68th Canadian Geotechnical Conference and 7th Canadian Permafrost Conference

OBSERVED DEFORMATIONS OF AN EXISTING HIGHWAY EMBANKMENT ON DEGRADING PERMAFROST

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

David Flynn, KGS Group, Winnipeg, Canada (Canada)
Marolo Alfaro, University of Manitoba (Canada)
Jim Graham, University of Manitoba (Canada)
Lukas Arenson, BGC Engineering Inc. (Canada)

The integrity of infrastructure in northern regions is negatively impacted by thawing and degradation of the underlying permafrost foundation initiated by changes in both air and ground temperatures. Subsequent deformations due to settlement and lateral spreading can lead to potentially hazardous driving conditions for linear infrastructure, such as highways. This paper discusses the deformation of an instrumented highway embankment sitting on degrading permafrost observed since September 2012. The site is located 18 km north of Thompson, Manitoba on Provincial Road (PR) 391. Earlier papers on this site reported results from three years of data, but with incomplete instrumentation. Newly-added instrumentation installed in September 2012 has identified a frost bulb in the centre of the embankment. We assessed the effect of the frost bulb, which had not been known and therefore not included in previous studies, on the embankment deformation. Lateral and vertical embankment deformations were measured using ShapeAccelArrays installed vertically below the shoulder of the embankment and horizontally at its toe. New instrumentation also included vibrating wire piezometers and thermistors to monitor groundwater and temperatures. Readings from the new instruments provide an improved understanding of the pore pressures and the thermal regime at the site.