definition of the orthometric heights in principle differs. Whereas the terrestrial geoid is described as an equipotential surface that best approximates the mean sea level, such a definition for planets/moons is irrelevant in the absence of (liquid) global oceans. A more natural choice for planets and moons is to adopt the geoidal equipotential surface that closely approximates the geometric reference surface (the sphere or the ellipsoid). In this study, we address these aspects by proposing a more accurate approach for defining the orthometric heights for telluric planets and moons from available topographic and gravity models, while adopting the average crustal density in the absence of reliable crustal density models. In particular, we discuss a proper treatment of topographic masses in the context of gravimetric geoid determination. In numerical studies, we investigate differences between the geodetic and orthometric heights, represented by the geoidal heights, on Mercury, Venus, Mars, and Moon. Our results reveal that these differences are significant. The geoidal heights on Mercury vary from − 132 to 166 m. On Venus, the geoidal heights are between − 51 and 137 m with maxima on this planet at Atla Regio and Beta Regio. The largest geoid undulations between − 747 and 1685 m were found on Mars, with the extreme positive geoidal heights under Olympus Mons in Tharsis region. Large variations in the geoidal geometry are also confirmed on the Moon, with the geoidal heights ranging from − 298 to 461 m. For comparison, the terrestrial geoid undulations are mostly within ± 100 m. We also demonstrate that a commonly used method for computing the geoidal heights that disregards the differences between the gravity field outside and inside topographic masses yields relatively large errors. According to our estimates, these errors are − 0.3/+ 3.4 m for Mercury, 0.0/+ 13.3 m for Venus, − 1.4/+ 125.6 m for Mars, and − 5.6/+ 45.2 m for the Moon.

  • 1303. Tesarik, D.R.
    et al.
    Hustrulid, W.A.
    Nyberg, Ulf
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Assessment and application of a single-charge blast test at the Kiruna mine, Sweden2011Inngår i: Blasting and Fragmentation, ISSN 1937-6359, Vol. 5, nr 1, s. 47-72Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [sv]

    Partikelhastighet (PPV) och avståndsmätningar utförda av svenska forskare presenteras för enskottsladdningar i järnmalm i Kiruna gruvan i norra Sverige. De används tillsammans med teoretiska PPV-värden som beräknats med hjälp av en formel baserad på hydrodynamik för att bestämma skadornas omfattning orsakas av en enda laddning. Denna ekvation, som relaterar PPV till explosiva egenskaper, laddningsgeometri och avstånd från en laddning, tillämpades sedan på en laddning av olika geometri som användes i ortdrivning. En jämförelse mellan beräknade och uppmätta PPV tyder på att strosshålen sannolikt skada läget för hjälparhålen, och att hjälparhålen ger skador där konturhålen sitter. Den praktiska konsekvensen är att typiska skadeberäkningar baserade på mätningar utförda i oskadat berg är konservativa. Detta tyder på att även när begränsningar av sprängskador inte tillämpas för drivning (dvs konturhålen är fulladdade), kan den resulterande skadan bli mindre än förväntat på grund av den vågdämpande effekten som det förspräckta berget utgör. På grund av den dämpande effekten, kommer dålig kontroll av kontursprängning att till vis del vara sälvkorrigerande. Det måste dock starkt betonas att väl en utvecklad utformning av sprängning med kontroll av konturen är mycket fördelaktig i förhållande till både ekonomiska och säkerhetsmässiga aspekter.

  • 1304.
    Thorbjörnson Lind, Thomas
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Jord- och bergmekanik.
    Rockfalls from rock cuts beside Swedish railroads: A full scale fieldtest, to investigate rockfalls and how rock bounces2016Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Rockfalls is a major problem around the world, if they occur in populated areas, they can cause major damage to infrastructure, injure or kill people. For this reason, it is important to be able to predict where the risk of rockfalls and how to prevent and protect populated areas from them. However, it is no easy task to predict rockfalls. Although if an area with potential area for rockfall is localized it may seem easy to construct protective meshing or bolting potential blocks down. But in many cases this is not easy to do due to practical issues or economic reasons, for example in rock cuts on older railways in Sweden. Fall heights from rock cuts like that are not particularly high but the risk of damage to the trains and infrastructure in the track area is high, however, it is unknown how extensive the damage may be. Trafikverket, the Swedish authority responsible for Sweden's roads and railways, has for some years investigated a new method for classifying and minimize the risk of rockfalls from rock cuts next to the railways. This study include aims to include the potential maximum distance of a block from the rockfall can travel to the existing method.

    This master's work is part of the investigation and will include full scale field test where the rockfalls are examined by filming them and then evaluate the “bounce coefficient”, coefficient of restitution, from the individual rockfalls using photogrammetric methods. During the field study, a geotechnical testing equipment, DCP test rig, to be evaluated for its ability of an easy way in the field to produce an estimated value on the coefficient of restitution. During the evaluation, two rockfall simulating software be used to investigate how well the results from them match the true blocks movements.

  • 1305.
    Toromanovic, Jasmina
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    On Parameter Identification for Better Predictions of Dam Behaviour2018Licentiatavhandling, med artikler (Annet vitenskapelig)
  • 1306.
    Toromanovic, Jasmina
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Laue, Jan
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Assessment of Arching and Cracking Potential by Numerical Modelling: A Case Study of the Mornos Dam2017Konferansepaper (Fagfellevurdert)
  • 1307.
    Toromanovic, Jasmina
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Mattsson, Hans
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Laue, Jan
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Use of parameters identified by inverse analysis in an earth- and rockfill dam application2017Inngår i: 85th Annual Meeting  of International Commission on Large Dams, 2017Konferansepaper (Fagfellevurdert)
  • 1308.
    Toromanovic, Jasmina
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Mattsson, Hans
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Sipola, Johanna
    ÅF Hydropower Industry.
    Effects on an earth and rockfill dam undergoing dam safety measures2016Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Over the lifetime of a dam several measures are usually taken in order to assure the stability and the performance of the dam. In this case a hydropower dam in Northern Sweden is in need of dam safety measures. The question arose, what consequences there might be when such measures are performed. In order to estimate these effects, simulations have been carried out in the finite element programme PLAXIS 2D. Thereby, the deformations and the stability of the dam for the planned work can be evaluated. The performed simulations are based upon previously conducted research at Luleå University of Technology, where soil parameters in the investigated dam were identified by a method of inverse analysis.Three sections have been analysed: A, B and C. In section A increasing pore water pressure has been observed at the downstream side of the dam. Thereby it has been concluded that a new drainage system is needed; new trenches of large size are to be excavated. In section B new toe berms are planned, due to the requirement that the dam should be able to divert leakage without erosion occurring at the dam toe. This contains soil material that might degrade when stresses are increased, with intensified deformations as a consequence. In section C a new berm is to be constructed, before this can be conducted an excavation is performed at the toe of the dam.The results have shown deformations of an acceptable magnitude and factors of safety that indicate conditions for the planned dam safety measures. Numerical values of deformations and factors of safety can be utilised as an attempt to establish alarm values for the stability of the dam. The finite element method is a useful tool for this kind of evaluation.

  • 1309.
    Toromanovic, Jasmina
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Mattsson, Hans
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Laue, Jan
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Effects of Measurement Error on the Genetic Algorithm in Soil Parameter Identification for an Earth- and Rockfill Dam2017Inngår i: ICSMGE 2017: 19th International Conference on Soil Mechanics and Geotechnical Engineering, 19th ICSMGE Secretariat , 2017, s. 2443-2446Konferansepaper (Fagfellevurdert)
    Abstract [en]

    It is usually difficult to determine values for soil parameter values in earth- A nd rockfill dams by traditional methods. Field sampling is not easily performed, especially in the impervious parts, since the performance and safety of the dam structure may be affected in an unfavourable way. Therefore other methods, preferably non-destructive, are needed to investigate the mechanical behaviour. Inverse analysis has been utilised to identify soil parameter values for an earth- A nd rockfill dam. An error function and a genetic search algorithm were combined with a finite element software to perform the analysis. The model parameters in the chosen constitutive model were calibrated until the horizontal deformations corresponded to the horizontal inclinometer deformations. Errors or irregularities in field measurements can occur, for instance based on the accuracy of the equipment. In this study, the performance of the genetic algorithm was investigated, when applied to identify soil parameters for a dam. Added perturbations to simulated inclinometer data are randomly generated within a chosen interval of error. The results showed that the genetic algorithm found a minimum for the error function even though the field data was substantially perturbed. Errors up to 10% were shown to have minor impact

  • 1310.
    Toromanovic, Jasmina
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Mattsson, Hans
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Laue, Jan
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Effects of random measurement error on the genetic algorithm in soil parameter identification for an earth- and rockfill dam2017Konferansepaper (Annet vitenskapelig)
  • 1311. Trouve, Emmanuel
    et al.
    Mercier, Gregoire
    Fauvel, Mathieu
    Bruzonne, Lorenzo
    Ban, Yifang
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geoinformatik.
    Foreword to the Special Issue on Analysis of Multitemporal Data and Applications2016Inngår i: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, ISSN 1939-1404, E-ISSN 2151-1535, Vol. 9, nr 8, s. 3356-3358Artikkel i tidsskrift (Annet vitenskapelig)
  • 1312.
    Tvinghagen, Adam
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Jord- och bergmekanik.
    Arching Stability in Shallow Tunnels: A comparison between analytical and numerous solutions2016Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
  • 1313.
    Umar, Sraj Banda
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Sjöberg, Jonny
    tasca Consultants AB, Luleå.
    Savilahti, Thomas
    Loussavaara-Kiirunavaara AB (LKAB) Malmberget Mine, Gällivare.
    Modelling of caving and deformation mechanisms of the hangingwall of the Printzsköld oreboby at Malmberget mine2017Inngår i: The Southern African Journal of Mining and Metallurgy, ISSN 2225-6253, E-ISSN 1543-9518, Vol. 117, nr 4, s. 351-360Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Sublevel caving in Malmberget mine results in mining-induced surfacedeformation. One of the currently mined orebodies is the Printzsköldorebody. As mining deepens there is need to assess the behaviour of thecave formed in the subsurface above this orebody. Numerical analysis wasused to assess the effects of extraction to deeper levels and performstrength parametric studies. Stress redistribution was studied, and theresults showed high stress buildups in the hangingwall and the crownpillar. Two failure mechanisms have been identified – shear and tensile.Reducing cohesion by 50% increased the area of the yielded zone by morethan 100% in the hangingwall.

  • 1314.
    Uotinen, Lauri
    et al.
    Aalto University, Finland.
    Korpi, Eero
    Aalto University, Finland.
    Hartikainen, Ari
    Aalto University, Finland.
    Yorke, Raphael
    Aalto University, Finland.
    Johansson, Fredrik
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE).
    Rinne, Mikael
    Aalto University, Finland.
    A method to downscale joint surface roughness and to create replica series using 3D printed molds2015Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In order to determine the in-situ shear strength of rock joints, large scale testing is required. However, this is both expensive and difficult to execute. One possible method to overcome this may be to use photogrammetry to capture large joint surface roughness in-situ and downscale it to replica samples, which could be sheared in laboratory. In this paper, as a first part in such a method, a technique to digitize surface roughness and to produce replica samples for laboratory shear testing from a larger joint sample are presented. First, a thin granitic rock slice with dimensions of 1.75 m x 0.95 m of granitic intact rock was chosen for the study. The joint surface is fresh and created through tensile induced splitting. The large joint sample is digitized using photogrammetry. Then, one full-scale 1.7 m x 0.6 m geometry is cropped from the digitized joint geometry and then subsamples at 10x, 7.5x, 5x, 2.5x and 1x scales. All sub-geometries are scaled down digitally to produce 0.17 m by 0.06 m geometries. The geometries are used to make casting molds both positive and negative to produce samples with perfect matedness. The casting molds are 3D printed in polylactic acid plastic and C60/75 concrete is cast to produce a replica series. In addition to the creation of this replica series, two pilot replicas are also tested using a portable shear box with a 0.5 MPa normal pressure. The results from the pilot rounds are presented and discussed. Finally, suggestions for future research are given.

  • 1315.
    Vahdati, Pooya
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    CFD simulation of water behavior in bottom outlet channel of Storfinnforsen dam2010Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    The focus of this project is to simulate the water behavior downstream of the Storfinnforsen dam, located in the centre of Sweden. Specifically, this will compare a simulation of the water in the curved channel after the bottom outlet to results obtained from hydraulic physical modeling tests carried out by Vattenfall R & D company at Älvkarleby laboratory. The parameters of velocity, depth of water while the gate is fully open and the variable level of water in the reservoir were compared with the velocity and depth parameters found in the physical model.

  • 1316.
    Vahdati, Pooya
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Identification of soil parameters in an embankment dam by mathematical optimization2014Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The finite element method (FEM) has been widely used to analyse earth and rockfill dams. In a finite element analysis a proper constitutive model has to be chosen for each part of the dam in order to simulate the relation between stresses and strains. The zones of an earth and rockfill dam have different functions. Because of that the zones normally consist of various soil types for which the stress/strain response could vary considerably. For each dam zone, suitable values have to be assigned to the parameters included in the constitutive model chosen. In general, laboratory tests and/or field tests of the soil are needed as a basis for this parameter evaluation. However, many dams are old and limited information might be available regarding the soil materials being used in the dam structures. In dams, it is normally very difficult to take up soil samples for testing, especially from the central impervious part, since this might affect the dam performance and the safety of the dam. For dams it would be advantageous if constitutive parameter values could be determined with some non-destructive method. Inverse analysis provides a possibility to determine the constitutive behaviour of different materials within the dam structure under the condition that the dams have been equipped with various instrumentations, for monitoring dam performance, which record data such as pore pressures, deformations, total stresses and seepage etc. In the method of inverse analysis, two separate parts are included: (1) an optimization method consisting of an error function and a search algorithm and (2) a numerical method to solve the partial differential equations arising in stress-strain analysis of structures. In this study, inverse analysis of a dam case was performed with a commercial finite element program Plaxis and the genetic algorithm was utilized as the search algorithm in the optimization method. The genetic algorithm was chosen due to its robustness and efficiency, particularly since it provides a set of solutions close to the optimum solution instead of one unique answer; a set of solutions is more practical from a geotechnical perspective. In the proposed inverse analysis a finite element model is calibrated automatically by changing the values of the input parameters of the selected constitutive model in different dam zones until the discrepancy between the measured results by dam instrumentations and the corresponding computed results is minimized.In order to examine the efficiency and robustness of the genetic algorithm, the research was initially focused on a synthetic case study. The synthetic case, a set of model parameters known in advance, is a good test of the mathematical basis used in the optimization, i.e. the objective function and the search algorithm. The Mohr-Coulomb model was chosen for all dam zones, as an initial choice for this research, chiefly because of its simplicity. A very good agreement for the optimization against the synthetic case was obtained. The practical outcome of an inverse analysis clearly depends on the ability of the constitutive models chosen to capture the real soil behaviour in the different dam zones. A proper choice of a constitutive model provides an opportunity to calibrate the finite element model properly. Therefore, in the next step the Hardening soil model, an advanced constitutive model, was chosen for optimization on the dam. In this part of the research, two cases (A and B) based on different reservoir water levels and number of berms constructed, were analysed. All the data of horizontal displacement were received from exactly the same positions in the geometry as the measurements carried out with the single inclinometer. The results of inverse analyses showed that the Hardening soil model is able to capture better the soil displacements within the dam structure, especially at the crest part, compared to the Mohr-Coulomb model.Finally, it was concluded that inverse analysis is a practical tool for identifying soil material properties of earth and rockfill dams and provides a non-destructive method for dam engineers to obtain more information about the dams. Moreover, if inverse analysis applications become available in commercial finite element software, it would certainly be a valuable tool for dam engineers assessing dam performance and dam safety.

  • 1317.
    Vahdati, Pooya
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Levasseur, Séverine
    Département ArGEnCo Service de Géomécanique et géologie de l'ingénieur Université de Liège.
    Mattsson, Hans
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Inverse Hardening Soil Parameter Identification of an Earth and Rockfill Dam by Genetic Algorithm Optimization2014Inngår i: The Electronic journal of geotechnical engineering, ISSN 1089-3032, E-ISSN 1089-3032, Vol. 19, nr N, s. 3327-3349Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper presents a study of identification of constitutive parameter values in the Hardening soil model by inverse analysis of an earth and rockfill dam application. The authors have experience from a previous study on the same case with the Mohr-Coulomb model. The objective of this research is to examine if the inverse analysis technique can be successfully used for this type of application and choice of constitutive model. The values of soil parameters are determined based on horizontal deformations obtained from installed instrumentations in the dam. The quantities that are monitored in the dam can be numerically predicted by a finite element simulation. In inverse analysis, constitutive parameter values are chosen in such a way that the error between data recorded by measurements in the dam and numerical simulation is minimized. An optimization method based on the genetic algorithm was applied to search for the minimum error in the search domain in this study. Optimizations have initially been performed in a large search domain in order to find a criterion identifying the best solutions. Thereafter, the optimizations were limited to this criterion in order to find the best set of solutions close to the optimum point. Moreover, the error function topology and smoothness was examined as well. It was overall concluded, that the inverse analysis technique could be effectively used for earth and rockfill dam applications, despite the fact that the technique is expensive in terms of computational time.

  • 1318.
    Vahdati, Pooya
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Levasseur, Séverine
    Département ArGEnCo Service de Géomécanique et géologie de l'ingénieur Université de Liège.
    Mattsson, Hans
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Inverse Mohr-Coulomb soil parameter identification of an earth and rockfill dam by genetic algorithm optimization2013Inngår i: The Electronic journal of geotechnical engineering, ISSN 1089-3032, E-ISSN 1089-3032, Vol. 18, nr X, s. 5419-5440Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper presents a study of identification of constitutive parameter values in the Mohr-Coulomb model by inverse analysis of an earth and rockfill dam application. The objective is to examine if the technique of inverse analysis can be effectively used for this type of case. The values of soil parameters are determined based on horizontal deformations recorded from installed instrumentations in the dam. The quantities that are monitored in the dam can be numerically predicted by a finite element simulation. In inverse analysis, constitutive parameter values are chosen in such a way that the error between data obtained by measurements in the dam and numerical simulation is minimized. An optimization method based on the genetic algorithm was utilized to search for the minimum error in this study. Optimizations have been performed against both a synthetic and a real dam case. The effect of the population size in the genetic algorithm was also analysed for this case in order to approach a proper set of solutions close to the optimum point by considering: the finite element computation time and the error function values. The error function topology was examined as well, and it was found to be complex and noisy for this application. The genetic algorithm is known to be a practically good choice of search method for such complicated topologies. It was overall concluded, that the inverse analysis technique studied, could be effectively used for this kind of earth and rockfill dam application despite the fact that, the technique is expensive in terms of computational costs. Inverse analysis has the potential to become a valuable tool for dam engineers assessing dam performance and dam safety if it becomes readily available in commercial finite element software.

  • 1319.
    Vahdati, Pooya
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Levasseur, Séverine
    Université de Liège.
    Mattsson, Hans
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Inverse soil parameter identification of an earth and rockfill dam by genetic algorithm optimization2013Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The paper presents a study of constitutive parameter value identification by inverse analysis on an earth and rockfill dam application. The objective is to examine if the technique of inverse analysis can be effectively used for this type of case. In the inverse analysis procedure discussed here, values of constitutive parameters are determined based on data recorded from installed instrumentations in the dam. The quantities that are monitored in the dam can be numerically predicted by a finite element simulation. To perform a finite element simulation, constitutive models have to be chosen and values have to be assigned to the parameters included. In inverse analysis, constitutive parameter values are chosen in such a way that the error between data obtained by measurements in the dam and numerical simulation is minimized. This is accomplished by optimization. The genetic algorithm was utilized as the optimization strategy, to search for the minimum error, in this study. Optimizations have been performed both against a synthetic dam case and a real dam case. It was concluded, that the inverse analysis technique studied, could be effectively used for this kind of earth and rockfill dam application. However, the technique was time consuming. Inverse analysis has the potential to become a valuable tool for dam engineers assessing dam performance and dam safety if it becomes readily available in commercial finite element software.

  • 1320.
    Viklander, Peter
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Compaction and thaw deformation of frozen soil: permeability and structural effects due to freezing and thawing.1997Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    This thesis is the result of the two projects:"Deformations in winter compacted soils" and "Permeability changes in a fine-grained till due to freeze/thaw". The aim of the first project was to study whether it is possible to compact frozen soils, in road embankments etc., to a satisfying result as well as to identify the most important factors influencing the compaction result. Different types of soil (fine-grained till and sand) were compacted in the laboratory at the temperatures +20, -2 and -10°C using compaction cylinders of two different sizes (1 dm³). Frozen soil cubes, having a side-length of 5 to 100 mm, were manufactured at different water contents and compacted in frozen state. The tests show that the compaction result decreases with decreasing temperature and increasing water content. However, the influence of the size of the soil cubes was of minor importance and the influence of the testing temperature was significantly smaller than what has been reported in the literature. In addition, compression tests on frozen, compacted soil samples were carried out to measure the thaw settlement. A relation ( a-value), based on the dry density of the frozen and unfrozen soil, was established from which it is possible to estimate the maximum compression taking place when the frozen soil thaws and is loaded. The aim of the second project was to investigate whether structural changes take place in a fine-grained till exposed to cyclic freezing and thawing. It was believed that freeze/thaw cycles could have a negative impact on fine-grained till, e.g. on its function as a hydraulic barrier. The permeability was chosen to be the key parameter to study whether the structure was affected of freezing and thawing or not. In addition, tests were directed to measure possible movements of small particles and stones due to freezing and thawing. In the laboratory, unfrozen soil was compacted to different void ratios into a rigid wall opermeameter and the permeability was measured. Thereafter, the sample was frozen and thawed a number of cycles. The samples were frozen one dimensionally in a closed pore water system and the permeability was measured in the thawed soil after a certain number of cycles. In addition, the particle movements were measured by granulometric tests and the stone movements by a specially developed X-ray technique. The investigations showed that the permeability in a fine-grained till is influenced by the freeze/thaw cycles. Typically, the permeability increased by 1 to 10 times in an initially dense till and decreased between 1 to 50 times in an initially loose till. The soil exhibited volume changes due to the freeze/thaw cycles and the volume typically decreased for an initially loose soil and increased for a dense soil. A residual void ratio was reached after 1-3 freeze/thaw cycles, independent of the state of the soil structure prior to freezing. The residual void ratio ranged from 0.31 to 0.40 in the studied material. Finally, no particle movements were detected, but significant stone movements in vertical as well horizontal direction were identified.

  • 1321.
    Viklander, Peter
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Compaction of frozen soils: a laboratory study1994Inngår i: Proccedings: Polartech '94 - International Conference on Development and Commercial Utilization of Technologies in Polar Regions, March 22-25, 1994 Luleå, Sweden, Luleå: Högskolan i Luleå , 1994, s. 109-Konferansepaper (Annet vitenskapelig)
  • 1322.
    Viklander, Peter
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Egenskaper hos jord packad under vinterförhållanden: en litteraturundersökning1992Rapport (Annet vitenskapelig)
  • 1323.
    Viklander, Peter
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Frusen jords packnings- och deformationsegenskaper1994Licentiatavhandling, monografi (Annet vitenskapelig)
  • 1324.
    Viklander, Peter
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Frysnings- och tiningscyklers inverkan på jords permeabilitet: en litteraturundersökning1995Rapport (Annet vitenskapelig)
  • 1325.
    Viklander, Peter
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Laboratory study of stone heave in till exposed to freezing and thawing1998Inngår i: Cold Regions Science and Technology, ISSN 0165-232X, E-ISSN 1872-7441, Vol. 27, nr 2, s. 141-152Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Cyclic freezing and thawing of soils affect the structure and might, under certain conditions, cause stones and particles to move and relocate. The movement of stones will influence the soil structure and create weak and loose parts with increased permeability. This phenomenon has been known for a long time, but the knowledge regarding the magnitude of stone heave and soil conditions necessary for heave to take place has been lacking. Therefore, laboratory tests were carried out. Fine-grained till (moraine) was compacted to different void ratios and then saturated in a rigid wall permeameter which was exposed to one-dimensional freezing and thawing in a closed water system. The movements of an embedded stone were measured by an X-ray technique. Unfrozen samples, as well as samples frozen and thawed, were X-rayed and the stone movements were quantified after 1, 2, 4, and 10 cycles of freezing and thawing. The results show that stone movements (vertical and horizontal) take place due to freeze/thaw. The void ratio (the ratio of the volume of void space to the volume of solid substance in the sample) was found to be a key parameter for whether upward or downward stone movements took place. The downward movement occurred when the soil had a high void ratio, and the upward when the void ratio was small. In the loose soil, the stone first moved downwards and then, when the soil became denser due to freeze/thaw, it changed direction and heaved. In the loose soil, significant movements in the horizontal direction as well as rotation of the stone were also found.

  • 1326.
    Viklander, Peter
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Permeability and volume changes in till due to cyclic freeze/thaw1998Inngår i: Canadian geotechnical journal (Print), ISSN 0008-3674, E-ISSN 1208-6010, Vol. 35, nr 3, s. 471-477Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A fine-grained nonplastic till was compacted in the laboratory in three types of rigid wall permeameters, having a volume of 0.4, 1.5, and 25 dm3, respectively, and, was thereafter exposed to a maximum of 18 freezing and thawing cycles. The permeabilities in the vertical direction of saturated samples were measured in unfrozen soil as well as in thawed soil. The results show that the permeabilities changed after freezing and thawing. The magnitude of the changes in this study were in the range 0.02-10 times after freeze/thaw compared with the unfrozen soil. Soil exhibited volume changes subsequent to freeze/thaw. The volume typically decreased for an initially loose soil and increased for a dense soil. Independent of whether the initial soil structure was loose or dense, a constant `residual' void ratio, eres, was obtained after 1-3 cycles. For the soil investigated, the residual void ratio ranged from 0.31 to 0.40

  • 1327.
    Viklander, Peter
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Eigenbrod, Dieter
    Lakehead University, Thunder Bay, Ontario.
    Stone movements and permeability changes in till caused by freezing and thawing2000Inngår i: Cold Regions Science and Technology, ISSN 0165-232X, E-ISSN 1872-7441, Vol. 31, nr 2, s. 151-162Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Vertical uplifting of boulders and stones is well known to take place in cold regions. Movements of stones in roads might lead to traffic danger, vehicle failures, and cause breakdown of the road surface with the need of expensive repair as a consequence. In addition, freeze/thaw and associated stone movements may cause an increase in permeability, which can lead to contamination of soils and ground water if used as soil liners in landfill areas or even dam failures if used as hydraulic barriers in earth dams. Freeze/thaw tests were carried out in the laboratory on a silty sandy soil in order to study movements of embedded stones and to measure how the overall permeability was influenced by freeze/thaw cycles. The soil samples were compacted at three different water contents, i.e. 11.5% (optimum), 14.5%, and 17.5%. Each sample contained one stone, placed at a predetermined depth. The soil samples were subjected to one-dimensional open system freeze/thaw. Soil temperatures, volume changes, and stone movements were measured. The results showed that upward stone movements took place due to freeze/thaw in the frost susceptible soil compacted at and 3% above the optimum water content. In addition, the permeability increased in samples with initial water contents of 11.5% and 14.5%. This permeability increase was as much as 81 times after six freeze/thaw cycles. For the samples with initial water contents of 17.5%, very small changes in permeability were measured. Vertical uplifting of boulders and stones is well known to take place in cold regions. Movements of stones in roads might lead to traffic danger, vehicle failures, and cause breakdown of the road surface with the need of expensive repair as a consequence. In addition, freeze/thaw and associated stone movements may cause an increase in permeability, which can lead to contamination of soils and ground water if used as soil liners in landfill areas or even dam failures if used as hydraulic barriers in earth dams. Freeze/thaw tests were carried out in the laboratory on a silty sandy soil in order to study movements of embedded stones and to measure how the overall permeability was influenced by freeze/thaw cycles. The soil samples were compacted at three different water contents, i.e. 11.5% (optimum), 14.5%, and 17.5%. Each sample contained one stone, placed at a predetermined depth. The soil samples were subjected to one-dimensional open system freeze/thaw. Soil temperatures, volume changes, and stone movements were measured. The results showed that upward stone movements took place due to freeze/thaw in the frost susceptible soil compacted at and 3% above the optimum water content. In addition, the permeability increased in samples with initial water contents of 11.5% and 14.5%. This permeability increase was as much as 81 times after six freeze/thaw cycles. For the samples with initial water contents of 17.5%, very small changes in permeability were measured. Vertical uplifting of boulders and stones is well known to take place in cold regions. Movements of stones in roads might lead to traffic danger, vehicle failures, and cause breakdown of the road surface with the need of expensive repair as a consequence. In addition, freeze/thaw and associated stone movements may cause an increase in permeability, which can lead to contamination of soils and ground water if used as soil liners in landfill areas or even dam failures if used as hydraulic barriers in earth dams. Freeze/thaw tests were carried out in the laboratory on a silty sandy soil in order to study movements of embedded stones and to measure how the overall permeability was influenced by freeze/thaw cycles. The soil samples were compacted at three different water contents, i.e. 11.5% (optimum), 14.5%, and 17.5%. Each sample contained one stone, placed at a predetermined depth. The soil samples were subjected to one-dimensional open system freeze/thaw. Soil temperatures, volume changes, and stone movements were measured. The results showed that upward stone movements took place due to freeze/thaw in the frost susceptible soil compacted at and 3% above the optimum water content. In addition, the permeability increased in samples with initial water contents of 11.5% and 14.5%. This permeability increase was as much as 81 times after six freeze/thaw cycles. For the samples with initial water contents of 17.5%, very small changes in permeability were measured.

  • 1328.
    Viklander, Peter
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Deformation and compaction of frozen soils1994Inngår i: Ground freezing 94: proceedings of the seventh International Symposium on Ground Freezing, Nancy, France, 24-28 October 1994 / [ed] Michel Fremond, Rotterdam: Balkema Publishers, A.A. / Taylor & Francis The Netherlands , 1994, s. 109-116Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Frozen soils compaction are understood to give fills with low densities. Thus, relatively large deformations often occur when such fills melts. The most important factors influencing the obtained dry density, and consequently the thaw deformations, are compaction effort, temperature, water/ice content and soil type. A laboratory investigation was conducted in order to quantify the different factors influencing the obtained degree of compaction, as well as related thaw deformation. The results indicated that the water content of the soil is the most important factor for the obtained dry densities and for the thaw compressions

  • 1329.
    Viklander, Peter
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Hur påverkas jord av frysning och tining2000Inngår i: Bygg & Teknik, ISSN 0281-658X, Vol. 92, nr 1, s. 59-61Artikkel i tidsskrift (Annet (populærvitenskap, debatt, mm))
  • 1330.
    Viklander, Peter
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Laboratoriepackning av frusen jord1995Inngår i: 12th Nordiska Geoteknikermötet, June 26-28, 1996, Reykjavik, Iceland, 1995, s. 159-168Konferansepaper (Annet vitenskapelig)
  • 1331.
    Viklander, Peter
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Laboratory study of the compaction properties of frozen soils1993Inngår i: Frost in geotechnical engineering: proceedings of the 2nd international symposium on Frost geotechnical engineering, Rotterdam: Balkema Publishers, A.A. / Taylor & Francis The Netherlands , 1993, s. 69-77Konferansepaper (Fagfellevurdert)
  • 1332.
    Viklander, Peter
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Permeability changes in a fine-grained till du to cycles of freezing and thawing1997Inngår i: Ground Freezing 97: frost action in soils : proceedings of the International Symposium on Ground Freezing and Frost Action in Soils / Luleå / Sweden / 15-17 April 1997 / [ed] Sven Knutsson, Rotterdam: Balkema Publishers, A.A. / Taylor & Francis The Netherlands , 1997, s. 193-202Konferansepaper (Fagfellevurdert)
  • 1333.
    Viklander, Peter
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Uppfrysning av block och stenar i vägar1999Inngår i: Bygg & Teknik, ISSN 0281-658X, Vol. 92, nr 1, s. 39-41Artikkel i tidsskrift (Annet (populærvitenskap, debatt, mm))
  • 1334.
    Viklander, Peter
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Magnusson, O.
    Luleå tekniska universitet.
    Laboratory compaction using an enlarged fall-weight apparatus1994Inngår i: Proceedings: Thirteenth International Conference on Soil Mechanics and Foundation Engineering, New Delhi/5-10 January, 1994 = Comptes rendus / Treizième Congrès international de mécanique des sols et des travaux de fondations, New Delhi/5-10 janvier, 1994, Rotterdam: Balkema Publishers, A.A. / Taylor & Francis The Netherlands , 1994, Vol. 1, s. 425-428Konferansepaper (Fagfellevurdert)
  • 1335.
    Vikström, Lars
    Luleå tekniska universitet.
    Uppmätta och beräknade tjällyftningar och tjäldjup i jord: en analys av ingångsparametrarnas betydelse för beräkningsresultatet1999Licentiatavhandling, monografi (Annet vitenskapelig)
    Abstract [sv]

    Målet med arbetet som ligger till grund för licentiatuppsatsen har varit att bestämma behovet av och omfattningen på fält- och laboratorieundersökningar för att erhålla tillförlitliga resultat från beräkningar med programmet Pc-heave. Utgångspunkten har varit att studera om man enbart med en enklare fält- och laboratorieundersökningar kan erhålla ingångsparametrar som ger tillräcklig noggrannhet vid predikteringen av tjällyftning och tjälnedträngning i en jord med hjälp av programmet Pc-heave. Syftet har varit att beräkningen skall vara en prognos och utföras utan att i efterhand behöva anpassa parametrarna för att uppnå överensstämmelse mellan beräknade och uppmätta värden på tjälnedträngning och tjällyftning. Med anpassning av sådana parametrar som, mängd ofruset vatten och permeabilitet, utifrån en kortare tids, en månads, observationer i inledningen av tjälningsperioden erhåller man god överensstämmelse mellan beräknade och uppmätta värden på tjällyftning, islinsernas läge och mäktighet och tjälnedträngningen. Islinsernas läge och mäktighet i den frusna jorden har detekterats med hjälp av röntgenfotografering av upptagna borrkärnor. Ingångsparametrar valda utifrån enklare undersökningar av typen kornfördelning, densitet, vattenkvot eller ytterligare parametrar bland annat ofrusetvatteninnehåll och permeabilitet bestämda i laboratorium ger däremot sämre resultat.

  • 1336.
    Vikström, Lars
    et al.
    Luleå University of Technology.
    Bernspång, Lars
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Strength and deformation behaviour of snow and snow structures: field and laboratory measurements at Icehotel Jukkasjärvi, Winter 2000 - 20012002Rapport (Annet vitenskapelig)
    Abstract [en]

    Density measurements, unconfined compression tests, creep tests, beam tests, and measurements of deformations were performed on snow and snow structures that formed the Icehotel during the winter 2000/2001. Results from the unconfined compression tests and creep tests showed that: At -5ºC unconfined compression strength was 0,598 MPa with a snow density of 532 kg/m3. Axial viscosity was 3,23·106 MPa-s and compactive viscosity was 5,24·106 MPa-s with a snow density of 524 kg/m3. At -10ºC unconfined compression strength was 0,681 MPa with a snow density of 558 kg/m3. Axial viscosity was 1,92·106 MPa-s and compactive viscosity was 1,38·106 MPa-s with a snow density of 518 kg/m3. At -11ºC unconfined compression strength was 0,879 MPa with a snow density of 550 kg/m3. Axial viscosity was 2,16·106 MPa-s and compactive viscosity was 2,79·106 MPa-s with a snow density of 470 kg/m3. Beam tests were performed on snow from a pile of artificially made snow. This type of snow was used to construct the arcs of the Icehotel. Results from the beam tests showed that the snow had a mean density of 510 kg/m3 and that Young's modulus E had a mean value of 335 MPa. At failure mean value of maximum tensile- and compression stress was 0,375 MPa and mean value of maximum shear stress was 0,039 MPa. During the winter 2000/2001 deformations of the church building were measured. Results show that the apex of the arcs actually rose 4 to 8 cm, though the shape of the arcs changed very little. Comparing results from this investigation with results from earlier investigations made on snow with similar densities showed that: Unconfined compression strength was 20 to 40 percent lower. Axial viscosity was similar in all but one test at -10/-11 ºC. Axial viscosity was in all tests higher at -5 ºC. Compactive viscosity was higher in all tests. Results from the beam tests regarding Young's modulus values and tensile strength showed similar results.

  • 1337.
    Vikström, Lars
    et al.
    Luleå tekniska universitet.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    A comparison between measured and calculated frost heave, frost penetration and formation of ice lenses1997Inngår i: Ground Freezing 97: frost action in soils : proceedings of the International Symposium on Ground Freezing and Frost Action in Soils, Luleå, Sweden, 15-17 April 1997 / [ed] Sven Knutsson, Rotterdam: Balkema Publishers, A.A. / Taylor & Francis The Netherlands , 1997, s. 297-305Konferansepaper (Fagfellevurdert)
  • 1338.
    Vranckx, Alexander
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Jord- och bergmekanik.
    Effect of heterogeneous densification due to vibroflotation on liquefaction resistance2017Independent thesis Advanced level (degree of Master (Two Years)), 30 poäng / 45 hpOppgave
  • 1339.
    Weber, Toni M.
    et al.
    Institute for Geotechnical Engineering, ETH Zurich.
    Laue, Jan
    Institute for Geotechnical Engineering, ETH Zurich.
    Springman, Sarah M.
    Institute for Geotechnical Engineering, ETH Zurich.
    Centrifuge modelling of sand compaction piles in soft clay under embankment load2006Inngår i: Physical Modelling in Geotechnics, 6th ICPMG'06: Proceedings of the 6th International Conference on Physical Modelling in Geotechnics, 2006, Vol. 1-2, s. 603-608Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Sand compaction piles are used in practice for ground improvement of soft subsoil in order to accelerate consolidation, reduce compressibility, and increase strength. The current design procedure of sand compaction piles is based on simple empirical calculations, which does not take full account of the sand pile behaviour. This research project investigates the behaviour of a base reinforced embankment constructed on a soft clay layer, which is improved with sand compaction piles. In order to gain a better understanding of interactions within the structure, physical investigations are being conducted by means of centrifuge modelling. Tests were performed under plane strain conditions in a strong box, using a newly developed sand compaction pile installation tool for in-flight pile construction. Initial analysis of test data shows the change in stress state due to sand compaction pile installation and the influence on clay behaviour. © 2006 Taylor & Francis Group, London.

  • 1340.
    Weber, Toni M.
    et al.
    Institute for Geotechnical Engineering, Swiss Federal Institute of Technology.
    Laue, Jan
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi. Institute for Geotechnical Engineering, Swiss Federal Institute of Technology.
    Springman, Sarah M.
    IInstitute for Geotechnical Engineering, Swiss Federal Institute of Technology.
    Modelling the inflight construction of sand compaction piles in the centrifuge2005Inngår i: Proceedings of the 16th International Conference on Soil Mechanics and Geotechnical Engineering: Geotechnology in Harmony with the Global Environment, 2005, Vol. 3, s. 1291-1294Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Sand compaction piles are used in practice for ground improvement of weak subsoil. These columnar inclusions improve the consolidation behaviour as well as reduce the compressibility of the soft ground. The current design procedure of these sand piles is based on simple empirical calculations, which does not fully take account of the sand pile behaviour. In order to gain a deeper understanding of the behaviour of sand compaction piles, physical and numerical investigations are being conducted. The basic system behaviour of soft soil and column is simulated physically by centrifuge modelling. Because the stress situation in the soil changes significantly due to installation, a sand compaction pile installation tool was developed and applied successfully in the first tests. This allowed the stress paths encountered by the soil during the construction process of a displacement sand pile to be modelled realistically. The results will be compared to real geometries and the behaviour is also studied numerically by means of finite element modelling. These findings provide the basis for further analysis of this geotechnical interaction problem extending the model by including geotextiles below embankments to be able to formulate some recommendations for the design procedure of sand compaction piles under embankments.

  • 1341.
    Weber, Toni M.
    et al.
    ETH Zurich, Institute for Geotechnical Engineeering, Studer Engineering, Institute for Geotechnical Engineering, Zurich.
    Plötze, Michael L.
    Institute for Geotechnical Engineering, ETH Zurich.
    Laue, Jan
    Institute for Geotechnical Engineering, ETH Zurich.
    Peschke, Gerd
    Institute for Geotechnical Engineering, ETH Zurich.
    Springman, Sarah M
    Institute of Geotechnical Engineering, ETH Hönggerberg, Zürich, Institute for Geotechnical Engineering, ETH Zurich.
    Smear zone identification and soil properties around stone columns constructed in-flight in centrifuge model tests2010Inngår i: Geotechnique, ISSN 0016-8505, E-ISSN 1751-7656, Vol. 60, nr 3, s. 197-206Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Stone columns are primarily used for the purpose of ground improvement in fine grained soils in order to reduce settlements and the risk of bearing failure. They are also designed to improve the drainage conditions in the ground and to accelerate the consolidation processes within the clay. However, smear and disturbing effects caused during the construction of stone columns result in degradation of consolidation performance in comparison with the theoretically ideal conditions. Model stone columns are constructed in-flight under 50 times gravity in centrifuge tests and the soil micro-structure in the vicinity of these columns is investigated by applying different methods, including environmental scanning electron microscopy and mercury intrusion porosimetry. The results these tests confirm that smear and disturbance occur owing to stone column installation and the region influenced can be divided into three sections: a penetration zone (1) where the sand particles are squeezed through the clay; a smear zone (2) where the soil particles have experienced a significant reorientation; and a densification zone (3) where the structure of the clay does not appear to change, but compaction of the clay is measurable. The extremes of the disturbed zone around model stone columns are determined to extend to about 2.5 times the column radius.

  • 1342.
    Wersäll, Carl
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Jord- och bergmekanik.
    Frequency Optimization of Vibratory Rollers and Plates for Compaction of Granular Soil2016Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Vibratory rollers are commonly used for compaction of embankments and landfills. This task is time consuming and constitutes a significant part of most large construction and infrastructure projects. By improving the compaction efficiency, the construction industry would reduce costs and environmental impact.

    This research project studies the influence of the vibration frequency of the drum, which is normally a fixed roller property, and whether resonance can be utilized to improve the compaction efficiency. The influence of frequency on roller compaction has not before been studied but the concept of resonance compaction has previously been applied successfully in deep compaction of fills and natural deposits.

    In order to examine the influence of vibration frequency on the compaction of granular soil, small-scale compaction tests of sand were conducted under varying conditions with a vertically oscillating plate. Subsequently, full-scale tests were conducted using a vibratory soil compaction roller and a test bed of crushed gravel. The results showed that resonance can be utilized in soil compaction by vibratory rollers and plates and that the optimum compaction frequency from an energy perspective is at, or slightly above, the coupled compactor-soil resonant frequency. Since rollers operate far above resonance, the compaction frequency can be significantly reduced, resulting in a considerable reduction in fuel consumption, environmental impact and machine wear.

    The thesis also presents an iterative equivalent-linear method to calculate the frequency response of a vibrating foundation, such as a compacting plate or the drum of a roller. The method seems promising for predicting the resonant frequency of the roller-soil system and can be used to determine the optimum compaction frequency without site- and roller-specific measurements.

  • 1343.
    Wersäll, Carl
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Jord- och bergmekanik.
    Influence of Frequency on Compaction of Sand in Small-Scale Tests2013Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Vibratory rollers are commonly used for compaction of embankments and landfills. In a majority of large construction projects, this activity constitutes a significant part of the project cost and causes considerable emissions. Thus, by improving the compaction efficiency, the construction industry would reduce costs and environmental impact. In recent years, rollers have been significantly improved in regard to engine efficiency, control systems, safety and driver comfort. However, very little progress has been made in compaction effectiveness. While the compaction procedure (e.g. layer thickness and number of passes) has been optimized over the years, the process in which the machine compacts the underlying soil is essentially identical to the situation in the 1970s.

    This research project investigates the influence of one crucial parameter, namely vibration frequency of the drum, which normally is a fixed roller parameter. Frequency is essential in all dynamic systems but its influence on the compaction efficiency has not been studied since the early days of soil compaction. Since laboratory and field equipment, measurement systems and analysis techniques at the time were not as developed as they are today, no explicit conclusion was drawn. Frequencyvariable oscillators, digital sensors and computer‐based analysis now provide possibilities to accurately study this concept in detail.

    In order to examine the influence of vibration frequency on the compaction of granular soil, small‐ scale tests were conducted under varying conditions. A vertically oscillating plate was placed on a sand bed contained in a test box. The experiments were carried out in laboratory conditions to maximize controllability. The first test setup utilized an electro‐dynamic oscillator where dynamic quantities, such as frequency and particle velocity amplitude, could be varied in real‐time. The second test setup included two counter‐rotating eccentric mass oscillators, where tests were conducted at discrete frequencies. This type of oscillator has a force amplitude that is governed by frequency.

    The main objectives of the tests were to determine the optimal compaction frequency and whether resonance can be utilized to improve compaction efficiency. Results showed that resonance had a major influence in the electro‐dynamic oscillator tests, where the applied force amplitude is low, and the optimal compaction frequency is the resonant frequency under these circumstances. In the rotating mass oscillator tests, where a high force was applied to the plate, resonant amplification was present but not as pronounced. Since force increase with frequency, the optimal frequency to obtain the highest degree of compaction is very large. In a practical regard, however, frequency should be kept as low as possible to minimize machine wear and emissions while still achieving a sufficient compaction of the soil. Considering the practical issues, it is proposed that surface compactors should operate slightly above the resonant frequency. However, the applicability to vibratory rollers must be confirmed in full‐scale tests.

    The thesis also presents an iterative method to calculate the frequency response of a vibrating plate, incorporating strain‐dependent soil properties. Calculated dynamic quantities are compared to measured values, confirming that the method accurately predicts the response.

  • 1344.
    Wersäll, Carl
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Jord- och bergmekanik.
    Bodare, Anders
    Geo Risk & Vibration Scandinavia.
    Massarsch, Rainer
    Geo Risk & Vibration Scandinavia.
    Frequency content of vertical ground vibrations caused by surface impact2012Konferansepaper (Fagfellevurdert)
  • 1345.
    Wersäll, Carl
    et al.
    Geo Risk & Vibration Scandinavia.
    Bodare, Anders
    Geo Risk & Vibration Scandinavia.
    Massarsch, Rainer
    Geo Risk & Vibration Scandinavia.
    Vibration Source Localization along Railway Tracks2012Inngår i: Noise and Vibration Mitigation for Rail Transportation Systems / [ed] T. Maeda et al., Berlin: Springer, 2012, s. 267-274Kapittel i bok, del av antologi (Fagfellevurdert)
    Abstract [en]

    Ground-borne vibration from railway traffic is an increasing problem in urbanized areas and measures are often needed to minimize its effects on the environment. An important question when dealing with railway problems is to identify the source(s) of vibration emitted along the railway track. Once this information is available, it is often possible to mitigate the problem by improving stiffness of the railway track and/or to upgrade worn-out or damaged rail sections and turnouts. This paper describes a method which makes it possible to determine the locations of track sections which are likely to emit strong ground vibration. A purpose-built track-bound vehicle which can be vibrated continuously at different frequencies can identify track sections having unfavorable dynamic foundation conditions. A theoretical concept is proposed to calculate the potential of energy emission from the vehicle moving along the track. Further, an innovative method is presented which makes it possible to determine the location of vibration sources by measurement of ground vibrations from existing railway traffic. This information can be used to determine the location of track sections where remedial measures are needed. Results are presented, illustrating application of the concepts, which can also be applied to other types of vibration problems.

  • 1346.
    Wersäll, Carl
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Jord- och bergmekanik.
    Larsson, Stefan
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Jord- och bergmekanik.
    Influence of force ratio and frequency on vibratory surface compaction2016Inngår i: Geotechnics for Sustainable Infrastructure Development / [ed] Phung Duc Long, 2016Konferansepaper (Fagfellevurdert)
  • 1347.
    Wersäll, Carl
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Jord- och bergmekanik.
    Larsson, Stefan
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Jord- och bergmekanik.
    Small-Scale Testing of Frequency-Dependent Compaction of Sand Using a Vertically Vibrating Plate2013Inngår i: ASTM geotechnical testing journal, ISSN 0149-6115, E-ISSN 1945-7545, Vol. 36, nr 3, s. 394-403Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 1348.
    Wersäll, Carl
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Jord- och bergmekanik.
    Larsson, Stefan
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Jord- och bergmekanik.
    Bodare, Anders
    Dynamic response of vertically oscillating foundations at large strain2014Inngår i: Computer Methods and Recent Advances in Geomechanics - Proceedings of the 14th Int. Conference of International Association for Computer Methods and Recent Advances in Geomechanics, IACMAG 2014 / [ed] Oka, Murakami, Uzuoka & Kimoto, CRC Press, 2014, s. 643-647Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A method for calculating the dynamic response of a vertically oscillating foundation on soil with strain-dependent properties is developed. Strain-dependent stiffness and damping are incorporated by an iterative procedure, presenting the response in frequency domain. The calculated dynamic displacement amplitudes are compared to small-scale tests using a vertically oscillating plate. The calculated dynamic quantities agree well with measured amplitudes over a wide frequency range.

  • 1349.
    Wersäll, Carl
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Jord- och bergmekanik.
    Larsson, Stefan
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Jord- och bergmekanik.
    Rydén, Nils
    Lund Universitet.
    Nordfelt, Ingmar
    Dynapac.
    Frequency Variable Surface Compaction of Sand Using Rotating Mass Oscillators2015Inngår i: ASTM geotechnical testing journal, ISSN 0149-6115, E-ISSN 1945-7545, Vol. 38, nr 2, s. 198-207Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 1350.
    Wersäll, Carl
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Jord- och bergmekanik.
    Massarsch, Rainer
    Geo Risk and Vibration Scandinavia AB.
    Soil Heave Due to Pile Driving in Clay2013Inngår i: Sound Geotechnical Research To Practice: Honoring Robert D.Holtz  II / [ed] Armin W. Stuedlein, and Barry R. Christopher, American Society of Civil Engineers (ASCE), 2013, s. 481-499Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Soil heave due to pile driving in clay is discussed and, in particular, its influence on adjacent piles. Finite element studies and results of model tests are presented and compared with field measurements. It is demonstrated that in the vicinity of the driven pile, the soil is displaced mainly in the lateral direction, similar to soil subjected to passive earth pressure. General rules of estimating soil heave inside and outside a pile group are examined. A method is proposed for estimating soil heave when driving a group of piles. Practical application of predicting soil heave is illustrated by an example.

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