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| Titel |
Gravitational wet-avalanche pressure on pylon-like structures |
| VerfasserIn |
Betty Sovilla, Thierry Faug, Anselm Köhler, Djebar Baroudi, Jan-Thomas Fischer, Emmanuel Thibert |
| 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 |
250136254
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| Publikation (Nr.) |
 EGU/EGU2016-17250.pdf |
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| Zusammenfassung |
| Low-speed wet-avalanches exert hydrostatic forces on structures which are surface-dependent,
however neither the pressure amplification experienced by smaller structure has been
quantified and the causes of the amplification understood. In particular, recent wet-snow
avalanche pressure measurements, performed with small cells at the "Vallée the la Sionne"
test site, indicate significantly higher pressures than those considered by engineering
guidelines and common practice rules based only on the contribution of inertial forces. In
order to gain a deeper understanding and investigate the relevance of these measurements
for structural design, we analyze data collected at the "Vallée the la Sionne" on
obstacles of different shapes and dimensions. We show that, the pressure measured on a
1 m2 pressure plate is, on average, 1.8 times smaller than the pressure measured
on a 0.008 m2 piezoelectric cell, installed on a 0.60 m wide pylon, and 2.9 times
smaller than the pressure measured on a 0.0125 m2 cantilever sensor, extending freely
into the snow. The different pressures encountered by the different obstacles is
quantitatively explained with a granular force model, assuming the formation of a
mobilized volume of snow granules extending from the obstacle upstream. The results
underscore the fundamental influence of the dimension of the sensor and the obstacle
on pressures. Our study highlights the difficulties that appear in the estimation of
forces in the gravitational flow regime, for which force amplification may be caused
by this mobilized volume at the scale of the whole structure, but also by plastic
wedges, or small dead zones, at the scale of the sensor mounted on a wider structure. |
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