Computing granular avalanches and landslides

Abstract

Geophysical mass flows-debris flows, volcanic avalanches, landslides-are often initiated by volcanic activity. These flows can contain O(10 6-10 7) m 3 or more of material, typically soil and rock fragments that might range from centimeters to meters in size, are typically O(10 m) deep, and can run out over distances of tens of kilometers. This vast range of scales, the rheology of the geological material under consideration, and the presence of interstitial fluid in the moving mass, all make for a complicated modeling and computing problem. Although we lack a full understanding of how mass flows are initiated, there is a growing body of computational and modeling research whose goal is to understand the flow processes, once the motion of a geologic mass of material is initiated. This paper describes one effort to develop a tool set for simulations of geophysical mass flows. We present a computing environment that incorporates topographical data in order to generate a numerical grid on which a parallel, adaptive mesh Godunov solver can simulate model systems of equations that contain no interstitial fluid. The computational solver is flexible, and can be changed to allow for more complex material models, as warranted.

Debris flows: Experiments and modelling

“…(21) has been carefully constructed to ensure that when it is summed over all constituents it yields the bulk incompressibility condition ∇ · u = 0. This condition and the lithostatic pressure distribution (8), are the key assumptions underlying most models for granular avalanches and geophysical mass flows (e.g., [1,20,21,30,[78][79][80][81][82][83][84]). The bulk threedimensional velocity field u may be reconstructed from depth-averaged avalanche models (e.g., [58]), or it may also be computed directly using the μ(I) rheology [85].…”

“…J.M.N.T. Gray et al / C. R. Physique 16 (2015) [73][74][75][76][77][78][79][80][81][82][83][84][85] jacente de grains statiques ou en déplacement lent. La combinaison de la ségrégation et des changements de phase solide-fluide granulaire crée des motifs complexes dans les dépôts résultants, mais la compréhension complète de ces effets est pour le moment hors de portée.…”

Aplicación de modelos numéricos de "aguas someras" para el análisis de peligros de flujos volcánicos: El caso de Titan2D y volcán Turrialba (Costa Rica)

“…In terms of strong internal shocks, the full Coulomb models are able to reproduce complex features of granular flows (Gray et al, 2003), such as the shocks themselves and "dead zones" where particles come to rest and accumulate. Comparisons of numerical implementations of Coulomb models with natural pyroclastic flows have also shown some success (e.g., Pitman et al, 2003;Rupp et al, 2006;Macias et al, 2008;Ogburn, 2008;Ogburn et al, in press;Charbonnier & Gertisser, 2009, 2012.…”

“…It combines numerical simulations of a flow with digital elevation data of natural terrain supported by a Geographical Information System (GIS) interface. The conservation equations for mass and momentum are solved with a Coulomb-type friction term for the interactions between the grains of the media and between the granular material and the basal surface (Savage & Hutter, 1989;Pitman et al, 2003).…”

“…The Titan2D computer program (Pitman et al, 2003;Patra et al, 2005) was designed by the Geophysical Mass Flow Modeling Group at University at Buffalo, USA, to simulate dry granular avalanches over digital representations of natural terrain. The program is built on a depth-averaged model for an incompressible Coulomb continuum, a "shallow water" granular flow, based on the work of Savage & Hutter (1989), Iverson (1997), , and Mangeney-Castelnau et al (2002).…”