Author: Katrina T. Wechselberger, Egbert J. Scherman
Conference: CDA Annual Conference
Date: October 15-20, 2016
Canada’s extensive and aging dam infrastructure in combination with the updated and revised Dam Safety Regulations often require re?examining previously satisfactory analysis and developing a greater understanding of the cumulative and independent effects of a series of common design assumptions. Knight Piésold Ltd. recently completed a seismic and structural stability analysis on the Corra Linn Dam and Spillway located on the Kootenay River, approximately 15 km downstream of the city of Nelson, British Columbia.
Originally constructed in 1932, the dam and hydroelectric facility underwent repairs and upgrades as recent as 1990. The work consisted primarily of concrete re?surfacing, the installation of post?tensioned rock anchors to add the dam’s stability, and the installation of piezometers to measure seepage under the dam and into the rock foundation. It was recommended in the latest Dam Safety Review (DSR) that the seismic stability of the dam structures be reassessed with the larger design earthquake values, in this case the Maximum Credible Earthquake (MCE).
Two separate 3D Finite Element Analysis (FEA) software programs were used to complete the analysis: Strand7 Software and ANSYS Simulation Software. This allowed for some confirmation of the results between programs and users. Pseudo?Static and Spectral Response analyses were performed. The various unknown factors such as actual material strengths, cracked structure/rock interface, etc. commonly encountered in a structure of advanced age can easily lead to compounded conservative assumptions. Where potential weaknesses are found it is important to understand what has contributed most significantly to the results so that recommendations can be well informed and clearly identify where further investigation is warranted.
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