Semi-probabilistic assessments of the stability of block revetments under wave attack – columns

This report presents the calibrated safety factors for semi-probabilistic assessments of the stability of columns (in Dutch: "zuilen") under wave attack. The results of this study will serve as input for a decision on the safety factors that are to be used for block revetments in general in the WT12017. The calibrated safety factors range from 1.18 to 1.07, for safety standards rangingfrom 1/300 to 1/30,000 per year. This is more stringent than the WT12011'soverall safety factor of 1.0. It should, however, be noted that the calibrated safety factors could be lowered when the residual strength of filter and base layers is significant.A residual strength model is currently under development. With this model, it will become possible to quantify the impact of the residual strength of filter and base layers on the calibrated safety factors. The calibrated safety factors should only be applied in safety assessments of existing revetments; they should not be used for design purposes.