Mitigation of local scour around a trapezoidal bridge abutment using sacrificial piles

Scour poses a significant threat to the stability of bridge piers and abutments. This study investigates the effectiveness of sacrificial piles as a countermeasure to reduce scour around bridge abutments through laboratory experiments. The abutment was modelled in a trapezoidal shape, common in Pakistan, with circular sacrificial piles positioned upstream. The aspect ratio (AR) of the pile group varied between 0.75, 1.00, and 1.70, with the spacing between cylinders (G/d) set at 1.5, 2.14, and 2.84. Optimal scour reduction (40.26%) was achieved when the distance between piles and the abutment was increased up to six times the abutment width. The highest scour reduction (70.13%) occurred with a dense pile configuration (G/d = 1.5) and an AR of 0.75. The study also proposes a regression-based predictive equation and sensitivity analysis to estimate scour depth around bridge abutments in open flume conditions.