Ifsttar PhD subject

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Title : Designing railways on grave-bitumen. Application to différent railway infrastructures. Full scale test under the dynamic system SYSIFE.

Main host Laboratory - Referent Advisor MAST - MIT  -  GABET Thomas      tél. : +33 240845684

Director of the main host Laboratory SEDRAN Thierry  -

Laboratory 2 - Referent Advisor MAST - LAMES  -  HORNYCH Pierre  -    -  tél. : +33 240845809

Laboratory 3 - Referent Advisor COSYS - SII  -  LE CAM Vincent  -    -  tél. : +33 240845778

PhD Speciality Mécanique, modélisation numérique, éléments finis, expérimentation échelle 1.

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

Main location Nantes

Doctoral affiliation UNIVERSITE DE NANTES

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

Planned PhD supervisor GABET Thomas  -  Université Gustave Eiffel  -  MAST - MIT

Planned PhD co-supervisor HORNYCH Pierre  -  Université Gustave Eiffel  -  MAST - LAMES

Planned financing Contrat doctoral  - Université Gustave Eiffel

Abstract

OBJECTIVE.
The objective of this project is to develop and adapting models aiming at designing, simulationg the structural behaviour of railway infrastructures on grave-bitumen and their evolution during time. This thesis takes into account the behaviours of ballast, asphalt concrete and soil.
FRAMEWORK.
railways lines on grave-bitumen are more and more used according to their numerous advantages from an environmental, practical, economical and maintainance point of view. However they need a peculiar attention, specifically in terms of strutural design, which strongly impacts its service time. Design affects fatigue characteristics and settlements that appear in the structure.
These design charcateristics are well controled in the domaain of roadway infrastructures. This project aims at taking inspiration of these design methods for using them to the particularities of loadings and trafic on railway infrastructures. Such methodologies are well controled for roadways, mainly thanks to numerous feedbacks from the field. Many parameters of the design methods could be fitted thanks to these feedbacks. In order to provide a first fit of the parameters adapted to the railway infrastructures, a full scale test is being to be performed under the dynamic system SYSIFE. SYSIFE allows to perform a dynamic load equivent to an axle passing on the track. The laboratory short track has to main advantages: it allows to completely control the loading, and to perform a complete instumentation of the track. Then the structure can be observed in standard situations, but it can be strongly sollicitated in oder to bring it to premature states of fatigue, cracks or settlements.
The key point of such a test is to provide the parameters for designing such structures, parameters necessarily provided by a feedback form the field.
THE PROJECT IN 4 POINTS.
DimGraB aims at designing ballasted railways on asphalt concrete layers. Four main actions will be performed:
- Structural simulations by FE methods in order to estimate the strains at the bottom of the asphalt concrete layer, using the viscoelastic characteristics of the material. Cast3m will be used for performing such simulations.
- Full scal test on a standard structure, aiming at observing the evolution of the fatigue characteristics of the railway structure under standardized railway loading
- Comparison between numerical and experimental results, in order to improve the quality of numerical simulations. The full scale test could then be submitted to extreme loadings in order to see what are the main processes of cracking/settlement/fatigue inside the asphalt concrete and inside the ballast.
- Extrapolating results to different kinds of infrastructures, with different plateforms, different loadings, in order to assess the potential of such techniques (secondary railway network, heavy hails, ...)

Keywords : Continuum Mechanics, modelling, bituminous mixtures, ballast, railways, railway infrastructures, viscoelasticity, viscoplasticity, finite elements method, experimentation, full scale test, SYSIFE, dynamic loadings.

Main host Laboratory - Referent Advisor	MAST - MIT - GABET Thomas tél. : +33 240845684
Director of the main host Laboratory	SEDRAN Thierry -
Laboratory 2 - Referent Advisor	MAST - LAMES - HORNYCH Pierre - - tél. : +33 240845809
Laboratory 3 - Referent Advisor	COSYS - SII - LE CAM Vincent - - tél. : +33 240845778
PhD Speciality	Mécanique, modélisation numérique, éléments finis, expérimentation échelle 1.
Axis of the performance contract	2 - COP2017 - More efficient and resilient infrastructure
Main location	Nantes
Doctoral affiliation	UNIVERSITE DE NANTES
PhD school	Sciences de l'Ingénierie et des Systèmes (SIS)
Planned PhD supervisor	GABET Thomas - Université Gustave Eiffel - MAST - MIT
Planned PhD co-supervisor	HORNYCH Pierre - Université Gustave Eiffel - MAST - LAMES
Planned financing	Contrat doctoral - Université Gustave Eiffel
Abstract OBJECTIVE. The objective of this project is to develop and adapting models aiming at designing, simulationg the structural behaviour of railway infrastructures on grave-bitumen and their evolution during time. This thesis takes into account the behaviours of ballast, asphalt concrete and soil. FRAMEWORK. railways lines on grave-bitumen are more and more used according to their numerous advantages from an environmental, practical, economical and maintainance point of view. However they need a peculiar attention, specifically in terms of strutural design, which strongly impacts its service time. Design affects fatigue characteristics and settlements that appear in the structure. These design charcateristics are well controled in the domaain of roadway infrastructures. This project aims at taking inspiration of these design methods for using them to the particularities of loadings and trafic on railway infrastructures. Such methodologies are well controled for roadways, mainly thanks to numerous feedbacks from the field. Many parameters of the design methods could be fitted thanks to these feedbacks. In order to provide a first fit of the parameters adapted to the railway infrastructures, a full scale test is being to be performed under the dynamic system SYSIFE. SYSIFE allows to perform a dynamic load equivent to an axle passing on the track. The laboratory short track has to main advantages: it allows to completely control the loading, and to perform a complete instumentation of the track. Then the structure can be observed in standard situations, but it can be strongly sollicitated in oder to bring it to premature states of fatigue, cracks or settlements. The key point of such a test is to provide the parameters for designing such structures, parameters necessarily provided by a feedback form the field. THE PROJECT IN 4 POINTS. DimGraB aims at designing ballasted railways on asphalt concrete layers. Four main actions will be performed: - Structural simulations by FE methods in order to estimate the strains at the bottom of the asphalt concrete layer, using the viscoelastic characteristics of the material. Cast3m will be used for performing such simulations. - Full scal test on a standard structure, aiming at observing the evolution of the fatigue characteristics of the railway structure under standardized railway loading - Comparison between numerical and experimental results, in order to improve the quality of numerical simulations. The full scale test could then be submitted to extreme loadings in order to see what are the main processes of cracking/settlement/fatigue inside the asphalt concrete and inside the ballast. - Extrapolating results to different kinds of infrastructures, with different plateforms, different loadings, in order to assess the potential of such techniques (secondary railway network, heavy hails, ...)
Keywords :	Continuum Mechanics, modelling, bituminous mixtures, ballast, railways, railway infrastructures, viscoelasticity, viscoplasticity, finite elements method, experimentation, full scale test, SYSIFE, dynamic loadings.

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