洪水時の急勾配中小河川の橋梁に作用する流体力の評価

抄録

Very heavy rain on July 28th in 2013 in Yamaguchi and Shimane prefectures caused severe damages of bridges. It is considered that not only the extremely high flood discharge but also accumulation of large amount of driftwoods caused the failure. In this study, at first possibility of obtaining a force acting on the bridge using three-dimensional flow analysis was examined. Then hydrodynamic forces acting on the bridge under different water level condition and with or without driftwoods accumulation were also investigated. The numerical results show that the force acting on the bridge can be estimated using three-dimensional flow simulation. And it is clarified that the force acting on the bridge under over flow condition of bridge with driftwoods accumulated state increases ten times larger than ordinary flood discharge state