مطالعه آزمایشگاهی جریان غیر دارسی درون مصالح متخلخل دانه ای

نوع مقاله : مقاله پژوهشی

نویسندگان

1 کارشناس ارشد ژئوتکنیک دانشگاه یاسوج

2 استادیار دانشکدة کشاورزی گروه علوم خاک دانشگاه یاسوج

3 استادیار دانشکدة مهندسی گروه عمران دانشگاه یاسوج

چکیده

استفاده از مصالح درشت‏دانة سنگ‌ریزه‏ای در سازه‏های آبی، به دلیل خصوصیات ویژة آن‌ها، روز‏به‏روز رو‏ به افزایش است، طوری که امروزه از این مصالح برای ساخت فیلتراسیون و حوضچه‏های آرامش و سدهای پاره‏سنگی استفاده می‏شود. به دلیل اهمیت جریان درون مصالح سنگ‌ریز، مطالعة خصوصیات این نوع جریان اهمیت خاصی دارد. به منظور بررسی رفتار جریان درون مصالح دانه‏ای دستگاه پرمئامتری با بارثابتی طراحی و ساخته شد. آزمایش‏هایی روی سه نمونه از  ذرات سنگ‌ریزه‏ای با قطرهای متوسط 69/8، 08/13، و 617/16 میلی‌متر انجام و خصوصیات آن‏ها ارزیابی شد. نتایج آزمایشگاهی نشان داد رابطة بین سرعت و گرادیان هیدرولیکی غیر خطی است و از قانون دارسی تبعیت نمی‏کند. مشاهده می‌شود، با افزایش عدد رینولدز، فاکتور اصطکاکی کاهش می‌یابد و با افزایش گرادیان هیدرولیکی عدد رینولدز نیز افزایش پیدا می‏کند. این وضعیت حاکی از متلاطم‌بودن جریان در گرادیان‏های بالاست. همچنین ارزیابی نتایج این پژوهش به وسیلة شاخص آماری و مقایسة آن با روابط Kadlec and Knight (1996) و Ergun (1952) نشان داد رابطة کادلیک و نایت خطای کمتری نسبت به رابطة ارگان دارد.

کلیدواژه‌ها

موضوعات

عنوان مقاله [English]

An Experimental Investigation of Non-Darcy Flow in Granular Porous Materials

نویسندگان [English]

  • Mohammad Bagher Salahi 1
  • Mohammad Sedghi-Asl 2
  • Mansoor Parvizi 3
1 MA student in Geotechnics, Yasouj University
2 Assistant professor, Faculty of Agriculture, Department of Soil Science, Yasouj University
3 Assistant professor, Faculty of Engineering, Department of Civil Engineering, Yasouj University
چکیده [English]

Use of large grained gravel is increasing in hydraulic structures due to their specific features as regards filtration, canal covers, stilling basins, rockfill dams, etc. Flow behavior in high porosity media and as well in rockfill dams is very complex due to the existence of large pore size and consequently turbulence in the flow. Given the importance of flow within the rockfill materials, an investigation of the characteristics of this type of flow is indispensable. Considering the widespread use of large grained materials in civil projects, scrutinizing the flow properties in these materials and obtaining their hydraulic parameters is important as for non-Darcy flow studies. In order to study the flow behavior in grained materials, a constant-head permeameter was designed built. Experiments were carried out on three types of gravel grains with average diameters of 8.69, 13.08, and 16.62 mm. During the course of experiments, the outlet discharge, upstream and downstream heads as well as a measurement of the pressure drop (difference between water levels in upstream and downstream tanks), were recorded and their characteristics studied. The laboratory results indicate that the relationship between flow velocity and gradient is non-linear, following non-Darcy’s law. The evaluation of results using goodness of fit criteria and their comparison with Kadlec and Knight (1996) and as well Ergun (1952) relations show that the Kadlec and Knight (1996) relation is of a higher reliability than latter. Variation of Reynolds number versus friction factor shows that the more the diameter of materials, the lower the abrasion factor and the higher the Reynolds number. The friction factor in higher Reynolds numbers decreases so that it is independent of the grain diameter and of Reynolds' number. The low pressure equations and relations obtained in this study can be used for calculation of water surface profile through dams and rock drains.

کلیدواژه‌ها [English]

  • constant head
  • flow characteristics
  • prmeameter device
  • large-grained materials

مراجع

Abelin, H., Birgersson, L., Moreno, L., Widen, H., Agren, Th., And Neretnieks, I. (1991) A Large-Scale Flow and Tracer Experiment in Granite: 2. Results and Interpretation. Water Resour. Res. 27, 3110-3135.
Ahmed, N. and Sunada, D. K. (l969). Nonlinear Flow in Porous Media. Journal of the Hydraulics Division, Am. Soc. Civil Engrs., Vol. 95, NO. HY 6. 1847.
Ergun S. (1952). Fluid flow through packed columns. Chemical Engineering Progress, 48(2), 89-94.
Forchheimer, P. (1901). Wasserbewegung durch boden, Zeit. Ver. Deutsch. Ing. 45, 1781–1788.
Hall, K. R., Smith, G. M., and Turcket, D. J. (1994). Development of a non-linear porous media flow relationship for oscillatory unsteady flow. J. of Coastal Research, 10(1), 158-169.
Hansen, D. (1992). The behavior of flowthrough rockfill dams. Ph. D. thesis, Department of Civil Engineering, University of Ottawa, Ottawa, Ontario, p. 103 - 111.
Hosseini, S. M. and Joy, D. M. (2006). Calibration of Hydraulic Parameters for Flows Through Rockfill Structures. Dam Engineering, 17(2), 85-111.
Kadlec, H. R. and Knight, L. R. (1996). Treatment Wetlands. Lewis Publishers.
Kovács, G. (1981). Seepage Hydraulics, Development in Water Sciences. Elsevier, NY.
Leps, T. M. (1973). "Flow through rockfill-embankment dam engineering, Casagrande volume", edited by Hirschfield, R. C. and Paulo’s, S.J., John Wiley and Sonse, New York, PP.87-107.
Li, B., Garga, V. K., and Davies, M. H. (1998). ‘‘Relationships for non-Darcy flow in rockfill.’’ J. Hydraul. Eng., 124)2(, 206–212.
Martins, R. (1990). “Turbulent seepage flow through rockfill structures”. Water Power & Dam Construction,. March 1990, p. 41-45.
Mc Corquodale, J. A., Hannoura, A., and Nasser, M. S. (1978). Hydraulic conductivity of rockfill. Journal of Hydraulic Research, 16(2), 123 - 137.
Salehi, R., Rahimi, H., and Hope, B. C. (2005). An Empirical study of turbulent flow through confined coarse porous media. Iranian Journal of Agricultural Sciences. 36( 2), 263-271. (In Persian)
Samani, J. M. V., Samani, H. M. V., and Shaiannejad, M. (2004). Reservoir routing with outflow through rockfill dams. J. Hydraulic. Res. 42(4), 435–439.
Sedghi-Asl, M. and Rahimi, H. (2011). adoption of Manning equation for 1-D non-Darcy flow Problems. Journal of Hydraulic Research 49(6), 814-817.
Sedghi-Asl, M., Rahimi, H., and Salehi, R. (2014). Non-Darcy flow of water through a packed column test. Transport in Porous Media 101(2), 215-227.
Stephenson, D. (1969). Rockfill in Hydraulic Engineering, Elsevier scientific, Amsterdam.
Ward, J. C. (1964). Turbulent flow in porous media, J. Hydraul. Div. Am. Soc. Civ.90(HYD5).
Wilkins, J. K. (1956). Flow of water through rockfill and its application to the design of dams. Proceedings of the 2nd Australia-New Zealand Conference on Soil Mechanics and Foundation Engineering, Canterbury University College, Christchurch, New Zealand.
Zingg, T. (1935). Beitrag zur Schotteranalyse. Schweizerische Mineralogische und Petrologische Mitteilungen 15, 39–140.

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