Geology Reference
In-Depth Information
Figure 14.8.
At Yellowknife, NWT, Canada, the Rockcliffe residential apartment building expe-
rienced thaw subsidence and weakening of the pile foundations. Remedial action involved the
installation of thermosyphons beneath the building. From Wolfe (1998).
settlement of underlying sediment. The crawl space enlarged from 1 m to 4 m in height
over a 20-year period. The piles became stressed and the building began to shift. In 1994,
the expanded crawl space was fi lled and leveled with aggregate and thermosyphon tubes
were installed to remove heat from within the fi ll. By 1997, the infi ll had cooled to 0 °C
and quasi-stability of the piles had been re-established.
One of the main streets of downtown Yellowknife is Franklin Avenue. This important
street joins the old and new parts of the city. The deteriorating water and sewage systems
that extended along the street were replaced in 1990. This followed upon many years of
constant maintenance by city workers and several major episodes of leveling and road
resurfacing. Since 1967, thaw subsidence had been generated by the service mains that
were buried beneath the road. This was accentuated by the dark asphalt surface. In
1989-1990, geotechnical investigations were undertaken prior to reconstruction of the new
