FACTOR ANALYSIS AND RISK ASSESSMENT OF BRIDGE DAMAGES AT TAKESHI RIVER AND YOJI RIVER BY TYHOON NO. 19 IN 2019

Abstract

 Typhoon No. 19, which occurred on October 6, 2019, caused a lot of bridge damages resulted by revetment damages in Chikuma River in Shinano River system. It is expected that the risk of the bridge damage can be predicted in advance and the countermeasures can be considered by clarifying the factors that cause the bridge damage to such floods. On the other hand, most of the previous studies have focused on the scour damage, and there have been few cases of damage to the revetments. The purpose of this study is to analyze the factors of 30 bridge damages caused by Typhoon No. 19 in 2019 in Takeshi river in Ueda city and Yoji river in Sakuho town where are the largest number of the bridge damages, and to clarify the parameters useful for determining the presence or absence of damage to the bridge with the revetments based on the linear discriminant analysis. The results showed that, as in previous studies, the influence of parameters such as the year of bridge construction and water depth was significant. In addition, the number of span, the degree of bending, the bridge health, and the cross-sectional shape of the river were also found to affect bridge damage.