Premium
Debris flow rheology: Experimental analysis of fine‐grained slurries
Author(s) -
Major Jon J.,
Pierson Thomas C.
Publication year - 1992
Publication title -
water resources research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.863
H-Index - 217
eISSN - 1944-7973
pISSN - 0043-1397
DOI - 10.1029/91wr02834
Subject(s) - rheology , slurry , thixotropy , materials science , grain size , debris , bingham plastic , viscosity , particle size distribution , geotechnical engineering , debris flow , particle size , mineralogy , geology , composite material , oceanography , paleontology
The rheology of slurries consisting of ≤2‐mm sediment from a natural debris flow deposit was measured using a wide‐gap concentric‐cylinder viscometer. The influence of sediment concentration and size and distribution of grains on the bulk rheological behavior of the slurries was evaluated at concentrations ranging from 0.44 to 0.66. The slurries exhibit diverse rheological behavior. At shear rates above 5 s −1 the behavior approaches that of a Bingham material; below 5 s −1 , sand exerts more influence and slurry behavior deviates from the Bingham idealization. Sand grain interactions dominate the mechanical behavior when sand concentration exceeds 0.2; transient fluctuations in measured torque, time‐dependent decay of torque, and hysteresis effects are observed. Grain rubbing, interlocking, and collision cause changes in packing density, particle distribution, grain orientation, and formation and destruction of grain clusters, which may explain the observed behavior. Yield strength and plastic viscosity exhibit order‐of‐magnitude variation when sediment concentration changes as little as 2–4%. Owing to these complexities, it is unlikely that debris flows can be characterized by a single rheological model.