| Co-Investigator(Kenkyū-buntansha) |
SAKURADA Ryoji AKITA NATIONAL COLLEGE OF TECHNOLOGY, DEPARTMENT OF CIVIL ENGINEERING, A/PROFESSOR, 環境都市工学科, 助教授 (60290699)
HASEGAWA Takeshi AKITA NATIONAL COLLEGE OF TECHNOLOGY, DEPARTMENT OF SCIENCE, PROFESSOR, 自然科学系, 教授 (10004409)
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| Research Abstract |
This research project aims to investigate the characteristics of freezing indices and regional disasters related to freezing-thawing phenomena in snowy and cold regions in Japan. For this purpose, field test apparatus was installed at the site of public road to observe the variations of underground temperature through the year, then the laboratory testings of the soil samples used for new building road were carried out to distinguish the geomaterials for preventing freezing-thawing henomena. On the other side, various kind of winter meteorological data were collected and analysed. From the data analyses, several new information were obtained as follows : (1) Freezing index is getting lower in recent years. This phenomenon corresponds to the recent warming winter tendency that was verified by this research in analyzing the time series data. (2)Winter temperature is getting higher within the recent half century, that is, 3℃ up in Sapporo, 1.5℃ up in Akita, and 1.5℃ up in Fukui. In this way, warming winter tendency was recognized clearly in high latitude. (3) According to the spectrum analysis of daily minimum air temperatures, superior periodicity was found as 11- year in Sapporo, and 9- year at the basin areas in Honshu island. (4)Freezing indices distribution map of Tohoku district was made for the winter of 2000/2001. We found a new relationship between the freezing index, elevation from the sea level, and freezing depth. In which, each prefecture has an independent coefficient of the distribution equation. However, proposed equation on freezing index was not followed well especially in the heavy snow cover areas because of its effectiveness of snow insulation.
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