نوع مقاله: مقاله پژوهشی
نویسندگان
1 دانشجوی کارشناسی ارشد سازه های آبی گروه مهندسی آب دانشگاه گیلان
2 استادیار گروه مهندسی آب دانشگاه گیلان
چکیده
کلیدواژهها
عنوان مقاله [English]
نویسنده [English]
One of the most important issues in scour depth at bridge piers is effect of debris raft which convened by flood and by blocking all or a part of the bridge opening, changes the flow pattern and increases the maximum scour depth around bridge pier considerably. In this paper, the effect of debris dimensions on a maximum scour depth around vertical bridge pier groups was investigated. The studied bridge piers consisted of two rectangular piers with 2.5×3.5 cm dimensions, which installed on the foundation with 10cm × 16cm width and length, respectively. The experiments performed consisted of relative depth (the depth to width pier ratio) 3.7, 5.2 and 6.6, debris relative width (the debris width to pier width ratio), 6, the relative length (debris length in flow direction to pier width), 2 and 3, the relative thickness (debris thickness to pier width), 0.5 and 1 and different levels of foundation. All experiment conducted under clear water condition. Comparison of results indicated that increase of flow depth did not considerably affect the local scour depth. By increasing debris relative thickness, the maximum scour depth increased about 42% in comparison with no debris raft. Furthermore,with increase of relative debris length, the effect reduced and increase of the maximum scour depth reached up to 17%. As compared to without debris raft condition. Comparison of results indicated that by increasing the level of foundation, increase of the maximum scour depth was more in presence of debris raft.
کلیدواژهها [English]
Ataie-Ashtiani, B. and Beheshti, A. A. 2006. Experimental investigation of clear-water local scour at pile groups. J. Hydraul. Eng. 132(10): 1100-1104.
Breusers, N. H. C. and Raudkivi, A. J. 1991. Hydraulic Structure Design Manual: Scouring. Vol. 2. Balkema, Rotterdam, Netherlands.
Esmaeili-Varaki, M., Mosapoor, S. and Hatam-Jafari, M. 2013. Exprimental study the effect of geometric factors on local scour characteristics around inclined bridge pier groups with foundation. Iranian Water Res. J. 7(13): 141-151. (in Persian)
Fallah-Golneshini, N., Zahiry, A., Meftah-Halghi, M. and Dehgheni, A. 2012. Exprimental study the effect of water depth on maximum scour bridge pier under present of debris accumulation condition. The First International Conference and the 3rd National Conference on Dames and Hydropower. Tehran, Iran. (in Persian)
Ferraro, D., Tafarojnoruz, A., Gaudio, R. and Cardoso, A. H. 2013.Effects of pile cap thickness on the maximum scour depth at a complexpier. J. Hydraul. Eng. 139(5):482-491.
Hannah, C. R. 1978. Scour at pile group. Research Report.No.78. University of Canterbury. Civil Engineering.
Jones, J. S., Kilgore, R. T. and Mistichelli, M. P. 1992. Effect of footing Location on bridge pier scour. J. Hydraul. Eng. 118(2): 280-290.
Lagasse, P. F., Zevenbergen, L. W. and Clipper, P. E. 2010. Impacts of debris on bridge pier scour. International Conference on Scour and Erosion (ICSE-5).
Laursen, E. M. and Toch, A. 1956. Scour around bridge piers and abutments. Bulletin No. 4. Iowa Highway Research Board.
Lyn, D. A., Cooper, T. J., Yi, Y., Sinha, R. N. and Rao, A. R. 2003. Debris accumulation at bridge crossing. Laboratory and Field Studies. Rep. No. FHWA/IN/JTRP/10. West Lafayette, IN 47906.
Melville, B. W. and Chiew, Y. M. 1999. Time scale for local scour at bridge piers. J. Hydraul. Eng. 125(1): 59-65.
Melville, B. W. and Dongol, D. M. 1992. Bridge pier scour with debris accumulation. J. Hydraul. Eng. 118(9): 1306-1310.
Melville, B. W. and Sutherland, A. J. 1988. Design method for local scour at bridge piers. J. Hydraul. Eng. 114(10): 1210-1226.
Moreno, M., Maia, R. and Couto, L. 2015. Effects of relative column width and pile-cap elevation on local scour depth around complex piers. J. Hydraul. Eng. 142(2): doi: 10.1061/(ASCE)HY.1943-7900.0001080.
Moreno, M., Maia, R. and Couto, L. 2016. Prediction of equilibrium local scour depth at complex bridge piers. J. Hydraul. Eng. 142(11): doi: 10.1061/(ASCE)HY.1943-7900.0001153.
Moshashaei, S. M., Asadi-Aghbalagi, M. and Samadi-Brojeni, H. 2015. Study the effect of accumulation of wood floating in front of the circle pier with pile. J. Water Soil. 25(2): 141-153. (in Persian)
Pagliara, S. and Carnacina, I. 2010. Scour and dune morphology in presence of large wood debris accumulation at bridge pier. Riverflow- International Conference on Fluvial Hudraulics. Braunschweig, Germany.
Pagliara, S. and Carnacina, L. 2011. Influence of wood debris accumulation on bridge pier scour.
J. Hydraul. Eng. 137(2): 254-261.
Parola, A. C., Mahavadi, S. K. Brown, B. M. and Khoury, A. E. 1996. Effects of rectangular foundarion geometry on local pier scour. ASCE-J. Hydraul. Eng. 122(1): 35-40.
Raudkivi, A. J. and Ettema, R. 1983. Clear-water scour at cylindrical piers. J. Hydraul. Eng. 109 (3):
339-350.
Vittal, N., Kothyari, U. C. and Haghghat, M. 1994. Clear-water scour around bridge pier group. J. Hydraul. Eng. 120(11): 1309-1318.
Zarati, A. R. 2000. Role of Hydraulic Factor in Bridge Design. Hormozgan University Press. First Ed.
(in Persian)
)