Liquefaction and Reliquefaction Characteristics of Compacted Slightly-Weathered Heterogeneous Tephras

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dc.contributor.authorSood S
dc.contributor.authorChiaro, Gabriele
dc.contributor.authorWilson T
dc.contributor.authorStringer M
dc.date.accessioned2024-08-12T00:26:15Z
dc.date.available2024-08-12T00:26:15Z
dc.date.issued2024
dc.description.abstractTephras of slightly-weathered nature are essentially silty-sand deposits with no to low plasticity. They can constitute variable gradations and geochemical compositions depending upon the type and extent of weathering of particles and minerals. Case histories of liquefaction events suggest that such sand and silty-sand deposits can liquefy and reliquefy by a succeeding seismic event. However, the liquefaction and reliquefaction characteristics of different compacted tephras for backfilling usage have not been largely investigated. This paper presents the results of a series of undrained cyclic triaxial tests on specimens of three tephras(two rhyolitic and one basalt-andesitic) sourced from the North Island of New Zealand. Specimens are compacted at 90 % degree of compaction, isotropically consolidated under 100 kPa effective confining stress and then subjected to the first cyclic loading phase until liquefaction is achieved. Following liquefaction, specimens are reconsolidated and reliquefied. The test results showed an increase in the degree of compaction after reconsolidation for the compacted tephra specimens. However, a non-unified change in the liquefaction resistance is observed for the tephra specimens, which is dependent on their geochemical composition (or degree of weathering value) affecting the stress level (CSR) required. The elementally identical rhyolitic Kaharoa ashes (White Kaharoa Ash – WKA – and Golden Kaharoa Ash – GKA) exhibited a decrease in the liquefaction resistance following the first series of loading cycles. Despite a similar reliquefaction response, the liquefaction resistance of GKA was significantly lower in comparison to WKA tephra due to its more weathered nature. On the other hand, the basalt andesitic Maungataketake Ash (MA) tephra, being the most weathered out of the three tephras, showcased an opposite trend of increase in cyclic resistance after initial liquefaction.
dc.identifier.citationSood S, Chiaro G, Wilson T, Stringer M (2024). Liquefaction and Reliquefaction Characteristics of Compacted Slightly-Weathered Heterogeneous Tephras. Osaka, Japan: 8th International Conference on Earthquake Geotechnical Engineering. 07/05/2024-10/05/2024. Japanese Geotechnical Society Special Publication. 10. 32. 1200-1205.
dc.identifier.doihttp://doi.org/10.3208/jgssp.v10.OS-21-01
dc.identifier.issn2188-8027
dc.identifier.urihttps://hdl.handle.net/10092/107277
dc.publisherThe Japanese Geotechnical Society
dc.rightsAll rights reserved unless otherwise stated
dc.rights.urihttp://hdl.handle.net/10092/17651
dc.subjectweathered
dc.subjectcompacted
dc.subjecttephra
dc.subjectliquefaction
dc.subjectreliquefaction
dc.subject.anzsrc40 - Engineering::4005 - Civil engineering::400502 - Civil geotechnical engineering
dc.subject.anzsrc40 - Engineering::4005 - Civil engineering::400506 - Earthquake engineering
dc.subject.anzsrc37 - Earth sciences::3705 - Geology::370512 - Volcanology
dc.titleLiquefaction and Reliquefaction Characteristics of Compacted Slightly-Weathered Heterogeneous Tephras
dc.typeConference Contributions - Published
uc.collegeFaculty of Engineering
uc.departmentCivil and Natural Resources Engineering
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