بررسی تأثیر تابع هدایت هیدرولیکی در تحلیل نشت غیر محصور (مطالعه موردی سد خاکی حسنلو)

نوع مقاله : مقاله پژوهشی

نویسندگان

استادیار گروه مهندسی آب، دانشکده کشاورزی، دانشگاه ارومیه، ارومیه، ایران

چکیده

در این تحقیق اهمیت به­کارگیری توابع نفوذپذیری در تحلیل نشت دائم و غیر دائم (انتقالی) غیر محصور در محیط­های همگن و غیر همگن بررسی شد. برای این منظور حالات مختلف جریان در محیط­های همگن و غیر همگن با لحاظ خصوصیات هیدرولیکی مصالح مستخرج از بانک اطلاعاتی خاک­های غیر اشباع (UNSODA) و به کمک یک مدل کامپیوتری مبتنی بر روش اجزای محدود مطالعه شد. برای اعتبار­سنجی نتایج این تحلیل، از داده‌های ابزار دقیق ثبت شده­ی سد حسنلو طی دوره یکساله استفاده گردید. نتایج بررسی­ها نشان داد که در محیط غیر همگن و سدهای ناحیه­بندی شده، خصوصیات هیدرولیکی مصالح پایین دست نسبت به مصالح بالادست بر موقعیت سطح نشت مؤثرتر است. هم­چنین طبق یافته‌های تحقیق، موقعیت سطح نشت در شرایط به­کارگیری هدایت هیدرولیکی ثابت نسبت به هدایت هیدرولیکی متغیر در شرایط بالا آمدن سطح آب در مخزن رشد آهسته­تری داشته و در عین حال در شرایط پایین افتادن سطح آب در مخزن، سرعت زهکشی مصالح بیش­تر می­باشد. مقایسه داده­های واقعی ثبت شده با نتایج مدل نشان می‌دهد که جهت حصول نتایج واقع بینانه لازم است خصوصیات هیدرولیکی مصالح به­صورت تابع هدایت هیدرولیکی تعریف گردد یا اینکه حداقل برای مصالح پایین دست این شرایط رعایت شود.  

کلیدواژه‌ها


عنوان مقاله [English]

Investigation on the Effects of Hydraulic Conductivity Function in Unconfined Seepage Analysis (Case study: Hassanlu Earth Dam)

نویسندگان [English]

  • Hojat Ahmadi
  • Vahid Rezaverdinejad
Assistant Professor, Department of Water Engineering , Faculty of Agriculture, Urmia University., Urmia., Iran
چکیده [English]

In this research the emphasis of the application of hydraulic conductivity function in seepage analysis through in homogenous and nonhomogeneous medium was investigated. For this aim, different forms of flow in mentioned mediums were analyzed via a finite element numeric model based on hydraulic properties were selected from unsaturated soils database (UNSODA). In order to validate the results annual recorded data in Hassanlu earth dam was used.  The results showed, in nonhomogeneous medium as well as zoned earth dams, the role of downstream material is more significant. Furthermore, the phreatic line in the state of employing constant conductivity in instead in conductivity function rises rapidly in the conditions of rising water lever at the boundaries while in drawdown it drain faster. Comparison between filed data and model results also showed to get realistic results employing of hydraulic conductivity in the form function is essential at least for downstream materials.
 

کلیدواژه‌ها [English]

  • Hydraulic Conductivity Function
  • Material
  • Earth Dam
  • Seepage
Arya,L.M and Paris,J.F. 1981. A physicoempirical model to predict the soil moisture characteristic for particle-size distribution and bulk density data. Soil Soil Science Society of America Journal. 45: 1023-1030.
Balaam,N. 2005. Finite element seepage analysis: FESEEP. Center for Geotechnical Research University of Sydney.
Bardet,J.P., Tobita,T. 2002 A practical method for solving free-surface seepage problems. Computers and Geotechnics. 29: 451-475.
Fredlund,D.G and Rahardjo, H. 1993. Soil mechanic for unsaturated soil. John wiley & sons Inc. 
Fredlund,D.G and Xing,A. 1994. Equations for the soil-water characteristic curve. Canadian Getechnical Journal. 31 (4): 521-532.
Ghanbarian-Alavijeh,B., Liaghat.A., Huang,G.H and Van Genuchten,M.Th. 2010. Estimation of the van genuchten soil water retention properties from soil textural data. Pedosphere, 20 (4): 456-465.
Green,R.F and Corey,J.C. 1971. Calculation of hydraulic conductivity: a further evaluation of some predictive methods. Soil Sci. Soc. Am. Proceeding. 35: 3-8.
Gupta,S.C and Larson,W.E. 1979. Estimating soil water retention characteristics from particle size distribution, organic matter percent and bulk density. Water resource research. 15: 1633-1635.
Ji,Ch.N., Wang,Y.Z and Shi,Y. 2005. Application of modified EP method in steady seepage analysis. Computers and Geotechnics. 32 (1): 27-35.
Krahn,J. 2004. Seepage modeling with Seep/w: an engineering methodology. Geo-Slope International Ltd. Canada.
Leij, F.J., Alves, W.J., Van Genuchten, M.Th., and Williams, J.R. 1996. Unsaturated soil hydraulic database, UNSODA 1.0 User’s manual. EPA Report 600/R96/095. USEPA, Ada
Moriasi,D.N., Arnold,J.G., Van Liew,M.W., Harmel, R.D and Veith,T.L. 2007. Model evaluation guidelines for systematic quantification of accuracy in watershed simulation. American society of agriculture and biological engineers. 50 (3): 885-900.
Munoz,J.J., Delaure,E and De Gennaro,V. 2008. Experimental determination of unsaturated hydraulic conductivity in compacted silt. Unsaturated soils: Advances and in geo-engineering. Taylor and Francis group. London.
Sang Il,H., and Sang Il,Ch. 2006. Use of a logarithmic distribution model for estimation soil water retention curves from particle-size distribution data. Journal of Hydrology. 323: 325-334.
Saxton,K.E., Rawls,W.J., Romberger,J.S and papendik, R.I. 1986. Estimating generalized soil-water characteristics from texture. Soil Sci. Soc. Am. Journal. 50 (4): 1031-1036.
Srivastava,A., Sivakumar Babu,G.L and Halder,S. 2010. Influence of spatial variability of permeability on steady state seepage and slope stability analysis. Engineering Geology. 110 (3-4): 93-101.
Smettem,K.R.J and Gregory,P.J. 1996. The relation between soil water retention and particle-size distribution parameters for some predominantly sandy western Australian soils. Aust. J. Soil Research. 34 (5): 695-708.
Timlin, D.J. Pachepsky, Ya.A, Acook, B. and whisler,F. 1996. Indeirect estimation of soil hydraulic properties to predict soybean yield using GLYSIM. Agricultural system. 52 (2/3). pp. 331-353.
Van Genuchten,M.Th. 1980. A closed form equation for predicting hydraulic conductivity of unsaturated soils. Soil science society of America journal. 44: 892-898.
Van Genuchneten,F.J., Leij,F.J and Yates,S.R. 1991. The RETC code for quantifying the hydraulic functions of unsaturated soils. U.S. Salinity: Laboratory. Agricultural research service. California. USA.
Xu,Y.Q., Unami,K and Kawachi,T. 2003. Optimal hydraulic design of earth dam cross section using saturated-unsaturated seepage flow model. Advance in Water Resource. 26 (1): 1-7.
Zhang,Y.L., Chen,R and Li,J.H. 2011. Evaluation the accuracy of unsaturated hydraulic conductivity determined by instantaneous profile method. Unsaturated Soils: Theory and Practice. Proceeding. Kasetsart University, Thailand.