Journal of Cold Regions Engineering

Slippery road surfaces are a threat to traffic safety, especially in winter when snow falling on roads forms a hard crust that is extremely difficult to remove. To prevent this hard crust formation, salt is applied to roads. However, large amounts of salt are harmful to the environment and expensive. Therefore, optimization of salt applications has become a priority for transportation agencies. This study evaluates the effects of sodium chloride (NaCl) aqueous solution on compacted snow through a field investigation. A test car was driven on snow mixed with different amounts of aqueous NaCl solution (from 0% to 40% by weight); this experimental run was repeated approximately 20 times. A scraping test was also performed to evaluate the compacted salted snow’s strength. The study found that an aqueous solution content of 10% by weight keeps snow loose and easily removable from the road, but an aqueous solution of 5% by weight weakens the snow substantially, allowing the snow mixture to be more easily plowed.

Ice formation processes have been monitored on the Assiniboine River, Manitoba, by establishing an extensive network of hydrometric equipment and trail cameras. Although much of the study area is often subject to mechanical freeze-up jams, thermally driven border ice growth is typically observed just upstream of the Assiniboine’s confluence with the Red River. Unlike mechanical border ice growth, thermal border ice forms slowly and is better suited for data acquisition through time-lapse photography. Using photogrammetry and an automated digital image processing algorithm developed for trail camera imagery, one-dimensional border ice growth rates have been quantified. The presented combination of tools and techniques provide high frequency data that are a safe and economic alternative to more traditional site surveys and satellite imagery. Processed time-lapse photos have been used to support the enhancement of a two-dimensional numerical model for thermal border ice growth.

This paper presents findings from a numerical model used to conduct experiments regarding the influence of channel morphology on ice conveyance and bridging. The morphologies considered are meandering rectangular channels and rectangular channels with islands, channel tributaries, and confluences. The experiments simulated depth-averaged flow and the dynamics of ice-piece movement (two sizes of ice pieces). The results include relative time of ice conveyance along the channel and times to ice clogging and bridging for varying channel meandering. Further, the results show that channel meandering delays ice bridging because it disperses ice pieces, whereas Froude number may hasten or retard time to bridging by dispersing ice or hastening ice congestion. In addition, ice pieces at the front of a group of ice pieces may on average travel slower along the channel than ice pieces in the middle of the group. The results lead to a chart indicating when bridging occurs for ice conveyance in channels of differing meandering or morphology.

Liquid nitrogen freezing technology is widely applied to reinforce the water-bearing ground around launching and receiving shafts of shield machines in subway tunnel construction projects. An improved liquid nitrogen freezing pipe that can be cut by a shield machine is proposed in this paper. The improved pipe features a plastic outer pipe instead of a stainless steel outer pipe into which small-diameter holes are symmetrically drilled at equal distances along the wall of the inlet pipe to ensure the uniformity of the wall temperature. A model test was conducted to examine the liquid nitrogen freezing-temperature field of the improved plastic freezing pipe. Model test results showed that the wall temperature is unevenly distributed when the traditional freezing pipe (i.e., one that is open only at the bottom of the inlet pipe) is used for liquid nitrogen freezing. By contrast, a relatively uniform wall temperature distribution was obtained when the improved freezing pipe (i.e., with equidistant holes drilled on the wall of the inlet pipe) was used. Similarity ratios indicated that, if a 100-mm-diameter improved plastic freezing pipe is used for on-site liquid nitrogen freezing, the growth velocity of the frozen soil is approximately $75–150\mathrm{mm}/\mathrm{day}$.