Plasticity, Flow Liquefaction, and Cyclic Mobility in Liquefiable Soils with Low to Moderate Plasticity

Over the past several decades, extensive research has advanced the understanding of liquefaction in clean sands and sand–silt mixtures under seismic loading. However, the influence of plastic (i.e., clayey) fines on the liquefaction behavior of sandy soils remains less well understood. This study in...

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Main Authors: Carmine P. Polito, James R. Martin
Format: Article
Language:English
Published: MDPI AG 2025-06-01
Series:CivilEng
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Online Access:https://www.mdpi.com/2673-4109/6/2/31
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author Carmine P. Polito
James R. Martin
author_facet Carmine P. Polito
James R. Martin
author_sort Carmine P. Polito
collection DOAJ
description Over the past several decades, extensive research has advanced the understanding of liquefaction in clean sands and sand–silt mixtures under seismic loading. However, the influence of plastic (i.e., clayey) fines on the liquefaction behavior of sandy soils remains less well understood. This study investigates how the quantity and plasticity of fines affect both the susceptibility to liquefaction and the resulting failure mode. A series of stress-controlled cyclic triaxial tests were conducted on sand specimens containing varying proportions of non-plastic silt, kaolinite, and bentonite. Specimens were prepared at a constant relative density with fines content ranging from 0% to 37%. Two liquefaction modes were examined: flow liquefaction, characterized by sudden and large strains under undrained conditions, and cyclic mobility, which involves gradual strain accumulation without complete strength loss. The results revealed a clear relationship between soil plasticity and liquefaction mode. Specimens containing non-plastic fines or fines with a liquid limit (LL) below 20% and a plasticity index (PI) of 0 exhibited flow liquefaction. In contrast, specimens with LL > 20% and PI ≥ 7% consistently displayed cyclic mobility behavior. These findings help reconcile the apparent contradiction between laboratory studies, which often show increased liquefaction susceptibility with plastic fines, and field observations, where clayey soils frequently appear non-liquefiable. The study emphasizes the critical role of plasticity in determining liquefaction type, providing essential insight for seismic risk assessments and design practices involving fine-containing sandy soils.
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spelling doaj-art-84e9bbf253174d45aea5be5c90f2ffd62025-08-20T03:26:21ZengMDPI AGCivilEng2673-41092025-06-01623110.3390/civileng6020031Plasticity, Flow Liquefaction, and Cyclic Mobility in Liquefiable Soils with Low to Moderate PlasticityCarmine P. Polito0James R. Martin1Department of Civil and Environmental Engineering, Valparaiso University, Valparaiso, IN 46383, USANorth Carolina Agricultural and Technical State University, Greensboro, NC 27411, USAOver the past several decades, extensive research has advanced the understanding of liquefaction in clean sands and sand–silt mixtures under seismic loading. However, the influence of plastic (i.e., clayey) fines on the liquefaction behavior of sandy soils remains less well understood. This study investigates how the quantity and plasticity of fines affect both the susceptibility to liquefaction and the resulting failure mode. A series of stress-controlled cyclic triaxial tests were conducted on sand specimens containing varying proportions of non-plastic silt, kaolinite, and bentonite. Specimens were prepared at a constant relative density with fines content ranging from 0% to 37%. Two liquefaction modes were examined: flow liquefaction, characterized by sudden and large strains under undrained conditions, and cyclic mobility, which involves gradual strain accumulation without complete strength loss. The results revealed a clear relationship between soil plasticity and liquefaction mode. Specimens containing non-plastic fines or fines with a liquid limit (LL) below 20% and a plasticity index (PI) of 0 exhibited flow liquefaction. In contrast, specimens with LL > 20% and PI ≥ 7% consistently displayed cyclic mobility behavior. These findings help reconcile the apparent contradiction between laboratory studies, which often show increased liquefaction susceptibility with plastic fines, and field observations, where clayey soils frequently appear non-liquefiable. The study emphasizes the critical role of plasticity in determining liquefaction type, providing essential insight for seismic risk assessments and design practices involving fine-containing sandy soils.https://www.mdpi.com/2673-4109/6/2/31liquefactionflow liquefactioncyclic mobilityliquid limitplasticity indexplasticity
spellingShingle Carmine P. Polito
James R. Martin
Plasticity, Flow Liquefaction, and Cyclic Mobility in Liquefiable Soils with Low to Moderate Plasticity
CivilEng
liquefaction
flow liquefaction
cyclic mobility
liquid limit
plasticity index
plasticity
title Plasticity, Flow Liquefaction, and Cyclic Mobility in Liquefiable Soils with Low to Moderate Plasticity
title_full Plasticity, Flow Liquefaction, and Cyclic Mobility in Liquefiable Soils with Low to Moderate Plasticity
title_fullStr Plasticity, Flow Liquefaction, and Cyclic Mobility in Liquefiable Soils with Low to Moderate Plasticity
title_full_unstemmed Plasticity, Flow Liquefaction, and Cyclic Mobility in Liquefiable Soils with Low to Moderate Plasticity
title_short Plasticity, Flow Liquefaction, and Cyclic Mobility in Liquefiable Soils with Low to Moderate Plasticity
title_sort plasticity flow liquefaction and cyclic mobility in liquefiable soils with low to moderate plasticity
topic liquefaction
flow liquefaction
cyclic mobility
liquid limit
plasticity index
plasticity
url https://www.mdpi.com/2673-4109/6/2/31
work_keys_str_mv AT carmineppolito plasticityflowliquefactionandcyclicmobilityinliquefiablesoilswithlowtomoderateplasticity
AT jamesrmartin plasticityflowliquefactionandcyclicmobilityinliquefiablesoilswithlowtomoderateplasticity