Effects of embankment breach position on characteristic of failure.

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Pongpan Kanjanakaroon, CHAIWAT EKKAWATPANIT, Sanit Womgsa, Udomsak Israngkura, Duangrudee Kositgittiwong

Tuesday 30 june 2015

9:00 - 9:15h at South America (level 0)

Themes: (T) Water engineering, (ST) River and coastal engineering

Parallel session: 4J. Floodrisk – Flooding

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Many studies of embankment failure from overtopping flow have been studies in various topics but most topics concern about the mechanism of breach, erosion of depth and wide, and breach hydrograph. Although all studies of physical model, mathematical model and couple model, position to the breach which can be eroded in both sides, sometime the breach occurs near fix structure which cannot be eroded. The aim of the research are, to define mechanism of the surface erosion and/or headcut erosion in the embankment which cannot erode base on the cohesive embankment breach model, and to investigate the relationship between breach width and depth under variant condition of embankment. Physical models are used to analyze the relationship between parameters and demonstrate the state of failure. The flow at the breach is measured using venture flume in downstream. Three breach positions including near structure (X1), middle of embankment width (X3) and between X1 and X3 (X2) and vary with different three embankment slopes are 1:1, 1:1.5 and 1:2. The results show that, under the same embankment slope and discharge, mechanism of embankment breach in all positions started with surface erosion and develops to headcut erosion by jet scour at the toe of embankment. Soil volume of three cases, X1, X2 and X3, are quite similar. Embankment breach width at X3 is wider than X2 and X2 is wider than X1. In contrast, breach depth of X1 is deeper than X2 and X2 is deeper than X3. It was found that breach position does not have an effect on volume of soil erosion but it affects breach depth and width. If the breach position is closed to the structure or non-erodible material, the depth of breach is deeper than normal and it can be impact the foundation of structure.