Fine Grained Fill Placement Specification for Freezing Conditions

Concerns of placing “frozen” fill typically suspend earthworks during periods of sustained freezing temperatures. Hazards resulting from placing fill in a frozen state (soil temperature below 0°C) are well documented and include reduced strength, increased settlement and changes to permeability. For many projects there are significant benefits to continue placing fill as long as possible. Maximizing the window of fill placement requires an increased level of construction, monitoring and coordination effort. If not managed properly, freezing conditions placement can have negative impacts on the project most commonly resulting from reworking or wasting of unsuitable fill and reduced placement efficiency. In some cases project teams may choose to suspend fill placement activities earlier than could be possible because the project benefits, typically schedule, do not justify the increased effort required.

This paper presents a winter placement specification that was developed and implemented during construction of an earth fill tailings embankment in an arid desert environment where winter temperatures can be below 20°C. The fill placed was primarily comprised of high plasticity clay at near optimum moisture content. The fill placement continued as long as the fill could be compacted to the specified density prior to the internal temperature of the soil dropping to 0°C. The basis for the placement specification was governed by increased levels of: compaction applied to the soil; monitoring by design engineers; and quality control testing. Monitoring and quality control testing allowed fill placement activities to continue with air temperatures as low as -17°C. At these temperatures, construction equipment struggled to compact fill before freezing and a sharp drop off in productivity resulted in shut down of fill placement until spring.

Friedel, R.J., J.S. Casey, N. Gullayanon and M.J. Cronk. 2012. “Fine Grained Fill Placement Specification for Freezing Conditions,” in: GeoManitoba, Building on the Past, 65th Canadian Geotechnical Conference, Winnipeg, Manitoba, September 30-October 3, 2012. Toronto: Canadian Geotechnical Society.

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