Design Experience on Slope Stability for Rockfill Dams, Turkey

Turkey has a good practice in construction of embankment dams. Up-to now, 95 percent of all dams, which have been constructed by various organizations, are categorized into earthfill or rockfill dams. In this study, slope stability of seventeen large rockfill dams having a height of 70 m to 169 m from river bed were re-analyzed by means of software as based on material properties given in their planning reports. In the context of this study, there are large dams located on very active seismic regions as well as large dams on the sites having low seismic activity. Analyses includes end-of-construction stage for downstream and upstream slopes, rapid drawdown stage from maximum water level and gate level, operation stage for partly and fully storage, and earthquake stage for end-of-construction and operation stages. This study indicates that deviation on safety factors increases for the cases located on site having low seismic activity. For the area having low seismic activity, rapid drawdown case is more critical when considered upstream slope stability. In Turkish design practice, downstream slope is selected as little steeper than upstream slope for rockfill dams for usual cases.