大源太川第1号砂防堰堤の老朽化調査に基づく補強対策工の基本設計

抄録

Daigentagawa sabo dam No. 1 was built at inlet zone of a gorge of the Daigenta river, which is a tributary of Uono river included in the Shinano river water system. This mortar masonry arch-shaped sabo dam was built of rubble mixed lean concrete and took one and a half years to complete from when its construction was started in 1938. It is one of early arch-shaped sabo dams among other existing ones in Japan. Agency for Cultural Affairs in Japan designated it as a registered tangible cultural property, and moreover, it also attracts many visitors. Whereas, some problems have been found recent years, such as water leakage, because many years have passed since it was constructed. For this reason, a decrepit research of the dam was conducted to examine the condition inside of the dam built of rubble mixed concrete and its strength. Following the result, stability verification by finite element method analysis was conducted. The result revealed it did not keep enough stability. Therefore, a countermeasure for the dam reinforcement was designed with physical property values that had been obtained from the research. In this paper, we report what we examined and learnt from the decrepit research of the dam constructed long time ago but also the study of basis countermeasure design for its reinforcement.