Reliability analysis of the Red River dikes system in Viet Nam

Abstract

This dissertation presents the applications of probabilistic-based frameworks in geotechnical and hydraulic engineering, for the assessment of the Red River dikes in Viet Nam. Dike along rivers often spread over the deltaic environment and its earthen structures are parts of a long civilian history, from hundreds to thousands of years. Uncertainties of soil properties (resistance) of the dike embankment and its foundation, and contribute to the probability of failure under a given water level. Water level (load) composes uncertainty that relates to the variability of hydraulic boundary condition as well as the statistics at gauging stations. The probabilistic-based framework already proved its benefits by combining the uncertainties from both load and resistance, which will be applied in the study area. The calculation results indicate that during a long duration flood, the Red River dike system will be mostly threatened by piping. The proposed models of piping dealing with time have been calibrated by an actual dike failure, which are also applied to the assessment of the Red River dike system. Model factor significantly shows its benefits in the analysis of sand boils and some related phenomena. Overall, the Red River dikes in the Ha Noi area have a lower safety level than that we expected, which is indicated by a system reliability index when taking all failure mechanisms and dike stretches into account.