بررسی آزمایشگاهی جریان مستغرق سرریز گابیونی لبه پهن با شیب بالادست و پایین‌دست

نوع مقاله: مقاله پژوهشی

نویسندگان

1 دانش آموخته کارشناسی ارشد سازه های آبی، دانشکده مهندسی علوم آب، دانشگاه شهید چمران اهواز.

2 استاد گروه سازه‌های آبی، دانشکده مهندسی علوم آب، دانشگاه شهید چمران اهواز

3 دانش‌آموخته دکتری سازه‌های آبی، دانشکده مهندسی علوم آب، دانشگاه شهید چمران اهواز.

چکیده

برخلاف سرریزهای معمولی نفوذ ناپذیر، مواد فیزیکی و شیمیایی از درون سرریزهای گابیونی به پایین‌دست عبور می‌کنند. بنابراین سرریزهای گابیونی
 سازه‌هایی با حداقل اثرات منفی بر محیط ‌زیست بوده و به سازه‌های دوست­دار محیط ‌زیست معروف هستند. در این تحقیق تأثیر اندازه مصالح، شیب بالادست و شیب پایین‌دست بر فاکتور کاهش دبی جریان در سرریزهای گابیونی با شرایط جریان مستغرق بررسی شد. در ابتدا پس از شناسایی پارامترهای مؤثر، رابطه عمومی بدون بعد توسعه داده شده است. برایانجام آزمایش‌ها 16 مدل مختلف سرریز گابیونی
 در یک فلوم آزمایشگاهی افقی به طول، عرض و ارتفاع به­تر تیب برابر  15، 3/0 و 5/0 متر مورد بررسی قرار گرفتآزمایش‌ها برای دامنه
 وسیعی از دبی،عمق بالادست،عمق پایین‌دست، اندازه مصالح، شیب بالادست و شیبپایین ‌دست انجام شدنتایج نشان داد در تمامی مدل‌های گابیونی
 با افزایش نسبت عمق پایین‌دست به عمق بالادست سرریز (Y2/Y1) فاکتور کاهش دبی، کاهش می‌یابد. به ازایمقدار ثابت نسبت (Y2/Y1)، افزایش شیب بالادست و یا پایین‌دست سرریز لبه پهن گابیونی، فاکتور کاهش دبی رو به افزایش می‌گذارد. هم­چنین اندازه مصالح تأثیر معنی‌داری بر فاکتور کاهش دبی ندارد. در این تحقیق با استفاده از رگرسیون غیر خطی رابطه‌ای با ضریب تعیین بین 12/0 تا 91/0 جهت محاسبه میزان فاکتور کاهش دبی ارایه ‌شدهاست.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Experimental Investigation of Submerged Flow over Porous Embankment Weirs with Up and Downstream Slopes

نویسندگان [English]

  • Mehrzad Moradi 1
  • Manochehr Fathi-Moghadam 2
  • Leila Davoudi 3
1 M.Sc Graduate, Department of Water Science Engineering, Shahid Chamran University of Ahvaz.
2 Professor, Department of Water Science Engineering, Shahid Chamran University of Ahvaz
3 Ph.D. Graduate, Department of Water Science Engineering, Shahid Chamran University of Ahvaz .
چکیده [English]

Embankment weirs are finite crested weirs with various side slopes that can be used for different purposes such as flow measurement and diversion, water level management, aeration or water purification, etc. The hydraulic performance and the characteristics of flow over solid weirs with finite crest length in free and submerged flow conditions have been of interest to many studies (Azimi and David. 2013). Unlike the impermeable weirs, porous weirs contribute to the water purification in the rivers and channels downstream of the structures. Hence, they are structures with positive impact on water treatment.
Sargison and Percy (2009) studied the performance of BC weirs with side slopes varying between vertical positions to 1V:2H. Results indicated that by decreasing the slope of upstream face, the discharge coefficient increases and the height of the upstream water surface reduces. Although the characteristics of flow over porous weirs have been studied until now, there are still remaining facts to discover about performance of these kinds of structures in practice. Hence, this study has benefited from extensive experimental data obtained by laboratory tests to develop formulas to estimate hydraulic parameters for discharge reduction factor in the submerged flow conditions. This study investigates the hydraulic performance of flow over the porous embankment (PE) weirs for both free and submerged flow conditions. To do this, the hydraulic behavior of flow over 16 different PE weir models was examined in a rectangular flume. Results showed that the effect of the upstream slope of weirs is negligible on the modular limit index while the downstream slopes of weirs did not affect the free flow parameters. Also, both up- and downstream side slopes have no significant effect on the characteristics of the submerged flow.

کلیدواژه‌ها [English]

  • Porous embankment weir
  • submerged flow
  • Modular limit
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