Debris-flow deposition: Effects of pore-fluid pressure and friction concentrated at flow margins
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Abstract
Measurements of pore-fluid pressure and total bed-normal stress at the base of several ∼10 m3 experimental debris flows provide new insight into the process of debris-flow deposition. Pore-fluid pressures nearly sufficient to cause liquefaction were developed and maintained during flow mobilization and acceleration, persisted in debris-flow interiors during flow deceleration and deposition, and dissipated significantly only during postdepositional sediment consolidation. In contrast, leading edges of debris flows exhibited little or no positive pore-fluid pressure. Deposition therefore resulted from grain-contact friction and bed friction concentrated at flow margins. This finding contradicts models that invoke widespread decay of excess pore-fluid pressure, uniform viscoplastic yield strength, or pervasive grain-collision stresses to explain debris-flow deposition. Furthermore, the finding demonstrates that deposit thickness cannot be used to infer the strength of flowing debris.
| Publication type | Article |
|---|---|
| Publication Subtype | Journal Article |
| Title | Debris-flow deposition: Effects of pore-fluid pressure and friction concentrated at flow margins |
| Series title | Geological Society of America Bulletin |
| DOI | 10.1130/0016-7606(1999)111<1424:DFDEOP>2.3.CO;2 |
| Volume | 111 |
| Issue | 10 |
| Year Published | 1999 |
| Language | English |
| Publisher | Geological Society of America |
| Contributing office(s) | Cascades Volcano Observatory |
| Description | 11 p. |
| First page | 1424 |
| Last page | 1434 |