Author(s): Taro Koike; Yasuhiro Yoshikawa; Hiroshi Yokoyama
Linked Author(s): Hiroshi Yokoyama
Keywords:
Abstract: In this study, we aimed to clarify the phenomenon of ice-jam flooding generated around bridge piers. Depositing real ice in a river channel is an integral part of investigating ice-jam flooding around river structures. However, the effects of flooding and the destructive mechanism of deposited ice have not been considered in most previous experimental studies. We chose here to conduct an ice-jam flooding experiment in a compound river channel. In the experiment, polypropylene plates and real-ice plates were used to model the river ice. In a series of experiments, we examined the speed and number of jammed plates around bridge piers according to the modeled-ice at the time of the ice-jam occurrence, the flooding situation in the high-water channel, and water level changes. The study results are the following. (1) Because of the experimental ice jams, speed was decreased and number of plates was increased in the modeled-ice; (2) the ice in the model detoured around bridge piers and flowed in the high-water channel, but eventually flowed into the low-water channel downstream; (3) after the ice jam developed, flooding began on the upstream side of the ice-jam site. Over time, floodwaters flowed downstream from the ice-dam site; (4) flooding speed was fast when discharge was large. Over time, the flooded area stabilized; (5) in the vicinity of ice-jam sites, upstream water level increased and downstream water level decreased until sudden reversals after ice jams broke; (6) ice-jam occurrence was greatly influenced by discharge; (7) the rise in water depth apparently had a big influence on the discharge of ice.
Year: 2020