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Title: Modelling embankment breaching due to overflow
Author: van Damme, Myron
ISNI:       0000 0004 5356 5937
Awarding Body: University of Oxford
Current Institution: University of Oxford
Date of Award: 2014
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Correct modelling of embankment breach formation is essential for an accurate assessment of the associated flood risk. Modelling breach formation due to overflow requires a thorough understanding of the geotechnical processes in unsaturated soils as well as erosion processes under supercritical flow conditions. This thesis describes 1D slope stability analysis performed for unsaturated soils whose moisture content changes with time. The analysis performed shows that sediment-laden gravity flows play an important role in the erosion behaviour of embankments. The thesis also describes a practical, fast breach model based on a simplified description of the physical processes that can be used in modelling and decision support frameworks for flooding. To predict the breach hydrograph, the rapid model distinguishes between breach formation due to headcut erosion and surface erosion in the case of failure due to overflow. The model also predicts the breach hydrograph in the case of failure due to piping. The assumptions with respect to breach flow modelling are reviewed, and result in a new set of breadth-integrated Navier-Stokes equations, that account for wall shear stresses and a variable breadth geometry. The vertical 2D flow field described by the equations can be used to calculate accurately the stresses on the embankment during the early stages of breach formation. Pressure-correction methods are given for solving the 2D Navier-Stokes equations for a variable breadth, and good agreement is found when validating the flow model against analytical solutions.
Supervisor: Martin, Chris Martin ; Borthwick, A. G. L. ; Morris, M. W. Sponsor: Flood Risk Management Research Consortium
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Fluid mechanics (mathematics) ; Numerical analysis ; Ordinary differential equations ; Partial differential equations ; Applications and algorithms ; Program development and tools ; Civil engineering ; Dynamics and ocean and coastal engieneering ; Geotechnical engineering ; Mathematical modeling (engineering) ; fluid dynamics ; embankments ; breach ; Navier-Stokes ; unsaturated soil ; erosion