Ifsttar PhD subject

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Title : Prediction of flood defense structures stability for Early Warning System (EWS) and improvement of levees resilience

Main host Laboratory - Referent Advisor GERS - SRO  -  REIFFSTECK Philippe      tél. : +33 181668386

Director of the main host Laboratory REIFFSTECK Philippe  -

PhD Speciality Géotechnique

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

Main location Marne-la-Vallée

Doctoral affiliation UNIVERSITE PARIS-EST

PhD school SCIENCES, INGENIERIE ET ENVIRONNEMENT (SIE)

Planned PhD supervisor CHEVALIER Christophe  -  Université Gustave Eiffel  -  GERS - SRO

Planned PhD co-supervisor REIFFSTECK Philippe  -  Université Gustave Eiffel  -  GERS - SRO

Planned financing Contrat doctoral  - Ifsttar

Abstract

Background:

The subject of instrumentation of hydraulic structures is an obvious subject for dams, whether it is instrumentation on new structures or on old structures: this issue of instrumentation is discussed in the legislation relating to the safety of levees and dams (MEDDE, 2015). In the case of dams, instrumentation is therefore mandatory.
For levees, nothing is imposed or even suggested, and the subject has only recently been discussed. In France, there are almost 9,000 kilometers of levees (protecting highly urbanizing watersheds, and consequently both populated and strategic for the economy and safety) placed under the management of different managers, particularly in terms of technical skills, and therefore safety relies on only visual inspections.
Actually, the development of new sensor technologies and easier access to communications makes it possible to combine these visual inspections with monitoring.
It seems useful to conduct a research work that will lead to the development of useful instrumentation for both inspection and diagnosis of the state of the structure in a time of crisis.
The monitoring of hydraulic structures currently relies mainly on visual inspections. By definition, these inspections, which take place only once or twice a year in the best cases, and do not necessarily coincide with intense climatic episodes, can only be based on surface defect observations and lead the expert to give an opinion on the importance of these defects.

Objectives:
It is proposed to develop a methodology to complement this visual inspection with in situ instrumentation measurements to examine the "non-visible" part of the structure.
The taking into account of the information non visible from outside the structure provides additional information concerning the state of stability of the structure. The degradation of earth-fill structures is a phenomenon that can develop within the structure: internal erosion is an example. Other phenomena may be associated with degradation but cannot be visually recorded, such as the assessment of soil permeability, particularly in periods of drought, with a combination of phenomena such as cracking, volume shrinkage or modification of the microstructure, which cannot be understood globally by the surface of the structure only. The mechanical properties of the soil seem to change during the lifetime of the structure, particularly under wetting-drying cycles which can decrease its stability.

Recent developments in in situ monitoring techniques (using optical fibers and low-cost sensor chains) show that it is now possible to develop long-term monitoring systems deployed on “sensitive” levees, which will allow the condition of the structure to be known continuously. Coupled with meteorological predictions in particular, it should be possible to predict the impact of these climatic events on the structure, and thus to define the level of safety of the structure with regard to future loadings, and thus increase the safety of people and infrastructure behind these structures.

This project therefore aims to develop a numerical model to assess the vulnerability of a dike against floods, based on a combination of:
- In-situ measurement data,
- Real-time or projected climate data,
- Data on river water levels/floods (hazard quantification),
- Laboratory data to define the level of degradation of materials.

These data must be processed to give an accurate answer in terms of real-time stability evaluation. This information can be communicated to managers during inspections or at the time of a crisis. The objective is to be able to predict the stability of the short-term performance of structures during floods, using the response of the soil to climatic effects by numerical modeling.

Work Plan:
- The PhD student will first have to list the different mechanisms of failures as well as their kinetics with the sequence of induced disorders and make the link with the appearance of defects that can be visible or measured,
- The PhD student will also have to carry out a laboratory program aiming to estimate the evolution of resistance as a function of the accumulation of hydraulic cycles, taking into account the evolution of the degree of saturation,
- In connection with the first two points, the PhD student will participate in the choice of sensors or type of measures to be implemented to monitor in situ the state of compacted materials, with a validation if necessary on a full-scale structure and more conventional instrumentation,
- At the same time, the PhD student will have to carry out a numerical study to simulate the evolution of the structure, according to the climatic environment and the data acquired in the laboratory.

Expected results:
Numerical modeling using monitoring data and specific sensors will allow to predict the behavior of unsaturated soils, from the initial, transient and final phase of the flooding event, from unsaturated to saturated, from the specimen scale extrapolated to the scale of the structure, in terms of failure mechanism. Reliable information must be provided during the transitional period (i.e. prior to the flooding event), which is the most critical period for a flood protection structure as it allows adequate protection measures to be taken quickly. The initial condition of the structure must be well described, including evolutions of hydraulic conductivity and shear strength. Then, depending on the good or poor condition of the structure, the EWS will be able to predict the stability of the structure from the initial state to the end of the hydro-meteorological event. The diagnosis and the prognosis of the stability of the structure are the two fundamental concepts that the thesis will integrate, including communication aspects. In parallel, the effects of climate on the mechanical and hydraulic properties of microstructures and the behaviour of different soil types will be studied to give the model a predictive character with respect to future climate change.
In terms of method, it will be very important during the thesis to couple real site data from the sensors, with laboratory tests carried out on equivalent soils, as well as numerical modelling.

References:
AN N., HEMMATI S., CUI Y.-J. 2016. Numerical analysis of soil volumetric water content and temperature variations in an embankment due to soil-atmosphere interaction. Computers and Geotechnics. Vol.83. pp40-51
ASCE. 2000. Guidelines for instrumentation and measurements for monitoring dam performance.
BALIS B., KASTZTELNIK M., BUBAK M., BARTYNSKI T., GUBALA T., NOWAKOWSKI P., BROEKHUIJSEN J. 2011. The UrbanFlood common information space for early warning systems. Procedia computer science. 4, 96-105.http://www.sciencedirect.com/science/article/pii/S187705091100069X
COURIVAUD J.R., BECK Y.-L., PERRIOLLAT J.-L., PINETTES P. 2012a. Démarche d’EDF au regard de l’utilisation des fibres optiques pour la surveillance des ouvrages hydrauliques. Validation de cette technologie lors des essais néerlandais Ijkdijk d’érosion interne.Colloque CFBR « Auscultation des barrages et des digues – pratiques et perspectives », 27-28 novembre 2012, Chambéry, France. 14 pages.
Dezert T. 2019. Combinaison d'informations ponctuelles et volumiques pour le diagnostic d'ouvrages en terre soumis à des risques hydrauliques, université de Nantes
DUNICLIFF J. 1988. Geotechnical instrumentation for monitoring field performance / John Dunnicliff with the assistance of Gordon E. Green. A Wiley-Interscience publication. ISBN 0-471-09614-8. 577 pages
INERIS, IRSTEA. 2015. Maîtrise des risques liés aux ouvrages hydrauliques (Programme DRA-91). Opération D1 : État des techniques éprouvées et innovantes pour la surveillance des digues. Rapport d’étude 02/12/2015, DRS-12-126136-13631C.
JODRY C., PALMA-LOPES S., FARGIER Y., SANCHEZ M., COTE P. 2019. 2D-ERT monitoring of soil moisture seasonal behavior in a river levee: a case study. Journal of Applied Geophysics, n°167, pp.140-151. https://doi.org/10.1016/j.appgeo.2019.05.008
MEDDE (Ministère de l’écologie, du développement durable et de l’énergie). 2015.Décret n° 2015-526 du 12 mai 2015 relatif aux règles applicables aux ouvrages construits ou aménagés en vue de prévenir les inondations et aux règles de sûreté des ouvrages hydrauliques. Publié au JORF n°0111 du 14 mai 2015 page 8218. https://www.legifrance.gouv.fr/eli/decret/2015/5/12/2015-526/jo/texte
MERIAUX P., MONIER T., TOURMENT R., MALLET T., PALMA-LOPES S., MAURIN J., PINHAS M. 2012. L’auscultation des digues de protection contre les inondations : un concept encore à inventer. Colloque CFBR « Auscultation des barrages et des digues – pratiques et perspectives », 27-28 novembre 2012, Chambéry, France. 17 pages.

Keywords : Levees, monitoring, numerical modeling, resilience, climate, vulnerability

Main host Laboratory - Referent Advisor	GERS - SRO - REIFFSTECK Philippe tél. : +33 181668386
Director of the main host Laboratory	REIFFSTECK Philippe -
PhD Speciality	Géotechnique
Axis of the performance contract	2 - COP2017 - More efficient and resilient infrastructure
Main location	Marne-la-Vallée
Doctoral affiliation	UNIVERSITE PARIS-EST
PhD school	SCIENCES, INGENIERIE ET ENVIRONNEMENT (SIE)
Planned PhD supervisor	CHEVALIER Christophe - Université Gustave Eiffel - GERS - SRO
Planned PhD co-supervisor	REIFFSTECK Philippe - Université Gustave Eiffel - GERS - SRO
Planned financing	Contrat doctoral - Ifsttar
Abstract Background: The subject of instrumentation of hydraulic structures is an obvious subject for dams, whether it is instrumentation on new structures or on old structures: this issue of instrumentation is discussed in the legislation relating to the safety of levees and dams (MEDDE, 2015). In the case of dams, instrumentation is therefore mandatory. For levees, nothing is imposed or even suggested, and the subject has only recently been discussed. In France, there are almost 9,000 kilometers of levees (protecting highly urbanizing watersheds, and consequently both populated and strategic for the economy and safety) placed under the management of different managers, particularly in terms of technical skills, and therefore safety relies on only visual inspections. Actually, the development of new sensor technologies and easier access to communications makes it possible to combine these visual inspections with monitoring. It seems useful to conduct a research work that will lead to the development of useful instrumentation for both inspection and diagnosis of the state of the structure in a time of crisis. The monitoring of hydraulic structures currently relies mainly on visual inspections. By definition, these inspections, which take place only once or twice a year in the best cases, and do not necessarily coincide with intense climatic episodes, can only be based on surface defect observations and lead the expert to give an opinion on the importance of these defects. Objectives: It is proposed to develop a methodology to complement this visual inspection with in situ instrumentation measurements to examine the "non-visible" part of the structure. The taking into account of the information non visible from outside the structure provides additional information concerning the state of stability of the structure. The degradation of earth-fill structures is a phenomenon that can develop within the structure: internal erosion is an example. Other phenomena may be associated with degradation but cannot be visually recorded, such as the assessment of soil permeability, particularly in periods of drought, with a combination of phenomena such as cracking, volume shrinkage or modification of the microstructure, which cannot be understood globally by the surface of the structure only. The mechanical properties of the soil seem to change during the lifetime of the structure, particularly under wetting-drying cycles which can decrease its stability. Recent developments in in situ monitoring techniques (using optical fibers and low-cost sensor chains) show that it is now possible to develop long-term monitoring systems deployed on “sensitive” levees, which will allow the condition of the structure to be known continuously. Coupled with meteorological predictions in particular, it should be possible to predict the impact of these climatic events on the structure, and thus to define the level of safety of the structure with regard to future loadings, and thus increase the safety of people and infrastructure behind these structures. This project therefore aims to develop a numerical model to assess the vulnerability of a dike against floods, based on a combination of: - In-situ measurement data, - Real-time or projected climate data, - Data on river water levels/floods (hazard quantification), - Laboratory data to define the level of degradation of materials. These data must be processed to give an accurate answer in terms of real-time stability evaluation. This information can be communicated to managers during inspections or at the time of a crisis. The objective is to be able to predict the stability of the short-term performance of structures during floods, using the response of the soil to climatic effects by numerical modeling. Work Plan: - The PhD student will first have to list the different mechanisms of failures as well as their kinetics with the sequence of induced disorders and make the link with the appearance of defects that can be visible or measured, - The PhD student will also have to carry out a laboratory program aiming to estimate the evolution of resistance as a function of the accumulation of hydraulic cycles, taking into account the evolution of the degree of saturation, - In connection with the first two points, the PhD student will participate in the choice of sensors or type of measures to be implemented to monitor in situ the state of compacted materials, with a validation if necessary on a full-scale structure and more conventional instrumentation, - At the same time, the PhD student will have to carry out a numerical study to simulate the evolution of the structure, according to the climatic environment and the data acquired in the laboratory. Expected results: Numerical modeling using monitoring data and specific sensors will allow to predict the behavior of unsaturated soils, from the initial, transient and final phase of the flooding event, from unsaturated to saturated, from the specimen scale extrapolated to the scale of the structure, in terms of failure mechanism. Reliable information must be provided during the transitional period (i.e. prior to the flooding event), which is the most critical period for a flood protection structure as it allows adequate protection measures to be taken quickly. The initial condition of the structure must be well described, including evolutions of hydraulic conductivity and shear strength. Then, depending on the good or poor condition of the structure, the EWS will be able to predict the stability of the structure from the initial state to the end of the hydro-meteorological event. The diagnosis and the prognosis of the stability of the structure are the two fundamental concepts that the thesis will integrate, including communication aspects. In parallel, the effects of climate on the mechanical and hydraulic properties of microstructures and the behaviour of different soil types will be studied to give the model a predictive character with respect to future climate change. In terms of method, it will be very important during the thesis to couple real site data from the sensors, with laboratory tests carried out on equivalent soils, as well as numerical modelling. References: AN N., HEMMATI S., CUI Y.-J. 2016. Numerical analysis of soil volumetric water content and temperature variations in an embankment due to soil-atmosphere interaction. Computers and Geotechnics. Vol.83. pp40-51 ASCE. 2000. Guidelines for instrumentation and measurements for monitoring dam performance. BALIS B., KASTZTELNIK M., BUBAK M., BARTYNSKI T., GUBALA T., NOWAKOWSKI P., BROEKHUIJSEN J. 2011. The UrbanFlood common information space for early warning systems. Procedia computer science. 4, 96-105.http://www.sciencedirect.com/science/article/pii/S187705091100069X COURIVAUD J.R., BECK Y.-L., PERRIOLLAT J.-L., PINETTES P. 2012a. Démarche d’EDF au regard de l’utilisation des fibres optiques pour la surveillance des ouvrages hydrauliques. Validation de cette technologie lors des essais néerlandais Ijkdijk d’érosion interne.Colloque CFBR « Auscultation des barrages et des digues – pratiques et perspectives », 27-28 novembre 2012, Chambéry, France. 14 pages. Dezert T. 2019. Combinaison d'informations ponctuelles et volumiques pour le diagnostic d'ouvrages en terre soumis à des risques hydrauliques, université de Nantes DUNICLIFF J. 1988. Geotechnical instrumentation for monitoring field performance / John Dunnicliff with the assistance of Gordon E. Green. A Wiley-Interscience publication. ISBN 0-471-09614-8. 577 pages INERIS, IRSTEA. 2015. Maîtrise des risques liés aux ouvrages hydrauliques (Programme DRA-91). Opération D1 : État des techniques éprouvées et innovantes pour la surveillance des digues. Rapport d’étude 02/12/2015, DRS-12-126136-13631C. JODRY C., PALMA-LOPES S., FARGIER Y., SANCHEZ M., COTE P. 2019. 2D-ERT monitoring of soil moisture seasonal behavior in a river levee: a case study. Journal of Applied Geophysics, n°167, pp.140-151. https://doi.org/10.1016/j.appgeo.2019.05.008 MEDDE (Ministère de l’écologie, du développement durable et de l’énergie). 2015.Décret n° 2015-526 du 12 mai 2015 relatif aux règles applicables aux ouvrages construits ou aménagés en vue de prévenir les inondations et aux règles de sûreté des ouvrages hydrauliques. Publié au JORF n°0111 du 14 mai 2015 page 8218. https://www.legifrance.gouv.fr/eli/decret/2015/5/12/2015-526/jo/texte MERIAUX P., MONIER T., TOURMENT R., MALLET T., PALMA-LOPES S., MAURIN J., PINHAS M. 2012. L’auscultation des digues de protection contre les inondations : un concept encore à inventer. Colloque CFBR « Auscultation des barrages et des digues – pratiques et perspectives », 27-28 novembre 2012, Chambéry, France. 17 pages.
Keywords :	Levees, monitoring, numerical modeling, resilience, climate, vulnerability

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