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| Titel |
Experimental study on the rheological behaviour of debris flow |
| VerfasserIn |
A. Scotto di Santolo, A. M. Pellegrino, A. Evangelista |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1561-8633
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| Digitales Dokument |
URL |
| Erschienen |
In: Natural Hazards and Earth System Science ; 10, no. 12 ; Nr. 10, no. 12 (2010-12-07), S.2507-2514 |
| Datensatznummer |
250008530
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| Publikation (Nr.) |
 copernicus.org/nhess-10-2507-2010.pdf |
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| Zusammenfassung |
| A model able to describe all the processes involved in a debris flow can be
very complex owing to the sudden changing of the material that turns from
solid into liquid state. The two phases of the phenomenon are analysed
separately referring to soil mechanics procedures with regard to the trigger
phase, and to an equivalent fluid for the post-failure phase. The present
paper is devoted to show the experimental results carried out to evaluate
the behaviour assumed by a pyroclastic-derived soil during the flow. A
traditional fluid tool has been utilized: a standard rotational rheometer
equipped with two different geometries. The soils tested belong to deposits
that cover the slopes of the Campania region, Italy, often affected by debris
flows. The influence of solid concentration Cv and grain size
distribution was tested: the soils were destructurated, sieved and mixed
with water starting from the in situ porosity. All material mixtures showed
a non-Newtonian fluid behaviour with a yield stress τy that
increases with a solid volumetric concentration and decreases for an increase
of sand fraction. The experimental data were fitted with standard model for
fluids. A simple relation between Cv and τy was obtained. The
yield stress seems to be a key parameter for describing and predicting the
post-failure behaviour of debris flows. These results suggest that in the
field a small change in solid fraction, due to rainfall, will cause a slight
decrease of the static yield stress, readily inducing a rapid flow which
will stop only when the dynamic yield stress is reached, namely on a much
smoother slope. This can explain the in situ observed post-failure behaviour
of debris flows, which are able to flow over very long distances even on
smooth slopes. |
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