کاربرد همزمان سنگچین و المان های شش پایه در کنترل عمق آبشستگی اطراف تکیه گاه پل مستطیل شکل

نوع مقاله: مقاله پژوهشی

نویسندگان

1 دانشجوی دکتری سازه های آبی،دانشکده مهندسی علوم آب، دانشگاه شهید چمران اهواز.

2 استاد گروه سازه های آبی، دانشکده مهندسی علوم آب، دانشگاه شهید چمران اهواز

3 استاد گروه سازه‌های آبی، دانشکده مهندسی علوم آب، دانشگاه شهید چمران اهواز

چکیده

تخریب پل­ها در اثر عوامل مختلفی چون بروز آبشستگی در تکیه­گاه آن هر ساله خسارت­های زیادی به بار می­آورد. به­همین دلیل روش­های مختلفی برای کنترل این پدیده ارائه شده است. در این تحقیق از روش ترکیبی به­کار­گیری توام سنگچین و المان­های شش­پایه از نوع روش­های مستقیم برای کنترل آبشستگی در تکیه­گاه مستطیلی استفاده شده است. از دلایل مهم این روش در دسترس بودن و ارزان بودن سنگچین هم­زمان با بکارگیری المان­های شش­پایه با آرایش باز با ایجاد ضریب زبری بالا به­عنوان پوشش است. کارگذاری ترکیبی با سه آرایش، یک لایه سنگچین در زیر المان­های شش­پایه، یک ردیف المان­های شش­پایه در بین دو لایه سنگچین و یک لایه سنگچین در بالای المان­های شش­پایه انجام شد. این کارگذاری­ها در سه عمق روی بستر، زیر بستر و در عمق نصف المان­های شش­پایه در زیر بستر صورت گرفت. همچنین سرعت نسبی جریان بین 0.65 تا 0.95 در نظر گرفته شد. نتایج آزمایش­ها تأثیر قابل ملاحظه­ای از ترکیب توأم کارگذاری سنگچین و المان­های شش­پایه را نشان داد. به­طوری­که در اعداد فرود کمتر آرایش و حالتی که نصف المان­ها روی بستر و سنگچین­ها روی آن قرار داده شدند، توانست تا 97 درصد عمق آبشستگی رأس تکیه­گاه و در اعداد فرود بالاتر، آرایش و حالتی که المان­های شش پایه در روی بستر و سنگچین­ها در بین آن­ها قرار گرفته­شد توانست تا 89 درصد عمق آبشستگی راس تکیه­گاه را کاهش دهد.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Investigation of the Effect of Six Legged Concrete (SLC) Elements Combined with Riprap on Scour Depth at Vertical Wall Bridge Abutments

نویسندگان [English]

  • Ali Akbar Hosein Reza 1
  • Mahmood Shafai bajestan 2
  • Mehdi Ghomeshi 3
  • Manoochehr Fathi Moghadam 3
1 Ph.D.Student, Faculty of Water Sciences Engineering, Shahid Chamran University of Ahvaz, Iran.
2 Professor, Faculty of Water Sciences Engineering, Shahid Chamran University of Ahvaz, Iran
3 Professor, Faculty of Water Sciences Engineering, Shahid Chamran University of Ahvaz, Iran.
چکیده [English]

Destruction of bridges caused by scour and other natural phenomenon brings about financial and life losses. Hence, researchers have been studied extensively the scour mechanism and methods of scour countermeasure. Usually scour at bridge occurs both around piers and abutments. Melville (1992)'s study showed that 70 percent of the failure of bridges in New Zealand was due to the abutment scour. Studies conducted on the failure of 383 bridges in the United States showed that in 25% of them the pier scour, and in 72% of them the damage was due to abutment scour (Kayatrak, 2005). The main cause of the abutment scour is due to complex flow vortices which developed around the abutment. Therefore, during the past decades many measures have been developed to protect the bed material against erosion. These techniques can be categorized in two types of covering methods and flow altering techniques. Design guidelines for some of these mitigation techniques can be found in Melville and Coleman (2000). For existing bridges the common practice is to use armoring materials around bridge abutment. Riprap, gabions, rectangular concrete blocks and tetrahedron frames concrete elements are the most effective material for covering and stabilizing the bed around the bridge abutments. In rivers with high flood discharge, the covering material are subject to high flow velocities and therefore large size of rocks have to be used. When the site construction is far away from mountain area or large sizes of the rocks are not available or too costly to transport, other material should be applied. In the present study, a new concrete element-six –legs concrete (SLC)- beside using of smaller size of rocks have been studied to find out the best combination for protecting bridge abutments against scour.

کلیدواژه‌ها [English]

  • Scour
  • Bridge Abutments
  • SLC elements
  • Riprap
1- Barbhuiya, A.K. and Dey, S., 2004. Local scour at abutments: A review. Sadhana, 29(5), pp.449-476.

 2- Bozkus, Z. and Yildiz, O., 2004. Effects of inclination of bridge piers on scouring depth. Journal of Hydraulic Engineering, 130(8), pp.827-832.

3- Cardoso, A.H. and Fael, C.M., 2009. Protecting vertical-wall abutments with riprap mattresses. Journal of Hydraulic Engineering, 135(6), pp.457-465.

4- Chiew, Y. M. 2004. Local scour and riprap stability at bridge piers in a degrading channel. Journal of Hydraulic Engineering, ASCE. 130 (7): 622-634.

 5-    Chiew, Y. and Lim, S., 2003, March. Protection of bridge piers using a sacrificial sill. In Proceedings of the Institution of Civil Engineers-Water and Maritime Engineering, (Vol. 156, No. 1, pp. 53-62). Thomas Telford Ltd.

 6- Coleman, S.E., Lauchlan, C.S. and Melville, B.W., 2003. Clear-water scour development at bridge abutments. Journal of Hydraulic Research, 41(5), pp.521-531.

 7-    Dongol, D.M.S. and Melville, B.W., 1994. Local scour at bridge abutments. Department of Civil Engineering, University of Auckland.

  8- Ghorbani B. and HeidarPour, M. 2004. Control and reduction of scour using combination of sluts and riprap, Research report, Isfahan University of Technology and Shahrekord University, p.112 (In Persian).

 9- Kandasamy, J.K., 1989. Abutment scour. University of Auckland, School of Engineering Report, (458).

 10- Kayaturk, S.Y., 2005. Scour and scour protection at bridge abutments (Doctoral dissertation, Ph. D. thesis, Department of Civil Engineering, Middle East Technical University (METU), Ankara, Turkey).

11- Khademi, Kh and Shafai-Bejestan,M.2015. Investigation of number, location and angel of submerged vane on scour depth at bridge abutment, Journal of Iranian Water Research, Shahrekord University, 15(8): 44-55 (In Persian).

 12- Khozeimenejad, H., Ghomeshi, M. and Shafai-Bejestan, M. 2015. Comparison of performance of symmetric and unsymmetrical rectangular collar on scour reduction at bridge abutments, Journal of Irrigation Sciences and Engineering, 37(2): 10-12(In Persian).

 13- Korkut, R., Martinez, E.J., Morales, R., Ettema, R. and Barkdoll, B., 2007. Geobag performance as scour countermeasure for bridge abutments. Journal of Hydraulic Engineering, 133(4), pp.431-439.

 14- Lagasse, P.F. and Richardson, E.V., 2001. ASCE compendium of stream stability and bridge scour papers. Journal of Hydraulic Engineering, 127(7), pp.531-533.

 15- Laursen, E.M. and Toch, A., 1956. Scour Around Bridge Piers and Abutments (Vol. 4). Ames, IA: Iowa Highway Research Board.

 16-Mansoori-Hafshejani M. and Shafai-Bejestan M.2014. Comparison of the effect of three different depth of placing rocks on the stability of riprap at bridge abutments in a 90 degree bend, Journal of Soil and Water Sciences, Tabriz University, 12(2): 195-204 (In Persian).

 17-Mansoori-Hafshejani M. and Shafai-Bejestan M. 2011. Design of riprap sizing at river bend around the bridge abutment, Journal of Irrigation Sciences and Engineering, 34(4): 35-45 (In Persian).

 18- Mansoori-Hafshejani M. and Shafai-Bejestan M. 2012. Control of scour at river bend using riprap. Journal of Iranian Water Research, University of Shahrekord, 5(9): 73-83 (In Persian).

 19- Melville, B. W., 1992. Local Scour at Bridge Abutments.  Journal of Hydraulic Engineering, ASCE, 118 (4): 615-631.

 20- Melville, B. W and Coleman, S. E., 2000 .Bridge scour. Water Resources Publications, Colorado, USA, 270p.

 21- Melville, B.W., 1997. Pier and abutment scour –an integrated approach. Journal of Hydraulic Engineering, ASCE, 123 (2):125-136.

 22- Melville, B.W., Van Ballegooy, S., Coleman, S.E., and Barkdoll, B. 2007. Riprap size selection at wing-wall abutment. Journal of Hydraulic Engineering, ASCE.133 (11): 1265-1269.

 23- Pagan-Ortiz, J.E. 1991, Stability Of rock riprap for protection at the toe of abutments located at the flood plain Rep. No. FHWA-RD-91-057. Feederal Highway Administration U.S. Dept of Transportation Washington D.C.

 24- Przdwojski, B. 1995. Bed topography and locaul scour in rivers with banks protected by groynes. Journal of Hydraulic Reserch, 33 (2): 257-273.

 25- Richardson, E.V and Davis, S.R., 2001. Evaluating Scour at Bridges (4th Ed.). Federal Highway Administration, Hydraulic Engineering Circular No.18, FHWA NHI-01-001.

 26- Raudkivi, A.J. 1998. Loose boundary hydraulics. 4th Edition. Rotterdam, Brookfield VT, Balkema. P:496.

 27-Saadatneya, M., Khodashenas, S., Saneei, M. and Esmaeilei K. 2010. The effect of spur dike angle on scour depth around the nose of bridge abutment. 8th Int. River engineering Conf. on River Engineering, Shahid Chamran university of Ahvaz, Iran (In Persian).

 28-Sepahvand, K. and Shafai-Bejstan M. 1995. Investigation of scour depth at bridge abutment under the influence of spur dike. M.Sc thesis, Shahid Chamran University of Ahvaz (In Persian).

 29- Shafai-Bejestan, M. 2009. ‘Hydraulic of Sediment Transport “ 2 nd edition, Shahid Chamran UIniversity, S49p.

 30- Simons, D.B., and Lewis, G.L. 1971. Flood protection at bridge crossings. C.S.U. Civil Engineering Rep. No. CER71-72DBS.GL10.prepared for the Wyoming State Highway Dept. in conjunction with the U.S Dept. of Transportation Washington D.C.

 31- Tey C.B. 1984. Local scour at Bridge Abutment. Report No. 329. School of Engineering, University of Aukland, New Zealand, 215p..

 32- Thornton, C.I., Abt, S.R. and Watson, C.C., 2001. Field Assessment of A-Jacks Installation, A Case Study of Brush Creek, Kansas City, Missouri, and Powell Creek, Waukegan, Illinois. In Wetlands Engineering & River Restoration 2001 (pp. 1-8).

 33- Unger, J. and Hager, W.H., 2006. Riprap failure at circular bridge piers. Journal of Hydraulic Engineering, ASCE. 132 (4): 354-362.

 35- Zarrati, A.R., Nazariha, M., and Mashahir, M.B., 2006. Reduction of Local Scour in the Vicinity of Bridge Pier Groups Using Collars and Riprap. Journal of Hydraulic Engineering, ASCE, 132 (2): 154-162.

 36- Zolghadr, M. and Shafai-bejestan, M. 2015. Investigation of scour depth under the influence of different depth of placement and arrangements of A-jacks at bridge abutment. PhD dissertation, Shahid Chamran university of Ahvaz (In Persian)