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Valid debris-flow models must avoid hot starts

September 30, 2019

Debris-flow experiments and models commonly use “hot-start” initial conditions in which downslope motion begins when a large force imbalance is abruptly imposed. By contrast, initiation of natural debris flows almost invariably results from small perturbations of static force balances that apply to debris masses poised in steep channels or on steep slopes. Models that neglect these static balances may violate physical law. Here we assess how the effects of hot starts are manifested in physical experiments, analytical dam-break models, and numerical models in which frictional resistance is too small to satisfy static force balances in debris-flow source areas. We then outline a numerical modeling framework that avoids use of hot starts. In this framework an initial static force balance is gradually perturbed by increasing pore-fluid pressure that may trigger the onset of debris motion. Subsequent increases in pore-fluid pressure, driven by debris motion, may then reduce the debris frictional strength, leading to high flow mobility.

Citation Information

Publication Year 2019
Title Valid debris-flow models must avoid hot starts
DOI 10.25676/11124/173051
Authors Richard M. Iverson, David L. George
Publication Type Conference Paper
Publication Subtype Conference Paper
Index ID 70213104
Record Source USGS Publications Warehouse
USGS Organization Volcano Science Center

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