Simultaneous Effect of Collar and Roughness on Reducing and Controlling the Local Scour around Bridge Abutment

Abstract

Investigation of local scour around hydraulic structures particularly bridges is of crucial importance in river engineering. Bridge destruction mostly occurs as a result of scour phenomenon around piers and abutments, not because of structural weaknesses. Hence, finding a solution to reduce scour depth is momentous. In this study which was conducted in the conditions of clear water scour, the effect of local roughness and collar and also impact of using them simultaneously around bridge abutment were evaluated. The results demonstrated that the existence of roughness causes a reduction in the severity of scouring process and its final depth and the use of collar leads to a delay in the scouring process in addition to the ultimate reduction in the scour depth, which in case of using them simultaneously, scour depth decreases by about 83%.

Reducing Scour around Semi-Elliptical Bridge Abutments: Application of Roughness Elements

“…The choice of a 20 cm thickness for the bed material was based on the consideration that the maximum scour depth was equal to 2.4 times the abutment length (L). While it is possible to increase the thickness by 30%, a 20 cm thickness was selected for the bed material [13][14][15]. The data collection for all experiments took place once the flow in the flume reached its fully developed state at 9.75 units from the entrance.…”

“…This diagram takes into account sediment particles with an average size of 0.95 mm. Additionally, the logarithmic law of velocity distribution (Equation ( 1)) was employed to determine the critical velocity and flow depth [15]. These approaches were used to ensure accurate determination of the necessary flow conditions for scour in the experiment.…”

Dam-Break Energy of Porous Structure for Scour Countermeasure at Bridge Abutment

“…Time factor is crucial to predict this long duration process. However, time factor are mostly proposed for single pile and pipeline, limiting the application effectiveness in pile groups [5,13]. They focus on scour under threshold velocity intensity and cannot be directly applied in live bed condition.…”

“…Although the porous materials were improved when compressed under densification, strain energy is almost as dynamic. Previous studies have been conducted to countermeasure the scouring [4][5][6][7][8][9]. stated that the scour is not confined to the structure; the strength and durability of the structure get into it [8].…”

“…stated that the scour is not confined to the structure; the strength and durability of the structure get into it [8]. Furthermore, Shahsavari et al (2021) found that the scouring will cause problems when the subsidence of the riverbed causes instability or failure of structures located on or close to the river [5].…”