A Metamodelling Approach to Reliability Updating with Dike Construction Survival

Abstract

The construction of a dike improvement often causes a decrease in reliability during construction. Raising a dike may give rise to excess pore water pressures in the subsoil, resulting in a temporal strength decrease. Observing the survival of such a loading condition might provide information on the strength of a dike. Therefore, this research investigates the effect of incorporating construction survival in estimating the slope reliability of dikes. Assessing slope reliability can be done by means of simulation. However, due to the high reliability of dikes, many realizations and thus model evaluations may be needed to achieve sufficient accuracy, leading to infeasible computation times. In this research, a method is developed for reliability updating using metamodelling, providing reasonable computation times while not losing accuracy. The effect of incorporating construction survival is explored by updating the inward slope reliability of a case study dike improvement. The case study shows that the current semi-probabilistic approach to assessing construction stability in practice leads to situations not effective for reliability updating. Though adjusting the construction phasing may lead to a significant update. It is shown that adapting the dike improvement design after survival of the critical construction step results in a 75% reduction of the dimensions of the berm to be constructed, while achieving the same reliability as prior to the update. The main finding of this research is that incorporating construction survival in the reliability assessment can be very effective in terms of reliability, and in making dike improvements more efficient and less space consuming.