Field observations of basal forces and fluid pore pressure in a debris flow
- Using results from an 8 m2 instrumented force plate we describe field measurements of normal and shear stresses, and fluid pore pressure for a debris flow. The flow depth increased from 0.1 to 1 m within the first 12 s of flow front arrival, remained relatively constant until 100 s, and then gradually decreased to 0.5 m by 600 s. Normal and shear stresses and pore fluid pressure varied in-phase with the flow depth. Calculated bulk densities are ρb = 2000–2250 kg m−3 for the bulk flow and ρf = 1600–1750 kg m−3 for the fluid phase. The ratio of effective normal stress to shear stress yields a Coulomb basal friction angle of ϕ = 26° at the flow front. We did not find a strong correlation between the degree of agitation in the flow, estimated using the signal from a geophone on the force plate, and an assumed dynamic pore fluid pressure. Our data support the idea that excess pore-fluid pressures are long lived in debris flows and therefore contribute to their unusual mobility.
Author: | Brian W. McArdell, Perry Bartelt, Julia KowalskiORCiD |
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ISBN: | 0094-8276 |
Parent Title (English): | Geophysical Research Letters (GRL) |
Document Type: | Article |
Language: | English |
Year of Completion: | 2007 |
Tag: | debris flow |
Volume: | 34 |
Issue: | 7 |
Link: | http://dx.doi.org/10.1029/2006GL029183 |
Zugriffsart: | bezahl |
Institutes: | FH Aachen / Fachbereich Luft- und Raumfahrttechnik |