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  • 1.
    Knutsson, Roger
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Viklander, Peter
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Knutsson, Sven
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Benefits of Advanced Constitutive Modeling when Estimating Deformations in a Tailings Dam2018In: Journal of Earth Sciences and Geotechnical Engineering, ISSN 1792-9040, E-ISSN 1792-9660, Vol. 8, no 1, p. 1-19Article in journal (Refereed)
    Abstract [en]

    Behavior of tailings dams are often controlled in dam surveillance programs where horizontal deformation is one of the key aspects. When evaluating field data, there is a necessity for comparison with anticipated deformations in order to relate field behavior to dam stability. With numerical modeling, these predictions can be made. This paper presents a case where horizontal deformations in a tailings dam have been simulated for a six-year period, using two-dimensional finite element modeling. Yearly dam raises have been simulated as staged constructions according to activities at site. Tailings materials have been simulated with an elasto-plastic constitutive model with isotropic hardening, called Hardening Soil and the conventional linear-elastic, perfectly plastic Mohr-Coulomb model. Soil parameters used for input were calibrated to laboratory data. Results from simulations were compared with data obtained in situ by a slope inclinometer. Results obtained by the Hardening Soil model indicate good agreement with respect to field measurements. However, this was not reached with the Mohr-Coulomb model. The results presented indicate benefits by using an advanced constitutive model for tailings in order to estimate in situ deformations in a tailings dam. The methodology presented can be used for prediction of future deformations, in order to relate the dam behavior to its stability. This is important in dam safety assessment, and will lead to a better understanding of the dam safety, being of great importance for the dam owner and the society in general.

  • 2.
    Knutsson, Roger
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Viklander, Peter
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Knutsson, Sven
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Stability considerations for thickened tailings due to freezing and thawing2016In: Paste 2016: Proceedings of the 19th International Seminar on Paste and Thickened Tailings / [ed] Sergio Barrea & Richard Jewell, Santiago: GECAMIN, 2016, p. 567-577Conference paper (Refereed)
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    Stability considerations for thickened tailings due to freezing and thawing
  • 3.
    Knutsson, Roger
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Viklander, Peter
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Knutsson, Sven
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    The use of numerical modelling in alert level set-up for instrumentation in tailings dams2015Conference paper (Refereed)
    Abstract [en]

    In dam safety operations for tailings dams, instrumentation has a major role. High pore-water pressure or large deformations can both be observed with good monitoring programs, and are covered in many dam safety guidelines. A key aspect when evaluating field data is the way to compare values with expected dam behavior (including a certain safety margin). This is needed in order to determine the safety of a dam, but there is lack of methods for this in the dam industry. With the use of finite element modeling, the behavior and stability of tailings dams can be simulated. Simulated behavior can be used in dam safety operations, where field data is compared with numerical results. In this paper, a case study is presented where a method for instrumentation alarm-level set-up is proposed.

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  • 4.
    Knutsson, Roger
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Viklander, Peter
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Knutsson, Sven
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Laue, Jan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Geothermal study to explain man-made permafrost in tailings with raised surface2018In: Environmental Earth Sciences, ISSN 1866-6280, E-ISSN 1866-6299, Vol. 77, no 7, article id 288Article in journal (Refereed)
    Abstract [en]

    Deposition of mine tailings in a cold climate requires precautions as temporary sub-zero temperatures can imply considerable consequences to the storage due to creation of permafrost. The risk of creating man-made permafrost lenses due to tailings deposition exists even in regions with no natural permafrost, as material being frozen during winter might not fully thaw by the following summer. When such frozen layers thaw during later longer warmer periods, excess pore water pressure and large settlements might develop. Such implications close to the dam structure have to be avoided and therefore the risk of generating permafrost should be reduced. This paper describes a geothermal model for one-dimensional heat conduction analysis. The model is able to simulate the temperature profile in tailings where the surface elevation is constantly increased due to deposition. At the tailings surface, the boundary condition is the air temperature changing over time during the year. Air temperatures, tailings deposition schedule and tailings properties are given as input to the model and can easily be changed and applied to specific facilities. The model can be used for tailings facilities in cold regions, where the effects of tailings deposition on the temperature regime are of interest. Findings can improve tailings management by explaining man-made permafrost generation. The model can also aid in setting up appropriate deposition schedules and to prevent generation of permafrost layers.

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    fulltext
  • 5.
    Knutsson, Roger
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Viklander, Peter
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Knutsson, Sven
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Laue, Jan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    How to avoid permafrost while depositing tailings in cold climate2018In: Cold Regions Science and Technology, ISSN 0165-232X, E-ISSN 1872-7441, Vol. 153, p. 86-96Article in journal (Refereed)
    Abstract [en]

    Managing tailings deposition in cold climate requires specific measures not to create permafrost. The risk of generating permafrost due to tailings deposition exists even in regions where permafrost would naturally not occur. Material being frozen during winter might not fully thaw in the following summer due to added height of the tailings on the surface. Such embedded layers of permafrost should be avoided especially close to tailing dams. Main reasons are to prevent impermeable layers in tailings facilities, and to reduce the risk of having implications if such layers thaw during warmer summers causing increase in pore water pressure, reduced effective stress, and increased water content.

    This paper presents a numerical study on the effects of tailings deposition in cold regions in relation to the potential formation of permafrost. Various deposition rates, schedules and tailings properties were evaluated. One-dimensional heat conduction analyses were performed with a temperature scenario representing a mine district in northern Sweden. Results show, that the thickness of permafrost layers increase with increased deposition rate and with increased water content. It was also shown that wet and loose tailings must be deposited in short periods during summer to avoid permafrost generation. In the case of dry and dense tailings more time is available for deposition in order not to cause aggradation of permafrost in the deposit.

    These findings can help mining operation to set up deposition schedules for tailings facilities in cold climate. For known tailings properties, results can be used to identify periods of the year when, and how much, tailings can be deposited in critical areas of a deposit in order to avoid permafrost formation.

  • 6.
    Knutsson, Sven
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Viklander, Peter
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Hur påverkar geotekniska borrmetoder omkringliggande jordmaterial?: Jämförelse av några borrningsmetoders påverkan via fullskaleförsök i Malmberget.2013In: Bygg & Teknik, ISSN 0281-658X, no 1, p. 43-45Article in journal (Other academic)
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  • 7.
    Knutsson, Sven
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Viklander, Peter
    Kujala, Kauko
    Oulu University of Technology.
    Permeability changes in soil liners due freezing and thawing1998In: Proceedings of the Symposium on Microstructural modelling og natural and artifically prepared clay soils with special emphasis on the use of clays for waste isolation: Lund, 12-14 October 1998 / [ed] Roland Pusch, Lund, 1998, p. 94-102Conference paper (Refereed)
  • 8.
    Moghadas, Shahab
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Perttu, Anna-Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Viklander, Peter
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Marsalek, Jiri
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Viklander, Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Laboratory study of infiltration into two frozen engineered (sandy) soils recommended for bioretention2016In: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 30, no 8, p. 1251-1264Article in journal (Refereed)
    Abstract [en]

    Infiltration of water into two frozen engineered soils of different gradation was studied in laboratory soil columns 1.2 m long and 0.1 m in diameter. Prior to testing, the soil moisture was adjusted to two levels, described by the gravimetric water content of 5 or 10%, soils were compacted to about 80-90% of the maximum dry density, and refrigerated to temperatures ranging from −8 to −2 °C. Water with temperatures 8-9 °C was thereafter fed on the top of columns at a constant head and the times of water break through the column and reaching a steady percolation rate, as well as the percolation rate, were recorded. The soil water content was a critical factor affecting the thawing process; during freezing, soil moisture was converted into ice, which blocked pores, and its melting required high amounts of energy supplied by infiltrating water. Hence, the thawing of soils with higher initial water content was much slower than in lower moisture soils, and water breakthrough and the attainment of steady percolation required much longer times in higher moisture soils. Heat transfer between infiltrating water, soil ice and frozen soil particles was well described by the energy budget equations, which constitute a parsimonious model of the observed processes. The finer grained soil and more compacted soil columns exhibited reduced porosity and required longer times for soil thawing. Practical implications of study results for design of bioretention facilities (BFs) in cold climate include the use of coarse engineered soils and fitting BFs with a drain facilitating soil drainage before the onset of freezing weather. This article is protected by copyright. All rights reserved.

  • 9.
    Rönnqvist, Hans
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Fannin, Jonathan
    Viklander, Peter
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    On the use of empirical methods for assessment of filters in embankment dams2014In: Geotechnique Letters, E-ISSN 2045-2543, Vol. 4, no oct-dec, p. 272-282Article in journal (Refereed)
    Abstract [en]

    A database of 80 embankment dams has been compiled that includes 23 dams that are reported to have experienced some form of internal erosion. An assessment is made of the potential for seepage-induced internal instability of the filter zone in all dams, using five empirical criteria for shape analysis of the grain size distribution curve. Similarly, an assessment is made of the likelihood of core–filter incompatibility in all of the dams, using an empirical criterion for excessive erosion. These two attributes of a filter gradation, namely its potential for internal instability and its capacity for soil retention, are combined in a unified plot. Evaluation of the database reveals a correlation between the attributes of a filter gradation and deficiencies that are attributed to internal erosion. The finding implies the unified plot may serve as a preliminary screening tool in engineering practice.

  • 10.
    Rönnqvist, Hans
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Fannin, Jonathan
    University of British Columbia.
    Viklander, Peter
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    The unified plot approach for assessing internal erosion: A case study of the Grundsjön dam sinkhole event2015Conference paper (Refereed)
    Abstract [en]

    The unified plot approach combines two attributes of a filter gradation, namely its potential for internal instability and its capacity for soil retention. Comparison to the performance of 80 existing embankment dams that includes 23 dams which are reported to have experienced some form of internal erosion, these attributes of the filter have been found to correlate with deficiencies related to internal erosion. Thus, in engineering practice, the unified plot may serve as a screening tool for internal erosion susceptibility. The Grundsjön dam, located on the river Ljusnan in Sweden, suffered a sinkhole event in 1990, 18 years after commissioning. In depth examination of the damaged stretch of the dam conducted in 1990 to 1991 revealed that internal erosion had indeed occurred; signs e.g., cavities in the core and filter devoid of fines suggest the process had initiated and been allowed to continue to the point that a sinkhole formed on the crest. Analysis of 43 as-placed filter gradations extracted from the Grundsjön dam filter envelope indicates that the filter is potentially unstable, although, not excessively coarse in terms of base soil retention. These results, as seen separately, provide relatively little explanation as to why the filter ultimately was unable to arrest the internal erosion process. However, combined, in the framework of the unified plot, it is readily apparent that the Grundsjön dam filter gradations distribute where dams with probable occurrence of internal erosion characteristically plot. Thus, the unified plot provides a plausible explanation for the internal erosion process that occurred. Indeed, reverse engineering the potential internal instability of the coarse filter gradation indicates that once changed by suffusion due to internal instability it potentially becomes a filter permitting excessive erosion.

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  • 11.
    Rönnqvist, Hans
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Fannin, Jonathan
    University of British Columbia, Vancouver.
    Viklander, Peter
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Wang, Lei
    Xi'an University of Technology.
    Discussion: On the use of empirical methods for assessment of filters in embankment dams2015In: Geotechnique Letters, E-ISSN 2045-2543, Vol. 5, no July-September, p. 140-141Article in journal (Refereed)
    Abstract [en]

    We first give consideration to the question that Wang, Yang and Ye pose on the distribution of data points in Fig. 4a and 4b of the paper under discussion, because it addresses an informative point that we believe may indeed benefit from a note of clarification. An assessment of the potential for seepage-induced internal instability in, for example, the filter material of a dam usually involves an evaluation of gradation curves obtained from construction records and any subsequent investigations. If more than one empirical method is used for shape analysis of the gradations, then several most-vulnerable curves may be identified from the analyses, owing to the empirical origins of the methods themselves.

  • 12.
    Rönnqvist, Hans
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Viklander, Peter
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    A unified-plot approach for the assessment of internal erosion in embankment dams2016In: International Journal of Geotechnical Engineering, ISSN 1938-6362, E-ISSN 1939-7879, Vol. 10, no 1, p. 66-80Article in journal (Refereed)
    Abstract [en]

    Surpassed only by overtopping as the larger contributor to the failure of embankment dams, internal erosion occurs when fine-grained particles are allowed to erode by the action of seepage. A dam may be susceptible to internal erosion if there are erodible surfaces not protected by filters. Signs of internal erosion of dams may be sinkhole formations, increased seepage and muddy discharge. Most methods to assess potential susceptibility are empirically based with little or no comparison to field experience. Based on a database of 80 embankment dams that includes 23 dams reported to have experienced some form of internal erosion and exhibited signs of internal erosion, analysis indicates a correlation between dams with internal erosion and characteristics of the filter of a dam. From comparison to field experience, an approach to assessing existing dams and internal erosion is proposed in this paper by combining attributes of filter gradation in a unified plot, namely its internal stability and its capacity for soil retention. The unified plot may serve as a preliminary screening tool for the susceptibility of internal erosion of dams.

  • 13.
    Rönnqvist, Hans
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Viklander, Peter
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Applying empirical methods to assess the internal stability of embankment dam cores of glacial till2015In: Geomaterials, ISSN 2161-7538, E-ISSN 2161-7546, Vol. 5, p. 1-18Article in journal (Refereed)
    Abstract [en]

    This paper presents a database of glacial till gradations that were compiled from laboratory in-ternal stability tests from the literature and from core soils of existing dams, some of which have experienced internal erosion. The potential internal instability of these gradations is assessed using empirical methods. Two approaches of evaluation are used: the Kenney-Lau method, which analyzes the shape of the gradation curve; and the Burenkova method, which uses factors of uniformity of the slope of the gradation. Although they include some uncertainties in terms of soils with fines, these methods, which were primarily developed from laboratory studies of sand and gravels, are used in engineering practice to evaluate widely graded soils that include fines, such as glacial tills. This study evaluates the glacial till gradations of the database using these approaches and discusses their applicability and relative predictive success. This study indicates that both the Kenney-Lau method and the Burenkova method have merit, but a closer analysis indicates that the Kenney-Lau approach has better predictive ability in terms of glacial tills.

  • 14.
    Rönnqvist, Hans
    et al.
    RQV Teknik AB, Hudiksvall.
    Viklander, Peter
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Effects of suffusion in embankment dam filters2016In: Dams and Reservoirs, ISSN 1368-1494, E-ISSN 1756-8404, Vol. 26, no 3, p. 118-125Article in journal (Refereed)
    Abstract [en]

    This study investigates how varying degrees of internal instability of silt–sand–gravel soils affect the grading characteristics due to suffusion. Suffusion is an initiation mechanism of internal erosion, which is a major cause of the failure of embankment dams. A database comprising gradations representative of those used for embankment dam filters has been compiled. Three are based on downward seepage tests by the authors and the remaining 23 are based on reported results of tests published by others. These 26 gradations are cohesionless sand–gravel soils and silt–sand–gravel soils with < 15% fines, some of which have slightly plastic fines. Internal stability is evaluated using two empirical criteria for shape analysis of the particle size distribution curve. By relating the internal stability to typical grading characteristics, the effects of internal instability are determined. Gradually, more severe effects are observed as the internal instability increases. For clearly unstable soils, with a stability index (H/F)min < 0·5 and a probability of internal instability pinitial > 70%, the effective grain size D15 is increased, on average, by a factor of 9 relative to its initial value. Coarsening of a critical filter to an impervious dam core may adversely affect the filter's protective ability.

  • 15.
    Rönnqvist, Hans
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Viklander, Peter
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Extending the Kenney-Lau method to dam core soils of glacial till2014In: Geotechnical News, ISSN 0823-650X, E-ISSN 2052-6156, Vol. 1, no 2, p. 73-87Article in journal (Refereed)
    Abstract [en]

    The Kenney-Lau method to assess internal stability of granular soils is in engineering practice stretched to include soils with fines. This strays beyond the method’s intended range and may introduce potential uncertainty in terms of validity. Herein, results are presented from the assessment of grain size curves from core construction data belonging to a large number of existing dams with core material composed of widely graded glacial till soils. Some have experienced internal erosion events and others have not, and based on the benchmark of historic performance data of these dams, the validity of the Kenney-Lau method in terms of glacial tills is investigated. Only dams in the same filter coarseness range are studied in order to reduce the influence of the filter. By contrasting dams with documented internal erosion history against the application results of the method, it indicates that the Kenney-Lau method with caution can be extended to include glacial till cores if within proposed fines content and finer fraction ranges.

  • 16.
    Rönnqvist, Hans
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Viklander, Peter
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Laboratory testing of internal stability of glacial tills: a review2014In: The Electronic journal of geotechnical engineering, ISSN 1089-3032, E-ISSN 1089-3032, Vol. 19, no V, p. 6315-6336Article in journal (Refereed)
    Abstract [en]

    Suffusion is an initiation mechanism of internal erosion. A soil susceptible to suffusion is internally unstable. In such a soil there is an imbalance between the finer fraction and the coarser, allowing for non-structural fine-grained particles in between fixed structural coarser grains. Thus, the fines may migrate which initiate internal erosion. This paper discusses internal stability of soils in general, and glacial till bases in particular, and reviews available laboratory testing in the literature on this type of soil. The laboratory set-up, characteristics of soils tested, soil preparation and boundary conditions are among the aspects discussed. The paper concludes with recommendations for further research in terms of glacial tills and internal stability testing.

  • 17.
    Rönnqvist, Hans
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Viklander, Peter
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    On the Kenney-Lau approach to internal stability evaluation of soils2014In: Geomaterials, ISSN 2161-7538, E-ISSN 2161-7546, Vol. 4, no 2, p. 129-140Article in journal (Refereed)
    Abstract [en]

    A commonly used approach to evaluating the potential for internal instability in soils is that of Kenney and Lau. This method involves a shape analysis of the grain size curve over a length of the soil’s finer part. A soil that is internally unstable has a particle size distribution with a finer fraction less than the coarser fraction; therefore, the coarser fraction makes up the primary fabric ofthe material. Thus, the fine-grained particles are loose (non-structural) in between fixed (structural) coarser grains, and these loose fine particles are permitted to migrate through the constrictions of the fabric of the coarser fraction. This paper discusses the evolution of the Kenney-Lau method and its boundary relations, and furthermore, a discussion on adaptations of the method, which touches on field experience and engineering practice, is given.

  • 18.
    Rönnqvist, Hans
    et al.
    RQV Teknik AB.
    Viklander, Peter
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Knutsson, Sven
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Experimental Investigation of Suffusion in Dam Core Soils of Glacial Till2017In: ASTM geotechnical testing journal, ISSN 0149-6115, E-ISSN 1945-7545, Vol. 40, no 3, p. 426-439Article in journal (Refereed)
    Abstract [en]

    The main objectives of this study were to determine the susceptibility to suffusion of widely graded, non-plastic glacial till; to identify potential factors influencing susceptibility; and conversely, to determine grading characteristics that potentially eliminate suffusion susceptibility. A laboratory experimental program was performed on 12 non-plastic glacial till specimens. Four were natural glacial tills sourced from the cores of four existing embankment dams in Sweden, and the remaining eight were mixtures based on these tills with adjusted particle size distributions to obtain target gradations. Four specimens failed by suffusion. By comparing against stable specimens, these were characterized by fines content <20 %, sand fraction <25 %, and finer fraction <30 %. Conversely, gradations with higher fines content (> 25 %), which in this study corresponds to finer fraction >35 %, may provide additional limits to suffusion susceptibility of this kind of soil.

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  • 19.
    Silva, Ingrid
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Lindblom, Jenny
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Viklander, Peter
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Laue, Jan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Assessment of internal erosion in the glacial till core of a Swedish dam2017Conference paper (Refereed)
    Abstract [en]

    Zoned embankment dams are a common type of dam in Sweden consisting of an impermeable central glacial till core flanked by zones of filter materials and rockfill shoulders. Dams with internal unstable core material allow fine particles to be transported by seepage, which may result in leakage paths and pore-pressure variations. These last two conditions are signs of initiated internal erosion. However, the effectiveness of the filter zone determines if the internal erosion will continue or not. This paper presents the assessment of internal erosion susceptibility of the glacial till core of a hydropower dam located in northern Sweden. The dam has experienced historical damages mainly in the form of sinkhole and leakage related to internal erosion. The study includes the analysis of the particle size distribution of samples obtained from boreholes, as well as a comparison of the geotechnical properties of the core with the Swedish dam safety guidelines available both during the dam construction in 1958 and today. The capability of the filter to stop the erosion process is not investigated.The results show that a well designed and constructed dams can be affected by local layers of internally unstable (suffusive) material susceptible to internal erosion.

    The capability of the filter to stop the erosion process is not investigated.The results show that a well-designed and constructed dams can be affected by local layers of internally unstable (suffusive) material susceptible to internal erosion.

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    Silva et al. (2017)_ ICOLD 2017
  • 20.
    Silva, Ingrid
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Viklander, Peter
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Laue, Jan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Effects of Void Ratio and Hydraulic Gradient on Permeability and Suffusion of Glacial Till Cores2018In: Internal Erosion in Earthdams, Dikes and Levees: Proceedings of EWG‐IE 26th Annual Meeting 2018 / [ed] Stéphane Bonelli, Cristina Jommi, Donatella Sterpi, Cham: Springer, 2018, p. 98-109Conference paper (Refereed)
    Abstract [en]

    Dams with core of broadly graded glacial moraines (tills) exhibit signs of internal erosion by suffusion to a larger extent than dams constructed with other types of materials, as reported by Sherard (1979). Garner and Fannin (2010) indicated that internal erosion initiates when an unfavorable combination of soil material, stress conditions and hydraulic load occur. A laboratory program, carried out at Luleå University of Technology (LTU), aims to study the effects of void ratio and hydraulic gradient on the initiation of suffusion of glacial till. It consists of suffusion tests conducted in permeameters with an inner diameter 101.6 mm and a height of 115 mm. Results show, as expected, that the hydraulic conductivity is lower with lower void ratio. Nevertheless, as the hydraulic gradient increases, the hydraulic conductivity reaches steady values. Changes in the hydraulic conductivity suggest variation in the initial void ratio due to detachment of the finer particles from the soil matrix. These fine particles start clogging the lower layers, therefore the rate of water flow decreases and so does the hydraulic conductivity. The hydraulic gradient for which the hydraulic conductivity reaches steady values is considered as the upper limit without suffusion evolved.

  • 21.
    Viklander, Peter
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Compaction and thaw deformation of frozen soil: permeability and structural effects due to freezing and thawing.1997Doctoral thesis, comprehensive summary (Other academic)
    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.

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  • 22.
    Viklander, Peter
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Compaction of frozen soils: a laboratory study1994In: 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, p. 109-Conference paper (Other academic)
  • 23.
    Viklander, Peter
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Egenskaper hos jord packad under vinterförhållanden: en litteraturundersökning1992Report (Other academic)
  • 24.
    Viklander, Peter
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Frusen jords packnings- och deformationsegenskaper1994Licentiate thesis, monograph (Other academic)
  • 25.
    Viklander, Peter
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Frysnings- och tiningscyklers inverkan på jords permeabilitet: en litteraturundersökning1995Report (Other academic)
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  • 26.
    Viklander, Peter
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Laboratory study of stone heave in till exposed to freezing and thawing1998In: Cold Regions Science and Technology, ISSN 0165-232X, E-ISSN 1872-7441, Vol. 27, no 2, p. 141-152Article in journal (Refereed)
    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.

  • 27.
    Viklander, Peter
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Permeability and volume changes in till due to cyclic freeze/thaw1998In: Canadian geotechnical journal (Print), ISSN 0008-3674, E-ISSN 1208-6010, Vol. 35, no 3, p. 471-477Article in journal (Refereed)
    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

  • 28.
    Viklander, Peter
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Eigenbrod, Dieter
    Lakehead University, Thunder Bay, Ontario.
    Stone movements and permeability changes in till caused by freezing and thawing2000In: Cold Regions Science and Technology, ISSN 0165-232X, E-ISSN 1872-7441, Vol. 31, no 2, p. 151-162Article in journal (Refereed)
    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.

  • 29.
    Viklander, Peter
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Knutsson, Sven
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Deformation and compaction of frozen soils1994In: 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, p. 109-116Conference paper (Refereed)
    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

  • 30.
    Viklander, Peter
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Knutsson, Sven
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Hur påverkas jord av frysning och tining2000In: Bygg & Teknik, ISSN 0281-658X, Vol. 92, no 1, p. 59-61Article in journal (Other (popular science, discussion, etc.))
  • 31.
    Viklander, Peter
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Knutsson, Sven
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Laboratoriepackning av frusen jord1995In: 12th Nordiska Geoteknikermötet, June 26-28, 1996, Reykjavik, Iceland, 1995, p. 159-168Conference paper (Other academic)
  • 32.
    Viklander, Peter
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Knutsson, Sven
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Laboratory study of the compaction properties of frozen soils1993In: Frost in geotechnical engineering: proceedings of the 2nd international symposium on Frost geotechnical engineering, Rotterdam: Balkema Publishers, A.A. / Taylor & Francis The Netherlands , 1993, p. 69-77Conference paper (Refereed)
  • 33.
    Viklander, Peter
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Knutsson, Sven
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Permeability changes in a fine-grained till du to cycles of freezing and thawing1997In: 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, p. 193-202Conference paper (Refereed)
  • 34.
    Viklander, Peter
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Knutsson, Sven
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Uppfrysning av block och stenar i vägar1999In: Bygg & Teknik, ISSN 0281-658X, Vol. 92, no 1, p. 39-41Article in journal (Other (popular science, discussion, etc.))
  • 35.
    Viklander, Peter
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Knutsson, Sven
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Magnusson, O.
    Luleå tekniska universitet.
    Laboratory compaction using an enlarged fall-weight apparatus1994In: 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, p. 425-428Conference paper (Refereed)
  • 36.
    Westerberg, Bo
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Viklander, Peter
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Ballastrening och bankettrensning på Malmbanan: en fält- och laboratoriestudie2001Report (Other academic)
    Abstract [sv]

    Syftet med studien var dels att bestämma tekniska egenskaper(kornfördelning, densitet, vattenkvot, infiltrationskapacitet, permeabilitet, kapillaritet) hos ballast och bankettens överskottsmassor genom fältförsök och genom laboratorieförsök och dels att baserat på bestämningen av de tekniska egenskaperna hos ballast och bankettens överskottsmassor undersöka behovet av och nyttan med ballastrening och bankettrensning. I studien har förhållandena i fyra sektioner längs Malmbanan, två på vardera sträckan Ljuså-Gransjö och Nattavaara-Kilvo, undersökts genom fältförsök och laboratorieförsök. Av de slutsatser som dragits i studien kan följande nämnas: Det nuvarande kriteriet (dvs när andelen partiklar, d<31.5 mm, överstiger 40 viktsprocent) för när ballastrening skall utföras bör ifrågasättas. Även andra faktorer (kriterier) än andelen partiklar mindre än 31.5 mm bör tas i beaktande för att avgöra när behov av rening finns. Sådana faktorer skulle kunna vara infiltrationskapacitet, porfyllnadsgrad (volymandelen finkornigt material i porutrymmet mellan makadamstenarna), tjällyftningsbenägenhet, dynamiska egenskaper, underballastens beskaffenhet, etc. Flera eller andra siktgränser (än 31.5 mm) och krav på maximal tillåten andel skulle kunna införas. Dessa gränser skall då baseras på olika egenskaper hos ballasten som kan förändras på ett negativt sätt vid en för hög halt av finkornigt material. Baserat på de faktorer som undersökts i denna studie kan konstateras att ballastrening var nödvändig att utföra för att skapa tillräcklig tjocklek på makadamballast och för att rena den nedre delen av ballasten men troligen inte nödvändig med tanke på dräneringsförmåga och tjälfarlighet. Baserat på de faktorer som undersökts i denna studie kan konstateras att bankettrensning var nödvändig att utföra för att ta bort stora mängder onyttiga överskottsmassor, vilket bl a medför att stabiliteten för banvallen ökar, men troligen inte nödvändigt med tanke på dräneringsförmåga och tjälfarlighet.

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