Assessment the local scour around vertical and inclined oblong piers under shallow flow condition

Abstract

Scour around abutment and piers of water structures cause a failure for these structures in most developing countries. Most of the existing scour prediction equations are mainly produced for circular and square piers. However, in reality, many bridge piers behave as oblong piers (round noses). The dimensionless maximum scours depths (ys/D) were extensively investigated for ten pier configurations under shallow flow operating conditions. The length-to-width (L/D) ratio was optimized for the development of the scour hole around inclined and vertical oblong piers. The ys/D depths around vertical and inclined oblong piers are slightly affected by the L/D ratios in contrast to rectangular piers. However, the ys/D value was reduced by values of 5.9–11.6% around the oblong piers compared to the circular one. Furthermore, the appropriate prediction equations were assessed for determining the maximum ys/D for different pier configurations. CSU and Vagfhi equations are modified to give an accurate prediction for the maximum ys/D around vertical and inclined oblong piers, respectively.