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Bernander, Stig
Publications (10 of 58) Show all publications
Elfgren, L. & Bernander, S. (2018). Response to and Comments on “Geotechnical Peer Review of Dr. S. Bernander’s Reports and Analysis of the North Spur”. Luleå: Luleå tekniska universitet
Open this publication in new window or tab >>Response to and Comments on “Geotechnical Peer Review of Dr. S. Bernander’s Reports and Analysis of the North Spur”
2018 (English)Report (Other academic)
Abstract [en]

The concerns regarding the stability of the North Spur can be summarized in three points:

(1) None of the most critical inclined failure surfaces have been studied by Muskrat Falls Corporation. These failure surfaces may be initiated on the upstream side of the dam containment. Here the effects of the deformations, caused by the pressure of the rising water level, have to be resisted by the metastable soil layers in the North Spur. A local failure may occur progressing downwards towards the downstream side of the Spur. A catastrophic dam breach would follow. The GPRP further categorically overlooks the fact that horizontal failure planes cannot possibly represent the highest risk of instability irrespective of whether the analysis is based on the Limit Equilibrium Mode (LEM) or on the Progressive Failure Mode.

(2) The stress/strain deformation properties of the porous soils in the North Spur have not been made available. Only strength properties, related to fully drained conditions, have been given. How stresses relate to simultaneous deformations under undrained (or partially undrained) conditions have not been defined in any way. Such relationships are crucially essential for any up-to-date analysis of slope stability.

(3) A high risk of North Spur instability has been found related to impoundment.  A series of investigatory calculations have been made, based on deformation properties from similar landslides and on a wide variety of assumed input data for possible critical failure surfaces. The results of these analyses indicated a safety factor far below 1.

The peer review does not address the above three points. It gives a good view of the general conditions but also contains misconceptions, erroneous considerations and refutable comments indicating that the earlier reports by Bernander have not been fully understood by the panel members.

As no up-to-date analysis of the stability of the North Spur has been provided, our conclusion is that an independent group of experts, appointed by government, should be entrusted with this important task.

Place, publisher, year, edition, pages
Luleå: Luleå tekniska universitet, 2018. p. 29
Series
Technical report / Luleå University of Technology, ISSN 1402-1536
Keywords
Dam Bank Stability, Forward Progressive Landslide, Long Natural Slopes, Strain-softening Soils
National Category
Geotechnical Engineering Infrastructure Engineering
Research subject
Structural Engineering; Soil Mechanics
Identifiers
urn:nbn:se:ltu:diva-70130 (URN)978-91-7790-181-5 (ISBN)
Available from: 2018-07-19 Created: 2018-07-19 Last updated: 2018-11-15Bibliographically approved
Bernander, S., Dury, R., Laue, J., Knutsson, S. & Elfgren, L. (2017). Progressive Landslide Analysis in Canadian Glacial Silty Clay in Churchill River. In: Vikas Thakur, Jean-Sébastien L’Heureux, Ariane Locat (Ed.), : . Paper presented at 2nd International Workshop on Landslides in Sensitive Clays, IWLSC 2017, Trondheim, June 12-14, 2017 (pp. 1).
Open this publication in new window or tab >>Progressive Landslide Analysis in Canadian Glacial Silty Clay in Churchill River
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2017 (English)In: / [ed] Vikas Thakur, Jean-Sébastien L’Heureux, Ariane Locat, 2017, p. 1-Conference paper, Poster (with or without abstract) (Other academic)
Abstract [en]

The poster presents the risks for a progressive landslide in a natural dam. The stability will be critical when the water level is raised after the building of a hydro power plant, Bernander (2016), Dury (2017). The analysis is based on a finite difference method developed by Stig Bernander (2011), Bernander et al.(2016)

 

The following issues will be discussed:  

- Material properties

- Risk for liquefaction

- Three possible failure surfaces: one horizontal, one inclined and one curved

- Failure riska for different material propeties

- The need to check the real properties of the soil

Keywords
Progressive Landslide Analysis, Glacial Silty Clay, Failure risk
National Category
Geotechnical Engineering Infrastructure Engineering
Research subject
Soil Mechanics; Structural Engineering
Identifiers
urn:nbn:se:ltu:diva-63860 (URN)
Conference
2nd International Workshop on Landslides in Sensitive Clays, IWLSC 2017, Trondheim, June 12-14, 2017
Available from: 2017-06-09 Created: 2017-06-09 Last updated: 2019-04-03Bibliographically approved
Dury, R., Bernander, S., Kullingsjö, A., Laue, J., Knutsson, S., Pusch, R. & Elfgren, L. (2017). Progressive Landslide Analysis with Bernander Finite Difference Method. In: Vikas Thakur, Jean-Sébastien L’Heureux, Ariane Locat (Ed.), : . Paper presented at 2nd International Workshop on Landslides in Sensitive Clays, IWLSC, Trondheim, 12-14 June 2017 (pp. 1).
Open this publication in new window or tab >>Progressive Landslide Analysis with Bernander Finite Difference Method
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2017 (English)In: / [ed] Vikas Thakur, Jean-Sébastien L’Heureux, Ariane Locat, 2017, p. 1-Conference paper, Poster (with or without abstract) (Other academic)
Abstract [en]

The poster presents a new Spreadsheet developed by Robin Dury (2017) to simplify the use of the Finite Difference Method developed by Stig Bernander et al (2011, 2016).

It includes:

- Material Properties

- Finite Difference Method

- Progressive failure process with five phses

- Discussion

- References

Keywords
Progressive Landslide Analysis, Finite Difference Method, Failure Process
National Category
Geotechnical Engineering Infrastructure Engineering
Research subject
Soil Mechanics; Structural Engineering
Identifiers
urn:nbn:se:ltu:diva-63858 (URN)
Conference
2nd International Workshop on Landslides in Sensitive Clays, IWLSC, Trondheim, 12-14 June 2017
Available from: 2017-06-09 Created: 2017-06-09 Last updated: 2018-06-26Bibliographically approved
Bernander, S. & Elfgren, L. (2017). Riverbank stability in loose layered silty clays: Comments on the North Spur Dam at Muskrat Falls in Churchill River, Labrador, Newfoundland. Luleå: Luleå tekniska universitet
Open this publication in new window or tab >>Riverbank stability in loose layered silty clays: Comments on the North Spur Dam at Muskrat Falls in Churchill River, Labrador, Newfoundland
2017 (English)Report (Refereed)
Abstract [en]

The differences are outlined in landslide analysis between the classic limit equilibrium method with assumed plastic properties of the soil and a progressive analysis applying softening material properties.

The risk for failure is studied in the dam at the North Spur riverbank ridge at Muskrat Falls in Churchill River in Labrador, Newfoundland, Canada. A sloping failure surface is much more critical than the horizontal surfaces which have hitherto been studied. Results from new analyses have now been obtained applying softening material properties probable for the ridge. The results indicate safety factors lower than 0.5, i.e. there is a high risk that the ridge will fail if the water level is raised to the proposed level.

Three reports are appended where Stig Bernander argues in detail for the need for a proper progressive failure analysis based on measured material properties. He also proposes how such properties may be obtained and gives an example of a way to stabilize the ridge if the soil properties show a softening behaviour. Finally examples of progressive failure analyses are included using probable material properties.

Place, publisher, year, edition, pages
Luleå: Luleå tekniska universitet, 2017. p. 144
Series
Technical report / Luleå University of Technology, ISSN 1402-1536
Keywords
Landslide, Riverbank stability, Progressive failure
National Category
Construction Management Infrastructure Engineering
Research subject
Structural Engineering
Identifiers
urn:nbn:se:ltu:diva-64723 (URN)978-91-7583-928-8 (ISBN)
Available from: 2017-07-02 Created: 2017-07-02 Last updated: 2017-11-24Bibliographically approved
Bernander, S., Kullingsjö, A., Gylland, A. K., Bengtsson, P.-E., Pusch, R., Knutsson, S., . . . Elfgren, L. (2016). Downhill Progressive Landslides in Long Natural Slopes: Triggering Agents and Landslide Phases modeled with a Finite Difference Method (ed.). Canadian geotechnical journal (Print), 53(10), 1565-1582
Open this publication in new window or tab >>Downhill Progressive Landslides in Long Natural Slopes: Triggering Agents and Landslide Phases modeled with a Finite Difference Method
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2016 (English)In: Canadian geotechnical journal (Print), ISSN 0008-3674, E-ISSN 1208-6010, Vol. 53, no 10, p. 1565-1582Article in journal (Refereed) Published
Abstract [en]

A large landslide in Tuve (Gothenburg, Sweden 1977) initiated the development of a model for slope stability analysis taking the deformation-softening of soft sensitive clays into consideration. The model studies triggering agents and five phases in progressive slope failure are identified: (1) in-situ, (2) disturbance, (3) unstable ‘dynamic’, (4) transitory (or permanent) equilibrium, and (5) ‘global’ failure. The clay resistance in these phases may differ widely; mostly due to different rates of loading. Two time dependent failure criteria are defined: (i) the triggering load condition in the disturbance Phase (2), and (ii) the transitory equilibrium in Phase (4), indicating whether minor downhill displacements or a veritable landslide catastrophe will occur. The analysis explains why downhill landslides tend to spread over vast areas of almost horizontal ground further down-slope. The model has been applied to landslides in Scandinavia and Canada. Three case studies are briefly discussed. The model is a finite difference approach, where local downhill deformations caused by normal forces is maintained compatible with deviatory shear deformations above the potential (or the established) failure surface. Software and an easy-to-use spreadsheet are introduced as well as recent developments. See also Video Abstract.

Keywords
Civil engineering and architecture - Geoengineering and mining engineering, Progressiva skred, Defoemationsmjuknande material, Samhällsbyggnadsteknik och arkitektur - Geoteknik och gruvteknik
National Category
Geotechnical Engineering Infrastructure Engineering
Research subject
Soil Mechanics; Structural Engineering; Attractive built environment (AERI)
Identifiers
urn:nbn:se:ltu:diva-8899 (URN)10.1139/cgj-2015-0651 (DOI)000385647600001 ()2-s2.0-84989869469 (Scopus ID)7728f175-24d8-44ef-9bc4-cedb0060ee63 (Local ID)7728f175-24d8-44ef-9bc4-cedb0060ee63 (Archive number)7728f175-24d8-44ef-9bc4-cedb0060ee63 (OAI)
Note

Validerad; 2016; Nivå 2; 2016-11-02 (andbra)

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Gylland, A. S., Sayd, M. S., Jostad, H. P. & Bernander, S. (2012). Soil property sensitivity in progressive failure of slopes (ed.). International Review of Civil Engineering (IRECE), 3(4)
Open this publication in new window or tab >>Soil property sensitivity in progressive failure of slopes
2012 (English)In: International Review of Civil Engineering (IRECE), ISSN 2036-9913, Vol. 3, no 4Article in journal (Refereed) Published
Abstract [en]

The presence of sensitive clay pose a challenge when performing slope stability assessments. Because of the strain softening behavior, the validity of conventional calculation methods based on the principle of limit equilibrium (LE) are not fully valid. This paper studies downward progressive failure in long natural slopes with an aim of identifying the governing parameters and the validity range of LE methods. A FEM approach which accounts for the non-linear stress-strain curve of the material, including the post peak softening behavior, is used. Sensitivity of the analyses to variations of key parameters like in-situ shear stress at the failure plane, brittleness, stiffness of the soil mass, and geometry are investigated in terms of critical load for initiating the slide and the corresponding critical length. The results show that the capacity of the slope in terms of external actions is reduced the steeper the slope is, the more strain softening behavior the material display and the lower stiffness the overlying soil has. The initial shear stress level is identified as a highly sensitive parameter. Further, by studying variations in the critical length it is indicated that the validity of classical LE methods is limited for steep slopes in soft and very sensitive clay

Keywords
Civil engineering and architecture - Building engineering, Civil engineering and architecture - Geoengineering and mining engineering, Samhällsbyggnadsteknik och arkitektur - Byggnadsteknik, Samhällsbyggnadsteknik och arkitektur - Geoteknik och gruvteknik
National Category
Infrastructure Engineering
Research subject
Structural Engineering
Identifiers
urn:nbn:se:ltu:diva-2944 (URN)0b037057-28ea-4e88-b55d-68a3d8d0a24a (Local ID)0b037057-28ea-4e88-b55d-68a3d8d0a24a (Archive number)0b037057-28ea-4e88-b55d-68a3d8d0a24a (OAI)
Note

Godkänd; 2012; 20120731 (stiber)

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2017-11-24Bibliographically approved
Locat, A., Leroueil, S., Bernander, S., Demers, D., Jostad, H. P. & Quehb, L. (2011). Progressive failures in eastern Canadian and Scandinavian sensitive clays (ed.). Paper presented at . Canadian geotechnical journal (Print), 48(11), 1696-1712
Open this publication in new window or tab >>Progressive failures in eastern Canadian and Scandinavian sensitive clays
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2011 (English)In: Canadian geotechnical journal (Print), ISSN 0008-3674, E-ISSN 1208-6010, Vol. 48, no 11, p. 1696-1712Article in journal (Refereed) Published
Abstract [en]

Observations from past events are used to show that the concept of progressive failure may explain translational progressive landslides and spreads — large landslides occurring in sensitive clays. During progressive failure, the strain-softening behaviour of the soil causes unstable forces to propagate a failure surface further in the slope. Translational progressive landslides generally take place in long, gently inclined slopes. Instability in a steeper upslope area is followed by redistribution of stress, which increases earth pressure further downslope. Passive failure may therefore occur in less-inclined ground, heaving the soil. Spreads are usually trigged by erosion of a deposit having a higher angle near the toe. Instability starts near the toe of the slope and propagates into the deposit, reducing earth pressure. This may lead to the formation of an active failure with dislocation of the deposit into horsts and grabens. The failure mechanism of both types of landslides is controlled by the stresses in the slope and the stress–strain behaviour of the soil. The mechanism presented explains the sensitivity of a slope to minor disturbances and the resulting high retrogressions observed for such landslides in Scandinavia and eastern Canada.

Keywords
Civil engineering and architecture - Building engineering, Civil engineering and architecture - Geoengineering and mining engineering, Samhällsbyggnadsteknik och arkitektur - Byggnadsteknik, Samhällsbyggnadsteknik och arkitektur - Geoteknik och gruvteknik
National Category
Infrastructure Engineering
Research subject
Structural Engineering
Identifiers
urn:nbn:se:ltu:diva-15006 (URN)10.1139/t11-059 (DOI)000298208200009 ()2-s2.0-80455143371 (Scopus ID)e76d5802-8fcc-42b4-82ec-798b4afc3a68 (Local ID)e76d5802-8fcc-42b4-82ec-798b4afc3a68 (Archive number)e76d5802-8fcc-42b4-82ec-798b4afc3a68 (OAI)
Note
Validerad; 2011; 20111101 (stiber)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Bernander, S. (2011). Progressive landslides in long natural slopes: Formation, potential extension and configuration of finished slides in strain-softening soils (ed.). (Doctoral dissertation). Paper presented at . Luleå: Luleå tekniska universitet
Open this publication in new window or tab >>Progressive landslides in long natural slopes: Formation, potential extension and configuration of finished slides in strain-softening soils
2011 (English)Doctoral thesis, comprehensive summary (Other academic)
Alternative title[sv]
Progressiva skred i långsträckta naturliga slänter : Orsaker, förlopp och utbredning hos skred i deformationsmjuknande jordar
Abstract [en]

After the large landslide in Tuve (Gothenburg, 1977), the author began developing a finite difference model for slope stability analysis taking the deformation-softening of soft sensitive clays into consideration. In the model, the mean down-slope deformation in each element caused by normal forces is maintained compatible with the deformation generated by shear stresses. He developed software for the model and presented it at international soil mechanics conferences during the 1980-ies. In 2000 he summarized his findings in a Licentiate thesis. An easy-to-use spread-sheet has also been developed. In this thesis the author conveys his experiences of slide modeling focusing on the nature of triggering agents and the different phases that a slope may undergo before its stability becomes truly critical.

Place, publisher, year, edition, pages
Luleå: Luleå tekniska universitet, 2011. p. 240
Series
Doctoral thesis / Luleå University of Technology 1 jan 1997 → …, ISSN 1402-1544
Keywords
Civil engineering and architecture - Building engineering, Samhällsbyggnadsteknik och arkitektur - Byggnadsteknik
National Category
Infrastructure Engineering Geotechnical Engineering
Research subject
Structural Engineering; Soil Mechanics
Identifiers
urn:nbn:se:ltu:diva-17872 (URN)5a493016-91bb-48e6-a087-1fc14a212bf4 (Local ID)978-91-7439-283-8 (ISBN)5a493016-91bb-48e6-a087-1fc14a212bf4 (Archive number)5a493016-91bb-48e6-a087-1fc14a212bf4 (OAI)
Note
Godkänd; 2011; 20110523 (stiber); Akademisk avhandling som med tillstånd av Dekanus för Tekniska fakulteten vid Luleå tekniska universitet för avläggande av teknologie doktorsexamen kommer att offentligt försvaras: Tisdagen den 16 augusti 2011, kl 10.00 i Sal F1031, Luleå tekniska universiteet Opponent: Professor Steinar Nordal, Institutt for Bygg, anlegg og transport, NTNU, Trondheim, NorgeAvailable from: 2016-09-29 Created: 2016-09-29 Last updated: 2017-11-24Bibliographically approved
Gylland, A. S., Sayd, M., Jostad, H.-P. & Bernander, S. (2010). Investigation of soil property sensitivity in progressive failure (ed.). In: (Ed.), Thomas Bentz; Steinar Nordahl (Ed.), Numerical Methods in Geotechnical Engineering: NUMGE 2010. Paper presented at European Conference on Numerical Methods in Geotechnical Engineering : 02/06/2010 - 04/06/2010 (pp. 515-520). Bosa Roca: CRC Press
Open this publication in new window or tab >>Investigation of soil property sensitivity in progressive failure
2010 (English)In: Numerical Methods in Geotechnical Engineering: NUMGE 2010 / [ed] Thomas Bentz; Steinar Nordahl, Bosa Roca: CRC Press, 2010, p. 515-520Conference paper, Published paper (Other academic)
Place, publisher, year, edition, pages
Bosa Roca: CRC Press, 2010
National Category
Geotechnical Engineering
Research subject
Soil Mechanics
Identifiers
urn:nbn:se:ltu:diva-35741 (URN)2-s2.0-79954577711 (Scopus ID)a663c4da-f997-4cc0-97fc-a06ef7fa61f0 (Local ID)9780415592390 (ISBN)a663c4da-f997-4cc0-97fc-a06ef7fa61f0 (Archive number)a663c4da-f997-4cc0-97fc-a06ef7fa61f0 (OAI)
Conference
European Conference on Numerical Methods in Geotechnical Engineering : 02/06/2010 - 04/06/2010
Note

Godkänd; 2010; 20110904 (stiber)

Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2018-03-20Bibliographically approved
Bernander, S. (2008). Down-hill progressive landslides in soft clays: Triggering disturbance agents, Slide Propagation over horizontal or gently sloping ground, Sensitivity related to geometry (ed.). Paper presented at . Luleå: Luleå tekniska universitet
Open this publication in new window or tab >>Down-hill progressive landslides in soft clays: Triggering disturbance agents, Slide Propagation over horizontal or gently sloping ground, Sensitivity related to geometry
2008 (English)Report (Other academic)
Abstract [en]

A numerical model is presented and discussed for down-hill progressive landslides in soft clays. A simple-to-use spread sheet is given and used in order to illustrate the influence of the sensitivity of the clay and the geometry of the ground. The model is also used to discuss the agents and the mechanisms that formed the large landslide in Surte at the Göta River in 1950.

Place, publisher, year, edition, pages
Luleå: Luleå tekniska universitet, 2008. p. 120
Series
Research report / Luleå University of Technology, ISSN 1402-1528 ; 2008:11
Keywords
Civil engineering and architecture - Geoengineering and mining engineering, Samhällsbyggnadsteknik och arkitektur - Geoteknik och gruvteknik
National Category
Geotechnical Engineering
Research subject
Soil Mechanics
Identifiers
urn:nbn:se:ltu:diva-22213 (URN)1fa0cc20-962d-11de-8da0-000ea68e967b (Local ID)1fa0cc20-962d-11de-8da0-000ea68e967b (Archive number)1fa0cc20-962d-11de-8da0-000ea68e967b (OAI)
Note
Godkänd; 2008; 20090831 (ysko)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2017-11-24Bibliographically approved
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