Countermeasures Against Local Scouring Around Bridge Abutments: Combined System of Collar and Slot

An important issue in river engineering is to control scour around bridge piers and abutments using either a collar or a slot. This study examines the use of a slot or a collar, either alone or in conjunction with one other, to reduce scour at bridge abutments. In research on abutments equipped with slots only, collars only, and a combination of both were tested 15, 9, and 18 times, respectively. According to the results, in abutments equipped with slots only, the closer the slot is to the channel wall, the better the performance. At the same time, according to the results of research on collars, mere protection of the upstream face of the abutment is not sufficient to prevent down flows due to the presence of horseshoe and wake vortices, but the downstream faces of collars play a substantial role in reducing scour. With an increase in collar length, the scour depth decreases and the scour hole shifts downstream farther away from the abutment. Finally, it was found that the slot-collar combination model takes a more proactive role in reducing scour compared to collars only or slots only. The most robust combinatorial model used managed to fully control scour around abutments. For combinatorial models, scour showed a 42-100% decrease under different flow conditions in an erodible bed.

Automated summary

The study found that in abutments equipped with slots only, the closer the slot is to the channel wall, the better its performance. Research on collars showed that protecting only the upstream face of the abutment is not enough to prevent down flows due to horseshoe and wake vortices, but the downstream faces of collars play a significant role in reducing scour. The combination of a slot and a collar was found to be more effective in reducing scour compared to using collars or slots alone.