MESURES DE RADAR EN PUITS POUR LA LOCALISATION DU NOYAU IMPERMÉABLE DU BARRAGE ROMAINE 2

Michel Chouteau, Ting-Kuei Chou, Alain Côté

In the proceedings of: GeoQuébec 2015: 68th Canadian Geotechnical Conference & 7th Canadian Permafrost Conference

Session: Embankments and Dams / Remblais et barrages

ABSTRACT: Radar surveys were conducted in the two vertical inclinometers located at the top of the Romaine 2 dam, on both sides of its asphaltic core, after filling the reservoir to 95% of the dam capacity. Tomography surveys between downstream and upstream inclinometers allowed the determination of the 2-D radar velocity distribution, directly related to water content. The radar reflection surveys have highlighted two reflectors parallel to the inclinometers at distances of ~ 2 m and 3.4 m respectively. The first could be linked to a variation in particle size composition between the protection material surrounding the inclinometer and the compacted embankment located on each side of the core. The second would be attributable to the embankment/core interface. The interfaces were resolved with an uncertainty of 30 cm to 40 cm approximately because of the weak reflections and the significant noise level. A strong attenuation of the radar signal at the base of the dam prevented from determining the position of the core in the vicinity of the concrete base. Two parallel steeply dipping reflectors have been highlighted between 35 and 50 m depth in the upstream inclinometer. They were not present during the survey carried out when the reservoir was empty.

RÉSUMÉ: bitumineux du barrage Romaine 2, après le remplissage à 95% du réservoir. Les levés de tomographie entre les inclinomètres amont et aval ont permis de déterminer le champ 2-D des vitesses de propagation radar associées directement à la teneur en eau. Les levés radar en mode réflexion ont mis en évidence deux réflecteurs parallèles aux inclinomètres se situant à ~ 2 m et 3,4 m respectivement. Le premier serait lié à une variation de composition compacté noyau. Le second spermis de positionner cette interface 30 cm à 40 cm près. Une forte atténuation du signal radar localisée à la mis de déterminer la position du noyau au niveau de son assise sur le socle en béton. Deux réflecteurs parallèles à fort pendage ont été mis en évidence entre 35 et 50 m de profondeur dans l'inclinomètre rsque le réservoir était vide.

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