A laboratory-scale study on the role of mechanical vibrations in pore pressure generation in pyroclastic materials: implications for pyroclastic flows

Soria‐Hoyo, C.; Valverde, José Manuel García; Roche, Olivier

doi:10.1007/s00445-019-1271-3

Cited by 3 publications

(2 citation statements)

References 48 publications

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“…The sustained pore pressure, which may arise if the permeability is small owing to large amounts of fine ash, conterbalances the weight of grains and therefore reduces the internal friction. In this context, the fluidization process and related pore pressure effect have been studied intensively (e.g., Chédeville & Roche, 2014, 2018; Breard et al, 2018; Dufek & Manga, 2008; Girolami et al, 2008; Lube et al, 2019; Montserrat et al, 2012; Rowley et al, 2014; Roche et al, 2002; Smith et al, 2018; Soria‐Hoyo et al, 2019; Valverde & Soria‐Hoyo, 2015). At the laboratory scale, if the pore pressure is maintained long enough owing to slow pressure diffusion, the dynamics of a fluidized granular flow is similar to that of the well‐known dam‐break flow of pure fluids for which energy dissipation is weak (Roche et al, 2008).…”

Section: Earlier Workmentioning

confidence: 99%

Impact of Fluidized Granular Flows into Water: Implications for Tsunamis Generated by Pyroclastic Flows

2020

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Novel laboratory experiments of fluidized granular flows entering water are reported, for the purpose of investigating tsunamis generated by pyroclastic flows. Qualitatively, the impact of a fluidized granular flow into water leads to (i) an initial vertical granular jet over water, (ii) a leading and largest wave, and (iii) a turbulent mixing zone forming a turbidity current. The present study focuses on the leading wave features in the near‐field region, as a function of the mass flux per width qm and the volume per width υ of the flow, the maximum water depth Ho, and the slope angle θ of the inclined plane. The obtained waves are of Stokes and cnoidal types, for which the generation is mostly controlled by qm and υ. By contrast, Ho plays no role on the wave generation that occurs in the shallowest region. Moreover, a comparison between fluidized granular, dry (nonfluidized) granular, and water flows entering water is addressed under similar flow conditions. The dimensionless amplitude scales as A/Ho=f(ζ), where ζ=FrSMsinθ is a dimensionless parameter depending on the Froude number Fr, the relative slide thickness S, the relative mass M, and the slope angle θ. Data of fine fluidized granular, fine dry granular, and water flows collapse on a master curve, which implies that the nature of the flowing material is of lesser importance in the current setup. By contrast, coarse granular flows generate lower amplitude waves, which is attributed to the penetration of water into the porous granular medium.

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Section: Earlier Workmentioning

confidence: 99%

Impact of Fluidized Granular Flows into Water: Implications for Tsunamis Generated by Pyroclastic Flows

2020

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“…On the same principle, autofluidization occurs also in collapsing beds of fine particles released from some height above a solid surface, as demonstrated by numerical simulations Breard et al (2018) and laboratory experiments Chédeville and Roche (2018). Fine-grained mixtures can also be fluidized through mechanical vibrations that cause fluid-particle relative oscillations and related high pore fluid pressure, a phenomenon called acoustic streaming Valverde and Soria-Hoyo (2015); Soria-Hoyo et al (2019).…”

Section: Introductionmentioning

confidence: 94%

Influence of bottom roughness and ambient pressure conditions on the emplacement of experimental dam-break granular flows

et al. 2021

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Geophysical granular flows occur at the surface of the Earth and other planets with reduced atmospheric pressure. In this paper, we investigate the run-out of dam-break flows of particle-air mixtures with fine (d = 75µm) or coarse (d = 150µm) grains in a flume with different bottom roughness (δ) and vacuum degrees (P * ). Our results reveal an increase of the flow run-out as d/δ decreases for fine d = 75µm-particles, and run-out decreases with the dimensionless ambient pressure (P * ) for a given d/δ. In contrast, the run-out

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The contribution of experimental volcanology to the study of the physics of eruptive processes, and related scaling issues: A review

Roche

Carazzo

2019

Journal of Volcanology and Geothermal Research

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The experimental approach has become a major tool increasingly used by volcanologists in recent decades to investigate the physics of eruptive processes in complement to field and theoretical works. Researchers have developed various methodologies to study volcanic phenomena at reduced length scale. The works involve natural or analogue materials and their types range from first-order tests, to identify fundamental processes and make qualitative comparison with field observations, to more sophisticated experiments in which precise data obtained in a controlled environment can be used to validate outputs of theoretical models. Scaling is a central issue to ensure dynamic similarity between the small-scale experiments and the large-scale volcanic phenomena when natural conditions cannot be simulated due to inherent length scale difference and/or technical limitations. In this respect, dimensionless numbers are used to map physical regimes and to define scaling laws, which allow experimental results to be extrapolated to natural scale. This review presents the variety of experimental studies conducted to investigate subterraneous and aerial volcanic phenomena involving in particular fluid-particle mixtures. We focus on the major scaling issues and the physical regimes investigated, and we also highlight in a historical perspective some of the major advances achieved through experimental studies. Finally we conclude on some perspectives for future works.

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A laboratory-scale study on the role of mechanical vibrations in pore pressure generation in pyroclastic materials: implications for pyroclastic flows

Cited by 3 publications

References 48 publications

Impact of Fluidized Granular Flows into Water: Implications for Tsunamis Generated by Pyroclastic Flows

Impact of Fluidized Granular Flows into Water: Implications for Tsunamis Generated by Pyroclastic Flows

Influence of bottom roughness and ambient pressure conditions on the emplacement of experimental dam-break granular flows

The contribution of experimental volcanology to the study of the physics of eruptive processes, and related scaling issues: A review

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