29 - The Use of Rock Engineering to Overcome Adverse Geology at Revelstoke Dam

Abstract

This chapter presents the use of rock engineering to overcome adverse geology at Revelstoke Dam. Revelstoke Dam consists of a 160 m high concrete gravity dam, a powerhouse immediately downstream of the dam in the riverbed, a three-bay gated chute spillway on the west bank, and an earthfill dam across the west bank terrace. The bedrock underlying the Mica and Revelstoke damsites consists mainly of paragneissic rocks within the fringe of the Shuswap and Monashee metamorphic complexes. This metamorphic assemblage underlies a broad area of south-central British Columbia, west of the Rocky Mountain Trench. Within the region underlain by rocks of the Shuswap and Monashee complexes, a number of oval-shaped centers of metamorphism occur; these are surrounded by aureoles of different metamorphic zones. Regional geological mapping of the area surrounding a project site is mandatory and should be carried out during the preliminary design phase of the project at a scale that is intermediate between normal site mapping and standard geological survey maps from federal agencies. Rock foundation stability analyses should use a friction-based analysis rather than a classical friction–cohesion analysis to reflect the actual foundation rock and defect strengths better.