بررسی آزمایشگاهی اثر مساحت سطح شکاف در بدنه‌ی پایه روی کاهش آبشستگی موضعی پایه پل

نوع مقاله: مقاله پژوهشی

چکیده

      ساخت پایه­های پل در داخل بستر رودخانه­ها غالبا تغییراتی در شکل و مسیر رودخانه­ها ایجاد می­کنند. این تغییرات عکس­العمل­های طبیعی رودخانه را در پی دارد که یکی از آن­ها آبشستگی موضعی در اطراف پایه­ی پل­هاست و می­تواند سالانه خساراتی را به وجود می‌آورد. ازاین‌رو تحقیقات زیادی روی روش‌های کنترل و کاهش آبشستگی انجام‌گرفته است. یکی از روش‌های ارائه‌شده توسط محققان استفاده از شکاف در پایه پل‌هاست. در تحقیق حاضر اثر مساحت سطح شکاف در بدنه­ی پایه روی آبشستگی موضعی اطراف پایه با مقطع مستطیلی به‌صورت آزمایشگاهی مورد بررسی قرارگرفته است. برای این منظور از پایه­های دارای شکاف با مقطع مربعی و به ابعاد متفاوت استفاده گردید. شکاف­ها در سه تراز قرارگیری (نزدیک سطح آب، هم‌تراز بستر و زیر بستر) و در چهار عدد فرود مورد آزمایش قرار گرفت. نتایج نشان داد عمق آبشستگی حداکثر و حجم چاله­ی آبشستگی با تراز قرارگیری شکاف نسبت به بستر و عدد فرود جریان، رابطه­ی مستقیم و با مساحت سطح شکاف، رابطه عکس دارد. بهترین عملکرد شکاف مربوط به شکاف با ابعاد بیشتر و در تراز زیر بستر و در شرایط  کمترین عدد فرود بوده که به میزان ۴/۵۵ درصد عمق آبشستگی را کاهش می دهد.

کلیدواژه‌ها


عنوان مقاله [English]

Experimental Investigation of the Effect of Slot Pier Opening Area on Local Scouring of Bridge Pier

چکیده [English]

   The construction of bridges within the river beds often makes changes to the shape and direction of the rivers. These changes take the natural actions of the river, that one of them is the local scouring around the bridges' piers and can cause annually damage. Therefore, many researches have been carried out to control and reduce the scouring. One of the methods presented by researchers is using slot at piers.  In present study, the effect of Pier Opening Area on local scouring around the pier with rectangular section is experimentally investigated. For this purpose, piers with square shape slots and different dimensions were used. The piers were tested at three levels (near the water level, on the bed and under the bed) and four Froude numbers.  The result showed that the maximum scouring depth and the volume of hole scour had a direct relationship with slot level relative to bed and Froude number and an inverse relationship with Pier Opening Area. The best performance belonged to the slot with greater dimensions which was located under the bed level in the minimum Froude number condition that reduced the depth of scouring about 55.4 percent.  

کلیدواژه‌ها [English]

  • Scouring
  • Pier Bridge
  • Slot
  • Pier Opening Area
  • Experimental study
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