Post-Construction Behavior of Round Butte Dam

The 440-ft high rockfill dam in the deep canyon of the Deschutes River in central Oregon was constructed of brittle, nonplastic core material, processed transition zones, and rock, on an irregular foundation consisting of basalt rock and stratified sediments containing other strata of basalt rock. The control of seepage through the open-jointed and multilayered basalt was one of several design and construction problems. Selection of the site, dam, design, and provisions for control of abutment seepage and related construction are described. Settlement and deflection of the dam, associated longitudinal and transverse cracking, and the effectiveness of seepage control in the abutments as indicated by piezometric and seepage measurement, are considered.