بررسی آزمایشگاهی تأثیر آرایش قرارگیری صفحات مستغرق تخت بر آبشستگی در اطراف ‌پایه‌ها و تکیه‌گاه پل

نوع مقاله : مقاله پژوهشی

نویسندگان

1 دانش آموخته کارشناسی ارشد سازه‌های آبی، بخش علوم و مهندسی آب، دانشگاه شهید باهنر کرمان، ایران

2 گروه مهندسی آب دانشکده کشاورزی دانشگاه باهنر کرمان

3 مهندسی آب، کشاورزی، دانشگاه شهید باهنر کرمان، کرمان، ایران

چکیده

پایه‌­ها و تکیه­‌گاه‌­های جانبی پل در عرض رودخانه باعث تغییر الگوی جریان آب و در نتیجه موجب آبشستگی موضعی در اطراف این سازه‌­ها می­‌شوند. روش‌­های مختلفی برای کاهش آبشستگی موضعی در اطراف پایه‌­ها و تکیه­‌گاه­‌های جانبی پل پیشنهاد شده که یکی از آن­ها استفاده از صفحات مستغرق است. این صفحات با تغییر در رژیم حرکت بار بستر، این امکان را فراهم می‌­سازند تا محل رسوب‌­گذاری و فرسایش قابل ‌کنترل باشد. عملکرد صفحات مستغرق در کاهش آبشستگی پایه و تکیه‌­گاه پل و حرکت رسوب از اطراف صفحات که موجب ایجاد جریان روبه پایین در جلوی آن­ها  می‌­شود، تحت تأثیر نحوه­ی قرارگیری صفحات مستغرق می­‌باشد. در این پژوهش، تأثیر آرایش­­‌های مختلف قرارگیری (تک‌ردیفه موازی، دو ردیفه موازی و دو ردیفه زیگزاکی) صفحات مستغرق تخت با نسبت طول به ارتفاع  در زاویه قرارگیری 20 درجه نسبت به جهت جریان، بر کاهش آبشستگی گروه پایه و تکیه‌­گاه پل در حضور اجسام شناور مستطیل شکل به ‌صورت آزمایشگاهی مورد بررسی قرار گرفته است. تمامی آزمایش­‌ها در شرایط جریان یکنواخت با آب زلال و رسوبات غیر چسبنده­ای با قطر متوسط mm 0/91=  d50انجام‌ شده است. نتایج حاکی از آن بود که آرایش دو ردیفه سه‌تایی به صورت زیگزاکی بیشترین تأثیر را در کاهش آبشستگی و حفاظت پایه­‌ها و تکیه­‌گاه داشته است. در این حالت فاصله صفحات از تکیه­‌گاه و فاصله ردیف‌­ها با فاصله نسبی0/5 و 1 می‌­باشد. (فاصله صفحات از تکیه‌­گاه به اندازه La و فاصله ردیف‌­ها از هم 2La بوده ) که موجب کاهش 81 درصدی عمق آبشستگی گردیده ­است.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Laboratory Investigation of Effect of Flat Submerged Vanes on Scour at Bridge Piers Group and Abutment

نویسندگان [English]

  • Maryam Karimi 1
  • Kourosh Qaderi 2
  • Majid Rahimpour 3
  • Mohammad Mehdi Ahmadi 3
1 MSc Water structure, Department of Water Engineering, Faculty of Agriculture, University of Shahid Bahonar Kerman
2 water engineering department, faculty of agriculture, shahid bahonar university of kermen
3 Water Engineering, Agriculture, Shahid Bahonar University of Kerman, Kerman, Iran
چکیده [English]

Local scour involves the removal of material from around piers and abutments as the flow accelerates around the obstructed flow area. Various methods have been suggested for the control and reduction of local scour around the bridge piers and abutment. Using submerged vanes is one of these methods. Vanes change the regime of bedload movement that led to control places of deposition and erosion. The function of vanes to reduce scour around the bridge piers and sediment movement in the region of vanes due to downflow in front of them are affected by arrays of the vanes. In the present study, different layouts of arrangements (parallel rows, two parallel rows, and two zigzag rows) flat submerged vanes with the ratio of length to height (L/H=3) at an angle of 20 degrees relative to the direction of flow on the protection of local scour around abutment and piers group with rectangular debris were investigated. All experiments conducted in uniform flow with clear water were being done. The results showed that the zigzag arrangement of the two-three rows had the greatest effect on the protection of local scour around the abutment. In this case, the vane distance from the abutment and the row spacing with the relative spacing is 0/5 and 1, respectively, (the distance of the vanes from the abutment was La and the distance of the rows was 2La) that reduced the scour depth by 81%.

کلیدواژه‌ها [English]

  • Local scour
  • Submerged vanes
  • layout of arrangement
  • bridge abutment
  • Protection
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