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

مراجع

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علوم و مهندسی آبیاری
دوره 42، شماره 1
فروردین 1398
صفحه 99-114

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سابقه مقاله

  • تاریخ دریافت: 28 بهمن 1395
  • تاریخ بازنگری: 05 تیر 1396
  • تاریخ پذیرش: 11 تیر 1396
  • تاریخ انتشار: 01 فروردین 1398

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