Please use this identifier to cite or link to this item: http://hdl.handle.net/2122/8792
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dc.contributor.authorallCagnoli, B.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italiaen
dc.contributor.authorallRomano, G. P.; Ingegneria, La Sapienzaen
dc.date.accessioned2013-11-18T13:42:55Zen
dc.date.available2013-11-18T13:42:55Zen
dc.date.issued2013en
dc.identifier.urihttp://hdl.handle.net/2122/8792en
dc.description.abstractIn this paper, we illustrate laboratory experiments whose purpose is to study the vertical segregations that are commonly observed in deposits of dense geophysical flows (such as pyroclastic flows and rock avalanches). In these experiments, we use rock cuboids with 5 mm long edges as matrix and rock cuboids with 2 cm long edges as segregating clasts. A rotating disk is used to apply frictional stresses at the base of the granular masses. In our experiments, segregating cuboids with density smaller than or equal to that of the matrix particles rise whereas segregating cuboidswith density larger than that of the matrix particles sink. The granular flows are imaged through the glass container of the experimental apparatus by a high-speed video camera at 2000 fps. By means of particle image velocimetry analysis of the movies, we study the vertical gradient of particle agitation that exists within the granular flows where agitation increases downward because of the interaction with the subsurface asperities. The high-speed movies show that it is the particle agitation within the flows that exerts an upward force and that, when this force is larger than theweight of the segregating clast, the clast riseswhereas, when it is smaller, the clast sinks. The most important result in our set of experiments is that the threshold which separates the values of density of the segregating clasts that segregate upward and the values of density of the segregating clasts that segregate downward is larger than the density of the matrix particles. This explains the upward segregation of dense lithics that is frequently observed in deposits of geophysical flows. This upward segregation is due to the fact that the resultant of the collisions exerted by the matrix particles is a force strong enough to push upward also dense and heavy fragments.en
dc.language.isoEnglishen
dc.publisher.nameElsevier Science Limiteden
dc.relation.ispartofJournal of volcanology and geothermal researchen
dc.relation.ispartofseries/265 (2013)en
dc.subjectpyroclastic flowsen
dc.subjectvertical segregationen
dc.subjectrock avalanchesen
dc.titleVertical segregations in flows of angular rock fragments: Experimental simulations of the agitation gradient within dense geophysical flowsen
dc.typearticleen
dc.description.statusPublisheden
dc.type.QualityControlPeer-revieweden
dc.description.pagenumber52-59en
dc.subject.INGV04. Solid Earth::04.08. Volcanology::04.08.02. Experimental volcanismen
dc.identifier.doi10.1016/j.jvolgeores.2013.08.017en
dc.description.obiettivoSpecifico3.6. Fisica del vulcanismoen
dc.description.journalTypeJCR Journalen
dc.description.fulltextrestricteden
dc.relation.issn0377-0273en
dc.relation.eissn1872-6097en
dc.contributor.authorCagnoli, B.en
dc.contributor.authorRomano, G. P.en
dc.contributor.departmentIstituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italiaen
dc.contributor.departmentIngegneria, La Sapienzaen
item.openairetypearticle-
item.cerifentitytypePublications-
item.languageiso639-1en-
item.grantfulltextrestricted-
item.openairecristypehttp://purl.org/coar/resource_type/c_18cf-
item.fulltextWith Fulltext-
crisitem.author.deptIstituto Nazionale di Geofisica e Vulcanologia (INGV), Sezione Bologna, Bologna, Italia-
crisitem.author.deptUniversità degli Studi di Bari-
crisitem.author.orcid0000-0003-3263-5345-
crisitem.author.parentorgIstituto Nazionale di Geofisica e Vulcanologia-
crisitem.classification.parent04. Solid Earth-
crisitem.department.parentorgIstituto Nazionale di Geofisica e Vulcanologia-
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