Mechanisms of large landslides

Erismann, Theodor H.

doi:10.1007/bf01241087

Cited by 191 publications

(98 citation statements)

References 14 publications

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“…In landslides and avalanches, the mechanism that supplies this energy is gravity; this energy is transferred into collisional energy and rubbing-like friction, and quickly dissipated. Savage (1989) quotes Erismann (1979), who has estimated the enormous energies involved in these events. "For instance, the prehistoric Flims landslide in Switzerland had a volume of about 1.2 x 10 6 m 3 , and probably took place over aperiod of a couple of minutes.…”

Section: Dilatancy Internal Friction Rate Dependence Of Stress Larmentioning

confidence: 99%

Avalanche Dynamics

Hutter¹

1996

Hydrology of Disasters

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ABSTRACT. This article reviews recent work on avalanche, landslide and rockfall dynamics. Two limiting cases of these flows exist, the so-called jIow avalanche, i. e., the dense gravity driven "laminar type flow" in which the role of the solid particles dominates, while that of the interstitial fluid is negligible -these flows are typical for most sturzstroms, debris flows, landslides, rockfalls and snow avalanches -and the less dense powder avalanche, i. e., the turbulent flow of air borne particles in a mixture, in which the role of the fluid dominates, while that of the particles is less significantthese flows are typical for density and turbidity currents such as dust clouds occuring in the desert, in pyroclastic volcanic eruptions, in submarine slope instabilities and in snow and ice avalanches. The latter application will be our focus. The state of the art in the description of both these phenomena is given. In the Introduction, after some historical remarks, we turn our attention to the characterization of the physical behaviour of the two limiting flow types and then discuss the laws of similitude and model theory relevant to modelling the flows in the laboratory. Flow avalanches, landslides and rockfalls are discussed first. It is argued that these flows can be described as a continuum consisting of a cohesionless granular material. Such materials exhibit dilatancy effects and large energy dissipation, and under quasistatic or dynamic shear deformation, they exhibit the property that the ratio of the shear stress to the normal stress on any interior plane is nearly constant, a fact reflected in the constancy of the internal angle of friction. In shear cell tests under quasistatic and rapid deformation at constant normal load, the internal stress is practically independent of the rate of shear; when the shear deformation is performed at constant volume however, the dependence of the stress on the rate of shear is quadratic. Three different flow regimes which partly interact can be distinguished: (i), Dry Coulomb, rubbing frictional behaviour, typical when particles are in contact and ride one over the other; (ii), collisional interactions when particles bounce against each other, contact is short, and the mean free path is of the order of the particle diameter; (iii), translational transport when the mean free path is large and particle concentrations correspondingly smalI. For the second and the third regime, statistical theories along the lines of the kinetic theory of a dense gas have been developed, but some of these show ill behaviour in steady chute flow problems. An adequate formulation must incorporate quasistatic and collisional contributions; the emerging theories, however, are patched together from alien components. Furthermore, simple chute flow problems turn out to be very difficult to solve. In the flow regime 317 V. P. Singh (ed.), Hydrology of Disasters

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Section: Dilatancy Internal Friction Rate Dependence Of Stress Larmentioning

confidence: 99%

Avalanche Dynamics

Hutter¹

1996

Hydrology of Disasters

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“…High pressure at the base of the flow can lead to a local melting and a drop of resistance to shear [Erismann, 1979]. Ground vibrations can restitute energy to the spreading flow [Melosh, 1979].…”

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confidence: 99%

Understanding how volume affects the mobility of dry debris flows

Staron¹,

Lajeunesse²

2009

Geophysical Research Letters

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[1] The prediction of the runout length L of large dry debris flows has long been the subject of a considerable research effort, primarily due to the obvious concern caused by their destructive power. One seemingly well established feature is the increase of the mobility M of a rock avalanche, defined as the ratio of the runout distance to the fall height, with its volume V. The physical nature of this lubrication mechanism remains however controversial. In this paper, we analyse field data and discrete numerical simulations of granular flows and demonstrate the geometrical origin of the apparent enhancement of the mobility with the volume. We evidence the intertwined role of volume and topography and show the existence of two contributions in the runout, defining two flow regimes: one dominated by sliding, in which the runout is independent of V, and another dominated by spreading, in which the runout is strongly dependent on V. In the light of these results, the search of a volume dependent lubrication mechanism appears to be an ill-posed problem. Citation: Staron, L., [Howard, 1973]. Beside an obvious concern for hazard assessment, rock avalanches are also efficient agents of erosion in active orogens, capable of moving large masses of material over kilometre-scale distances instantaneously [Hovius and Stark, 2006;Korup et al., 2007]. In spite of the sustained interest these dramatic natural events have raised in the scientific community, they still escape physical understanding [Iverson, 1997[Iverson, , 2003.[3] Among the various issues raised by these flows, the prediction of their runout length L (see Figure 2a, insert) keeps a first rank position, primarily due to the obvious concern caused by their destructive power. Surprisingly, they can travel over distances several times larger than the height H of the source topography [Dade and Huppert, 1998]. One seemingly established feature is the increase of the mobility M = L/H with the volume V of rock mobilized by the avalanche (Figure 2a). This positive correlation was first noted by Heim [1932]. Yet, the identification of lubrication mechanisms enhanced by volume remains a persisting and challenging issue [Legros, 2002, and references therein]. In this paper, we analyse both field data and discrete numerical simulations of granular flows, and show that the increase of M with V reflects a purely geometrical correlation. In the light of these results, the search for a volume dependent lubrication mechanism appears to be an ill-posed problem.[4] The conventional analysis of the dissipative properties of geological granular flows relies on the hypothesis, first put forward by Heim [1932] and prompted by an analogy with solid friction, that the whole of the initial potential energy of the mass is dissipated by the work of friction forces along the topography. Neglecting centripetal acceleration induced by the topography, and any other energy transfers in the system, we obtain:where m e is an effective friction coefficient quantifying the average macroscopic d...

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“…Such observations go back all the way to Heim's survey of the 1881 Elm slide [Heim, 1882[Heim, , 1932Hsü, 1978]. Other examples are the Karakoram slides [Hewitt, 1988[Hewitt, , 2002Hewitt et al, 2008], the Socompa slide [Wadge et al, 1995], the Köfels slide [Erismann, 1979], Madison Canyon [Hadley, 1964], Black Canyon, and El Capitan and Split Mountain slides [Yarnold and Lombard, 1989].) Campbell et al [1995] demonstrated that stratigraphy preservation is the result of a folding process during which the entire landslide is shearing, requiring a friction reduction mechanism that acts globally, not just in a basal layer.…”

Section: Modern Slides Have Diverse Compositionmentioning

confidence: 91%

Reply to comment by Iverson on “The reduction of friction in long runout landslides as an emergent phenomenon”

2016

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Here we address the comments by Iverson (2016) on our recent work concerning the reduction of friction in long runout landslides. Iverson (2016) questions the veracity of our models and suggests that high basal pore fluid pressure is the dominant mechanism reducing friction in long runout landslides. The main goal of our work was to elucidate the mechanism responsible for the apparent reduction of friction and long runout occurring in the landslide simulations of Campbell et al. (1995), which did not include an interstitial fluid. We found that the apparent reduction of friction in large slides could be explained by acoustic waves causing sliding to preferentially occur at pressures below the expected overburden, a mechanism reminiscent of acoustic fluidization. Such a mechanism is required to explain the long runout of dry landslides such as those on the Moon and other airless or waterless bodies. While our models provide no estimates of the effect of fluids on landslide runout, we have demonstrated a mechanism that increases runout distances that does not involve fluids.

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Mechanisms of large landslides

Cited by 191 publications

References 14 publications

Avalanche Dynamics

Avalanche Dynamics

Understanding how volume affects the mobility of dry debris flows

Reply to comment by Iverson on “The reduction of friction in long runout landslides as an emergent phenomenon”

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