Endre søk
RefereraExporteraLink to record
Permanent link

Direct link
Referera
Referensformat
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Shear Strength of Unfilled and Rough Rock Joints in Sliding Stability Analyses of Concrete Dams
KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Jord- och bergmekanik.ORCID-id: 0000-0002-8152-6092
2009 (engelsk)Doktoravhandling, monografi (Annet vitenskapelig)
Abstract [en]

The horizontal water load combined with uplift forces implies that concrete damsare sensitive for sliding. At the same time, the safety of concrete dams againstsliding in the rock foundation is associated with large uncertainties. One of themain uncertainties regards the shear strength of rock joints.

Several failure criteria exist to express the shear strength for unfilled and roughrock joints. However, these criteria do not in general consider a possible scaleeffect which means that the shear strength could be lower at larger scales. Somesuggestions exist for how a possible scale effect could be considered, but theseare mainly based on empiric grounds. This means that there exists a need of amore detailed and conceptual understanding on the scale effect of rock joints.

In an attempt to increase the understanding on the scale effect of unfilled andrough rock joints, a conceptual model was derived. The model is based on theassumptions that contact points occur at the steepest asperities facing the sheardirection and that their total area could be expressed with adhesion theory. Fractaltheory is used in order to idealize the surface roughness by superposition ofasperities at different scales. Based on changes in the size and number of contactpoints, the conceptual model suggests that the scale effect does not occur for alltypes of rock joints. Perfectly mated joints are suggested to not exhibit any scaleeffect while a considerable scale effect could be expected for unmated joints.

The practical implications from this, for foundations with unfilled joints, is thatunmated joints with large aperture are most critical for the sliding stability ofconcrete dams, since these joints probably are the ones with longest persistenceand lowest shear strength.

In order to study the scale effect of rock joints further, eighteen shear tests atdifferent scales were performed. All of the samples were taken from the rockfoundation at Långbjörn hydropower station. Possible scale effects could beobserved, but no firm conclusions could be made, mainly due to different surfacecharacteristics of the tested joints. Three of the samples were also used toinvestigate the accuracy of the conceptual model. This investigation revealed thatit may be necessary to distinguish between weathered and unweathered joints,since the distribution of contact points appears to become more randomlydistributed for a weathered joint which in turn results in lower friction angles.

In Sweden, dam safety is governed by the Swedish power company’s guidelinesfor dam safety, RIDAS. When the Swedish guidelines were compared withguidelines and regulations in other countries, it was realized that there exists aneed for a more balanced evaluation of the sliding stability for concrete damsfounded on rock in Sweden. In a first step of development, it can be based onsafety factors and an increased use of investigations. However, in a second step, anatural way of the development of RIDAS would be in a direction towardsreliability based methods.

sted, utgiver, år, opplag, sider
Stockholm: KTH , 2009. , s. x, 162, xxvi
Serie
TRITA-JOB. PHD ; 1013
HSV kategori
Identifikatorer
URN: urn:nbn:se:kth:diva-10450OAI: oai:DiVA.org:kth-10450DiVA, id: diva2:217569
Disputas
2009-05-15, D2, KTH, Lindstedtsvägen 5, Stockholm, 10:00 (engelsk)
Opponent
Veileder
Merknad

QC20100709

Tilgjengelig fra: 2009-05-14 Laget: 2009-05-14 Sist oppdatert: 2017-08-15bibliografisk kontrollert

Open Access i DiVA

fulltekst(9075 kB)4714 nedlastinger
Filinformasjon
Fil FULLTEXT01.pdfFilstørrelse 9075 kBChecksum SHA-512
1b1a80ea046416f4a75ad3218b963c83d337d2b9ee820636b39c35ea6a12d5f7721a85b5c9b4a5219cb4383074e55326aec42e39104f423ffe6c8e7d5dcb88e6
Type fulltextMimetype application/pdf

Personposter BETA

Johansson, Fredrik

Søk i DiVA

Av forfatter/redaktør
Johansson, Fredrik
Av organisasjonen

Søk utenfor DiVA

GoogleGoogle Scholar
Totalt: 4714 nedlastinger
Antall nedlastinger er summen av alle nedlastinger av alle fulltekster. Det kan for eksempel være tidligere versjoner som er ikke lenger tilgjengelige

urn-nbn

Altmetric

urn-nbn
Totalt: 1318 treff
RefereraExporteraLink to record
Permanent link

Direct link
Referera
Referensformat
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf