Change search
Link to record
Permanent link

Direct link
BETA
Publications (10 of 34) Show all publications
Silva, I., Viklander, P. & Laue, J. (2018). Effects of Void Ratio and Hydraulic Gradient on Permeability and Suffusion of Glacial Till Cores. In: Stéphane Bonelli, Cristina Jommi, Donatella Sterpi (Ed.), Internal Erosion in Earthdams, Dikes and Levees: Proceedings of EWG‐IE 26th Annual Meeting 2018. Paper presented at European Working Group on Internal Erosion, Milan, Italy, 10-13 September 2018 (pp. 98-109). Cham: Springer
Open this publication in new window or tab >>Effects of Void Ratio and Hydraulic Gradient on Permeability and Suffusion of Glacial Till Cores
2018 (English)In: 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, Published 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.

Place, publisher, year, edition, pages
Cham: Springer, 2018
Series
Lecture Notes in Civil Engineering
National Category
Geotechnical Engineering
Research subject
Soil Mechanics
Identifiers
urn:nbn:se:ltu:diva-70716 (URN)10.1007/978-3-319-99423-9_10 (DOI)978-3-319-99422-2 (ISBN)978-3-319-99423-9 (ISBN)
Conference
European Working Group on Internal Erosion, Milan, Italy, 10-13 September 2018
Available from: 2018-09-03 Created: 2018-09-03 Last updated: 2019-03-19Bibliographically approved
Knutsson, R., Viklander, P., Knutsson, S. & Laue, J. (2018). How to avoid permafrost while depositing tailings in cold climate. Cold Regions Science and Technology, 153, 86-96
Open this publication in new window or tab >>How to avoid permafrost while depositing tailings in cold climate
2018 (English)In: Cold Regions Science and Technology, ISSN 0165-232X, E-ISSN 1872-7441, Vol. 153, p. 86-96Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
Elsevier, 2018
National Category
Geotechnical Engineering
Research subject
Soil Mechanics
Identifiers
urn:nbn:se:ltu:diva-68963 (URN)10.1016/j.coldregions.2018.05.009 (DOI)000439349800010 ()2-s2.0-85047628128 (Scopus ID)
Note

Validerad;2018;Nivå 2;2018-06-04 (andbra)

Available from: 2018-05-29 Created: 2018-05-29 Last updated: 2018-08-09Bibliographically approved
Silva, I., Lindblom, J., Viklander, P. & Laue, J. (2017). Assessment of internal erosion in the glacial till core of a Swedish dam. In: : . Paper presented at 85th Annual Meeting of International Commission on Large Dams (ICOLD 2017), Prague, Czech Republic, July 3–7, 2017.
Open this publication in new window or tab >>Assessment of internal erosion in the glacial till core of a Swedish dam
2017 (English)Conference paper, Published 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.

Keywords
internal erosion, glacial till, suffusion, filter, core, dam, embankment dams, Swedish dam, sinkhole, RIDAS, Vattenfall 1958, dam safety, internal instability, erosion, silty sandy gravel, moraine, erosion interna, presas, presas de tierra, núcleo, filtro, grava arenosa limosa, internamente inestable
National Category
Geotechnical Engineering Other Civil Engineering
Research subject
Soil Mechanics
Identifiers
urn:nbn:se:ltu:diva-65289 (URN)
Conference
85th Annual Meeting of International Commission on Large Dams (ICOLD 2017), Prague, Czech Republic, July 3–7, 2017
Available from: 2017-08-23 Created: 2017-08-23 Last updated: 2019-03-19Bibliographically approved
Rönnqvist, H., Viklander, P. & Knutsson, S. (2017). Experimental Investigation of Suffusion in Dam Core Soils of Glacial Till (ed.). ASTM geotechnical testing journal, 40(3), 426-439
Open this publication in new window or tab >>Experimental Investigation of Suffusion in Dam Core Soils of Glacial Till
2017 (English)In: ASTM geotechnical testing journal, ISSN 0149-6115, E-ISSN 1945-7545, Vol. 40, no 3, p. 426-439Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
ASTM International, 2017
Keywords
embankment dams, internal erosion, internal stability, suffusion, filters, cores, glacial tills
National Category
Geotechnical Engineering
Research subject
Soil Mechanics
Identifiers
urn:nbn:se:ltu:diva-13071 (URN)10.1520/GTJ20150298 (DOI)000405477000003 ()2-s2.0-85051199710 (Scopus ID)c3afe618-d30e-433d-b94f-caa8707ae2dd (Local ID)c3afe618-d30e-433d-b94f-caa8707ae2dd (Archive number)c3afe618-d30e-433d-b94f-caa8707ae2dd (OAI)
Note

Validerad;2017;Nivå 2;2017-06-08 (rokbeg)

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-08-17Bibliographically approved
Rönnqvist, H. & Viklander, P. (2016). A unified-plot approach for the assessment of internal erosion in embankment dams (ed.). Paper presented at . International Journal of Geotechnical Engineering, 10(1), 66-80
Open this publication in new window or tab >>A unified-plot approach for the assessment of internal erosion in embankment dams
2016 (English)In: International Journal of Geotechnical Engineering, ISSN 1938-6362, E-ISSN 1939-7879, Vol. 10, no 1, p. 66-80Article in journal (Refereed) Published
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.

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. 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, analysis shows a correlation between deficiencies attributed to internal erosion with the potential for internal instability and the capacity of the filter for soil retention. From comparison to field experience, an approach to assess existing dams and internal erosion is proposed by combining these two attributes of filter gradation in a unified plot. The finding implies that a unified plot may serve as a preliminary screening tool in engineering practice.

National Category
Geotechnical Engineering
Research subject
Soil Mechanics
Identifiers
urn:nbn:se:ltu:diva-6441 (URN)10.1179/1939787915Y.0000000002 (DOI)000371793100009 ()2-s2.0-84961806553 (Scopus ID)4aa8c9e2-3488-4402-98b3-b332bfec1fd2 (Local ID)4aa8c9e2-3488-4402-98b3-b332bfec1fd2 (Archive number)4aa8c9e2-3488-4402-98b3-b332bfec1fd2 (OAI)
Note
Validerad; 2016; Nivå 2; 20141121 (hayrof)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Rönnqvist, H. & Viklander, P. (2016). Effects of suffusion in embankment dam filters (ed.). Dams and Reservoirs, 26(3), 118-125
Open this publication in new window or tab >>Effects of suffusion in embankment dam filters
2016 (English)In: Dams and Reservoirs, ISSN 1368-1494, E-ISSN 1756-8404, Vol. 26, no 3, p. 118-125Article in journal (Refereed) Published
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.

National Category
Geotechnical Engineering
Research subject
Soil Mechanics
Identifiers
urn:nbn:se:ltu:diva-11378 (URN)10.1680/jdare.16.00023 (DOI)2-s2.0-84995676408 (Scopus ID)a548a6b1-b293-4f6b-bd34-a587dc1d0fd5 (Local ID)a548a6b1-b293-4f6b-bd34-a587dc1d0fd5 (Archive number)a548a6b1-b293-4f6b-bd34-a587dc1d0fd5 (OAI)
Note

Validerad; 2016; Nivå 1; 2016-11-16 (rokbeg)

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-06-26Bibliographically approved
Moghadas, S., Perttu, A.-M., Viklander, P., Marsalek, J. & Viklander, M. (2016). Laboratory study of infiltration into two frozen engineered (sandy) soils recommended for bioretention (ed.). Paper presented at . Hydrological Processes, 30(8), 1251-1264
Open this publication in new window or tab >>Laboratory study of infiltration into two frozen engineered (sandy) soils recommended for bioretention
Show others...
2016 (English)In: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 30, no 8, p. 1251-1264Article in journal (Refereed) Published
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.

National Category
Water Engineering Geotechnical Engineering
Research subject
Urban Water Engineering; Soil Mechanics
Identifiers
urn:nbn:se:ltu:diva-14505 (URN)10.1002/hyp.10711 (DOI)000373959500007 ()2-s2.0-84947996817 (Scopus ID)ddfe0621-5037-4a4b-a069-375d4859d71b (Local ID)ddfe0621-5037-4a4b-a069-375d4859d71b (Archive number)ddfe0621-5037-4a4b-a069-375d4859d71b (OAI)
Note
Validerad; 2016; Nivå 2; 20151110 (shamog)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Knutsson, R., Viklander, P. & Knutsson, S. (2016). Stability considerations for thickened tailings due to freezing and thawing. In: Sergio Barrea & Richard Jewell (Ed.), Paste 2016: Proceedings of the 19th International Seminar on Paste and Thickened Tailings. Paper presented at 19th International Seminar on Paste and Thickened Tailings, Santiago, Chile, July 5-8 2016 (pp. 567-577). Santiago: GECAMIN
Open this publication in new window or tab >>Stability considerations for thickened tailings due to freezing and thawing
2016 (English)In: 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, Published paper (Refereed)
Place, publisher, year, edition, pages
Santiago: GECAMIN, 2016
National Category
Geotechnical Engineering
Research subject
Soil Mechanics
Identifiers
urn:nbn:se:ltu:diva-61174 (URN)
Conference
19th International Seminar on Paste and Thickened Tailings, Santiago, Chile, July 5-8 2016
Available from: 2016-12-20 Created: 2016-12-20 Last updated: 2018-06-26Bibliographically approved
Rönnqvist, H. & Viklander, P. (2015). Applying empirical methods to assess the internal stability of embankment dam cores of glacial till (ed.). Geomaterials, 5, 1-18
Open this publication in new window or tab >>Applying empirical methods to assess the internal stability of embankment dam cores of glacial till
2015 (English)In: Geomaterials, ISSN 2161-7538, E-ISSN 2161-7546, Vol. 5, p. 1-18Article in journal (Refereed) Published
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.

National Category
Geotechnical Engineering
Research subject
Soil Mechanics
Identifiers
urn:nbn:se:ltu:diva-3681 (URN)10.4236/gm.2015.51001 (DOI)18024e50-578c-4f98-80c5-07386d392c86 (Local ID)18024e50-578c-4f98-80c5-07386d392c86 (Archive number)18024e50-578c-4f98-80c5-07386d392c86 (OAI)
Note

Godkänd; 2014; 20141028 (hayrof)

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-06-26Bibliographically approved
Rönnqvist, H., Fannin, J., Viklander, P. & Wang, L. (2015). Discussion: On the use of empirical methods for assessment of filters in embankment dams (ed.). Paper presented at . Geotechnique Letters, 5(July-September), 140-141
Open this publication in new window or tab >>Discussion: On the use of empirical methods for assessment of filters in embankment dams
2015 (English)In: Geotechnique Letters, E-ISSN 2045-2543, Vol. 5, no July-September, p. 140-141Article in journal, Editorial material (Refereed) Published
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.

National Category
Geotechnical Engineering
Research subject
Soil Mechanics
Identifiers
urn:nbn:se:ltu:diva-8900 (URN)10.1680/geolett.14.00114 (DOI)000359265700009 ()772b8863-9a79-4ceb-b7d7-2cccc9e2a3f5 (Local ID)772b8863-9a79-4ceb-b7d7-2cccc9e2a3f5 (Archive number)772b8863-9a79-4ceb-b7d7-2cccc9e2a3f5 (OAI)
Note
Godkänd; 2015; 20150313 (hayrof)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0001-8739-2219

Search in DiVA

Show all publications