بررسی آزمایشگاهی اثرات حفره برداشت شن و ماسه رودخانه‌ای بر روی پایه‌های پل مجاور

نوع مقاله: مقاله پژوهشی

نویسندگان

1 دانشیار گروه مهندسی عمران، دانشکده فنی و مهندسی، دانشگاه مراغه، مراغه، ایران.

2 استادیار گروه مهندسی عمران، دانشکده فنی و مهندسی، دانشگاه مراغه، مراغه، ایران.

3 فارغ‌التحصیل کارشناسی ارشد سازه‌های هیدرولیکی، گروه مهندسی عمران، دانشگاه مراغه، مراغه، ایران

4 دانشجوی دوره دکترای، عمران آب و سازه های هیدرولیکی، دانشگاه زنجان، زنجان، ایران.

چکیده

سهولت برداشت مصالح باکیفیت از رودخانه­ها و هزینه­های پایین آن، استفاده از این منابع را بیشتر نموده است. در این تحقیق به بررسی آزمایشگاهی تأثیر انتقال و توسعه گودال­های ایجاد شده ناشی از برداشت مصالح رودخانه­ای بر روی پایه­های پل مجاور احداثی در مسیر جریان آب پرداخته و از پایه­های پل دایره­ای شکل و مستطیلی نوک­تیز استفاده گردید. نتایج آزمایش­ها نشان داد که حفره برداشت شده برای رسیدن به تعادل رسوب ورودی و خروجی تا پایه­های پل مستقر در مجاورت گودال ادامه یافته و باعث فرسایش در اطراف هر دو پایه پل در بالادست و پایین­دست محل خود می­گردد. همچنین تأثیر حفره برداشت بر روی آبشستگی اطراف پایه پل بالا­دست بیشتر از پایه پل پایین­دست می­باشد. با توجه به شکل­ آئرودینامیکی دماغه پایه پل مستطیلی نوک­تیز مقدار حداکثر عمق آبشستگی در اطراف پایه پل بالادست و پایین­دست به ترتیب 50/24 و 55/31 درصد نسبت به پایه پل دایره­ای شکل کاهش می­یابد. در نهایت با  ارائه روابط تجربی برای حداکثر طول و عمق آبشستگی حفره برداشت، عوامل هندسی و مؤثر بر روی آبشستگی پایه­ها و درصد خطای نسبی و RMSE روابط بدست آمده ارزیابی و نمودارهای مربوط به آن­ها جهت بررسی استخراج گردید. مشاهده گردید که در هر دو دانه­بندی با کاهش عمق گودال­ها و همچنین با کاهش Fr، نسبتبی­بعد ­H/y (نسبت ارتفاع گودال به عمق جریان) کاهش و نسبت­های بی­بعد L/y، B/y­ (نسبت طول و عرض گودال به عمق جریان) افزایش می­یابد. در نهایت پارامترهای تأثیرگذار در حداکثر طول و عمق آبشستگی گودال برای هر دو پایه پل دایره­ای و مستطیلی نوک­تی­شناسایی و معرفی گردید.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

The Experimental Study of the Effects of River Mining Holes on the Bridge Piers

نویسندگان [English]

  • Rasoul Daneshfaraz 1
  • Jafar Chabokpour 2
  • Mmehdi Desineh 3
  • amir Ghaderi 4
1 Associate Professor Dr., Department of Civil Engineering, Faculty of Engineering, University of Maragheh, Maragheh, Iran.
2 Assistant Professor Dr. ,Department of Civil Engineering, Faculty of Engineering, University of Maragheh, Maragheh, Iran.
3 Graduated study of the hydraulic structures, Civil engineering department, Faculty of engineering, University of Maragheh, Maragheh, Iran
4 Department of Civil Engineering, Faculty of Engineering, University of Zanjan, Zanjan, 45371 - 38791, Iran
چکیده [English]

The Easiness of mining from the rivers and its low cost have increased use of these resources. In the present study, the effects of pit migration and development on the bridge inline piers were investigated experimentally. The circular and sharp rectangular shapes of the piers have been employed in this study. The results showed that the pit holes are developed to the downstream and upstream bridge piers in order to achieve sediment balance, which causes piers scouring at downstream and upstream. Also, the development of the holes towards upstream pier is more than the downstream pier. Regarding to aero-dynamical shape of the rectangular sharp nose bridge, the magnitude of the scouring hole at the up and downstream is reduced 24.5 and 31.55% respectively as compared to circular piers. Finally, the empirical relationships related to the maximum length and depth of scouring were derived. By using these relationships, the geometric and effective statistical parameters on the pier scouring, as well as the relative error percentage and RMSE of the obtained functions were evaluated and the depended graphs were depicted. It was found for both sediment dimensions, by reduction of the hole depth and Fr number, the dimensionless parameter of the H/y(the pit holes depth to flow depth) is decreased and the L/y and B/y (the pit holes length and width to flow depth) parameters are increased. Finally, the parameters affecting the maximum length and depth of the pit scouring were identified and introduced for both sharp piers.

کلیدواژه‌ها [English]

  • : river sand and gravel mining
  • pit hole
  • scouring length and depth
  • bridge piers
  • empirical relationships

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