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| Titel |
Experimental Modelling of Debris Flows |
| VerfasserIn |
P. Paleo Cageao, B. Turnbull, P. Bartelt |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250062962
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| Zusammenfassung |
| Debris flows are gravity-driven mass movements typically containing water, sediments, soil
and rocks. These elements combine to give a flow complex phenomenology that
exhibits characteristics common to diverse geophysical flows from dry granular
media (e.g. levee formation) to viscous gravity currents (viscous fingering and surge
instabilities). The exceptional speeds and range debris flows can achieve motivate the
need for a co-ordinated modelling approach that can provide insight into the key
physical processes that dictate the hazard associated with the flows. There has been
recent progress in theoretical modelling approaches that capture the details of the
multi-component nature of debris flows. The promise of such models is underlined by their
qualitatively successful comparison with field-scale experimental data. The aim of the
present work is to address the technical difficulties in achieving a controlled and
repeatable laboratory-scale experiment for robust testing of these multi-component
models.
A laboratory experiment has been designed and tested that can provide detailed
information of the internal structure of debris flows. This constitutes a narrow Perspex chute
that can be tilted to any angle between 0° and - 60°. A mixture of glycerine and
glass balls was initially held behind a lock-gate, before being released down the
chute. The evolving flow was captured through high speed video, analysed with a
Particle Image Velocimetry algorithm to provide the changing velocity field. A wide
parameter space has been tested, allowing variations in particle size, dispersity, surface
roughness, fluid viscosity, slope angle and solid volume fraction. While matching
key similarity criteria, such as Froude number, with a typical field event, these
experiments allow close examination of a wide range of physical scenarios for the
robust testing of new multi-component flow models. Further diagnostics include
force plate and pore pressure measurements, with a view to gaining insight into the
interaction between fluid and particles, and for direct comparison with similar field-scale
measurements. Here, details of the experimental design, initial results and their analysis will
be discussed and contrasted with predictions of new multi-component theoretical
models. |
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