Journal ArticleDOI
Dry granular avalanche impact force on a rigid wall: Analytic shock solution versus discrete element simulations.
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TLDR
It is shown that the dead-zone dynamics and the mean force on the wall computed from DEM can be reproduced reasonably well by the analytic solution proposed over a wide range of slope angle of the incline, and that the assumption of a shock wave volume shrinking into a singular surface is questionable.Abstract:
The present paper investigates the mean impact force exerted by a granular mass flowing down an incline and impacting a rigid wall of semi-infinite height. First, this granular flow-wall interaction problem is modeled by numerical simulations based on the discrete element method (DEM). These DEM simulations allow computing the depth-averaged quantities-thickness, velocity, and density-of the incoming flow and the resulting mean force on the rigid wall. Second, that problem is described by a simple analytic solution based on a depth-averaged approach for a traveling compressible shock wave, whose volume is assumed to shrink into a singular surface, and which coexists with a dead zone. It is shown that the dead-zone dynamics and the mean force on the wall computed from DEM can be reproduced reasonably well by the analytic solution proposed over a wide range of slope angle of the incline. These results are obtained by feeding the analytic solution with the thickness, the depth-averaged velocity, and the density averaged over a certain distance along the incline rather than flow quantities taken at a singular section before the jump, thus showing that the assumption of a shock wave volume shrinking into a singular surface is questionable. The finite length of the traveling wave upstream of the grains piling against the wall must be considered. The sensitivity of the model prediction to that sampling length remains complicated, however, which highlights the need of further investigation about the properties and the internal structure of the propagating granular wave.read more
Citations
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Journal ArticleDOI
Numerical study of granular debris flow run-up against slit dams by discrete element method
TL;DR: In this article, an analytical model based on the momentum approach was derived to predict the run-up heights of granular debris flows against slit dams on slopes, which significantly affects the runup height.
Journal ArticleDOI
Design of active debris flow mitigation measures: a comprehensive analysis of existing impact models
TL;DR: A critical review of main existing models and equations treated in scientific literature is presented in this article, where the authors focus on the definition and the evaluation of the impacting load of debris flows on protection structures.
Journal ArticleDOI
Froude characterization for unsteady single-surge dry granular flows: impact pressure and runup height
TL;DR: The impact and pileup mechanisms of unsteady granular flows impacting a rigid barrier are governed by the Froude conditions as mentioned in this paper, where velocity and depth vary along the length of the flow.
Journal ArticleDOI
Impact force of granular flows on walls normal to the bottom: slow versus fast impact dynamics
TL;DR: The devastating effects of natural hazards due to the propagation of mass flows, such as landslides, debris flows, and avalanches, can be avoided, or at least reduced, by placing protective barrier as discussed by the authors.
Journal ArticleDOI
Impact dynamics of debris flow against rigid obstacle in laboratory experiments
TL;DR: In this article, the authors analyzed the kinetic and dynamic behavior of debris-flow impact with varying flow regime and found that the liquefaction ratio increases, resulting in a more fluid-like state of debris flow.
References
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Peter Cundall,Otto D. L. Strack +1 more
TL;DR: The distinct element method as mentioned in this paper is a numerical model capable of describing the mechanical behavior of assemblies of discs and spheres and is based on the use of an explicit numerical scheme in which the interaction of the particles is monitored contact by contact and the motion of the objects modelled particle by particle.
Journal ArticleDOI
A discrete numerical model for granular assemblies
Peter Cundall,Otto D. L. Strack +1 more
TL;DR: The distinct element method as mentioned in this paper is a numerical model capable of describing the mechanical behavior of assemblies of discs and spheres and is based on the use of an explicit numerical scheme in which the interaction of the particles is monitored contact by contact and the motion of the objects modelled particle by particle.
Journal ArticleDOI
Granular flow down an inclined plane: Bagnold scaling and rheology
Leonardo E. Silbert,Deniz Ertas,Gary S. Grest,Thomas C. Halsey,Dov Levine,Steven J. Plimpton +5 more
TL;DR: A systematic, large-scale simulation study of granular media in two and three dimensions, investigating the rheology of cohesionless granular particles in inclined plane geometries, finds that a steady-state flow regime exists in which the energy input from gravity balances that dissipated from friction and inelastic collisions is found.
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Shock waves, dead zones and particle-free regions in rapid granular free-surface flows
TL;DR: In this article, a simple hydraulic theory is generalized to model quasi-two-dimensional flows around obstacles and compared with laboratory experiments, which indicate that the theory is adequate to quantitatively describe the formation of normal shocks, oblique shocks, dead zones and granular vacua.
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The packing of particles
D. J. Cumberland,R. J. Crawford +1 more
TL;DR: The authors' interest in the subject was initially aroused by the question of whether there is an optimum particle size distribution which would maximise the packing density of particles -a question which has attracted the interest of scientists and engineers for centuries as discussed by the authors.
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