Development of Fragility Curves for Piping and Slope Stability of River Levees

Abstract

The design code Eurocode 7 relies on semi-probabilistic calculation procedures, through utilization of the soil parameters obtained by in situ and laboratory tests, or by the means of transformation models. To reach a prescribed safety margin, the inherent soil parameter variability is accounted for through the application of partial factors to either soil parameters directly or to the resistance. However, considering several sources of geotechnical uncertainty, including the inherent soil variability, measurement error and transformation uncertainty, full probabilistic analyses should be implemented to directly consider the site-specific variability. This paper presents the procedure of developing fragility curves for levee slope stability and piping as failure mechanisms that lead to larger breaches, where a direct influence of the flood event intensity on the probability of failure is calculated. A range of fragility curve sets is presented, considering the variability of levee material properties and varying durations of the flood event, thus providing crucial insight into the vulnerability of the levee exposed to rising water levels. The procedure is applied to the River Drava levee, a site which has shown a continuous trend of increased water levels in recent years.

Fragility analysis of slopes exposed to seismic hazard employing surrogate modeling techniques

“…Fragility analysis considering parameter uncertainties of mechanical and geometric properties have been applied to obtain fragility curves for different hazard scenarios [8][9][10]. Moreover, seismic fragility curves for slope stability have been developed using different approaches such as incremental dynamic analysis, however, it conveys a great computational cost associated with performing the required series of dynamic time history analyses [11].…”

Fragility Curves for Slope Stability of Geogrid Reinforced River Levees

“…Thus, probabilistic analyses are conducted with the objective of quantifying the effects of uncertainties related to geogrid reinforcement on the slope stability of levees, and to construct fragility curves which show the probability of failure of the levee for any water level. Such probabilistic slope stability analyses can be conducted using numerous methods [35][36][37][38][39][40][41][42][43]. In this study, the limit equilibrium method is adopted due to its simplicity and wide usage in geotechnical practice, while results are further processed with programmed probabilistic methods to find the probabilities of unwanted behavior of the levee subjected to various water levels with steady state conditions.…”

Dam Safety-Overtopping and Geostructural Risks

“…Three papers are directly related to the development of fragility curves that are necessary for the risk assessment [9][10][11]. The fragility curves represent the probability of failure, or a certain level of damage, depending on a parameter that defines the intensity of the main action that might cause the failure.…”

“…However, the contribution of the geogrid layer located at the highest level is greater than that of the rest layers. Based on a probabilistic characterization of soil properties and the use of numerical modeling, the same authors [11] developed fragility curves for piping and slope stability of river levees and applied them to the river Drava levee. Probability of failure depends on the water level in the river, including overflow scenarios.…”