No abstract is provided for this article.
L'article présente l'essai de cisaillement à la grande boîte de Casagrande à travers le banc expérimental développé par IRSTEA. Ce banc a été développé à l'origine pour l'étude des propriétés de résistance au cisaillement des sols grossiers. Il a connu au fil de ses perfectionnements des évolutions métrologiques et de pilotage qui permettent d'obtenir des lois de comportement et d'interfaces sous chemins de contraintes ou déformations contrôlés par ordinateur, la réalisation d'essais en conditions saturées, la détermination des contraintes résiduelles et la mise en œuvre d'essais cycliques. Des équipements particuliers ont été conçus pour répondre aux besoins spécifiques des essais d'interfaces géosynthétiques – géomatériaux et des dispositifs d'étanchéité par géosynthétiques. Par la suite, ce banc d'essai a été utilisé dans le cadre de projets de recherche et a permis des applications originales en géomécanique. L'article présente des travaux destinés à la caractérisation des propriétés de frottement de ballasts, à l'évaluation des conditions de stabilité sur pente des géosynthétiques, à la caractérisation de la résistance au cisaillement de bétons compactés au rouleau (BCR) et au renforcement des sols par la végétation.
and the 89 th annual meeting of the International Commission on Large Dams (ICOLD-CIGB) in Marseille.As part of this global event, the CFBR will be organizing a symposium on the role of dams and particularly on the multi-use of water that these dams make possible.This theme has been particularly important for at least two decades and continues to focus the attention of more and more leaders around the world.
Le bon fonctionnement des réseaux de digues et de voiries constitue un enjeu majeur pour la gestion des risques et la résilience des territoires. Le manque général de données permettant de décrire leurs comportements pour les événements rares redoutés conduit à exploiter principalement les dires experts pour estimer leurs niveaux de fonctionnement. Le projet Incertu propose une démarche méthodologique pour la modélisation fonctionnelle des mécanismes de défaillance des infrastructures en contexte systémique, la prise en compte des incertitudes liées à l'évaluation experte de leurs mécanismes de défaillance et la réduction des biais via un modèle de calibration.
In mountain areas, long linear transport infrastructures (roads, motorways, railways, etc.) are exposed to numerous natural hazards, especially hydrological and gravity-driven events such as slope instabilities, rockfalls, or torrential hazards. These phenomena can damage infrastructure, or even lead to the destruction of large sections, causing a risk for users and a deterioration of service. Infrastructure managers face several difficulties in handling these risks. One of them is identifying and representing them, due to the scale of the infrastructure, which is composed of numerous structures and exposed to multiple hazards. In this context, a model is proposed to represent all potential failure scenarios for such infrastructures. This model is based on system reliability analysis methods: functional analysis, failure mode and effect analysis (FMEA), and fault tree analysis (FTA). It is intended to be applied to a linear infrastructure, several kilometres long, exposed to various hazards. The proposed approach allows for the identification of all possible failure modes, including damage to structures and its functional consequences. Its applicability is being tested on a simple case study.
REVUE FRANÇAISE DE GÉOTECHNIQUEN° 136 3e
No abstract is provided for this article.
In recent years, there have been many failures of flood levees (river embankments) in France following river floods. The levees are mostly old structures for which few records are available. The matter is further complicated by the size of the levee infrastructure—more than 7,500km in total length. The goal of this paper is to provide managers with methods and tools for assessing the performance of levees and to help them plan inspections, maintenance, and repair work. To do so, we developed a geographic information system (GIS) with the intention of incorporating it with the models for assessing levee performance. The first stage in this research is to model the failure mechanisms and identify performance indicators for each mechanism. The second stage is to assess levee performance with respect to each mechanism by aggregating the corresponding indicators. This paper describes the methods used for modeling levee failure and assessing levee performance. It also discusses the operational tools incorporated in the GIS.
No abstract is provided for this article.
No abstract is provided for this article.
No abstract is provided for this article.
Improving protection against fluvial floods requires a better estimation of levee failure. We developed an assessment method of levee failure probabilities for sliding, backward erosion, and overflowing each represented by fragility curves. We tested two approaches to aggregate those fragility curves into a global fragility curve respectively using: an enveloping curve and Monte‐Carlo simulations. We implemented this approach to earthen levee reliability for several flood return periods to the Bow River in Calgary, Canada. We used limit equilibrium method to estimate the safety factor of the levee segment and Monte‐Carlo simulations to estimate sliding probabilities. We used Terzaghi's critical hydraulic gradient to estimate backward erosion failure probabilities. The estimation of overflowing probabilities required expert judgment. We discussed how the choice of the hydraulic gradient area and the consideration of a steady state or transient model impact backward erosion failure probabilities. The results showed for our study case that, even though the transient model is a closer representation of reality, the levee saturation parameter has little impact on hydraulic gradient values, by extension, on sliding and backward erosion failure probabilities. The Monte‐Carlo aggregated fragility curve is more realistic than the envelop curve of the failure mechanisms for an equivalent computation time.
Dam safety assessment is a major challenge for engineers specialising in hydraulic works. It is now standardised in regulations providing for hazards studies using probability-based risk analysis procedures. Dam safety probability-based assessment includes two key scientific issues: the modelling of complex mechanisms that occur within the works, and a probability-based assessment of structural safety. This paper introduces a combined application of risk analysis and dam reliability methodologies. This combination required the completion of our work on the adaptation of risk analysis methods to dams, and on the probability-based modelling of strength and loading input data for a reliability-based analysis. These methodologies are then implemented as part of a hazards study on a roller-compacted-concrete gravity dam. Keywords: damreliabilityrisk analysissecurityhazards studyMots-clés: barragefiabilitésûreté de fonctionnementsécuritéétude de dangers
