Author(s): Tae Hoon Yoon
Keywords: No Keywords
Abstract: The presence of hydraulic structures such as bridge piers will cause the change of flow round the piers, which is resulted in local scour around the piers. The local scour at the piers has been a perplexing problem to endanger the stability of the bridge piers. In order to resolve the problem, numerous scour countermeasures have been introduced. They are classified in two groups: armoring countermeasures and flow altering countermeasures. The former is to withstand the increased erosive forces of flow occurred around a bridge pier due to a hydraulic condition by acting as a resistant layer to hydraulic shear stresses providing protection to the more erodible materials underneath. They include ripraps, wire gabions, cable-tied concrete blocks, tetrapods, etc. And the latter is to deflect the approaching flow or to divert downflow for reduced plucking power of flow. Collars and slots shield bed material from the downflow and horseshoe vortices. Meanwhile group piles, vegetation zone, and sacrificial piles protect the pier from scouring by suppressing the approaching bed forms, causing a wake region downstream resulting in weakened entraining forces of the flow, and deflecting the high velocity flow, respectively.