Page - 736 - in Book of Full Papers - Symposium Hydro Engineering

COMMISSION INTERNATIONALE DES GRANDS BARRAGES ------- VINGT-SIXIÈME CONGRÈS DES GRANDS BARRAGES Autriche, juillet 2018 ------- JUSTIFICATION FOR SELECTING A FACTOR OF SAFETY FOR DAMS Thomas Konow Head of Dam Safety, DR. TECHN. OLAV OLSEN Mathias Strand Special Adviser - Advanced Analyses, DR. TECHN. OLAV OLSEN NORWAY 1. INTRODUCTION Requirements for stability of concrete dams in the current Norwegian dam safety regulations are based on simplifications, which in many cases are conservative. As a result, rehabilitation works may be carried out on dams that are safe, but does not meet the safety requirements. Norwegian dams have to meet a minimum safety standard, defined by a Factor of Safety (FoS). It is often assumed that the FoS includes all of the uncertainties in the calculations. However, how these variables affect the FoS are generally not known or not accessible. It is therefore a need to acquire more knowledge on how different assumptions affect the calculations of stability of FoS. How different parameters affect the dam stability is essential in order to identify which parameters that are most important for stability and sensitivity of the overall dam safety. This knowledge is of particular interest in assessing existing dams. By gaining more knowledge about different parameters, it is possible to reduce the uncertainty connected to these parameters, and thereby reducing the overall uncertainty. This knowledge can thereby be used to reduce the calculated FoS without affecting the safety level of the dam. 736