Author(s): Ken-Ichi Hirayama; Norima Sakamoto; Norihiro Takeuchi; Ichiya Obara; Makoto Sasamoto
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Abstract: For the first time in "Honshu", the main land of Japan, ice influence was considered for newly planned structures on the shore of Lake Ogawara in Aomori Prefecture. In this area the freezing index seldom exceeds 200°C day, but large ice movements have been reported in the past. To obtain a basic and exact information of the ice, surveys of ice conditions and ice properties were performed. Field measurements for five winters showed that the lake is usually ice covered for about three months, and the ice thickness often reaches to 50 cm. The cover consists of many layers of snow ice and saturated snow and a black ice at the bottom of the ice cover. A numerical model for predicting the growth of ice cover was established and calculated ice thickness was preferably compared with observed ice thickness. Testings of compressive strength and flexural strength resulted in relationships between strength and air content in ice. In spring large ice movements and ice ride ups on shore were observed. Analysis of ice movements observed on March 16,1987 revealed a size of horizontal ice load possible in this lake. As a conclusion, possible effects of ice and a criteria for ice forces on hydraulic structures in this Lake with rather mild climate conditions were clarified.
Year: 1988