GEOSCAN, résultats de la recherche


TitreMonitoring the effect of telluric currents on water mains
AuteurWeston, G; Samson, C; Boteler, D H; Trichtchenko, L; Raymond, D
SourceProceedings of ASTRO 2008; 2008 p. 1-8; 1 CD-ROM
Séries alt.Secteur des sciences de la Terre, Contribution externe 20100359
RéunionASTRO 2008; Montreal; CA; avril 29 - mai 1, 2008
MediaCD-ROM; numérique
Sujetslevés telluriques; champ tellurique; interpretations telluriques; courants magnétosphériques; variations solaires; pipelines; géophysique
Illustrationsdiagrams; aerial photographs; graphs; plots
ProgrammeTargeted Hazard Assessments in Northern Canada, Géoscience pour la sécurité publique
Résumé(disponible en anglais seulement)
Telluric currents on a 1-km long cathodically-protected water main section in Ottawa were monitored between May and November, 2007. Data-loggers attached to 9 test posts along the water main recorded a repeated variation in pipe-to-soil potential, which correlated to diurnal variations in the geomagnetic field. Analysis of the data in the spectral domain revealed two dominant peaks at periods of 24 and 12 hours. To investigate spatial variations along the water main, the data recorded at each test post were plotted against a reference test post. An overall decrease in relative amplitude and DC offset was observed from west to east, as distance from the current source of the cathodic-protection system increases. While telluric current induction was evident during the study, the resulting PSP variations too small to compromise the cathodic-protection system. Periods of more active geomagnetic disturbances, however, could still remove the water main from the safe PSP ranges of -0.85 V to -1.35 V, making it more susceptible to corrosion.