مطالعه و بررسی عددی سدهای خاکی بعد ساخت و اولین آبگیری (مطالعه موردی: سد خاکی دویرج)

کنترل ایمنی و پایداری سدهای خاکی در دوران ساخت، انتهای ساخت، اولین آبگیری و بهره‌برداری آن بسیار حائز اهمیت است. ارزیابی مقایسه‌ای نتایج تجزیه‌وتحلیل‌ها برای ایمنی ساختار و همچنین عملیات نگهداری منظم ضروری است. علاوه براین واضح است که مطالعات دقیق مبتنی بر چنین مقایسه‌هایی برای به دست آوردن تجربه برای طرح‌های آینده مفید خواهد بود. در این مطالعه سد خاکی دویرج از نظر پارامترهای فیزیکی مانند، جابه‌جایی‌ها، تغییر شکل‌ها، تنش‌ها، فشار آب منفذی و پایداری آن در پایان ساخت و اولین آبگیری موردبررسی مقایسه‌ای قرار گرفت. مدل‌سازی عددی با استفاده از دو نرم‌افزار flac 2d و geo studio با مدل رفتاری موهر کلمب (mohr–coulomb) انجام شد. نتایج بررسی‌ها نشان داد بیشترین نشست عمودی در تاج هسته رسی بعد از اولین آبگیری با مقدار 70 سانتی‌متر و همچنین بیشترین مقدار جابه جایی افقی در پایین‌دست سد برابر 12 سانتی‌متر رخ‌ داده است. در بررسی تنش‌ها نیز مشخص شد که مقدار بیشینه‌ تنش‌های حاصل در مقطع هسته حدود 1000 کیلو پاسکال به‌دست‌آمده است.

Numerical Study of Earthdams after Construction and First Impounding (Case Study of Doyraj EarthDam)

Engineering and economic investigations in dam construction projects throughout the world indicate that, in many cases, rockfill dams with impervious clay cores are the best selection for the final design (Rezaei and Salehi, 2011). This approach makes the investigation of different issues affecting the stability of rockfill dams worthwhile. In general, dam safety is the first and foremost reason for controlling deformation and physical parameters in dams. Another reason is the importance of basic design concepts for engineers to apply in future designs as well as understanding the resistive and behavioral characteristics of soil and pebbles. One of the most effective approaches for interpreting the mechanical and hydraulic behavior of structures such as dams is to use data and compare the results with numerical modeling predictions. In the field of earth and rockfill dams, monitoring of typical physicomechanical behaviors is a fundamental issue. Measurements of displacements, total stresses, pore water pressures, and arching ratio can be used to carry out a number of tasks (ICOLD, 1982), such as characterizing the dam’s overall behavior (Pagano et al., 1998), checking the behavior of specific zones, obtaining information about the in situ mechanical properties of embankment soils (Marsal and Resendiz, 1975), and finally, supporting the difficult task of evaluating dam safety and efficiency (Gould and Lacy, 1993). Justo (1991) and Naylor (1997) proposed methods for the incorporation of collapse settlement of rockfill into constitutive models. Naylor (1991) performed the finite element analysis for Beliche dam, a central core earth and rockfill dam, by considering the collapse settlement of the upstream rockfill in the modeling. The effect of pore water pressure dissipation in earthfill during construction was also considered by a number of authors including Eisenstein and Law (1977) and Cavounidis and Hoeg (1977), amongst others. For these cases, the incremental embankment construction was modeled as a twostage process, the first stage modeling the new layer construction using undrained properties for the core and the second stage modeling pore water pressure dissipation. Zomorodian and Kuchi studied internal deformation, pore water pressure, and total vertical stresses in Masjed Soleiman Dam and compared it to numerical results, they also showed that the development of excess pore water pressure in the clay core of zoned earth dams during construction may lead to the onset or progression of hydraulic failure.