Analysis of foundation settlements at Ridgway Dam

The foundation material at the Ridgway Dam site is broadly classified as mudstone. The observed foundation settlements along the invert of the river outlet-works conduit at Ridgway Dam are on the order of 0.3 m. Numerical analyses were performed to estimate the deformation properties for a foundation material that under the existing embankment loads would deflect in a manner similar to the settlements surveyed along the invert of the outlet-works conduit. The foundation deformation properties determined from these analyses are compared with those obtained through the laboratory testing of the site-specific foundation materials and the published data. The results of the analyses, the field instrumentation data, the site geology, and the laboratory data provided an input to the decision-making process for the rehabilitation of the river outlet- works conduit. Key words: foundations, settlements, embankment dams, mudstones, analysis.