Experimental study on the rheological behaviour of debris flow

Santolo, Anna Scotto di; Pellegrino, Andrea; Evangelista, Aldo

doi:10.5194/nhess-10-2507-2010

Cited by 49 publications

(27 citation statements)

References 18 publications

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“…We observe that, at equal total solid volumetric concentration, the adding of the solid fraction with a diameter less than 5 mm brings to a reduction of the characteristic resistance of the mixture regardless the material tested. Moreover, the addition of the fraction of particles with a diameter less than 5 mm corresponds to a solid volumetric concentration of coarse particles Φ g of about 8-10% of the entire total solid concentration, this result becomes consistent with several previous experimental observations ( [12]- [13]) and with the experimental results obtained through tests on the same coarsegrained mixtures with conventional measurement systems reported in [15]. Several studies have already demonstrated that the addition of coarse particles brings to an increase of the rheological characteristics of the mixture but, for relatively low solid volumetric concentration, a minimum depletion in fine particles fraction within the mixture does not seem to be sufficient to induce a increase of rheological parameters ( [12]- [13]- [14]- [15]).…”

Section: Results On Fine and Large Mixturessupporting

confidence: 92%

“…For mixtures and fluid containing large particle, the study of the influence of the grain size is more complicated. Experimental devises equipped with a large geometrical configurations are required and such apparatuses are few and not commercially developed [11]- [12]- [13]- [14]- [15]. The debris flow materials hereby considered presents a wide grain size distribution and a small content of fine particles.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

The Sphere Drag Rheometer: A New Instrument for Analysing Mud and Debris Flow Materials

Pellegrino¹,

Santolo²,

Schippa³

2016

Geomate

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ABSTRACT:The present study focused on novel rheometrical tool for the determination of the rheological behavior of large particle mixtures with particular interest in the application to granular materials involving in fast landslides as mud and debris flows. The main goal is the development of the Sphere Drag Rheometer (SDR), a home-made large-scale rheometer that allow to estimate the rheological properties of these mixtures considering particles up to 50 mm grain size. The SDR is composed of a sphere rigidly joined to a support that moves at constant velocity into the mixture. Compared to standard rheometer, the SDR uses much higher volume of mixtures of wider grain size distribution next to that in situ. Several pyroclastic soils collected from the source area of debris flows occurred in Campania region (Southern Italy) were analyzed. The paper reports the experimental results on fine particles mixtures, large particle mixtures, and their comparison. The experimental results on fine mixture are compared with those obtained by conventional rheometrical tools reported in previous papers.

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Section: Results On Fine and Large Mixturessupporting

confidence: 92%

Section: Introductionmentioning

confidence: 99%

The Sphere Drag Rheometer: A New Instrument for Analysing Mud and Debris Flow Materials

Pellegrino¹,

Santolo²,

Schippa³

2016

Geomate

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“…It is, however, established that local and large regional earthquakes can increase discharge at already-erupting mud volcanoes (e.g., Chigara and Tanaka, 1997; Mellors et al, 2007;Rukavickova and Hanzl, 2008;Bonini, 2009;Manga et al, 2009;Manga, 2010, 2012). All the mud volcanoes studied here responded to the 20 and 29 May 2012 Emilia earthquakes with epicenter 52-63 km and 42-52 km away from the mud volcanoes, respectively (section 2.2).…”

Section: Implications For Past Eruptionsmentioning

confidence: 99%

Large historical eruptions at subaerial mud volcanoes, Italy

Manga

Bonini

2012

Nat. Hazards Earth Syst. Sci.

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Abstract. Active mud volcanoes in the northern Apennines, Italy, currently have gentle eruptions. There are, however, historical accounts of violent eruptions and outbursts. Evidence for large past eruptions is also recorded by large decimeter rock clasts preserved in erupted mud. We measured the rheological properties of mud currently being erupted in order to evaluate the conditions needed to transport such large clasts to the surface. The mud is wellcharacterized by the Herschel-Bulkley model, with yield stresses between 4 and 8 Pa. Yield stresses of this magnitude can support the weight of particles with diameters up to several mm. At present, particles larger than this size are not being carried to the surface. The transport of larger clasts to the surface requires ascent speeds greater than their settling speed in the mud. We use a model for the settling of particles and rheological parameters from laboratory measurements to show that the eruption of large clasts requires ascent velocities > 1 m s −1 , at least three orders of magnitude greater than during the present, comparatively quiescent, activity. After regional earthquakes on 20 May and 29 May 2012, discharge also increased at locations where the stress changes produced by the earthquakes would have unclamped feeder dikes below the mud volcanoes. The magnitude of increased discharge, however, is less than that inferred from the large clasts. Both historical accounts and erupted deposits are consistent in recording episodic large eruptions.

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“…Flow behavior is partially characterized by the amount of volumetric concentration of a fluid matrix, C v , where V s and V w represent the respective sediment and pore water volumes in a given mixture [82].…”

Section: Calibration Of Rheological Valuesmentioning

confidence: 99%

Application of Sensitivity Analysis for Process Model Calibration of Natural Hazards

2018

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Sensitivity analysis (SA) describes how varying inputs to a model subsequently varies its outputs. Its inclusion can support the systematic calibration of numerical models to back-calculate intensity properties of past torrent events that would otherwise be difficult or impossible to collect during their occurrence. Sensitivity analysis for model calibration is assessed with the back-calculation of a known torrent event. In particular, FLO-2D, a cell-based numerical model, is used to simulate the 2005 debris flow event that occurred in Brienz, Switzerland. Under 4000 simulations were completed with ranges of physically reasonable parameter values. Model results were compared in 3-dimensions with both sediment deposition extents (x, y) and estimated deposition heights (z) from available post-event images. The comparisons highlighted that more accurate input and validation data, namely the flow behavior of hazardous processes and post-event deposition heights, are required to produce stronger agreements between simulated and observed results. Furthermore, the application of SA for model calibration supports systematic exploration of large parameter spaces characteristic of complex phenomena like natural hazard events. These findings demonstrated how important model input factors can be identified, which provide guidance for future data collection efforts to capture both the rheology and the spatial distribution of hazards more accurately.

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Experimental study on the rheological behaviour of debris flow

Cited by 49 publications

References 18 publications

The Sphere Drag Rheometer: A New Instrument for Analysing Mud and Debris Flow Materials

The Sphere Drag Rheometer: A New Instrument for Analysing Mud and Debris Flow Materials

Large historical eruptions at subaerial mud volcanoes, Italy

Application of Sensitivity Analysis for Process Model Calibration of Natural Hazards

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