Water Stewardship Information Sources
| Citation | Atukorala, U, Hawson, H, Mylleville, B and Williams, R. 2014. Seismic Design Guidelines for Dikes, 2nd Edition. BC Ministry of Forests, Lands and Natural Resource Operations. |
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| Organization | FLNRO |
| URL | http://www.env.gov.bc.ca/wsd/public_safety/flood/pdfs_word/seismic_guidelines_dikes-2014-2nd_edition.pdf |
| Abstract/Description or Keywords | The purpose of this document is to provide guidelines for consideration of seismic stability and integrity of the High Consequence Dikes in Southwestern British Columbia and Vancouver Island with the intent to provide flood protection for the densely populated urban communities and regional infrastructure. Guidelines are provided on: Seismic ground motions to be considered for the analysis and design of dikes along with corresponding performance expectations; Suitable geotechnical investigation methods to characterize and obtain engineering properties of the site soils; Commonly used methods for seismic analysis considered appropriate for dikes; Seismic rehabilitation and strengthening measures; Threshold seismic events that should trigger a post-event evaluation of the integrity of the dike system; and Post-earthquake temporary emergency repair and permanent remediation measures. The west coast of British Columbia, including Vancouver Island, is a region of high seismic hazard in Canada. The seismic hazard is caused by the Juan de Fuca Plate subducting under the North American Plate resulting in large earthquakes of magnitude varying from Mw6 up to Mw9. Densely populated urban communities and regional infrastructure in British Columbia are protected from flooding by some 300 km of river and sea dikes. The original dikes constructed in the early years were levees built with local fills and to very rudimentary standards. These dikes were upgraded in the 1970s and 1980s to design standards that existed at that time. During these upgrading works, the potential for earthquake-induced soil liquefaction and associated potential for damage was reviewed, but the cost to design for seismic loading was not judged to be commensurate with the consequences to the community. Since that time, municipalities throughout the Lower Mainland have seen extensive population growth and the consequences to the communities and infrastructure has increased. The extent of damage resulting from large scale flooding resulting from breaches to the different diking systems has been estimated to reach upwards of $50 Bn (2013 dollars). Flood protection dikes are almost always located along river banks and shorelines that have historically experienced considerable damage following earthquakes. Therefore, dikes have a high geo-hazard exposure and need to be investigated in detail to allow identification and assessment of soil strata that are vulnerable to liquefaction, loss of shear strength, and displacement during seismic design. This guideline has adopted a combination of traditional and performance-based design criteria for the seismic design of dikes. Dike performance is specified in terms of measureable criteria such as crest displacements of the dike structure. The methodologies and criteria provided in the document were established following a review of practices currently followed in other regions of the world that are also prone to high seismic hazards. |
| Information Type | report |
| Regional Watershed | Province |
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| Project status | complete |
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