Probabilistic assessment of inner slope stability in dikes: Gaining insight in the difference between the semi-probabilistic and probabilistic estimates of the reliability index for inner slope stability with overtopping

After overtopping, the most common failure mechanism in the world that leads to a dike breach is the instability of the inner slope. Two stability calculations are required for the semi-probabilistic assessment of inner slope stability. One calculation is without significant overtopping and the other calculation is with significant overtopping...

Fragility Curves for Dikes in the Western Scheldt: Assessing the Applicability of Typology-Based Fragility Curves in assessing Dike Reinforcement Cost for Coastal Dikes

The sea level is rising, possibly by one meter, by the end of this century. The Netherlands is preparing for this scenario through Kennisprogramma Zeespiegelstijging (KP-ZSS). One of the goals is to determine the hydraulic effects of sea level rise (SLR) on the current system. For the flood risk analysis within<br/>KP-ZSS, the current strength...

Schematization of shear strength: The influence of the schematization of the shear strength on the macro-stability safety assessment

The Water Authority Rivierenland is responsible for periodically assessing the safety of the dike trajectories in the Alblasserwaard region. In 2012, the safety assessment for inner slope macro-stability was performed based on stress dependent design values for the shear strength, based on the cell test<br/>collection of the Water Authority. The...

A surrogate model approach to study the effect of rainfall through cracks on the macro-stability of canal dikes

Under the current climate change projections, droughts and extreme rainfall events are becoming more common and intense. During sustained droughts, soil cracks can develop in the topsoil of a dike. These soil cracks can enhance the infiltration and drainage of the dike, affecting the dike stability. This study’s main objective is to better...

The increase of dike stability due to unsaturated soil strength: A study of the spatially and temporally varying presence of matric suction

River dikes in the eastern part of the Netherlands are characterized by a relatively low daily water table. In the unsaturated zone above the water table, a negative pore pressure (matric suction) is present that binds the soil particles together. Suction can be especially large in soils with small grains, such as clay, and increases the...

Visualization of the Random Material Point Method for macro-instability

To protect the Netherlands better from flooding, and with an eye on sea-level rise in the rest of the world, more accurate assessments are needed for dykes. The calculation for the most occurring failure mechanism in dykes, i.e. macro-instability, is limited by not being able to calculate large deformation when sliding occurs within a dyke. The...

Assessment of macro-instability using SHANSEP in RFEM: The application of SHANSEP in combination with RFEM for safety assessment of dikes.

The Dutch Water board revised their guidelines for the safety assessment of dikes in 2017. A major change for the assessment of macro-stability is the use of the SHANSEP method to estimate the strength of impermeable cohesive layers. The failure probabilities are estimated with a deterministic analysis using limit equilibrium methods. The use of...

Revision of the calibration equation for a river dike on macro stability

Two types of calculations are currently used to assess dikes for macro stability. These are the semi-probabilistic calculation and the probabilistic calculation. In practice, the semi-probabilistic calculation is currently mostly used. However, the probabilistic calculation is the most accurate calculation of the two methods resulting in the...

Dike stabilisation under uplift conditions using stabilisation columns: A study on the technical potential of stabilisation columns for improving inner slope stability under uplift conditions

The low lying areas in the Netherlands often consist of soft and low permeable soils like clay and peat on top of a sand layer. Due to high water pressures at the interface between the permeable sand layer and the low permeable top layers, the effective stresses decrease, which can cause lifting of the low permeable top layers. As a consequence...

The unexpected softening of the undrained shear strength of organic and silty clays in Rhine delta: a conceptual study: Determining the Undrained Shear Strength of soft Dutch soils using conventional laboratory equipment

The current Dutch norms for the macro-stability of ood protection embankments and more specifically the determination of SHANSEP parameters has been subject of debate since its implementation in 2017. The main concerns arise from the apparent over-conservative nature of the guidelines and the apparent underestimation of shear strength of organic...

Mass stabilisation near regional flood defences: A technical feasibility study into the application of mass stabilisation for improving the inward macro-stability of regional flood defences

Reinforcing levees with traditional methods is becoming more difficult in the Netherlands. Often there is a lack of space near the levee or it is desired that the landscape is maintained. Because of this, alternative methods for reinforcing levees are still sought after (CUR-commissie C141, 2007). In this study, the technical feasibility of a...

An Analysis of the Phreatic Surface of Primary Flood Defences

PLAXIS study of a primary flood defence in the Netherlands. The influence of water level, precipitation, and wave overtopping on the position of the phreatic surface is being investigated. The hydraulic loads are applied to a clay dike with a cracked top layer and a sand dike with a cracked clay cover. The findings are related to the current...

Safety assessment method for macro-stability of dikes with high foreshores

This Thesis studies the safety assessment method for macro-stability of dikes with high foreshores. Currently, this method is a semi-probabilistic method, which does not take the presence of a foreshore into account. The research concludes that the presence of a foreshore has a significant influence on the failure probability with respect to...

Study upon the possible influence of animal burrows on the failure of the levee of San Matteo along the Secchia river

Animal burrowing can be a main cause of initiation thereby be a cause of breaching of flood defences. However, little guidance and literature is available on this subject. This Master Thesis investigates the contribution of badgers, porcupines and foxes to the failure of the levee of San Matteo (Modena, Italy) on 19th January 2014. Firstly, the...

Overview geotechnical model tests on dike safety at Deltares

Three on-going dike safety studies (on: macro stability, piping and flow slides) in the Netherlands make use of geotechnical physical models. A short outline of these projects is presented; the physical models chosen are described and discussed. The three studies use different physical models, depending on the research questions at the beginning...