Determination of Rectangular Collar Dimensions for Reducing Scour Around Bridge Pier

Document Type : Research Paper

Authors

Abstract

Different methods have been proposed to prevent or reduce scouring around bridge piers. Making use of collars as countermeasures has recently been noticed by researchers. Collar dimensions have great impact on reducing local scour around bridge piers. This study showed that rectangular collars around circular piers reduced both intensity of scouring and depth of scour hole. In this study the effects of collar length in up and down-stream of the pier model and also on its width were investigated. The dimensionless length of rectangular collar in upstream (Lu/D) and downstream (Ld/D) found to be 0.92 and 1.42, respectively, and the width of collar was estimated 3 times greater than the pier diameter. It is noteworthy to mention that with these dimensions scouring process was rarely observed around the pier model after elapsing 62 hours.

Keywords

Main Subjects


ارونقی ه، حسین زاده دلیر ع، فاخری فرد الف و فرسادی زاده د، 1385. بررسی آزمایشگاهی تاثیر دیواره­های جانبی کانال بر روی عمق حفره آبشستگی اطراف پایه­های پل. مجله دانش کشاورزی، جلد 16، شماره 2. صفحه­های 1 تا 11.
پارسابصیر ه، چمنی م و زراتی الف، 1383. حفاظت پایه­های پل در مقابل آبشستگی موضعی با استفاده توام از سنگچین و طوق.پایان نامه کارشناسی ارشد، دانشکده مهندسی عمران، دانشگاه صنعتی اصفهان، اصفهان، 127 صفحه. 
شفاعی بجستان م، 1373. هیدرولیک رسوب. انتشارات دانشگاه شهید چمران اهواز.
زراتی الف و عزیزی م، 1376. بررسی روشهای کنترل و کاهش آبشستگی پایه­های پل. صفحه­های 261 تا 267. مجموعه مقالات اولین کنفرانس هیدرولیک ایران. 11 - 13 شهریور، دانشگاه تهران، تهران.
Breusers NHC and Raudkivi AJ, 1991. Scouring. 2nd hydraulic structures design manual. Balkema, Rotterdam, The Netherlands.
Chiew YM, 1992. Scour protection at bridge piers. J Hyd Eng ASCE, 118( 11): 1260-1269.
Dargahi B,1987. Flow field and local scouring around a cylinder. Bullten  No.137 . R Inst Tech Hydr Lab Stockholm ,Sweden.
Ettema R, 1980. Scour at bridge piers. Report No.216, University of Auckland, New Zeland.
Laursen EM and Toch A,1956. Scour around bridge piers and abutments. Iowa Highway Research Board, Bulletin 4, Bureau of Public Roads, Iowa.
Melvill BW, 1997. Pier and abutment scour : Integrated approach. J Hyd Eng ASCE, 132 (2) : 125-136.
Melvill BW and Chiew YM, 1999. Time scale for local scour at bridge piers. J Hyd Eng ASCE, 125 ( 1) : 59-65.
Muller DS,1996. Local scour at bridge piers in nonuniform sediment under dynamic conditions. Ph.D dissertation, Department of Civil Engineering, ColoradoStateUniversity.
Neill CR, 1973. Guide to bridge hydraulics. University of Toronto press, Toronto, Canada.
Sheppard DM and Miller Jr W, 2006. Live-bed local scour experiments. J Hyd Eng ASCE, 132 (7) : 635-642.
Thomas Z, 1967. An interesting hydraulic effect occurring at local scour. Pp.125-134  Proceeding of the 12th IAHR Congress. September 11-14, Colorado, USA.