Reliability-based analysis of river dikes during flood waves

Reliability and risk analyses are basic approaches, nowadays, for flood risk assessments in European countries such as the Netherlands, German, United Kingdom, etc. The methods also receive a lot of interest in developing countries. By considering uncertainties for both load and strength variables, the probability of failure for each element of the flood defence system can be formulated. This paper focuses on the reliability analysis of the Red river dike during a typical flood wave of 1/500 year frequency in which the soil properties (unit weight, grain size, its thickness under the dike, etc) are modelled probabilistically. Harmonic functions are fitted for the predicted flood wave and the unsteady groundwater how under the river dike is considered with delay and decay detection from piezometer observation data. Uncertainties are analysed and failure probabilities of some geotechnical phenomena under the river dike such as piping and instability have been calculated with different water levels.