Canadian Dam Association Bulletin - Summer 2017 - 13

ABSTRACT
The project is a 1100 MW generating station on the Peace River near Fort St. John, BC, Canada.
The project is underlain by dark grey moderately weak, flaky to fissile, silty shale, interbedded
with thin beds of siltstone, sandstone and shale. Thick glacial deposits were eroded as the ice
masses receded and the Peace River down-cut a valley resulting in substantial redistribution of
stresses in the river valley walls and an upward bulging of the valley floor and inward relaxation of the valley walls. Shear movement along thin weak bedding planes and local thrust faults
also developed. Near-vertical jointing, parallel to the valley walls, weak bedding planes and
cross-cutting discontinuities have been identified in both abutments. The original configuration
of the spillway headworks and intakes were concrete gravity structures founded on deep cuts in
the bedrock with weak bedding planes that daylight in the excavated slopes. A new layout was
developed where the horizontal water forces on the headworks structures were taken down an
inclined "buttress" to the bedrock below the river valley floor and by-passing the weak bedding
planes located in the valley walls. This resulted in the unique concept of the RCC Buttress supporting the headworks structures, powerhouse and spillway structures.

RÉSUMÉ
Ce projet hydroélectrique d'une puissance installée de 1100 MW se situe sur la Peace River, près
de Fort St John, CB, Canada. Le projet repose sur des schistes argileux gris foncé de résistance
modérément faible, de feuilletés à fissurés, avec stratifications de schiste silteux et de minces lits
de siltite, de grès et de schiste. Les épais dépôts glaciaires ont été érodés progressivement après
la fonte des glaciers par la Peace River ; celle-ci a taillé une vallée entraînant une redistribution
substantielle des contraintes sur les deux versants de la rivière, accompagnée d'un rebond du
lit de la rivière ainsi qu'une relaxation latérale des versants. Des mouvements de cisaillement le
long des plans de stratification minces et faibles ainsi que des failles de chevauchement locales
se sont également développés. Des joints quasi verticaux, parallèles aux versants de la vallée,
ainsi que de faibles plans de stratification et des discontinuités transversales ont été identifiés sur
les deux appuis. La configuration originale la structure de l'évacuateur de crues et des passages
hydrauliques était formée d'ouvrages poids en béton fondés sur des excavations profondes dans
le roc avec la stratification des faibles plans de déposition exposée sur les versants excavés. Une
nouvelle disposition des ouvrages a été développée où les forces hydrostatiques horizontales sur
la structure sont transférées vers le bas de la fondation par un « contrefort » fondé sur le rocher
en profondeur, bien en dessous du lit de la rivière, évitant ainsi les plans de glissement préférentiels présents au niveau des versants de la vallée. Un concept unique a été développé avec un
contrefort en BCR supportant la structure des ouvrages de tête, de la centrale hydroélectrique
et de l'évacuateur de crues.

Canadian Dam Association * Summer 2017

13



Table of Contents for the Digital Edition of Canadian Dam Association Bulletin - Summer 2017

Board of Directors
President's Message
Roller Compacted Concrete Buttress at the Site C Clean Energy Project
Hurricane Igor's Impact on Newfoundland Power's Small Hydro
CDA Conference Heads to Kelowna!
CDA Directors & Officers - Call for Nominations
2017 CDA Awards - Call for Nominations
CDA Developing New Ways to Distribute Guidelines
Notice of Annual General Meeting
Time to Renew Your Membership
Buyers' Guide and Trade List
Canadian Dam Association Bulletin - Summer 2017 - intro
Canadian Dam Association Bulletin - Summer 2017 - 1
Canadian Dam Association Bulletin - Summer 2017 - 2
Canadian Dam Association Bulletin - Summer 2017 - 3
Canadian Dam Association Bulletin - Summer 2017 - 4
Canadian Dam Association Bulletin - Summer 2017 - 5
Canadian Dam Association Bulletin - Summer 2017 - 6
Canadian Dam Association Bulletin - Summer 2017 - Board of Directors
Canadian Dam Association Bulletin - Summer 2017 - 8
Canadian Dam Association Bulletin - Summer 2017 - President's Message
Canadian Dam Association Bulletin - Summer 2017 - 10
Canadian Dam Association Bulletin - Summer 2017 - 11
Canadian Dam Association Bulletin - Summer 2017 - Roller Compacted Concrete Buttress at the Site C Clean Energy Project
Canadian Dam Association Bulletin - Summer 2017 - 13
Canadian Dam Association Bulletin - Summer 2017 - 14
Canadian Dam Association Bulletin - Summer 2017 - 15
Canadian Dam Association Bulletin - Summer 2017 - 16
Canadian Dam Association Bulletin - Summer 2017 - 17
Canadian Dam Association Bulletin - Summer 2017 - 18
Canadian Dam Association Bulletin - Summer 2017 - 19
Canadian Dam Association Bulletin - Summer 2017 - 20
Canadian Dam Association Bulletin - Summer 2017 - 21
Canadian Dam Association Bulletin - Summer 2017 - 22
Canadian Dam Association Bulletin - Summer 2017 - 23
Canadian Dam Association Bulletin - Summer 2017 - Hurricane Igor's Impact on Newfoundland Power's Small Hydro
Canadian Dam Association Bulletin - Summer 2017 - 25
Canadian Dam Association Bulletin - Summer 2017 - 26
Canadian Dam Association Bulletin - Summer 2017 - 27
Canadian Dam Association Bulletin - Summer 2017 - 28
Canadian Dam Association Bulletin - Summer 2017 - 29
Canadian Dam Association Bulletin - Summer 2017 - 30
Canadian Dam Association Bulletin - Summer 2017 - 31
Canadian Dam Association Bulletin - Summer 2017 - 32
Canadian Dam Association Bulletin - Summer 2017 - 33
Canadian Dam Association Bulletin - Summer 2017 - 34
Canadian Dam Association Bulletin - Summer 2017 - 35
Canadian Dam Association Bulletin - Summer 2017 - CDA Conference Heads to Kelowna!
Canadian Dam Association Bulletin - Summer 2017 - 37
Canadian Dam Association Bulletin - Summer 2017 - 38
Canadian Dam Association Bulletin - Summer 2017 - 39
Canadian Dam Association Bulletin - Summer 2017 - 40
Canadian Dam Association Bulletin - Summer 2017 - 41
Canadian Dam Association Bulletin - Summer 2017 - 42
Canadian Dam Association Bulletin - Summer 2017 - 43
Canadian Dam Association Bulletin - Summer 2017 - 44
Canadian Dam Association Bulletin - Summer 2017 - 45
Canadian Dam Association Bulletin - Summer 2017 - CDA Directors & Officers - Call for Nominations
Canadian Dam Association Bulletin - Summer 2017 - 47
Canadian Dam Association Bulletin - Summer 2017 - 2017 CDA Awards - Call for Nominations
Canadian Dam Association Bulletin - Summer 2017 - 49
Canadian Dam Association Bulletin - Summer 2017 - CDA Developing New Ways to Distribute Guidelines
Canadian Dam Association Bulletin - Summer 2017 - 51
Canadian Dam Association Bulletin - Summer 2017 - 52
Canadian Dam Association Bulletin - Summer 2017 - Notice of Annual General Meeting
Canadian Dam Association Bulletin - Summer 2017 - Time to Renew Your Membership
Canadian Dam Association Bulletin - Summer 2017 - Buyers' Guide and Trade List
Canadian Dam Association Bulletin - Summer 2017 - 56
Canadian Dam Association Bulletin - Summer 2017 - 57
Canadian Dam Association Bulletin - Summer 2017 - 58
Canadian Dam Association Bulletin - Summer 2017 - 59
Canadian Dam Association Bulletin - Summer 2017 - 60
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