The Puvirnituq airstrip pilot project; results from the first three monitoring years

摘要

The Puvirnituq airstrip was originally constructed using a thick embankment to fill a finegrained sediment filled valley. Since the construction of the airstrip, subsidence has been observed in the thick-fill area. Construction work was done in 2009 to allow the landing of a Boeing 737. As part of this work, the thermal and mechanical stabilization of the embankment that fills the valley was realized. A convective embankment with a ventilation system has been constructed. A berm, made with the same convective material was also constructed to resist a possible lateral instability of the embankment. The construction work also included the deviation of the small creek flowing in the valley. The project has two main objectives. First, it aims to improve the heat extraction system design and to validate its effectiveness in the context of the Puvirnituq airstrip. Second, the project aims to refine the evaluation procedure for stability analysis in the context of degrading permafrost. In order to determine the effectiveness of the heat extraction system, thermistor strings have been installed in the convective embankment, under the ground surface and horizontally on the ground surface under the berm. Instrumentation has shown a decreasing active layer thickness between 0.44 and 1.53 meters and evidence of convection in the convective embankment. An inclinometer was also installed at the toe of the embankment. The movement monitored by the inclinometer suggest that only vertical compression movement has occurred since the construction of the convective embankment. The movement observed would therefore be associated with the consolidation of the soil under the embankment weight.