تعیین عمق و ابعاد بهینه المان‌های زبری بر روی تکیه‌گاه پل برای کاهش میزان آبشستگی

نوع مقاله : مقاله پژوهشی

نویسندگان

1 دانشجوی کارشناسی ارشد، گروه سازه های آبی، بخش مهندسی آب، دانشکده کشاورزی، دانشگاه شیراز، شیراز، ایران

2 عضو هیئت علمی، گروه سازه های آبی، بخش مهندسی، دانشکده کشاورزی، دانشگاه شیراز، شیراز، ایران

3 بخش مهندسی آب دانشگاه جهرم، جهرم، ایران

چکیده

در سال­های اخیر دلیل تخریب بسیاری از پل­ها آبشستگی تکیه­گاه اعلام شده است. تحقیقات بسیاری به کم کردن آبشستگی تکیه­گاه به کمک سازه­هایی که اثر تخریبی جریان را بهبود می­بخشند پرداخته­اند. در این مطالعه به بررسی آبشستگی آب زلال در دو تکیه­گاه عمودی با عرض­های مختلف پرداخته شده است. دیواره­ی بالادست تکیه­گاه با المان­هایی برای کاهش گردابه­های نعل اسبی محافظت شده است. اندازه­های مختلف المان­ها با ضخامت و پیش­آمدگی برابر با L025/0، L05/0، L1/0، L2/0، L3/0 (L برابر با طول تکیه­گاه) و در ارتفاع­های مختلف کارگذاری بر دو تکیه­گاه با طول برابر و عرض یکی دو برابر دیگری مورد بررسی قرار گرفته­اند. ارتفاع بهینه اعمال زبری، برابر با L6/0 زیر سطح رسوب به دست آمد. با بزرگتر شدن ابعاد المان­ها تا ضخامت و پیش­آمدگی L2/0، آبشستگی اطراف تکیه­گاه کم می­شود و پس از آن با بزرگتر شدن المان­ها آبشستگی افزایش پیدا می­کند. کارگذاری المان­های با ضخامت و پیش آمدگی L2/0 در عمق L6/0 زیر رسوب بر تکیه­گاه با عرض کمتر، کاهش آبشستگی به میزان 4/30 درصد و بر تکیه­گاه با عرض بیشتر کاهش آبشستگی به میزان 8/32 درصد را نتیجه داد.

کلیدواژه‌ها

موضوعات

عنوان مقاله [English]

Determination of Optimum Depth and Dimensions of Roughening Elements on Bridge Abutment as Scour Countermeasures

نویسندگان [English]

  • Neda Jafari 1
  • Seyed Mohammad Ali Zomorodian 2
  • masiih zolghadr 3
1 Msc Student, Agriculture engineering-Hydraulic structures, Shiraz University, Shiraz, Iran
2 Facility, Agriculture Engineering- Hydraulic structures, Shiraz University, Shiraz, Iran
3 Assistant professor, water Eng. Dept. jahrom University, Jahrom, Iran
چکیده [English]

In the recent years, the failure of many bridges has reported due to local scour around abutment. Many studies have focused on reducing the scour with the help of structures reducing the destructive effects of flow. In this study, the scouring effect on two vertical wall abutments with different widths was investigated using clean water. Where the upstream face of the latter is protected with roughening elements as devices to intercept the down flow responsible for the formation of the principal vortex. Different sizes of the elements with thicknesses and protrusions equal to 0.025L, 0.05L, 0.1L, 0.2L and 0.3L (L is the length of the abutment) placed at different elevations on abutments were investigated. The optimum elevation of roughening elements obtained at 0.6L below the bed level. As the thickness and protrusion dimensions of the elements increases to 0.2L, scour depth around the abutment decreases, and after that increases if the element size become larger. In conclusion, the roughening elements with thickness and protrusion equal to 0.2L and placement of 0.6L below the sediment bed reduced the scour depth 30.4 and 32.8% at the small and large abutments, respectively.

کلیدواژه‌ها [English]

  • Abutment Scour
  • Roughening Elements
  • Optimum Application Depth of Roughening Elements

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تحقیقات آب و خاک ایران
دوره 50، شماره 8
دی 1398
صفحه 2051-2061

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