University of Twente Student Theses


Possibilities for improving assessment tools of dikes safety

Tran, Trung Quoc (2012) Possibilities for improving assessment tools of dikes safety.

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Abstract:Currently, Edelman – Joustra equation is used as an assessment tool for evaluating dike safety in terms of potentially surficial sliding. Application of this statutory is relatively simple, but gives a conservative judgment since it stemmed from one-dimensional analysis. In practice, many dike sections are still safe even though the Edelman – Joustra condition is not satisfied. In those cases, further detailed evaluations are usually required, including groundwater flow and advanced stability analyses. To some extent, such costly and time-consuming tests can be avoided if the accuracy of the current criterion is improved sufficiently. To achieve this, the 1-D method using Edelman – Joustra equation was compared to other detailed analyses, namely Spencer and finite element method (FEM – PLAXIS) through a set of parametric calculations. The calculations showed that the accuracy of the one-dimensional Edelman – Joustra equation can be improved by including the effect of L/D ratio. In this ratio, L is the slope length and D is the thickness of the cover layer. With a formulae determining the influence of L/D ratio on sliding mechanism, the accuracy can be improved up to 15% for ratios smaller than 25. This result holds for most conventional dikes. In order to show and determine practical usefulness of the improved function, verification and validation steps have been executed, together with a case study – Afsluitdijk. As part of this case study, the influence of wave overtopping on downstream slopes stability was simulated, of which infiltration process demonstrates a simple method connecting hydraulic loadings and soil mechanics. In conclusion, an improved safety assessment method was developed, which is useful in instances. Consequently, the improved method has been included in an integrated proposal to improve the current assessment guidelines so that the costly and time-consuming evaluations can be avoided as much as possible in the future.
Item Type:Essay (Master)
Faculty:ET: Engineering Technology
Subject:52 mechanical engineering
Programme:Mechanical Engineering MSc (60439)
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