Page - 1005 - in Book of Full Papers - Symposium Hydro Engineering

chart, f and N represent the annualized failure probability and the estimated life loss associated with an individual failure mode, respectively. The f-N chart has been presented in Fig.3. Fig. 3. The f-N diagram of risk analysis results Where; Priority A- Justification to take expedited action to reduce risk Priority B- Justification to take action to reduce risk Priority C- Diminishing justification to take action to reduce risk As it can be seen, the most critical risk comes from erosion through layered soil foundation (PF1), but all the risks of dam failure by erosion in right abutment of Ahmadbeiglu dam is in Priority C that indicate a reduced justification for risk reduction action related to these failure modes. For increase safety, in addition to the instruments of dam body and foundation in right abutment, instruments such open standpipe piezometers (at the downstream of clay core and foundation) for checking pore water pressure in foundation and downstream of clay core and observation wells (at the downstream of dam body and right abutment) for evaluation ground water level at the downstream and right abutment have been installed. ACKNOWLEDGEMENTS The authors appreciate the cooperation of the Ardebil Regional Water Authority and Pooyab Consulting Engineers. The authors would also like to acknowledge Engineer Nosratollah Mostofi, the head of geology department of Pooyab Consulting Engineer, for providing of geological information of Ahmadbeiglu Storage Dam Site. 1005