بررسی آزمایشگاهی فرآیند ته‌نشینی رسوبات معلق در مخزن سد کرخه

نوع مقاله : مقاله پژوهشی

نویسندگان

1 دانشگاه فردوسی مشهد، دانشکده علوم مهندسی آب، خراسان رضوی، ایران

2 مرکز تحقیقات منابع آب دانشگاه شهرکرد، چهارمحال و بختیاری، ایران

3 دانشگاه شهرکرد، دانشکده کشاورزی، چهارمحال و بختیاری، ایران

4 سازمان آب و برق خوزستان، خوزستان، ایران

چکیده

یکی از پیش نیازهای اصلی مدیریت رسوب در مخازن سدها، شناخت ویژگی و پارامترهای موثر ته نشینی رسوبات در مخزن سد می‌باشد. در این تحقیق به بررسی فرآیند ته نشینی رسوبات معلق سد کرخه پرداخته شده است. به همین منظور پس از نمونه برداری از رسوبات مخزن سد کرخه، آزمایش‌های ته نشینی در فلوم دایرهای آزمایشگاه هیدرولیک دانشگاه شهرکرد با هدف تعیین شرایط هیدرولیکی مناسب به منظور رسوب شویی مخزن این سد انجام گرفت. آزمایش‌ها در غلظت‌های اولیه 5 و 10 و 20 گرم برلیتر انجام شد و تنش برشی آستانه و ته نشینی کامل، سرعت غیر رسوب گذار و نرخ ته نشینی رسوبات مورد بررسی قرار گرفت. بر این اساس تنش برشی آستانه ته نشینی معادل 1/ 0  نیوتن بر متر مربع به دست آمد. همچنین مشخص شد در حالتی که سرعت جریان بیشتر از 61 / 0 متر بر ثانیه باشد، رسوبات به صورت معلق باقی مانده و ته نشین نمی‌شوند که در این شرایط، تن شبرشی معادل 55 / 2 نیوتن بر متر مربع و عدد فرود جریان برابر 43 / 0 به دست آمد. همچنین نتایج نشان داد در غلظت‌های رسوب بیشتر، افزایش تنش برشی جریان در کاهش نرخ ته نشینی تاثیر بیشتری دارد.

کلیدواژه‌ها

موضوعات

عنوان مقاله [English]

Experimental Study on suspended sediment deposition process in Karkheh dam reservoir

نویسندگان [English]

  • M. Khastar- Boroujeni 1
  • H. Samadi-Boroujeni 2
  • R. Fattahi-Nafchi 3
  • M. Ghasemi 2
  • ََA. Naghshbandi 4
  • M. Heidari 4
1 Water Engineering Department, Ferdowsi University of Mashhad, Mashhad, Iran.
2 Water Engineering Department, Water Resources Research Center, Shahrekord University, Shahrekord, Iran.
3 Water Engineering Department, Water Resources Research Center, Shahrekord University, Shahrekord, Iran.
4 Water Engineering Department, Water Resources Research Center, Shahrekord University, Shahrekord, Iran
چکیده [English]

One of the most essential works for sediment management in dam reservoirs is to identify the characteristics and effective parameters of deposition of sediments in the dam reservoir. In this research, the sedimentation process of fine sediments deposited into Karkheh dam reservoir was investigated in order to determine the required hydraulic conditions for desilting of the reservoir. Experiments were carried out in an annular flume located in Hydraulic Laboratory of Shahrekord University and sediment samples were taken from reservoir of Karkheh dam. Experiments were done at initial concentrations of 5, 10 and 20 g/l, and various shear stresses to determine the threshold shear stress for partial deposition and full deposition of suspended sediments. The obtained results showed that the shear stress of the initiation of sediment deposition was 0.1 N/m2. It was also found that when the flow velocity to be exceed up to 0.61 m/s, the sediments would be completely remained in term of suspension. Under these conditions, the shear stress and Froude number were obtained as 2.55 N/m2 and 0.43, respectively. Also, the results showed that in higher sediment concentrations, increasing of shear stress is more effective in the sediment deposition rate.

کلیدواژه‌ها [English]

  • Critical shear stress
  • sediment deposition rate
  • Sedimentation
  • Karkheh Dam

مراجع

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نشریه مهندسی عمران امیرکبیر
دوره 51، شماره 2
خرداد و تیر 1398
صفحه 327-340

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