{"id":{"repo_id":"vt","oai_identifier":"oai:vtechworks.lib.vt.edu:10919/91392"},"canonical_url":"https://search.dev.ndltd.org/etd/vt/oai:vtechworks.lib.vt.edu:10919/91392","repository":{"repo_id":"vt","name":"Virginia Tech","base_url":"https://vtechworks.lib.vt.edu/oai/request"},"display":{"title":"Site Response Characteristics of Compacted Gravel Fill in Iceland","abstract":"Local site conditions can greatly increase the intensity and character of earthquake shaking and, thus, the extent and type of structural damage. The removal and replacement of in-situ soils with compacted gravel-sized volcanic rock has been prevalent in the Icelandic foundation subgrade construction practice for decades, despite the unknown seismic site response characteristics of the fill (e.g., the predominant frequency and relative site amplification). To fill this knowledge gap, over 500 hours of microtremor measurements were made at six study sites located throughout the Reykjavík, Iceland, capital region. Measurements recorded at various construction stages (e.g., the in-situ or pre-excavation, post-excavation, intermediate grades, and final grade) reveal the change in site response characteristics before and after gravel fill placement. The data was analyzed using the horizontal-to-vertical spectral ratio (HVSR) technique over a bandwidth of 0.3 to 25 Hz. Generally, the pre-excavation condition had a predominant site frequency between 3.5 and 7 Hz with relative amplification between 3.8 and 3.9 times. The placement of gravel fill atop dense to very dense silty sand underlain by bedrock shifts the predominant frequency between 10 and 16 Hz with a relative peak amplification between 2.5 and 5.3 times, generally increasing with fill thickness. Fill underlain by undulating lava rock also results in a higher a predominant frequency between 9 and 10.5 Hz, but little change in relative site amplification occurred at these frequencies (between 0.95 and 1.2 times). This dissimilarity is due to the unique lava rock HVSR signatures which have large amplification values (between 2.6 to 3.9 times) throughout the high-band frequency range. Additional investigations of sites underlain by lava rock are required to draw stronger empirical trends. The data set produced by this study can serve as a useful tool for the local geotechnical and seismological communities to mitigate seismic risk for the capital region.","abstract_html":"Local site conditions can greatly increase the intensity and character of earthquake shaking and, thus, the extent and type of structural damage. The removal and replacement of in-situ soils with compacted gravel-sized volcanic rock has been prevalent in the Icelandic foundation subgrade construction practice for decades, despite the unknown seismic site response characteristics of the fill (e.g., the predominant frequency and relative site amplification). To fill this knowledge gap, over 500 hours of microtremor measurements were made at six study sites located throughout the Reykjavík, Iceland, capital region. Measurements recorded at various construction stages (e.g., the in-situ or pre-excavation, post-excavation, intermediate grades, and final grade) reveal the change in site response characteristics before and after gravel fill placement. The data was analyzed using the horizontal-to-vertical spectral ratio (HVSR) technique over a bandwidth of 0.3 to 25 Hz. Generally, the pre-excavation condition had a predominant site frequency between 3.5 and 7 Hz with relative amplification between 3.8 and 3.9 times. The placement of gravel fill atop dense to very dense silty sand underlain by bedrock shifts the predominant frequency between 10 and 16 Hz with a relative peak amplification between 2.5 and 5.3 times, generally increasing with fill thickness. Fill underlain by undulating lava rock also results in a higher a predominant frequency between 9 and 10.5 Hz, but little change in relative site amplification occurred at these frequencies (between 0.95 and 1.2 times). This dissimilarity is due to the unique lava rock HVSR signatures which have large amplification values (between 2.6 to 3.9 times) throughout the high-band frequency range. Additional investigations of sites underlain by lava rock are required to draw stronger empirical trends. The data set produced by this study can serve as a useful tool for the local geotechnical and seismological communities to mitigate seismic risk for the capital region.","abstract_has_math":false,"creators":["Kennedy, Thomas John"],"institution":"Virginia Tech","degree_name":"Master of Science","degree_level":"masters","degree_discipline":"Civil Engineering","degree_department":"Civil and Environmental Engineering","school":null,"contributors":[],"advisors":[],"committee_chairs":["Green, Russell A."],"committee_members":["Chapman, Martin C.","Rodriguez-Marek, Adrian"],"year":2019,"date_issued":"2019-07-09","date_published":"2019-07-09","updated_at":"2026-07-22T22:19:15Z","subjects":["H/V Spectral Ratio","Site Effects","Site Response Characteristics","Microtremor","Iceland"],"languages":[],"rights":["In Copyright"],"rights_urls":["http://rightsstatements.org/vocab/InC/1.0/"],"identifier_entries":[{"key":"dc:identifier.other","label":"Dc Identifier Other","values":["vt_gsexam:21399"],"render_values":[{"text":"vt_gsexam:21399","href":null,"code":true}]}]},"links":{"outbound_url":"http://hdl.handle.net/10919/91392","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.committeechair","label":"Committee Chair","values":["Green, Russell A."]},{"key":"dc:contributor.committeemember","label":"Committee Member","values":["Chapman, Martin C.","Rodriguez-Marek, Adrian"]},{"key":"dc:contributor.department","label":"Department","values":["Civil and Environmental Engineering"]},{"key":"dc:creator","label":"Author","values":["Kennedy, Thomas John"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2019-07-10T08:02:02Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2019-07-10T08:02:02Z"]},{"key":"dc:date.issued","label":"Date","values":["2019-07-09"]},{"key":"dc:publisher","label":"Institution","values":["Virginia Tech"]},{"key":"dc:type","label":"Dc Type","values":["Thesis"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Civil Engineering"]},{"key":"thesis:degree_level","label":"Degree Level","values":["masters"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Master of Science"]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["Virginia Polytechnic Institute and State University"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["H/V Spectral Ratio","Site Effects","Site Response Characteristics","Microtremor","Iceland"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:rights","label":"Dc Rights","values":["In Copyright"]},{"key":"dc:rights.uri","label":"Rights URI","values":["http://rightsstatements.org/vocab/InC/1.0/"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.other","label":"Dc Identifier Other","values":["vt_gsexam:21399"]},{"key":"dc:identifier.uri","label":"Identifier URI","values":["http://hdl.handle.net/10919/91392"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["Local site conditions can greatly increase the intensity and character of earthquake shaking and, thus, the extent and type of structural damage. The removal and replacement of in-situ soils with compacted gravel-sized volcanic rock has been prevalent in the Icelandic foundation subgrade construction practice for decades, despite the unknown seismic site response characteristics of the fill (e.g., the predominant frequency and relative site amplification). To fill this knowledge gap, over 500 hours of microtremor measurements were made at six study sites located throughout the Reykjavík, Iceland, capital region. Measurements recorded at various construction stages (e.g., the in-situ or pre-excavation, post-excavation, intermediate grades, and final grade) reveal the change in site response characteristics before and after gravel fill placement. The data was analyzed using the horizontal-to-vertical spectral ratio (HVSR) technique over a bandwidth of 0.3 to 25 Hz. Generally, the pre-excavation condition had a predominant site frequency between 3.5 and 7 Hz with relative amplification between 3.8 and 3.9 times. The placement of gravel fill atop dense to very dense silty sand underlain by bedrock shifts the predominant frequency between 10 and 16 Hz with a relative peak amplification between 2.5 and 5.3 times, generally increasing with fill thickness. Fill underlain by undulating lava rock also results in a higher a predominant frequency between 9 and 10.5 Hz, but little change in relative site amplification occurred at these frequencies (between 0.95 and 1.2 times). This dissimilarity is due to the unique lava rock HVSR signatures which have large amplification values (between 2.6 to 3.9 times) throughout the high-band frequency range. Additional investigations of sites underlain by lava rock are required to draw stronger empirical trends. The data set produced by this study can serve as a useful tool for the local geotechnical and seismological communities to mitigate seismic risk for the capital region."]},{"key":"dc:description.abstractgeneral","label":"General Abstract","values":["Problematic soil conditions can greatly increase the intensity and character of earthquake shaking and, thus, the extent and type of building damage. The removal of native soils and replacement with compacted gravel-sized fill has been the predominant building foundation subgrade construction method in Iceland for decades. The practice of removal and replacement is one of the oldest and conceptually simplest approaches of site improvement to reduce settlement and increase soil strength. However, the understanding of how compacted gravel fill responds to earthquake shaking was nonexistent in literature. To fill this knowledge gap, the response characteristics of compacted gravel fill were derived using the horizontal-to-vertical spectral ratio (HVSR) and standard spectral ratio (SSR) analysis techniques from a data set of over 500 hours of experimental in-field measurements. Measurements were recorded at various construction stages (e.g., pre-excavation or native soil, post-excavation, intermediate fill grades, and the final fill grade) to reveal the change in site response characteristics before and after gravel fill placement. The findings presented in this thesis can serve as useful information for the local geotechnical and seismological communities to mitigate seismic risk (e.g., the probability of building damage and/or loss of lives) of structures with compacted gravel fill subgrades in the Reykjavík, Iceland capital region."]},{"key":"dc:description.degree","label":"Dc Description Degree","values":["Master of Science"]},{"key":"dc:format.medium","label":"Dc Format Medium","values":["ETD"]},{"key":"dc:title","label":"Title","values":["Site Response Characteristics of Compacted Gravel Fill in Iceland"]}]}],"canonical_facts":{"dc:contributor.committeechair":["Green, Russell A."],"dc:contributor.committeemember":["Chapman, Martin C.","Rodriguez-Marek, Adrian"],"dc:contributor.department":["Civil and Environmental Engineering"],"dc:creator":["Kennedy, Thomas John"],"dc:date.accessioned":["2019-07-10T08:02:02Z"],"dc:date.available":["2019-07-10T08:02:02Z"],"dc:date.issued":["2019-07-09"],"dc:description.abstract":["Local site conditions can greatly increase the intensity and character of earthquake shaking and, thus, the extent and type of structural damage. The removal and replacement of in-situ soils with compacted gravel-sized volcanic rock has been prevalent in the Icelandic foundation subgrade construction practice for decades, despite the unknown seismic site response characteristics of the fill (e.g., the predominant frequency and relative site amplification). To fill this knowledge gap, over 500 hours of microtremor measurements were made at six study sites located throughout the Reykjavík, Iceland, capital region. Measurements recorded at various construction stages (e.g., the in-situ or pre-excavation, post-excavation, intermediate grades, and final grade) reveal the change in site response characteristics before and after gravel fill placement. The data was analyzed using the horizontal-to-vertical spectral ratio (HVSR) technique over a bandwidth of 0.3 to 25 Hz. Generally, the pre-excavation condition had a predominant site frequency between 3.5 and 7 Hz with relative amplification between 3.8 and 3.9 times. The placement of gravel fill atop dense to very dense silty sand underlain by bedrock shifts the predominant frequency between 10 and 16 Hz with a relative peak amplification between 2.5 and 5.3 times, generally increasing with fill thickness. Fill underlain by undulating lava rock also results in a higher a predominant frequency between 9 and 10.5 Hz, but little change in relative site amplification occurred at these frequencies (between 0.95 and 1.2 times). This dissimilarity is due to the unique lava rock HVSR signatures which have large amplification values (between 2.6 to 3.9 times) throughout the high-band frequency range. Additional investigations of sites underlain by lava rock are required to draw stronger empirical trends. The data set produced by this study can serve as a useful tool for the local geotechnical and seismological communities to mitigate seismic risk for the capital region."],"dc:description.abstractgeneral":["Problematic soil conditions can greatly increase the intensity and character of earthquake shaking and, thus, the extent and type of building damage. The removal of native soils and replacement with compacted gravel-sized fill has been the predominant building foundation subgrade construction method in Iceland for decades. The practice of removal and replacement is one of the oldest and conceptually simplest approaches of site improvement to reduce settlement and increase soil strength. However, the understanding of how compacted gravel fill responds to earthquake shaking was nonexistent in literature. To fill this knowledge gap, the response characteristics of compacted gravel fill were derived using the horizontal-to-vertical spectral ratio (HVSR) and standard spectral ratio (SSR) analysis techniques from a data set of over 500 hours of experimental in-field measurements. Measurements were recorded at various construction stages (e.g., pre-excavation or native soil, post-excavation, intermediate fill grades, and the final fill grade) to reveal the change in site response characteristics before and after gravel fill placement. The findings presented in this thesis can serve as useful information for the local geotechnical and seismological communities to mitigate seismic risk (e.g., the probability of building damage and/or loss of lives) of structures with compacted gravel fill subgrades in the Reykjavík, Iceland capital region."],"dc:description.degree":["Master of Science"],"dc:format.medium":["ETD"],"dc:identifier.other":["vt_gsexam:21399"],"dc:identifier.uri":["http://hdl.handle.net/10919/91392"],"dc:publisher":["Virginia Tech"],"dc:rights":["In Copyright"],"dc:rights.uri":["http://rightsstatements.org/vocab/InC/1.0/"],"dc:subject":["H/V Spectral Ratio","Site Effects","Site Response Characteristics","Microtremor","Iceland"],"dc:title":["Site Response Characteristics of Compacted Gravel Fill in Iceland"],"dc:type":["Thesis"],"thesis:degree_discipline":["Civil Engineering"],"thesis:degree_level":["masters"],"thesis:degree_name":["Master of Science"],"thesis:institution_name":["Virginia Polytechnic Institute and State University"]},"updated_at":"2026-07-22T22:19:15Z"}