Opdrijven, opbollen, opbarsten
Improving the uplift model for the assessment of internal erosion
P.Y. Tao (TU Delft - Civil Engineering & Geosciences)
R.C. Lanzafame – Mentor (TU Delft - Hydraulic Structures and Flood Risk)
Philip J. Vardon – Graduation committee member (TU Delft - Geo-engineering)
M. van Damme – Graduation committee member (TU Delft - Hydraulic Structures and Flood Risk)
Rimmer Koopmans – Graduation committee member (ARCADIS Nederland)
Leo Kwakman – Graduation committee member (ARCADIS Nederland)
More Info
expand_more
Other than for strictly personal use, it is not permitted to download, forward or distribute the text or part of it, without the consent of the author(s) and/or copyright holder(s), unless the work is under an open content license such as Creative Commons.
Abstract
Internal erosion is a frequent cause of dike failure, also known as piping or backward erosion. Uplift is considered a submechanism of internal erosion, together with heave and piping, where all three submechanisms must occur for the dike to reach a failure condition. The principle of the uplift phenomenon is straightforward: it occurs when high pore water pressures in the aquifer lift the cover layer, which is located at ground surface. If the pressure is great enough, the cover layer begins to float ('opdrijven'), and may also bulge ('opbollen') or crack ('opbarsten'). Currently, the assessment for uplift is based on a vertical equilibrium, which relates to a floating condition of the cover layer. The forming of an exit point for concentrated seepage is presumed to happen simultaneously with the increase in uplift pressure and is therefore not explicitly considered in the current assessment. This thesis aimed to investigate in what way the uplift assessment may be improved, both to describe the complex behavior better and to decrease the need for costly countermeasures. The evaluation of uplift was conducted in two parts: by making explicit what the causes of uncertainty are in the current assessment, as well as by proposing a new model to describe the complete uplift behavior better. It is recommended to evaluate the ‘floating’ and ‘bulging-cracking’ phases directly. In the ‘bulging-cracking’ phase, the forming of an exit point can either occur by a tension or shear failure.