Author(s): M. Heidarpour; H. Afzalimehr
Linked Author(s):
Keywords: Scouring; Bridge group pier; Scour reduction; Collar
Abstract: Local scouring is one of the most important causes of bridge failure. Therefore, there is an interest in finding reliable ways to reduce and control local scour depth and, thereby, requisite pier embedment depth. Collar is one of the flow-altering devices that have been used to protect piers against local scour. The scour-reduction performance of a collar on a single pier has already been established in earlier studies. When the scour process is due to the presence of pier groups, some mechanisms such as reinforcing, sheltering and shed vortices occur that make the phenomenon more complex. Furthermore, the group effects will alter with changes in pier spacing. This study addresses the effectiveness of using collar on the pier groups at clear water condition. The models consist of two and three circular-shaped piers aligned to the flow with diameter of 0. 02m and pier spacing of three and four times the pier diameter. The collars diameter was twice and three times the pier diameter. The results showed that the efficacy of a collar for a single pier can not be applied for piers in a group pier. Also, the results indicated that installing of the collar on rear piers in a pier group is more effective than the front piers. Changing the pier spacing and the size of collar has significant influence of rear piers and minor effect on front piers.
Year: 2005