Author(s): Shiro Maeno; Keisuke Yoshida; Ryuji Tanaka
Linked Author(s): Keisuke Yoshida
Keywords: High flood discharge; Driftwood hazard; Fluid force on the bridge; 3D flow analysis
Abstract: Very heavy rains on July 28 2013 in Yamaguchi and Shimane prefectures caused severe damage to bridges. The extremely high flood discharge, coupled with the accumulation of large amounts of driftwood (logs, branches, and rootstock) caused the failure. This study examined the possibility of assessing the forces acting on a bridge using three-dimensional flow analysis in comparison with experimentally obtained results. Then hydrodynamic forces acting on the bridge under different water level conditions with or without driftwood accumulation were investigated. Numerical results show that the force acting on the bridge can be estimated using a three-dimensional flow simulation. Results clarified that the force acting on the bridge under an overflow condition of the bridge in a driftwood-accumulated state is 10 times greater than the force exerted in an ordinary flood discharge state.