Grant: Alliance Grants

River ice is an important factor affecting alluvial channels in Canada. A major consequence of ice-cover formation on many rivers is the ice jams that occur very often in rivers across Canada. Ice jam is one of the most conspicuous and momentous of the ice-related phenomena. Due to a large aggregate ice thickness and a high hydraulic resistance relative to the sheet ice cover, the presence of an ice jam can cause more local scours at bridge piers compared to that under the sheet ice-covered condition. However, due to the instantaneous changes of ice jam thickness and associated local scour at bridge piers, field observations in natural rivers have been impossible because of the high levels of risk involved. To avoid this risk, the proposed research will be conducted in a laboratory flume. Polyethylene particles with mass density of 0.918 g/cm3 will be used to model ice particles. Five sands with the different median particle sizes and three different shapes of model piers will be used, namely cylindrical, rectangular, round end-shaped piers, respectively. Experiments will be conducted under different conditions including open flow, sheet ice-covered and ice-jammed flow conditions.Investments in infrastructure such as bridges and hydraulic structures that subsequently fail due to riverbed scour at bridge piers under ice-jammed flow conditions are a serious problem and are economically wasteful. The proposed research will contribute to a better understanding of deformation processes of riverbeds at bridge piers under ice-jammed flow conditions, thereby informing improved infrastructure design by engineers.