ABSTRACT
Ribeiradio dam, located on Vouga River, Portugal, is the main dam of the multipurpose hydro-scheme of Ribeiradio-Ermida. It is a concrete dam with a gravity profile, with a maximum height of 83 m and a crest length of 265 m. Ribeiradio dam is founded on a granitic rock mass, predominantly constituted by medium to coarse grained granite. Initially in the foundation rock mass there were highly weathered and fractured rock zones until significant depths, especially in the upper elevations of the left bank and at intermediate elevations on the right bank. In the dam’s foundation, 34 vertical boreholes were drilled to obtain seismic velocity tomographies for various sections between boreholes. These tests were performed before (Phase 1) and after (Phase 2) the foundation treatment to improve the rock mass’s mechanical properties. In Phase 1, the seismic tomographies contributed to the geological-geotechnical zoning of the dam’s foundation. With the results of Phase 2, it was possible to evaluate the effectiveness of the rock mass treatment.
