Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
When is the observational method in geotechnical engineering favourable?
KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.ORCID iD: 0000-0001-5372-7519
KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.ORCID iD: 0000-0002-8152-6092
2017 (English)In: Structural Safety, ISSN 0167-4730, E-ISSN 1879-3355, Vol. 66, 17-26 p.Article in journal (Refereed) Published
Abstract [en]

The observational method in geotechnical engineering is an acceptable verification method for limit states in Eurocode 7, but the method is rarely used despite its potential savings. Some reasons may be its unclear safety definition and the lack of guidelines on how to establish whether the observational method is more favourable than conventional design. In this paper, we challenge these issues by introducing a reliability con­straint on the observational method and propose a probabilistic optimi­sation methodology that aids the decision-making engineer in choosing between the observational method and conventional design. The method­ology suggests an optimal design after comparing the expected utilities of the considered design options. The methodology is illustrated with a practical example, in which a geotechnical engineer evaluates whether the observational method may be favourable in the design of a rock pillar. We conclude that the methodology may prove to be a valuable tool for deci­sion-making engineers’ everyday work with managing risks in geotech­nical projects.

Place, publisher, year, edition, pages
2017. Vol. 66, 17-26 p.
Keyword [en]
Observational method, reliability-based design, decision analysis, Eurocode 7
National Category
Geotechnical Engineering
Research subject
Civil and Architectural Engineering
Identifiers
URN: urn:nbn:se:kth:diva-192821DOI: 10.1016/j.strusafe.2017.01.006Scopus ID: 2-s2.0-85011115079OAI: oai:DiVA.org:kth-192821DiVA: diva2:972217
Note

QC 20160923

Available from: 2016-09-20 Created: 2016-09-20 Last updated: 2017-05-23Bibliographically approved
In thesis
1. Toward a reliability framework for the observational method
Open this publication in new window or tab >>Toward a reliability framework for the observational method
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Constructing sustainable structures in rock that satisfy all predefined technical specifications requires rational and effective construction methods. When the geotechnical behaviour is hard to predict, the Euro­pean design code, Eurocode 7, suggests application of the observational method to verify that the performance is acceptable. The basic principle of the method is to accept predefined changes in the design during con­struction to comply with the actual ground conditions, if the current de­sign is found unsuitable. Even though this in theory should ensure an effective design solution, formal application of the observational method is rare.

Investigating the applicability of the observational method in rock en­gineering, the aim of this thesis is to identify, highlight, and solve the aspects of the method that limit its wider application. Furthermore, the thesis aims to improve the conceptual understanding of how design deci­sions should be made when large uncertainties are present.

The main research contribution is a probabilistic framework for the observational method. The suggested methodology allows comparison of the merits of the observational method with that of conventional design. Among other things, the thesis also discusses (1) the apparent contradiction between the preference for advanced probabilistic calculation methods and sound, qualitative engineering judgement, (2) how the establishment of limit states and alarm limits must be carefully considered to ensure structural safety, and (3) the applicability of the Eurocode defini­tion of the observational method and the implications of deviations from its principles.

Abstract [sv]

För att kunna konstruera en anläggning i berg, som uppfyller satta tek­niska krav, krävs det en rationell och effektiv konstruktionsmetod. När konstruktionens beteende är svårt att förutsäga, erbjuder den europeiska standarden Eurokod 7 den så kallade observationsmetoden. Denna metod tillåter i förväg förberedda förändringar i designen under konstruktions­tiden, om observationer av konstruktionens beteende indikerar att så behövs. På så vis anpassas konstruktionen till de faktiska förhållandena i marken. Trots att detta tillvägagångssätt i teorin ger en rationell design, används metoden sällan i enlighet med Eurokod 7.

Denna doktorsavhandling undersöker tillämpbarheten av observa-tionsmetoden när man bygger i och på berg. Målet är att belysa de aspekter som begränsar dess användning och i dessa fall föreslå förbätt­ringar som ökar tillämpbarheten. I ett vidare perspektiv syftar avhand­lingen även till att förbättra den konceptuella förståelsen för hur beslut bör fattas i designprocessen när det finns stora osäkerheter.

Avhandlingen visar hur observationsmetoden kan användas i ett san­nolikhetsbaserat ramverk. Metodiken ger användaren möjlighet att jäm­föra för- och nackdelarna med observationsmetoden och konventionell dimensionering. Avhandlingen diskuterar bland annat även (1) den skenbara motsatsen mellan användandet av sannolikhetsbaserade beräkningsmetoder för att lösa komplexa dimensioneringsfrågor och kvalitativa ingenjörsmässiga bedömningar, (2) hur larmgränser och brottgränstillstånd bör definieras för att ge tillräcklig säkerhetsmarginal, samt (3) hur Eurokod 7:s strikta definition av observationsmetoden påverkar dess användbarhet.

Place, publisher, year, edition, pages
Stockholm: Kungliga Tekniska högskolan, 2016
Series
TRITA-JOB PHD, ISSN 1650-9501 ; 1023
Keyword
Rock engineering, observational method, Eurocode 7, structural safety, reliability analysis, dam safety, Bergmekanik, observationsmetoden, Eurokod 7, sannolikhetsbaserad dimensionering, dammsäkerhet
National Category
Geotechnical Engineering
Research subject
Civil and Architectural Engineering
Identifiers
urn:nbn:se:kth:diva-192825 (URN)978-91-7729-128-2 (ISBN)
Public defence
2016-10-25, F3, Lindstedtsvägen 26, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

QC 20160926

Available from: 2016-09-26 Created: 2016-09-20 Last updated: 2016-09-26Bibliographically approved

Open Access in DiVA

fulltext(1726 kB)71 downloads
File information
File name FULLTEXT01.pdfFile size 1726 kBChecksum SHA-512
fd26e1096d81aaa913c7412523beb2a13582f24cd34badd855ac0b2fcc58f65bd6421a1862e136b210d7005c9f53d0e4d0b917eddf3652217f450031679cd983
Type fulltextMimetype application/pdf

Other links

Publisher's full textScopus

Authority records BETA

Spross, JohanJohansson, Fredrik

Search in DiVA

By author/editor
Spross, JohanJohansson, Fredrik
By organisation
Soil and Rock Mechanics
In the same journal
Structural Safety
Geotechnical Engineering

Search outside of DiVA

GoogleGoogle Scholar
Total: 71 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

doi
urn-nbn

Altmetric score

doi
urn-nbn
Total: 302 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf