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| Titel |
Erosion processes in granular flows: insights from laboratory experiments |
| VerfasserIn |
Maxime Farin, Anne Mangeney, Olivier Roche |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250072184
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| Zusammenfassung |
| Experimental granular column collapse were conducted over an inclined channel covered by
an erodible bed of granular material in order to reproduce at laboratory scale erosion
processes of natural flows propagating over deposits formed by earlier events. The studied
control parameters were the slope angle, the aspect ratio (i.e. height over length), the volume
and the shape of the granular column released, and the thickness and compaction of the
erodible bed. The results show that erosion processes affect the flow runout distance over a
critical slope angle θc that depends on the column volume, aspect ratio, and shape. For slope
higher than θc, the granular avalanche excavates the erodible layer immediately at the flow
front, behind which waves traveling downstream are observed and help entraining grains
from the erodible bed. Erosion efficiency (i.e. maximal depth and duration of excavation,
waves dimensions) is shown to increase as the slope angle and the column’s volume increase.
It is also dependent on the aspect ratio and on the nature of the erodible bed: the
maximal excavation depth and the duration of the excavation decrease as the degree of
compaction of the erodible granular bed increases. Erosion processes notably increase
granular flows runout distance at inclinations close to the repose angle of the grains, in
particular for columns of small aspect ratio. We demonstrate, however, that the flow
runout distance observed on an erodible bed cannot be reproduced on a rough bed by
simply adding the entrained volume of erodible bed to the initial column volume. |
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