تعیین ارتفاع فیلتر قایم در سدهای غیرهمگن با هسته‌ی رسی قایم

نوع مقاله : مقالات پژوهشی

نویسندگان

دانشگاه فردوسی مشهد

چکیده

یکی از مشکلات سدهای خاکی در هنگام بهره‌برداری، وقوع پدیده‌ی پایپینگ می‌باشد. این پدیده به خاطر بالا رفتن گرادیان هیدرولیکی موجود از گرادیان هیدرولیکی مجاز می‌باشد. راهکارهای مختلفی برای حل این مشکل پیشنهاد شده است. یکی از این راهکارها استفاده از ترکیب هسته رسی با فیلتر پایین دست هسته رسی می‌باشد. به همین منظور در این تحقیق با استفاده مدل آزمایشگاهی و مدل نرم افزاری PLXIS V8.5 سعی در پیش‌بینی ابعاد بهینه این نوع فیلترها شده است. سه مدل آزمایشگاهی به طول 2/4 متر و ارتفاع یک متر و شیب بدنه 1H : 2V در فلوم آزمایشگاهی تهیه شد. پس انجام آزمایشات و ترسیم خطوط نشت در مدل‌های ازمایشگاهی، با استفاده از مقایسه آماری بین مدل‌های آزمایشگاهی و مدل نرم‌افزاری صحت داده‌های نرم‌افزاری با استفاده از آزمون آماری P-VALUE و RMSE سنجیده شد. در نهایت با استفاده از مدل نرم‌افزاری فیلتر پیشنهادی برای سدهای خاکی با هسته قایم ارایه شد. نتایج نشان داد که ارتفاع فیلتر رابطه مستقیمی با نسبت هدایت هیدرولیکی هسته به پوسته سدهای رسی با هسته‌ی قایم دارد. بدین صورت که با افزایش این نسبت ارتفاع فیلتر پیشنهادی نیز افزایش پیدا می‌کند. در نهایت ارتفاع این فیلتر ارایه شد.

کلیدواژه‌ها


عنوان مقاله [English]

Determine the Height of the Vertical Filter for Inhomogeneous Dams with Vertical Clay Core

نویسندگان [English]

  • Saeed Salehi
  • Kazem Esmaili
Ferdowsi University of Mashad
چکیده [English]

Introduction: Today, always some occurrences threat the earth. One of the most important of this event is seepage from earth dam. It can wash interior body of earth dam that finally might ruins whole the earth dam. For investigating these events in this research some experiments for expressing some alternatives to solve this problem in earth dam with clay core were investigated. In first step has been introduced new design in earth dam that it includes earth dam with clay core.
Materials and Methods: In order to determine the height of the filter after the vertical clay core in non-homogeneous earth dam,3 experimental model with length 2/4 meter and a height of one meter and Body slope 1H: 2V was prepared. This model made in Shahrekord University. In flume that has 0.6 meter with, 6-meter length and 1-meter height. This flume has a drain in downstream which determine the discharge through earth dam. Front of flume made glass for visual inspection and behind flume made by steal sheet that was welded. Also, for embankment model, two types of fine-grained and coarse-grained soils were used that determine the range of hydraulic conductivity of soils was performed with Using aggregation experiments model and Soil Mechanics hydrometer. For embankment model use layer have 0.1meter height and this layer was impacted after an after. Finally, dam was built. The slope of models was elected in reference that had normal range and had economical cases. In the first downstream the dam crest was used fine-grained soil and upstream of the dam crest was used coarse-grained soil finally experiment done. In models 2 and 3 with cutting fine grained soil from the toe of the dam to the dam crest vertical clay core was created. The parameter a /L was introduced. A is thickness of clay core and L is the Length base of the dam although in the second model and the third model was selected. Level of water in pound was performed in 3 water height 80 and 55 and 30 and in 3 level of water determinate pressure with 30 embedded piezometers and this data was used in method model .as well as phreatic line was determinate by using of wells and 30 embedded piezometers in the model. Seven holes were instated in body of earth dam in 3 models for visual inspection of phreatic line. In 3 model of earth dam decline clay core in laboratory for show this effect in discharge and phreatic line use Method model. Then the rates of decline in clay core in the laboratory with modeling in software PLAXIS V8.5 were compared. The rate of high filter after the clay core with safety factor 1.2 (Encounter Line Leak with 20% of the bottom filter) was introduced. Finally use SAS software to compare the result of data in filth and software after that comparing show can use software for continue the experiment with Method Model. With change the permeability in PLXIS V8.5 modeling another state. Permeability, this modeling showed that tackiness and permeability of vertical core soil effect in height of vertical filter in downstream. So, can decline this case with choose non-permeability in core. That show in result of this paper. With the class of soil and permeability and change the tackiness of core can estimate height of filter in downstream.
Results and Discussion: Finally, Analysis and comparison between water Failure in interface of fine-grained and coarse-grained soils, both of Software model and laboratory model have a relatively well fit. To obtain the height of Suggested filter, the software model was used to simulate the experiments and Subtracting the thickness of the fine-grained. By applying safety factor of 1.2, Height was designed to filter and after that the clay core was introduced. Software model results show that by increasing clay core thickness the angle of broken-seepage line is increased. Also, the experimental model can emphasize this matter. Finally, by using vertical clay core against the clay core with slop can improve the application of earth dam and by using his plan can improve and diminish the seepage from the earth dam body that this design process was expressed in this research.

کلیدواژه‌ها [English]

  • Height Filter
  • Model of non-homogeneous earth dam
  • Software PLAXIS V8.5
  • Thickness of the clay core
1- Arulanandan K., Edward B., and Perry M. 1983. Members, Erosion in Relation to Filter Design Criterian in Earth Dams. J. Geotech. Engrg. 1983.109:682-698.
2- Ching S., and Chang M. 1987. Boundary Element Method in Drawdown Seepage Analysis for Earth Dams. J. Comput. Civ. Eng. 1987.1:83-98.
3- Eskorchi A. M. 2006. Soil Mechanic Laboratory. Third publish. Tehran University Publication. Tehran.
4- Karbar H., and Soroosh A. 2012. Numerical Comparing Behavers Core dam with Vertical Core and Middle Slop Core. Journal of Civil engineering. (in Persian with English abstract)
5- Khor C., and Woo H. K. 1989. Investigation of Crushed Rock Filters for Dam Embankment. J. Geotech. Engrg. 1989. 115: 399-412.
6- Kharaghani S. 2005. Earth dam engineering. Shahid Chamran University Publication. Ahvaz.
7- Mishra G. C., and Singh A. K. 2005. Seepage through a Levee. International journal of geomechanics, ASCE 5:74-79.
8- Najafpoor Khoyegani N. 2013. Investigation Seepage Pattern in Earth Dam on Impermeable Base with and without Toe Drain by using physical Models. Agriculture Department. Shahrekord University.
9- Rahimi H. 2006. Earth Dam. Second Publish. Tehran University Publication. Tehran.
10- Shafahi Bajestani M. 2005. Hydraulic and Physical models. Second Publish. Shahid Chamran University Publication. Ahvaz.
11- Tahoni Sh. 2006. Implementation Principles in Earth Dam. 13th Publish. Thehran Pars Aien Institution. Tehran.
12- Terzaghi K. 1992. Der Grundbriich an Staveverken und Seine Verbutung. Die Wasser-Kraft, Vol. 17, 1922, pp. 445-449.
13- Terzaghi K. 1925. Erdbaumechanik auf Borden physikalischev, Grundlage, Devticke, Vienna, Australia, 1925.
14- Timothy D., Jafari N. H., Zhindon S. L., and Baghdagy A. 2016. Unsaturated and Transient Seepage Analysis of San Luis Dam J. Geotech. Geoenviron. Eng., 04016093.
15- Vafaeian M. 2006. Impalement Information for Earth Dam. Second Publish. Ardakan Knowledge Publication. Isfahan.
16- Yea G.G., Kim H. T., and Kim J. H. R. 2013. Rehabilitation of the Core Zone of an Earth-Fill Dam. J. Perform. Constr. Facil. 27: 485-495.