Elements of an improved model of debris‐flow motion

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Abstract

A new depth‐averaged model of debris‐flow motion describes simultaneous evolution of flow velocity and depth, solid and fluid volume fractions, and pore‐fluid pressure. Non‐hydrostatic pore‐fluid pressure is produced by dilatancy, a state‐dependent property that links the depth‐averaged shear rate and volumetric strain rate of the granular phase. Pore‐pressure changes caused by shearing allow the model to exhibit rate‐dependent flow resistance, despite the fact that the basal shear traction involves only rate‐independent Coulomb friction. An analytical solution of simplified model equations shows that the onset of downslope motion can be accelerated or retarded by pore‐pressure change, contingent on whether dilatancy is positive or negative. A different analytical solution shows that such effects will likely be muted if downslope motion continues long enough, because dilatancy then evolves toward zero, and volume fractions and pore pressure concurrently evolve toward steady states.

Additional publication details

Publication type Conference Paper
Publication Subtype Conference Paper
Title Elements of an improved model of debris‐flow motion
DOI 10.1063/1.3180101
Volume 1145
Year Published 2009
Language English
Publisher American Institute of Physics
Contributing office(s) Volcano Science Center
Description 7 p.
Larger Work Type Conference Paper
Larger Work Title Powders and Grains 2009: Proceedings of the 6th International Conference on Micromechanics of Granular Media
First page 9
Last page 16
Conference Title 6th International Conference on Micromechanics of Granular Media
Conference Location Golden, Colorado
Conference Date July 13-17 2009
Online Only (Y/N) N
Additional Online Files (Y/N) N