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Optimizing geotechnical site-investigations
KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.ORCID iD: 0000-0001-5243-4650
KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.ORCID iD: 0000-0001-9615-4861
Tyréns AB.
2017 (English)In: Proceedings of the 19th International Conference on Soil Mechanics and Geotechnical Engineering, Seoul 2017, 2017, p. 639-642Conference paper, Published paper (Refereed)
Abstract [en]

One major question to deal with in the process of updating the current version of Eurocode 7 is how to convert thequality of a performed site-investigation into a measurable context. This should, in turn, affect the safety factor applied to the soil-strength properties in a limit state. This paper presents a study in which the total uncertainty from the evaluation of undrained shearstrength in clay is assessed from single and multiple site-investigation methods with regard to both random and systematicuncertainties. A Bayesian procedure is used to convert potential reduction of random and systematic uncertainties into a measurablecontext in relation to: (1) the type of site-investigation method, (2) the combination of methods, and (3) the number of measurementsperformed.

Abstract [fr]

L’une des questions majeures qui se posent lors du processus de mise à jour de la version actuelle de l’Eurocode 7est la suivante : comment convertir la qualité d’une investigation de site en une quantité mesurable ? Cela devrait alors affecterle niveau de sécurité appliqué aux propriétés de résistance du sol dans un état limite. Cet article présente une étude au cours de laquelle l’incertitude totale découlant de l’évaluation de la résistance au cisaillement de l’argile non évacuée est évaluée à partir de méthodes d’investigation de site uniques et multiples en relation avec des incertitudes aléatoires et systématiques. Une procédure bayésienne est utilisée pour convertir la réduction potentielle des incertitudes aléatoires et systématiques en une incertitude mesurable en rapport avec : (1) le type de méthode d’investigation de site, (2) la combinaison des méthodes, (3) le nombre de mesures effectuées.

Place, publisher, year, edition, pages
2017. p. 639-642
National Category
Geotechnical Engineering
Identifiers
URN: urn:nbn:se:kth:diva-221082Scopus ID: 2-s2.0-85040043034OAI: oai:DiVA.org:kth-221082DiVA, id: diva2:1173340
Conference
19th International Conference on Soil Mechanics and Geotechnical Engineering, 17 to 21 September 2017, Seoul 2017
Funder
Swedish Research Council Formas
Note

QC 20180115

Available from: 2018-01-12 Created: 2018-01-12 Last updated: 2019-08-20Bibliographically approved
In thesis
1. Managing uncertainties in geotechnical parameters: From the perspective of Eurocode 7
Open this publication in new window or tab >>Managing uncertainties in geotechnical parameters: From the perspective of Eurocode 7
2019 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Geotechnical engineering is strongly associated with large uncertainties. Geotechnical site investigations are made only at discrete points and most of a soil volume is never tested. A major issue is therefore how to cost effectively reduce geotechnical uncertainties with respect to structural performance. Managing the geotechnical uncertainties is thus an important aspect of the design process. Guidance on this subject is given in the European design code for geotechnical design, Eurocode 7 (EN 1997), which advocates the use of the partial-factor method, with the added possibility to use the observational method if the uncertainties are large and difficult to assess.This thesis aims to highlight, develop and improve methods to assess the quality and value of geotechnical site investigations through reliability-based design. The thesis also discusses the limitations of the deterministic partial-factor method, according to its EN 1997 definition, and how to better harmonise this design methodology with the risk-based approach of reliability-based design. The main research contributions are: (1) a presented case study showing the importance of and potential gains with a robust framework for statistical evaluation of geotechnical parameters, (2) the discussion on the limitations of the partial-factor method in EN 1997, and (3) the discussion on how to harmonise the EN 1997 definition of the partial-factor method with the risk-based approach of reliability-based design.

Abstract [sv]

Geoteknik förknippas med ett stort antal osäkerheter. Geotekniska undersökningar utförs i diskreta punkter och den absolut största delen av en jordvolym testas aldrig. En viktig fråga inom geotekniken är därför hur man kan minimera osäkerheterna i relation till kostnaderna för undersökningarna och konstruktionens säkerhet. En annan fråga som uppstår när en konstruktion ska dimensioneras är hur osäkerheterna bör hanteras i dimensioneringsprocessen. För detta ges vägledning i de europeiska dimensioneringsprinciperna för geotekniska konstruktioner, Eurokod 7 (EN 1997), som förespråkar partialkoefficientmetoden. Om osäkerheterna är stora och svåra att uppskatta kan observationsmetoden användas som ett komplement. Syftet med denna avhandling är att belysa, utveckla och förbättra metoder för bygg- och anläggningsbranschen att uppskatta kvalité och värde av geotekniska undersökningar. Ett bayesianskt tillvägagångssätt (multivariabel analys) har använts för att utvärdera osäkerheterna relaterade till de geotekniska undersökningarna. Därtill presenterar avhandlingen en diskussion om begränsningarna i partialkoefficientmetoden, enligt definitionen i EN 1997, och hur denna metod kan utvecklas för att bättre harmonisera med sannolikhetsbaserad dimensionering. De huvudsakliga forskningsbidragen är: (1) den presenterade fallstudien som visar vikten, och den potentiella nyttan, av ett robust ramverk för statistisk utvärdering av geotekniska parametrar som grund för sannolikhetsbaserad dimensionering, (2) diskussionen om begränsningarna med partialkoefficientmetoden enligt definitionen i EN1997, och (3) diskussionen om hur partialkoefficientmetoden kan utvecklas för att bättre harmonisera med sannolikhetsbaserad dimensionering.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2019. p. 79
Series
TRITA-ABE-DLT ; 1924
Keywords
Eurocode 7, Characteristic value, Partial-factor method, Reliability-based design
National Category
Geotechnical Engineering
Research subject
Civil and Architectural Engineering
Identifiers
urn:nbn:se:kth:diva-256058 (URN)978-91-7873-249-4 (ISBN)
Public defence
2019-09-19, Kollegiesalen, Brinellvägen 8, Stockholm, 13:00 (English)
Opponent
Supervisors
Funder
Swedish Research Council FormasSwedish Transport Administration
Note

QC 20190822

Available from: 2019-08-22 Created: 2019-08-20 Last updated: 2019-08-22Bibliographically approved

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Prästings, AndersLarsson, Stefan

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