Ifsttar PhD subject

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Title : Effect of non-plastic fines on the liquefaction-induced embankment failure during earthquake: Centrifuge and numerical modeling

Main host Laboratory - Referent Advisor GERS - CG  -  LI Zheng

Director of the main host Laboratory BLANC Matthieu  -

PhD Speciality Ingénierie géotechnique; Mécanique

Axis of the performance contract 2 - COP2017 - More efficient and resilient infrastructure

Main location Nantes

Doctoral affiliation ECOLE CENTRALE NANTES

PhD school Sciences de l'Ingénierie et des Systèmes (SIS)

Planned PhD supervisor THOREL Luc  -  Université Gustave Eiffel  -  GERS - CG

Planned financing Contrat doctoral  - Ifsttar

Abstract

Investigating the behavior of embankment and ensuring its safety in liquefiable zones is an important topic, as is understanding the effects of fines on soil liquefaction, which remain unclear and contradictory. Therefore, the goal is to study the behavior of the embankment resting on the liquefiable sand ground taking into account the presence of non-plastic fines. The technical approach combines experimental and numerical methods. A series of centrifuge model tests, reproducing an embankment constructed on liquefiable soil, has been conducted. The liquefiable soil in these models was prepared by a mixture of sand and non-plastic fines (HN31-C500) with varying fine contents (0%, 5%, and 10%). In parallel, a numerical simulation using finite element analysis was carried out using the OpenSees simulation code and PM4Sand constitutive model. The experimental and numerical studies show that: 1) liquefaction occurred under the free surface rather than under the embankment, and 2) the embankment experienced settlement at the crest and lateral displacements at the base. Furthermore, they demonstrate that the presence of non-plastic fine particles results in: 1) increased soil resistance and reduced liquefaction intensity, and 2) decreased deformation intensity of the embankment.

Keywords : Centrifuge modelling, Numerical modelling, Liquefaction, Embankment, Non-plastic fines

Main host Laboratory - Referent Advisor	GERS - CG - LI Zheng
Director of the main host Laboratory	BLANC Matthieu -
PhD Speciality	Ingénierie géotechnique; Mécanique
Axis of the performance contract	2 - COP2017 - More efficient and resilient infrastructure
Main location	Nantes
Doctoral affiliation	ECOLE CENTRALE NANTES
PhD school	Sciences de l'Ingénierie et des Systèmes (SIS)
Planned PhD supervisor	THOREL Luc - Université Gustave Eiffel - GERS - CG
Planned financing	Contrat doctoral - Ifsttar
Abstract Investigating the behavior of embankment and ensuring its safety in liquefiable zones is an important topic, as is understanding the effects of fines on soil liquefaction, which remain unclear and contradictory. Therefore, the goal is to study the behavior of the embankment resting on the liquefiable sand ground taking into account the presence of non-plastic fines. The technical approach combines experimental and numerical methods. A series of centrifuge model tests, reproducing an embankment constructed on liquefiable soil, has been conducted. The liquefiable soil in these models was prepared by a mixture of sand and non-plastic fines (HN31-C500) with varying fine contents (0%, 5%, and 10%). In parallel, a numerical simulation using finite element analysis was carried out using the OpenSees simulation code and PM4Sand constitutive model. The experimental and numerical studies show that: 1) liquefaction occurred under the free surface rather than under the embankment, and 2) the embankment experienced settlement at the crest and lateral displacements at the base. Furthermore, they demonstrate that the presence of non-plastic fine particles results in: 1) increased soil resistance and reduced liquefaction intensity, and 2) decreased deformation intensity of the embankment.
Keywords :	Centrifuge modelling, Numerical modelling, Liquefaction, Embankment, Non-plastic fines

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