MODEL EXPERIMENT AND 3D FLOW SIMULATION FOR INFLUENCE OF CAPTURED DRIFTWOOD ON FLUID FORCE OF RIVER BRIDGE

Abstract

 River bridges under flood flows have been sometimes washed away frequently due to the occurrence of excess flood and the capture of driftwood on the bridge girder. The purpose of this study is to clarify the effect of caputured driftwood on the fluid forces on the bridge girder by conducting a model experiment and a 3D flow simulation. The result shows that the fluid force on the bridge girder increased sharply even with a slight increase in the flow rate due to the captured driftwood. In addition, the larger the amount of captured driftwood, the greater the fluid force acting on the bridge girder, and the increase in the projected area contributes most to this. 3D flow simulation indicates that flow structure around the bridge girder with captured driftwood are mostly examined.