Briefing: Sliding safety of concrete dams through the comparison of different standards

For new dams on rock foundations, it may be feasible to review sliding safety under a very stringent rules approach. However, the task of identifying the most stringent standard is not always straightforward, as different approaches are seen to apply different criteria, with different levels of stringency applied to the different components of sliding resistance. This situation can give rise to complications in less competent foundations or in the case of deteriorating foundation strength on an existing concrete dam. Therefore, the main task of this paper is to assist in the challenge of identifying the most stringent standard or practice for assessing the sliding safety of concrete dams. Computational stability tests were carried out for an existing dam in accordance with European and American standards. Then the comparison of standards was carried out based on a parameter that represents the ratio of the assumed safety factor to the safety factor determined by use of a standard. The lower the established ratio, the more stringent the standard because the safety factor value reflects stringency. The paper also demonstrates that the stringency of a standard should be characterised by the contribution of friction and cohesion to the assumed safety factor.