Author(s): Hiroshi Yokoyama; Yasuhiro Yoshikawa; Hiroki Yabe; Kenji Takahashi; Satoshi Konishi
Linked Author(s): Hiroshi Yokoyama
Keywords: No keywords
Abstract: We aim to clarify ice jam mechanism under completely ice-covered river by model experiments. It had been investigated that conditions of occurrence of ice jam depended on river width, change of water. However, researches about mechanism of ice jam under completely ice-covered river caused by ice inflow from upstream has not been conducted. The experiments were conducted by channel that was simplified actual ice-covered river on a scale of 1/100. The test channel had four sections with different width and longitudinal slope. Ice plates model made by polypropylene (specific gravity was same to real ice) were fed from upstream of the channel. We conducted experiments with different river discharge, intake flux of ice, and size of ice plates. We performed two types of ice jam by setting different completely icecovered section: One was set at sudden expansion (Run C1). The other was set at sudden contraction (Run C2). In Run C2, required time for ice jam was longer with larger discharge, smaller ice plates, or larger intake flux of ice. These trends were previously confirmed in ice jam experiments under non-completely ice covered river. But in Run C1, relation between required times for ice jam and discharge or intake flux was not clear if ice plates were smaller. Longitudinal changes of channel width and bed slope differed in Run C1 and C2 and seemed to affect ice jam progress. We suggested some points for modeling these phenomena.
Year: 2018