Journal of Cold Regions Engineering

Winter operation of the New York Power Authority's and Ontario Hydro's hydropower generating stations on the Niagara River is affected by the possibility that ice jams might occur in the vicinity of the hydropower plant intakes. In this study, a two dimensional numerical model was used to study the ice transport and jamming processes in the vicinity of hydropower intakes in the upper Niagara River. The model was also used to analyze the effectiveness of several possible structural and operational measures that might be used to mitigate the occurrence of ice jams and improve winter power production.

The dependence of overall elastic and viscoelastic behavior of polycrystals on properties of hexagonal single crystals of ice is predicted using established methods of micromechanical analysis. The self-consistent and bounding methods are used first to relate elastic behavior of S2 columnar and granular ice to single crystal properties. The results for S2 ice are then extended to viscoelastic behavior in order to relate overall creep behavior, as well as other time and rate-dependent behavior, to crystal parameters. Good agreement with experimental results is shown. Emphasis in this paper is on linear viscoelastic behavior of S2 ice due only to intragranular creep. The effect of this creep and grain boundary sliding on microcracking is considered briefly in the concluding remarks.

Although the effects of climate on pavement structures are recognized as major contributors to the deterioration of pavement structures in cold regions, only a few models concerned with both frost heave and thaw settlement have been developed. In this study, a coupled mass and heat transfer model, FROSTB, developed by the U.S. Army Cold Regions Research and Engineering Laboratory (CRREL) was tested and evaluated with respect to parameters critical to thaw weakening. With the main focus on soil moisture and temperature, the results were compared with data from an instrumented test road. The results indicate the soil temperature is predicted very well and soil moisture relatively well during freezing and thawing. Although a time lag was observed between observed and predicted start of thaw, the results suggest that the FROSTB model may serve as a good tool for many engineering purposes involving the freezing and thawing of pavement structures in cold regions.

Although elastic multilayer techniques for pavement analysis have become increasingly popular through advances in software and personal computers, the difficulties of such methods in representing dynamic loading, pavement geometry and nonlinear material response are widely recognized as significant. Particularly in cold regions, where pavement materials are subject to seasonal freezing and thawing, nonlinear material behavior cannot be accurately modeled with these methods. However, many of these difficulties can be overcome by using the finite element method. In this study, an initial attempt to implement a commercially available finite element code in an analysis procedure for pavements in seasonal frost areas is presented. The results, compared with data from an extensively instrumented test road, show that surface deflections and the relative change in pavement stiffness, indicated by the subgrade strength index, are predicted very accurately. Although a time lag between maximum measured and predicted surface deflection is observed during thawing, the procedure is found to be promising and further research is warranted.

The frost susceptibility for 100% glass cullet specimens and 30% by weight glass cullet-aggregate specimens was determined using ASTM D 5918. The cullet has negligible to very low frost susceptibility, and it did not increase the frost susceptibility of the aggregate. Based on a comparison of grain size distributions of the cullet and aggregates with the work of others, we conclude that the material tested represents typical cullet for which other engineering properties have been determined; therefore, this information can be added to the current body of knowledge about the engineering properties of glass cullet.