214 publications from this institution
Les racines d’arbre sont reconnues comme un danger lorsqu’elles poussent dans les structures en remblai d’ouvrages hydrauliques, et notamment des digues. Deux principaux risques sont associes a la presence d’arbres sur ces ouvrages : l’erosion interne liee au developpement racinaire dans le corps de digue ou sa fondation et l’erosion externe relative au deracinement potentiel de grands arbres sous l’effet du courant ou du vent. L’objectif des travaux de these, est d’elaborer des methodes de prospection non destructives permettant de reperer et evaluer les developpements racinaires dangereux dans les ouvrages hydrauliques. Pour cela, une methodologie couplant une approche experimentale et de modelisation est etablie dans le but de caracteriser le systeme racinaire. / Roots are recognized as an environmental hazard when growing in hydraulic earth structures, especially dikes. Trees’ rooting in earth dikes generates two types of risks: internal erosion due to root development in earth embankments or their foundation, and external erosion (slopes and crest) which is often related to trees uprooting by the effects of currents or wind. The aim of the beginning thesis, subject of this paper, is to elaborate non-destructive prospection methods able to detect and evaluate dangerous tree roots growing in dike or dam body. To this end, we have to design a methodology including non-destructive methods and geophysical models in order to characterize the root system. Several geophysical methods are often used for exploration of soil. Nevertheless, given the complex variety of bank and soil properties composing earth dikes, these non destructive methods have to be adapted and improved to detect and localize woody roots in these specific conditions.
No abstract is provided for this article.
Click to increase image sizeClick to decrease image sizeThe use of gabions in the small dams in the Sahel regions of Africa is quite common, they are used in flood spillways in which the gabion weirs are usualtechniques. Indeed, apart from a good mechanical stability and a high level of resistance to flood flows, gabion weirs enable a large amount ofpredissipation of water energy before the stilling basin. In the present state of the technique the right dimensions for this type of structure are not well known. To define energy dissipation on the shoulders a systematic study of the standardized wasteways from 3 to 5 m high, for a flow rate of up to 3 m3/s per meter width, has been carried out on scale models on 1/5 scale.It has enabled the amount of energy dissipation to be quantified and enabled determination of dimensioning parameters for the stilling basin. The results obtained lead to a saving of 10 to 30 % over the length of the stilling basin compared to the lengths obtained with the methods used up to present. Moreover, we also wished to classify the flows on the shoulders and define the phenomena observed during the different hydraulic regimes.
No abstract is provided for this article.
Cemagref and ISL consulting engineers produced for Nîmes city (France) a reliability study concerning a hydraulic works system, composed of several dams, singular civil works, canals and collectors networks, and intended to ensure protection against floods. This study constitutes one of the first quantitative reliability studies of a hydraulic works system realized in France. This article presents the step and the methodologies used in a reliability quantitative analysis. The methodological developments are illustrated all along the text through this remarkable application.
REVUE FRANÇAISE DE GÉOTECHNIQUEN° 136 3e
[Departement_IRSTEA]Eaux [TR1_IRSTEA]RIVAGE
No abstract is provided for this article.
RESUME – L'article presente a travers le recent guide de recommandations Retenues d’altitude la synthese d'un retour d’experience sur le comportement et la pathologie des dispositifs d’etancheite par geomembrane en altitude. Il donne les recommandations fortes du guide relatives a ces dispositifs, en particulier sur la structure support, le drainage inherent au DEG et la structure de recouvrement. Un descriptif general du guide termine l'article. Mots-cles : Retenues, altitude, etancheite, geomembrane, recommandations
