Investigation of collar in different sizes and bed level as a bridge abutment scour countermeasure

摘要

In this research, an investigation related to the reduction of scour around a vertical-wall bridge abutment using rectangular collar has been carried out for the case of clear-water flow condition over uniform sediment particles. The primary cause oflocal scour around abutment is a spiraling vortex flow structure called the principal vortex. The growth of the vortex can be arrested by retaining the vortex on a rigid surface by a collar plate, and therefore, the excessive scouring around the bridge abutment can be prevented. The primary objective of this study is to determine the time varying development of scouring around the bridge abutment by using collars of different sizes and at different elevations. Development of scouring with and without collar was studied and observed scouring values were compared to each other. Experimental results showed that in addition to reduction of scour depth, a collar was very effective in reducing the rate of temporal development of the scour hole