214 publications from this institution
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Hydro-Quebec and Cemagref have implemented condition evaluation methods for water retaining structures: the condition index (CI) method for embankment dams in Quebec, and SIRS Digue for fluvial dykes in France. These methods were developed from similar approaches, including functional analysis, gathering and formalization of knowledge about failure mechanisms, and definition of performance indicators. Development of both methods was done within a group of experts and lead to technical guides that explain the application limits. The main objective is to prioritize maintenance tasks within a large inventory of dams for Hydro-Quebec, and for fluvial dykes, in France. The use of these methods reaches also other goals at the same time: aid to safety review and dam diagnosis, and experience transfer among the technical staff.
Cette communication présente une synthèse des différentes cotes et crues de référence habituellement utilisées pour l’évaluation de la sécurité d’un ouvrage hydraulique, y compris dans le cas d’un barrage écrêteur de crues ou d’une digue de protection contre les inondations. Les discussions au sein du groupe de travail du CFBR consacré à la justification de la stabilité des barrages et les travaux de recherche menés au Cemagref dans le domaine de l’analyse de risques appliquée aux ouvrages hydrauliques montrent les limites de ces définitions et ouvrent de nouvelles perspectives.Des propositions sont donc faites pour clarifier la terminologie. Cela aboutit à privilégier la détermination des cotes atteintes dans la retenue pour différents scénarios de crues. Au final, il apparaît possible d’associer des probabilités d’occurrence au dépassement de la cote de sûreté ou de la cote de danger de rupture, et parallèlement de proposer des valeurs minimales cibles pour ces probabilités, en fonction des types d’ouvrages et de leur classe.This paper presents a synthesis of different level and flood references usually used for assessing the safety of hydraulic structures, including dams for flood control or dikes for flood protection. Discussions in the FrCOLD working group on justification for the stability of dams and research conducted by Cemagref in the field of risk analysis applied to hydraulic works show the limits of these definitions and open new perspectives. Proposals are made to clarify terminology. This leads to emphasize the determination of levels reached in the reservoir for different scenarios of flooding. Then it is possible to associate probabilities of occurrence to the maximum water level and to the level of danger of rupture, and parallel to propose minimum targets for these probabilities, depending on the types of hydraulic works and their class.
The behavior of the civil engineering infrastructures, and their interactions during a flood event, will have consequences on the flood risk level in the built environment. By civil engineering we include on one hand the flood defenses, able to increase the flood risk in case of failures, on the other hand the urban technical networks able to spread the flood risk in cities. From history, most of cities in the world have been built close to coast lines or to river to beneficiate this means of communication and trade. Step by step, to avoid being flooded, defenses like levees have been built. The capacity of the levees to retain the floods depends on their conditions, their performance level and the capacity of the authorities to well maintain these infrastructures. Then, in case of levee break, cities will be flooded. The urban technical networks, due to the way they have been designed, their conditions and their locations in the city, will play a major role in the diffusion of the flood extent. Also, the flood risk will have consequences in some not flooded neighborhoods due to networks collapses. The methods we are using to determine the performance level of flood defenses and the level or resilience of the urban networks with three specific capacities are described. Then, an integrated spatial decision support system is presented.
La France subit de fréquents épisodes de crues dévastatrices. Les inondations provoquent d'importants dégâts et les coûts induits sont considérables. Les digues de protection contre les inondations, souvent sous-dimensionnées et mal entretenues, ont montré leurs faiblesses à plusieurs reprises et leurs ruptures augmentent la violence des inondations. A l'échelle nationale, le linéaire conséquent de digues (environ 7 500 km) et le manque de données sur l'ensemble de ce parc d'ouvrages compliquent leur gestion. A l'échelle du gestionnaire local se pose la question de l'optimisation des opérations de maintenance. Notre recherche vise à développer des méthodes d'évaluation de la performance des digues. Dans un premier temps, nous développons un modèle fonctionnel pour représenter les mécanismes de rupture des digues. Ce modèle permet de représenter des mécanismes sous forme de scénarios et de dégager les indicateurs pertinents de la performance des digues.
Both in France and at the global level, hydraulic works have remained excluded from semi-probabilistic regulations. As far as embankment hydraulic works are more specifically concerned, there are no formal rules for their design. In this context, the French Commitee on Large Dams initiated a research project to define a semi-probabilistic limit-state method for the design of embankment hydraulic works. This paper accounts for the work done over two years. It determines the position of embankment hydraulic works in relation to Eurocode 7. It briefly outlines the suggested semi-probabilistic limit-state method and focuses on the sliding limit-state. Applying the method to a pseudo-homogenous dam helps comparing the standard deterministic practice, the Eurocode 7-based approach and the developed semi-probabilistic method.
More and more floods occurred over the last decade in France and in the world, causing important damages and significant costs. Moreover, levees are often not well maintained, so they hardly resist to major floods and can break easily.\nAt French national scale, the length of levees, estimated to 7500 kilometers, and the lack of data all along these infrastructures complicates their management. In this frame, levee managers need approaches and tools in order to be helped in their maintenance decision.\nThe goal of our research is to develop methods modeling levee failure mechanisms and allowing performance levee assessment. From collected data (detailed visual inspections, laboratory tests, historical data, etc.), we establish indicators able to assess levee condition and performance. These methods integrated in an existing GIS dedicated to levee management will contribute to obtain a spatial decision support system aiding levee managers in their maintenance decision.\nOur communication presents in a first part the development of the Levee GIS and an example of its current functionalities. In a second part we describe the models that have been set up to assess levee performances and we describe their integration into a new prototype version of the Levee GIS. / Plusieurs crues significatives, accompagnées de ruptures de digues, ont eu lieu ces dix dernières années en France. Ces ruptures aggravent le risque d'inondation dans les zones que les digues sont censées protéger. Les gestionnaires de digues ont besoin de méthodes et d'outils pour mettre à niveau et maintenir la sécurité des digues. Cet article présente les méthodes qui ont permis de modéliser les ruptures de digues, d'évaluer leur performance, et le couplage de ces méthodes avec l'outil SIG spécifiquement dédié à la gestion des digues.
