مقایسه دو آرایش مثلثی و خطی شمع‌های فداشونده مستغرق بر عمق آبشستگی اطراف پایه پل استوانه ای

نوع مقاله: مقاله پژوهشی

نویسندگان

1 دانشیار بخش مهندسی آب، دانشگاه شیراز

2 کارشناس ارشد سازه‌های آبی، بخش مهندسی آب، دانشگاه شیراز.

3 کارشناس ارشد سازه های آبی، بخش مهندسی آب، دانشگاه شیراز.

چکیده

کنترل آبشستگی موضعی اطراف پایه‌ها و نیم پایه‌های پل‌ها به دلیل خسارات وارده به پل­ها از اهمیت زیادی برخوردار است. در همین ارتباط در این پژوهش با بکارگیری گروه شمع‌های فدا شونده در دو آرایش مثلثی پنج تایی و هم­چنین خطی سه ‌تایی به‌صورت غیر مستغرق و مستغرق با چهار نسبت L/y برابر با 4/0، 6/0، 8/0 و یک به بررسی آبشستگی موضعی پایه پل پرداخته‌شده است. نتایج حاصل از 12 آزمایش انجام شده نشان می­دهد که با افزایش نسبت L/y در هر دو آرایش مثلثی و خطی عمق آبشستگی کاهش می‌یابد به‌گونه‌ای که در آرایش مثلثی در نسبت L/y برابر  8/0 بیشترین کاهش در عمق آبشستگی به میزان 6/44 درصد مشاهده شد که این کاهش عمق در آرایش خطی در نسبت L/y برابر یک به میزان 8/30 درصد می‌باشد هم­چنین شمع‌های فداشونده غیر مستغرق تأثیر بیشتری در کاهش آبشستگی نسبت به شمع‌های مستغرق نشان دادند که این میزان کاهش در آرایش مثلثی بیشتر و  به میزان 2/49 درصد مشاهده شد.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Comparison of Linear and Triangular Arrangements of Submerged Sacrificial Piles on Local Scour Depth around Cylindrical Bridge Piers

نویسندگان [English]

  • Seyed Mohammad Ali Zomorodian 1
  • Hamideh Ghafari 2
  • Zahra Ghasemi 3
1 Associate Professor of Water Engineering, Shiraz University, Iran.
2 MSc of Student Hydraulic Structure, Water Engineering Department, Shiraz University, Iran.
3 MSc Student of Hydraulic Structure, Water Engineering Department, Shiraz University, Iran.
چکیده [English]

The control of local scour around the piers and bridge abutments has been recognized as an issue of considerable importance due to the structural damage of bridges. Many methods have been already proposed by several researchers to tackle this problem, including methods that change the pattern of flow around the piers, such as sacrificial piles (Melville and Hadfield, 1999; Chabert and Engeldinger, 1956), Submerged vanes (Lauchlan, 1999; Grimaldi et al., 2009a), Slot (Chiew, 1992; Grimaldi et al., 2009b), and collars (Zarrati et al., 2006; Alabi, 2006). In addition to the above methods, other methods have been developed to protect the bed against the scour, including the use of riprap around the pier (Parola, 1993; Graziano et al., 1990), sandy bags, gabions, and geotextiles. The sacrificial piles are, indeed, the piers with smaller diameters than the bridge piers, which divert the flow from the bridge pier leading to the reduction of the scour potential. The efficiency of the sacrificial piles in controlling the scour depends on the number and diameter of the piles, the degree of submergence, the arrangement, their relative  placement against the piers, the distance between the piles, the distance between the piles and the piers as well as their angles to the flow (Melville and Hadfield, 1999). According to these methods, many studies have been carried out on the effect of the sacrificial piles in reducing the bridge piers scour. However, the use of submerged piles with different degrees of submergence has been less considered. Since the length of sacrificial piles has an effect on the degree of submergence, the length of the sacrificial piles is effective in scouring, as well. In effect, the present study focuses on the scouring around bridge piers by using 2 different arrangements with and without using the sacrificial pile groups at the upstream of the pier.

کلیدواژه‌ها [English]

  • Local scour
  • Bridge pier
  • Submerged Sacrificial piles
1- Alabi, P.D., 2006. Time development of local scour at a bridge pier fitted with a collar. Master Degree Thesis. University of Saskatchewan, Saskatoon, Saskatchewan, CA.

 

2- Chabert, J. and Engeldinger, P., 1956. Etude des affouillements autour des piles des ponts. Study on scour around bridge piers, Laboratoire National d’Hydraulique, Chatou, France (in French)

 

3- Chiew, Y.M. and Mellville, B.W., 1987. Local scour around bridge piers. Journal of Hydraulic Research, 25(1), pp. 15-26.

 

4- Chiew, Y.M., 1992. Scour protection at bridge piers. Journal of Hydraulic Engineering, 118(9), pp. 1260–1269.

 

5- Graziano, F. G., Jones, J. S. and Parola, A. C., 1990. Design of riprap to protect bridge Piers from local scour. Journal of Highway Research and Development, Public Roads, 54(2), pp. 193–199.

 

6- Grimaldi, C., Gaudio, R., Calomino, F. and Cardoso, A.H., 2009a. Control of scour at bridge piers by a downstream bed sill. Journal of Hydraulic Engineering, 135(1), pp. 13–21.

 

7- Grimaldi, C., Gaudio, R., Calomino, F. and Cardoso, A.H., 2009b. Countermeasures against local scouring at bridge piers: Slot and combined system of slot and bed sill. Journal of Hydraulic Engineering, 135(5), pp. 425–431.

 

8- Haidari, M., Saneie, M., Hajikandi, H. and Behzadniya, E., 2011. Laberatory Investigating of using Submerged Sacrificial Piles on reducing scour in the spur dike. In 6th National Congress on Civil Engineering, Semnan University, Semnan, Iran. (In Persion).

 

9- Haque, M. A., Rahman, M. M., Islam, G. M. T. and Hussain, M. A., 2007. Scour mitigation at bridge piers using sacrificial piles. Journal of Sediment Research, 22(1), pp. 49-59.

 

10- Lauchlan, C.S., 1999. Pier scour countermeasures. PhD Thesis, University of Auckland, Auckland, NZ.

 

11- Melville, B. W. and Hadfield, A. C., 1999. Use of sacrificial piles as pier scour countermeasures. Journal of Hydraulic Engineering, ASCE, 125(11), pp.1221-1224.

 

12- Parola, A. C., 1993. Stability of riprap at bridge piers. Journal of Hydraulic Engineering, 119 (10), pp. 1080–1093.

 

13- Pirayesh, A., Saneie, M. and Kolahchi, A.A., 2012. Effects of changes in pile distance from the abutment upstream on reduction of local scour. In 6th International Conference on Scour and Erosion, ICSE6-288, Paris.

14- Raudkivi, A.J., 1998. Loose Boundary Hydraulics. A. A. Balkema, Rotterdam, the Netherland.

 

15- Raudkivi, A.J. and Ettema, R., 1983. Clear-water scour at cylindrical piers. Journal of Hydraulic Engineering, 109(3), pp. 338–350.

 

16- Razmi, M.M., Saneie, M. and Ershadi, S., 2013.  The effect of percentage of submergence of Sacrificial Piles on reducing scour in the bridge aboutment. In 7th National Congress on Civil Engineering, Sistan and Baluchestan University, Zahedan, Iran. (In Persion).

 

17- 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, 132(2), pp. 154–162