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| Titel |
Enhanced stability of hillslopes and channel beds to mass failure |
| VerfasserIn |
Jeff Prancevic, Michael Lamb, Marisa Palucis, Jeremy Venditti |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250130292
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| Publikation (Nr.) |
 EGU/EGU2016-10528.pdf |
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| Zusammenfassung |
| The stability of inclined, unconsolidated sediments subjected to groundwater flow on
hillslopes and steep channel beds is important for both landscape evolution and natural
hazards. Force-balance models have been used for seven decades to predict the stability of
slopes, but they generally underpredict the degree of saturation required to destabilize the
sediment. Researchers often appeal to heightened stabilizing forces from root and mineral
cohesion, and friction acting on the margins of the failure to explain this underprediction.
Surprisingly, infinite-slope stability models in their simplest form have never been tested
under controlled laboratory conditions. To address this gap in data, we perform a set
of controlled laboratory experiments with slope-parallel seepage in the simplest
possible configuration. We performed 47 experiments in a 5 m laboratory flume
with 4 grain sizes (D50 = 0.7, 2, 5, and 15 mm) and a wide range in bed angles
(20∘ to 43∘), spanning both Darcian and turbulent subsurface flow regimes. Our
experiments show that granular slopes were more stable than predicted by simple
force balance models in experiments that lack root or mineral cohesion. Despite
the smooth plastic walls and the long aspect ratio of our flume, we calculate wall
and toe friction to be important. Including these additional resistance terms in the
model reduces the model misfit with our experimental results. However, there is
considerable remaining misfit (up to 50% underestimation of the saturation level
required for failure). We investigate two explanations of this heightened stability: 1)
standard frictional resistance terms are underestimated, and 2) seepage stresses are
overestimated. Both explanations require that we modify the models used to predict slope
stability. |
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