EROSION PROCESSES IN GRANULAR FLOWS
Gravitational instabilities such as avalanches and pyroclastic flows are a major hazard in seismic, mountainous and coastal areas.
A burning issue is to explain the great mobility of these phenomena. Recent studies [e.g. Mangeney et al., 2010] showed that erosion and entrainment of previous deposits by the flow plays a crucial role.
Granular columns were released in an inclined channel covered (or not) by an erodible bed of same material.
OBJECTIVE: observe and quantify the influence of the column's volume, aspect ratio (i.e. height over length), shape ; channel slope angle, width and erodible bed's thickness and compaction on the granular flow deposit and dynamics.
A burning issue is to explain the great mobility of these phenomena. Recent studies [e.g. Mangeney et al., 2010] showed that erosion and entrainment of previous deposits by the flow plays a crucial role.
Granular columns were released in an inclined channel covered (or not) by an erodible bed of same material.
OBJECTIVE: observe and quantify the influence of the column's volume, aspect ratio (i.e. height over length), shape ; channel slope angle, width and erodible bed's thickness and compaction on the granular flow deposit and dynamics.
This video shows an example of granular flow over an erodible bed:
For high slope angles (> 20°) the entrainment of the erodible bed by the granular flow is clearly visible on this video: erosion waves appear at the interface between the flow (white) and the bed (black):
KEY REFERENCES
Farin, M., A. Mangeney, and O. Roche (2013). Fundamental changes of granular flow dynamics, deposition,
and erosion processes at high slope angles: Insights from laboratory experiments, J. Geophys. Res. Earth Surf., 119, doi:10.1002/2013JF002750 (download the pdf)
Mangeney, A., Roche, O., Hungr, O., Mangold, Faccanoni, G., and Lucas, A. , 2010. Erosion and mobility in granular collapse over sloping beds, J. GEOPHYS. RES. - EARTH SURFACE, 115, F03040.
Farin, M., A. Mangeney, and O. Roche (2013). Fundamental changes of granular flow dynamics, deposition,
and erosion processes at high slope angles: Insights from laboratory experiments, J. Geophys. Res. Earth Surf., 119, doi:10.1002/2013JF002750 (download the pdf)
Mangeney, A., Roche, O., Hungr, O., Mangold, Faccanoni, G., and Lucas, A. , 2010. Erosion and mobility in granular collapse over sloping beds, J. GEOPHYS. RES. - EARTH SURFACE, 115, F03040.