HIGH-RESOLUTION MONITORING OF THAW SUBSIDENCE AFFECTING THE ACCESS ROAD TO UMIUJAQ AIRPORT IN NUNAVIK (QUEBEC)

Richard Fortier, Shuai Guo, Pierrick Lamontagne-Hallé, Wenbing Yu

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

Session: Infrastructure Performance in Cold Regions II / Performance des infrastructures en régions nordiques II

ABSTRACT: The thaw subsidence along a 300 m long segment of the access road to Umiujaq Airport in Nunavik (Quebec) has been annually monitored since 2006. This subsidence is due to thaw consolidation taking place in a layer of ice-rich silt underneath the road embankment. The increase in air temperature over the last two decades and the thermal insulation of snow cover on the embankment shoulders and toes explain the permafrost degradation. Thaw subsidence as much as 1.50 m has been recorded since the road completion in 1991. Rates of thaw subsidence from 0.056 to 0.138 m/year were observed. According to numerical modeling, the thawing rate is 0.317 m/year. The coefficient of consolidation varies between 1.37 and 2.44 m2/year for corresponding thaw consolidation ratio from 1.021 to 0.765. The thaw consolidation of the silt layer is almost completed and only little thaw subsidence is expected along the monitored road.

RÉSUMÉ: e couche de silts riche en glace augmentation de la températDes tassements au dégel aussi élevés que 1.50 m ont été observés en 1991. Des taux de tassement de 0.056 à 0.138 m/an ont été mesurés. Selon des simulations numériques, le taux de dégel estimé est de 0.317 m/an. Les coefficients de consolidation obtenus varient de 1.37 à 2.44 m2/an pour des rapports de consolidation au dégel correspondants de 1.021 à 0.765. La consolidation au dégel de la couche de silt est presque complétée et de faibles tassements au dégel sont seulement attendus le long du segment de route étudié.

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