The effect of interactions between failure mechanisms on the reliability of flood defenses

Structural reliability analysis often considers failure mechanisms as correlated but non-interacting processes. Interacting failure mechanisms affect each others performance, and thereby the system reliability. We describe such interactions in the context of flood defenses, and analyze under which conditions such interactions have a large impact...

Reliability updating for slope stability: Improving dike safety assessments using performance information

Dikes are crucial for the protection against floods. One of the ways in which dikes can fail is by the instability of the inner slope. Credible probabilities of failure for slope stability are essential for the safety assessment of existing dikes and the design of dike reinforcements. This dissertation focuses on improving failure probability...

Storyline: Proof loading and monitoring to optimise flood defence asset management

Project Summary D4 - Incorporating past performance: Improved methods for estimating dike failure probability

Improving dike reliability estimates by incorporating construction survival

During construction of a dike, slope stability often reaches critical levels, due to the excess pore water pressures in the foundation. The loading condition during construction has similarities with the design conditions during flood loading. Not only in terms of the pore water pressures as the main driving force, but also in terms of...

Value of information of combinations of proof loading and pore pressure monitoring for flood defences

Spatial variability and limited measurements often result in low reliability estimates of geotechnical failure modes of dikes (i.e., earthen flood defences). Required dike reinforcements are usually not executed within a few years after inception, which enables efforts to improve reliability estimates by reducing uncertainty. Often decision...

Systematic Transformation Error in the Depth-Average Undrained Shear Strength

In this paper we show how to calibrate a site-specific transformation model to measure the undrained shear strength from CPTs. This practically unbiased transformation model can then be used to make a better estimation of the spatial average parameter, such as the depth-average of a soil layer in a homogenous deposit, using less costly indirect...

Do all dike instabilities cause flooding?

One of the failure mechanisms of dikes is slope instability at the landward side. Often, one instability does not lead to flooding, and several successive instabilities are needed before the dike overtops, and erosion and breaching can occur, especially at lower water levels. In this paper we propose a method to estimate the probability of...

Uncertainty in spatial average undrained shear strength with a site-specific transformation model

Transformation models are used to infer geotechnical properties from indirect measurements. A site-specific transformation model can be calibrated with direct and indirect measurements from a site. When such a model is used, then spatial variability, measurement errors and statistical uncertainty propagate into the uncertainty of the spatial...

Calibration of Factors of Safety for Slope Stability of Dikes

Dikes in the Netherlands are by law required to comply with predefined safety standards. The goal of this paper is to derive the safety format and the required factor of safety for the inner slope (landside slope) instability failure mode. The first step is to derive the required target reliability for a cross-section. The second step is to...

Reliability Updating with Survival Information for Dike Slope Stability Using Fragility Curves

Dikes and levees play a crucial role in flood protection. The main causes of levee failures are of geotechnical nature. Geotechnical failure modes are also the main contributors to the probability of failure of flood defenses such as levees due to the large uncertainties in ground conditions. Hence, information on ground conditions and soil...

Safety Assessment Method of Flood Defences for Flow Sliding

Flow sliding of submerged slopes in front of dikes can affect the reliability of flood defences. The occurrence of flow sliding may result, sometimes with delay, in a failure mode and consequent flooding. The current safety assessment method for flow sliding does not consider the interaction between flow sliding and failure modes which can cause...

Safety Assessment Method of Flood Defences for Flow Sliding

Flow sliding of submerged slopes in front of dikes can affect the reliability of flood defences. The occurrence of flow sliding may result, sometimes with delay, in a failure mode and consequent flooding. The current safety assessment method for flow sliding does not consider the interaction between flow sliding and failure modes which can cause...