Effect of Netted Collar on Local Scouring around the Bridge Cylindrical Pile Groups

Document Type : Research Paper


department of water structure engineering, faculty of water sciences engineering, sahahid chamran university of ahvaz, ahvaz, iran


The problem of scouring the piers of bridges which has attracted the attention of the specialists of
hydraulic sciences for decades. So far, various methods have been proposed to prevent scouring
that using netted collar is one of these methods. In this research, the effect of the presence of
netted collar on scouring of the bridge cylindrical pile group at clear flow conditions has been
investigated. For this purpose, a flume with length of 6m and width of 73cm was used and the
effect of the collars of 0, 30, 50 and 70 percentage of the netted was tested at the levels of 0.5D
above the bed (D is the pier diameter) and on the bedduring 9 experiments. On the bed level, all collars had high efficiency and the 30-percent of opening could to control the scour around the first pier
completly. At the level of 0.5D, the 30 percent netted collar reduced the scour depth by 58
percent, While the efficiency of 0, 50, and 70% Netted Collars at this level were 4, 0 and 15 percent, respectively. In general, with the reduction of collar level, efficiency was increased.


Main Subjects

  • Receive Date: 16 April 2018
  • Revise Date: 10 November 2018
  • Accept Date: 27 November 2018
  • Publish Date: 13 May 2019