Journal of Cold Regions Engineering

Extreme-value statistics for the maximum depth of soil freezing are developed based on a physical soil freezing model and a semiphysical soil water budgeting scheme. The model uses only daily air temperature, snow depth, and precipitation data. These data are available from a relatively dense network of observing stations, permitting the development of a national climatology of extreme soil freezing levels. A set of adjustment factors is also presented that allows conversion between the mapped base-soil freezing depths and those associated with other soil conditions. Surface cover characteristics of bare soil with and without ambient snow cover and turf are analyzed. The deepest soil freezing levels within the United States are found across the Dakotas, where persistent subfreezing winter temperatures, and relatively little soil moisture and snow cover combine to maximize soil freezing. Ample winter snow cover mitigates soil freezing extremes in the Great Lakes, northern New England, and western mountains. Soil freezing is unlikely south of northern Florida and the immediate Gulf Coast, along the California coast, and in southern Arizona.

A series of experiments on the physical and mechanical properties of ethanol model ice were conducted to determine the basis for quality control of fine grain model ice. The measured physical parameters of the model ice included the ethanol solution freezing point, air temperature profiles in an ice basin, ice temperature profiles, solution temperature profiles, unfrozen liquid in ice, and ice density. The measured mechanical parameters of the model ice were compressive strength, flexural strength, and characteristic length and strain modulus. Based on these measurements, the dominating factor influencing the physical and mechanical parameters of model ice is found to be the amount of unfrozen liquid in ice. Therefore, a new index of quality control for the physical and mechanical parameters of ice is developed. The statistical relationships of these measured physical and mechanical parameters with the new index are shown.

Adhesion of ice to surfaces creates problems for many industries, including aviation, hydropower, telecommunications, navigation, electrical distribution, and all forms of transportation. Specific problems at locks and dams include ice buildup on lock walls and miter gates, and spillway gate freeze up, preventing opening on short notice. At present, ice removal techniques are both costly and time-consuming. In an effort to reduce the cost, time, and physical labor associated with ice removal, much research on ice adhesion has been done. This work ranges from theoretical studies to microscopic investigations and full-scale field tests. The main focus of all of these studies is how to lower ice’s adhesive strength, thus easing ice removal. Three principal methods to lower ice’s adhesive strength have been pursued—electrical, chemical, and mechanical. Of the three methods, the mechanical removal of ice has received the least amount of attention. Three approaches have been taken with regard to electrical methods. They are using heaters, creating an electrical pulse that mechanically breaks the ice, and applying a direct current bias to change the ice’s adhesion. The search for a low adhesive coating or material has by far received the most attention of any method pursued for lowering ice’s adhesive strength. A class of chemicals containing polysiloxanes has shown promise in providing a low adhesion surface. Based on this review, we recommend that an electroexpulsion method developed for the space shuttle and a newly formulated polysiloxane be tested as to their feasibility in the lock and dam environment.