Reduction of local scour around a circular bridge pier using the collars and sacrificial piles in non-uniform sediment
Year: 2024
Type: article
Abstract: In the present study, circular and octagonal collars together with sacrificial piles are tested for their efficiency as protection devices against local scour in the non-uniform sand bed of geometric standard deviation 2.29 and median grain size 1.18 mm. To examine the effect of width and elevation on scour depth , experiments are conducted with circular and octagonal collars of widths 1.5 b and 2 b placed on the bed and 0.25 y above the bed where b is the pier diameter and y is the flow depth. The octagonal and circular collars of width 2 b placed in flush with the bed achieved maximum scour reductions of 78.33 % and 75 %, respectively. The efficiency of the collars decreased when their width is reduced and when they are placed above the bed. Among the sacrificial piles in transverse and staggered arrangements , a maximum scour reduction of 55 % is observed when the piles are placed transverse to the flow at a distance of 2 b from the pier center. The efficiency of the sacrificial piles decreased when they are moved away from the pier center. A maximum scour reduction of 86.67 % is seen for the combination of the octagonal collar of width 2 b on the bed and piles in the transverse arrangement. A new empirical equation is proposed for temporal and equilibrium scour for collar around the pier, including the armor effects. The sensitivity analysis revealed that b c / b is the most sensitive parameter followed by H / y , k s and T c where where b c is the collar width, H is the location of the collar from the water surface , k s is the shape factor and T c is dimensionless time .
Source: Geomorphology
Language: English
Subfield: Ecology
Field: Environmental Science
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $3,300
Award: G5433051374
OpenAlex ID: W4401689053