Reduction of local scour around bridge abutments with collars

摘要

Estimation of the depth of scour at bridge foundations is a problem that has perplexed designers for many years. In this study, an investigation on the reduction of scour around bridge abutments using rectangular collars was carried out for clear-water flow over uniform sediment particles. The primary cause of local scour around a bridge abutment is the presence of vortex flow called the principal vortex. The growth of vortex can be arrested by forming a rigid surface around the abutment with a collar plate. The primary objective of this study is to determine the scour reduction of collars of different sizes at different elevations for abutments. Experimental results showed that a collar plate placed on the abutment at the bed level reduces the maximum scour depth by 45% in comparison to an unprotected abutment. However, in the eventuality of lowering or rising the collar with reference to the sand bed, its efficiency depends on the abutment's width and length.