Four-year monitoring of a geotextile-reinforced fill slope along a highway to Canada’s Arctic Coast

A reinforced highway embankment test section was constructed along the Inuvik-Tuktoyaktuk Highway in Northwest Territories, Canada. The embankment was constructed under frozen conditions for logistical and environmental reasons. There is limited understanding on the mechanical behaviour of embankments that are initially compacted with frozen fill and then experience natural thawing during subsequent summer seasons. Side-slope sloughing and fill cracking occur due to localized thaw-settlements under the shoulders and side-slopes of the embankment in combination with the depression of the permafrost table at the toe of the embankment. In order to minimize these issues, layers of wicking geotextiles were installed to provide reinforcement at the slopes and drainage path for the water during the thawing season. Strain gauges were installed along the geotextiles to measure its elongation, while ShapeAccelArrays were installed mid-slope and mid-height of the embankment to measure lateral and vertical displacements, respectively. Thermistor strings were also installed at different locations in the embankment fill and foundation soil to monitor soil temperatures. A control test section (unreinforced) with the same instrumentation was also constructed beside the reinforced test section to evaluate the benefit of using wicking geotextiles in Arctic environment. This paper presents four years of monitored performance of both control and reinforced test sections.