EXPERIMENTAL STUDY ON THE EFFECT OF DRIFTWOOD CATCHMENT ON SCOURING AND ACCUMULATION AROUND PIERS

Abstract

 Recently, the river infrastructure and channel have been damaged by driftwoods flowed out during floods induced by heavy rain in Japan. The previous studies on local scouring around bridge piers have been conducted for a long time, but there is few research focusing on driftwood catchment. In this study, we aim to clarify the effect on the local scour/accumulation around the pier by changing the driftwood capture conditions (installation height and density) by conducting a small model experiment. As a result, it was found that when the height of driftwood installation is near the bottom and the density of driftwood is high, the effect of scouring is shown. Moreover, we proposed "annular riprap work" considered driftwood catchment condition as a new scour countermeasure. The construction range of the countermeasure work was narrower than that of the conventional countermeasure work, and it was confirmed that the scouring resistance was higher than that when trapping driftwood.