EXPERIMENTAL STUDY ON ACCUMULATION AND FAILURE OF DRIFTWOOD JAM AND INCREASE IN DARG FORCE ON BRIDGE PIER

Abstract

 We conducted the driftwood accumulation tests to investigate the formation of driftwood jam behind one bridge pier by changing the wood length. We examined the length in the streamwise and vertical directions and width of driftwood jam. The sink ratio of incoming wood pieces was also measured. Next, we measured the drag force exerted on the bridge pier and evaluated the increase in drag force and drag force coefficient of bridge pier due to driftwood accumulation. Finally, we focused on the failure of driftwood jam. We measured the times series of drag force when the vibration of jam occurred and examined the change of jam size before and after the failure.