Segregation and levee formation in geophysical mass flows and their feedback on runout distance
Lead Research Organisation:
University of Manchester
Department Name: Mathematics
Abstract
It is crucially important to be able to predict the distance to which a hazardous natural flow of rocky debris might travel; this is the flow runout distance. Runout distance has to be known for accurate assessment of the risks posed in populated areas by geophysical mass flows, such as snow slab avalanches, debris-flows and pyroclastic flows. In the high solids fraction regions of these flows the large and/or low-density particles commonly segregate to the surface, where the velocity is greatest, and are transported to the margins to form bouldery flow fronts. In pyroclastic and debris-flows the flow mobility results from high basal pore pressures that reduce the frictional resistance to motion. Since the pore pressure is dissipated much more rapidly amidst the coarse clasts than in the finer grained material, the bouldery margins experience much greater frictional resistance to motion than the flow interior. This can lead to frontal instabilities and surge waves on steep slopes. On shallow slopes, where the large/low density particles are able to come to rest, the flow front spontaneously organizes itself so that the more resistive bouldery material accumulates at the sides to form lateral levees. There are two mechanisms by which the large/low density particles can move to the side:- (i) they can be shoved en masse out of the way by the material behind or (ii) they can be over-run and recirculated by size/density segregation until they reach a stable position in the levee. Both mechanisms are active in most flows. Somewhat paradoxically, an increased resistance to motion in these bouldery perimeters can lead to much longer runout distances. This is because the levees form a channel that resists lateral spreading of the interior flow, in effect constraining the flow to push forward. This proposal aims to study the processes of segregation, flow mobility and levee formation, using a powerful combination of large-scale flume tests and field experiments, small-scale laboratory experiments and theoretical and computational modelling. This will significantly improve our ability to predict the motion and maximum runout distance of potentially hazardous geophysical mass flows, and will give sedimentologists an improved understanding of the parent flows that form deposits including coarse lobate terminations and levees.
Organisations
People |
ORCID iD |
Nico Gray (Principal Investigator) | |
Peter Kokelaar (Co-Investigator) |
Publications
Baker J
(2015)
A two-dimensional depth-averaged -rheology for dense granular avalanches
in Journal of Fluid Mechanics
Baker J
(2016)
Segregation-induced finger formation in granular free-surface flows
in Journal of Fluid Mechanics
Barker T
(2020)
Coupling rheology and segregation in granular flows
in Journal of Fluid Mechanics
Barker T
(2017)
Well-posed continuum equations for granular flow with compressibility and ยต(I)-rheology.
in Proceedings. Mathematical, physical, and engineering sciences
Barker T
(2015)
Well-posed and ill-posed behaviour of the -rheology for granular flow
in Journal of Fluid Mechanics
Chassagne R
(2020)
Discrete and continuum modelling of grain size segregation during bedload transport
in Journal of Fluid Mechanics
Cui X
(2013)
Gravity-driven granular free-surface flow around a circular cylinder
in Journal of Fluid Mechanics
Denissen I
(2019)
Bulbous head formation in bidisperse shallow granular flow over an inclined plane
in Journal of Fluid Mechanics
Edwards A
(2023)
Particle-size segregation in self-channelized granular flows
in Journal of Fluid Mechanics
Edwards A
(2021)
Erosion-deposition dynamics and long distance propagation of granular avalanches
in Journal of Fluid Mechanics
Edwards A
(2017)
Formation of levees, troughs and elevated channels by avalanches on erodible slopes
in Journal of Fluid Mechanics
Edwards A
(2014)
Erosion-deposition waves in shallow granular free-surface flows
in Journal of Fluid Mechanics
Edwards A
(2019)
Frictional hysteresis and particle deposition in granular free-surface flows
in Journal of Fluid Mechanics
Gajjar P
(2016)
Asymmetric breaking size-segregation waves in dense granular free-surface flows
in Journal of Fluid Mechanics
Gajjar P
(2021)
Size segregation of irregular granular materials captured by time-resolved 3D imaging.
in Scientific reports
Gajjar P
(2014)
Asymmetric flux models for particle-size segregation in granular avalanches
in Journal of Fluid Mechanics
Gray J
(2015)
Particle-size segregation in dense granular avalanches
in Comptes Rendus. Physique
Gray J
(2015)
Particle-size and -density segregation in granular free-surface flows
in Journal of Fluid Mechanics
Gray J
(2018)
Particle Segregation in Dense Granular Flows
in Annual Review of Fluid Mechanics
GRAY J
(2010)
Large particle segregation, transport and accumulation in granular free-surface flows - ERRATUM
in Journal of Fluid Mechanics
Gray J
(2014)
A depth-averaged -rheology for shallow granular free-surface flows
in Journal of Fluid Mechanics
GRAY J
(2010)
Large particle segregation, transport and accumulation in granular free-surface flows
in Journal of Fluid Mechanics
GRAY J
(2009)
Segregation, recirculation and deposition of coarse particles near two-dimensional avalanche fronts
in Journal of Fluid Mechanics
GRAY J
(2011)
Multi-component particle-size segregation in shallow granular avalanches
in Journal of Fluid Mechanics
Johnson C
(2012)
Grain-size segregation and levee formation in geophysical mass flows
in Journal of Geophysical Research: Earth Surface
JOHNSON C
(2011)
Granular jets and hydraulic jumps on an inclined plane
in Journal of Fluid Mechanics
Johnson C
(2010)
Granular jets and hydraulic jumps on an inclined plane
Kokelaar B
(2014)
Fine-grained linings of leveed channels facilitate runout of granular flows
in Earth and Planetary Science Letters
Kokelaar B
(2017)
Granular avalanches on the Moon: Mass-wasting conditions, processes, and features
in Journal of Geophysical Research: Planets
McIntyre M
(2010)
Evolution of a Mixing Zone in Granular Avalanches
in Applied Mathematics Research eXpress
Razis D
(2014)
Arrested coarsening of granular roll waves
in Physics of Fluids
Rocha F
(2019)
Self-channelisation and levee formation in monodisperse granular flows
in Journal of Fluid Mechanics
Russell A
(2019)
Retrogressive failure of a static granular layer on an inclined plane
in Journal of Fluid Mechanics
Schaeffer D
(2019)
Constitutive relations for compressible granular flow in the inertial regime
in Journal of Fluid Mechanics
SHEARER M
(2008)
Stable solutions of a scalar conservation law for particle-size segregation in dense granular avalanches
in European Journal of Applied Mathematics
THORNTON A
(2008)
Breaking size segregation waves and particle recirculation in granular avalanches
in Journal of Fluid Mechanics
Tregaskis C
(2021)
Subcritical and supercritical granular flow around an obstacle on a rough inclined plane
in Journal of Fluid Mechanics
Trewhela T
(2021)
An experimental scaling law for particle-size segregation in dense granular flows
in Journal of Fluid Mechanics
Trewhela T
(2021)
Large particle segregation in two-dimensional sheared granular flows
in Physical Review Fluids
Van Der Vaart K
(2015)
Underlying Asymmetry within Particle Size Segregation.
in Physical review letters
Van Der Vaart K
(2018)
Breaking size-segregation waves and mobility feedback in dense granular avalanches
in Granular Matter
Viroulet S
(2017)
Multiple solutions for granular flow over a smooth two-dimensional bump
in Journal of Fluid Mechanics
Viroulet S
(2021)
Modelling erosion and deposition in geophysical granular mass flows
in Europhysics News
Viroulet S
(2019)
Shedding dynamics and mass exchange by dry granular waves flowing over erodible beds
in Earth and Planetary Science Letters
Viroulet S
(2018)
The kinematics of bidisperse granular roll waves
in Journal of Fluid Mechanics
Wiederseiner S
(2011)
Experimental investigation into segregating granular flows down chutes
in Physics of Fluids
Woodhouse M
(2012)
Segregation-induced fingering instabilities in granular free-surface flows
in Journal of Fluid Mechanics
Description | Analysis of large scale flume experiments at the USGS flume have led to fundamental new insights into the way leveed channels form by the subtle feedback of bouldery flow fronts on the more mobile material behind. We have discovered that a simple coupling between particle-segregation and simple shallow water-like avalanche models for the bulk flow are ill-posed. This is a very interesting and suggests that the more details of the rheology are required in order to fully understand how highly fingered leveed channels form in geophysical mass flows |
Exploitation Route | The insights of both the segregation and rheology of granular flows have wide ranging importance in many fields. In particular there is an interesting crossover to industrial granular flows, where the same physics is active. Since 40% of all materials that are processes by industry are in granular form, there is a huge area to be explored here. |
Sectors | Agriculture, Food and Drink,Chemicals,Construction,Environment,Healthcare,Manufacturing, including Industrial Biotechology,Pharmaceuticals and Medical Biotechnology |
Description | Particle segregation is of enormous importance for industry and the research has directly led to an EPSRC Impact Acceleration Award (IAA) and subsequently a EPSRC Established Career Fellowship on taking what we have learnt in the geophysical context and applying it to basic unit operations in industry. |
First Year Of Impact | 2014 |
Sector | Agriculture, Food and Drink,Chemicals,Construction,Healthcare,Manufacturing, including Industrial Biotechology,Pharmaceuticals and Medical Biotechnology |
Impact Types | Economic |